Reduction Of Silver Nitrate Research Articles

Facile and Eco-Friendly Synthesis of Silver Nanoparticles using Semecarpus anacardium and their Antibacterial and Anticancer Activity

Plant extracts are utilized to synthesize nanoparticles containing bioactive compounds that can effectively decrease metal toxicity. In present study, the aqueous extracts of Semecarpus anacardium leaves and stems were used to reduce silver nitrate and synthesize silver nanoparticles (AgNPs), which have potent antibacterial and anticancer effects. The physico-chemical methods such as XRD, UV-Vis, Fourier transform IR and SEM were used to characterize the biogenci silver nanoparticles. These methods validated the synthesis of AgNPs with smaller size and homogeneously sphere-shaped AgNPs (10-50 nm) after incubation with S. anacardium leaf and stem extract. Stem extract derived AgNPs showed the significant cancer fighting abilities in the human breast (MDA-MB-231) and prostate adenocarcinoma (PC-3) cells compared to that of derived AgNPs. Stem extract derived AgNPs exhibits the significant antibacterial activity against E. coli and B. subtilis with respect to the gentamycin. Additionally, the study demonstrated that green synthetic AgNPs may be investigated for use as a treatment against bacterial infections.

Caralluma pauciflora based Ag-NPs activate ROS - induced apoptosis through down-regulation of AKT, mTOR and pI3K signaling in human gastric cancer (AGS) cells

The phytochemicals found in Caralluma pauciflora were studied for their ability to reduce silver nitrate in order to synthesise silver nanoparticles (AgNPs) and characterise their size and crystal structure. Thunbergol, 1,1,6-trimethyl-3-methylene-2-(3,6,9,13-tetram, Methyl nonadecanoate, Methyl cis-13,16-Docosadienate, and (1R,4aR,5S)-5-[(E)-5-Hydroxy-3-methylpent were the major compounds identified in the methanol extract by gas chromatography–mass spectrum analysis. UV/Vis spectra, Fourier-transform infrared spectroscopy, x-ray diffraction, scanning electron microscope with Energy Dispersive X‐ray Analysis (EDAX), Dynamic Light Scattering (DLS) particle size analyser and atomic force microscope (AfM) were used to characterise the Caralluma pauciflora plant extract-based AgNPs. The crystal structure and estimated size of the AgNPs ranged from 20.2 to 43 nm, according to the characterization data. The anti-cancer activity of silver nanoparticles (AgNPs) synthesised from Caralluma pauciflora extract. The AgNPs inhibited more than 60% of the AGS cell lines and had an IC50 value of 10.9640.318 g, according to the findings. The cells were further examined using fluorescence microscopy, which revealed that the AgNPs triggered apoptosis in the cells. Furthermore, the researchers looked at the levels of reactive oxygen species (ROS) in cells treated with AgNPs and discovered that the existence of ROS was indicated by green fluorescence. Finally, apoptotic gene mRNA expression analysis revealed that three target proteins (AKT, mTOR, and pI3K) were downregulated following AgNP therapy. Overall, the findings imply that AgNPs synthesised from Caralluma pauciflora extract could be used to treat human gastric cancer.

Phytofabricated bimetallic synthesis of silver-copper nanoparticles using Aerva lanata extract to evaluate their potential cytotoxic and antimicrobial activities

In this study, we demonstrate the green synthesis of bimetallic silver-copper nanoparticles (Ag–Cu NPs) using Aerva lanata plant extract. These NPs possess diverse biological properties, including in vitro antioxidant, antibiofilm, and cytotoxic activities. The synthesis involves the reduction of silver nitrate and copper oxide salts mediated by the plant extract, resulting in the formation of crystalline Ag–Cu NPs with a face-centered cubic structure. Characterization techniques confirm the presence of functional groups from the plant extract, acting as stabilizing and reducing agents. The synthesized NPs exhibit uniform-sized spherical morphology ranging from 7 to 12 nm. They demonstrate significant antibacterial activity against Staphylococcus aureus and Pseudomonas aeruginosa, inhibiting extracellular polysaccharide secretion in a dose-dependent manner. The Ag–Cu NPs also exhibit potent cytotoxic activity against cancerous HeLa cell lines, with an inhibitory concentration (IC50) of 17.63 µg mL−1. Additionally, they demonstrate strong antioxidant potential, including reducing capability and H2O2 radical scavenging activity, particularly at high concentrations (240 µg mL−1). Overall, these results emphasize the potential of A. lanata plant metabolite-driven NPs as effective agents against infectious diseases and cancer.

