Chitin is the most abundant natural amino polysaccharide and is estimated to be produced annually almost as much as cellulose. It has become of great interest not only as an underutilized resource, but also as a new functional material of high potential in various fields, and recent progress in chitin chemistry is quite noteworthy. The purpose of this review is to take a closer look at chitin and chitosan applications. Based on current research and existing products, some new and futuristic approaches in this fascinating area are thoroughly discussed.

A review of chitin and chitosan applications

Biodegradable polymeric nanoparticles as drug delivery devices

Nanoparticles: Properties, applications and toxicities

Biodegradable polymeric nanoparticles based drug delivery systems

Improving drug solubility for oral delivery using solid dispersions.

Hydrophilic nanoparticulate carriers have important potential applications for the administration of therapeutic molecules. The recently developed hydrophobic-hydrophilic carriers require the use of organic solvents for their preparation and have a limited protein-loading capacity. To address these limitations a new approach for the preparation of nanoparticles made solely of hydrophilic polymers is presented. The preparation technique, based on an ionic gelation process, is extremely mild and involves the mixture of two aqueous phases at room temperature. One phase contains the polysaccharide chitosan (CS) and a diblock copolymer of ethylene oxide and propylene oxide (PEO-PPO) and, the other, contains the polyanion sodium tripolyphosphate (TPP). Size (200–1000 nm) and zeta potential (between +20 mV and +60 mV) of nanoparticles can be conveniently modulated by varying the ratio CS/PEO-PPO. Furthermore, using bovine serum albumin (BSA) as a model protein it was shown that these new nanoparticles have a great protein loading capacity (entrapment efficiency up to 80% of the protein) and provide a continuous release of the entrapped protein for up to 1 week. © 1997 John Wiley & Sons, Inc.

Novel hydrophilic chitosan-polyethylene oxide nanoparticles as protein carriers

Design of microencapsulated chitosan microspheres for colonic drug delivery.

Development of biodegradable microspheres and nanospheres for the controlled release of cyclosporin A

— The main objective of this paper was to investigate the ability of polycyanoacrylate nanoparticles to improve the corneal penetration of hydrophilic drugs. Three different nanoparticle formulations were prepared by changing the nature of the stabilizer agent (Dextran 70000, Synperonic F 68 and sodium lauryl sulphate). The significant influence of the stabilizer type on the particle size, electrophoretic mobility and on the drug loading efficiency was proved. Moreover, the ocular disposition of amikacin was affected by its association to nanoparticles, displaying the most interesting results when Dextran 70000 was employed for preparation of nanoparticles. The increase of the amikacin concentration in cornea and aqueous humour was statistically significant for this nanoparticle formulation with respect to the other formulations and the control solution. The in-vitro release profiles obtained using a dialysis system were similar for all the nanoparticle formulations and for the control solution, indicating that drug molecules are desorbed from the nanoparticles quickly enough to maintain the equilibrium concentration in the dialysis system.

Improvement of ocular penetration of amikacin sulphate by association to poly(butylcyanoacrylate) nanoparticles.

L'objectif de ce travail a ete de mettre au point une formule lyophilisee de nanoparticules de chitosane chargee en insuline et d'evaluer son efficacite dans la reduction des taux de glucose plasmatique apres administration nasale. Les nanoparticules de chitosane ont ete preparees par gelification ionotrope de chitosane avec des anions tripolyphosphate, puis caracterisees in vitro (taille, potentiel zeta, charge en insuline et liberation) et in vivo (taux de glucose plasmatique). Les nanoparticules ont aussi ete lyophilisees en presence de differents agents cryoprotecteurs puis etudiees apres reconstitution dans l'eau. Les nanoparticules fraiches de chitosane ont une charge positive et une charge en insuline elevee (jusqu'a 55% m/m). Les etudes de liberation in vitro ont montre que l'insuline etait totalement liberee a partir des nanoparticules en moins d'une heure. Apres lyophilisation en presence de trehalose ou de saccharose, les nanoparticules ont ete rapidement reconstituees dans de l'eau sans changement significatif de leur taille, potentiel zeta, charge en insuline et liberation. L'evaluation in vitro chez le lapin a montre que les nanoparticules chargees d'insuline permettaient de reduire les taux plasmatiques de glucose de maniere plus marquee que les solutions d'insuline et chitosane. De plus, l'efficacite in vivo des nanoparticules chargees d'insuline reconstituees administrees par voie nasale etait completementmaintenue. Par consequent, des particulesde chitosane peuvent etre proposees comme transporteurs utiles pour augmenter l'absorption nasale de l'insuline.

J. L. Vila-Jato

Papers

Novel hydrophilic chitosan-polyethylene oxide nanoparticles as protein carriers

Design of microencapsulated chitosan microspheres for colonic drug delivery.

Development of biodegradable microspheres and nanospheres for the controlled release of cyclosporin A

Improvement of ocular penetration of amikacin sulphate by association to poly(butylcyanoacrylate) nanoparticles.

Development of a freeze-dried formulation of insulin-loaded chitosan nanoparticles intended for nasal administration