Biosynthesis, characterization and study of the application of silver nanoparticle for 4-nitrophenol reduction, and antimicrobial activities

Silver nanoparticles (AgNPs) were synthesized from Vigna unguiculata (L) Walp extracted leaves, and characterized. The UV-Visible spectrum showed a peak between 411 and 415 nm at the Plasmon absorbance of the AgNPs. TEM showed that the size of AgNPs ranged from 5 to 13 nm. It was spherical with an average size of 11.08 nm. The size of AgNPs was 7 ± 6 nm and disperse in water. The AgNPs effectively reduced 4-Nitrophenol (4-NP) to 4-aminophenol (4-AP) in the presence of NaBH4. The AgNPs exhibited a strong antioxidant and antibacterial activity against Gram-negative bacteria: Escherichia coli (E. coli) and Klebsiella pneumonia and Gram-positive: Bacillus pumilus and Staphylococcus aureus. The average zones of inhibition of AgNPs were: 29 mm for Staphylococcus aureus, 23 mm for Bacillus pumilus, 17 mm for Klebsiella pneumonia and 15 mm for Escherichia coli (E. coli). Thus, AgNPs has exhibted good antibacterial activity compared to antibiotics drug and 4-NP reduction.

Phytonano silver for cosmetic formulation- synthesis, characterization, and assessment of antimicrobial and antityrosinase potential

Novel formulations of silver nanoparticles remain exciting if it is applicable for cosmetic purposes. This study proposes a value-added brand-new nanomaterial for improving skin complexion by inhibiting melanin development. This work aims to develop cost effective, efficient, natural silver nanoparticles phytomediated by aqueous extract of leaf sheath scales of Cocos nucifera (Cn-AgNPs) having potential as tyrosinase inhibitors hindering melanin synthesis. The formation of Cn-AgNPs was assessed spectrophotometrically and confirmed by the sharp SPR spectrum at 425 nm. The chemical composition profiling was characterized by X-ray diffraction (XRD) and Fourier Transform Infrared (FTIR) spectroscopy. The morphology was confirmed by Field Emission Scanning Electron Microscopy (FESEM) and the thermal stability was assessed by Thermogravimetric analysis (TGA). Pharmacological application studies supported the materialization of Cn-AgNPs with significant antityrosinase potential and considerably improved antibacterial and antioxidant properties. Cn-AgNPs showed potential antibacterial effects against gram-positive and negative strains, including prominent infectious agents of the skin. Antioxidant capacity was confirmed with an IC50 of 57.8 μg/mL by DPPH radical scavenging assay. Furthermore, in vitro melanin content determination was performed using SK-MEL cells. Cell line studies proved that Cn-AgNPs decrease the melanin content of cells. The IC50 value obtained was 84.82 μg/mL. Hence Cn-AgNPs is proposed to be acting as a whitening agent through lessening cellular melanin content and as a significant inhibitor of tyrosinase activity. The antioxidant properties and antibacterial effects can contribute to skin rejuvenation and can prevent skin infections as well. This evidence proposes the development of a new nanostructured pharmaceutical and cosmetic formulation from Cocos nucifera leaf sheath scales.

Improving the sensing sensitivity of silver nanoparticle-based colorimetric biosensors from the point of salt

The sensing sensitivity was improved for silver nanoparticles (AgNPs)-based colorimetric biosensors by using the most suitable salt to induce AgNPs aggregation. As for the salt composed of low-affinity anion and monovalent cation, the cation-dependent charge screening effect was the driving force for AgNPs aggregation. Apart from the charge screening effect, both the bridging of multivalent cation to the surface ligand of AgNP and the interaction between anion and Ag contributed to inducing AgNPs aggregation. Considering the higher aggregation efficiency of AgNPs resulted in a narrower sensing range, salt composed of low-affinity anion and monovalent cation was recommended for AgNPs-based colorimetric analysis, which was confirmed by fourfold higher sensitivity of DNA-21 detection using NaF than NaCl. This work inspires further thinking on improving the sensing performance of metal nanomaterials-based sensors from the point of colloidal surface science.

Using silver nanoparticle-decorated whey protein isolate amyloid fibrils to modify the electrode surface used for electrochemical detection of para-nitrophenol

Due to their organized structures, remarkable stiffness, and nice biocompatibility and biodegradability, amyloid fibrils serve as building blocks for versatile sustainable materials. Silver nanoparticles (AgNPs) are commonly used as the nano-catalysts for various electrochemical reactions. Given their large specific surface area and high surface energy, AgNPs exhibit high aggregation propensity, which hampers their electrocatalytic performance. Food protein wastes have been identified to be associated with climate change and environmental impacts, and a surplus of whey proteins in dairy industries causes high biological and chemical demands, and greenhouse gas emissions. This study is aimed at constructing sustainable electrode surface modifiers using AgNP-deposited whey protein amyloid fibrils (AgNP/WPI-AFs). AgNP/WPI-AFs were synthesized and characterized via spectroscopic techniques, electron microscopy, and X-ray diffraction. Next, the electrocatalytic performance of AgNP/WPI-AF modified electrode was assessed via para-nitrophenol (p-NP) reduction combined with various electrochemical analyses. Moreover, the reaction mechanism of p-NP electrocatalysis on the surface of AgNP/WPI-AF modified electrode was investigated. The detection range, limit of detection, sensitivity, and selectivity of the AgNP/WPI-AF modified electrode were evaluated accordingly. This work not only demonstrates an alternative for whey valorization but also highlights the feasibility of using amyloid-based hybrid materials as the electrode surface modifier for electrochemical sensing purposes.

Biological activity of silver nanoparticles synthesized using viticultural waste

This research paper presents a novel approach to the green synthesis of silver nanoparticles (AgNPs) using viticultural waste, allowing to obtain NP dispersions with distinct properties and morphologies (monodisperse and polydisperse AgNPs, referred to as mAgNPs and pAgNPs) and to compare their biological activities. Our synthesis method utilized the ethanolic extract of Vitis vinifera pruning residues, resulting in the production of mAgNPs and pAgNPs with average sizes of 12 ± 5 nm and 19 ± 14 nm, respectively. Both these AgNPs preparations demonstrated an exceptional stability in terms of size distribution, which was maintained for one year. Antimicrobial testing revealed that both types of AgNPs inhibited either the growth of planktonic cells or the metabolic activity of biofilm sessile cells in Gram-negative bacteria and yeasts. No comparable activity was found towards Gram-positives. Overall, pAgNPs exhibited a higher antimicrobial efficacy compared to their monodisperse counterparts, suggesting that their size and shape may provide a broader spectrum of interactions with target cells. Both AgNP preparations showed no cytotoxicity towards a human keratinocyte cell line. Furthermore, in vivo tests using a silkworm animal model indicated the biocompatibility of the phytosynthesized AgNPs, as they had no adverse effects on insect larvae viability. These findings emphasize the potential of targeted AgNPs synthesized from viticultural waste as environmentally friendly antimicrobial agents with minimal impact on higher organisms.

Alginic acid-functionalized silver nanoparticles: A rapid monitoring tool for detecting the technology-critical element tellurium

The increasing global demand for tellurium, driven by its critical role in alloys, photovoltaic devices, and electronics, has raised concerns about its environmental pollution and neurotoxicity. In response, the potential of alginic acid (AA), a renewable, low-cost, and sustainable biopolymer, was explored for the biosynthesis of ultra-small silver nanoparticles (AgNPs) and their application in the detection of tellurium (Te(IV)). The effect of key synthesis parameters on desired physicochemical properties and yield of AgNPs was established to ensure high specificity and sensitivity towards Te(IV). The purified AgNPs with AA surface ligands were utilized to demonstrate a ratiometric absorbance sensor that exhibits excellent linearity and nanomolar-level affinity. This approach achieved a high correlation coefficient of ∼ 0.982, with a low detection limit of about 22 nM. Further investigations into the effect of pH, ionic strength, and organic molecules were conducted to elucidate detection performance and molecular understanding. The detection mechanism relies on the coordination between Te(IV) ions and the carboxylate groups of AA, which initiates aggregation-induced plasmon coupling in adjacent AgNPs. The capability of this analytical method to monitor Te(IV) in real-world water samples features its rapidity, user-friendliness, and suitability for point-of-care monitoring, making it a promising alternative to more complex techniques.

Coaxial nanofibers encapsulated with Ampelopsis brevipedunculata extract and green synthesized AgNPs for wound repair

Silver nanoparticles (AgNPs) synthesized from Aloe vera extract exhibited a pronounced antibacterial effect, while the Ampelopsis brevipedunculata extract (ABE) showcased a high antioxidant capacity for wound healing. Spherical AgNPs with a particle size of 28.82 nm crystallized in a face-centered-cubic lattice. AgNPs/polyvinyl alcohol (PVA) and ABE/polycaprolactone (PCL) underwent electrospinning to produce coaxial and electrosprayed nanofibers, respectively. The developed coaxial nanofibers demonstrated a strain of 159%, a Young's modulus of elasticity of 7080.14 kPa, a 3.9-fold swelling ratio, a water contact angle of 38.91°, characteristic hydrophilicity, and an adequate water vapor transmission rate of 2272 g/m2/day. ABE exhibited no cytotoxicity to L929 cells and induced a twofold increase in the cell migration rate. Upon applying the developed coaxial nanofiber on an in vivo rat model with a 9 mm wound diameter, the wound rapidly and completely healed within 10 days, with a healing speed 60% greater than that of the control group. Histopathological analysis revealed that the coaxial group did not exhibit inflammation, showed complete epithelization, and featured a well-arranged deposition of collagen on the 10th day.

