Surface Plasmon Resonance Peak Research Articles

Synthesis of Silver Nanomaterials Capping by Fruit-mediated Extracts and Antimicrobial Activity: A Critical Review

Natural silver nanoparticles are currently being used innovatively by a unique simple route. Different bio-mediated fruit peel extracts were used to produce silver nanoparticles (AgNPs) and explore the synthesis of environmentally friendly aspects. To produce biodegradable AgNPs various bio-mediated fruit peel extracts function as reducing and capping agents in the synthesis route. It was discovered that several fruit peel extracts act as a capping agent and silver ions (Ag+ to Ag0). Due to reduction, the reaction changes the hydrogel's distinctive hue to a reddish-brown appearance. UV-visible spectra of the AgNPs showed a distinctive surface plasmon resonance (SPR) peak around 460.0 nm. Using X-ray diffraction, the crystallographic nature was discovered with brags diffraction. FT-IR confirmed silver ions function as a capping and reducing agent from peel extract. The transmission electron microscope confirmed that the average size of the nanoparticles was below 100.0 nm and internal morphology. These nanoparticles' ability to combat bacteria, algae and fungi was also well investigated. This manuscript highlights the different bio-mediated and peal extracts that are efficient in producing AgNPs and their function for promising antimicrobial activity.

A novel approach to enhance the ionic conductivity of silver nanoparticles incorporated PVA:NaBr polymer electrolyte films via fast neutron irradiation

This study investigates the unprecedented impact of fast neutron irradiation on the structural, electrical, and morphological properties of solid polymer electrolytes (SPEs). The SPE, a poly (vinylalcohol) (PVA)-sodium bromide (NaBr) based matrix with the incorporation of silver nanoparticles (AgNPs), was prepared via a solution casting method and subjected to various time intervals of fast neutron irradiation. X-ray diffraction (XRD) analysis revealed a distinct trend in the polymer electrolyte sample's amorphous phase, with decreased levels at lower neutron fluence and augmented levels at higher fluences. Fourier transform infrared (FTIR) spectroscopy highlighted plausible interactions leading to chain scission and cross-linking. Optical investgations below 300 nm exhibited increased absorbance and a shifted position of the surface plasmon resonance peak correlated with AgNPs. Validation of structural changes in the Ag-incorporated PVA-NaBr system was supported by reduced bandgap and elevation in Urbach energy, corroborating FTIR findings. Enhanced thermal stability was confirmed using thermogravimetric (TGA) analysis. Morphological modification upon irradiation were evident via Field emission scanning electron microscope (FESEM). Transport properties evaluated by Nyquist plot fitting showcased escalating room temperature conductivity with neutron fluence, and the highest conductivity obtained was 4.38 × 10−3 S/cm, an order higher than the pristine sample. Transference number measurements (TNM) indicated that the primary charge carriers are ions rather than electrons. This novel approach confirms that neutron irradiation can be used as a potential way to obtain highly conductive polymer electrolyte films.

Application of Green Synthesized Silver Nanoparticles for Dye Wastewater Treatment

A facile one-pot synthesis of silver nanoparticles (AgNPs) was achieved using the ethanolic extract of Cavendish banana florets as source of reducing agents for the conversion of Ag+ to Ag. The appearance of surface plasmon resonance peak between 410–435 nm in the UV Vis spectra confirmed the formation of AgNPs. The effects of different reaction conditions on the size and concentration of AgNPs were evaluated. The optimum conditions identified were pH 7 at 80 °C. Transmission electron microscopy (TEM) revealed spherical AgNPs with a mean particle size of 13.55 nm. On the other hand, energy-dispersive X-ray (EDX) analysis confirmed the presence of silver (Ag) as the bulk element (87.25%). Other elements such as carbon (C) and oxygen (O) are attributed to the capping agents of AgNPs which agrees with the results in the Fourier-transform infrared spectroscopy (FTIR) analysis. The optimized AgNPs were used for dye degradation using methyl orange (MO) as the model dye under acidified conditions. The maximum MO dye degradation of 96.07% and 77.32% at pH 1.5 and 2 were achieved after 10 min and 1320 min, respectively. This highlights the potential use of green-synthesized AgNPs for dye wastewater treatment.

