Green nanotechnology—An innovative pathway towards biocompatible and medically relevant gold nanoparticles

Abstract

In this review, we focus on recent advances in green nanotechnology, providing details on reliable synthetic pathways towards biocompatible and medically relevant gold and radioactive gold nanoparticles. We cover a wide plethora of synthetic protocols that utilize green nanotechnology with in-depth understanding of what makes a green process green. In section 2, we provide full details on the intervention of green nanotechnology for the production of various functionalized gold nanoparticles (AuNPs). Section 3 focuses on various characterization tools to be used for the complete physicochemical, size and in vitro characterization of gold nanoparticles before translating them into potential in vivo applications. Section 4 focuses on the science and applications of gold nanoparticles in diagnostic imaging. Specifically, we have highlighted the importance of the chemistry and physics of gold nanoparticles for applications in a myriad of diagnostic imaging including X-ray contrast agents, in single photon emission computed tomography (SPECT) imaging, positron-emission tomography (PET) imaging, optical coherence tomography (OCT), fluorescence imaging, magnetic resonance imaging (MRI), in surface enhanced Raman spectroscopy (SERS), and in ultrasound (US) imaging. Section 5 discusses latest advances on gold nanoparticles in drug delivery, gold nanoparticles in photothermal therapy and radioactive gold nanoparticles in cancer therapy. In particular, we discuss green nanotechnological interventions on how the electron rich phytochemicals including epigallocatechin gallate (EGCG) from tea, mangiferin (MGF) from mango and allied phytochemicals can be utilized in their dual roles, as reducing agents as well as rendering tumor specificity due to their strong tumor cell receptor avidity—to produce tumor specific molecular imaging and therapy agents. We also discuss latest advances on the importance of gold nanoparticles in X-ray Therapy. Important aspects relating to systemic toxicity of gold nanoparticles and ways to mitigate toxicity issues for their effective implementation in biomedical sciences are also discussed in section 6. The topics covered are intended to answer questions including why we should use green processes and what is the role of nanomedicine in the domain of human health and hygiene. Most importantly, we provide critical analysis on the ubiquitous role of gold nanoparticles in nanomedicine.