International Journal of Biological Macromolecules Volume 72 Issue 2015 [Doi...

Please cite

ARTICLE IN PRESSG ModelBIOMAC 4576 112International Journal of Biological Macromolecules xxx (2014) xxxxxx

Contents lists available at ScienceDirect

International Journal of Biological Macromolecules

j ourna l h o mepa ge: www.elsev ier .com/ locate / i jb iomac

Review

Chitosan as a suitable nanocarrier material for anti-Alzheimer drugdeliver

JayrajsinQ1Institute of Res

a r t i c l

Article history:Received 1 JulReceived in reAccepted 28 AAvailable onlin

Keywords:ChitosanAlzheimers diBrain targetingAnti-Alzheime

agencies and manufacturers. 2014 Elsevier B.V. All rights reserved.

Contents

1. Introd2. Chitos

2.1. 2.2. 2.3.

2.4. 2.5.

3. Fabric3.1. 3.2. 3.3. 3.4.

4. Surfac5. Brain

5.1. 6. Regul7. Concl

Refer

CorresponTel.: +91 9638

E-mail add

http://dx.doi.o0141-8130/

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41 this article in press as: J. Sarvaiya, Y.K. Agrawal, Int. J. Biol. Macromol. (2014), http://dx.doi.org/10.1016/j.ijbiomac.2014.08.052

uction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 00an as a carrier material in anti-Alzheimer therapy. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 00Properties of chitosan . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 00Biodegradability of chitosan . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 00Chitosan modications for brain targeting and blood compatibility . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 002.3.1. Chitosan modication for brain targeting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 002.3.2. Chitosan modication for blood compatibility . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 00synergistic roles of chitosan in anti-Alzheimer therapy. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 00SiRNA targeting to brain by chitosan nanocarrier . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 00ation options for brain targeted chitosan nanoparticles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 00Ionic gelation/crosslinking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 00Micellization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 00Spinning disk processing technology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 00Emulsication method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 00e modications with ligands. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 00targeting with chitosan nanoparticles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 00Feasibility of non-invasive routes of administration by chitosan nanoparticle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 00

atory aspects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 00usion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 00ences . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 00

ding author at: Institute of Research and Development, Gujarat Forensic Sciences University, DFS Campus, Sector 18A, Gandhinagar, Gujarat 382018, India.344834/45.resses: jis [email protected], [email protected] (J. Sarvaiya).

rg/10.1016/j.ijbiomac.2014.08.0522014 Elsevier B.V. All rights reserved.y

h Sarvaiya , Y.K. Agrawalearch and Development, Gujarat Forensic Sciences University, Gandhinagar, India

e i n f o

y 2014vised form 24 August 2014ugust 2014e xxx

sease

r drugs

a b s t r a c t

Chitosan, a biocompatible natural polysaccharide is frequently reported carrier material in targeted drugdelivery to treat neurodegenerative disorders. Chitosan and its biodegradable products exert its bioactiv-ities on nerve cells and blood brain barrier at the molecular level, which are benecial in anti-Alzheimertherapy. Flexibility of surface modication, the ability to get attached with varieties of ligand moleculesand the formation of the stable nano complex in physiological condition make chitosan an adorable mate-rial for delivery of anti-Alzheimer drugs and siRNA to the brain. The success rate of nose to brain deliveryof anti-Alzheimer drugs enhances when chitosan used as a carrier material. This review covers direct andindirect anti-Alzheimer effects of chitosan, surface modication strategies to augment permeation fromthe bloodbrain barrier structure, different ligands reported for brain targeting of chitosan nanoparticlescontaining anti Alzheimer drugs, blood compatibility and widely utilized chitosan nanoparticle fabrica-tion techniques. Key intellectual claims are also condensed through patents to appraise chitosan as anattractive polymer for brain targeted nanoformulation which is currently facing oversight by regulatory

Please cite l. (20

ARTICLE IN PRESSG ModelBIOMAC 4576 1122 J. Sarvaiya, Y.K. Agrawal / International Journal of Biological Macromolecules xxx (2014) xxxxxx

1. Introduction

Applications of polymeric nanocarrier have astonished in recentyears because of its prominent role in therapeutic interventions inbrain disordrequires cethough druneurodegenapeutic invanticipatedsuffering ofmark in thfailures of sa greater secarriers andapeutic failis blood braby astrocytethe brain is compared tmakes BBB a drug subs[5,6]. BBB ethan 12 nmmore than 3impede prothese obstapolymeric investigatedchitosan owit a slight ed

Chitosanied in braisystems. Mious investalso widelytion of loadlung diseasdation prodmechanismN-terminalinammatoMoreover, bmodicatioadvantagesforming maacids to braof the appliery systembiomarkerswith bioact

2. Chitosan

2.1. Propert

Chitosana natural pcrustaceouslinear chainglucosaminbonds. Chitdeacetylatiotion and pochitin is cal

66% to 95% in marketed chitosan. Solubility of chitosan in acidicwater and interaction with negative charged substances are dueto protonation of amino group in water. Such distinctive nature ofchitosan among all polysaccharides enables it to form water sol-

lts lce thion.sicalre stylatiue t

lution dr

nanon caYang

sizedolecuight plish, hothlorvativvitieity. Dp fouts bio

odeg

tosane N ozymeta-Nnaseajor

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is e AD

conyloidan bietylwhena degther olecu

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chitohemihydeh ann. Achitoting omparticlteristive ctaken) du

that

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106 this article in press as: J. Sarvaiya, Y.K. Agrawal, Int. J. Biol. Macromo

ers. A successful therapy in neurodegenerative diseasentral nervous system (CNS) rejuvenation or protectiong delivery. Alzheimers disease (AD) is the most fatalerative disorder with the modest progress in ther-entions. Especially, 0.7 million aged Americans are

to die because of AD in year 2014, whereas people this deadly disease is going to reach at 13.8 millione USA alone by the year 2050 [1]. The recent clinicaleveral promising drug candidates in AD are spurringnse of urgency to investigate new targets, new drug

their interconnectivity. The prime reason behind ther-ure provocation of most of the agents in AD treatmentin barrier (BBB) wherein thin blood vessels are covered

foot processes in brain [24]. Vascular endothelium informed by comparatively tighter intercellular junctionso other parts of the body. This structural uniquenessan impermeable hurdle for foreign particulate includingtance and hinders its passage to amyloid rich brain partssentially inhibits the normal passage of objects more

in diameter and cellular endocytosis of objects with0 nm. Moreover, the extracellular space viscosity maypagation of the object in a human brain. To overcomecles, nanocarrier drug delivery systems like liposomes,nanoparticles and solid lipid nanoparticles are being

vastly with prolic end results [710]. Among them,ns certain characteristics and bioactivities that providege over other nanocarrier materials.