In vivo toxicological assessment of silver nanoparticle in edible fish, Oreochromis mossambicus.

Silver nanoparticles are the extensively utilized among all nanoparticles due to their antibacterial and wound healing properties making them highly suitable for medical and pharmaceutical applications. The field of nanoparticle toxicity is an emerging field and the present study aims to assess the biochemical, hematological and genotoxicity in Oreochromis mossambicus exposed to different concentrations of silver nanoparticles for 7 and 14days. Silver nanoparticles were synthesized by reduction of silver nitrate using trisodium citrate and was characterized using X-ray diffraction, SEM, HRTEM and DLS. Hematological parameters like RBC, WBC, Hb, HCT and MCV and for biochemical analysis, antioxidant enzymes SOD, CAT and GPX and serum enzymes AST, ALT, ACP, ALP and LDH were analyzed. Genotoxicity was studied using comet assay. Results obtained showed decrease in erythrocytes, HCT, Hb and MCV while an increase was noted in WBC on day 7 and 14. The antioxidant enzymes SOD, CAT and GPx showed a decrease and the lipid peroxidation product MDA was elevated. The serum enzymes AST, ALT, ACP ALP and LDH showed an increased activity when compared to control. DNA damage was evident by an increase in % TDNA. The results indicate hematological, biochemical and genotoxicity of silver nanoparticles that might be mediated through ROS generation in O. mossambicus.

Establishing a productive heterogeneous catalyst based on silver nanoparticles supported on a crosslinked vinyl polymer for the reduction of nitrophenol.

The treatment of toxic nitrophenols in industrial wastewater is urgently needed from environmental, health, and economic points of view. The current study addresses the synthesis of the crosslinked vinyl polymer poly(acrylonitrile-co-2-acrylamido-2-methylpropane sulfonic acid) (poly(AN-co-AMPS)) through free radical copolymerization techniques using acrylonitrile (AN) and 2-acrylamido-2-methylpropane sulfonic acid (AMPS) monomers with different ratios and potassium persulfate (KPS) as an initiator in an aqueous medium. The prepared copolymer was utilized as a supporting matrix for silver nanoparticles (AgNPs) via the chemical reduction of silver nitrate within the copolymer framework. Different techniques were employed to characterize the prepared poly(AN-co-AMPS) and Ag/poly(AN-co-AMPS) composites, such as Fourier transform infrared (FTIR) spectroscopy, thermal gravimetric analysis (TGA), X-ray diffraction (XRD), transmission electron microscopy (TEM), and Brunauer-Emmett-Teller (BET) analysis. The results exhibit that silver metal was excellently dispersed across the surface of poly(AN-co-AMPS) without any agglomeration, presenting as nanocrystals with an average particle size equal to 6.21 nm. Also, BET analysis confirmed that the Ag/poly(AN-co-AMPS) composite exhibits mesoporous characteristics with a surface area of 59.615 m2 g-1. Moreover, the Ag/poly(AN-co-AMPS) composite was effectively applied as a heterogeneous catalyst for the catalytic reduction of hazardous 4-nitrophenols (4-NP) with a rate constant equal to 0.28 min-1 and half-life time equal to 2.47 min to a less toxic compound in the presence of NaBH4 as a reductant. Furthermore, the reusability experiment confirmed the excellent stability of Ag/poly(AN-co-AMPS). The catalyst can be easily separated from the reaction mixture using a simple centrifuge and directly reused for up to four successive cycles without a remarkable decrease in its catalytic activity. The conversion percentage of 4-NP after the four cycles was found to be 93%.

