Green Synthesized Nanomaterials as Theranostic Platforms for Cancer Treatment: Principles, Challenges and the Road Ahead.

With the emergence of nanotechnology, new methods have been developed for engineering various nanoparticles for biomedical applications. Nanotheranostics is a burgeoning research field with tremendous prospects for the improvement of diagnosis and treatment of various cancers. However, the development of biocompatible and efficient drug/gene delivery theranostic systems still remains a challenge. Green synthetic approach of nanoparticles with low capital and operating expenses, reduced environmental pollution and better biocompatibility and stability is a latest and novel field, which is advantageous over chemical or physical nanoparticle synthesis methods. In this article, we summarize the recent research progresses related to green synthesized nanoparticles for cancer theranostic applications, and we also conclude with a look at the current challenges and insight into the future directions based on recent developments in these areas.

Ultra-small silver nanoparticles induced ROS activated Toll-pathway against Staphylococcus aureus disease in silkworm model.

The present study investigated the therapeutic action of flavonoids loaded silver nanoparticles (FLV-Ag NPs) on a silkworm, Bombyx mori L., larvae infected by the S. aureus, where an in vivo model system was used. FLV-Ag NPs were synthesized using a Ricinus communis L. leaf extracted flavonoid mixture in various concentrations. The reduction reaction was performed under a simple sunlight exposure condition. In the reduction process, quercetin and kaempferol loadings were also found. They were confirmed by UV-visible, TEM, XRD, XPS, DLS and FTIR spectroscopic techniques. TEM confirmed that the synthesized NPs were monodispersed and with an average size of 5.8nm±0.04. Initially, those synthesized FLV-Ag NPs were tested against S. aureus in in vitro by comparing their potential inhibitory activity with only flavonoids mixture (FLVs) and pure silver nanoparticles (Ag NPs). Furthermore, these FLV-Ag NPs were used to treat S. aureus infected B. mori larvae and the therapeutic efficacy was measured. Our results demonstrate that the FLV-Ag NPs are effective in curing the S. aureus infection through the induced expression of antimicrobial peptide genes, the enhanced oxidative enzyme levels, and the promoted phagocytosis of S. aureus by the haemocytes in silkworm larvae. On the basis of these results, it is proposed that the mechanism of the antimicrobial activity of FLV-Ag NPs involves the NPs-insect fat body cell association and a reactive oxygen species-mediated Toll-pathway.

Biofabrication of Ag nanoparticles using Sterculia foetida L. seed extract and their toxic potential against mosquito vectors and HeLa cancer cells.

A one-step and eco-friendly process for the synthesis of silver-(protein-lipid) nanoparticles (Ag-PL NPs) (core-shell) has been developed using the seed extract from wild Indian Almond tree, Sterculia foetida (L.) (Sterculiaceae). The reaction temperature played a major role in controlling the size and shell formation of NPs. The amount of NPs synthesized and qualitative characterization was done by UV-vis spectroscopy and transmission electron microscopy (TEM), respectively. TEM studies exhibited controlled dispersity of spherical shaped NPs with an average size of 6.9±0.2nm. Selected area electron diffraction (SAED) and X-ray diffraction (XRD) revealed 'fcc' phase and crystallinity of the particles. X-ray photoelectron spectroscopy (XPS) was used to identify the protein-lipid (PL) bilayer that appears as a shell around the Ag core particles. The thermal stability of the Ag-PL NPs was examined using thermogravimetric analysis (TGA). Further analysis was carried out by using Fourier transform infrared spectroscopy (FTIR), where the spectra provided evidence for the presence of proteins and lipid moieties ((2n-octylcycloprop-1-enyl)-octanoic acid (I)), and their role in synthesis and stabilization of Ag NPs. This is the first report of plant seed assisted synthesis of PL conjugated Ag NPs. These formed Ag-PL NPs showed potential mosquito larvicidal activity against Aedes aegypti (L.), Anopheles stephensi Liston and Culex quinquefasciatus Say. These Ag-PL NPs can also act as promising agents in cancer therapy. They exhibited anti-proliferative activity against HeLa cancer cell lines and a promising toxicity was observed in a dose dependent manner. Toxicity studies were further supported by the cellular DNA fragmentation in the Ag-PL NPs treated HeLa cells.