is a cationic polysaccharide which is extensively stud-n scaffold preparations and spinal cord implantableoreover, it has displayed multiple bioactivities in var-igations carried out in the last decade [1114]. It is

employed in nanoparticle preparation for transporta-ed drugs to targeted organs in case of cancer, diabetes,es and CNS disorders [15]. Chitosan and its degra-ucts, at the molecular level, exhibits anti-Alzheimers majorly by prevention of phosphorylation of c-Jun

kinase caused by -amyloid [16], inhibition of pro-ry cytokines and blockage of nitric oxide sythase [17].iodegradability, biocompatibility, exibility in surfacen and ease of multiple preparation methods are added

of chitosan, which makes it an attractive nanoshellsterial to achieve successful delivery of drugs and nucleicin interstices. The review is aimed to scrutinize reportscation of chitosan and its derivatives in nano drug deliv-

targeting Alzheimers disease. Furthermore, different and pathological conditions of AD are also correlatedivities of chitosan in the present work.

as a carrier material in anti-Alzheimer therapy

ies of chitosan

is a cationic heteropolymer obtained from chitin,olysaccharide present in the exoskeleton of shrimp,, fungi and yeasts [18]. Structurally, Chitosan is a

of randomly present N-acetyl-d-glucosamine and d-e units which are attached by beta (1,4)-glycosidicosan consists of an amino group at the C2 carbon aftern of chitin structure. When the degree of deacetyla-rtion of nitrogen is more than 60% and 7% respectively,led chitosan. DD (degree of deacetylation) ranges from

uble saenhancondit

Phytosan adeacetusage dous sochitosation ofchitosaing to of lowlow mlar weaccomNaNO2hydrocits deribioactidispartake umine i

2.2. Bi

Chiinto thby lyslase, bchitosatwo mtissuesthe brauid) diseasetext oftrial in-amChitosof deaclesser DD as cles. Olow mweightration rate dlinkedthan ctaraldeon higchitosaity of presentract cnanopcharacof posito be systemcluded14), http://dx.doi.org/10.1016/j.ijbiomac.2014.08.052

ike HCl salt and carboxylate salt. These groups furthere ability of chitosan to get soluble even in slightly acidic

properties and associated chemical behaviors of chi-rongly governed by its molecular weight and degree ofon [19,20]. High molecular weight chitosan connes itso high viscosity and very low solubility in neutral aque-n whereas similar properties of low molecular weightastically changes to widen its applications in prepara-particles for drug targeting. Encapsulation efciency ofrrier increases as molecular weight decreases accord-

et al. [21]. They reported high entrapment efciency (less than 70 nm mean diameter) NPs prepared fromlar weight chitosan (55 kDa) in their work. Molecu-reduction of high molecular weight chitosan can beed by chemical depolymerization through the use of

dilute sulfuric acid [22] and strong acids specicallyic acid, phosphoric acid and sulfuric acid. Chitosan andes exhibit variant properties, degradation behavior ands because of the existence of conformational structuralepending on the type of solvent, chitosan moleculesr different types of helical conformations which deter-activities in neuroprotection [23].

radability of chitosan

is transformed to oligomer before further conversion glucosamine unit in vivo. This degradation is catalyzedes [24], lipases, proteases, chitinase, chitin deacety--acetylhexosaminidase [25,26], collagenase [27] and

enzymes [28]. Lysozyme and chitisonase enzymes aresources of chitosan biofate which are present in manyuman body including brain. Chitinase is also present inith the noteworthy elevated level in CSF (cerebro-spinalg AD [29]. The level of chitinase during Alzheimersquivalent to its biomarker status consideration in con-diagnosis with 85.5% accuracy, observed in a clinicaltrast to 78.4% and 77.6% accuracy observed in case of

and tau respectively during the clinical study [30].odegradation was observed to be faster when degreeation (DD) is less than 70% and chitosan cytotoxicity is

molecular weight is low [31,32]. This emphasized onradation rate governing factor for chitosan nanoparti-similar reports afrmed higher rate of degradation oflar weight (Mw) chitosan compared to high moleculartosan [3335]. Crosslinking agent utilized in prepa-hitosan nanoparticles also inuences its degradationding on crosslinking mechanism. Ionic gelation crosssan by use of TPP (Tri poly phosphate) degrades slowercally cross linked chitosan nanoparticles by use of glu-

[36]. The effect of cross linkers is more pronouncedd medium Mw chitosan in comparison of low Mwvailability of amine group also inuences susceptibil-san for enzymatic degradation by microbial enzymesless digestion of N-stearoylchitosan in gastrointestinalared to raw chitosan [37]. Biodistribution of chitosane after I.V. (Intravenous) injection depends on surfacetics and size. Chitosan NPs with complete neutralizationharge and more than 200 nm diameters were observed

up by the spleen and liver RES (Reticuloendothelialring an investigation by Zhang et al. [38]. They con-

hydrophobic modication of chitosan by incorporating

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ARTICLE IN PRESSG ModelBIOMAC 4576 112J. Sarvaiya, Y.K. Agrawal / International Journal of Biological Macromolecules xxx (2014) xxxxxx 3

N-octyl-O-sulphate moiety showed maximum accumulation inkidney, liver and spleen followed by minimum brain uptake. Inone of the empirical outcome, Costa-Pinto et al. [39] reportedvascularization promotional activity of biodegraded product of chi-tosan whenshowed eviof chitosan.

2.3. Chitosacompatibilit

Blood coface adhesinanocarrier

2.3.1. ChitoFeasibili

delivery of versatile chefcient to(poly (lacticto enhance [40,41]. Therelease of aplex formatand cellularby hydrophsurface mayblood cells of chitosanvention of aof segregatethe blood b

Among aTMC(N-Triming with anpositive chprotein preinteractionstion of PLGAcoupled to carbodiimidnanospherethe brain-tenzyme Q1neurodegenthe ionic gethiocyanatestudy of br[42], especias the tranwith polyeenhanced bits efciencdelivery to polyplex un

In addittosan and tof nanocarroprotectivwith unmobe equal tochitosan nabate surfacto stabilizetant molec

nanoparticles, which can eventually help the nanoparticle to reachat BBB in proportionally higher amount. Kulkarni et al. [49] notedthat nanoparticles with less than 100 nm size can cross BBB moreeffectively than higher sized particles when chitosan surface is

ed byodiation

ChitoD, bod cnsityompveal diesovideaterin nathe cilitager dedicivelyano

, moa hign deic ciincom, plaion, ion articlow b

totaomp2] th

by rand tmerecrerotoitosassionn coategiade catiotibiliancen naf cytood againphilially an deity, an, N-in tar

nerg

is c forminute

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lysozyme mediated degradation was prominent. Thisdence of bioactivity exerted by biodegradation product

n modications for brain targeting and bloody

mpatibility, blood stability and BBB epithelial sur-on are prerequisites for successful brain targeting by

material to treat neurodegenerative disorders.

