EFFECT OF POLYLACTIDE MOLECULAR WEIGHT ON DOXORUBICIN AND TEMOZOLOMIDE RELEASE FROM CHITOSAN-GRAFTED POLYLACTIDE NANOPARTICLES

Antonio Di Martino

dimartino@ft.utb.cz

Introduction

Drug Delivery

POLYMERS IN DRUG DELIVERY

Natural Synthetic

Chitosan

Low Immune Response

Biodegradability

Reactive groups

Introduction

Alginate

Biocompatibility

PEG

Gelatin PMMA

PLA

Co-polymer Synthesis

Chitosan Polylactide

CS-g-PLA

Good biological properties

Poor mechanical properties

Good mechanical properties

Incompatibility with cells and blood

Low Molecular Weight Chitosan with Deacetylation Degree (DD) 75-85%

Polylactide : 10 and 60 kDa Polycondensation reactionMethanesulfonic acid160˚C

Coupling Reaction

Ionotropic Gelation

CS-g-PLA Tripolyphosphate

1 mg/mL in PBS pH 7.4

1 mg/mL in CH3COOH pH 5.5

Stirring Room Temperature

Nanoparticles Preparation

Size-pot

Morphology

FTIR-ATR1H NMR

Morphology

Doxorubicin (DOX)

Temozolomide (TMZ)

Tripolyphosphate in PBS pH 7.4

DOX in CH3COOH(aq) pH 5.5

TMZ in CH3OH

CS-g-PLA in CH3COOH pH 3.5

• Size (nm)• -pot (%)• Encapsulation (%) • Release • TEM• Swelling Index

Encapsulation and Co-Encapsulation

Release Kinetic

T = 25˚C ; pH 3.5, 7.4 and 9

T = 37˚C ; pH 3.5, 7.4 and 9

Nanoparticles Preparation

Results: copolymer characterization

FTIR-ATR 1H-NMR

CS

CS-g-PLA

Tra

nsm

ittan

ce(%

)

1.3 and 1.4ppm methyl protons located at the terminal groups of the backbone

4.2 and 5.1 ppm terminal methenyl protons of the branched polylactide and repeats unit in the chain

1730 cm-1 carbonyl of ester bond

2100 cm-1 C-N strech more intense

Results : NPs characterizationCS-g-PLA 10kDa

CS-g-PLA 60kDa

pH 5.5

Results : NPs characterizationCS-g-PLA 10kDa

CS-g-PLA 60kDa

pH 7.4

Results : Encapsulation Efficiency

DOX TMZ pHPLA 10 kDa 53% 47% 3.5

42% 58% 7.4

64% 36% 9

PLA 60 kDa 54% 46% 3.5

41% 59% 7.4

55% 45% 9

100

t

ft

D

DDEE

• Dt = Total amount of drug (µg/mL)• Df = Amount of drug unloaded (µg/mL)

DOX Abs : 480 nm TMZ Abs : 325 nm

Encapsulation

Co-Encapsulation

Results: Swelling Index(SI)

100

d

ds

W

WWSI

Ws = average weight of swollen sample (g) Wd = average weight of dry samples (g)

Swelling properties influence Release Kinetic

Human Serum37˚C; 24h

CS

CS-g-PLA 10kDa

CS-g-PLA 60kDa

Results : Release Kinetic Buffer solutions : pH 3,5 -7.4-9 Temperature : 37 ˚C Moderate stirring : 400rpm

CS-g-PLA 10 kDa CS-g-PLA 60 kDa

1000

D

DDR

t Dt = amount of drug released at t time (µg)

D0 = amount of drug loaded (µg)

DOX Abs : 480 nm TMZ Abs : 325 nm

Results : Co-Release Kinetic

CS-g-PLA 10 kDa CS-g-PLA 60 kDa

Increasing pH of the medium the release rate rise

TMZ is released faster than DOX in CS-g-PLA 10kDa

CS-g-PLA 60kDa drugs are released almost simultaneously

Conclusions

Polylactide with different Mw was successfully grafted to chitosan backbone as confirmed by FTIR-ATR and 1H-NMR analysis

Size (150-350nm) and -potential (25-45mV) values indicate that nanoparticles own good stability in physiological like media at different temperature

CS-g-PLA show high encapsulation and co-encapsulation either acidic or neutral environment

Sustained release and co-release in physiological like environment (almost 2 weeks) in both formulations (CS-g-PLA 10kDa and CS-g-PLA 60kDa)

Modulation of the release rate modifying the pH of the medium

Thank you for your attention.