Eco-friendly preparation and characterization of high-performance electrothermal graphene-AgNPs/lignocellulose composites.

Graphene-based (Gr-based) electrothermal heaters, due to their light weight, low electrical resistance, high thermal conductivity, and easy accessibility, have attracted widespread attention in the field of electrothermal heating. To achieve a high steady-state temperature in electrothermal heaters under low voltage, here we constructed a Gr-based film with low electrical resistance. Firstly, we employed non-toxic vitamin C to reduce silver nitrate for the in situ chemical deposition of silver nanoparticles (AgNPs) on the Gr surface. The SEM results confirmed that the AgNPs were uniformly deposited on the Gr surface. The synergistic interaction between AgNPs and Gr provided high-speed electrons transport paths for the film. On the other hand, we employed biodegradable lignocellulose fiber (LCF) as a dispersant and film-forming agent. The aromatic ring structure of LCF interacts with Gr via π-π interactions, aiding the dispersion of Gr in aqueous solutions. SEM results revealed that LCF permeated through the surfaces and interstices of the two-dimensional Gr sheets, providing mechanical support for the composite film. This approach enables the creation of freestanding Gr-AgNPs/LCF electrothermal composites. The resistivity and electrothermal results demonstrated that the obtained 20 wt% Gr-based composite film possessed low electrical resistance (5.4 Ω sq-1) and exhibited an outstanding saturated temperature of 214 °C under a very low input voltage of 7 V. The preparation method of this Gr-based composite film is simple, easy to operate, and environmentally friendly, providing a new reference for the preparation of eco-friendly and high-performance resistance heating electronics.

Interactions between intermediates in the preparation of silver nanocubes and their impact on the final morphology

The exceptional qualities of silver nanocubes make them ideal for diverse applications in healthcare, electronics, energy, and environmental protection. Studying their growth morphology is crucial for precise synthesis control, property optimization, and sustainable production methods.In this paper, silver nanocubes were prepared through the reduction of silver nitrate using polyvinylpyrrolidone and sodium chloride as additives, with ethylene glycol and polyethylene glycol serving as reducing agents and solvents. The size and shape of these nanoparticles are significantly influenced by the concentration of the precursor and the amount of water in the reaction mixture. These two factors play distinct roles in altering the nucleation and growth processes of the silver nanocubes. Specifically, the precursor concentration determines the rate of nucleation, thus impacting whether the nanoparticles grow through coalescence or Ostwald ripening. Conversely, the water content modulates the reduction rate of silver ions, which in turn dictates whether the reaction occurs under thermodynamic or kinetic control. This investigation enhances our comprehension of the nucleation and growth mechanisms associated with silver nanocubes and provides valuable insights for the one-pot synthesis of uniformly-sized silver nanoparticles, extending beyond the realm of silver nanocubes.

Optimizing the Synthesis of Folic Acid Conjugated Silver Nanoparticles by Box-Behnken Design to Target Breast Cancer Cells

In this study, the synthesis of folic acid conjugated silver nanoparticles (FA&AgNPs) was optimized. FA&AgNPs were synthesized by reduction of silver nitrate with folic acid, which is widely used to target folate receptors in cancer cells. Five independent variables (stirring speed, AgNO3 concentration, folic acid concentration, AgNO3 volume/folic acid volume, and temperature) that were effective on silver nanoparticle synthesis were determined. Based on the independent variables, an experimental plan consisting of 46 experiments was created using the Box-Behnken design (BBD). Nanoparticle formation, physical color change, UV-Vis absorption spectroscopy, Dynamic Light Scattering (DLS) analysis, and Fourier Transform Infrared (FTIR) analysis were evaluated. The mean particle size and zeta potential of FA&AgNPs produced under optimized conditions were measured as 207±4.3 nm and -51.6 mV±2.5, respectively. Cytotoxicity tests were performed to evaluate the anticancer activity of FA&AgNPs in breast cancer cell lines. The IC50 values for MDA-MB-231 breast cancer cells at 24 hours and 48 hours were 20.0 µg/mL and 16.9 µg/mL, respectively, and 26.3 µg/mL and 31.5 µg/mL for MCF-7 cells. The findings indicated that FA&AgNPs have the potential to be an effective anticancer agent in breast cancer cells.

