An exclusive deposition method of silver nanoparticles on TiO2 particles via low-temperature decomposition of silver-alkyldiamine complexes in aqueous media

The low-temperature decomposition of Ag(i)–dmpda complexes catalytically occurs on TiO₂ surfaces in water.

Super Stability of Ag Nanoparticle in Crystalline Lamellar (Lc) Liquid Crystal Matrix at Different pH Environment

The symmetry concept in this paper is related to the natural self-assembly of noble metal nanoparticles in the long range periodic structure of liquid crystal (LC). The current study deliberates the effect of pH on the stability of nanoparticles (NPs) in the lamellar phase of a lyotropic LC environment. The LC was prepared by the mass ratio 0.33:0.22:0.45 for (HDTABr):1-pentanol:water. The LC containing silver nanoparticles (AgNPs) was prepared by replacing the water with Ag solution. The AgNPs were produced by the in situ preparation method in LC. The solution of AgNPs-LC was varied at different pH. The absorption intensities were determined by using ultra-violet spectroscopy (UV-vis). The surface potential and hydrodynamic particle size were determined by using Zeta-potential (measurements). The surface enhanced Raman spectroscopy (SERS) was carried out to enhance the Raman signals of 4-aminobenzenethiol (4-ABT) deposited onto AgNPs as substrate. It is found that all characterizations exhibited super stability for AgNPs dispersed in LC at pH = 3 to 12 with the optimum stability at pH = 5–6. The remarkable stability of NPs is an important indicator of the various applications in nanotechnology and nanoscience fields.

Plasmon-Induced Dimerization of Thiazolidine-2,4-dione on Silver Nanoparticles: Revealed by Surface-Enhanced Raman Scattering Study

Surface-enhanced Raman scattering (SERS) study carried on thiazolidine-2,4-dione (TZD), a pharmacologically active heterocyclic compound, points to the presence of TZD dimer formed by plasmon-induced dimerization reaction of TZD on the surface of silver nanoparticles (Ag NP) at TZD concentrations of 10^-3 M and above. The evidence for the presence of dimer was obtained from the appearance of a prominent band at 1566 cm^-1 corresponding to the ν(C═C) band (a characteristic vibrational band observed for the Knoevenagel condensation reaction products) which is absent in the normal Raman scattering (NRS) spectra of TZD solid/solution. The observed spectrum compares well with the calculated spectrum of dimer obtained using density functional theory (DFT) calculations. The dimerization reaction is plausibly induced by the transfer of hot electrons generated by the nonradiative plasmon decay of Ag NP, and the proposed reaction mechanism is discussed. However, at lower concentrations (10^-4-10^-6 M), the characteristic dimer peak (1566 cm^-1) is absent and the SERS spectra resemble more the NRS spectrum of TZD with a few changes. The spectral analysis supported by DFT calculations showed that TZD molecules undergo deprotonation and get adsorbed on the Ag NP surface as enolate forms. The proximity of TZD molecules on the surface of Ag NP is a necessary factor for the dimerization to occur. At lower concentrations, most molecules lie apart and reactions between molecules become less feasible, and they remain as monomers on the surface, while at higher concentrations the molecules are closer to each other on the Ag NP surface favoring the dimerization reaction to take place, leading to the formation of the dimer.

Facile green synthesis and applications of silver nanoparticles: a state-of-the-art review

In the field of nanotechnology, the development of reliable and eco-friendly methods for the synthesis of NPs is crucial. The conventional methods for the synthesis of NPs are costly, toxic, and not ecofriendly. To overcome these issues, natural sources such as plant, bacteria, fungi, and biopolymers have been used to synthesize AgNPs. These natural sources act as reducing and capping agents. The shape, size, and applications of AgNPs are prominently affected by the reaction parameters under which they are synthesized. Accessible distributed data on the synthesis of AgNPs include the impact of different parameters (temperature and pH), characterization techniques (DLS, UV-vis, FTIR, XRD, SEM, TEM and EDX), properties and their applications. This review paper discusses all the natural sources such as plants, bacteria, fungi, and biopolymers that have been used for the synthesis of AgNPs in the last ten years. AgNPs synthesized by green methods have found potential applications in a wide spectrum of areas including drug delivery, DNA analysis and gene therapy, cancer treatment, antimicrobial agents, biosensors, catalysis, SERS and magnetic resonance imaging (MRI). The current limitations and future prospects for the synthesis of inorganic nanoparticles by green methods are also discussed herein.