san modication for brain targetingty of surface modication of chitosan structure allowsbrain targeted nanoparticles with desired features andaracteristics. Moreover, modied chitosan is equally

cap surface of other nanocarrier materials like PLGA-co-glycolic acid)) and PLA (poly lactic acid) with a viewBBB permeation, cell compatibility and serum stability

hydrophobic portion of chitosan derivative assists innionic ions which are attached with chitosan by poly-ion. At the same time, genetic transfection modulation

adsorption on surface of neuronal cells are facilitatedobic moieties of chitosan derivatives. Cationic chitosan

get attached to albumin and results in aggregation ofafter I.V. administration, but hydrophilic modication

enhances blood stability of chitosan polyplex by pre-lbumin and chitosan complication. Here, the existenced nanoparticles allows enhanced permeation throughrain barrier and neuronal cells.ll the reported modied chitosan derivatives (Fig. 1),ethyl chitosan) is a vastly studied form for brain target-

ti-Alzheimer and other neuroprotective drugs becausearged TMC and anionic sialic acid residues of glyco-sent on blood brain barrier undergoes electrostatic. TMC is reported for its usefulness in surface modica-

nanoparticles for brain targeting. TMC was covalentlythe surface of PLGA nanoparticles (PLGANP) via ae-mediated linkage to act as surface modier for PLGAs. The senile plaque and biochemical tests conrmedargeted effects of TMC/PLGANP for delivery of Co-0 and 6-coumarin [41] in the treatment of AD associatedration. Furthermore, TMC nanoparticles prepared bylatin method can easily entrap FITC (uorescein iso-) which can be used for labeling purposes while theain targeted drug delivery in neurological disordersally to demonstrate absorptive mediated transcytosissport mechanism. TMC also makes polyionic complexthylene glycol (PEG) and such nanoparticles possesslood stability. These nanoparticles have also exhibitedy to act as a carrier of SiRNA (small interfering RNA)neuronal cells because of enhanced stability of TMCder charge neutralizing biological environment [43,44].ion, Zwitter ionic chitosan derivatives, PEGylated chi-ween 80 coated chitosan [45] are also popular formsrier materials to persuade BBB permeation of neu-e agents. In a contrary result, chitosan nanoparticledied surface delivered the drug across BBB found to

the amount of drug delivered by Tween 80 coatednoparticles [4648]. Though, the non ionic polysor-tant in low concentration (0.5% w/V) can be used

the chitosan nanoparticle formulation. This surfac-ule contributes in the prevention of aggregation of

moditural mperme

2.3.2. In A

red blolow deticle ccan relity stuhas prrier mchitosaery to also fafor lonnanomextensketed nextentact as chitosasystemhemo ulationactivatalteratnanopin narrwith ahemocet al. [5causedbrane re-polywith dmore pized chsupprechitosathe strwas mmodicompaimportchitosament oand bllished amphichemicChitospatibilchitosaits bra

2.4. sy

AD plaqueis a m14), http://dx.doi.org/10.1016/j.ijbiomac.2014.08.052

polyethylene glycol. Hence, numbers of chitosan struc-cation approaches are available which can enhance BBB

effectively.

san modication for blood compatibilitylood composition is altered, which includes damagedell membrane structure and elevated level of oxidized

lipoprotein [50]. It is not yet studied whether nanopar-osition exposed to blood of an AD affected personinformal hemo-behavior or not, but hemocompatibi-

of modied chitosan nanoparticles in healthy serumd decent results and made it an acceptable nanocar-al. Chemical modication of surface characteristics ofnocarrier is almost a prerequisite for targeted deliv-amyloid rich structure of the brain. This modicationtes availability of nanoparticles in systemic circulationuration bypassing opsonization. As per USFDA and EU,ine for blood infusion or injection required to study

for its hemocompatibility. Though majority of the mar-formulation causes an infusion reaction up to a certaindied chitosan nanoparticles hold the expectation tohly blood compatible nanocarrier. Brain targeting ofrived nanoparticles when administered or reached inrculation before reaching at AD affected brain parts, itspatibility can be evaluated through thrombosis, coag-

telet activation, blood cell changes and complementarymacrophage uptake of nanoparticles and rheologicalof blood [51]. Even after reaching to cerebral area,es gets exposed to blood plasma and blood componentrain capillary network formed by 100 billion capillariesl of 650 km capillary lengths. The necessity of chitosanatibility improvement was rst introduced by Maletterough his reports of red blood cell rouleaux formationeaction between the negatively charged red cell mem-he cationic chitosan solution mediated crosslinkage orization. This phenomenon is observed to be increasedase in molecular weight of chitosan due to more andnated amine group becomes available in depolymer-n [53]. In a similar work, Bentholon et al. [54] reported

of complement activation by high molecular weightmpared to short chain chitosan. Empirical review ofes for improvement of hemocompatibility of chitosanby Balan et al. [55], who emphasized on chemicaln of polymer and the association of chitosan with hemo-ty enhancing capping agents. Xu et al. [56] described the

of the brain targeted succinic anhydride-conjugatednoparticle that can fulll dual objectives of impedi-okine production and RBC aggregation. Biocompatibilitycompatibility of N-octyl-O-glycol chitosan was estab-st FDA approved product-Taxol and it has proved thatc modication is the ultimate advancement in derivingmodied chitosan with blood compatible nature [57].rivatives with signicant improvement in blood com-re represented in Fig. 2. Among which, alkylglyceryltrimethyl chitosan and PEGyalted chitosan have provedgeting efciency by crossing BBB.

istic roles of chitosan in anti-Alzheimer therapy

haracterized by an extracellular deposition of senileed by amyloid-beta peptide (A) in the brain. This

level steady state (2227 ng/day and 710 mg/year),

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Please cite


Fig. 1. Variou bbrev

deposition Oligomer acausing bration, hyperpto form neutually [60].damage nethe death oular level msynaptic sigTau tangle fdamage, altcleaving enproducts), ncomplicatioMoreover, uptake by ahyper-excitare also pabecomes mregeneratiocells of othNogo-A and

Chitosanvarious patrect mechasurface, whstatically. Fappealing dsues selectineuron, chiand physiolcompromis

Few stu[66] of chi

n by and

ande reqtrati400

(reakapp

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327s options of chitosan modication for preparation of brain targeted nanoparticles. A

with the invisible symptomatic response initially [58].ggregation on neuronal end and on receptor surface isin inammation, synaptic dystrophy [58,59]. In addi-hosphorylated tau protein associations are consideredrobrillary tangles inside the nerve cell bodies even-