Insights into the physico-chemical and biological characterization of sodium lignosulfonate - silver nanosystems designed for wound management

Chronic wounds represent one of the complications that might occur from the disruption of wound healing process. Recently, there has been a rise in interest in employing nanotechnology to develop novel strategies for accelerating wound healing. The aim of the present study was to use a green synthesis method to obtain AgNPs/NaLS systems useful for wounds management and perform an in-depth investigation of their behavior during and post-synthesis as well as of their biological properties. The colloids obtained from silver nanoparticles (AgNPs) and commercial sodium lignosulfonate (NaLS) in a single-pot aqueous procedure have been fully characterized by UV-Vis, FT-IR, DLS, TEM, XRD, and XPS to evaluate the synthesis efficiency and to provide new insights in the process of AgNPs formation and NaLS behavior in aqueous solutions. The effects of various concentrations of NaLS (0-16 mg/mL) and AgNO3 (0-20 mM) and of two different temperatures on AgNPs formation have been analyzed. Although the room temperature is feasible for AgNPs synthesis, the short mixing at 70 °C significantly increases the speed of nanoparticle formation and storage stability. In all experimental conditions AgNPs of 20-40 nm in size have been obtained. The antimicrobial activity assessed quantitatively on clinical and reference bacterial strains, both in suspension and biofilm growth state, revealed a broad antimicrobial spectrum, the most intensive inhibitory effect being noticed against Pseudomonas aeruginosa and Escherichia coli strains. The AgNP/NaLS enhanced the NO extracellular release, potentially contributing to the microbicidal and anti-adherence activity by protein oxidation. Both AgNP/NaLS and NaLS were non-hemolytic (hemolytic index<5%, 2.26 ± 0.13% hemolysis) and biocompatible (102.17 ± 3.43 % HaCaT cells viability). The presence of AgNPs increased the antioxidative activity and induced a significant cytotoxicity on non-melanoma skin cancer cells (62.86 ± 8.27% Cal-27 cells viability). Taken together, all these features suggest the multivalent potential of these colloids for the development of novel strategies for wound management, acting by preventing infection-associated complications and supporting the tissue regeneration.

Determination of the Cytotoxicity and Antibiofilm Potential Effect of Equisetum arvense Silver Nanoparticles

This study aimed to synthesize and characterize silver nanoparticles (AgNPs) by green synthesis from Equisetum arvense (Ea) extracts and to investigate their cytotoxicity, antibiofilm activity, and α-glucosidase enzyme inhibition. Diverse characterization techniques were applied to verify the production of nanoparticles. SEM examination confirmed that the size of nanoparticles is in the range of 40-60 nm. Also, interactions between silver and natural compounds of plant extract were confirmed through FT-IR and EDX analyses. It was determined that Equisetum arvense silver nanoparticles had antibiofilm activity against three different clinical strains with high biofilm-forming ability. AgNPs reduced the biofilm-forming capacity of clinical A. baumannii isolate with strong biofilm-forming capacity by approximately twofold, while the capacity of clinical K.pneumonaie and E.coli isolates decreased by 1.5 and 1.2 fold, respectively. The α-glucosidase enzyme inhibition potential of the AgNPs, which is determined as 93.50%, was higher than the plant extract with, and the α- 30.37%. MTT was performed to assess whether incubation of nanoparticles with A549 and ARPE-19 cell lines affected their viability, and a dramatic reduction in cell growth inhibition of both A549 and ARPE-19 cells was observed. It has been shown that A549 cells treated with 200 and 150 µg/mL nanoparticles had less cell proliferation compared to control cells at 24-h and 48-h incubation time. According to these results, Ea-derived AgNPs appear to have potential anticancer activity against A549 cancer cells. Investigating the effects of green synthesis nanoparticles on microbial biofilm and various tumors may be important for developing new therapies. The outcomes of this study have showed that Ea-AgNPsmay have a high potential both in the treatment of pathogenic strains that form biofilms, as well as in anticancer therapy use.

Fabrication of controlled-release silver nanoparticle polylactic acid microneedles with long-lasting antibacterial activity using a micro-molding solvent-casting technique

Most topical drug delivery techniques do not provide therapeutic concentrations for treatment of surgical site and other local infections and, therefore, require some kind of enhancement, such as physical methods like microneedles, the subject of the present investigation. Here, controlled-release long-lasting antibacterial polylactic acid (PLA) microneedles containing 1, 3, and 5% silver nanoparticles (AgNP) were prepared using micro-molding solvent-casting technique. Microneedles were characterized using optical microscopy, SEM, FTIR, XRD, and DSC. Also, mechanical strength, barrier disruption ability, insertion depth, in-vitro release kinetics, antibacterial activity against Staphylococcus aureus and Pseudomonas aeruginosa, and silver permeation through rat skin were studied. Microneedles showed good mechanical strength with no signs of failure at an optimum PLA concentration of 25% (w/v). FTIR revealed no chemical interaction between ingredients, and XRD confirmed presence of AgNP in microneedles. Microneedles penetrated the skin model at depth of up to 1143 μm resulting 5-7 times increase in transepidermal water loss (TEWL). Release studies showed 2.2, 6.8, and 8.1 µg silver release from the whole body (obeying Higuchi's release model) and 0.33, 0.45, and 0.78 µg from the needles alone (obeying Fickian-cylindrical type release) for 1, 3, and 5% AgNP microneedles, respectively. Also, prolonged antibacterial activity (for 34 days) was observed. Skin studies over 72 h indicated that besides needles, silver is also released from the baseplate which had a marginal share in total silver permeation through the skin. In conclusion, a straightforward solvent-casting technique can be used to successfully prepare strong AgNP-containing PLA microneedles capable of long-lasting antibacterial activity.

Investigation of Antibiofilm and Antibacterial Properties of Green Synthesized Silver Nanoparticles from Aqueous Extract of Rumex sp

The decrease in the effectiveness of conventional drugs as a result of the growth of resistance to antibiotics has increased the need for innovative tools to control the infections. At this point, metallic nanoparticles, in particular silver nanoparticles, have appeared as a promising method. In the current study, the extract of Rumex sp. (Labada, dock) leaves was used as a reducing agent for the formation of silver nanoparticles. Unlike similar studies, in this study the synthesis conditions were optimized by changing the extract ratio and silver nitrate concentration. Morphological investigations of synthesized silver nanoparticles showed that spherical homogeneous particles at size under 100 nm had been produced. SEM/EDS and FTIR analyses showed that plant components are involved in the synthesis of nanoparticles. It was also determined that higher extract ratio reduced nanoparticle size. The antimicrobial effects of the synthesized nanoparticles against Gram-positive and Gram-negative bacteria were tested, and it was determined that all nanoparticles exhibited activity against both groups. Rumex sp. silver nanoparticles (NPs) were revealed to exhibit antibiofilm activity against three different isolates with moderate and strong biofilm-forming ability. The NPs reduced the biofilm-forming capacity of Acinetobacter baumannii and Klebsiella pneumonaie by 2.66-fold and 3.25-fold, whereas they decreased the Escherichia coli biofilm-forming capacity by 1.25-fold. The investigation of microbial biofilm could play an important role in developing new strategies for treatment options. Our results suggest that Rumex sp. silver NPs may have a high potential for use in the treatment of pathogenic strains.

Formulation and characterization of polyvinyl alcohol/chitosan composite nanofiber co-loaded with silver nanoparticle & luliconazole encapsulated poly lactic-co-glycolic acid nanoparticle for treatment of diabetic foot ulcer

Chronic wounds are prone to fungal infections, possess a significant challenge, and result in substantial mortality. Diabetic wounds infected with Candida strains are extremely common. It can create biofilm at the wound site, which can lead to antibiotic resistance. As a result, developing innovative dressing materials that combat fungal infections while also providing wound healing is a viable strategy to treat infected wounds and address the issue of antibiotic resistance. Present work proposed anti-infective dressing material for the treatment of fungal strains Candida-infected diabetic foot ulcer (DFU). The nanofiber was fabricated using polyvinyl Alcohol/chitosan as hydrogel base and co-loaded with silver nanoparticles (AgNP) and luliconazole-nanoparticles (LZNP) nanoparticles, prepared using PLGA. Fabricated nanofibers had pH close to target area and exhibited hydrophilic surface suitable for adhesion to wound area. The nanofibers showed strong antifungal and antibiofilm properties against different strains of Candida; mainly C. albicans, C. auris, C. krusei, C. parapsilosis and C. tropicalis. Nanofibers exhibited excellent water retention potential and water vapour transmission rate. The nanofibers had sufficient payload capacity towards AgNP and LZNP, and provided controlled release of payload, which was also confirmed by in-vivo imaging. In-vitro studies confirmed the biocompatibility and enhanced proliferation of Human keratinocytes cells (HaCaT). In-vivo studies showed accelerated wound closure by providing ant-infective action, supporting cellular proliferation and improving blood flow, all collectively contributing in expedited wound healing.