Heat shock proteins capped biocompatible silver nanoparticles and their notable organic waste pollutants removal efficacy

Highly stable nano scale silver nanoparticles synthesis by the algal biomass was recorded at 48 h. UV visible absorption spectra demonstrate the sharp peak at 420 nm specific to silver nanoparticles, and the peak at 220–240 nm reveals the presence of proteins. Heat shock proteins are mainly enzymes produced in response to the heat treatment of algal biomass responsible for reducing silver nitrate into silver nanoparticles. High crystalline phase of the silver nanoparticles was confirmed by X ray diffraction (XRD) showed four major distinct diffraction peaks [38.068 (1 1 1), 44.28 (2 0 0), 64.34 (2 2 0), 77.41 (3 1 1)] corresponding to four diffraction facets of silver. Particles morphology by scanning electron microscopy (SEM) showed nanoscale particles with a size ranging from 55 - 80 nm. Synthesized nanoparticles were screened for waster water treatment efficacy against brewery waste water which was represented as treatment efficacy (TE). In the case of pH, the nanoparticles treatment group revealed 45.0%,76.0% and 92.0% TE at 10, 20 and 30 days. A sharp increase in TE was also noticed in the remaining tested parameters. Silver nanoparticles were not induced any undesirable phytotoxic effect on the tested plants by recording complete seedlings' emergence parameters and no impact on the antioxidants profile. No sign of toxic effect on the selected biofertilisers; biocontrol agents in the nanoparticle's treatment have proved the best compatibility. No impact on the enzyme activity of all the tested enzymes confirmed the best compatibility.

Eco Friendly Synthesis of Silver Oxide Nanoparticles from Borassus Flabellifer Fiber and Its Antibacterial Activity Against Representative Micro Organisms

Abstract The present study reports an easy eco-friendly, cost efficient, and rapid method for the synthesis of silver nanoparticles (Ag NPs) using palm sprouts as reducing cum capping agent. Green synthesis of silver nanoparticles was successfully performed using palm sprouts plant extract via a simple and cheaper eco-friendly method. Palm sprouts extract reduces silver nitrate to silver nanoparticles. The resulting materials were analyzed by Fourier-transform infrared spectroscopy (FTIR), Scanning Electron Microscopy (SEM), and X-ray Diffraction (XRD) analysis. FT-IR spectrum confirms the presence of various functional groups in the active biomolecules, it acts as a capping agent for the nanoparticles. The morphology of this sample was analyzed through SEM and the presence of silver was confirmed accordingly. The green synthesized Ag NPs exhibited an excellent antibacterial activity against E. coli and P. aeruginosa and B. subtilis and S. aureus besides imparting efficient antimicrobial activity against pathogenic bacteria as well.

Green syntheses of silk fibroin/wool keratin-protected Au[sbnd]Ag nanoclusters with enhanced fluorescence for multicolor and patterned anti-counterfeiting

