Current Expansion of Silver and Gold Nanomaterials towards Cancer Theranostics: Development of Therapeutics

Abstract

Nanomaterial-based therapeutics is an emerging tool for the treatment of numerous types of cancer. Various types of polymeric, lipid and inorganic nanoparticles (NPs) result in a wider series of applications in cancer diagnosis and therapeutics. The NPs properties are due to high surface area to volume ratio, surface plasmon resonance, absorption in the visible spectrum and light scattering. These unique characteristics of NPs arise due to their optical surface properties for conjugation/surface modification and smaller size. In cancer therapeutics, NPs based products are used as a biomarker for early detection/diagnosis of tumours, drug nano-conjugates for the delivery of chemotherapeutic drugs to the tumour-specific site, chemo-protective agents, etc. Furthermore, other advantages of NPs are biocompatibility, lesser toxicity, enhanced permeability and retention effect, higher stability, and specific targeting with a selective accumulation of nano drugs in the tissue of the tumour. The selective targeting of NPs to tumour tissue is possible by adding surface-active targeting agents i.e., antibodies. The selective transport of drug NPs conjugates to the cancer cells is increased and extravagated due to permeable vasculature from endothelial cells gap while failing the transport of drug NPs conjugates in normal cells. This review emphasizes metallic NPs, including silver NPs (AgNPs) and gold NPs (AuNPs), which are extensively reconnoitered in various applications in cellular targeting, imaging, drug delivery, DNA-NPs conjugates for biosensor/point of care devices development, photothermal/photodynamic therapy, protein-protein interaction, etc. In addition, this review discussed different synthetic methods of AgNPs and AuNPs and characterization methods. Furthermore, it highlighted the different properties and applications of AgNPs and AuNPs in cancer theranostics.