Antibacterial, antibiofilm and larvicidal activity of silver nanoparticles synthesized from spider silk protein

Green synthesis of silver nanoparticles has gained attention due to its simple process of synthesis and varied applications. Scientists have tried its synthesis from a wide range of materials, but there is lack of reports that can use the metabolites of insects. Here in this study, we have used the spider silk protein which is considered as complete waste collected from household and field sources and processed to synthesize silver nanoparticles which were subsequently analyzed using different analytical tools like SEM, TEM, FTIR, and XRD. The spider silk protein-mediated synthesized nanoparticle (SP-AgNPs) showed a sharp peak at 420 nm when analyzed spectrophotometrically giving an indication of successful synthesis of AgNP. The synthesized nanoparticle ranges from 10 to 40 nm and were of varied shapes. The synthesized SP-AgNPs showed remarkable antibacterial activity. The MIC values against B. subtilis and E. coli were recorded 45 and 40 μg/mL respectively. Further to know the mechanisms of antibacterial activity protein leakage and conductivity measurement were conducted. The synthesized nanoparticle also showed excellent antibiofilm activity with inhibition percentages of 74 % and 68 % for E. coli and B. subtilis respectively at MIC concentration of the treatment. Finally, the synthesized nanoparticles was applied as mosquito larvicidal agent against Culex sp. and the difference between LC50 and LD90 value was recorded as statistically significant (p < 0.0267) during 24 h of incubation. Therefore, it can be said that spider-web could be an excellent biological reducing and capping agent for heavy metal nanoparticle synthesis that can minimize the ailments caused by mosquitoes and pathogenic microorganisms.

"Antimicrobial properties of tissue conditioner modified with chitosan and green-synthesized silver nanoparticles: a promising approach for preventing denture stomatitis"

BACKGROUND

Chitosan is known to inhibit the growth of many bacteria and fungi. Tissue conditioners are commonly used to prevent bone destruction under dentures. However, over time, these materials can become a suitable substrate for microbial growth. One approach to improving dental materials is the use of nanoparticles. This study examined the antifungal properties of chitosan and green technique-synthesized silver nanoparticles in combination with tissue conditioners.

METHODS

Tissue conditioner materials were mixed with chitosan and silver nanoparticles at concentrations of 0.097%, 0.19%, and 0.37%, along with 1.25 ppm Nystatin, and their antimicrobial properties against Candida albicans were investigated. The growth rate was measured after 24 h of incubation at 37 °C. Non-parametric tests, such as the Kruskal-Wallis H test and Mann-Whitney U test with Bonferroni correction, were used for data analysis after verifying that the groups did not have a normal distribution.

RESULTS

Compared with the control and Nystatin groups, the Chitosan-silver groups showed a significant decrease in the number of CFUs of Candida albicans.

CONCLUSIONS

The combination of chitosan and silver nanoparticles with tissue conditioner materials is a promising alternative for preventing and treating denture stomatitis. These findings suggest that using very small amounts of nanoparticles in dental materials could effectively prevent microbial growth, which could improve the longevity and efficacy of dental prosthetics and materials.

Hierarchical plant extracts in silver nanoparticles preparation: Minuscular survey to achieve enhanced bioactivities

Extracts obtained from M. longifolia (Lamiaceae) and R. ellipticus (Rosaceae) were selected to utilize in the reduction and stabilization of silver nanoparticles (AgNPs) for achieving remarkable bioactivities. In brief, the cytotoxic potential of the as synthesize AgNPs was high at higher concentrations. In DPPH assay, maximum antioxidant potential was shown by AgNPs synthesized from M. longifolia. Meanwhile, Methanolic extracts exhibited more antioxidant potential than chloroform based extracts. Further, brine shrimp lethality assay was carried out to achieve 34.6 μg/mL & 25.65 μg/mL LD50 values against the NPs prepared from M. and R., respectively. In addition, antioxidant activities were carried by ABTS Radical cation assay where 38.6 μg/mL and 47 μg/mL IC50 values were obtained for the NPs obtained from M. longifolia and R. ellipticus, respectively. Reducing power assay (0.370-0.15 and 0.37-0.26 mean absorbance) and DPPH (% scavenging: 88.91-46.48 and 88.91-44.78) percentages were recorded for M. and R. synthesized AgNPs, respectively. In brief, M. longifolia functionalized particles performed better in comparison to R. ellipticus treated particles. In addition, the nano assembly dispersed in polar solvent demonstrated better results in comparison to non-polar solvents. In conclusion, the as synthesized AgNPs were better in bioactivities than crude extracts of the selected plants. In future, this work could be extended to isolating active components for the nanofabrication of biologically intelligent nanoparticles for pharmacological interest. In the proposed investigation, the purified bioactivities fractions would be highlighted for further consideration in various medical treatments.

On-site quantitation of xanthine in fish and serum using a smartphone-based spectrophotometer integrated with a dual-readout nanosensing assay

Rapid and quantitative biochemical analysis at points-of-need is imperative for food safety inspection. This work reports on: 1) a stand-alone smartphone-based "two-in-one" spectrophotometer (the SAFS) installed with a self-developed application (the SAFS-App) which can precisely collect both absorption spectra and fluorescence spectra in a reproducible manner within 5 s; and 2) a straightforward protocol for xanthine detection using fluorescent carbon nanodots and silver nanoparticles. The assay performed with the SAFS demonstrates high specificity towards xanthine, and a linear range of 1-60 μM with LODs of 0.38 and 0.58 μM for colorimetric and fluorometric readouts, respectively. The reliability and robustness of the SAFS are validated by on-site quantitation of xanthine in fish and serum samples, with comparable accuracy to HPLC method. More importantly, the SAFS presents itself as an appealing device which is accessible to everyone through the Internet of Things and can be tailored for diverse point-of-care testing applications.

Handheld UV spectrophotometer device for detection of methamphetamine hydrochloride based on supramolecular sensing platform

The realization of drug detection in drug-using crime sites can provide law enforcement officials with direct evidence. This research has developed and demonstrated an easy-to-use handheld sensor that can quickly detect methamphetamine (MA) in the field. The core of the handheld UV spectrophotometer device (HUVSD) is the STM32F103 series of single-chip micro-controller, which has a 32-bit microcontroller and two embedded 12-bit high-precision analog-to-digital converter (ADC) modules. Through Bluetooth-wireless transmission protocol, the spectral information can be displayed in the cell phone's app, and it is possible to visually determine whether the test sample contains methamphetamine hydrochloride substances based on the characteristic peak at 410 nm. The readily available and inexpensive inducible compound 3A and the phosphate pillar[5]arene@silver nanoparticle (PP5@AgNPs) colloidal solution were used as the reactants. The PP5@AgNPs colloidal solution and 3A were mixed and reacted at room temperature, and the color changed to gray-black. The color change was caused by the aggregation of AgNPs induced by the molecular recognition between the induction compound 3A and PP5 on the AgNPs surface. After continuing to add the drug MA, the color of the colloidal solution turned yellow again. This is due to the occurrence of competitive molecular recognition, and the interaction between PP5 and 3A/MA was investigated by molecular docking simulations. The HUVSD has high sensitivity, simple equipment, time-saving, color change visualization and suitable for on-site deployment. It only needs a Pasteur pipette, which has great potential to realize rapid on-site detection.

Concentration analysis of metal-labeled nanoplastics in different water samples using electrochemistry

Despite the threats posed by nanoplastics to the environment and human health, little was known about the occurrence, formation, migration, and environmental impacts of nanoplastics due to the lack of quantitative and sensitive detection techniques. In this work, an electrochemical strategy for the detection of nanoplastics based on Ag labeling was proposed. Positively charged silver ions were attached to negatively charged polystyrene nanoplastics (PSNPs), and then the silver ions on the surface of PSNPs were reduced to Ag by sodium borohydride. Subsequently, the concentration of PSNPs was determined by identifying the signal of Ag by differential pulse voltammetry. The method showed different sensitivity for PSNPs of different sizes (100, 367, 500 nm). For tap water samples, the reason for the change in Ag electrochemical signal was discussed. The sensitivity of the method to PSNPs in tap water was investigated. The feasibility of the method for environmental water samples was verified using spiked lake water and spiked seawater, and satisfactory recoveries (93-112 %) were obtained for PSNPs of different sizes and concentrations. This study provided a sensitive, low-cost, and simple method without complex instrumentation, which was important for the determination of PSNPs in environmental water samples.

