NANOPARTICLES BASED ON STAR-SHAPED CARBOXY-TERMINATED POLYLACTIDE AND

CHITOSAN FOR CONTROLLED RELEASE APPLICATIONS

Antonio Di MartinoCentre of polymer systems

dimartino@ft.utb.cz

Drug Delivery Systems (DDS)Drug delivery systems : approaches, formulations, technologies for the targeted delivery and/or controlled release of therapeutic agents

Safe Perform therapeutic function Convenient administration Ease of manufacturing

Bioactive Molecules 

Vincristine

Progesterone

Antibiotics

Steroids

Antineoplastics

Paclitaxel Doxorubicin

Testosterone

Amoxicillin Sultamicillin Methicillin

Estradiol

Burst EffectLarge amount of drug released immediately upon placement in the media

Journal of Controlled Release 73 (2001) 121 –136

Advantages Wound treatment Targeted delivery (triggered burst release) Pulsatile release

Disadvantages Local or systemic toxicity In vivo short t1/2 Waste of drug Short release profile Frequent administration Difficult to predict intensity

Burst Effect

Surface extraction

Drug loading distribution

Surface modification

Polymer morphology and composition

• preparation steps • cost

Process conditions Surface characteristics Morphology Carrier-Drug interactions

Causes

How to reduce….

Chitosan (CS) Biocompatibility Biodegradability Not toxic Not immunogenic Chemical modification Soluble in mild acidic aqueous media Well known behavior

Glucosamin

N-Acetyl glucosamin

chemotherapy drug Anthracycline antibiotic DNA intercalant  Widely used Side effects

Doxorubicin (DOX)

CS modification by grafting Star Shaped carboxy terminated Poly Lactic Acid (SSPLA)

Reduction of Burst Intensity

Methods

SSPLA synthesis

O

OH

N

O

OH

N

O

OH

N

O

OH

OOH

CHCH3

OOH

O

O

N

O

O

N

O

O

N

O

O

OO

CH3

OOH

CH3

O

OHCH3

OH

O

CH3

O

OH

+ lactic a cid , M SA

130°C, vacuum

main product: star shaped poly(lactic acid)

a

b

c

d

e

-(a+b+c+d+e+n)H2O

• Polycondensation reaction

• Pentetic acid as core molecule

• Methansulfonic acid as catalyst

• Coupling reaction

CS-SSPLA

EDC, NHS

48h , RT+

CS

SSPLA CS-SSPLA

CS-SSPLA NPs preparation PolyElectrolytes Complexation method

Dextran sulfate (DS, Mw 40 kDa)

CS-SSPLA / DS (w/w): 2

1 mg DOX

Fast Low cost Solvent free NPs size related to the polymers weight ratio

DS

CS-SSPLA

DOX

+

I. Add DS + DOX solution

DS

DOX

CS-SSPLA

II. 30 min stirring , RT

Encapsulation Efficiency (EE) & Release kinetic

100DDD(%)EEt

ft

Encapsulation and Release were evaluated by UV-Vis at 480nm

Phosphate Buffer (PBS) : pH 7.4 Preparation Media (PM) : pH 5 Simulated Gastric Fluid (SGF): pH 1.8 Temperature : 37 ˚C 180 rpm shake

Dt = amount of DOX added (mg/ml) Df = amount of DOX free after encapsulation (mg/ml)

Release conditions

Encapsulation

SSPLA and CS-SSPLA SSPLA

CS-SSPLA

Mn = 1900 g/molMw = 4000 g/molMw/Mn = 2.4

GPC

H- NMR (-COOH/-OH ratio) = I 5.01/ I 4.2 = 3.45

CCOOH = 0.979 mmol/g

FTIR-ATR = presence of amide bond

1H-NMR

NPs characterization and Encapsulation

Efficiency

+ 30% - 30%

Average dimension < 200 nm z-potential : 20-35 mV Dimension increases 12-18% after 1 month storage

EE > 80% 200-220 mg DOX/mg carrier SSPLA side chain increase EE

s p2 = 8.23s p

2 =12.62 sp2 =1.92 sp

2 =2.06

+ 8%

sp2 = 30.25

DOX Release kineticsCS CS-SSPLA

pH Swelling SSPLA

Release rate

SSPLA Does not significantly influence the swelling

DOX Release kinetics

pH SSPLA

Burst Intensity ( reduction up to 100 % compare to CS )

Lag time (1 – 3 h)

Conclusions Nanoparticles dimension < 200 nm

Nanoparticles are stable up to 1 month at room temperature

DOX EE > 80 %

The presence of SSPLA side chain increase 8% EE

Lag time from 1-3 h according with pH

Reduction of Burst Intensity in all media

Future Perspectives Multi-drug encapsulation

Combination of hydrophilic and hydrophobic drugs

Peptides or proteins

Optimization of release profile according with therapeutic goals