Biogenic Gold Nanoparticles (AuNPs) and its Biomedical application - Current & Future Prospects

Review Article

Austin J Anal Pharm Chem. 2023; 10(3): 1163.

Biogenic Gold Nanoparticles (AuNPs) and its Biomedical application - Current & Future Prospects

Karishma Niveria¹; Priyanka Singh¹; Largee Biswas¹; Monika Yadav¹; Kapil Dangi¹; NK Prasanna³; Kapinder Kumar4; Anita Kamra Verma1,2*

1Nanobiotech Lab, Department of Zoology, Kirori Mal College, University of Delhi, India

2Fellow, Delhi School of Public Health, Institution of Eminence, University of Delhi, India

3CSIR-National Institute of Science Communication and Policy Research, India

4Department of Zoology, Allahabad University, India

*Corresponding author: Anita Kamra Verma Nanobiotech Lab, Department of Zoology, Kirori Mal College, University of Delhi, India. Email: akverma@kmc.du.ac.in

Received: October 31, 2023 Accepted: December 04, 2023 Published: December 11, 2023

Abstract

Green nanotechnology offers immense opportunities as it applies principles of green chemistry for synthesis of nanomaterial for various applications. Green gold nanoparticles (AuNPs) provide eco-friendly materials at low cost and toxicity, high chemical and thermal stability, enhanced degradation activity for environmental remediation and used in numerous biomedical fields. For biomedical application, the toxic chemical agents used for synthesis via conventional methods are a major deterrent. To address this, green synthesized of gold nanoparticles (AuNPs) were extensively studied. Continuous efforts have been focused on facile, low cost, pure, non-toxic and environment friendly approach for their synthesis. Their biocompatibility, photonic properties and their possible solubility in aqueous phases enabled the assimilation of AuNPs in diverse biomedical field. Different biological resources normally existing in the environment have been used for biosynthesis of biogenic nanoparticles that include bacteria, fungi, algae, yeast, cyanobacteria, actinomycetes, viruses and plants This review provides a comprehensive overview of synthesis and characterization of biogenic AuNPs with their broad applications in biomedical fields have also been elucidated along with their future prospects.

Keywords: Biogenic synthesis; Gold nanoparticles; Anti-bacterial activity; Biomedical applications

Abbreviations: NPs: Nanoparticles; nm: Nanometer; sp.: Species; EPS: Exopolysaccharides; DNA & RNA: Deoxy-Ribonucleic Acid/ Ribonucleic Acid; UV-vis: UV-Visible Spectroscopy; XRD: X-ray diffraction; FTIR: Fourier Transform Infrared Spectroscopy; GCMS: Gas Chromatography-Mass Spectrometry; HPLC: High Performance Liquid Chromatography; EDS: Energy Dispersive Spectroscopy; DLS: Dynamic Light Scattering; SEM: Scanning Electron Microscopy; TEM: Transmission Electron Microscopy; AFM: Atomic Force Microscopy; SPR: Surface Plasmon Resonance; ZP: Zeta Potentials; mV: Milli Volts; SAED: Selected Area Electron Diffraction; pH: Potential of Hydrogen; ROS: Reactive Oxygen Species; MIC: Minimum Inhibitory Conc.; CFU: Colony Forming Unit; LPS: Lipopolysaccharides; JAK/STAT: Janus Kinase/Signal Transducers And Activators of Transcription; NF-kB: Nuclear Factor Kappa-Light-Chain-Enhancer of Activated B Cells; GFP: Green Fluorescent Protein; RME: Receptor-Mediated Endocytosis; MRI: Magnetic Resonance Imaging; CT scan: Computer Tomography Scan; LOD: Limit of Detection; LOQ: Limit of Quantification

Introduction

Nano-science and technology is the new-fangled approach that becomes an inexorable element of the modern Era and are still garnering considerable interest in witnessing the ease of technology at the scientific and commercial level. The small-dimensions nanoparticles (1–100 nm) govern the entire research globally, due to its remarkable applications in physical, chemical, environmental and biological sciences [1]. Among all the synthetically classified nanoparticles, metal-based nanoparticles have enraptured, due to their unique physicochemical characteristics, highly active, reproducibility and antibacterial properties attributed to their enormous surface area to volume ratio [2,3]. Metallic nanoparticles that have achieved immense attention recently due to their imperative significance are aluminium, silver, gold, iron, zinc, copper and palladium [4]. Specifically, gold nanoparticles have an extensive history for medical purpose such as management of various aliments due to their biocompatible nature, high thermal and electrical conductivity, surface-enhanced Raman scattering, chemical stability, catalytic activity and antimicrobial activity [5]. The characteristics of metal nanoparticles contribute to several biomedical purposes assisted by optical device, sensing components, photothermal therapy, catalysts and targeted drug delivery [2]. There are various studies that described the different mode of gold NPs formulation- include chemical, radiation, electrochemical, Langmuir-Blodgett, photochemical methods and biological techniques. Generally, conventional mode of synthesis has serious limitations like as upfront use of toxic reagents that are extremely harmful for the living system and environment, high cost, exposure to radiation, requires high-energy input, high temperature and less productivity. The chemical diluters used during fabrication later on leads to troubles in nanoparticles extraction and also exhibit considerable obstacles to biomedical applications. Furthermore, during the application of gold nanoparticles as drug delivery carriers the extra of precursor constituents may causes cytotoxicity of healthy cells. Some reports states that function of heart and its vasculature can be affected by AuNPs that have to be cautiously evaluated [6]. Therefore, there is an emergent need to develop an environmentally benign method for the gold nanoparticles synthesis. This draws attention to the researchers and industrial sector in the field of nanoparticle synthesis and assembly to utilize some biocompatible natural compounds for the reduction of Au-containing salts for the synthesis of Au nanoparticles is very important, that further generate numerous imperative pharmaceutical molecules relevant for various biomedical applications as toxic substances are abolished [6,7]. The biogenic synthesis method has several advantages with respect to clean, cost effective, effortless procedure and eco-friendly approach. The use of various fungi, bacteria and plant tissues have been stated for the biosynthesis of gold nanoparticles. The biological mode of AuNPs synthesis is categorically classified into two approaches: first category involves the use of microorganisms such as- algae, bacteria, and fungi while the other is based on the plant-based extracts as reducing and stabilising agents [8,9]. The advantage of plant-based extract to serve as excellent reducing and stablishing agents are responsible in reducing particle size and enhance their reactivity in a one-pot synthesis of AuNPs. Here, we discuss the formulation of biogenic gold nanoparticles through green synthesis. The synthesis of green AuNPs is explained and various environmental parameters affecting their synthesis are introduced.