Biocompatible and antibacterial poly(lactic acid)/cellulose nanofiber‑silver nanoparticle biocomposites prepared via Pickering emulsion method

Developing biocompatible and antibacterial materials with biodegradable polymers is an ideal strategy to improve public health problems and plastic pollution simultaneously. In the present study, novel biocompatible and antibacterial poly (L-lactic acid) (PLLA, coded as P)/TEMPO-oxidized cellulose nanofiber (TOCNF, coded as T)‑silver nanoparticle (AgNP, coded as A) films were first developed. The core/shell PT Pickering emulsion was prepared by sonication treatment. The TOCNF shells with -COO-Na+ groups (∼1.5 mmol/g cellulose) were used as the support to in situ synthesize and immobilize AgNPs on the PT emulsion droplets. Silver nitrate (AgNO3) (1.5, 3.0, 4.5, and 6.0 mmol/g cellulose) was added to the PT emulsions. Then, ion-exchange reaction and hydrothermal reduction were conducted to form PTA (PTA1-PTA4) emulsions. After centrifugation to remove the excess Ag+, filtration, oven-drying, and hot-pressing, the PTA composite films were successfully prepared. The PTA3 film contained AgNPs 12.4 ± 2.8 nm in diameter and exhibited the highest antibacterial activities against the E. coli (85.2%) and S. aureus (80.1%) at 37 °C, where the initial bacterial suspension concentrations were approximately 2 × 108 CFU mL-1. Therefore, the biocompatible and antibacterial PTA3 film is a promising candidate for biomedical applications, in particular as an antibacterial bioactive packaging material.

SERS combined with the difference in bacterial extracellular electron transfer ability to distinguish Shewanella

Shewanella plays an important role in geochemical cycle, biological corrosion, bioremediation and bioenergy. The development of methods for identifying Shewanella can provide technical support for its rapid screening, in-depth research into its extracellular respiratory mechanism and its application in ecological environment remediation. As a tool for microbial classification, identification and detection, Surface-enhanced Raman scattering (SERS) has high feasibility and application potential. In this work, bio-synthesized silver nanoparticles (AgNPs) were used as SERS substrates to effectively distinguish different types of Shewanella bacteria based on the difference in bacterial extracellular electron transfer (EET) ability. AgNPs were combined with the analyzed bacteria to prepare "Bacteria-AgNPs" SERS samples, which can strongly enhance the Raman signal of the target bacteria and reliably obtain spatial information of different molecular functional groups of each bacteria. Our developed approach can effectively distinguish between non-metal reducing and metal-reducing bacteria, and can further distinguish the three subspecies of Shewanella (Shewanella oneidensis MR-1, Shewanella decolorationis S12, and Shewanella putrefaciens SP200) at the genus and species level. The Raman signal enhancement is presumably caused by the excitation of local surface plasma (LSP) and the enhancement of surrounding electric field. Therefore, our developed method can achieve interspecific and intraspecies discrimination of bacteria. The proposed method can be extended to distinguish other metal-reducing bacteria, and the novel SERS active substrates can be developed for practical applications.

Regulating Enzyme Catalysis by Tailored Silver Nanocrystals Fabricated with Holigarna arnottiana-Synthesis, Characterization, and Performance Optimization

Modification of catalytic expression of enzymes and regulating their in vivo activity are the goals of novel treatment strategies. A green synthetic nanostructured silver with potent trypsin inhibitory properties has not yet been developed, despite the fact that silver nanoparticles possess unique properties that allow them to efficiently block enzymes. The present study demonstrates for the first time a facile, safe, economic, and eco-friendly synthetic route for silver nanoparticles using an aqueous extract of Holigarna arnottiana bark engineered to interact with trypsin and hinder its activity effectively. The studies carried out to examine the interaction between these biofabricated AgNPs (HaAgNPs) and trypsin by UV-visible spectrophotometry and FTIR spectroscopy suggest that the formation of trypsin-HaAgNP complex is responsible for diminishing the catalytic efficiency of trypsin. In vivo studies on Aedes aegypti larval serum support these instrumental results of HaAgNP-induced trypsin inhibition and proves its application as a biopesticide. It is noteworthy that the bioengineered HaAgNPs were also found to have good inhibition potential against pepsin and urease as well. A variety of methods have been employed to characterize the synthesized biocompatible HaAgNPs and it possesses a characteristic absorption maximum of 420 nm. Their shelf life of above 7 years is noticeable, since none of the reported green synthesized AgNPs possess a shelf life of more than 1 year. Altogether, this work demonstrates that biofabricated HaAgNPs are multifunctional and cost-resilient biological tools that can be used as enzyme regulators possessing antioxidant, antimicrobial, and insecticidal features.

Direct sunlight induced room temperature synthesis of anticancer and catalytic silver nanoparticles by shrimp shell waste derived chitosan

The use of marine waste derived chitosan (CS) for the synthesis of nanomaterials is considered as one of the effective routes for bio-waste management and recovering functional products. Herein, CS capped silver nanoparticles (Ag NPs-CS) with potential anticancer and dye pollutants adoption properties have been synthesized photochemically under direct sunlight. To obtain, CS, shrimp shell waste was subjected to a serious of standard demineralization, deproteinization and deacetylation processes. The electronic absorption peak (400 nm) denoting surface plasmonic resonance of Ag NPs and infrared peaks relevant to CS (3364 cm-1 of OH/NH2, 2932 cm-1 of CH, and 1647 cm-1 of -CO) exhibited peaks confirmed the formation of CS-Ag NPs. Ag NPs-CS exhibited anticancer activity against Human lung adenocarcinoma cell lines (A549), the maximum cell death noticed at the concentration of 20 μg/mL and 70 μg/mL was 20 and 52 %, respectively. An aqueous Ag NPs-CS (100 μg/mL) was degraded ≥95 % of mixed dye target solution (25 mg/mL) containing equal volume of cationic dye (Methylene blue and Rhodamine B) and anionic dye (methyl orange). Therefore, these findings suggest that the shrimp shell waste derived CS can be used for the synthesis of CS-Ag NPs with potential biomedical and environmental applications.

Multifunctional nanocoating for enhanced titanium implant osseointegration

Preventing bacterial infection and promoting osseointegration are essential for the long-term success of titanium (Ti) implants. In this study, we developed a multifunctional nanocoating on Ti mini-implants to simultaneously address these challenges. The nanocoating consists of self-assembled antimicrobial peptides GL13K and silver nanoparticles, referred to as Ag-GL. Our results showed that the Ag-GL coating did not alter the surface morphology of the mini-implants. Ag-GL coated mini-implants demonstrated a two orders of magnitude reduction in colony-forming unit (CFU) values compared to the noncoated eTi group, resulting in minimal inflammation and no apparent bone destruction in a bacterial infection in vivo model. When evaluating osseointegration properties, micro-CT analysis, histomorphometric analysis, and pull-out tests revealed that the Ag-GL coating significantly enhanced osseointegration and promoted new bone formation in vivo.

Assessment of Toxicity of Green Synthesized Silver Nanoparticle-coated Titanium Mini-implants with Uncoated Mini-implants: Comparison in an Animal Model Study

AIM

To assess the potential for systemic toxicity when silver nanoparticle-coated mini-implants were implanted in Wistar albino rats conducted as a comparative study in the animal model by assessing the blood biochemistry, liver and kidney function, and histology of the implanted site.

MATERIALS AND METHODS

The surface of the mini-implant was coated with a green-mediated silver nanoparticle. Uncoated mini-implants were placed in two groups of eight Wistar albino rats, and silver nanoparticle-coated mini-implants were placed in another eight rats. The bone's general conditions, blood biochemistry assessing for ALT, AST, GPT, GOT, and histological sections using H and E stain and Masson's Trichrome stain were examined at 7, 14, and 28-day intervals.

RESULTS

The creatinine, urea, ALP, and ALT showed no signs of systemic toxicity during the 28-day follow-up period in the Wistar rats both in the test and control groups. The histological evaluation, which was conducted using HE and MTS stain, revealed osteogenesis and adequate healing of the insertion site in the group where coated mini-implant was placed. The bone sample revealed no abnormalities in the control group with uncoated mini-implants.

CONCLUSION

Green synthesized silver nanoparticle-coated mini-implant does not cause systemic toxicity as indicated by no abnormalities in the levels of creatinine, urea, ALT, ALP, GPT, and GOT. The bone histology indicates that the coated mini-implants placed in animal bone healed with adequate osteogenesis.

CLINICAL SIGNIFICANCE

Silver nanoparticles have potential for antimicrobial activity. Mini-implants placed as temporary anchorage devices in orthodontics often fail due to inflammation and plaque. Silver nanoparticle-coated mini-implants would reduce the risk of mini-implant failure as it would have antimicrobial potential and eliminate this cause for failure of mini-implants. How to cite this article: Sreenivasagan S, Subramanian AK, Mohanraj KG, et al. Assessment of Toxicity of Green Synthesized Silver Nanoparticle-coated Titanium Mini-implants with Uncoated Mini-implants: Comparison in an Animal Model Study. J Contemp Dent Pract 2023;24(12):944-950.

