Plasmon Resonance Band Research Articles

On the splitting of the surface plasmon resonance band of gold nanopillars developed on rippled Si surface

In this work, we reported split surface plasmon resonance (SPR) bands originated from the Au nanopillars developed on rippled Si substrates. This is the first report of gold SPR splitting on a pre-structured Si surface. The Si surface was subjected to a bombardment of Ar ions to fabricate ripples on the surface. A 5 nm thin layer of Au was then deposited on the rippled surface, and the SPR was studied using UV–visible spectroscopy. Further, X-ray diffraction (XRD), atomic force microscopy (AFM), X-ray absorption near edge structure (XANES), and extended X-ray absorption fine structure spectroscopy (EXAFS) were used to characterize the prepared samples. The AFM confirmed that the deposited gold is in nanopillar form, and the rippled surface governs the growth, shape, and size of gold nanopillars. A large aspect ratio has been observed for the nanopillars, resulting in a red-shifted and split SPR band. The experimental XANES of Au L3-edge were successfully mimicked by simulated XANES, confirming the existence and signature of the nanostructure. For the first time, the local structure information of Au nanopillars constructed on rippled Si substrate has been obtained using the EXAFS approach in different directions and correlated with the plasmonic bands.

Fabrication of 3D popcorn-like Ag microstructures film array substrate: SERS and catalytic property

Surface-enhanced Raman scattering (SERS) has tremendous significance in the fields of ultrasensitive detection and real-time in situ monitoring in catalysis. However, it remains a challenge to simultaneously achieve higher-quality SERS and excellent plasmonic catalytic properties in a nano/microstructure substrate under random excitation light. Here, we propose the design of a three-dimensional (3D) popcorn-like silver (Ag) microstructure (MS) with diameter of 1.2 ± 0.1 µm and a unique rough surface topography, realize a wide surface plasmon resonance (SPR) band ranging from 300 nm to 1100 nm, approximating a full spectrum. The popcorn-like Ag MSs with full-spectrum property effectively broaden the spectral overlap between the SPR band and wavelength of excitation light or absorption of probe molecules. Moreover, the 3D popcorn-like Ag MSs were used to construct a monolayer film array substrate on silicon wafer with a good homogeneity over large areas by an interfacial self-assembly method. The monolayer Ag MSs film array substrate can provide abundant “hot spots” and present excellent SERS performance for sensitive detection of Rhodamine 6G (Rh6G) with a low detection limit of 10−9 M. The single-layer Ag MSs film array with superior SERS activity is utilized for in situ monitoring the plasmonic catalytic kinetics of 4-nitrothiophenol (4-NTP) dimerized into 4, 4′-dimercaptoazobenzene (DMAB) under 532 nm and 785 nm excitation, respectively. The mechanism on plasmonic catalytic reaction of the popcorn-like Ag MSs substrate is systemically investigated by experimental and theoretical simulations aspects. The Ag MSs film array substrate will offer a new strategy to further explore applications of SERS in sensors, photocatalysis, and bio/chemical analysis.

Evaluation of antimicrobial, anti-inflammatory and cytotoxic effects of silver nanoparticles synthesised from Cynodon dactylon

Plant mediated synthesis of metal nanoparticles (MNPs) has been considered as a reliable green technique for mitigating the involvement of toxic chemicals and which is widely used for desired applications. In the present study, a simple and environment friendly approach for the synthesis of silver nanoparticles (AgNPs) using the aqueous extract of Cynodon dactylon was proposed. The phytochemicals present in C. dactylon acted as the reducing as well as the capping agents during the nanoparticle synthesis. The aqueous extract of C. dactylon added to AgNO3 solution showed a colour change from brown to black at room temperature which confirmed the formation of AgNPs. UV-Vis spectral analysis revealed the surface plasmon resonance band of synthesised AgNPs at around 380 nm, while FT-IR spectroscopy confirmed the role of biomolecules present in the plant extract in the reduction and efficient stabilisation of AgNPs. The X-ray diffraction (XRD) patterns confirmed distinctive peaks corresponding to the crystalline planes of cubic silver. Shape and surface morphology of green AgNPs were examined by SEM. Biosynthesized AgNPs were predominantly cubical and spherical with an average particle size of 30.5 nm approximately as observed through SEM and DLS analysis respectively. The EDS analysis displayed intense signals of silver element. The stability of AgNPs was confirmed by zeta potential analysis. A negative zeta potential value of −17.1 mV indicated the stability and good dispersion of AgNPs. Antimicrobial and anti-inflammatory potentials of green synthesised AgNPs were analysed through in vitro techniques. The cytotoxic effect of green AgNPs on normal fibroblast cells (L929) was studied to analyse its effect on normal cells.

