Femtosecond laser ablation-assisted synthesis of silver nanoparticles in organic and inorganic liquids medium and their antibacterial efficiency

Refining shape and size of silver nanoparticles using ion irradiation for enhanced and homogeneous SERS activity

We present green synthesis of silver nanoparticles in water using unirradiated and Ag15 + ion irradiated phytoextracts of Bergenia Ciliata leaf, Eupatorium adenophorum leaf, Rhododendron arboreum leaf and flower. The use of different plant extracts and their subsequent ion irradiation allow for successful refinement of nanoparticle size and morphology. Due to changes in reducing and capping agents the nanoparticle surface functionalization also varies which not only controls the morphology but also allows for surface oxidation and aggregation processes. In this work, we have synthesized silver nanoparticles which exhibit sizes in the range from 13 to 24 nm and having shapes like spherical, quasispherical, trigonal, hexagonal, cylindrical, dendritic assemblies, and porous nanoparticles. Owing to changes in the size and shape of the nanoparticles, their direct bandgap (2.05 eV - 2.48 eV) and local surface plasmon resonance (420 nm - 490 nm) could also be tuned. These nanoparticles are examined as SERS substrates, where their enhancement factors, limit of detection for methylene blue, and SERS substrate homogeneity have been tested. It has been observed the nanoparticles synthesized using unirradiated plant extracts present an enhancement factor of 106 with a limit of detection 10- 8 M. Whereas nanoparticles with refined morphology and shapes upon irradiation present high enhancement factors of >107 and detection limit down to 10- 9 M. In addition, uniformity in Raman spectra over the SERS substrates has been obtained for selected Ag NPs substrates synthesized using irradiated extracts with minimum relative standard deviation in enhancement factor < 12%.

Recent Applications of Quantum Dots in Pharmaceutical Analysis

Nanotechnology has emerged as one of the most potential areas for pharmaceutical analysis. The need for nanomaterials in pharmaceutical analysis is comprehended in terms of economic challenges, health and safety concerns. Quantum dots (QDs)or colloidal semiconductor nanocrystals are new groups of fluorescent nanoparticles that bind nanotechnology to drug analysis. Because of their special physicochemical characteristics and small size, QDs are thought to be promising candidates for the electrical and luminescent probes development. They were originally developed as luminescent biological labels, but are now discovering new analytical chemistry applications, where their photo-luminescent properties are used in pharmaceutical, clinical analysis, food quality control and environmental monitoring. In this review, we discuss QDs regarding properties and advantages, advances in methods of synthesis and their recent applications in drug analysis in the recent last years.

Biogenic synthesis of novel nanomaterials and their applications

Despite the many benefits derived from the unique features and practicality of nanoparticles, the release of their toxic by-products or products from the synthesis stage into the environment could negatively impact natural resources and organisms. The physical and chemical methods for nanoparticle synthesis involve high energy consumption and the use of hazardous chemicals, respectively, going against the principles of green chemistry. Biological methods of synthesis that rely on extracts from a broad range of natural plants, and microorganisms, such as fungi, bacteria, algae, and yeast, have emerged as viable alternatives to the physical and chemical methods. Nanoparticles synthesized through biogenic pathways are particularly useful for biological applications that have high concerns about contamination. Herein, we review the physical and chemical methods of nanoparticle synthesis and present a detailed overview of the biogenic methods used for the synthesis of different nanoparticles. The major points discussed in this study are the following: (1) the fundamentals of the physical and chemical methods of nanoparticle syntheses, (2) the use of different biological precursors (microorganisms and plant extracts) to synthesize gold, silver, selenium, iron, and other metal nanoparticles, and (3) the applications of biogenic nanoparticles in diverse fields of study, including the environment, health, material science, and analytical chemistry.

Fast and easy synthesis of silver, copper, and bimetallic nanoparticles on cellulose paper assisted by ultrasound

This work focuses on a systematic method to produce Ag, Cu, and Ag/Cu metallic nanoparticles (MNPs) in situ assisted with ultrasound on cellulose paper. By tuning the concentration of AgNO3 and CuSO4 salt precursors and ultrasound time, combined with a fixed concentration of ascorbic acid (AA) as a reducing agent, it was possible to control the size, morphology, and polydispersity of the resulting MNPs on cellulose papers. Notably, high yield and low polydispersity of MNPs and bimetallic nanoparticles are achieved by increasing the sonication time on paper samples pre-treated with salt precursors before reduction with AA. Moreover, mechanical analysis on paper samples presenting well-dispersed and distributed MNPs showed slightly decreasing values of Young's modulus compared to neat papers. The strain at break is substantially improved in papers containing solely Ag or Cu MNPs. The latter suggests that the elastic/plastic transition and deformation of papers are tuned by cellulose and MNPs interfacial interaction, as indicated by mechanical analysis. The proposed method provides insights into each factor affecting the sonochemistry in situ synthesis of MNPs on cellulose papers. In addition, it offers a straightforward alternative to scale up the production of MNPs on paper, ensuring an eco-friendly method.

