Recent Biomedical Approaches for Chitosan Based Materials as Drug Delivery Nanocarriers.

In recent decades, drug delivery systems (DDSs) based on nanotechnology have been attracting substantial interest in the pharmaceutical field, especially those developed based on natural polymers such as chitosan, cellulose, starch, collagen, gelatin, alginate and elastin. Nanomaterials based on chitosan (CS) or chitosan derivatives are broadly investigated as promising nanocarriers due to their biodegradability, good biocompatibility, non-toxicity, low immunogenicity, great versatility and beneficial biological effects. CS, either alone or as composites, are suitable substrates in the fabrication of different types of products like hydrogels, membranes, beads, porous foams, nanoparticles, in-situ gel, microparticles, sponges and nanofibers/scaffolds. Currently, the CS based nanocarriers are intensely studied as controlled and targeted drug release systems for different drugs (anti-inflammatory, antibiotic, anticancer etc.) as well as for proteins/peptides, growth factors, vaccines, small DNA (DNAs) and short interfering RNA (siRNA). This review targets the latest biomedical approaches for CS based nanocarriers such as nanoparticles (NPs) nanofibers (NFs), nanogels (NGs) and chitosan coated liposomes (LPs) and their potential applications for medical and pharmaceutical fields. The advantages and challenges of reviewed CS based nanocarriers for different routes of administration (oral, transmucosal, pulmonary and transdermal) with reference to classical formulations are also emphasized.

[Antisense oligonucleotides with pharmacologic action]. / Oligonucleotide antisens cu activitate farmacologica.

The potential therapeutic applications of the antisense strategy are illustrated by numerous examples of the oligonucleotides investigated in preclinical and clinical trials especially for antiviral, antiinflammatory, anticancer and antiatherosclerotic activity. The main advantages of the antisense oligonucleotides therapeutic candidates are comparatively discussed with the classical drugs.

[Basic principles of the antisense strategy]. / Principii fundamentale ale strategiei antisens.

The antisens strategy is based on specific inhibition of the mutant gene expression by oligodeoxynucleotides (OGN), capable of selectively hybridizing with target DNA or RNA. Molecular mechanisms of the antisense oligonucleotide comprise: inhibition of splicing, inhibition of 5'-capping and 3'-polyadenylation, activation of RN-ase H, small interfering RNA, ribozymes. The antisense strategy is applied to: rational design of potent, selective therapeutic agents, target validation and detection of pathologic gene expression in vivo. The main aim of the antisense oligonucleotide design is to improve the affinity for target RNA and the resistance to nucleolytic degradation.