Polymeric and metallic nanoparticles as carriers in biomedical applications

Abstract

Nanoparticle mediated delivery of biomolecules has attracted interest of the researchers working in the area of gene therapy. Nanoparticles being small and compact are well suited to traverse cellular membranes to mediate drug or gene delivery. It is also expected that due to their smaller size, nanoparticles will be less vulnerable to reticuloendothelial system clearance and will have better penetration into tissues and cells, when used in in vivo therapy. Gene therapy has been proposed as a potential strategy for curing cancer, neurodegenerative disorders, infectious as well as genetic diseases such as tuberculosis, asthma, cystic fibrosis, dystrophies, hemophilia, etc. The principle of gene therapy is, not only to replace a potentially deficient gene but also, and more importantly, to influence the physiology and signal transduction in the cell by overexpressing or down-regulating one or several genes. Down-regulation of a gene can be achieved by the transfer of short antisense oligonucleotides (ODNs) into cells or by intracellular delivery of the more recently developed small interfering RNA (siRNA). In addition, a gene can be expressed by translocating plasmid DNA into cells containing the sequence for a gene of interest under the influence of a promotor. The vectors for delivering nucleic acids (ODNs, siRNA or plasmid DNA) to the cells by physical means or using specific carriers that transfer genetic material into the nucleus of the cells for gene expression. Among the various methods developed for delivering genes, gene carriers have been widely explored for transfection into mammalian cells. Generally, gene carriers are divided into two main groups: viral carriers, where the DNA to be delivered is inserted into a virus, and non-viral carriers, where the DNA is delivered in the form of a complex formed between a vector and DNA. Viral delivery systems involve genetically engineered recombinant viruses that carry therapeutic gene in their viral capsid, thus protecting it from enzymatic degradation.