Photodetection Properties of CdS/Si Heterojunction Prepared by Pulsed Laser Ablation in DMSO Solution for Optoelectronic Application

The high-quality n-type CdS on a p-type Si (111) photodetector device was prepared for the first time by a one-pot method based on an ns laser ablation method in a liquid medium. Cadmium target was ablated in DMSO solution, containing sulfur precursor, and stirred, assisting in 1D-growth, to create the sulfide structure as CdS nano-ropes form, followed by depositing on the Si-substrate by spin coating. The morphological, structural, and optical characteristics of the CdS structure were examined using X-ray diffraction, transmission, and scanning electron microscopy, photoluminescence, and UV-VIS spectroscopy. From X-ray diffraction analysis, the growing CdS spheres have a good crystal nature, with a high purity and desired c-axis orientation along the (002) plane, and the crystallinity was around 30 nm. According to optical characterization, high transparency was found in the visible-near-infrared areas of the electromagnetic spectrum, and the CdS spheres have a direct optical energy band gap of 3.2 eV. After that, the CdS/Si hetero-structured device was found to be improved remarkably after adding CdS. It showed that the forward current is constantly linear, while the dark current is around 4.5 µA. Up to a bias voltage of 4 V, there was no breakdown, and the reverse current of the heterojunctions somewhat increased with reverse bias voltage, while the photocurrent reached up to 580 and 690 µA for using 15 and 30 W/cm2 light power, respectively. Additionally, the ideal factors for CdS/Si heterojunction were 3.1 and 3.3 for 15 and 30 W/cm2 light power, respectively. These results exhibited high performance compared to the same heterojunction produced by other techniques. In addition, this opens the route for obtaining more enhancements of these values based on the changing use of sulfide structures in the heterojunction formation.

Femtosecond laser ablation in liquid synthesis of iron-oxidation nanoparticles with saturable absorption performance

"Naked" ferroferric-oxide nanoparticles (FONPs) synthesized by a femtosecond laser ablation on a bulk stainless steel in liquid were applied to the Nd: YVO₄ laser to achieve passive Q-switched pulse laser output. Without the pollution of ligand, the inherent light characteristic of "naked" FONPs was unaffected. The analysis of the morphological characteristics, dominant chemical elements, and phase composition of the FONPs showed that they were mainly composed of Fe₃O₄, which was spherical with an average diameter of 40 nm. The electron transition and orbital splitting of the iron element's octahedral center position under the laser-driven were considered the primary mechanisms of saturable absorption of Fe₃O₄ nanoparticles.

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.

Silver Nanoparticles Produced by Laser Ablation and Re-Irradiation Are Effective Preventing Peri-Implantitis Multispecies Biofilm Formation

Implant-associated infection due to biofilm formation is a growing problem. Given that silver nanoparticles (Ag-NPs) have shown antibacterial effects, our goal is to study their effect against multispecies biofilm involved in the development of peri-implantitis. To this purpose, Ag-NPs were synthesized by laser ablation in de-ionized water using two different lasers, leading to the production of colloidal suspensions. Subsequently, part of each suspension was subjected to irradiation one and three times with the same laser source with which it was obtained. Ag-NPs were immobilized on the surface of titanium discs and the resultant materials were compared with unmodified titanium coupons. Nanoparticles were physico-chemically analysed to determine their shape, crystallinity, chemical composition, and mean diameter. The materials were incubated for 90 min or 48 h, to evaluate bacterial adhesion or biofilm formation respectively with Staphylococcus aureus or oral mixed bacterial flora composed of Streptococcus oralis, Actinomyces naeslundii, Veionella dispar, and Porphyromonas gingivalis. Ag-NPs help prevent the formation of biofilms both by S. aureus and by mixed oral bacterial flora. Nanoparticles re-irradiated three times showed the biggest antimicrobial effects. Modifying dental implants in this way could prevent the development of peri-implantitis.

