Biogenic synthesis of silver nanoparticles using rhizome extract of Dysosma pleiantha and its antiproliferative effect against breast and human gastric cancer cells.

Synthesis of biogenic metal nanoparticles using plant extract has gained considerable attention in recent years. The present study aims to synthesize and investigate the cytotoxic effect of silver nanoparticles (AgNPs) from Dysosma pleiantha rhizome extract. The green biosynthesis of AgNPs was verified by ultraviolet visible spectrometer, and characterized using fourier transform infrared spectroscopy, transmission electron microscopy and scanning electron microscopy. Results of microscopic studies revealed that the synthesized AgNPs were a spherical shape with an average size of 76 nm. We also examined the anti-cancer activity of biologically synthesized AgNPs. The dose-dependent cytotoxicity was observed in the breast cancer cell lines MDA-MB-231 and MDA-MB-453 treated with biogenically synthesized AgNPs, and the IC50 was recorded at 33.521  and 36.25 µM respectively. The DNA fragmentation analysis showed that the MDA-MB-231 cells treated with increasing concentrations of AgNPs significantly triggered the fragmentation of DNA. In addition, the synthesized AgNPs exhibited dose dependent cytotoxic potential against human gastric cancer cell lines and the IC50 was recorded at 7.14 µM. Thus, the green biosynthesized AgNPs from D. pleiantha rhizome can be used in the novel development of anticancer drugs.

Author Correction: One-step Solution Processing of Ag, Au and Pd@MXene Hybrids for SERS.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Simultaneous Production and Surface Functionalization of Silver Nanoparticles for Label-free Colorimetric Detection of Copper Ion.

In this work, a simple method was developed to simultaneously fabricate silver nanoparticles (AgNPs) and modify their surfaces with recognition functional groups for colorimetric detection of Cu2+ ions. To prepare the AgNPs with proper functional group on their surface for detection of Cu2+ ions, photochemical reaction was employed and a photoactive species of tyrosine (Tyr) was used to trigger the photoreduction of AgNPs, while the oxidized Tyr (TyrOx) was used to functionalize the AgNPs surface at the same time. To understand the behaviors, the prepared color AgNPs colloidal solution was characterized by UV-visible spectrometer, FT-IR spectrometer, dynamic light scattering (DLS), X-ray photoelectron spectrometer (XPS) and density functional theory (DFT). Based on DFT calculation results, TyrOx was adsorbed on the surface of AgNPs by the quinone ring and its functional group of amino acid was freely exposed to the aqueous media for rapid interaction of Cu2+ ions. Based on detection of different metal ions, TyrOx@AgNPs were selective to interact with Cu2+ ions through formation of highly stable Cu2+-TyrOx@AgNPs complexes. The evidence in formation of Cu2+-TyrOx@AgNPs complex could be obtained through the red shift of the surface plasmonic resonance (SPR) band of TyrOx@AgNPs located at 557 nm, which gives a color change from light yellow to brown color allowing visual identification of Cu2+ ions for rapid screening purposes. For quantitative analysis, a band intensity ratio of A557/(A404-A557) was constructed to correlate with the concentration of Cu2+ ions. A linear range up to 10 µM with a detection limit close to 150 nM was found.

Biocompatible 3D SERS substrate for trace detection of amino acids and melamine.

A novel, low-cost and biocompatible three-dimensional (3D) substrate for surface-enhanced Raman spectroscopy (SERS) is fabricated using gold nanoparticles (AuNPs) loaded on cellulose paper for detection of amino acids and melamine. Dysosma pleiantha rhizome (Dp-Rhi) capped AuNPs (Dp-Rhi_AuNPs) were prepared by in situ using aqueous extract of Dp-Rhi and in situ functionalized Dp-Rhi on AuNPs surface was verified by Fourier transform infrared spectroscopy and zeta potentials analysis shows a negative (-18.4mV) surface charges, which confirm that presence of Dp-Rhi on AuNPs. The biocompatibility of Dp-Rhi_AuNPs is also examined by cell viability of FaDu cells using MTS assay and compared to control group. In conclusion, the SERS performance of AuNPs@cellulose paper substrates were systematically demonstrated and examined with different excitation wavelengths (i.e. 532, 632.8 and 785nm lasers) and the as-prepared 3D substrates provided an enhancement factor approaching 7 orders of magnitude compared with conventional Raman intensity using para-nitrothiophenol (p-NTP), para-aminothiophenol (p-ATP) and para-mercaptobenzoic acid (p-MBA) as probe molecules. The strong electromagnetic effect was generated at the interface of AuNPs and pre-treated roughened cellulose paper is also investigated by simulation in which the formation of possible Raman hot-spot zone in fiber-like microstructure of cellulose paper decorated with AuNPs. Notably, with optimized condition of as-prepared 3D AuNPs@cellulose paper is highly sensitive in the SERS detection of aqueous tyrosine (10-10M) and melamine (10-9M).