In continuation of this, the microtubules split up anduronal messenger system which later transforms inf the nerve cells leading to dementia. Though molec-

chitosamationthe DDcharidconcenbe 10of ROSfactor- this article in press as: J. Sarvaiya, Y.K. Agrawal, Int. J. Biol. Macromol. (20

echanism contributing to neuronal damage and loss ofnaling is more or less inuenced by amyloid plaque andormation in the brain, many other factors like vascularered level of Neprilysin, Insulin, BACE 1 (beta-site APPzyme 1), RAGE (Receptor for Advanced Glycation End-eurosteroids, TNF (Tumor necrosis factor), metabolicns also contribute in the fate of the AD affected brain.lysosomal failure, inammation, hypoxia, less glucoseffected part, alteration in signaling proteins, circuitryability and alterations in glutamate receptors [61,62]thological conditions to be countered. The diseaseore fatal because of low efciency of neural cells forn and restoration of neural elasticity in comparison ofer organs due to regeneration constraining ability of

NgR1 receptor proteins [63,64]. and its biodegradation products resists progression ofhological conditions of brain in AD by direct or indi-nism of actions apart from its ability to act as a cationicich get attached with anionic epithelium of BBB electro-urthermore, brain targeting of drug by using chitosan isue to its ability to recognize and adhere to neural tis-vely [65]. By such preferentially targeting of damagedtosan facilitates restoration of normal neural activitiesogy which otherwise altered under inuence of AD anded BBB (Fig. 3).dies alluded dose dependent neuroprotective effectstosan oligosaccharides, a biodegradation product of

vated protewhen the oOther anti-BACE inhibof RAGE inexpressed primarily rto brain thpotent neulate cyclasefactor can bBoth the poreceptor forcell line-de

The brainot only librovascularpart betweeparacellulaof tight junmajor compof chitosan by Brian et meation byprotein. ThoBBB [77], sage brain taiations: HA: Hyaluronic acid; LS: Lecithine; G: Carragenam polymer.

demonstrating its ability to restrict microglia inam- oxidative damage to nerve cells [6771]. In this context,

the degree of polymerization of chitosan oligosac-uired to be >95% and 26 respectively, whereas theon of the polymer as a therapeutic agent is required tog/ml in the AD affected area. Restriction in the activities

ctive oxygen species), NO (nitric oxide), NF-kB (nucleara B), AP-1 (activator protein-1), MAPK (mitogen acti-

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33514), http://dx.doi.org/10.1016/j.ijbiomac.2014.08.052

in kinase) are among the direct measures contrivedptimum concentration of chitosan is present in biouid.inammatory response of chitosan is mediated throughition activity which restricts pro inammatory actions

Alzheimers disease [66,72]. RAGE receptors are overin epithelial cells of AD affected blood vessels andesponsible for the inux of plasma amyloid peptiderough the BBB. Rat et al. [73] showed multi targetroprotective polypeptide like PACAP (pituitary adeny--activating polypeptide) and glial derived neurotropice delivered to the brain by complexing with chitosan.lypeptides are acting as ligands for RAGE (transporter

advanced glycation end products) and receptor of glialrived neurotrophic factor respectively [74].n targeting mechanisms of chitosan nanoparticles aremited to its molecular level interaction on the cere-

endothelial cell surface, but extended to close junctionn endothelial cells also. Chitosan is reported to enhancer permeability of molecules by tempting redistributionction protein ZO-1 (Zonula Occudens) [75] which is aonent protein in tight junction in BBB. This bioactivityresembles molecular mechanism of nicotine as reportedal. [76], they have depicted increase in in vivo BBB per-

nicotine is mediated by redistribution of tight junctionugh the expression of ZO-1 is suppressed in AD affectedtill interaction of chitosan with this protein encour-rgeting without surface modication of nanoparticles.

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Alzheimerslated with fdeterminestion of neubrain and cinammatiotion of amyand neurovcountered tosan is repo[78]. In conof angiogenwere carriecancer.

One of tby the dysbarrier. Leaof iron, copof the diseabeen evaluaing outcommaterial forsequently, facilitate nopart, but albrain parenligand on chendocytosis

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Fig. 2. Types of chitosan derivatives with proved hemocompatibility

disease progression enhances BBB disruption corre-aulty clearance from brain and across the BBB primarily

amyloid- retention in the brain, causing the forma-rotoxic amyloid oligomer strand the promotion oferebrovascular amyloidosis. Enhanced level of ROS andn in AD affected brain is promoted by the accumula-

loid-beta in cerebral arteries leads to micro hemorrhageascular alterations in AD. This vascular damage can beby use of chitosan as a carrier material because chi-rted to promote wound healing and neovascularizationtrast, few investigations have also proved inhibitionesis activity of chitooligosaccharide, but such studiesd out to see the effect of chitosan in angiogenesis of

he major pathological mechanisms in AD is exhibitedfunctional homeostasis of metals by the blood brainky blood vessels contribute in abnormal accumulationper and zinc in AD affected brain with progressionse [79,80]. Chitosan conjugated chelating agents haveted in other than anti-Alzheimer purpose with promis-es [81,82]. These studies endorse chitosan as a carrier

metal chelating therapy in Alzheimers disease. Con-the nanoparticle-chelator system possess ability tot only metal binding of chelating agent in affected brainso elimination of metal complexed chelator from thechyma. This is possible if apolipoprotein E is used asitosan nanoparticle with a view of receptor mediated.

Along wbioactive, brier in brainencouragedits ability totides, bioloof ligands.

2.5. SiRNA

SiRNA (length and agent whenroot causesdrial metabin many neease in agethe therapeof neurodeease linkedprecursor psions are pmethylation

SiRNA thable nanocablood vesseneuronal crequisites o14), http://dx.doi.org/10.1016/j.ijbiomac.2014.08.052

in contrast to unmodied chitosan.

ith the aforementioned dual application of chitosan as aiodegradable supramolecule and material for nanocar-

deliver, use of chitosan in Alzheimers disease is also by reports of successful drug targeting to brain due to

deliver siRNA (small interfering RNA), proteins, pep-gically derived drugs and compatibility with numbers

targeting to brain by chitosan nanocarrier

small interfering RNA) strand with 2025 base pairwith negative charge is mainly used as a therapeutic

over activity of enzymes and certain proteins are the of the disease. Epigenetic modications and michon-olism alterations are encompassed among key reasonsurodegenerative diseases, including of Alzheimers dis-d person. Several lines of evidence have shown thatutic activity of siRNA has a potential for the treatmentgenerative diseases by selectively suppression of dis-

genes [83,84]. More specically, BACE 1, APP (Amyloidrotein), PS1 (presenilin 1) and PS2 genes over expres-redominant in AD due to genetic mutation caused by

of DNA and alteration of miRNA [85].erapy in Alzheimers disease essentially requires suit-rrier which can protect siRNA during its passage fromls and successfully deliver a genetic load in targetedells [86]. Positively charged chitosan fullls the pre-f siRNA containing nanoparticles by its ability to cross

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Fig. 3. Molecular Targets of chitosan and its biodegradation units in pathological conditions of AD: (1) Leptin serum level enhanced by chitosan and cascade events inhibitsCNS inammation. (2) Insulin level enhanced by chitosan. (3) Tight junction protein redistribution achieved by chitosan facilitates access of drug loaded nanocarrier tonerve tissues. (4) Chitosan makes complex with metal ions and protects neurons from source of free radicals for nerve damage and amyloid beta plaque formation. (5) BACEinhibition by chitosan prevent peptide production. (6) EPCP (Endothelial protein C receptor) down regulation by chitosan prevent inammatory response of nerves andnerve apoptosis. (7) Anticoagulant effect of chitosan prevent blood clots in amyloid saturated blood in brain hemisphere.