Reduction of nitroarenes catalyzed by microgel-stabilized silver nanoparticles

Poly(N-isopropylacrylamide-co-acrylamide) (PNA-BIS-2) microgels were synthesized by free radical precipitation polymerization in aqueous medium. Spherical Ag nanoparticles with diameter of 10-20 nm were fabricated inside the PNA-BIS-2 microgels by in-situ reduction of silver nitrate using sodium borohydride as reducing agent. The Ag nanoparticles- loaded hybrid microgels were characterized by Scanning electron microscopy (SEM), Transmission electron microscopy (TEM), Energy dispersive X-ray (EDX), Scanning transmission electron microscopy (STEM), Ultraviolet visible spectroscopy (UV Visible), Thermogravimetric analysis (TGA) and X-ray diffraction (XRD). Ag contents in the hybrid system were determined by inductively coupled plasma - optical emission spectrometry (ICP-OES). Various nitroarenes were successfully converted into their respective aromatic amines with good to excellent yields (ranging from 75% to 97%) under mild reaction conditions. The catalyst has ability to successfully convert substituted nitroarenes into desired products keeping many functionalities intact. The catalyst can be stored for long time without any sign of aggregation and can be used multiple times without any significant loss in its catalytic activity.

Activation of atomically precise silver clusters on carbon supports for styrene oxidation reactions

Metal clusters have distinct features such as large surface area, low-coordination-atom enriched surfaces, and discrete energy levels that influence their behavior during catalytic reactions. Atomically-precise Ag clusters, which are analogues of more well-studied Au clusters, are yet to be fully explored as catalysts for various chemical reactions. 2,4-Dimethylbenzenethiol-protected Ag25 clusters were prepared and deposited onto carbon supports followed by calcination. Results from X-ray absorption fine structure (EXAFS) spectroscopy measurements and other characterization techniques indicated that thermal activation of carbon-supported Ag25 clusters resulted in dethiolation of Ag clusters at 250 °C and beyond, and consequently mild growth in particle sizes of Ag clusters on carbon supports was seen with increasing activation temperatures. Both as-prepared and activated Ag25 clusters were active for styrene oxidation reactions, with high selectivity towards styrene oxide, without using any promoter. Results show that mild activation at 250 °C yields the most active catalysts, and higher activation temperatures lead to decreased activities and slightly poorer selectivity to styrene oxidation as a result of cluster sintering. EXAFS data shows the resulting activated clusters are composed of Ag metal and that all thiols are removed from the Ag cluster surfaces, though XPS data shows that thiol oxidation products are still present in the sample.

Selective Aerobic Oxidation of Benzylic Alcohols Catalyzed by a Dicyclopropenylidene-Ag(I) Complex

The unprecedented synthesis, single-crystal X-ray structure, and first catalytic application of a dicarbene-Ag(I) complex [Ag(BAC)₂][CO₂CF₃] (BAC = bis(diisopropyl)aminocyclopropenylidene) is reported. This novel complex provides a versatile catalytic platform for selective aerobic oxidation of benzylic alcohols to aldehyde or ketone products in high yields. Ease of experimental execution coupled with the use of abundant atmospheric molecular oxygen as an oxidant and low catalyst loading are inherit strengths of these oxidations.

Ag-Based nanocomposites: synthesis and applications in catalysis

Ag-Based nanocomposites, including supported Ag nanocomposites and bimetallic Ag nanocomposites, have been intensively investigated as highly efficient catalysts because of their high activity and stability, easy preparation, low cost, and low toxicity. Herein, we systematically summarize and comprehensively evaluate versatile synthetic strategies for the preparation of Ag-based nanocomposites, and outline their recent advances in catalytic oxidation, catalytic reduction, photocatalysis and electrocatalysis. In addition, the challenges and prospects related to Ag-based nanocomposites for various catalytic applications are also discussed. In light of the most recent advances in Ag-based nanocomposites for catalysis applications, this review provides a comprehensive assessment on the material selection, synthesis and catalytic characteristics of these catalysts, which offers a strategic guide to build a close connection between Ag nanocomposites and catalysis applications.

Ag-Nanoparticle-Bearing Poly(vinylidene fluoride) Nanofiber Mats as Janus Filters for Catalysis and Separation

Hydrophilic Ag nanoparticles were pattern-deposited onto one side of an electrospun poly(vinylidene fluoride) (PVDF) nanofiber mat, yielding a Janus filter. The filter was used to separate a receiver cell from a reactor cell that contained an aqueous 4-nitrophenol/NaBH₄ solution. Upon contact with this solution, the Ag nanoparticles catalyzed the reduction of 4-nitrophenol to 4-aminophenol. After the reaction reached completion, ethyl acetate was added into the reactor to extract the product. During this process, the ethyl acetate containing 4-aminophenol also selectively permeated regions of the hydrophobic yet oleophilic PVDF mat that were not covered by Ag nanoparticles. The product was obtained after the evaporation of ethyl acetate. This paper demonstrates the first use of a Janus filter in a catalytic separatory reactor that catalyzes a chemical reaction and then facilitates the eventual separation of the formed product via filtration.