Size-Dependent Surface Plasmon Resonance of Green Synthesized Gold Nanoparticles Using <i>Mangifera indica</i> Fruit Peel Extract

Gold nanoparticles (AuNPs) have been studied for various applications due to their adjustable surface plasmon resonance (SPR) properties and facile synthesis. AuNP production has predominantly relied on synthetic chemicals to reduce and stabilize gold precursors. There is an increasing demand for environmentally friendly synthesis methods due to ecological concerns. This work introduced a green synthesis approach using Mangifera indica fruit peel extract. Obtained through maceration of dried fruit peels, this extract served as a reducing agent for gold precursors at 80°C. We obtained varying sizes of AuNPs by manipulating the initial concentration of gold ions: 0.1mM, 0.25mM, and 0.5mM. The UV-vis spectroscopy results confirmed the signature SPR peak for AuNPs around 530 nm, with peak shifts highly dependent on the gold ion concentration. The dynamic light scattering (DLS) measurements revealed hydrodynamic diameters of 89.5 nm, 121.5 nm, and 144.5 nm for the various concentrations. The Fourier transform (FTIR) analysis identified the role of inherent phenols and flavonoids in gold precursor reduction. This study emphasizes the potential of Mangifera indica fruit peel extract as a viable alternative for AuNP synthesis. This study could possibly boost the utilization of gold nanoparticles towards applications in biology and medicine as well as environmental remediation.

Light-Triggered Reversible Change in the Electronic Structure of MoO3 Nanosheets via an Excited-State Proton Transfer Mechanism.

Light is an attractive source of energy for regulating stimulus-responsive chemical systems. Here, we use light as a gating source to control the redox state, the localized surface plasmonic resonance (LSPR) peak, and the structure of molybdenum oxide (MoO3) nanosheets, which are important for various applications. However, the light excitation is not that of the MoO3 nanosheets but rather that of pyranine (HPTS) photoacids, which in turn undergo an excited-state proton transfer (ESPT) process. We show that the ESPT process from HPTS to the nanosheets and the intercalation of protons within the MoO3 nanosheets trigger the reduction of the nanosheets and the broadening of the LSPR peak, a process that is reversible, meaning that in the absence of light, the LSPR peak diminishes and the nanosheets return to their oxidized form. We further show that this reversible process is accompanied by a change in the nanosheet size and morphology.

Ultra-high sensitivity surface plasmon U-channel photonic crystal fiber for hemoglobin sensing

In order to increase the wavelength response range of the U-channel sensor, a numerical study has been conducted and then the sensing structure has been optimized. A sensor in photonic crystal fiber (PCF) is proposed in which a layer of titanium dioxide is coated on the surface of the U-channel and then coated with a gold film. These two different metal films are mainly used to control the Surface plasmon resonance (SPR) peak and the corresponding resonance wavelength, thus changing the sensor performance. Just below the metal layer are two special air holes on either side. They form a leakage window in the center. In the following sections, the effects of these variables on the sensor will be studied in detail by COMSOL. The modal transmission characteristics of this fiber optic sensor are analyzed in this paper. By analyzing the obtained loss spectrum, the energy variation in the surface plasmon polariton (SPP) mode and the influence of the core mode on the sensing performance of the fiber optic sensor presented, the general rule of the optimized PCF-SPR sensor is deduced. In addition, we can make subtle adjustments to the sensor to improve its sensitivity. We found with the refractive index (RI) ranging from 1.26 to 1.42, the maximum wavelength sensitivity is 7500 nm/RIU, which corresponds to a full width at half maximum (FWHM) of 11.83 nm，a figure of merit (FOM) of 634.1 RIU−1. In addition, we also have discussed the sensor and different concentrations of hemoglobin aqueous solution to detect its RI. It is evident from the results that the sensor demonstrates excellent sensitivity and a wide detection range, which is highly desirable for practical diagnostic purposes. The potential of this sensor for clinical trials and its application to medical diagnostics is promising. Compared with complex traditional methods, the PCF has obvious advantages such as clear structure, simple manufacture, high sensitivity and strong environmental adaptability. Moreover, it has the advantage of wide wavelength response range and has a clear development prospect in the field of biochemical sensing. It has foreseeable potential practical value.