Green Synthesis and Characterization of Silver Nanoparticles from Eclipta alba and Its Activity Against Triple-Negative Breast Cancer Cell Line (MDA-MB-231)

Triple-negative breast cancer (TNBC) doesn't have well-defined molecular targets making it unable to treat with chemotherapy also have faster metastatic rate and worse survival rate. In the current study we aim to target TNBC through eco-friendly green synthesized silver nanoparticles having anti-cancer phytoconstituents from the traditional anti-cancer medicinal plant Eclipta alba. Green synthesized silver nanoparticles (AgNPs) are agglomerates of spherical shaped 40-60 nm sized showing characteristic light absorption at 437 nm, banding pattern at 1479, 1285, 1036, and 471 showing and further X-ray diffraction pattern confirm face-centered cubic crystal silver structure exist in the green synthesized silver nanoparticle preparation. Further in vitro anti-oxidant analysis results revealed that green synthesized AgNPs showed 2.6-fold higher anti-oxidant potential (IC50 15.70 g/ml) than that of aqueous plant leaf extract (IC50 39.80 g/ml). In MTT cytotoxicity analysis Eclipta alba plant extract and AgNPs both display dose-dependent cytotoxicity against triple-negative breast cancer cells (MDA-MB-231), although their IC50 values differ substantially, at 105.80 µg/ml and 77.20 g/ml, respectively. Finally, AgNPs from Eclipta alba tested for anti-leishmanial activity and it showed 91.36 ± 1.05 for promastigotes and 76.62 ± 0.95 for amastigotes at the highest dose of 400 g/ml. Altogether present data showed that Eclipta alba leaf extract actively bonded with silver nanoparticles suppresses the MDA-MB-231 cells growth through high antioxidant characters and anti-leishmanial activity. From together we confirm that Eclipta alba was recommended to a future therapeutic drug and agent to control breast cancer in the clinical level.

Mycosynthesis of silver nanoparticles using marine fungi and their antimicrobial activity against pathogenic microorganisms

OBJECTIVES

At the present time, there is a persistent need to get rid of environmental contaminants by eco-friendly, sustainable, and economical technologies. Uncontrolled disposal practices of domestic and industrial solid and liquid wastes led to water pollution which has negative impacts on public health, environment, and socio-economic development. Several water-borne diseases are spreading man to man by microorganisms such as pathogenic bacteria. For the protection of water bodies, all wastewater from various sources should be managed and remediated properly. Myco-remediation is a form of bioremediation in which fungi are used to get rid of contaminants. Fungi are attractive agents for the biosynthesis of nanoparticles especially silver nanoparticles (AgNPs) which are considered one of the most widely utilized nanoparticles because of their unique characteristics such as antibacterial, antiviral, antifungal, and anti-inflammatory properties.

METHODS

This study uses silver nitrate and supernatants of four marine fungi; Penicillium simplicissimum, Aspergillus terreus, Aspergillus japonicus, and Aspergillus oryzae for extracellular biosynthesis of silver nanoparticles and to evaluate its activity against different pathogenic microorganisms. These nanoparticles may subsequently be applied for the treatment or nano-bioremediation of microbial contaminants in water bodies and improve water quality.

RESULTS

Silver nanoparticles were synthesized and the results revealed that spherical and well-dispersed nanoparticles of different sizes were formed with sizes ranging between 3.8 and 23 nm. Characterization results approved the existence of stable nanocrystalline elemental silver. Antibacterial activity results revealed that AgNPs can be used as a powerful antimicrobial agent for several pathogenic bacteria, yeast, and fungi. Among the biosynthesized NPs mediated by the four marine fungi, AgNPs mediated by A. japonicus (5 mM) had the highest antibacterial activity, while AgNPs mediated by Penicillium simplicissmum (8 mM) had the highest antifungal activity.

CONCLUSION

Marine fungi can biosynthesize stable AgNPs that exhibit potent antimicrobial activity against a variety of pathogens.

Silver Nanoparticles Prepared Using Magnolia officinalis Are an Effective Antimicrobial Agent on Candida albicans, Escherichia coli, and Staphylococcus aureus

Silver nanoparticles (AgNPs) prepared by plants are simple, eco-friendly, and economical. In this study, Magnolia officinalis (MO) extract was applied to synthesize MO@AgNPs. Ultraviolet-visible (UV-vis) spectrum analysis indicated a peak at 440 nm. Most of the particles were spherical with sizes from 1 to approximately 60 nm based on transmission electron microscopy (TEM). X-ray diffraction (XRD) patterns showed a face-centered cubic crystal structure. The zeta value of MO@AgNPs was - 36.5 ± 0.6 mV, which was stable at 25 °C and 4 °C. Growth kinetic studies and the Kirby-Bauer diffusion method showed significant inhibitory activity on Candida albicans (ATCC 10231), Escherichia coli (ATCC BAA-2340), and Staphylococcus aureus (ATCC 25923); the minimum inhibitory concentrations (MIC) were 3, 9, and 9 μg/mL, and corresponding minimum bactericidal concentrations (MBC) were 5, 11, and 9 μg/mL, respectively. MO@AgNPs exhibited better antifungal activity compared to AgNPs prepared using sodium citrate. Further research revealed that MO@AgNPs increased the permeability of bacterial cell membranes. Moreover, the effect of MO@AgNPs on Candida albicans was significantly enhanced by blocking autophagy. The reactive oxygen species (ROS) induced by MO@AgNPs in Candida albicans was limited and may be related to its good antioxidant activity. Finally, MO@AgNPs have no significant cytotoxicity to the human liver LO2 cell line under 20 μg/mL.

Toxicity assessment of poultry-waste biosynthesized nanosilver in Anabas testudineus (Bloch, 1792) for responsible and sustainable aquaculture development-A multi-biomarker approach

The current study investigates the potential utilization of poultry intestines for the synthesis of stable silver nanoparticles (AgNPs) and their impact on fish physiology. The AgNPs were synthesized and characterized using various analytical techniques. The toxicity of AgNPs on Anabas testudineus was evaluated, determining a 96-h LC50 value of 25.46 mg l-1. Subsequently, fish were exposed to concentrations corresponding to 1/10th, 1/25th, 1/50th, and 1/100th of the estimated LC50 for a duration of 60 days in a sub-acute study. A comprehensive range of biomarkers, including haematological, serum, oxidative stress, and metabolizing markers, were analyzed to assess the physiological responses of the fish. Additionally, histopathological examinations were conducted, and the accumulation of silver in biomarker organs was measured. The results indicate that silver tends to bioaccumulate in all biomarker organs in a dose- and time-dependent manner, except for the muscle tissue, where accumulation initially increased and subsequently decreased, demonstrating the fish's inherent ability for natural attenuation. Analysis of physiological data and integrated biomarker responses reveal that concentrations of 1/10th, 1/25th, and 1/50th of the LC50 can induce stress in the fish, while exposure to 1/100th of the LC50 shows minimal to no stress response. Overall, this study provides valuable insights into the toxicity and physiological responses of fish exposed to poultry waste biosynthesized AgNPs, offering potential applications in aquaculture while harnessing their unique features.

Toxicity Evaluation, Plant Growth Promotion, and Anti-fungal Activity of Endophytic Bacteria-Mediated Silver Nanoparticles

In recent years, the uses of silver nanoparticles have increased, which lead to nanoparticles discharge into aquatic bodies which may, if not well controlled, have harmful effect on different organisms. This calls for the need to constantly evaluate the toxicity level of nanoparticles. In this study, green biosynthesized silver nanoparticles mediated by endophytic bacteria Cronobacter sakazakii (CS-AgNPs) were subjected to toxicity evaluation by brine shrimp lethality assay. The ability of CS-AgNPs to improve plant growth by nanopriming of Vigna radiata L seeds treated with different concentrations (1ppm, 2.5ppm, 5ppm and 10ppm) in order to enhance biochemical constituents was investigated, also its inhibitory effect to growth of phytopathogenic fungi Mucor racemose was examined. Results showed that Artemia salina treated with CS-AgNPs exhibited good hatching percentage and LC50 value of 688.41 µg/ml when Artemia salina eggs were exposed to CS-AgNPs during hatching. Plant growth was enhanced at 2.5ppm CS-AgNPs, with increased photosynthetic pigments, protein, and carbohydrate content. This study suggests that silver nanoparticles synthesized via endophytic bacteria Cronobacter sakazakii are safe to use and can be utilized as means of combating plant fungal pathogens.

In situ microwave-assisted preparation of NS-codoped carbon dots stabilized silver nanoparticles as an off-on fluorescent probe for trace Hg2+ detection

An off-on fluorescent probe (NS-CDs-AgNPs) was synthesized based on a one-pot microwave process by utilizing N, S co-doping carbon dots (NS-CDs) and silver nitrate as precursors. The significant peak of NS-CDs-AgNPs at 393 nm in ultraviolet spectrum indicated silver nanoparticle (AgNPs) were successfully synthesized. A faint blue fluorescence emission (442 nm) was displayed when excited NS-CDs-AgNPs at 371 nm. A remarkable fluorescence recovery was observed upon adding of trance Hg2+, whereas the other heavy metal ions did not elicit this response. The reason for this phenomenon was revealed in this work that a spontaneous redox reaction occurred between NS-CDs-AgNPs and Hg2+, which leaded to the formation of NS-CDs-Agn-2NPsHg complexes. On the basis of this mechanism, a new off-on fluorescent analytical method was constructed for Hg2+ detection with linear range of 10-400 nM (R2 = 0.9941), and the detection limit (LOD) of 5.16 nM. Additionally, satisfactory recovery (90.28%-106.13%) and the relative standard deviation (RSD) (RSD＜5.21%) were obtained in water sample detection. More importantly, the NS-CDs-AgNPs exhibited lower cytotoxicity and better biocompatibility, indicating a huge potential in cell imaging and clinical medicine.