Synthesis and Characterization of Gold-Silver Nanoparticles in Deionized Water by Pulsed Laser Ablation (PLAL) Technique at Different Laser Parameter

Gold and silver nanoparticles (NPs) are physically synthesized using Q-switched neodymium-doped yttrium aluminum garnet (Nd:YAG)-pulsed laser ablation in liquid (PLAL) technique which is a rapid, simple and efficient one-step synthesis. The gold and silver colloidal solutions are separately prepared by 1064[Formula: see text]nm of pulsed laser ablation of metallic target (gold and silver) which is immersed in deionized water. Ultraviolet–visible spectroscopy (UV–Vis) analysis shows the absorption band of gold and silver NPs at [Formula: see text][Formula: see text]nm and [Formula: see text][Formula: see text]nm, respectively. The absorption spectra and color variations of gold and silver NPs at three different laser parameters (output laser energies, target distances from focal point and laser time exposures). High-resolution transmission electron microscopy shows the spherical shape of gold and silver NPs with 34[Formula: see text]nm and 33[Formula: see text]nm diameter of size, respectively, are reported. The aggregation and particle sizes of gold and silver NPs due to minimum energy (75[Formula: see text]mJ) and maximum energy (311[Formula: see text]mJ) are observed.

Structural evolution of Ag/BN hybrids via a polyol-assisted fabrication process and their catalytic activity in CO oxidation

Enhanced catalytic activity of Ag/BN nanohybrids is ascribed to the formation of a thin intermediate Ag–O–B layer.

Catalytic use of layered materials for fine chemical syntheses

The present work reviews the catalytic use of layered solid materials for fine chemical syntheses with focus on layered double hydroxides, but including other classes of layered compounds of catalytic relevance.

Silver Nanoparticles: Synthesis and Applications

Nanotechnology involves the production, manipulation, and use of materials ranging in size from less than a micron to that of individual atoms, is an emerging field of modern science, and utilizes nanoscaled systems. Nanoparticles (NPs) are being viewed as fundamental building blocks of nanotechnology. Although nanomaterials may be synthesized using chemical approaches, it is now possible to include the use of biological systems such as bacteria, fungi, and plants. Currently, silver nanoparticles have shown great importance due to its large surface ratio and unique properties with myriad activities applicable in a number of applied sectors including microbial resistant applications (antibacterial/antifungal/anticancer/antiviral), water treatment, protective dressings, catalysis, and optical devices. This chapter encompasses the fabrication methods and dispersed applications of silver nanoparticles.

Efficient reduction of 4-nitrophenol catalyzed by 4-carbo-methoxypyrrolidone modified PAMAM dendrimer–silver nanocomposites

Ag–PPDNCs prepared with 4-carbomethoxypyrrolidone modified PAMAM showed very high activity in the reduction of 4-nitrophenol.

Application of Silver Nanoparticles in the Multicomponent Reaction Domain: A Combined Catalytic Reduction Methodology to Efficiently Access Potential Hypertension or Inflammation Inhibitors

The catalytic efficacy of silver nanoparticles was investigated toward the chemoselective reduction of nitro-tetrazole or amino acid-substituted derivatives into the corresponding amines in high isolated yields. This highly efficient protocol was thereafter applied toward the multicomponent reaction synthesis of heterocyclic dihydroquinoxalin-2-ones with high isolated yields. The reaction proceeds with low catalyst loading (0.8-1.4 mol %) and under mild catalytic conditions, a very good functional-group tolerance, and high yields and can be easily scaled up to more than 1 mmol of product. Thus, the present catalytic methodology highlights a useful synthetic application. Different molecules are designed and accordingly synthesized with the current protocol that could play the role of inhibitors of the soluble epoxide hydrolase, an important target for therapies against hypertension or inflammation.