A portable intelligent hydrogel platform for multicolor visual detection of HAase.

Hyaluronidase (HAase) is an important endoglycosidase involved in numerous physiological and pathological processes, such as apoptosis, senescence, and cancer progression. Simple, convenient, and sensitive detection of HAase is important for clinical diagnosis. Herein, an easy-to-operate multicolor visual sensing strategy was developed for HAase determination. The proposed sensor was composed of an enzyme-responsive hydrogel and a nanochromogenic system (gold nanobipyramids (AuNBPs)). The enzyme-responsive hydrogel, formed by polyethyleneimine-hyaluronic acid (PEI-HA), was specifically hydrolyzed with HAase, leading to the release of platinum nanoparticles (PtNPs). Subsequently, PtNPs catalyzed the mixed system of 3,3',5,5'-tetramethylbenzidine (TMB) and H2O2 to produce TMB2+ under acidic conditions. Then, TMB2+ effectively etched the AuNBPs and resulted in morphological changes in the AuNBPs, accompanied by a blueshift in the localized surface plasmon resonance peak and vibrant colors. Therefore, HAase can be semiquantitatively determined by directly observing the color change of AuNBPs with the naked eye. On the basis of this, the method has a linear detection range of HAase concentrations between 0.6 and 40 U/mL, with a detection limit of 0.3 U/mL. In addition, our designed multicolor biosensor successfully detected the concentration of HAase in human serum samples. The results showed no obvious difference between this method and enzyme-linked immunosorbent assay, indicating the good accuracy and usability of the suggested method.

Green synthesis, characterization, and antibacterial activity of silver nano particles against some bacterial isolates

Nanotechnology has emerged as a promising field for the development of novel antibacterial agents with reduced environmental impact. In this study, we present a novel green synthesis approach for the production of silver nanoparticles (AgNPs) using a plant-based extract. These AgNPs were subsequently characterized using various analytical techniques, including UV-Vis spectroscopy, X-ray diffraction (XRD), transmission electron microscopy (TEM), and Fourier-transform infrared spectroscopy (FTIR). UV-Vis spectroscopy confirmed the formation of AgNPs by exhibiting a characteristic surface plasmon resonance peak at around 401 and 420 nm. XRD analysis revealed the crystalline nature of the AgNPs, with distinct diffraction peaks corresponding to the face-centered cubic structure of silver. TEM analysis demonstrated that the synthesized AgNPs were predominantly spherical in shape and exhibited an average size within the nanoscale range. FTIR analysis was employed to elucidate the potential bioactive compounds present in the plant extract responsible for the reduction and stabilization of AgNPs. Furthermore, we evaluated the antibacterial activity of these synthesized AgNPs against a panel of bacterial isolates. All the bacterial isolates were sensitive to the silver nanoparticles. Staphylococcus aureus as found to be most resistant, while E. coli as found to be the most sensitive.

GREEN HYDROTHERMAL SYNTHESIS OF Ag@Guajavapsidium LEAF BIOCHAR NANOCOMPOSITE AND THE EVALUATION OF THE PHOTOCATALYTIC AND ANTIMICROBIAL ACTIVITIES