Fluorescence quenching of fluorescein dye using silver nanoparticles

Fluorescence quenching is indeed a versatile and widely used technique in various scientific disciplines, including chemistry, biology, and medicine. It provides valuable information about the behaviour of small molecules in organized systems and offers insights into the properties of the microenvironments surrounding the fluorescent probe and quencher molecules. In the present work, we report the synthesis of citrate-stabilized silver nanoparticles and also investigate the effect of the prepared silver nanoparticles on the fluorescence luminous intensity of fluorescein dye with different concentrations of silver nanoparticles. The UV–visible spectrometer is used to study the absorption properties of silver nanoparticles. We have obtained a single surface plasmon resonance band, which indicates the isotropic nature of particles. The particle size was obtained from the absorption spectra, using the Mie scattering theory. The luminous intensity of fluorescein dye was found to be quenched in addition to silver nanoparticles. The morphological analysis is done using SEM.

The Characterization and Study of Antibacterial, Free Radical Scavenging, and Anticancer Potential of Livistona chinensis-Mediated Silver Nanoparticles

In the present research, Livistona chinensis leaf extracts were utilized as reductants to bio-fabricate silver nanoparticles (LC-AgNPs) and this was followed by the evaluation of their antioxidant, antibacterial, and anticancer potential. Multiple parameters were optimized for the formation and fidelity of LC-AgNPs. The color shift of the reaction mixture from yellow to dark brown confirmed the LC-AgNPs formation. UV/VIS spectroscopy exhibited a surface plasmon resonance (SPR) band at 436 nm. The Fourier transform infrared (FTIR) spectroscopy spectrum depicted phytochemicals in the plant extract acting as bio-reducers for LC-AgNPs synthesis. The XRD pattern confirmed the presence of LC-AgNPs by showing peaks corresponding to 2θ angle at 8.24° (111), 38.16° (200), 44.20° (220), and 64.72° (311). Zetasizer analysis exhibited size distribution by intensity of LC-AgNPs with a mean value of 255.7 d. nm. Moreover, the zeta potential indicated that the AgNPs synthesized were stable. The irregular shape of LC-AgNPs with a mean average of 38.46 ± 0.26 nm was found by scanning electron microscopy. Furthermore, the antioxidant potential of LC-AgNPs was examined using a DPPH assay and was calculated to be higher in LC-AgNPs than in leaf extracts. The calculated IC50 values of the LC-AgNPs and plant extract are 85.01 ± 0.17 and 209.44 ± 0.24, respectively. The antibacterial activity of LC-AgNPs was investigated against Escherichia coli, Pseudomonas aeruginosa, and Bacillus subtilis as well as Staphylococcus aureus, and maximum potential was observed after 24 h against P. aeruginosa. Moreover, LC-AgNPs exhibited maximum anticancer potential against TPC1 cell lines compared to the plant extract. The findings suggested that LC-AgNPs could be used as antioxidant, antibacterial, and anticancer agents for the cure of free-radical-oriented bacterial and oncogenic diseases.