Counterfeiting is a serious worldwide issue that threatens human health and economic security. How to apply anti-counterfeiting techniques to textile materials remains a great challenge. Herein, we report bimetallic AuAg nanoclusters (NCs) synthesized by one-step reduction of chloroauric acid (HAuCl4) and silver nitrate (AgNO3) with wool keratin (WK) as reducer and silk fibroin (SF) as stabilizer. The strongest orange-red fluorescence under ultraviolet light as well as the highest zeta potential absolute values of −27.97 mV were simultaneously realized in the optimal proportion Au-AgNCs2 (WK/SF is 3/2), which was further processed to a series of anti-counterfeiting films by blending with SF, silk sericin (SS), and polyvinyl alcohol (PVA). After successfully being numbered into fifteen colors, a dark blue-orange-dark red-dark blue cyclic fluorescent anti-counterfeiting color chart was designed. In addition, a two-Maxwell-unit model was constructed to assist with the microstructure analysis, which found that the formation of hydrogen bonds and the secondary structure transition from α-helices to β-sheets during stretching were responsible for improving the mechanical properties and the two-staged fracture curves of films, respectively. Finally, a patterned and multicolor fluorescence anti-counterfeiting fabric application was demonstrated by combining the color chart and screen printing, indicating the great potential in textile anti-counterfeiting.

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.

Rapid production of silver nanofibers using a self-reducing solution

Silver nanofibers (Ag NFs) have gained considerable attention because of their high transmittance resulting from the size effect, excellent electrical conductivity, and mechanical properties. However, synthesizing high-quality Ag NFs remains a challenge. This paper reports a novel self-reducing solution that contains platinum nanoparticles for the rapid production of Ag NFs. The method involves generating the precursor NFs and heating them in air, which reduces silver nitrate to Ag NFs within a few minutes. The as-prepared solution is characterized by its simple preparation, cost-effectiveness, and broad applicability. Additionally, the use of high-pressure airflow to directly spin the solution and a complete self-reduction system that does not depend on external conditions broadens the application prospects of the as-developed solution. Furthermore, we provide insights into the self-reduction mechanism and guidance on the preparation of self-reducing solutions.

Biological properties of experimental dental alginate modified for self-disinfection using green nanotechnology

ObjectivesDisinfection of alginate impression materials is a mandatory step to prevent cross-infection in dental clinics. However, alginate disinfection methods are time-consuming and exert a negative impact on accuracy and mechanical properties. Thus, this study aimed to prepare disinfecting agents (CHX and AgNO3) and silver nanoparticles reduced by a natural plant extract to produce a self-disinfecting dental alginate.MethodsConventional alginate impression material was used in this study. Silver nitrate (0.2% AgNO3 group) and chlorohexidine (0.2% CHX group) solutions were prepared using distilled water, and these solutions were later employed for alginate preparation. Moreover, a 90% aqueous plant extract was prepared from Boswellia sacra (BS) oleoresin and used to reduce silver nitrate to form silver nanoparticles that were incorporated in the dental alginate preparation (BS+AgNPs group). The plant extract was characterized by gas chromatography/mass spectrometry (GC/MS) analysis while green-synthesized silver nanoparticles (AgNPs) were characterized by UV-visible (UV–vis) spectroscopy and scanning electron microscopy (SEM). An agar disc diffusion assay was used to test the antimicrobial activity against Candida albicans, Streptococcus mutans, Escherichia coli, methicillin-resistant and susceptible Staphylococcus aureus strains, and Micrococcus luteus. Agar plates were incubated at 37 ± 1 °C for 24 h to allow microbial growth. Diameters of the circular inhibition zones formed around each specimen were measured digitally by using ImageJ software.ResultsChemical analysis of the plant extract revealed the presence of 41 volatile and semi-volatile active compounds. UV–Vis spectrophotometry, SEM, and EDX confirmed the formation of spherical silver nanoparticles using the BS extract. CHX, AgNO3, and the BS+AgNPs modified groups showed significantly larger inhibition zones than the control group against all tested strains. BS+AgNPs and CHX groups showed comparable efficacy against all tested strains except for Staphylococcus aureus, where the CHX-modified alginate had a significantly higher effect.Conclusions and clinical relevanceCHX, silver nitrate, and biosynthesized silver nanoparticles could be promising inexpensive potential candidates for the preparation of a self-disinfecting alginate impression material without affecting its performance. Green synthesis of metal nanoparticles using Boswellia sacra extract could be a very safe, efficient, and nontoxic way with the additional advantage of a synergistic action between metal ions and the phytotherapeutic agents of the plant extract.