One-step Solution Processing of Ag, Au and Pd@MXene Hybrids for SERS.

We report on one-step hybridization of silver, gold and palladium nanoparticles from solution onto exfoliated two-dimensional (2D) Ti3C2 titanium carbide (MXene) nanosheets. The produced hybrid materials can be used as substrates for surface-enhanced Raman spectroscopy (SERS). An approximate analytical approach is also developed for the calculation of the surface plasmon resonance (SPR) frequency of nanoparticles immersed in a medium, near the interface of two dielectric media with different dielectric constants. We obtained a good match with the experimental data for SPR wavelengths, 440 nm and 558 nm, respectively for silver and gold nanoparticles. In the case of palladium, our calculated SPR wavelength for the planar geometry was 160 nm, demonstrating that non-spherical palladium nanoparticles coupled with 2D MXene yield a broad, significanlty red-shifted SPR band with a peak at 230 nm. We propose a possible mechanism of the plasmonic hybridization of nanoparticles with MXene. The as-prepared noble metal nanoparticles on MXene show a highly sensitive SERS detection of methylene blue (MB) with calculated enhancement factors on the order of 10(5). These findings open a pathway for extending visible-range SERS applications of novel 2D hybrid materials in sensors, catalysis, and biomedical applications.

Analyte-induced photoreduction method for visual and colorimetric detection of tyrosine.

A new method based on photochemical formation of silver nanoparticles (AgNPs) was developed for detection of tyrosine (Tyr). To selectively detect Tyr and to simplify the detection procedure, the photoactivity of Tyr was utilized to trigger the photochemical reduction in production of AgNPs. The drastic change of solution color caused by the surface plasmon resonance (SPR) absorption band of the formed AgNPs was used to extract the quantitative information of Tyr. This developed method is simple in detection, while both the sensitivity and selectivity are significant improved. Meanwhile, the solution color was changed from colorless to dark yellow after the formation of AgNPs, which allows a much higher sensitivity in visual identification when compared with the SPR band shifting technique commonly, used in conventional colorimetric methods. To optimize the detection system and to understand the mechanism in this proposed method, parameters such as irradiation time, intensity of light source, and the concentration of Tyr were systematically examined. Results indicated that these factors mainly affected the reaction rate of photoreduction. The morphologies of the formed AgNPs were similar, but with small differences in particle sizes. In the examination of selectivity, sixteen other amino acids were examined. Results indicated that only amino acids of tryptophan, cysteine and histidine are photoactive and possess potential interferences in analysis of Tyr. Quantitative studies indicated that a linear response up to 10 µM with a detection limit of 100 nM could be obtained. For visually detection, color change could be observed with a concentration as low as 500 nM of Tyr.

Anti-metastatic activity of biologically synthesized gold nanoparticles on human fibrosarcoma cell line HT-1080.

Plants are exploited as a potential source for the large-scale production of noble gold nanoparticles in the recent years owing to their various potential applications in nanobiotechnology and nanomedicine. The present work describes green biosynthetic procedures for the production of gold nanoparticles for the first time by using an aqueous extract of the Dysosma pleiantha rhizome. The biosynthesized gold nanoparticles were confirmed and characterized by ultraviolet-visible spectroscopy, Fourier transform infrared spectroscopy, transmission electron microscopy, and scanning electron microscopy equipped with energy dispersive spectroscopy. The results revealed that aqueous extract of D. pleiantha rhizome has potential to reduce chloroauric ions into gold nanoparticles and the synthesized gold nanoparticles were showed spherical in shape with an average of 127nm. Further, we investigated the anti-metastatic activity of biosynthesized gold nanoparticles against human fibrosarcoma cancer cell line HT-1080. The results showed that the biosynthesized gold nanoparticles were non-toxic to cell proliferation and, also it can inhibit the chemo-attractant cell migration of human fibrosarcoma cancer cell line HT-1080 by interfering the actin polymerization pathway. Thus, the usage of gold nanoparticles biosynthesized from D. pleiantha rhizome can be used as a potential candidate in the drug and gene delivery to metastatic cancer.