Fenugreek seeds extract mediated nickel oxide nanoparticles and their potential biomedical applications

The biogenic nanoparticle synthesis is much interest in the field of modern science and technology because of their excellent inhibition of potential pathogens. A quick, dependable, and efficient way to create very stable metal nanoparticles is by Phytosynthesis. Hence, Fenugreek seeds extract-mediated nickel oxide nanoparticles (NF) are synthesized by an eco-friendly, greener approach. Numerous characterization methods, including X-ray diffraction (XRD), Fourier transform infrared (FT-IR), ultraviolet visible (UV–Vis), photoluminescence (PL), scanning electron microscope (SEM), transmission electron microscope (TEM), and energy-dispersive X-ray spectroscopy (EDX), were used to confirm the as-prepared nanoparticles. Powder X-ray diffraction (PXRD) and selected area electron diffraction (SAED) show the prepared NiO NPs crystallinity. The FT-IR spectrum ensures the vibrational modes present in the prepared compound. The formation of NiO NPs is confirmed from the ultraviolet–visible (UV–Vis) spectrum analysis with the surface plasmon resonance (SPR) band at 320 nm. The morphological behavior is shown by the field emission-scanning electron microscope (FE-SEM) and high-resolution transmission electron microscope (HR-TEM). This prepared Fenugreek seeds extract assisted NiO NPs were examined with different biomedical studies such as anti-diabetic, anti-oxidant, and anti-inflammatory. The green approach to NiO NPs shows 82.21 % anti-diabetic, 79.82 % anti-oxidant, and 94.54 % anti-inflammatory and anti-bacterial activities. Moreover, it can act as an excellent inhibitor with the potential to cure various diseases like diabetes, oxidative stress, and inflammation.

Synthesized green silver nano particles of Herpetospermum darjeelingense shows enhanced In vitro Antimicrobial, Antioxidant and Hepatoprotective activity

Silver nanoparticles (AgNP’s) are 1 - 100nm sized constituents providing additional surface area in formation of plentiful coordinate bonds with various ligands. Green mode of AgNP’s synthesis has aided in development of advanced formulations towards treating complex human ailments. Herpetospermum darjeelingense (C.B.Clarke) H. Schaef. and S.S. Renner is an under investigated endemic ethnomedicinally significant cucurbit climber with no work based on synthesis and exploration of biogenic AgNP’s being conducted previously employing its solvent extracts. This paper aims to provide insights on the green synthesized AgNP’s besides studying its antimicrobial, antioxidant and hepatoprotective efficacy. Methanolic extracts of H. darjeelingense were utilized to synthesize AgNP’s via reduction of silver nitrate following UV-Visible spectroscopic and scanning electron microscopic characterization depicting surface plasmon resonance bands at around 430nm wavelength with spherical to cubical shaped AgNP’s ranging between 40–80nm. The methanol based sample extracts did not portray any inhibition zone in antimicrobial assay with the AgNP’s showing considerable zone of inhibition against Escherichia coli, Klebsiella pneumoniae and Staphylococcus aureus indicating anti-microbial effectiveness of silver nano formulations. The highest free radical scavenging potential was shown by 50mg/ml (91.99%) silver nano formulation with minimal being recorded in 12.5mg/ml (50.11%) nanoparticle concentrate including a noted gradual increase in anti-lipid peroxidation ability from 12.5mg/ml (7.157±0.08273mg/ml Tocopherol equivalent) to 50mg/ml (18.128±0.03152mg/ml Tocopherol equivalent) nanoparticle formulation clearly portraying statistically significant elevated results in comparison to plain sample extracts depicting its anticipated usage in pharmaceutical applications concerning antibacterial, antioxidative and hepatoprotective features.

In situ tuning and investigating the growth process of size controllable gold nanoparticles and statistical size prediction analysis

