Targeted mucosal delivery of drugs and vaccines

Nanochitosan: Commemorating the Metamorphosis of an ExoSkeletal Waste to a Versatile Nutraceutical

Chitin (poly-N-acetyl-D-glucosamine) is the second (after cellulose) most abundant organic polymer. In its deacetylated form-chitosan-becomes a very interesting material for medical use. The chitosan nano-structures whose preparation is described in this article shows unique biomedical value. The preparation of nanochitosan, as well as the most vital biomedical applications (antitumor, drug delivery and other medical uses), have been discussed in this review. The challenges confronting the progress of nanochitosan from benchtop to bedside clinical settings have been evaluated. The need for inclusion of nano aspects into chitosan research, with improvisation from nanotechnological inputs has been prescribed for breaking down the limitations. Future perspectives of nanochitosan and the challenges facing nanochitosan applications and the areas needing research focus have been highlighted.

Chitosan-based nanoparticles as drug delivery systems: a review on two decades of research

Chitosan (CS) is one of the most functional natural biopolymer widely used in the pharmaceutical field due to its biocompatibility and biodegradability. These privileges lead to its application in the synthesis of nanoparticles for the drug during the last two decades. This article gives rise to a general review of the different chitosan nanoparticles (CSNPs) preparation techniques: Ionic gelation, emulsion cross-linking, spray-drying, emulsion-droplet coalescence method, nanoprecipitation, reverse micellar method, desolvation method, modified ionic gelation with radial polymerisation and emulsion solvent diffusion, from the point of view of the methodological and mechanistic aspects involved. The physicochemical behaviour of CSNPs including drug loading, drug release, particles size, zeta potential and stability are briefly discussed. This review also directs to bring an outline of the major applications of CSNPs in drug delivery according to drug and route of administration. Finally, derivatives of CSNPs and CS nano-complexes are also discussed.

The lectin-cell interaction and its implications to intestinal lectin-mediated drug delivery

Based on the fact that oligosaccharides encode biological information, the biorecognition between lectinised drug delivery systems and glycosylated structures in the intestine can be exploited for improved peroral therapy. Basic research revealed that some lectins can mediate mucoadhesion, cytoadhesion, and cytoinvasion of drugs. Entering the vesicular pathway by receptor mediated endocytosis, part of the conjugated drug is accumulated within the lysosomes. Additionally, part of the drug is supposed to be transported across the epithelium. Moreover, factors probably adversely influencing feasibility of the concept such as toxicity, immunogenicity, and intestinal stability of plant lectins are discussed. As exemplified by lectin-grafted prodrug and carrier systems, this strategy is expected to improve absorption and probably bioavailability of poorly absorbable drugs, peptides and proteins as well as therapeutic DNA.

Lectin-mediated drug delivery: binding and uptake of BSA-WGA conjugates using the Caco-2 model

To examine whether the dietary lectin wheat germ agglutinin (WGA) can facilitate binding and uptake of protein drugs due to its cytoadhesive and cytoinvasive properties, conjugates were prepared by covalent coupling of fluorescein-labeled bovine serum albumin (F-BSA) to WGA using divinylsulfone for crosslinking. Increasing the molar ratio of F-BSA/WGA resulted in 2.6-8.7 times higher Caco-2 binding as compared with glycyl-F-BSA. About 75% of F-BSA-WGA were bound specifically to Caco-2 cells according to inhibition studies in presence of the complementary carbohydrate. The Caco-2 association of F-BSA-WGA was temperature-dependent indicating active uptake of membrane bound conjugate, which was confirmed by confocal microscopy. The conjugate accumulated within lysosomal compartments followed by proteolytic degradation of F-BSA-WGA 1-4 h after conjugate loading as observed by equilibrating the intracellular pH with monensin. Finally low molecular weight degradation products of the proteinaceous prodrug appear in the extracellular medium. Contrary to Caco-2 single cells, a minor part of the conjugate is degraded by brush border proteases already 30 min after exposure to Caco-2 monolayers. But most of the conjugate is taken up into differentiated cells and processed as in single cells. Though the enzymic barrier remains to be surmounted, WGA-mediated drug delivery is a promising strategy for peroral delivery of even high molecular weight drugs to overcome the mucosal barrier.