The effect of AgNPS bio-functionalization on the cytotoxicity of the yeast Saccharomyces cerevisiae

This work used Sedum praealtum leaf extract to synthesize silver nanoparticles (AgNPs) in a single step. The cytotoxicity of AgNPs was studied with the yeast Saccharomyces cerevisiae W303-1. In addition, the antioxidant activity of the DPPH radical was studied both in the extract of S. praealtum and in the AgNPs. UV-Vis spectroscopy determined the presence of AgNPs by the location of the surface plasmon resonance (SPR) band at 434 nm. TEM and XRD analyzes show AgNPs with fcc structure and hemispherical morphology. Also, AgNPs range in size from 5 to 25 nm and have an average size of 14 nm. 1H NMR, FTIR, and UV-Vis spectroscopy techniques agreed that glycosidic compounds were the main phytochemical components responsible for the reduction and stabilization of AgNPs. In addition, AgNPs presented a maximum of 12% toxicity in yeast attributed to the generation of ROS. Consequently, there was low bioactivity because glycoside compounds cover the biosynthesized AgNPs from S. praealtum. These findings allow applications of AgNPs involving contact with mammals and higher organisms.

Modification on antibacterial activity of PVC/PVDF blend filled with CuO NPs using laser ablation technique

Nanocomposite of polyvinyl chloride (PVC)/polyvinylidene fluoride (PVDF) have been in situ synthesized. Copper oxide nanoparticles (CuONPs) have been prepared via using the laser ablation technique. Nanoparticles were added to the blend. The properties of the blend were studied before and after adding CuONPs. These properties were characterized by different techniques. Antimicrobial activity of the prepared nanocomposite film was investigated. FTIR data show vibrational spectral bands and the shift of the bands is related to the interaction and the complexation that occurs between blend and nanoparticles. Structural properties and crystallinity of the samples were investigated using XRD diffraction. XRD results illustrated the effect of CuONPs at two new peaks 2θ = 26.25º and 38.41º. These results confirmed the interaction CuO NPs and PVDF/PVC matrix. UV–Visible analyses confirmed the existing of copper oxide nanoparticles and were also used for determining the optical absorption edge. The absorption edges have been obtained at 430–520 nm for all of the doping films. The obtained values for indirect and direct bandgaps were reduced by raising the nanoparticles because of the presence of charge transfer between PVC/PVDF and CuONPs. SEM images illustrateed the presence of CuONPs on the surface of the blend and the morphology changes which occurred to the blend. The antibacterial activity for the nanocomposite proved the antimicrobial effect of copper oxide nanoparticles. The prepared PVC/PVDF/CuONPs are potentially suggesting to be applied for biomedical applications.

Influence of Laser Process Parameters, Liquid Medium, and External Field on the Synthesis of Colloidal Metal Nanoparticles Using Pulsed Laser Ablation in Liquid: A Review

Pulsed laser ablation in liquid, used for nanoparticle synthesis from solid bulk metal targets (a top-down approach), has been a hot topic of research in the past few decades. It is a highly efficient and ‘green’ fabrication method for producing pure, stable, non-toxic (ligand-free), colloidal nanoparticles, which is often challenging using traditional chemical methods. Due to the short time scale interaction between the laser pulses and the target, it is difficult to achieve complete control on the physical characteristics of metallic nanoparticles. Laser process parameters, liquid environment, and external fields vastly effect the shape and structure of nanoparticles for targeted applications. Past reviews on pulsed laser ablation have focused extensively on synthesising different materials using this technique but little attention has been given to explaining the dependency aspect of the process parameters in fine-tuning the nanoparticle characteristics. In this study, we reviewed the state of the art literature available on this technique, which can help the scientific community develop a comprehensive understanding with special insights into the laser ablation mechanism. We further examined the importance of these process parameters in improving the ablation rate and productivity and analysed the morphology, size distribution, and structure of the obtained nanoparticles. Finally, the challenges faced in nanoparticle research and prospects are presented.

Recent Advances and Mechanistic Insights into Antibacterial Activity, Antibiofilm Activity, and Cytotoxicity of Silver Nanoparticles

The substantial increase in multidrug-resistant (MDR) pathogenic bacteria is a major threat to global health. Recently, the Centers for Disease Control and Prevention reported possibilities of greater deaths due to bacterial infections than cancer. Nanomaterials, especially small-sized (size ≤10 nm) silver nanoparticles (AgNPs), can be employed to combat these deadly bacterial diseases. However, high reactivity, instability, susceptibility to fast oxidation, and cytotoxicity remain crucial shortcomings for their uptake and clinical application. In this review, we discuss various AgNPs-based approaches to eradicate bacterial infections and provide comprehensive mechanistic insights and recent advances in antibacterial activity, antibiofilm activity, and cytotoxicity (both in vitro and in vivo) of AgNPs. The mechanistic of antimicrobial activity involves four steps: (i) adhesion of AgNPs to cell wall/membrane and its disruption; (ii) intracellular penetration and damage; (iii) oxidative stress; and (iv) modulation of signal transduction pathways. Numerous factors affecting the bactericidal activity of AgNPs such as shape, size, crystallinity, pH, and surface coating/charge have also been described in detail. The review also sheds light on antimicrobial photodynamic therapy and the role of AgNPs versus Ag⁺ ions release in bactericidal activities. In addition, different methods of synthesis of AgNPs have been discussed in brief.