Fig. 4. Covalent binding between chitosan and siRNA: in chitosan nanocomplex formation for brain transfection. N/P ratio in nanocomplex determines siRNA stability andrelease during drug targeting.

Please cite l. (20


the blood brain barrier and effective gene transfection in neuronalcells. Positively charged chitosan forms nanosized polyplex by ionicinteraction with a negatively charged siRNA strand under acidiccondition as depicted in Fig. 4. Under alkaline and neutral physio-logical condbonding antrophoresisagainst serusiRNA remavivo study.48 h of the of free siRNcorona arouportation almaterial an

Alzheimdation of chcontent to ity of genetime by othSiRNApolymaterial stacellular sitemolecular siRNA to v90% gene siBBB by chitoexpression the immortof these inwith a viewgp-glycoprothe superiotors are ove(Tumor nective diseasethe same titor II) [92], disease. Kimdamage by use of anti-brain targettect siRNA in brain in can be impfection of sof trimethyenhance bioing in anti ipeptides attin this case neuronal ceexceptional

Success rodegeneraparameterssuch factorovercomes ment of siRand inadeqsiRNA durin2014 two aand Drug Ad(Kynamro).positive pro(a monome

regulatory approval of RNA-based therapy for CNS is still a vision forthe future, but chitosan has been proposed as a reliable alternativefor comparatively high toxic carriers like PEI (polyethyleneimine)and viral vectors used in several IND products.

ricatartic

tosanto mrativicated nanic gchnoquesrote

Necell in

nic g

tosansslins min essug emuczym6

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studes m8,99]

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of noneCycloNPs pin FITr toal mitosanonddiethnatees, eannicalso. rt ne

lead chidizel andchitodiumone an.

icelli

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itions, spontaneous polyplex is retained by hydrogend hydrophobic interactions as evident by gel elec-

[87]. ChitosansiRNA nanocomplex makes hindrancem nucleases degradation of siRNA. Studies suggest thatins fully protected up to 7 h in 50% serum during ex

Complete degradation of siRNA was noted only afterincubation time with serum in contrast to 30 min lifeA in 5% serum containing medium [88]. Formation ofnd chitosan nanoparticles during blood capillary trans-so makes barrier a between entrapped gene interferingd its degrading enzymes present in the blood.ers disease requires chronic treatment and slow degra-itosan is an added advantage in delivering the genetictarget cells for longer duration because the major-

silencing effects are observed for a short span ofer rapid degrading nanocarrier materials. Moreover,ethylenimine complex suffers from issues of geneticbility in nanocomplex and readily dissociation at the

of action [89]. When fully deacetylated chitosan withweight from 34 kDa to 140 kDa was used to deliverarious cell lines during in vitro experiments, aboutlencing efciency was resulted. SiRNA transfection tosan nanocarrier have shown hampered p-glycoproteinwhen siRNA entrapped nanoparticles were exposed toalized rat endothelial cell line RBE4 [90]. The results

vitro study opens up avenues for in vivo evaluation to enhanced drug permeation through BBB by alteringtein efux system, especially from the brainstem andr temporal cortex sites of the brain where P-gp recep-r expressed in Alzheimers disease [91]. Level of TNFR Irosis factor receptor I) is elevated in all neurodegenera-s with active participation in neuronal cell apoptosis. Atme expression of TNFR II (Tumor necrosis factor recep-which is a neutopreotective domain, decreased in AD

et al. [93] reported signicant reduction in neuronalsuppressing blood and brain TNF-alpha production byTNF-alpha-siRNA IV injection. RVG peptide utilized foring of systemic administered siRNA have shown to pro-in blood serum but no enhancement of bioavailabilitycomparison of unmodied siRNA. This circumstanceroved by the use of chitosan as nanocarrier for trans-ame genes. In vivo brain imaging revealed the abilityl chitosan nanoparticles tagged with RVG peptide toavailability of siRNA in brain [94,95]. TNF gene silenc-nammatory condition was also achieved by cysteineached on chitosan nanoparticles, though drug targetingwas arthritis [96,97]. Moreover, nucleic acid delivery toll is possible by TMC micellar nanospheres due to its

pH stability and slow degradation in vivo.of genetic transfection by chitosan nanocarrier in neu-tive diseases is dependent on different formulation

and properties of chitosan grade. Consideration ofs like N/P (nitrogen/phosphorous) ratio, pH and DDinherent concerns of siRNA delivery to brain like detach-NA from chitosan skeleton, insufcient cellular uptakeuate transportation to the cell nucleus, degradation ofg blood circulation and in extracellular space. As ofntisense drugs have been approved by the U.S. Foodministration, Fomivirsen (Vitravene) and Mipomersen

Recently Alnylam Pharmaceuticals announced theirgress in clinical trials of siRNA therapy by use of GalNacr of chitosan) conjugation with siRNA. The hopeful

3. Fabnanop

Chiibility Compato fabrtargetelarly. Iodisk tetechnineuropbelow.nanosh

3.1. Io

Chical crorequireers as ahigh drsesses and enFe(CN)ionic gphate)recentprovidTPP [9playedbarrierin casemoqui[103], [106]. tinent in ordeconfoc

Chiacid, chdrin, sulphocyanatacid, tphate to exestudiestargetelate, oxalcohoers in like Sotophenin hum

3.2. M

Shaaggregrotoxic14), http://dx.doi.org/10.1016/j.ijbiomac.2014.08.052

ion options for brain targeted chitosanles

as a nanocarrier material possesses excellent ex-ake drug entrapped nanoshell by various methods.ely requirements of lesser harsh conditions required

chitosan in nano form supersede its selection in brainnodelivery of proteins, enzymes and siRNA particu-elation and in situ crosslinking, micellization, spinninglogy and emulsication methods are the most in focus

of chitosan nanoparticles formation containing targetedctive substances in Alzheimers disease as scrutinizedessity of neuronal cell targeted ligands, stability of

normal and altered homeostatic condition.

elation/crosslinking

nanoparticles are prepared by ionic-gelation (physi-king) or covalent crosslinking (chemical crosslinking)ld processing condition and mere polyionic cross link-ential adjuvant. Though covalent cross-linking providesntrapment efciency, the later type of cross-linking pos-h more sustained drug release mechanism due to its pHe stability in vivo. Inorganic ions, such as Fe(CN)64,citrate and calcium ions are also used frequently foron of chitosan other than the use of TPP (Tri poly phos-

has been widely exploited for gelation purpose, buties suggest that pyrophosphate as an ionic crosslinkerore colloidal stability to chitosan nanoparticles than. Chitosan nanoparticles prepared by use of TPP dis-in targeting efciency by both in vivo blood brainmeation studies and ex vivo neuronal uptake studiesvarious anti-Alzheimers therapeutic agents like Thy-