Cytocompatibility, antibacterial, and corrosion properties of chitosan/polymethacrylates and chitosan/poly(4-vinylpyridine) smart coatings, electrophoretically deposited on nanosilver-decorated titania nanotubes.

The development of novel implants subjected to surface modification to achieve high osteointegration properties at simultaneous antimicrobial activity is a highly current problem. This study involved different surface treatments of titanium surface, mainly by electrochemical oxidation to produce a nanotubular oxide layer (TNTs), a subsequent electrochemical reduction of silver nitrate and decoration of a nanotubular surface with silver nanoparticles (AgNPs), and finally electrophoretic deposition (EPD) of a composite of chitosan (CS) and either polymethacrylate-based copolymer Eudragit E 100 (EE100) or poly(4-vinylpyridine) (P4VP) coating. The effects of each stage of this multi-step modification were examined in terms of morphology, roughness, wettability, corrosion resistance, coating-substrate adhesion, antibacterial properties, and osteoblast cell adhesion and proliferation. The results showed that the titanium surface formed nanotubes (inner diameter of 97 ± 12 nm, length of 342 ± 36 nm) subsequently covered with silver nanoparticles (with a diameter of 88 ± 8 nm). Further, the silver-decorated nanotubes were tightly coated with biopolymer films. Most of the applied modifications increased both the roughness and the surface contact angle of the samples. The deposition of biopolymer coatings resulted in reduced burst release of silver. The coated samples revealed potent antimicrobial activity against both Gram-positive and Gram-negative bacteria. Total elimination (99.9%) of E. coli was recorded for a sample with CS/P4VP coating. Cytotoxicity results using hFOB 1.19, a human osteoblast cell line, showed that after 3 days the tested modifications did not affect the cellular growth according to the titanium control. The proposed innovative multilayer antibacterial coatings can be successful for titanium implants as effective postoperative anti-inflammation protection.

Ultrasensitive Fluorescence Platform Based on AgNPs In Situ-Incorporated Zr-MOFs for the Detection of Organophosphorus Pesticides.

Organophosphorus pesticides (OPPs) are extensively used in agricultural production, and the contamination caused by their residues has raised significant concerns regarding potential threats to human health. Herein, a novel fluorescence nanoprobe based on an enzyme-mediated silver nanoparticle-modified metal organic framework (AgNPs@PCN-224) was successfully prepared for the rapid detection of OPPs. Initially, AgNPs@PCN-224 were synthesized by reducing silver nitrate (AgNO3) using sodium borohydride (NaBH4) embedded into luminescent PCN-224. This triggered the inner filter effect, leading to fluorescence quenching. Meanwhile, under the catalysis of acetylcholinesterase (AChE) and choline oxidase (CHO), acetylcholine (ATCh) was decomposed to hydrogen peroxide (H2O2), which could destroy AgNPs to form Ag+ released from PCN-224 for fluorescence recovery. Instead, fenitrothion, an OPP, inhibited AChE activity, allowing the quenched fluorescence to be reactivated. Under the current optimum conditions, the fluorescence intensity had a good correlation (Y = -728.5370X + 2178.4248, R2 = 0.9869) over a dynamic range of fenitrothion concentrations from 0.1 to 500 ng/mL, with an LOD of 0.037 ng/mL. In addition, the anti-interference ability and robustness of the proposed sensor was verified for the monitoring of fenitrothion in tea with recoveries of 87.67-103.72% and the relative standard deviations (RSD) < 5.43%, indicating that the system has excellent prospects for OPP determination in practical applications. Furthermore, this work provides a universal platform for screening other enzyme inhibitors to detect OPPs.