Detailed Kinetic and Mechanistic Study for the Preparation of Silver Nanoparticles by a Chemical Reduction Method in the Presence of a Neuroleptic Agent (Gabapentin) at an Alkaline pH and its Characterization

For the very first time, a detailed kinetic study for the preparation of silver nanoparticles (silver NPs) by neuroleptic agent gabapentin (GBP) in the absence of a stabilizer has been reported in this investigation. This paper is devoted to the preparation of silver nanoparticles by a chemical reduction method in which gabapentin acts as both a reductant and a stabilizer, and AgNO₃ is used as a source of Ag⁺ ions and NaOH for maintaining the alkaline medium. A UV-visible spectrophotometer is used to monitor the progress of the reaction kinetics in an aqueous medium by changing the concentration of different variables such as AgNO₃, NaOH, and gabapentin at 40 °C. It is found that the reaction rate follows a pseudo-first-order reaction. The thermodynamic activation parameters were also studied at five different temperatures (303, 308, 313, 318, and 323 K) and used in the support of the proposed mechanistic scheme for the formation of silver nanoparticles. The prepared silver nanoparticles were characterized using different techniques: UV-visible spectrophotometry, Fourier transform infrared spectroscopy, field emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, transmission electron microscopy, and powder X-ray diffraction. The average particle size was observed in the range of 5-45 nm.

Synthesis of nanomaterials using various top-down and bottom-up approaches, influencing factors, advantages, and disadvantages: A review

Nanotechnology is one of the emerging fields of the 21st Century. Many new devices and patentable technology is based on nanomaterials (NMs). One of the dominant factors in the use of nanomaterials and their applications in various fields is the synthesis and growth mechanism of nanostructures and nanomaterials. A nanostructured material may have been a good candidate in one application but could be more useful in a different application if synthesized by a different mechanism and technique. Similarly, the structure and morphology of a nanomaterial also depend upon the method of growth and synthesis. For example, it is easy to grow and synthesize amorphous nanostructured thin film using the plasma magnetron sputtering technique, but it may be difficult to obtain a similar structure using the thermal evaporation process due to the nature of the technique itself. In this study, the Top-down and Bottom-up methods and techniques of synthesizing nanostructured materials are reviewed, compared, and analyzed. Both approaches are critically analyzed, and the influencing factors on the synthesis of different nanomaterials, the advantages, and disadvantages of each technique are reported. This review also provides a step-by-step analysis of the choice of method for the synthesis of namomaterials for specific applications.

Silver Nanoparticles for Conductive Inks: From Synthesis and Ink Formulation to Their Use in Printing Technologies

Currently, silver nanoparticles have attracted large interest in the photonics, electrics, analytical, and antimicrobial/biocidal fields due to their excellent optical, electrical, biological, and antibacterial properties. The versatility in generating different sizes, shapes, and surface morphologies results in a wide range of applications of silver nanoparticles in various industrial and health-related areas. In industrial applications, silver nanoparticles are used to produce conductive inks, which allows the construction of electronic devices on low-cost and flexible substrates by using various printing techniques. In order to achieve successful printed patterns, the necessary formulation and synthesis need to be engineered to fulfil the printing technique requirements. Additional sintering processes are typically further required to remove the added polymers, which are used to produce the desired adherence, viscosity, and reliable performance. This contribution presents a review of the synthesis of silver nanoparticles via different methods (chemical, physical and biological methods) and the application of silver nanoparticles under the electrical field. Formulation of silver inks and formation of conductive patterns by using different printing techniques (inkjet printing, screen printing and aerosol jet printing) are presented. Post-printing treatments are also discussed. A summary concerning outlooks and perspectives is presented at the end of this review.