[100], Rivastigmine [101], Venlafaxine [102], Tacrinephosphamide [104], Caspase inhibitors [105], Estradiolrepared by this method are also found to be more per-C (uoroscein isothiocyanate) labeling of nanoparticle

study internalization and cellular uptake imagine bycrography.

easily forms poly electrolyte complex with hyaluronicroitin sulfate [107109], genipin [110112], epichlorhy-yl squarate, Hexamethylene-1, 6-diaminocarboxy-, dialdehydes like glutaraldehydea and glyoxal, diiso-poxides, triuoroacetic acid, glycerol phosphate, oxalic

acid, pyrophosphate and Sodium hexa meta phos-Among these, glutaraldehyde and glyoxal are reportedurotoxicity and cytotoxicity respectively in differentding to a strangled preference for their use in brainitosan nanoparticle preparation. Moreover, PEG diacry-d beta cylcodeztrine, scleroglucan, telechelic-poly vinyl

PEG derived dialdehydes are also used as crosslink-san matrix, but they require polymerization initiators

cyanoborohydrine and 2,2-dimethoxy-s-phenyl ace-which are not utterly studied for their safety concerns

zation

al. [113] reported ability of micellar structure to inhibit of beta amyloid peptide and its conversion into neu-ters due to structural resemblance between micelles

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and biological membranes and surface charge of micelles. An FDAapproved anti-Alzheimer drug, Rivastigmine was also evaluatedby Lu et al. [114] for its usefulness against intracellular oxidativestress after loading in polymeric micelles. They substantiated proofof concept cells againssurface loadstrated succresearch reaction withThT (Thioainteraction in spite of [116,117]. Tin drug delibeta aggreg

Amphiptosan) derivon the typecan be lmto enhancemerit of rePropofol withe marketchitosan mthrough BBulated as oattention into improvelow molecuresistance dcritical asso(polycaprollem of staband dissolurange of co-of chitosan physiologicvalue [122]

3.3. Spinnin

Principleutilized in aration like considered nanoparticlsize and shcle generatagglomeratwith high zeeters to be cof mixing aformulationsolvent (acplays a crittration of Cenormous esize from in1000 rpm dwork, they chitosan nane particlepathway annanosphereutilization o

diseases. SDP method is also useful to develop bottom up princi-ple based solventnon solvent nanoprecipitation. This concept wasutilized to prepare curcumin nanoparticles with narrow size distri-bution and enhanced water solubility [127] which can be utilized

r for stratosan roced

agg8% drstemt in ng. Inlity ohniqplex

ulsi

emuarticl

precally

hydationditios souls

enizhereby em

15.2cinatr opi

of c33]. sslinn diete red of tyde) que o

face

in heh mand panneort a

expomisracelaren

ion, majorrierffectn naogniegenors or theas a some

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in drug loaded micelle carriers ability in protection oft AB-induced injury. Dynamically polymer micelles withed Tat peptide, after intra nasal administration demon-essful delivery of nucleic acid to brain tissues in variousports [115]. The natural afnity of beta amyloids inter-

micellar structure is implicit from amyloid staining byvin T) micelles. This staining is a result of hydrophobicand the role of positive charge on Thiavin T molecule,incessant speculations for exact mechanism behind ithese all emphasize on utilization of chitosan micellesvery of anti-Alzheimer agent and prevention of amyloidation.hilic chitosan (e.g.: stearoyl, palmitoyl and octanoyl chi-atives self-assemble into nanoszied micelles depending

of solvent used. Further, outer surface of the micelleed by cross linker to form the structure of nanoshell

integrity of the nanostructure. This method also bearsquiring mild processing parameters. The efcacy ofth micellar formulation was observed to be more thaned injectable product conrming BBB permeability oficelle [118]. Mechanism behind micelle permeabilityB is not yet clear, but inhibition of efux pumps is spec-ne of the causes [119]. Chitosan micelles have gained

CNS targeted dosage form design due to its ability solubility of hydrophobic drugs, more stability thanlar weight surfactant micelles, ability to overcome drugeveloped by target cells and comparatively a lowerciation concentration [120,121] required. PEG and PCLactone) block co-polymer derived micelles faces prob-ility in biological uid due to less resistance to dilutiontion because of higher critical micelle concentrationpolymers. In contrast, phase behavioral disparity in casegraft copolymer micelle is observed by high stability inal condition due to low critical micelle concentration.

g disk processing technology

of conventional ionotropic gelation is extensivelydvanced technologies of chitosan nanoparticle prepa-SDT (spinning disk processing technology). SDT isa preferred one for large scale production of chitosanes due to its distinctive merits, including remarkableape control of nanoparticles, small sized nanoparti-ion compared to conventional methods and control onion of particles by formation of stable nanoparticlesta potential (>45 mv) [123,124]. Manufacturing param-ontrolled are temperature, disk surface property, speednd the rate of introduction of reactants in SDT whereas

parameters like concentration of chitosan, acidity ofetic acid concentration), concentration of cross linkerical role in the overall quality of the product. Concen-hitosan solution from 0.25% w/v to 0.5% w/v impart anffect on particle size with more than tenfold increase initial 20 nm particles while SDT method was used withisk speed as stated by Loh et al. [125]. In a separatementioned efciency of SDT to prepare monodispersednoparticles of 2025 nm size and importance of ultra-s in high cell [126]. Moreover, augmented paracellulard facilitation of the cell nucleus targeting of chitosans observed by confocal microscopy in their work signifyf the SDP method in SiRNA therapy in neurodegerative

furthedemonof chitwise paroundwith 8high syconceptargetitunabithe tecof com

3.4. Em

Thenanopfor thespecitainingpreparthe adaqueouo/w emhomognanosppared size offor vacof otheulation[1311cal crochitosacomplthe enraldehtechni

4. Sur

Brathrouglular aion-chtranspdiseasecomprthe pabrain pconditis the nanocain AD achitosaing recneurodreceptated foto act of lyso14), http://dx.doi.org/10.1016/j.ijbiomac.2014.08.052

chitosan nanoparticle delivery. Huanbutta et al. [128]ed multi-step, spinning disk processing for preparationnanoparticles loaded with diclofenac sodium. The step-ure was able to coat pH responsive acrylate co-polymerregation of 10 nm chitosan nanoparticles. The end resultug entrapment efciency from the utilized method andic outreach of chitosan nanoparticles possess proof ofnon-invasive, oral delivery of nanomedicine for brain

spite of the feasibility of multistep processing and nef coated nanoparticle characteristics attained by SDT,ue is yet to be veried and modied in the preparation

composite nanoparticles with ligand tagging.

