Biosynthesized Gold Nanoparticles: In Vivo Study of Near-Infrared Fluorescence (NIR)-Based Bio-imaging and Cell Labeling Applications

Abstract

Near infrared (NIR) fluorescence imaging is a striking imaging modality for biomedical and clinical applications due to its deep tissue penetration and low phototoxicity. The major issue with NIR dyes is their non-specific distribution and requirement of tagging with biomolecules for specific tissue localization. Till now, there have been no imaging agents available that can distribute into a specific organ without the need for targeted ligands, which remains as an unmet clinical need. In the present study, we demonstrate that the Zinnia elegans plant extract (abbreviated as ZE) assisted synthesis of highly biocompatible gold nanoparticles (AuZE), leading to their non-invasive bio-imaging applications in the NIR region (red at 820 nm emission: NIR region). AuZE and ZE both exhibited green fluorescence at 350 nm excitation and red fluorescence in the NIR region (710 nm). We verified the source of this fluorescence, which originates from the fluorescent molecules present in the ZE extract. After intraperitoneal administration in C57BL6 mice, very interestingly, AuZE is distributed into the brain of C57BL6 mice without the need for any targeted ligand and exhibited bright red fluorescence in the NIR region (710 nm excitation, 820 nm emission) as evidenced by non-invasive imaging as well as ICPOES techniques. We further explored the activity of ZE and AuZE as cell labeling agents (B16F10 cells were pre-incubated with AuZE and implanted into mice, and the fluorescence was monitored), which could be applicable for graft transplantation biology. To the best of our knowledge, this is the first report that demonstrates the versatile applications of green synthesized gold nanoparticles using a ZE extract. Considering these exciting results and fruitful outcomes, the ZE and AuZE NPs would stand as an alternative imaging agent to commercially available NIR dyes and change the conventional fluorescence-based bioimaging strategies. Therefore, the biosynthesized AuNPs open new directions for future research to explore these latest observations in the field of disease diagnosis and therapy.

Biosynthesized Silver Nanoparticles for Cancer Therapy and In Vivo Bioimaging

“…To this end, our group already reported biosynthesized gold nanoparticles (AuZE), obtained by the reduction of gold salts using extracts of Zinnia elegans , that exhibit fluorescence at both the green (emission: 450 nm; excitation: 350 nm) and red regions (emission: 720 nm; excitation: 450 nm). The AuZE when injected intraperitoneally in C57BL6/J mice exhibited non-invasive NIR bioimaging (excitation: 710 nm; emission: 820 nm) [ 29 ]. However, these gold nanoparticles do not exhibit anticancer activity unless we use any chemotherapeutic drug.…”

“…Considering the above fundamental issues and knowing the anticancer activity of silver from various published literature, we designed and developed silver nanoparticles (AgZE) using the leaf extract of Zinnia elegans (ZE). The Zinnia elegans plant has been selected for biosynthesis as it emits fluorescence in the NIR region as per the published literature [ 29 ]. Additionally, the ZE plant has several medicinal values such as hepatoprotective, antifungal, antihelmintic, antimalarial, anti-infective, phytoremediation, etc.…”

“…Additionally, the ZE plant has several medicinal values such as hepatoprotective, antifungal, antihelmintic, antimalarial, anti-infective, phytoremediation, etc. [ 29 , 30 , 31 ]. Our hypothesis is that, during synthesis, some of the bioactive molecules can attach to the surface of the nanomaterials that show some biological activity.…”

Biosynthesized Gold and Silver Nanoparticles in Cancer Theranostics

“…In other interesting investigation, Popovtzer and group demonstrated conjugation of citrate reduced gold nanoparticles with 2-deoxy-d-glucose, which aids in penetration and accumulation in tumor cells and can be used as a diagnostic imaging tool for imaging tumor cells (US 10,478,132) [58]. Kotcherlakota et al demonstrated the synthesis of biocompatible AuNPs using aqueous leaf extract of Zinnia elegans and their applications toward in vivo near-infrared fluorescence (NIR)-based bioimaging and cell labeling applications in mouse B16F10 melanoma tumor model [29].…”

Acute Toxicity, Biodistribution, and Pharmacokinetics Studies of Pegylated Platinum Nanoparticles in Mouse Model

“…[ 1–3 ] Among them, noble metal NPs (gold, silver, and platinum NPs [PtNPs]) offer promising opportunity for various biomedical applications, including drug delivery, bioimaging, diagnostics, etc., owing to their distinctive physicochemical properties. [ 4–8 ] However, serious toxicological consequences might be observed on interaction of these NPs with the biological moieties at cellular and subcellular level. Based on this, several studies investigated potential toxicity of various nanomaterials, such as carbon nanotubes, graphene oxides, zinc oxides, cerium oxides, quantum dots, and silica NPs.…”