From biotechnology principles to functional and low-cost metallic bionanocatalysts

Chemical, physical and mechanical methods of nanomaterial preparation are still regarded as mainstream methods, and the scientific community continues to search for new ways of nanomaterial preparation. The major objective of this review is to highlight the advantages of using green chemistry and bionanotechnology in the preparation of functional low-cost catalysts. Bionanotechnology employs biological principles and processes connected with bio-phase participation in both design and development of nano-structures and nano-materials, and the biosynthesis of metallic nanoparticles is becoming even more popular due to; (i) economic and ecologic effectiveness, (ii) simple one-step nanoparticle formation, stabilisation and biomass support and (iii) the possibility of bio-waste valorisation. Although it is quite difficult to determine the precise mechanisms in particular biosynthesis and research is performed with some risk in all trial and error experiments, there is also the incentive of understanding the exact mechanisms involved. This enables further optimisation of bionanoparticle preparation and increases their application potential. Moreover, it is very important in bionanotechnological procedures to ensure repeatability of the methods related to the recognised reaction mechanisms. This review, therefore, summarises the current state of nanoparticle biosynthesis. It then demonstrates the application of biosynthesised metallic nanoparticles in heterogeneous catalysis by identifying the many examples where bionanocatalysts have been successfully applied in model reactions. These describe the degradation of organic dyes, the reduction of aromatic nitro compounds, dehalogenation of chlorinated aromatic compounds, reduction of Cr(VI) and the synthesis of important commercial chemicals. To ensure sustainability, it is important to focus on nanomaterials that are capable of maintaining the important green chemistry principles directly from design inception to ultimate application.

Loading across the Periodic Table: Introducing 14 Different Metal Ions To Enhance Metal-Organic Framework Performance

Loading metal guests within metal-organic frameworks (MOFs) via secondary functional groups is a promising route for introducing or enhancing MOF performance in various applications. In this work, 14 metal ions (Li⁺, Na⁺, K⁺, Mg²⁺, Ca²⁺, Ba²⁺, Zn²⁺, Co²⁺, Mn²⁺, Ag⁺, Cd²⁺, La³⁺, In³⁺, and Pb²⁺) have been successfully introduced within the MIL-121 MOF using a cost-efficient route involving free carboxylic groups on the linker. The local and long-range structure of the metal-loaded MOFs is characterized using multinuclear solid-state NMR and X-ray diffraction methods. Li/Mg/Ca-loaded MIL-121 and Ag nanoparticle-loaded MIL-121 exhibit enhanced H₂ and CO₂ adsorption; Ag nanoparticle-loaded MIL-121 also demonstrates remarkable catalytic activity in the reduction of 4-nitrophenol.

Studies of surface of metal nanoparticles in a flowing liquid with XPS

Studying surface of catalyst nanoparticles in a flowing liquid is important for understanding the underlying mechanism of a reaction performed in liquid. We report the design of a reaction cell system of Si3N4 window covering the flowing liquid with an electron-transmissible membrane. By using metal nanoparticles as a catalyst dispersed in a solvent, examination of the surface of catalyst nanoparticles in a flowing liquid was demonstrated by observation of Ag 3d photoemission feature when a liquid containing Ag nanoparticles was flowing through this system.

Thermosensitive Behavior and Super-Antibacterial Properties of Cotton Fabrics Modified with a Sercin-NIPAAm-AgNPs Interpenetrating Polymer Network Hydrogel

Poly(N-isopropylacrylamide) (PNIPAAm), sericin (SS), and silver nitrate were combined to prepare an interpenetrating network (IPN) hydrogel having dual functions of temperature sensitivity and antibacterial properties. The structure and size of AgNPs in such an IPN hydrogel were characterized by the Fourier Transform Infrared spectrum (FT-IR), X-ray powder diffraction (XRD) and Transmission Electron Microscope (TEM), and the thermal properties of the IPN hydrogel were characterized by Differential Scanning Calorimetry (DSC). Based on XRD patterns, Ag⁺ was successfully reduced to Ag⁰ by SS. It was observed by TEM that the particle size of silver particles was lower than 100 nm. The glass transition temperature (Tg) of IPN hydrogel was better than that of the PNIPAAm/AgNPs hydrogels, and lower critical solution temperature (LCST) values of the IPN hydrogel were obtained by DSC i.e. 31 °C. The thermal stability of the IPN hydrogel was successfully determined by the TGA. This IPN hydrogel was then used to modify the cotton fabrics by the "impregnation" method using glutaraldehyde (GA) as the cross-linking agent. The structures and properties of IPN hydrogel modified cotton fabric were characterized by scanning electron microscopy (SEM), FT-IR, and the thermogravimetry analysis (TGA). The results show that NIPAAm was successfully polymerized into PNIPAAm, and that there were neglected new groups in the hydrogel IPN. The IPN hydrogel was then successfully grafted onto cotton fabrics. SEM observations showed that the IPN hydrogel formed a membrane structure between the fibers, and improved the compactness of the fibers. At the temperature close to LCST (≈31 °C), the entire system was easily able to absorb water molecules. However, the hydrophilicity tended to decrease when the temperature was higher or lower than the LCST. The antibacterial rates of the modified cotton fabric against S. aureus and E. coli were as high as 99%.