cation method

lsion solvent diffusion method of preparing chitosanes was derived from method utilized by Niwa et al. [129]paration of PLGA-based nanoparticles. This method is

utilized for preparation of chitosan nanoparticles con-rophobic drugs. The general methodology involved in

of chitosan nanoparticles by emulsication requiresn of an organic phase containing the drug to chitosanlution and a stabilizer under stirring [75]. Further,ion formed by rst step is exposed to high pressureation followed by removal of organic solvent. Chitosans containing F-Ab (sub fragments of amyloid beta), pre-ulsication method yielded end product with sphere

3 10.97 nm, was successfully utilized as a nano-carrierion in Alzheimers disease [130]. This result was in linenions giving attention to usefulness for chitosan in reg-ellular and humoral immunity and microphage activityIn general, investigators highlights inclusion of chemi-king of chitosan as an essential step after preparation ofspersion is emulsied with surfactants. Lacunae in themoval of harmful solvents (e.g.: acetone, chloroform) athe process and addition of toxic crosslinker (e.g.: glutu-is a matter of enormous concern in the selection of thisf nanoparticle preparation aimed with brain delivery.

modications with ligands

misphere access for chitosan nanoparticles is possibleny pathways at blood brain barrier, including transcel-aracellular diffusion, receptor mediated transcytosis,l activated transport, facilitated diffusion, active efuxnd carrier mediated transcytosis. Genes of Alzheimersress its multiple activities in microvascular damage anded blood brain barrier. This enhances the chances oflular pathway of chitosan nanoparticle transmission tochyma and nerve cells. Apart from this late diseasedreceptor mediated and carrier mediated transcytosisr pathway for BBB permeation [134]. Ligand tagged

design accomplishes outreach of therapeutic substanceed parts of the brain more prominently than untaggednocarrier. Currently multi-ligand approach is also gain-tion to make enhanced use of the complex nature oferative diseases in terms of up regulation of certainn brain epithelial cells. Ligands have been substanti-ir efcacy to get linked with chitosan nanoparicles andTrojan horse which can bypass the degradation effects of cytoplasm during movement from luminal side to

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Please cite


Table 1Lingands utilized for delivery of chitosan nanoparticles in anti-Alzheimer therapy.

Ligands Bridge for surface Reference

Magnevist (Magent)

Transferrin mantibodies

Transferrin

Insulin and Igrowth fac

Intramembrfragments(Vaccinati

Glutathione

Rabiesvirus 29-Cys pe

Other potenTat Peptide, Enkephalins

a Not yet enanoparticles.

the abluminnanoparticlacids, resemtransferringAD as in casrier transpoaffect recepwhich ultiming carrier tand neuronnanoparticl

5. Brain ta

5.1. Feasibichitosan nan

Nose toemerged asders. Intranstrongly bystudies. Recinsulin for Ain the level like growthof administaffected perbioavailabilto its absorpby the intrashown 14NGF (nervevitro and inused as a batrans-olfactof 0.25% w/vof olfactory

Use of chitosan and its derivatives like Chitosan-PLGA conju-gate, in nanoparticle preparation for nose to brain targeting inAlzheimers disease has been considered and demonstrated in var-

tudies, exploring three distinct pathways through whicharticld tratingeutic

moelivtratetraticomcannes locreasug weporedi

on to chito att

to admis alssal a

et anopary ax

to bn chanoedhes

toxi and nt co

stillr CNrnaryiveryhe d

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705functionalization

RI contrast Conjugation [104]

onoclonal Chitosan-PEG-Biotin-Steptavidinlinkage

[105]

Palmitoylated glycol chitosanby using dimethylsuberimidatemediated covalent linkage

[137]

Ion complexation with Fattyacid-modied OCMCh(O-carboxymethyl chitosan)

[138]

nsulin liketor

Nanocomplex formation [137]

anous of Aon)

Direct adsorption on chitosannanospheres

[130]

Covalent attachment tochitosan followed bynanoparticle formation

[139]

glycoproteinptide

MAL-PEG-NHS linker [140]

tial brain targeting ligands reported in brain targeting studiesa arenon-toxic analog of diphtheria toxin and tetanus toxin,, Thiamine, Leptin and Angiopep.

xtensively studied in anti-Alzheimer therapy involving chitosan

al side. Other than listed, neuronal cell specicity ofes is enhanced by RDP (a novel peptide with 39 aminobling RVG) [135,136] as a ligand. Transcytosis receptor,-not predominantly present on cell surfaces affected bye of cancer cell, but still reported to enhance nanocar-rt facilitation through the BBB. Chitosan is observed totor protein redistribution in the close junction of BBBately affects adsorptive endocytosis of drug contain-hrough clathrin and caveolin mediated pathway. Brainal cell specic ligands tagged successfully on chitosanes are summarized in Table 1.

ious snanoptory antermintheraping thebrain das illusconcenery in laser sparticlfold intide dr[153] rticles mattentiloadeddrug tcarriernasal adiol waintranaMistrythat naolfactoportedbetweelarly, nmucoacliliary

I.V.tic ageAD butriers fo(quatefor del3% of t this article in press as: J. Sarvaiya, Y.K. Agrawal, Int. J. Biol. Macromol. (20

rgeting with chitosan nanoparticles

lity of non-invasive routes of administration byoparticle

brain targeting of therapeutic macromolecules has a viable approach for treatment of neurological disor-asal drug delivery for treatment of AD is recommended

many investigators with evidences from preclinicalent success in clinical trials of intranasal therapy oflzheimers disease has demonstrated an acute increaseof insulin in the AD affected brain. Activation of insulin

factor receptor and anti-amyloidogenic mechanismering insulin can reverse cognitive impairment in ADsons [141143]. Yu et al. [144] rst reported enhancedity of insulin by use of chitosan solution (1.5% w/v) duetion enhancing capacity when solution is administerednasal route. Chitosan solution as aqueous vehicles has

fold increase in the bioavailability of the brain targeted growth factor) peptide via the nasal route during in

vivo experiments. Bovine olfactory epithelium wasrrier in these experiments. Further, Nearly 34% drop inory epithelial electrical resistance was observed by use

chitosan solution, showing permeability enhancement epithelium [145].