Silver nanoparticle-modified melt-blown polypropylene: Antibacterial and antifungal properties and antiviral activity against SARS-CoV-2

Melt-blown polymer fiber materials are frequently used in the face mask manufacturing. In the present work, a melt-blown polypropylene tape was modified by silver nanoparticles using chemical metallization. The silver coatings on the fiber surface consisted of crystallites 4-14 nm in size. For the first time, these materials were comprehensively tested for antibacterial, antifungal and antiviral activity. The silver-modified materials showed antibacterial and antifungal activities, especially at high concentrations of silver, and were found to be efficient against the SARS-CoV-2 virus. The silver-modified fiber tape can be used in the face mask manufacturing and as an antimicrobial and antiviral component in filters of liquid and gaseous media.

Improving water treatment using a novel antibacterial kappa-carrageenan-coated magnetite decorated with silver nanoparticles

In this study, we aimed to fabricate an enhanced antibacterial agent to act against pathogenic bacteria in aqueous environments. To achieve this, silver nanoparticles (AgNPs) were inlaid on a kappa-carrageenan (KC) base and coated on Fe3O4 magnetic cores (Fe3O4@KC@Ag). Superparamagnetic Fe3O4 nanoparticles were designed at the center of the composite nanostructure, allowing magnetic recovery from aqueous media in the presence of a magnet. The synthesized nanoconjugate was characterized in each step using XRD, FT-IR, EDX, FE-SEM, TEM, DLS, VSM, and disk-diffusion antibacterial method. Results show that the nanocomposite system is formed, while the magnetic properties remain practically stable. The agglomeration of the AgNPs was decreased by the trap-like function of KC coating, which resulted in an improved antibacterial activity for the Fe3O4@KC@Ag formulation. These findings suggest that Fe3O4@KC@Ag nanocomposites could be promising agents for combating bacterial infections in aqueous environments.

Bacterial Polysaccharide-Stabilized Silver Nanoparticles Photocatalytically Decolorize Azo Dyes

Bacterial polysaccharide is advantageous over plant, algal, and fungal polysaccharides in terms of stability, non-toxicity, and biodegradable nature. In addition, bacterial cell wall polysaccharide (CPs) is very little explored compared to exopolysaccharide. In this study, CPs have been isolated from thermotolerant Chryseobacterium geocarposphaerae DD3 (CPs3) from textile industry dye effluent. Structural characterization of the CPs was done by different techniques, viz., scanning electron microscopy-energy dispersive X-ray spectrometry (SEM-EDX), atomic force microscopy (AFM), Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR) spectroscopy, and thermogravimetric analysis (TGA). CPs3 demonstrated compact non-porous amorphous surface composed of evenly distributed macromolecular lumps. TGA revealed a high thermostability (~ 350 °C) of the polysaccharide. FTIR and NMR confirm the polysaccharidic nature of the polymer, consisting of glucose units linked by both β-(1 → 3) and β-(1 → 4) glycosidic bonds. The functional properties of CPs3 were evaluated for industrial use as additive, especially antibacterial, emulsification, and flocculation capacities. A single-step green synthesis of silver nanoparticle (AgNP) was performed using CPs3. AgNP was characterized using ultraviolet-visible (UV-Vis) spectroscopy, transmission electron microscopy (TEM), AFM, and particle size analyses. The CPs3-stabilized AgNP exhibited potential photocatalytic activity against a broad range of azo dyes, congo red (88.33 ± 0.48%), methyl red (76.81 ± 1.03%), and malachite green (47.34 ± 0.90%) after only 3 h of reaction. According to our knowledge, this is the first report on CPs from C. geocarposphaerae. The results demonstrated multifunctionality of CPs3 in both prospective, CPs3 as additive in biotechnology industry as well as Cps3-stabilized AgNP for bioremediation of azo dye.

Comparison of Selenic Acid and Pyruvic Acid-Loaded Silver Nanocarriers Impact on Colorectal Cancer Viability

Colorectal cancer (CRC) is a leading cause of morbidity and death worldwide. As current cancer drugs are ineffective, new solutions are being sought in other fields, including nanoscience. Similarly, silver nanoparticles play an important role in the pharmaceutical industry as they act as anti-cancer agents with less harmful effects and are usually 1 to 100 nm in size. Selenic acid (SA) and pyruvic acid (PA) are involved in various metabolic pathways in cancer. For this reason, we decided to detect their influence on colorectal cancer using silver-based (Ag) nanocarriers. DLS, Zetasizer, SEM and UV-Vis analyses were used to characterize AgSA and AgPA. A UV spectrophotometer was used to analyze the release of the NPs. MTT analyses were used to measure the viability of HCT116 and HUVEC cells, and IC50 values were calculated using GraphPad Prism. The indicated dosage and particle size of AgSA NPs proved to be suitable for cytotoxicity. Moreover, injection of these nanoparticles into non-cancer cells proved safe due to their minimal toxicity. In contrast, the AgPA NPs have no cytotoxicity and induce proliferation of HCT116 cells. Finally, only the synthesised AgSA nanoparticles could be used for advanced cancer therapy, which is both inexpensive and has minimal side effects.

Green synthesis of nano silver-embedded carboxymethyl starch waste/poly vinyl alcohol hydrogel with photothermal sterilization and pH-responsive behavior

Bacterial wound infections remain a significant health issue of great concern. Hence, there is a need to develop a novel material with antibacterial properties and smart functions. In this study, the effects of silver nanoparticles content (AgNPs) on properties of photothermal and pH-responsive nanocomposite hydrogels were investigated. The nanocomposite hydrogel samples were prepared using cassava starch waste modified by carboxymethylation (CMS), and mixed with poly vinly alcohol (PVA) and tannic acid (TA). The presence of AgNPs in the hydrogel samples enhanced antibacterial activities and photothermal conversion ability. The use of as-prepared hydrogel using 200 mM silver nitrate (H-AgNPs-200) combined with near infrared (NIR) radiation produced 100 % antibacterial efficiency for Escherichia coli (E.coli) and 98.2 % for Staphylococcus aureus (S.aureus). Furthermore, the H-AgNPs-200 also provided the highest storage modulus at 87.9 kPa. The obtained nanocomposite hydrogel was shown to exhibit pH-responsive release of TA. Under NIR radiation, higher release of TA at different pH was observed. The cytotoxicity study indicated that the nanocomposite hydrogels had good biocompatibility. Hence, the development of nanocomposite hydrogel-based CMS from cassava starch waste/PVA/AgNPs is a promising and sustainable approach where agro-waste product is used as the base material for medical application in wound dressing.

Study on injectable silver-incorporated calcium phosphate composite with enhanced antibacterial and biomechanical properties for fighting bone cement-associated infections

Although commonly used in orthopedic surgery, bone cements often face a high risk of post-operative infection. Developing bone cement with antibacterial capability is an effective path for eliminating implant-associated infections. Herein, the potential of silver ions (Ag⁺) and silver nanoparticles (AgNPs) in modifying CPC for long-term antibacterial property was investigated. Ag⁺ ions or AgNPs of various concentrations were incorporated in starch-modified calcium phosphate bone cement (CPB) to obtain Ag⁺-containing (Ag⁺@CPB) and AgNPs-containing (AgNP@CPB) bone cements. The results showed that all silver-containing CPBs had setting times of about 25-40 min, compressive strengths of greater than 22 MPa, high cytocompatibility but inhibitory effect on Staphylococcus aureus growth. After soaking for 1 week, the mechanical properties and the cytocompatibility of all cements revealed no significant changes, but only CPB with a relatively high content of Ag⁺ (H-Ag⁺@CPB) maintained good antibacterial capability over the tested time period. In addition, all the cements showed high injectability and interdigitating capability in cancellous bone and demonstrated augmentation effect on the cannulated pedicle screws fixation in the Sawbones model. In summary, the sustainable antibacterial capability and enhanced biomechanical properties demonstrated that Ag⁺ ions were more suitable for the fabrication of antibacterial CPC compared to AgNPs. Also, the H-Ag⁺@CPB, with good injectability, high cytocompatibility, good interdigitating and biomechanical property in cancellous bone, and sustainable antibacterial effects, bears great potential for the treatments of bone infections or implant-associated infections.

Implications of ferroptosis in silver nanoparticle-induced cytotoxicity of macrophages

Metal nanoparticles (NPs) are widely used in daily life and commercial activities owing to their unique physicochemical properties. Consequently, there is an increasing risk of daily and occupational exposure to metal NPs, which raises concerns regarding their health hazards. Programmed cell deaths (PCDs) have been clarified to be involved in metal NP-induced cytotoxicity, including apoptosis, autophagy, and pyroptosis. However, whether and how ferroptosis, a newly recognized PCD, contributes to metal NP-induced cell death remain unclear. In this study, we investigated the ferroptotic effects of two representative metal NPs, silver nanoparticles (AgNPs) and gold nanoparticles (AuNPs), on macrophages in vitro. Our results revealed that AgNPs, rather than AuNPs, induced non-apoptotic PCD, accompanied by lipid peroxidation and iron homeostasis disorders, which are two hallmarks of ferroptosis, in macrophages. Treatment with a ferroptosis inhibitor (ferrostatin-1) and iron chelator (deferoxamine) reversed AgNP-induced PCD, corroborating the induction of ferroptosis upon exposure to AgNPs. Moreover, our results revealed that smaller AgNPs elicited greater ferroptotic effects on macrophages than larger ones. Importantly, ferroptosis in AgNP-treated macrophages was mainly triggered by AgNPs per se rather than by Ag ions. Overall, our study highlights the ferroptotic effects elicited by AgNPs in macrophages, which will promote the understanding of their cytotoxic effects and facilitate the safer design of metal nanoproducts.