An Environmental and health concern requires an alternative fabrication route for nanomaterials because of the high toxicity and cost of reagents. In this study, the phyto-fabrication of silver grafted guava leaf extract and biomass biochar nanocomposite was executed using a novel, facile, low cost, sustainable and eco-friendly route. The formation of the nanocomposite was evidenced through UV spectroscopic analysis with surface plasmon resonance peak at 349 nm. The Fourier transform infrared spectroscopy (FTIR) and energy dispersive spectroscopy (EDX) also confirmed the formation of the nanocomposite as illustrated by the spectra change and presence of Ag+ ions on the surface of the nanocomposite respectively. The x-ray diffraction (XRD) and scanning electron microscopy (SEM) confirmed the crystal structure and spherical, porous nature with a size range of 25 to 40 nm of the nanocomposite respectively. The potential of nanocomposite in the removal of MBwas evident under different conditions as it reached nearly 100% under the optimum reaction conditions (methylene blue (MB) concentration; 10 ppm, a dose of Ag/extract /biochar; 0.01 g, temperature; 25 °C). The novel nanocomposite regeneration and reusability was promising, as the removal efficiency of MB from solution after five cycle reuse was above 80 %. Antimicrobial evaluation of the nanocomposite using Escherichia coli Klebsiella pneumonia, staphylococcus aureus and salmonella specie revealed that it is an excellent antimicrobial agent with 9, 8, 15 and 5 mm zones of inhibition respectively.

Biogenic synthesis of silver nanoparticles using Rubus fruticosus extract and their antibacterial efficacy against Erwinia caratovora and Ralstonia solanacearum phytopathogens.

In the current research, we produced green, cost-effective, eco-friendly silver nanoparticles using a single-step approach. Plants are considered highly desirable systems for nanoparticle synthesis because they possess a variety of secondary metabolites with significant reduction potential. In the current research, the dried leaf extract of Rubus fruticosus was utilized as a capping and reducing agent for the fabrication of silver nanoparticles, to prepare reliable biogenic silver nanoparticles and subsequently to investigate their potential against some common phytopathogens. The prepared silver nanoparticles were exploited to quantify the total flavonoid content (TFC), total phenolic content (TPC) and DPPH-based antioxidant activity. Different concentrations of aqueous extracts of plant leaves and silver nitrate (AgNO3) were reacted, and the color change of the reactant mixture confirmed the formation of Rubus fruticosus leaf-mediated silver nanoparticles (RFL-AgNPs). A series of characterization techniques such as UV-vis spectroscopy, transmission electron microscopy, energy dispersive X-ray analysis and X-ray diffraction revealed the successful synthesis of silver nanoparticles. The surface plasmon resonance peak appeared at 449 nm. XRD analysis demonstrated the crystalline nature, EDX confirmed the purity, and TEM demonstrated that the nanoparticles are mostly spherical in form. Furthermore, the biosynthesized nanoparticles were screened for in vitro antibacterial activity, antioxidant activity, and total phenolic and flavonoid content. The nanoparticles were used in different concentrations alone and in combination with plant extracts to inhibit Erwinia caratovora and Ralstonia solanacearum. In high-throughput assays used to inhibit these plant pathogens, the nanoparticles were highly toxic against bacterial pathogens. This study can be exploited for planta assays against phytopathogens utilizing the same formulations for nanoparticle synthesis and to develop potent antibacterial agents to combat plant diseases.

Biosynthesis and characterization of silver nanoparticles using polysaccharides from Caulerpa racemosa and evaluation of their antioxidant, antibacterial, and anticancer activities

In recent years, using biological materials to synthesize metallic nanoparticles has emerged as an efficient and cost-effective approach. This work synthesized silver nanoparticles (AgNPs) from Caulerpa racemosa (Cr) - Polysaccharide (Ps). UV–vis spectroscopy examined the synthesised Cr-Ps-AgNPs, revealing a colour shift and a surface plasmon resonance peak at 450 nm. The Fourier transform infrared spectroscopy is used to detect functional groups within the polysaccharide and to investigate nanoparticle interactions. Scanning Electron Microscopy revealed that the biosynthesized Cr-AgNPs varied in size from 32 to 77 nm. X-ray diffraction confirmed that the Cr-Ps-AgNPs were crystalline. Also, dynamic light scattering showed that the Cr-Ps-AgNPs particles, which were biosynthesized nanoparticles, had a size distribution that was polydisperse, with an average diameter of 42.8 nm. In a dose-dependent manner, the biosynthesized Cr-Ps-AgNPs demonstrate high antioxidant activity in the DPPH, reducing power, and total antioxidant scavenging tests. The antibacterial activity of Cr-Ps-AgNPs against Pseudomonas aeruginosa, Klebsiella pneumonia, Staphylococcus aureus, and Streptococcus pyogenes was assessed using an agar well diffusion test, which revealed dose-dependent activity. The cytotoxicity investigation showed a dose-dependent activity against breast cancer cells (MCF-7), with an inhibitory concentration (IC50) of 38 μg/mL. The results of this study show that synthesised Cr-Ps-AgNPs exhibit antioxidant, antibacterial, and anticancer properties.

