Bacteriogenic Platinum Nanoparticles for Application in Nanomedicine

Abstract

Nanoscale materials have recently gained wide attention due to their potential to revolutionize many technologies and industrial sectors, including information technology, homeland security, transportation, energy, food safety, environmental science, catalysis, photonics and medicine. Among various nanoparticles, platinum nanoparticles (PtNPs) are widely used for biomedical applications, including imaging, implants, photothermal therapy and drug delivery. Indeed, PtNPs possesses intrinsic antimicrobial, antioxidant, and anticancer properties. Also, due to their remarkable catalytic activity, they are able to reduce the intracellular reactive oxygen species (ROS) levels and impair the downstream pathways leading to inflammation. Various approaches, including both physical and chemical methods, are currently employed for synthesis of PtNPs. However, the use of hazardous reaction conditions and toxic chemicals in these processes poses a potential threat to the environment and severely compromise the biocompatibility of the nanoparticles. Hereby, increasing need for exploitation of novel routes for synthesis of PtNPs has led to development of biological fabrication using microbes, specifically bacteria. Herein, we present a most comprehensive report on biogenesis of PtNPs by several bacteria like Acinetobacter calcoaceticus, Desulfovibrio alaskensis, Escherichia coli, Shewanella algae, Plectonema boryanum, etc. An overview of the underlying mechanisms of both enzymatic and non-enzymatic methods of synthesis is included. Moreover, this review highlights the scope of developing optimized process to control the physicochemical properties, such as the nanoparticle surface chemistry, charge, size and shape, which, in turn, may affect their nanotoxicity and response at the biointerface for nanomedicine applications.

Keywords: bacteriogenic synthesis; biointerfaces; nanomedicine; platinum nanoparticles; surface characterization.

FIGURE 1

Various methods for synthesis of PtNPs.

FIGURE 2

Morphologies of bacteriogenic PtNPs. (A) SEM images of Pt-BCcm membrane obtained from K₂PtCl₄ solution at 10mM where inset scale bar represents 1 µm (Aritonang et al., 2014); (B) Representative electron micrographs of PtNPs produced by D . alaskensis G20 which are exported and found on the surface of the cell where inset scale bar represents 200 nm (Capeness et al., 2015); (C) TEM image of recovered bioPt NPs from 1% Pt EcMC4100 after NaOH, washing, and centrifugation treatment where inset scale bar represents 50 nm (Attard et al., 2012); TEM micrographs of whole mounts of partially recrystallized spherical PtNPs in cyanobacteria-PtCl₄° systems at (D) at 60°C and 14 days where inset scale bar represents 0.25 µm; (E) at 80°C and 21 days where inset scale bar represents 0.1 µm; (F) 100°C days and 28 days where inset scale bar represents 0.1 µm (Lengke et al., 2006).

FIGURE 3

Extracellular and intracellular bacterial synthesis of nanoparticles

FIGURE 4

Scope and various applications of bacteriogenic PtNPs.