Antibacterial, antiviral, and biodegradable collagen network mask for effective particulate removal and wireless breath monitoring

Functional face masks that can effectively remove particulate matter and pathogens are critical to addressing the urgent health needs arising from industrial air pollution and the COVID-19 pandemic. However, most commercial masks are manufactured by tedious and complicated network-forming procedures (e.g., meltblowing and electrospinning). In addition, the materials used (e.g., polypropylene) have significant limitations such as a lack of pathogen inactivation and degradability, which can cause secondary infection and serious environmental concerns if discarded. Here, we present a facile and straightforward method for creating biodegradable and self-disinfecting masks based on collagen fiber networks. These masks not only provide superior protection against a wide range of hazardous substances in polluted air, but also address environmental concerns associated with waste disposal. Importantly, collagen fiber networks with naturally existing hierarchical microporous structures can be easily modified by tannic acid to improve its mechanical characteristics and enable the in situ production of silver nanoparticles. The resulting masks exhibit excellent antibacterial (>99.99%, 15 min) and antiviral (>99.999%, 15 min) capabilities, as well as high PM_2.5 removal efficiency (>99.9%, 30 s). We further demonstrate the integration of the mask into a wireless platform for respiratory monitoring. Therefore, the smart mask has enormous promise for combating air pollution and contagious viruses, managing personal health, and alleviating waste issues caused by commercial masks.

Interfacial deposition of Ag nanozyme on metal-polyphenol nanosphere for SERS detection of cellular glutathione

The low polarization and low Raman cross section characteristics of glutathione (GSH) make it challenging to directly detect GSH molecules through surface enhanced Raman scattering (SERS) technology. Development of nanostructures for indirect detection of GSH applied to the SERS platform is of great interest. Herein, silver nanoparticles (Ag NPs)/copper-polyphenol colloidal spheres (denoted as CuTA@Ag) with adjustable Ag NPs coverage are prepared by deposition of Ag NPs on the metal-polyphenol colloidal spheres via an interfacial polyphenol reduction method. The size and density of the Ag NPs deposited on the out layer can be readily adjusted by tailoring the concentrations of silver precursor. It leads to activity difference for the nanozyme and SERS characteristics. The SERS properties of the obtained CuTA@Ag are studied using oxTMB, catalytic products of nanozyme, as the probing molecules. They provide satisfactory SERS performance with a low detection limit of 10^-7 M (S/N = 3) and linear determination in the 1-100 μM range for GSH. Moreover, it is further able to detect the glutathione content in cancer cells with well accurate and reproducible capability, catching the signs of rising cancer marker levels. This work proposes structurally tunable nanomaterials platform for a catalytic-based SERS assay, which is expected to utilize the high sensitivity of SERS tool for GSH detection in the cellular environment.

Silver nanoparticles induced with aqueous black carpenter ant extract selectively inhibit the growth of Pseudomonas aeruginosa

Aqueous black carpenter ant extract (ABCAE) was used to synthesize silver nanoparticles (AgNPs). The ABCAE was rich in water-soluble compounds such as hydrophilic polypeptides that behaved as both reducing and stabilizing agents for generating AgNPs from Ag⁺ ion precursors. The diameter of the observed AgNPs was mostly in the range of 20-60 nm. The AgNPs were tested as an antibacterial agent for the growth inhibition of two pathogenic bacteria (Pseudomonas aeruginosa ATCC 27853, Staphylococcus aureus ATCC 27661) and one common bacteria (Escherichia coli K12 ATCC 10798). Disk diffusion test showed that the AgNPs selectively inhibited the growth of P. aeruginosa but not for the other two species, suggesting the potential application of the green-chemically synthesized AgNPs as a selective antibacterial agent without harming other beneficial bacteria.

Transformation, Absorption and Toxicological Mechanisms of Silver Nanoparticles in the Gastrointestinal Tract Following Oral Exposure

Oral exposure is known as the primary way for silver nanoparticles (AgNPs), which are commonly used as food additives or antibacterial agents in commercial products, to enter the human body. Although the health risk of AgNPs has been a concern and extensively researched over the past few decades, there are still numerous knowledge gaps that need to be filled to disclose what AgNPs experience in the gastrointestinal tract (GIT) and how they cause oral toxicity. In order to gain more insight into the fate of AgNPs in the GIT, the main gastrointestinal transformation of AgNPs, including aggregation/disaggregation, oxidative dissolution, chlorination, sulfuration, and corona formation, is first described. Second, the intestinal absorption of AgNPs is presented to show how AgNPs interact with epithelial cells and cross the intestinal barrier. Then, more importantly, we make an overview of the mechanisms underlying the oral toxicity of AgNPs in light of recent advances as well as the factors affecting the nano-bio interactions in the GIT, which have rarely been thoroughly elaborated in published literature. At last, we emphatically discuss the issues that need to be addressed in the future to answer the question "How does oral exposure to AgNPs cause detrimental effects on the human body?".

Synthesis, characterization and optimization of chicken bile-mediated silver nanoparticles: a mechanistic insight into antibacterial and antibiofilm activity

The fast-growing urbanization and slow progress in the field of waste management have led to the accumulation of large quantities of animal wastes. The present work focused on the synthesis of low-cost and eco-friendly chicken bile juice-mediated silver nanoparticles (BJ-AgNP). Results reveal that bile juices have enough potentiality towards the synthesis of almost uniform sizes (average size < 50 nm) of BJ-AgNPs which remains stable for more than 6 months. Response surface methodology (RSM) successfully demonstrated the optimised condition of BJ-AgNP synthesis. Factors like concentration of salt and bile extract and temperature are significantly responsible for nanoparticle synthesis. The synthesis of nanoparticle was further characterized using UV-Vis, TEM, FESEM, XRD, FTIR, TGA, and EDS. The synthesised nanoparticle showed excellent bactericidal activity against both Gram positive and Gram negative bacteria with MIC and MBC of 40 and 50 μg/mL for Bacillus subtilis (MTCC-441) and 60 and 60 μg/mL for Eschecheria coli (MTCC-1687) respectively. The synthesised nanoparticle also exhibited as an antibiofilm activity against B. subtilis, with ~89% biofilm inhibition efficacy at 4 X MIC, having optimal bacterial concentration of 10⁶ CFU/mL. Therefore, the present findings clearly demonstrated that an absolute animal waste could be a valuable ingredient in the field of therapeutic nanoscience.

Silver-dendrimer nanocomposite as emerging therapeutics in anti-bacteria and beyond

To develop next-generation nanomedicine, theranostic nanotherapeutic strategies are increasingly being emphasized. In recent years, it is observed that the effective lifetime of anti-bacterial and anti-cancer agent is diminishing, which undermines the economic incentives necessary for clinical development and therapeutic applications. Thus, novel formulations ought to not only kill drug resistant strains and cancerous cells but also inhibit their formation. Recently, metallic nanoparticles [for example- silver (Ag) nanoparticles] have been widely investigated for their biomedical applications. The so-called applications necessitate the inclusion of these nanoparticles inside polymeric matrices (for example- dendrimer) leading to chemical functionalization of the metallic nanoparticles. Silver and silver nanoparticles' antibacterial activity has already been well established over years. Dendrimers due to their homogeneous highly branched structure and uniform composition are perfectly suitable for the inclusion of silver nanoparticles [Ag NPs]. Recently, the increasing trend in the development of Ag-dendrimer nanocomposites is attributed to the excellent antibacterial activity of Ag as well as dendrimer's unique properties like variable functional terminal ends and potential antibacterial effect necessarily. This review provides an informative overview regarding the numerous aspects of bactericidal and other biomedical applications of Ag-dendrimer nanocomposites, particularly emphasizing analysis of existing research and prospective worth to the pharmaceutical sector in future.

Iron-rich coal fly ash-polydopamine-silver nanocomposite (IRCFA-PDA-Ag NPs): tailored material for remediation of methylene blue dye from aqueous solution

Water pollution has become one of the most acute environmental problems. One of the pollutants coming to water bodies from industries are dyes, which are harmful to human health, living organisms, and the esthetic appearance of water. Most dyes are toxic, carcinogenic, rarely biodegradable, and highly soluble in water. Therefore, industrial wastewater treatment has become important. Adsorption technique of removal of dyes from water is simple, efficient, and inexpensive as compared to other techniques. Adsorption efficiency depends on the type and surface area of adsorbents. Iron-rich coal fly ash (IRCFA)-Polydopamine (PDA)@ Silver (Ag) nanocomposite was prepared by separating the iron-rich part (IRCFA) from coal fly ash and coated with polydopamine. IRCFA was mixed with 10 mM tris buffer solution containing 1 g dopamine. The prepared IRCFA-PDA was added to an aqueous solution of silver nitrate, heated at 60 °C, and then 30 mL of flower waste extract was added to this solution. Solid IRCFA-PDA@Ag was obtained, and the prepared nanocomposite was used for the removal of methylene blue (MB) dye from water. The nanocomposite used was prepared by a cost-effective method and has high reusability, separability, and fast regeneration ability. The mechanism of removal of MB dye has been discussed in detail.

