Polymeric Chitosan-based Vesicles for Drug Delivery

Abstract

A simple carbohydrate polymer glycol chitosan (degree of polymerization 800 approx.) has been investigated for its ability to form polymeric vesicle drug carriers. The attachment of hydrophobic groups to glycol chitosan should yield an amphiphilic polymer capable of self-assembly into vesicles. Chitosan is used because the membrane-penetration enhancement of chitosan polymers offers the possibility of fabricating a drug delivery system suitable for the oral and intranasal administration of gut-labile molecules. Glycol chitosan modified by attachment of a strategic number of fatty acid pendant groups (11-16 mol%) assembles into unilamellar polymeric vesicles in the presence of cholesterol. These polymeric vesicles are found to be biocompatible and haemocompatible and capable of entrapping water-soluble drugs. By use of an ammonium sulphate gradient bleomycin (MW 1400), for example, can be efficiently loaded on to these polymeric vesicles to yield a bleomycin-to-polymer ratio of 0.5 units mg(-1). Previously polymers were thought to assemble into vesicles only if the polymer backbone was separated from the membrane-forming amphiphile by a hydrophilic side-arm spacer. The hydrophilic spacer was thought to be necessary to decouple the random motion of the polymer backbone from the ordered amphiphiles that make up the vesicle membrane. However, stable polymeric vesicles for use in drug delivery have been prepared from a modified carbohydrate polymer, palmitoyl glycol chitosan, without this specific architecture. These polymeric vesicles efficiently entrap water-soluble drugs.

A Review of the Biocompatibility of Implantable Devices: Current Challenges to Overcome Foreign Body Response

“…Specifically, the challenges used to overcome the functional loss of glucose sensors, restenosis after stent implantation, and calcification induced by implantable devices are discussed. chitosan, [20][21][22] alginate, 23 hyaluronan, 24 and dextran. 25,26 Commonly used synthetic polymers include poly(lactic acid)(PLA) and poly(lactic-co-glycolic acid)(PLGA), [27][28][29][30][31][32][33] poly(ethylene glycol)(PEG), 34-36 2-hydroxy ethyl methacrylate, 33 and poly(vinyl alcohol)(PVA).…”

Poly(allylamine) Magnetomicelles for Image Guided Drug Delivery

“…Commonly, poly(ethylenimine) [10], poly(allylamine) [11] and chitosan [12] backbones have been used in the formation of these macromolecules. Previous work has reported the promising potential of poly(allylamine) (PAA) grafted with cholesteryl and dansyl moieties to act as universal hydrophobic drug solubilizers [13].…”

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“…In our laboratories polymeric vesicles for drug delivery have been developed from a specially designed amphiphilic chitosan derivativepalmitoyl glycol chitosan (PGC) (4). While the passive targeting of anti-cancer phospholipid vesicles (liposomes) (5,6) and non-ionic surfactant vesicles (niosomes) (7) to solid tumours has been well documented, liposomes for gene delivery are predominantly passively targeted to the lung endothelium (8,9).…”