Microstrain effects of laser-ablated Au nanoparticles in enhancing CZTS-based 1 Sun photodetector devices.

Copper zinc tin sulfide (CZTS) thin films were synthesized on soda lime glass using pulsed laser deposition (PLD) at room temperature. Introducing gold nanoparticles (AuNPs) in a sandwich structure led to increased CZTS particle size and a shift in the localized surface plasmon resonance (LSPR) peak of the AuNPs, influenced by different laser energy levels. The absorption measurements revealed intriguing behavior across the visible and near-infrared (NIR) regions, making these films appealing for 1 Sun photodetectors. Furthermore, the presence of AuNPs in the sandwich structure reduced microstrain effects, measuring 1.94 × 10-3 compared to 3.38 × 10-3 in their absence. This reduction directly enhances carrier transport, which is particularly beneficial for accelerating the performance of photodetector devices. This effect of AuNPs also contributed to higher dielectric coefficients, further improving the photodetector performance. Under 1 Sun illumination conditions, this enhancement resulted in a rapid rising time of 95.4 ms, showcasing the potential for faster photodetection.

Sustainable green synthesis of Hedychium coronarium leaf extract-stabilized silver nanoparticles and their applications: colorimetric sensing of Sn2+ and Hg2+ and antifungal and antimicrobial properties.

Hedychium coronarium (Hc) (commonly known as Gulbakawali) leaf extract was used for the stable and sustainable green synthesis of silver nanoparticles (Hc-AgNPs), which were biodegradable and non-toxic. Hedychium coronarium leaf extract was used as a reducing agent to stabilize the Hc-AgNPs by converting Ag+ to Ag0 without adding any capping agent. It demonstrated stability for up to six months, and no agglomeration was observed. The Hc-AgNPs were characterized using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), ultraviolet-visible spectrophotometry, and fluorescence spectroscopy analysis. The UV-visible spectrum supported the formation of stable Hc-AgNPs by displaying a strong surface plasmon resonance (SPR) peak at 440 nm. FT-IR spectra showed the functional groups present in the leaf extract of Hedychium coronarium, which was the primary source of secondary metabolites attached to Ag0. XRD analysis revealed a distinct 2θ peak of Hc-AgNPs at 38.15°, indicating a face-centred cubic structure with a crystallite size of 22.6 ± 1 nm at the (111) plane. Moreover, TEM demonstrated the spherical morphology of the Hc-AgNPs with an average particle size of 22.42 ± 1 nm. The photophysical characteristics of the Hc-AgNPs, as highlighted by their UV-vis and fluorescence characteristics, revealed their semiconducting nature with an impressive band gap (E g) value of 3.78 eV. Fascinatingly, the fluorescence activity of Hc-AgNPs at 504 nm showed a broad emission band corresponding to the absorption band at 251 nm. We performed the selective colorimetric sensing of Sn2+ metal ions using Hc-AgNPs, which demonstrated a detection limit of 10-3 M, suggesting their potential as very good solid biosensors. Interestingly, the Hc-AgNPs showed antifungal activity, which has not been reported before. Specifically, the results showed that the Hc-AgNPs had a higher fungitoxicity effect against Aspergillus flavus (59.58 ± 3.68) than against Fusarium oxysporum (57.93 ± 4.18). The antibacterial activity of the Hc-AgNPs was evaluated against three Gram-negative phytopathogenic bacteria: Xanthomonas oryzae (X. oryzae), Ralstonia solanacearum (R. solanacearum), and Erwinia carotovora (E. carotovora), showing effective inhibition zones of 16.33 ± 0.57, 15.33 ± 0.57, and 14.33 ± 0.57 mm, respectively. These results indicate that the Hc-AgNPs could inhibit these phytopathogenic bacteria with varying degrees of effectiveness in the order of X. oryzae > R. solanacearum > E. carotovora.