Kinetics, isotherms, and mechanism of removing cationic and anionic dyes from aqueous solutions using chitosan/magnetite/silver nanoparticles

Modified magnetite chitosan with silver nanoparticles was synthesized and tested for removing cationic and anionic dyes in aqueous solutions. Initial dye concentration, pH, and contact time were examined. Results showed that pH (4.0) was optimal for removing anionic dyes (methyl orange) and pH 8.0 for removing cationic dyes (methylene blue). According to these results, zeta potentials were found to be 8.43 and - 39.17 mV at pH 4.0 and 8.0, respectively. So, it is attracted to positively charged cationic dyes in an alkaline medium and negatively charged anionic dyes in an acidic medium because of their opposite charges. Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectra (XPS), thermal gravimetric analysis (TGA), and zeta potential measurements were used to characterize the synthesized nanosorbents. A pseudo-second-order kinetic model is fitted with the Langmuir adsorption model, with an adsorption capacity of 417 and 476 mg/g for methyl orange and methylene blue, respectively. For both dyes, modified magnetite chitosan with silver nanoparticles showed high regeneration capability and recovery for up to four cycles without adsorption efficiency loss. Furthermore, modified magnetite chitosan with silver nanoparticles, as prepared in the present study, was demonstrated to be an effective adsorbent for organic pollutants in wastewater.

Characterization of Firmiana colorata (Roxb.) leaf extract and its silver nanoparticles reveal their antioxidative, anti-microbial, and anti-inflammatory properties

Nanotechnology is the integrative science in the field of physics, chemistry and biology. For the synthesis of silver nanoparticles, a simple approach was applied using Firmiana colorata (Roxb.) aqueous leaf extract. During the synthesis of this silver nanoparticle, the solution color changes from green to deep brown due to the reduction of silver. The phytocompounds present in the Firmiana colorata (Roxb.) leaf extract acts as a reducing as well as a capping agent. Identifying the presence of bioactive compounds responsible for the reduction of silver was extensively characterized by UV-Vis spectrophotometer, FTIR, SEM, and EDX. Moreover, to know the efficacy of the silver nanoparticles (AgNps) antioxidant and antimicrobial studies were evaluated against the human pathogenic bacteria. Furthermore, GC-MS analysis of the leaf extract of Firmiana colorata has been done followed by the in-silico molecular docking against the Anti-inflammatory and oxidative protein. Here within this study, a comparative evaluation was done among the Firmiana colorata (Roxb.) leaf extract and the synthesized silver nanoparticles. Results indicate that ethnomedicinally lesser known Firmiana colorata (Roxb.) and AgNps have the potency to act as anti-inflammatory, antioxidative, and antimicrobial agents.

Particle size-dependent effects of silver nanoparticles on swim bladder damage in zebrafish larvae

Particle size-dependent biological effects of silver nanoparticles (AgNPs) are of great interest; however, the mechanism of action of silver ions (Ag⁺) released from AgNPs concerning AgNP particle size remains unclear. Thus, we evaluated the influence of particle size (20, 40, 60, and 80 nm) on the acute 96-h bioaccumulation and toxicity (swim bladder damage) of AgNPs in zebrafish (Danio rerio) larvae, with a focus on the mechanism of action of Ag⁺ released from differently sized AgNPs. The 40- and 60-nm AgNPs were more toxic than the 20- and 80-nm versions in terms of inflammation and oxidative damage to the swim bladder, as indicated by inhibition of type 2 iodothyroxine deiodinase enzyme activity, mitochondrial injury, and reduced 30-50% adenosine triphosphate content. Furthermore, up-regulation and down-regulation of swim bladder development-related gene expression was not observed for pbx1a and anxa5, but up-regulation expression of shha and ihha was observed with no statistical significance. That 20-nm AgNPs were less toxic was attributed to their rapid elimination from larvae in comparison with the elimination of 40-, 60-, and 80-nm AgNPs; thus, less Ag⁺ was released in 20-nm AgNP-exposed larvae. Failed inflation of swim bladders was affected by released Ag⁺ rather than AgNPs themselves. Overall, we reveal the toxicity contribution of Ag⁺ underlying the observed size-dependent effects of AgNPs and provide a scientific basis for comprehensively assessing the ecological risk and biosafety of AgNPs.

Functional silver nanoparticles synthesis from sustainable point of view: 2000 to 2023 ‒ A review on game changing materials

The green and facile synthesis of metallic silver nanoparticles (AgNPs) is getting tremendous attention for exploring superior applications because of their small dimensions and shape. AgNPs are already proven materials for superior coloration, biocidal, thermal, UV-protection, and mechanical performance. Originally, some conventional chemical-based reducing agents were used to synthesize AgNPs, but these posed potential risks, especially for enhanced toxicity. This became a driving force to innovate plant-based sustainable and green metallic nanoparticles (NPs). Moreover, the synthesized NPs using plant-based derivatives could be tuned and regulated to achieve the required shape and size of the AgNPs. AgNPs synthesized from naturally derived materials are safe, economical, eco-friendly, facile, and convenient, which is also motivating researchers to find greener routes and viable options, utilizing various parts of plants like flowers, stems, heartwood, leaves and carbohydrates like chitosan to meet the demands. This article intends to provide a comprehensive review of all aspects of AgNP materials, including green synthesis methodology and mechanism, incorporation of advanced technologies, morphological and elemental study, functional properties (coloration, UV-protection, biocidal, thermal, and mechanical properties), marketing value, future prospects and application, especially for the last 20 years or more. The article also includes a SWOT (Strengths, weaknesses, opportunities, and threats) analysis regarding the use of AgNPs. This report would facilitate the industries and consumers associated with AgNP synthesis and application through fulfilling the demand for sustainable, feasible, and low-cost product manufacturing protocols and their future prospects.

Synthesis of silver nanoparticles from Indian red yeast rice and its inhibition of biofilm in copper metal in cooling water environment

The development of environmentally acceptable benign techniques using purely natural methods is a cost-effective procedure with long-term benefits in all areas. With this consideration, myco synthesized silver nano particles (AgNPs) were studied and it acted as an impending corrosion inhibitor in the environment. Initially, AgNPs were evaluated by physical and surface characterizations and this evidence demonstrated that RYRE's water-soluble molecules played an essential role in the synthesis of AgNPs in nano spherical size. The myco synthesized of AgNPs has showed an antibacterial activity against corrosive bacteria in cooling water system (CWS). Hence, the AgNPs were used in biocorrosion studies as an anticorrosive agent along with AgNO₃ and RYRE was also checked. For this experiment, the copper (Cu) metal (CW024) which is commonly used was selected, the result of corrosion rate was decreased, and inhibition efficiency (82%) was higher in the presence of AgNPs in system IV. Even though, AgNO₃ and RYRE had contributed significant inhibition efficiency on Cu at 47% and 61%, respectively. According to XRD, the reaction of AgNPs on Cu metal resulted in the formation of a protective coating of Fe₂O₃ against corrosion. EIS data also indicated that it could reduce the corrosion on the Cu metal surface. All of these findings point out the possibility that the myco-synthesized AgNPs were an effective copper metal corrosion inhibitor. As a result, we encourage the development of myco-synthesized AgNPs, which could be useful in the industrial settings.

Toxicity of synthesized silver nanoparticles in a widespread fish: A comparison between green and chemical

Metallic nanoparticles are gaining importance in various fields of life due to their large surface area to volume ratio. However, metallic nanoparticles pose different toxic effects on fish when they appear with different shapes and compositions in water. Herein the present study was designed to evaluate the median (LC₅₀) and sub-lethal (1/10th of LC₅₀) concentrations of Ag-Green NPs, 700 μg/L for Ag-Chem NPs, and 50 μg/L for Ag₂O-Chem NPs were confirmed in Hypophthalmichthys molitrix. Furthermore, exposure of H. molitrix fingerlings to 10 % of LC₅₀ concentration of these particles induced significantly higher (p < 0.05) activities of serum alanine transaminase, aspartate aminotransferase, lactate dehydrogenase, white blood cells, acetylcholinesterase and catalase, superoxide dismutase, peroxidase, relative gene expressions of antioxidant enzymes, heat shock protein (Hsp70), hypoxia- inducible factor 1-alpha (HIF-1α) and lipid peroxidase level than the control, but decreased hematological parameters with less effects of Ag-Green NPs than chemically synthesized AgNPs. Moreover, the histopathological study also indicated morphological changes in the liver and gills of treated fish groups. The comparative toxicity evaluation revealed the maximum negative effect of Ag₂O-Chem NPs followed by Ag-Chem NPs while Ag-Green NPs showed the least toxic effects. Based on our results, replacement of chemically synthesized NPs to green synthesized AgNPs can be recommended in large scale application to reduce the noxious effects to aquatic environment.