A critical understanding of the formation and growth process of gold nanoparticles (GNPs) is crucial, in order to synthesize monodisperse gold nanocrystals of controllable size and shape in a predictable way. GNPs of different shapes and sizes can be produced by altering different physicochemical reaction conditions, such as pH, temperature, and the ratio of reactants. The significant variations in the morphological features of GNPs can be monitored in situ in a time-dependent manner by using UV–visible spectroscopy. In this study, we have synthesized seedless GNPs by reduction of HAuCl4 by using various molar ratios of HEPES and Na2HPO4. The shape and the geometry of the gold nanostructures were optimized by varying the pH (5, 7, and 9) of the HEPES, molar concentrations of disodium phosphate to HAuCl4, and reaction temperatures (20 °C, 40 °C, and 60 °C). The changes in the color of the reaction mixtures over time were recorded in situ in terms of the absorbance of the UV–visible light to tune and investigate the growth process of gold nanostructures. Transmission electron microscopic (TEM) images indicated that the gold nanostructures are anisotropic, stable, and exist in the size range of < 1–100 nm. The present study also confirms that the change in the color of nanostructure reaction mixtures is a function of the surface plasmon resonance bands under the influence of physicochemical reaction conditions and corroborates with the size and shape of nano-gold. Physicochemical parameters such as temperature, pH, and the molar concentration of the reactants act synergistically to influence the growth, molecular mechanics, and reaction thermodynamics that aid to affect the particle size, shape, and surface corona of the GNPs. By tracking the growth process, we can confirm that the nucleation, growth process, size, and shape of the gold nanostructures depend on the HEPES free radicals and phosphate ions which cluster to form polymeric chains on the gold nanocore. The present study's findings explain the growth process of the GNPs of various colors that can be observed by the naked eye and have promising applications, for example in the development of the biosensing rapid lateral flow immunoassays (LFIA) for the detection of mycotoxins in food samples.

Enhanced antidiabetic and antioxidant properties of gold nanoparticles green synthesized using blossom extract of Azadirachta indica: In vitro studies

This study describes the in situ biosynthesis of gold nanoparticles (AuNPs) using neem blossom (Azadirachta indica) extract with enhanced in vitro anti-diabetic and antioxidant properties. The formation of AuNPs was confirmed by the characteristic optical response through the surface plasmon resonance (SPR) band observed around 530 nm. The effect of phytochemical in the formation of AuNPs was investigated using Fourier-transform infrared spectroscopy (FTIR). The effect of reaction parameters such as temperature, pH and precursor concentration on the size and surface morphology of AuNPs was optimized using the SPR band. The metallic form of phytosynthesised AuNPs was confirmed by X-ray photoelectron spectra (XPS) results with a distinctive binding energy difference of 4f shells ΔE = 3.8 eV. Transmission electron microscopy (TEM) and X-ray diffraction (XRD) studies confirmed the crystalline nature of the particles formed. The antioxidant property of AuNPs demonstrated the influence of phytochemical surfactants coated on the surface of AuNPs and the results revealed the higher antioxidant (90 %) efficiency compared to standard ascorbic acid. phytosynthesised AuNPs demonstrated 79 % enzyme inhibition efficiency in α-amylase assays. The antimicrobial evaluation results revealed the exceptional microbicidal efficacy of AuNPs against both gram-positive and gram-negative bacteria. Phytochemically activated AuNPs showed improved antioxidant, antimicrobial and antidiabetic properties and it could be a promising candidate for biological applications in medicine.

Faraday rotation enhancement for colloidal spherical Au and Ag nanoparticles and their mixtures

So far, magnetooptical (MO) properties of silver nanoparticles (AgNPs) have been studied only by magnetic circular dichroism (MCD) spectroscopy at the surface plasmon resonance (SPR) band. However, direct knowledge of the Faraday rotation effect (FR) is very important in fundamental research and applications. In the present work, we study an enhancement of FR of individual gold nanoparticles (AuNPs) and AgNPs and their mixture of colloidal aqueous suspension. The Au and Ag spherical NPs were synthesized independently as colloids in an aqueous suspension and then such mixtures were studied (AgNPs were also studied as a suspension in hexane). The noble metal NPs were characterized by TEM, UV–Vis, and refraction methods. The enhancement of FR of individual NPs was observed and it is consistent with available MCD results. For the mixtures, observed changes of magnitude of FR is small, and coupling of both SPR is rather weak. The obtained FR spectra associated with SPR band have been successfully converted to MCD spectra using the Kramers-Kronig transformation. Calculated MCD spectra are consisted with that obtained by direct measurements.