Tuning of chemical interface damping in single gold nanorods through pH-dependent host-guest interactions using cucurbit[6]uril.

Chemical interface damping (CID) in gold nanorods (AuNRs) arises from direct hot electron transfer from Au to adsorbed molecules. Despite recent studies on CID, its tunability in single AuNRs remains challenging. Herein, we present a method for in situ control of CID in single AuNRs using pH-dependent host-guest supramolecular interactions. We employ cucurbit[6]uril (CB[6]), a well-known host molecule capable of encapsulating and releasing guest molecules, along with bis(3-aminopropyl)amine (BAPA) as guest molecules forming a complex with CB[6] (CB[6]-BAPA). CID is induced by attaching the CB[6]-BAPA complex on AuNR surfaces through a strong Au-amine interaction. In addition, in situ tuning of CID is achieved by releasing CB[6] from the complex using a NaOH solution. Successful CB[6]-BAPA complex formation, their attachment onto AuNRs, and CB[6] release from the complex are confirmed through changes in the localized surface plasmon resonance (LSPR) peak and LSPR linewidth, alongside mass analysis. Therefore, this study offers a new method for in situ CID tuning using CB[6]-based pH-sensitive host-guest interactions in individual AuNRs. This study can be further used in CB[6]-based photochemical processes and biosensing studies.

Comparative study of well diffusion and disc diffusion method to investigate the antibacterial properties of silver nanoparticles synthesized from Curcuma longa extracts

Green synthesis method for the preparation of silver nanoparticles (AgNPs) using Curcuma longa extracts as reducing and stabilizing agents was studied. The optimization of the synthesis was determined by varying the weight of the extracts, the AgNO3 concentration, and the reaction time. The results revealed that 3 g of extracts, 0.005 M AgNO3, and 30 min of incubation time were the ideal conditions to synthesize AgNPs-Cur. The characterization was assessed by UV-Visible spectroscopy, FTIR, and TEM. UV-Vis spectra showed a surface plasmon resonance (SPR) peak at 428 nm with the stability after 5 months of storage time. FTIR analysis revealed the formation of AgNPs using turmeric extracts and the synthesized AgNPs-Cur had the average size of 22.12 ± 0.60 nm (analyzed by TEM). The well diffusion and disc diffusion method were performed to investigate the antibacterial activity of AgNPs-Cur against Bacillus subtilis, Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa. The results concluded that AgNPs-Cur exhibited better bacterial growth inhibitory activities with well diffusion method than disc diffusion method.

Bioinspired Synthesis of Gold Nanoparticles for Enhanced Anti-Cancer Activity and Cell Viability Studies

Gold nanoparticles, or AuNPs, have garnered significant attention in biomedical research, especially in cancer therapy, due to their unique physicochemical properties. This work discusses the bioinspired production of gold nanoparticles (AuNPs) using plant extracts as reducing and stabilizing agents. This research conducted the synthesis. Transmission electron microscopy (TEM), ultraviolet-visible spectroscopy (UV-Vis), dynamic light scattering (DLS), and Fourier transform infrared spectroscopy (FTIR) were used to analyze the synthesized nanoparticles. These approaches were used to characterize the nanoparticles’ dimensions, morphology, stability, and functional groups. At a wavelength of 532 nm, the nanoparticles, averaging 18 ± 3 nm in size, exhibited a pronounced surface plasmon resonance (SPR) peak, indicating the efficacy of the manufacturing method. Cell viability assessments performed using HeLa (a cervical cancer cell type), MCF-7 (a breast cancer cell model), and WI-38 (a healthy fibroblast cell model) demonstrated a concentration-dependent reduction in cancer cell viability, with little impact on healthy cells. At a concentration of 100 µg/mL of AuNPs, the viability of HeLa and MCF-7 cells decreased to 35.2% and 41.7%, respectively. The viability of WI-38 cells was maintained at 83.4%. The analysis of apoptosis revealed that the AuNPs induced apoptosis in cancer cells. The early and late apoptosis rates in HeLa cells were 35.4% and 45.8%, respectively, but in MCF-7 cells, they were 32.5% and 42.1%. The therapeutic efficacy of the nanoparticles was significantly enhanced by the bioactive compounds isolated from the plant. The eco-friendly synthesis method used in this study not only provides a sustainable means for nanoparticle production but also enhances the potential for their application in anti-cancer therapies. The therapeutic applications of these bioinspired AuNPs will be further explored via in vivo tests, which will be the emphasis of next research.