30 min afteprotect the delivery is aEstradiol thability throweight of ctosan (222molecular w70% cell viachitosan is uable physicnano carrie

All of threlief from it is unbiaseness of antiestablished

6. Regulat

Chitosantive by regEngland. Inmaceutical 14), http://dx.doi.org/10.1016/j.ijbiomac.2014.08.052

es can reach to brain [146151]. Among which, olfac-igeminal nerve pathway originating in the brain and

in the nasal cavity provide opportunity to deliver agents directly to central nervous system, represent-st persistent route in terms of non-invasive and directery of nanoparticles, [151,152] which can bypass BBBd in Fig. 5. Fazil et al. [101] reported three fold higheron of Rivastigmine in the brain after intranasal deliv-parison of I.V. administration, on the basis of confocaling microscopy and rhodamine-123 as a marker. Drugaded in nanocarriers like PLA provides more than 1.5e in brain accumulation of intranasal administered pep-hen nanocarrier is coated with chitosan. Vaka et al.ted ability of carnosic acid loaded chitosan nanopar-ated up regulation of nuerotrophins. This study draws

the requirement of lesser dosage, frequency of drugosan nanocarrier in comparison of IV injection of aain therapeutic goal due to the efciency of chitosanggregate in the olfactory mucosal region after intranistration. In a separate study, concentration of estra-o observed to be higher in CSF and lower in blood afterdministration of chitosan-estradiol nanoparticles [106].l. [154] and Shah et al. [155] concluded in their workrticles with only less than 100 nm in size can undergoonal transport otherwise chitosan particles get trans-rain via a transcellular pathway because of adhesionitosan nanoparticles and extracellular mucus. Simi-mulsion with globule size of less than 60 nm exhibitsiveness, high diffusion coefcient and remain devoid ofcity.intranasal are preferred route for delivery of therapeu-ntaining nanocarrier to the affected parts of the brain in

oral route is frequently explored with various nanocar-S drug delivery. Latasa et al. [156] prepared QAPGC

ammonium palmitoyl glycol chitosan) nanoparticles of therapeutic peptide to the brain. They identiedrug was able to reach in systemic circulation and brainr oral administration. Additionally, QAPDC was able topeptide from enzymatic degradation in GIT. GIT to brainpparently evident by high permeability of chitosan andrough Caco-2 cell lines. It was observed that perme-ugh colon cells is lowered when decrease in molecularhitosan. In a similar study, high molecular weight chi-30 kDa) showed more cell toxicity in comparison of loweight (3.813 kDa) chitosan, demonstrating less than

bility at the end of the study when the former type of thesed [157]. Thus, it is critical to select chitosan with suit-

al property in preparation of anti-Alzheimer containingr to be delivered by oral route.e drugs summarized above have efcacy to providepathological and symptomatic conditions of AD. Henced to say that chitosan nanoparticles alleviate effective--AD drugs in non-invasive approaches also against well

IV administration approach of brain targeting.

ory aspects

is approved as a dietary supplement and food addi-ulatory agencies of the USA, Japan, Italy, Portugal and

spite of several evidences of its safety as a phar-ingredient [158], chitosan is yet to be approved as a

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Please cite this article in press as: J. Sarvaiya, Y.K. Agrawal, Int. J. Biol. Macromol. (2014), http://dx.doi.org/10.1016/j.ijbiomac.2014.08.052


Fig. 5. Popular routes of administration and transport pathways of brain targeted chitosan nanoparticles: (A) Intranasal route and (B) I.V. route.

Table 2List of patents featuring chitosan as a nanocarrier material for delivery of drugs with anti-Alzheimer activities.

Therapeuticagent studied

Nanocarrier design Prominent features of invention Patent application number

Statins Nanoemulsion (I.N.) forinhalation; Chitosan-StatinConjugation via amide linkage

Requires less than half of the drugthan oral and IV route

WO2014028587 A1

Nucleic acid TMC-PEG graft co-polymermicelles with RVG as ligand

Acetylcholine receptor mediatedtransfection of SiRNA to neuro-2acells achieved.

CN103182087A

siRNA Nanocomplex by ionic pairingof siRNA and chitosan

Nanoplex able to preventneurobrillary tangle formation bystreamlining tau functioning

US20120315322A1

Alzheimers diseasediagnostic agents

PLGA core enveloped by TMCforming core-shellnanoparticle

Chitosan and its derivativesstabilized nanospheres fromaggregation. Use of air bubble asdetection enhancing substance.

US8449915 B1

Hydralazine Chitosan-TPP andChitosanDextran sulphatenanoparticles

Drug loading is signicantly high indextran sulphate crosslinkednanoparticles than TPP crosslinkednanoparticles

US20110052713 A1

Drugs for CNS Diversed nano carrier systems Transferrin, insulin, Insulin likegrowth factor and polysorbate-80combinations as ligands. Patentsfor degree of acetylation and lowmolecular weight of carrier system

US20060051423 A1

Various hydrophobic drugs Chitosan-poly--glutamic acidconjugates forming micelles

Trehalose as cryoprotectant informulation and chitosan aspermeation enhancer.

US7879313 B1

Leucine-Enkephalin Quarternary palmitoyl glycolchitosan micelles

Use of cholesterol, stearic acid,myristic, lauric. Capric, palmiticacid as linker for hydrophilic drug

WO2010100479 A1

Curcumin Modied chitosannanoparticles

Chemical modication withrepetitive heating and cooling ofchitosan suspension

CA2732635 A1

Anti-inammatory agent Chitosan salt-Hyaluronic acidnanoparticle by ionic gelationmethod

-Use of chitosan chloride orglutamate salts in preparation ofnanoparticles. Zeta potential valuenear 1mv.

US20140038894 A1

Proteins, drugs, genes Chitosan reverse micellescoated by crosslinkers whichcan bind to divalent metal

Divalent metal like Mg acceleratesnose to brain delivery of CNS drugcontaining chitosan nanocarrier.

WO2013040295 A2

Please cite l. (20


pharmaceutical excipient due to its non utility in new productswhich are under regulatory approval process. Clinical trial advance-ment of GalNac (N-acetyla galactosamine) complexed siRNA andchitosan carrier entrapped insulin delivery to brain for Alzheimersdisease treapproval apauthorities and nasal drinventors innanocarrier

7. Conclus

Use of chsesses highdrugs to thedation prodon numeroutive efcacytargeting. Spatibility amodicatiodrug delivethat enhancbrain directunits. Feasiits derivatiAlzheimerssuitable nadelivery duties and pro

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atment has encouraged possibility of its commercialplication in the future, which may insist regulatoryto consider chitosan as a safe excipient in parenteralug delivery. Intellectual properties claimed by different

the context of application of chitosan in brain targeted containing anti-Alzheimer drugs are listed in Table 2.

ion

itosan and its derivatives as a nanocarrier material pos- end result expectations in delivery of anti-Alzheimer

brain. Multiple bioactivities of chitosan and its degra-ucts itself supports neuroprotective activities by actings biomolecules present in the brain. Further, the proac-

of chitosan to cross BBB also favors its selection in brainufcient evidences are available for chitosan hemocom-nd biocompatibility enhancement by various surfacen approaches for its application in parenteral and nasalry with view of brain targeting. It was also revealeded expression of several biomolecules in AD affectedly and indirectly linked with bioactivities of chitosanbility of different ligands to bind with chitosan andves also allows targeting of neuronal cells in case of

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