Green Synthesis, Characterization, and Evaluation of Biocompatible Structures of Gold Nanoparticles in Biomedical Applications (Antibacterial, Antifungal, and Anticancer)

Gold nanoparticles (AuNPs) stand out due to their low toxicity and high compatibility, and the large and modifiable surface areas they provide. In this study, the leaves of Celtis tournefortii Lam. (CT) were used for the green synthesis of gold nanoparticles (AuNPs) first time. The size, shape, surface charge, and functionality of the synthesized AuNPs are described in detail. The suggested mechanisms of action on the tested target cells are highlighted. The biological activities (antibacterial, antifungal, and anticancer) of “green” AuNPs and their further biomedical application possibilities are also discussed. Synthesized AuNPs displayed a spherical appearance, surface plasmon resonance band at 553.67 nm wavelength, and surface charge of -16.53 mV. Particle morphology, size, and surface charge were observed to be affected by the leaf extract used in the reduction reaction. FTIR and TGA-DTA data revealed that functional groups from the CT extract participate in the synthesis and stabilization of AuNPs. AuNPs showed antibacterial and antifungal effects on all the strains and yeast tested by microdilution method (MIC). AuNPs showed dose-dependent cytotoxic activity on cancerous cell lines (SKOV-3, CaCo2, and U118). The obtained results highlight a potentially low-cost green synthesis method using CT leaf extract to synthesize AuNPs showing important biological properties.

Green synthesis of silver nanoparticles using Adhatoda vasica leaf extract and its application in photocatalytic degradation of dyes

The paper describes biogenic synthesis of silver nanoparticles (AgNPs) using Adhatoda vasica leaf extracts at room temperature. The prepared AgNPs were characterized by UV–visible spectroscopy, Fourier-transform infrared spectroscopy, powder X-ray diffraction, Energy dispersive X-ray (EDX), High Resolution Transmission Electron Microscope, Scanning Electron Microscopy and Thermogravimetric analyser. The bio reduction method is devoid of any toxic chemicals, organic solvents, and external reducing, capping and stabilizing agent. The synthesized AgNPs had spherical shape with particle size ranging between 3.88 and 23.97 nm and had face centered cubic structure. UV–visible spectral analysis confirmed the formation of AgNPs with a characteristic surface plasmon resonance band at 419 nm. The EDX pattern revealed the presence of elemental Ag in AgNPs. The prepared AgNPs were used for degradation of Amaranth, Allura red and Fast green in aqueous medium, with ≥ 92.6% efficiency within 15 min using 5 mg of AgNPs. The optical bandgap, Eg value of 2.26 eV for AgNPs was found to be effective for rapid photocatalytic degradation of all the three dyes. The degradation process was observed to follow pseudo first order kinetics.

Label-free SERS for rapid identification of interleukin 6 based on intrinsic SERS fingerprint of antibody‑gold nanoparticles conjugate

A label-free surface-enhanced Raman scattering (SERS) was designed for sensitive detection of interleukin-6 (IL-6). The sensing element composed of anti-IL-6 antibodies adsorbed on the surface of spherical gold nanoparticles (AuNPs) as SERS-active surface. The principle of detection was probing antibody conformational changes using its intrinsic SERS fingerprint after binding to IL-6. Comparison of SERS spectra of antibody before and after binding to IL-6 showed that secondary structure of antibody does not change upon binding to IL-6. Vibrational information from disulfide bonds ν(SS) in antibody structure indicated some changes of geometry around SS bridges as a consequence of the immunocomplex formation. Transmission electron microscopy (TEM) and UV–Vis spectroscopy were used to confirm AuNPs conjugation with antibody as well as IL-6 binding to antibody on the surface of AuNPs. The SERS-based immunoassay showed a wide linear range (2.0–1000 pg mL−1) and a high sensitivity with a limit of detection (LOD) as low as 0.91 pg mL−1 (0.04 pM) without using any extrinsic Raman label. UV–Vis spectroscopy was employed as a conventional method for IL-6 detection based on observation of any change in the position of localized surface plasmon resonance (LSPR) band of AuNPs-antibody conjugates with LOD of 10 ng mL−1.