Green mediated synthesis of silver nanoparticle using Euphorbia Maculate leaf extract and their catalytic reduction and antibacterial properties

Conventional methods for silver nanoparticles (AgNPs) synthesis often rely on harsh chemicals and hazardous reducing agents, raising concerns about environmental pollution and toxicity. This study reports the green synthesis of AgNPs using Euphorbia maculata (EM) leaf extract as a reducing and capping agent. This one-pot synthesis, conducted at room temperature, offers a simple, rapid, and cost-effective alternative to conventional methods. Additionally, it eliminates the need for external stabilizers or reducing agents, making it environmentally friendly and sustainable. Surface plasmon resonance (SPR) peak at 430 nm in the UV–vis spectrum indicated the successful synthesis of AgNPs. High-resolution transmission electron microscopy (HR-TEM) analysis revealed spherical AgNPs with an average diameter of approximately 10.85 nm. X-ray diffraction (XRD) pattern confirmed the AgNPs to be face-centered cubic (FCC) crystalline. Fourier-transform infrared spectroscopy (FTIR) analysis identified the presence of phenolic compounds in the EM extract, which are responsible for the reduction of silver ions and act as natural stabilizers. Additionally, a pH optimization study revealed that a pH of 9 is optimal for producing AgNPs. AgNPs-EM exhibited potent antibacterial activity against both Gram-positive and Gram-negative bacteria, with a stronger effect observed against E. coli. Additionally, they displayed excellent catalytic activity for the reduction of o-nitroaniline.

Green synthesis of silver nanoparticles using Justicia adhatoda leaves extract and its anticancer effect on human lung carcinoma via induced apoptosis mechanism

In this study, Justicia adhatoda leaves extract was used to synthesize silver nanoparticles (AgNPs) and assess its anticancer attributes against human lung carcinoma (A549) cell line via induction of apoptosis mechanism. Initially, the biosynthesis of AgNPs was evident by observing the appearance of dark brown colour solution. UV–Vis spectrum showed characteristic surface plasmon resonance peak at 420 nm. FT-IR spectroscopy demonstrated the presence of distinct functional groups in both the extract and AgNPs. The peaks in XRD pattern corresponded to 101, 111, 200, and 220 crystal planes, thereby representing face-centred cubic silver. The EDX analysis confirmed the reduction of silver ions. The HR-SEM revealed spherical-shaped nanoparticles with an average size of 8–13 nm. In vitro cytotoxicity of extract and AgNPs was determined against A549 cell lines using MTT assay. The AgNPs revealed higher cytotoxity (59.25 ± 1.3–5.55 ± 1.3 %) than the extract (81.48 ± 1.3–16.66 ± 1.6 %) with reduced viabilities of cells at different concentrations. The IC50 values of the extract and AgNPs were calculated as 95.36 and 15.1 µg/mL, respectively. Apoptosis of AgNPs was analyzed using varied techniques as per the standard protocols. Acridine orange staining showed reduced green fluorescence of A549 cells due to the action of AgNPs. DNA fragmentation assay revealed the breakage of DNA double strands of cells and yielded laddered pattern. Flow cytometry analysis depicted increment in the cells count in S phase and concomitant decrement in Go/G1 phase. Quantitative real-time PCR demonstrated the upregulation and downregulation of Bax and Bcl-2 genes, respectively. Additionally, the exposure of A549 cells with AgNPs induced cytochrome C production from depolarized mitochondrial membrane into cytosol, which further upregulated caspase-9 and caspase-3 genes. In conclusion, J. adhatoda leaves-mediated AgNPs induced the apoptosis mechanism in A549 lung adenocarcinoma cells and indicated its paramount role as an effectual anticancer agent in future nanomedicine.