Synthesis, Characterization and Biomedical Application of Silver Nanoparticles

Silver nanoparticles (AgNPs) have been employed in various fields of biotechnology due to their proven properties as an antibacterial, antiviral and antifungal agent. AgNPs are generally synthesized through chemical, physical and biological approaches involving a myriad of methods. As each approach confers unique advantages and challenges, a trends analysis of literature for the AgNPs synthesis using different types of synthesis were also reviewed through a bibliometric approach. A sum of 10,278 publications were analyzed on the annual numbers of publication relating to AgNPs and biological, chemical or physical synthesis from 2010 to 2020 using Microsoft Excel applied to the Scopus publication database. Furthermore, another bibliometric clustering and mapping software were used to study the occurrences of author keywords on the biomedical applications of biosynthesized AgNPs and a total collection of 224 documents were found, sourced from articles, reviews, book chapters, conference papers and reviews. AgNPs provides an excellent, dependable, and effective solution for seven major concerns: as antibacterial, antiviral, anticancer, bone healing, bone cement, dental applications and wound healing. In recent years, AgNPs have been employed in biomedical sector due to their antibacterial, antiviral and anticancer properties. This review discussed on the types of synthesis, how AgNPs are characterized and their applications in biomedical field.

Magnesium Nanoparticle Synthesis from Powders via Pulsed Laser Ablation in Liquid for Nanocolloid Production

Magnesium nanoparticles of various mean diameters (53–239 nm) were synthesised in this study via pulsed laser ablation in liquid (PLAL) from millimetre sized magnesium powders within isopropyl alcohol. It was observed via a 3 × 3 full factorial design of experiments that the processing parameters can control the nanoparticle distribution to produce three size-distribution types (bimodal, skewed and normal). Ablation times of 2, 5, and 25 min where investigated. An ablation time of 2 min produced a bimodal distribution with the other types seen at higher periods of processing. Mg nanoparticle Ultraviolet–Visible spectroscopy (UV–Vis) absorbance at 204 nm increased linearly with increasing ablation time, indicating an increase in nanoparticle count. The colloidal density (mg/mL) generally increased with increasing nanoparticle mean diameter as noted via increasing UV–Vis absorbance. High laser scan speeds (within the studied range of 3000–3500 mm/s) tend to increase the nanoparticle count/yield. For the first time, the effect of scan speed on colloidal density, UV–Vis absorbance and nanoparticle diameter from metallic powder ablation was investigated and is reported herein. The nanoparticles formed dendritic structures after being drop cast on aluminium foil as observed via field emission scanning electron microscope analysis. Dynamic light scattering was used to measure the size of the nanoparticles. Magnesium nanoparticle inks show promise for use in the fabrication conductive tracks or thermal insulation in electronics.

Conditions adjustment of polycaprolactone nanofibers scaffolds encapsulated with core shells of Au@Se via laser ablation for wound healing applications

Au@Se core-shell nanoparticles were obtained via laser ablation technique to be incorporated into polycaprolactone (PCL) nanofibrous scaffolds for wound healing applications at different contributions of Se nanoparticles (SeNPs). The synthesized layers were inspected via X-ray diffraction (XRD) and Fourier transformed infrared (FTIR). Additionally, microstructural and surface morphology were followed with different SeNPs contributions before and after fibroblast culturing. Moreover, Selenium dopant is affected Maximum roughness valley depth while it starts from 0.31 µm at Au@0.0Se@PCL reaching 0.457 µm at Au@12Se@PCL; however, after culturing starts from 0.3833 µm reaching 0.41 µm. Besides, the antibacterial activity was screened, showing the absence of inhibition zones in free selenium composition; however, it grows up reaching 8.3 ± 0.8, and 8.0 ± 0.8 for E. coli and S. aureus, respectively at the maximum contribution of selenium. SeNPs contributed composites show higher cell viability than Selenium free composite that it reaches its max in Au@8.0Se@PCL, recording 95.3 ± 2.3%. Composites show an excellent Wound dressing capability that its performance is directly proportional to selenium content. This significant enrichment of antibacterial activity and cell viability could recommend these composites for additional research in medical applications.

The Recent Progress on Silver Nanoparticles: Synthesis and Electronic Applications

Nanoscience enables researchers to develop new and cost-effective nanomaterials for energy, healthcare, and medical applications. Silver nanoparticles (Ag NPs) are currently increasingly synthesized for their superior physicochemical and electronic properties. Good knowledge of these characteristics allows the development of applications in all sensitive and essential fields in the service of humans and the environment. This review aims to summarize the Ag NPs synthesis methods, properties, applications, and future challenges. Generally, Ag NPs can be synthesized using physical, chemical, and biological routes. Due to the great and increasing demand for metal and metal oxide nanoparticles, researchers have invented a new, environmentally friendly, inexpensive synthetic method that replaces other methods with many defects. Studies of Ag NPs have increased after clear and substantial support from governments to develop nanotechnology. Ag NPs are the most widely due to their various potent properties. Thus, this comprehensive review discusses the different synthesis procedures and electronic applications of Ag NPs.

