Gold Nanoparticles as Theranostic Delivery System in Combating Various Diseases

This chapter is mainly focused on gold nanoparticles (AuNPs), along with their mechanism of actions, bio-distribution, pharmacokinetics, toxicities, host-immune response, and their potential bio-medical applications against a lot of diseases. Due to the increase in diseases brought on by toxicants and infectious microorganisms, it is needed to create a theranostic delivery system based on targeted nanotechnology to treat particular ailments. Conventional anti-microbial, anti-carcinogenic, anti-atherosclerotic, and anti-endocarditic therapies have been used to treat a variety of diseases, but these therapies have been linked to the development of multi-drug resistance (MDR), significant toxic side effects, insufficient therapeutic indices, and limited drug bioavailability. In this concern, site-specific theranostic delivery may be an important arena of research to enhance drug-efficacy and reduce adverse side effects to host cells, while anti-microbial, anti-carcinogenic, anti-atherosclerotic and anti-endocarditic nanosized gold materials have emerged as potent diagnostic and therapeutic delivery system against various diseases due to their unique size, shape and surface -dependent physico-chemical, optical, photo-thermal, photodynamic, radio-sensitizing and surface plasmon resonance properties, ease of surface modification and high surface-to-volume ratio -associated active functional groups, bio-compatibility, facile synthesis, and stable nature. AuNPs, as nanotheranostics, may be applied for a synergy of diagnostics and therapeutics, owing to their optical and surface plasmon resonance characteristics, ease of synthesis, controllable size and shape, colloidal stability and tunable surface chemistry for achieving conjugation with biological moieties, accompanied by cargos-delivery, photo-imaging and photo-thermal therapy. The chapter also explores on the development of non-toxic and non-immunogenic AuNPs-coated cargos and ligands such as chitosan, polyethylene glycol (PEG) / polyethylene imine (PEI) with / without sugars, peptides, proteins, antibodies and genes as theranostic delivery carrier as well as system for targeting small molecules and theranostics to diseased sites through their ease of penetration, accumulation and release.