Green synthetic photo-irradiated chitin-silver nanoparticles for antimicrobial applications

The primary purpose of this study was to synthesize silver nanoparticles (AgNPs) utilizing chitin extracted from shrimp shell waste by simple photo-irradiation in a single-pot biosynthesis without adding any toxic chemical substances. Glucose molecules in the chitin extract act as the reducing agent, while amino acids in chitin behave like proteins and are responsible for the production of AgNPs by acting as the particle-stabilizing agent. The synthesized chitin-AgNPs were thoroughly investigated using transmission electron microscopy (TEM), Fourier-transform infrared analysis, and ultraviolet-visible absorption spectroscopy. UV-visible spectroscopy revealed a surface plasmon resonance peak at 470 nm, confirming the formation of chitin-AgNPs. FTIR data confirmed the association between chitin and AgNPs. TEM studies showed that the synthesized chitin-AgNPs have a spherical shape with particle sizes ranging from 10 to 30 nm. The prepared chitin-AgNPs exhibited intense antibacterial activity against the Gram-positive Bacillus subtilis, Staphylococcus aureus, Gram-negative Pseudomonas aeruginosa, and Escherichia coli, as well as antifungal efficacy against Aspergillus niger. Reactive oxygen species and live and dead cell assays were performed to examine the chitin- AgNPs and the results were further found to be interesting and positive. The assays revealed that the prepared chitin- AgNPs exhibited significant antimicrobial potential against B. subtilis and A. niger, with a zone of inhibition measuring approximately 6.2 mm and 30 mm, respectively. The effects of the chitin-AgNPs were compared to those of commercial agents, such as ciprofloxacin (6.0 mm) and fluconazole (25 mm). Consequently, the chitin-AgNPs developed through a greener approach show promising potential as sustainable materials for antibacterial and antifungal activities.

Green synthesis of non-toxic silver nanoparticles using Salvia tebesana Bunge extract: Optimization, cytotoxicity, and antibacterial activities

The remarkable antibacterial activity and potential biomedical applications of silver nanoparticles (AgNPs) synthesized through eco-friendly approaches have garnered significant attention in recent years. This research aimed to introduce a green synthesis method for AgNPs using Salvia tebesana (S. tebesana) Bunge extract and to investigate their properties, antibacterial activities, and cytotoxicity effects. The fabricated AgNPs were analyzed with various analyses, including UV–Vis, DLS, XRD, FT-IR, and TEM analysis. The broth microdilution assay was applied to measure the Minimum Inhibitory Concentrations (MIC) of chemical AgNPs, biosynthesized AgNPs, and S. tebesana Bunge leaves extract alone against selected standard bacteria strains. The biosynthesized AgNPs displayed a surface plasmon resonance peak at approximately 415 nm, and the AgNPs synthesized using S. tebesana Bunge extract had a spherical configuration with an average size in the range of 10–15 nm. Biosynthesized nanoparticles showed a noteworthy antibacterial activity compared to chemical nanoparticles, particularly against P. aeruginosa, with the highest antibacterial activity reported at a MIC value of 39.06 μg/mL. AgNPs synthesized using S. tebesana Bunge extract demonstrated a significant decrease in fibroblast cell viability, but only when the concentration reached 2 mg/mL. The findings demonstrate that S. tebesana Bunge leaves extract enhances the antibacterial properties of AgNPs, and also represents an appropriate and biocompatible option for the synthesis of these nanoparticles. Our research highlights the potential of employing bio-safe and eco-friendly AgNPs synthesized in the presence of S. tebesana Bunge extract, which possess remarkable antibacterial properties, for various biomedical applications.