The Action-Networks of Nanosilver: Bridging the Gap between Material and Biology

The emergence of nanosilver (silver in nanoscale shapes and their assemblies) benefits the landscape of modern healthcare; however, this brings about concerns over its safety issues associated with an ultrasmall size and high mobility. By reviewing previous reporting details about the synthesis and characterization of nanosilver and its biological responses, a gap between materials synthesis and their biomedical uses is characterized by the insufficient understanding of the interacting and interplaying nanoscale actions of silver. To improve reporting quality and advance clinical translations, it is suggested that researchers have a comprehensive recognition of the "Indications for use" before designing innovative nanosilver-based materials and an "Action-network" concept addressing the acting range and strength of those nanoscale actions is implemented. Although this discussion is specific to nanosilver, the idea of "Indications for use" centered design and synthesis is generally applicable to other biomedical nanomaterials.

Growth Kinetic Study of Tannic Acid Mediated Monodispersed Silver Nanoparticles Synthesized by Chemical Reduction Method and Its Characterization

The complex process of nanoparticle formation in an aqueous solution is governed by kinetics and thermodynamic factors. This paper describes a room-temperature growth kinetic study and evaluation of thermodynamic activation parameters of monodispersed silver nanoparticles (AgNPs) synthesized in alkaline medium by chemical reduction method using AgNO₃ as a source of Ag⁺ ions and tannic acid (TA) as a reductant (reducing agent) as well as a capping or stabilizing agent in the absence of any other external stabilizer. A simple and conveniently handled reaction process was monitored spectrophotometrically to study the growth kinetics in an aqueous solution as a function of the concentration of silver ion, hydroxide ion, and TA, respectively. The neutral nucleophilic group donates the electron density via a lone pair of electrons to Ag⁺ ions for the reduction process, i.e., for the nucleation of AgNPs colloid. Also, a few silver ions form a silver oxide, which also facilitates the nucleation center to enhance the growth of AgNPs colloid. The decrease and increase in rate constant on varying the TA concentration showed its adsorption onto the surface of metallic AgNPs and stabilized by polygalloyl units of TA and were the main elements to control the growth kinetics. Consequently, stabilized TA-mediated AgNPs are formed using the electron donated by quinone form of TA followed by a pseudo-first-order reaction. Apart from this, nanoparticles formed were characterized using UV-visible spectrophotometry, Fourier transform infrared spectroscopy, field emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, transmission electron microscopy, and powder X-ray diffraction techniques to confirm its formation during the present kinetic study.

A Review on Silver Nanoparticles: Classification, Various Methods of Synthesis, and Their Potential Roles in Biomedical Applications and Water Treatment

Recent developments in nanoscience have appreciably modified how diseases are prevented, diagnosed, and treated. Metal nanoparticles, specifically silver nanoparticles (AgNPs), are widely used in bioscience. From time to time, various synthetic methods for the synthesis of AgNPs are reported, i.e., physical, chemical, and photochemical ones. However, among these, most are expensive and not eco-friendly. The physicochemical parameters such as temperature, use of a dispersing agent, surfactant, and others greatly influence the quality and quantity of the synthesized NPs and ultimately affect the material’s properties. Scientists worldwide are trying to synthesize NPs and are devising methods that are easy to apply, eco-friendly, and economical. Among such strategies is the biogenic method, where plants are used as the source of reducing and capping agents. In this review, we intend to debate different strategies of AgNP synthesis. Although, different preparation strategies are in use to synthesize AgNPs such as electron irradiation, optical device ablation, chemical reduction, organic procedures, and photochemical methods. However, biogenic processes are preferably used, as they are environment-friendly and economical. The review covers a comprehensive discussion on the biological activities of AgNPs, such as antimicrobial, anticancer anti-inflammatory, and anti-angiogenic potentials of AgNPs. The use of AgNPs in water treatment and disinfection has also been discussed in detail.