Collectively, this review highlights the recent trends in the fundamental processes and mechanisms of biogenic synthesis AuNPs by using various biological systems (plants, algae, bacteria, fungus and etc). Consequently, till date, no detailed analyses and comprehend of the rationale factors affecting the green synthesis of AuNPs and their characterization has been studied.Further, we exclusively update the context of various factors affecting the biogenic synthesis of AuNPs and different characterization techniques used to determine the physiochemical properties of synthesized NPs and offer a deep understanding of NPs and their potential biomedical application in modern technology and in green environmental technology. The imminent applications of green AuNPs in the biomedical fi eld involves anti-microbial agents, drug delivery agents, therapeutic agents, bio-sensing agents, and removal of environmental pollutants are also elaborated meticulously.

Mechanism Involved in the Biosynthesis of Gold Nanoparticles

In recent growing interest of industrial microbiology for green synthesis approach of nanoparticles with diverse range of microorganisms from bacteria, fungi, algae to actinomycetes, etc., has triggered the effective eco-friendly synthesis mechanism owing to vivid benefits such as effortless processing and management, reduced synthesis cost of medium for their growth, reduction and stabilisation ability of the biogenic compounds etc. known as main striking reasons for choosing biosynthesis as an alternative approach for nanoparticles synthesis. Here, Macro-scale cultivation in huge fermenters or on substrate (cellulosic wastes, agricultural wastes) will facilitate the surplus extraction of enzymes along with list of secondary metabolites in sustained way with least economical investment. For example, utilisation of such an inexpensive raw material will initiate cyclic waste management and drop down the increasing risk of environmental pollutants (heavy metals, dyes, and toxic chemicals etc.) too.

Fungal Based Green Synthesis Approach

Majority of fungal microorganism are known for their bio-active compounds that are obtained from them [10]. They are also known for their extreme tolerance, bioaccumulation and easy internalization of heavy metal ions from their surrounding nature. This allows us exploring edges where they can work as fungal nanofactories synthesizing desired nanoparticles with controlled size and morphology [10,11]. The underlying mechanism for synthesis of biogenic metallic nanoparticles using fungal species involves intracellular synthesis approach and extracellular synthesis approach. In intracellular synthesis approach the metal precursors, commonly known as primary metals are added in to the fungal culture where metal ions undergo sequential process. This sequential process has various events well described in Verticillium sp., initiating at electrostatic interaction of metal ion with fungal cell wall components [12], this enables easy entrapment of metal ion at interacting interface. Following this is enzyme linked synthesis of biogenic nanoparticles through bio reduction process of metal ions and its diffusion across fungal cell wall. The small sizes of nanoparticles so formed are difficult to isolate from fungal culture as they are synthesized within fungal species. This intracellular synthesis approach hereby has demerits as extraction cost added to the entire synthesis process, it involves chemical extraction, sequential centrifugation, filtration etc. in order to liberate the NPs in the required form, leaving behind the fungal debris [13,14]. Similarly extracellular synthesis approach involves many other methods such as presence of extracellular enzymatic reactions that are responsible for conversion of metal ions to their nanoparticles, presence of electron shuttle system doing the same in the presence of electrons i.e. acting as strong bioreducing agents [15]. Michaelis–Menten enzyme kinetics models, where the biological reduction of various metallic NP was initiated by the presence of protein having amino acid with -SH bonds with dehydrogenation process occurring when present amino acid reacts with metal precursor, further presence of such free amino acids are also responsible for capping and stabilization of nanoparticles thus adding advantage to the synthesis approach [16]. Soltani Nejad et al aimed to synthesis AuNPs using the extracellular approach in an endophytic fungus (Phoma sp.) that was isolated from peach trees (Prunus persica). Synthesized AuNPs has the nanosize range of 10–100 nm and absorbance peak were recorded at 526 nm. Further its application against other fungal species (R. solani) was also determined which confirms reduced formation of sclerotia by this species on increased concentration of nanoparticles [17]. Islam and coworkers have worked employing mycosynthesis method used for synthesis of Gold-selenide nanoparticles (AuSeNPs), using endophytic fungus Fusarium oxysporum at ambient condition. Hereby, AuSe NPs was reported to have a mean hydrodynamic nanoparticles size of 52 nm with crystalline nature. Further its anti-sporulant potency was also observed against the black fungal species (Aspergillus niger). Thus minimize risk associated with re-infection, providing its wide utilization in developing newer fungicide or drugs with low cost and abundant supply [18] (Table 1).