Colorimetric Sensor Based AgNPs for the Detection of Cyanide using UV‐Vis Spectrophotometry

AbstractCyanide (CN−) is known to be a very harmful ion that may accumulate in the air, soil and water, and become a critical risk to organisms, even at trace levels. Hence, it is very critical to develop sensitive and accurate analytical methods for the determination of this anion. In this study, a highly sensitive and simple approach was developed for the quantitative determination of cyanide by UV‐Vis spectrophotometry with the aid of synthesized silver nanoparticles (AgNPs) solutions. AgNPs are promising probes frequently used in the determination of both organic and inorganic pollutants. The AgNPs were prepared by reducing silver nitrate (AgNO3) with sodium borohydride (NaBH4) in the presence of Triton X‐100 as a stabilizer. The UV‐Vis absorption spectra showed that the interaction between cyanide ions and AgNPs made significant decreases in the absorption peak of the surface plasmon resonance (SPR) band at 405 nm. The developed colorimetric sensor exhibited exceptional sensing towards cyanide ions with good linearity in the range of 0.5 and 3.5 mM. The limit of detection (LOD) and the limit of quantification (LOQ) were estimated as 0.09 and 0.29 mM, respectively. Moreover, the proposed colorimetric method was successfully applied to different water samples.

Study of Photo-transformation of Ag Nanoparticles under Green LEDs Light Source and their Changes Induced by Z-scan Technique

Background: The study of metallic nanoparticles is important since they present nonlinear optical properties crucial for modern photonic science and technology. Moreover, their mechanical, chemical, and optical properties are different from those presented with respect to volumetric material. Said properties can be adjusted by controlling the size and shape of the studied nanoparticles, and various methodologies have been developed to obtain nanoparticles by chemical and physical means. Methods: Spherical nanoparticles were synthesized by chemically reducing silver nitrate, sodium borohydride, and sodium citrate precursors. Different amounts of silver nitrate were added to the original spherical nanoparticles and then exposed to a green LED light source to convert the spherical nanoparticles to triangular prisms. The changes in the samples were monitored using absorption spectra obtained with a UV-Vis spectrophotometer. The nonlinear refractive index was determined with Z-scan measurements, and a scanning electron microscope was used to observe the silver nanoparticles before and after laser irradiation. Results: The absorption spectra show a band of around 418 nm for the original spherical nanoparticles, which shifted to blue after the irradiation with green LED light. Furthermore, a new band was obtained, centered around 565 nm, which indicates the presence of triangular prisms. From SEM images, it was confirmed that the spherical nanoparticles were transformed into triangular nanoprisms. The non-linear (negative) refractive index depends on the shape and number of nanoparticles; however, using the Z-scan technique caused photo-melting and photofragmentation of the triangular prisms, which was corroborated by SEM images. Conclusion: These results suggest that the shape and amount of AgNPs can be controlled with excess silver ions and irradiation time. In addition, the Z-scan technique causes photo-melting and photo-fragmentation of AgNPs, and their nonlinear refraction index is negative due to thermal origin.

Amine-functionalized reduced graphene oxide-supported silver nanoparticles for superior catalytic reduction of organic pollutants.

In this work, a simple and environmentally friendly approach has been followed to synthesize amine-functionalized reduced graphene oxide (RGO)-supported silver nanoparticle (AgNPs) having superior catalytic efficiency towards the reduction of organic pollutants. RGO/AgNPs nanohybrid was synthesized by a one-pot hydrothermal reduction of silver nitrate in the presence of amino-propyl trimethoxy silane (APTMS)-functionalized graphene oxide (GO) nanosheets. The structural and morphological characterization of as-synthesized RGO/AgNPs nanohybrid was done by using XRD, SEM, TEM, FT-IR, and Raman spectroscopy techniques. APTMS plays an important role in controlling the size of anchored AgNPs on the nanohybrid in the present study. The -NH2 groups on the surface of APTMS-modified GO function as effective and well-organized nucleation centers facilitating uniform growth of discrete and smaller-sized spherical AgNPs on the surface of RGO nanosheets. In the absence of APTMS, the nanohybrid comprised of bigger-sized AgNPs with few hundred of nanometers in dimension. The catalytic efficiency of RGO/AgNPs nanohybrid was evaluated for the reduction of two model organic pollutants: 4-nitrophenol (4-NP) and methylene blue (MB). Due to the synergistic effects of RGO, APTMS, and Ag components, RGO/AgNPs nanohybrid developed in the present study exhibited superior catalytic activity towards the reduction of 4-NP and MB in comparison with previously reported graphene/graphene oxide/reduced graphene oxide-supported AgNPs catalysts. The catalytic reduction of 4-NP and MB followed pseudo-unimolecular kinetics and the rate constants were found to be 18.83 × 10-3 s-1 and 131.5 ×10-3 s-1 respectively for 4-NP and MB. Furthermore, RGO/AgNPs nanohybrid showed admirable recyclability with negligible loss in its activity until five recycle runs. The superior catalytic activity, favorable kinetic parameters, and sustained catalytic efficiency after recycling make RGO/AgNPs nanohybrid a promising catalyst for the reduction of organic pollutants in environmental remediation.