Preparation of a multifunctional silver nanoparticles polylactic acid food packaging film using mango peel extract

As high-efficiency, safe, and low-drug resistant antibacterial agents, silver nanoparticles (AgNPs) have been widely applied in food and biomedicine. AgNPs was prepared using mango peel extract (MPE) as green and cheap reducing agent and stabilizer. In addition, a novel of preservative film material was developed with polylactic acid (PLA) as protective and substrate. AgNPs was characterized by XPS, XRD and TEM, and the size of AgNPs were in the range of 2.5-6.5 nm. The addition of AgNPs improved the mechanical properties of the film and its barrier ability to water vapor and oxygen. The film exhibited excellent antibacterial properties, and the inhibition rate against Escherichia coli and Staphylococcus aureus were above 95%. Furthermore, in terms of safety, the silver migration and cytotoxicity of the film met the relevant standards, and the shelf life of strawberries was significantly extended.

Size Control of Synthesized Silver Nanoparticles by Simultaneous Chemical Reduction and Laser Fragmentation in Origanum majorana Extract: Antibacterial Application

In this work, silver nanoparticles (Ag NPs) were synthesized using a chemical reduction approach and a pulsed laser fragmentation in liquid (PLFL) technique, simultaneously. A laser wavelength of 532 nm was focused on the as produced Ag NPs, suspended in an Origanum majorana extract solution, with the aim of controlling their size. The effect of liquid medium concentration and irradiation time on the properties of the fabricated NPs was studied. While the X-ray diffraction (XRD) pattern confirmed the existence of Ag NPs, the UV–Vis spectrophotometry showed a significant absorption peak at about 420 nm, which is attributed to the characteristic surface plasmon resonance (SPR) peak of the obtained Ag NPs. By increasing the irradiation time and the Origanum majora extract concentration, the SPR peak shifted toward a shorter wavelength. This shift indicates a reduction in the NPs’ size. The effect of PLFL on size reduction was clearly revealed from the transmission electron microscopy images. The PLFL technique, depending on experimental parameters, reduced the size of the obtained Ag NPs to less than 10 nm. The mean zeta potential of the fabricated Ag NPs was found to be greater than −30 mV, signifying their stability. The Ag NPs were also found to effectively inhibit bacterial activity. The PLFL technique has proved to be a powerful method for controlling the size of NPs when it is simultaneously associated with a chemical reduction process.

Preparation and Characterization of Nanofibrous Scaffolds of Ag/Vanadate Hydroxyapatite Encapsulated into Polycaprolactone: Morphology, Mechanical, and In Vitro Cells Adhesion

Series of nanofibrous composites of polycaprolactone (PCL) were fabricated in different compositions of modified hydroxyapatite (HAP). The encapsulated HAP was co-doped with Ag/vanadate ions at different Ag contributions. XRD and FTIR techniques confirmed the powder and fibrous phase formation. Further, the morphological and mechanical behaviors of the electrospun nanofibrous scaffolds containing hydroxyapatite were investigated. The nanofibrous phases were biologically evaluated via studying contact angle, antibacterial, cell viability, and in vitro growth of human fibroblasts cell line (HFB4). It is obvious that silver ions cause gradual deviation in powder grains from wafer-like to cloudy grains. The maximum height of the roughness (Rt) ranged from 902.0 to 956.9 nm, while the valley depth of the roughness (Rv) ranged from 308.3 to 442.8 nm, for the lowest and the highest additional Ag ions for powdered phases. Moreover, the highest contribution of silver through the nanofibrous phases leads to the formation of lowest filaments size ranged from 0.07 to 0.53 µm. Further, the fracture strength was increased exponentially from 2.51 ± 0.35 MPa at zero concentration of silver ions up to 4.23 ± 0.64 MPa at 0.6 Ag/V-HAP@PCL. The fibrous phases were biologically evaluated in terms of antibacterial, cell viability, and in vitro growth of human fibroblasts cell line (HFB4). The nanofibrous composition of 0.8 Ag/V-HAP@PCL reached the maximum potential against E. coli and S. aureus and recorded 20.3 ± 1.1 and 19.8 ± 1.2 mm, respectively. This significant performance of the antibacterial activity and cell viability of co-doped HAP distributed through PCL could recommend these compositions for more research in biological applications, including wound healing.