Synthesis of small-sized gold nanorod using catechol as a reducing agent

Facile preparation of small gold nanorod with controllable and large surface plasmon resonance band is of great value for applications in especially the biomedical and sensing fields. In this work, we propose that without addition of additive to complicate the experimental system catechol of a very weak reducibility can be used as reducing agent for seed-mediated synthesis of gold nanorod. Under a temperature of 40 °C and a catechol concentration of 17.5 mM, monodisperse gold nanorod with a high shape yield, a largest plasmon wavelength of 918 nm, and especially a small diameter of 9.8 nm can be acquired simultaneously. A good tune over the plasmon wavelength is also shown by varying the amount of silver ion. Besides, the effects of experimental parameters including silver ion, cetyltrimethylammonium bromide, gold seed and catechol have also been carefully studied, and the morphological and structural evolutions of the particle have been discussed based on reported growth mechanism.

Enhancing the prodigiosin pigment by adding Ag\\TiO2 synergism for antibacterial activity

To treat diseases brought on by drug-resistant microbes, researchers are presently using nanotechnology as one of the tools for studying the most obscure corners of medical sciences. The biological synthesis regarding Ag/TiO2 synergism in prodigiosin pigment was the primary focus of the presented work. Inhibitory and bactericidal properties of silver nanoparticles (AgNPs) have long been recognized. Titanium dioxide nanoparticles (TiO2 NPs) are employed as antibacterial agents in a variety of therapeutic sources. With using Nd:Yag laser (1064 nm), the composition has been synthesized by using environmentally friendly laser ablation in a liquid method. UV–visible spectroscopy, X-ray diffraction (XRD), and scanning electron microscopy (SEM) have been utilized for the analysis of the synthesized NPs. Optimal biosynthesis results showed a rise in the intensity of Surface Plasmon Resonance (SPR) bands of the NPs with shifting at 300 nm. TiO2 absorption peak at 230 nm. The results showed that the UV visible absorbance regarding prodigiosin pigment was at OD529. AgNPs/TiO2 exerted maximum antibacterial activity towards (Streptococcus, Bacillus subtilis, E. coli, Proteus vulgaris) Gram-negative and Gram-positive bacteria. The various Gram-negative and Gram-positive bacteria were subjected to various treatments (prodigiosin with Ag, prodigiosin pigment, and prodigiosin synergism with Ag/TiO2). The synergism is the best for antimicrobials than each one alone.

Silk fibroin-based green colloidal silver nanoparticle synthesis and their antibacterial and anticancer properties

Aqueous silk fibroin (SF), derived from Bombyx mori silk, was used to synthesize colloidal silver nanoparticles (AgNPs) in situ under white light and at ambient temperature. A characteristic surface plasmon resonance (SPR) band at 425–435 nm from the UV–Vis spectrum provided evidence of the formation of AgNPs by UV–Visible spectroscopy. The nanoparticles that were synthesized were spherical with smooth surfaces, as evidenced by the transmission electron microscope (TEM) photographs. The size of the particles was between 35 and 40 nm. Additionally, X-ray diffraction (XRD) investigation supports the existence of silver's nanocrystalline phase with FCC crystal structure. The human bacterial pathogens Escherichia coli (E. coli) and Bacillus subtilis (B. subtilis) were significantly inhibited by the biogenic silver nanoparticles' antibacterial activity. The synthesized nanoparticles also show an excellent anti-cancer activity in lowest dosage.

Exploring the photophysical interaction of xanthene dyes with gold nanorods by optical spectroscopic techniques and in-vitro cytotoxicity studies of dye-nano conjugates