Planophila laetevirens-Mediated Synthesis of Silver Nanoparticles: Optimization, Characterization, and Anticancer and Antibacterial Potentials.

Algal-mediated synthesis of nanoparticles (NPs) opens the horizon for green and sustainable synthesis of NPs that can be used in many fields, such as medicine and industry. We extracellularly synthesized silver NPs (Ag-NPs) using the novel microalgae Planophila laetevirens under optimized conditions. The isolate was collected from freshwater/soil, purified, morphologically identified, and genetically identified using light, inverted light, scanning electron microscopy, and 18S rRNA sequencing. The phytochemicals in the algal extract were detected by GC-MS. Aqueous biomass extracts and cell-free media were used to reduce silver nitrate to Ag-NPs. To get small, uniformly shaped, and stable Ag-NPs, various abiotic parameters, including precursor concentration, the ratio between the reductant and precursor, temperature, time of temperature exposure, pH, illumination, and incubation time, were controlled during the synthesis of Ag-NPs. B-P@Ag-NPs and S-P@Ag-NPs (Ag-NPs synthesized using biomass and cell-free medium, respectively) were characterized using UV-vis spectroscopy, transmission electron microscopy, scanning electron microscopy, energy-dispersive X-ray analysis (EDX) and mapping, Fourier transform infrared (FTIR) spectroscopy, and a zeta sizer. S-P@Ag-NPs had a smaller size (10.8 ± 0.3 nm) than B-P@Ag-NPs (19.0 ± 0.6 nm), while their shapes were uniform quasispherical (S-P@Ag-NPs) and spherical to oval (B-P@Ag-NPs). EDX and mapping analyses demonstrated that Ag was the dominant element in the B-P@Ag-NP and S-P@Ag-NP samples, while FTIR revealed the presence of O-H, C-H, N-H, and C-O groups, indicating that polysaccharides and proteins acted as reductants, while polysaccharides/fatty acids acted as stabilizers during the synthesis of NPs. The hydrodynamic diameters of B-P@Ag-NPs and S-P@Ag-NPs were 37.7 and 28.3 nm, respectively, with negative charges on their surfaces, suggesting their colloidal stability. Anticancer activities against colon cancer (Sw620 and HT-29 cells), breast cancer (MDA-MB231 and MCF-7 cells), and normal human fibroblasts (HFs) were screened using the MTT assay. B-P@Ag-NPs and S-P@Ag-NPs had a greater antiproliferative effect against colon cancer than against breast cancer, with biocompatibility against HFs. The biocidal effects of the B-P@Ag-NPs and S-P@Ag-NPs were evaluated against Escherichia coli, Bacillus cereus, and Bacillus subtilis using agar well diffusion and resazurin dye assays. B-P@Ag-NPs and S-P@Ag-NPs caused higher growth inhibition of Gram-negative bacteria than of Gram-positive bacteria. B-P@Ag-NPs and S-P@Ag-NPs synthesized by P. laetevirens are promising antitumor and biocidal agents.