Green synthesis, characterization and applications of silver nanoparticle mediated by the aqueous extract of red onion peel

This manuscript describes the reuse of biowaste for the biosynthesis of silver nanoparticles (AgNPs) and their applications. In particular, we hypothesized that the phytochemicals in the onion peels could act as reductant for silver nanoparticles syntheses. AgNO₃ solution (1 mmol) was added dropwise to an aqueous solution of onion peel extract in 3:7 ratio. The reaction mixture was subjected to heating at 90 °C for about 30 min. During the synthesis of the AgNPs, the change of the colour of solution was observed. The AgNPs solution was centrifuged to obtain the two layers, which consists of clear solution and solid layers at 12000 rpm for 30 min. The precipitate was filtered and was re-dispersed in deionised water (25 mL). The solution was centrifuged again to obtain the purified AgNPs. Subsequently, this solution was freeze dried for 48 h to afford the powdered AgNPs. In this work, the structure of the AgNPs were synthesized in spherical shape, with an average size of 12.5 nm observed in the Transmission electron microscopy (TEM) analysis. For catalytic application, the synthesized AgNPs could be applied as green catalyst to promote Knoevenagel and Hantzsch reactions. In most cases, the desired products were obtained in satisfactory yields. In addition, the AgNPs were found to be recyclable for the subsequent reactions. After five successive runs, the average isolated yields for both transformations were recorded to be 91% (Knoevenagel condensation) and 94% (Hantzsch reaction), which indicated that the existing AgNPs could apply as green catalyst in the field of organic synthesis. Furthermore, the AgNPs also showed satisfactory result in antioxidant activity. The current results indicate that the AgNPs can act as alternative antioxidant agent and green catalyst in mediating organic transformations.

A critical review on quantum dots: From synthesis toward applications in electrochemical biosensors for determination of disease-related biomolecules

Fluorescent quantum dots (QDs), defined by a diameter size of <10 nm, have been the core concept of nanoscience and nanotechnology since their inception. QDs possess many unique structural, electrochemical and photochemical properties that render them a promising platform for sensing applications. These nanomaterials can greatly enhance the analytical performances of biosensors, namely detection limit, sensitivity and selectivity. QDs are being developed not only because of their ability for signal enhancement but also because of their high capacity for fuctionalization with bioreceptors. In this review, we summarize a basic knowledge of QDs before focusing on their application to sensing thus far followed by a discussion of future directions for research into the sensing field. Due to the nature of QDs, especially their ability to combine nanotechnology and biotechnology, they possess the potential to open a novel paradigm on early diagnosis of diseases using the electrochemical biosensors. Therefore, we try to give a comprehensive view of the role of these zero-dimensional (0D) nanomaterials in the designing electrochemical sensors for determination of disease-related biomolecules, including tumor markers, inflammatory biomarkers, depression markers and archetypal biomarker in diabetes diagnosis. Considering the high potential of QDs for the electrochemistry-based biosensing strategies, the authors suggest that more research is needed on understanding their electronic properties and why synthesis and surface modification methods can affect these properties.

Modular and Integrated Systems for Nanoparticle and Microparticle Synthesis-A Review

Nanoparticles (NPs) and microparticles (MPs) have been widely used in different areas of research such as materials science, energy, and biotechnology. On-demand synthesis of NPs and MPs with desired chemical and physical properties is essential for different applications. However, most of the conventional methods for producing NPs/MPs require bulky and expensive equipment, which occupies large space and generally need complex operation with dedicated expertise and labour. These limitations hinder inexperienced researchers to harness the advantages of NPs and MPs in their fields of research. When problems individual researchers accumulate, the overall interdisciplinary innovations for unleashing a wider range of directions are undermined. In recent years, modular and integrated systems are developed for resolving the ongoing dilemma. In this review, we focus on the development of modular and integrated systems that assist the production of NPs and MPs. We categorise these systems into two major groups: systems for the synthesis of (1) NPs and (2) MPs; systems for producing NPs are further divided into two sections based on top-down and bottom-up approaches. The mechanisms of each synthesis method are explained, and the properties of produced NPs/MPs are compared. Finally, we discuss existing challenges and outline the potentials for the development of modular and integrated systems.

The Potential of Silver Nanoparticles for Antiviral and Antibacterial Applications: A Mechanism of Action

Rapid development of nanotechnology has been in high demand, especially for silver nanoparticles (AgNPs) since they have been proven to be useful in various fields such as medicine, textiles, and household appliances. AgNPs are very important because of their unique physicochemical and antimicrobial properties, with a myriad of activities that are applicable in various fields, including wound care management. This review aimed to elucidate the underlying mechanisms of AgNPs that are responsible for their antiviral properties and their antibacterial activity towards the microorganisms. AgNPs can be synthesized through three different methods-physical, chemical, and biological synthesis-as indicated in this review. The applications and limitations of the AgNPs such as their cytotoxicity towards humans and the environment, will be discussed. Based on the literature search obtained, the properties of AgNPs scrutinizing the antibacterial or antiviral effect shown different interaction towards bacteria which dependent on the synthesis processes followed by the morphological structure of AgNPs.