The current study investigates the photophysical interactions of xanthene dyes such as fluorescein (FL) and rose bengal (RB) dyes with cetyltrimethylammonium bromide stabilized gold nanorods (CTAB-AuNRs) using optical spectral techniques, and computational interaction analyses. When xanthene dyes are conjugated with CTAB-AuNRs, significant modifications in their optical spectroscopic characteristics are found. In the absorption spectrum analyses of dye-AuNRs systems, the appearance of longitudinal plasmon resonance bands and the hypochromic behavior of xanthene dyes were observed in response to the interaction of CTAB-AuNRs. The gathered extinction spectral results indicated that there were significant electrostatic interactions between the positively charged CTAB-AuNRs and the negatively charged xanthene dye molecules. At the same time, the substantial quenching with a reduced quantum yield of the dye molecules is shown in the emission spectra of xanthene dyes with CTAB-AuNRs. The strong electrostatic interactions and ground state complex between xanthene dyes and CTAB-AuNRs have been suggested as the mechanism of emission quenching. The results of the emission quenching are supported by the calculated high binding constant values. Additionally, the results of computational interaction investigations also demonstrate the near closeness of xanthene dye molecules and CTAB-AuNRs. Finally, the cytotoxicity of free dyes and dye-nanoconjugates was next tested against breast (MCF-7) and lung (A-549) cancer cells. All the tested samples exhibit significant antiproliferative activity against MCF-7 and A-549 cancer cells. These cytotoxic study results showed that cells treated with xanthene dyes were less sensitive than FL-AuNRs and RB-AuNRs dye nanoconjugates.

Small size silver nanoparticles loaded with glycoside rich portion of Boerhavia Diffusa Linn. promotes wound healing: in-silico and in-vivo studies.

Silver nanoparticles (Ag-NPs) are increasingly used in various fields, including medicine, owing to their unique physicochemical properties. Due to their smaller size, the contact with biological components is increased, and consequently, it performs better as an antibacterial and antimicrobial. In this study, the authors have focused on the synthesis of small-sized spherical silver nanoparticles (Ag-NPs) by a chemical reduction method using two different capping agents and concentrations of AgNO3 as a precursor. Additionally, various amounts of Glycoside Rich Portion (GRP) isolated from the roots of Boerhaavia diffusa L. were loaded onto synthesised Ag-NPs. Punarnavoside, a glycoside found in GRP, has been reported to have antifibrinolytic properties. The docking study of punarnavoside present in GRP has shown good binding affinity with various antifibrinolytic targets. The surface plasmon resonance band, particle size, polydispersity index, and zeta potential values have been used to analyse the interaction and kind of bonding between GRP and Ag-NPs. A batch of trisodium citrate (TSC)-capped Ag-NPs loaded with 0.1ml of 1% GRP solution showed particle size smaller than 50nm with a stable zeta potential value of -55.3mV. Fourier transform infrared spectroscopic results showed CO and C-O bonds in GRP interacted with Ag-NPs. A batch of TSC-capped GRP-loaded Ag-NPs (1%)-based gel was developed using carbopol as a polymer. The TSC-capped GRP-loaded silver nanogel had greater wound closure in rats, as observed during the histopathological studies in the excision wound model. The antifibrinolytic activity of GRP, when coupled with the antibacterial and bactericidal properties of silver, demonstrated an increased wound healing effect.

One-minute ultrasound-assisted synthesis of nanostructured silver particles extracted from Desmodium gangeticum for enhanced photocatalytic degradation of toxic dyes and antibacterial studies

In the present work, we are reporting a one-minute synthesis of silver nanoparticles using Desmodium gangeticum seed extract by ultrasonication method and their photocatalytic degradation of toxic dyes. The surface plasmon resonance (SPR) band of DG-AgNPs was observedat 411 nm. The calculated average particle size was 14.23 nm by HR-TEM. Toxic dyes such as Indigo Carmine, Crystal Violet, Aniline Blue, and Brilliant Blue have been degraded using DG-AgNPs as photocatalysts. Furthermore, DG-AgNPs,antibacterial activity was examined against the gram-positive and negative pathogens Staphylococcus aureus and Escherichia coli, the DG-AgNPs have shown excellent antibacterial efficacy.

Gold Nanoparticles as Monoanion Sensors through Modified Electrophilicity

Derived from malachite green, new triaryl-carbonium-ion-functionalized gold nanoparticles have been synthesized for detecting anions. The detection process, and concomitant colour change, is based on charge compensation on the surface of nanoparticles, which triggers their aggregation, resulting in a bathochromic shift of the plasmon resonance band. The difference in electrophilicity of the malachite green triaryl ions in solution or on gold nanoparticles makes it possible to distinguish different anions related to their nucleophilic character.