Self-catalyzed copper-silver complex inks for low-cost fabrication of highly oxidation-resistant and conductive copper-silver hybrid tracks at a low temperature below 100 °C

Cu-Ag complex inks are developed for printing conductive tracks of low cost, high stability, and high conductivity on heat-sensitive substrates such as polyethylene terephthalate (PET) substrates. The inks show an obvious self-catalyzed characteristic due to the in situ formation of fresh metal nanoparticles which promote rapid decomposition and sintering of the inks at a low temperature below 100 °C. The temperature is 40-60 °C lower than those of general Cu complex inks and 100-120 °C lower than those of general Cu/Ag particle inks. Highly conductive Cu-Ag tracks of 2.80 × 10^-5 Ω cm and 6.40 × 10^-5 Ω cm have been easily realized at 100 °C and 80 °C, respectively. In addition, the printed Cu-based tracks not only show high oxidation resistance at high temperatures of up to 140 °C (the maximum tolerable temperature of current PET substrate) but also show excellent stability at high humidity of 85% because of the very uniform Cu-Ag hybrid structure. The printable tracks exhibit great potential application in various wearable devices fabricated on textiles, papers, and other heat-sensitive substrates.

Sustainable Catalytic Activity of Ag-Coated Chitosan-Capped γ-Fe2O3 Superparamagnetic Binary Nanohybrids (Ag-γ-Fe2O3@CS) for the Reduction of Environmentally Hazardous Dyes-A Kinetic Study of the Operating Mechanism Analyzing Methyl Orange Reduction

The formation of binary nanohybrids consisting of environmentally benign components, γ-Fe₂O₃, chitosan (CS), and Ag (Ag-γ-Fe₂O₃@CS) (CSIOAg), containing very low concentration of Ag NPs (≤1.2 μM), has been reported. In the as-synthesized nanohybrids, the presence of γ-Fe₂O₃ (8.5 ± 0.8 nm) and Ag (5.9 ± 0.5 nm) are revealed by optical, XRD, TEM, and XPS analyses, and their presence in cubic phase is determined by XRD and SAED measurements. The catalytic activity of CSIOAg has been analyzed by performing the reduction of certain toxic dyes. Under all kinetic conditions, the reaction is attended by an induction period, which is reduced upon increasing [Ag] and [Dye] in a specific concentration range, as well as temperature, suggesting restructuring of the surface prior to reduction. In case of methyl orange (MO), the reduction results in its cleavage to produce N,N-dimethyl-1,4-phenylenediamine and sodium sulfanilate in a significantly higher (>97%) yield in a bimolecular reaction between MO and BH₄ ^-. The duration of induction period is regularly decreased and the rate of reduction (k _app) increases linearly with increasing Ag in the wide concentration range (0.03-2.4 μM). The reduction takes place with a second-order rate constant of 2.7 × 10⁴ dm³ mol^-1 s^-1, which is >3.5-fold higher than that in the absence of chitosan (IOAg) under identical experimental conditions. The kinetics of reduction of MO is controlled by the nature and extent of its adsorption on the catalyst surface. The weaker binding between MO and Ag catalyst only allows its effective reduction. The XPS analysis of CSIOAg and IOAg containing the same amount of Ag (1.2 μM) showed its higher amount on the surface of CSIOAg (0.12%) as compared to that of IOAg (0.09%). Detailed kinetic analysis of MO reduction, performed under pseudo-kinetic conditions for both the nanohybrids revealed them to follow Langmuir-Hinshelwood kinetic model and exhibited the recyclability up to 10 cycles with fairly high reaction efficiency and TOF, suggesting it to be a sustainable green nanosystem.

Formation of hierarchically-ordered nanoporous silver foam and its electrocatalytic properties in reductive dehalogenation of organic compounds

Nanostructuring of silver notably improved its electrocatalytic activity in reductive dehalogenation of a variety of aryl and alkyl bromides.

Synthesis of symmetrical and unsymmetrical tellurides via silver catalysis

The cross-coupling reaction of diaryl ditellurides with aryl boronic acids is described using AgNO₃ as a catalyst.

Continuous synthesis of tuneable sized silver nanoparticles via a tandem seed-mediated method in coiled flow inverter reactors

Size control of metal nanoparticles is essential to achieve accurate adjustment of their unique chemical and physical properties.

A mineralogically-inspired silver–bismuth hybrid material: an efficient heterogeneous catalyst for the direct synthesis of nitriles from terminal alkynes

A silver-containing hybrid material is reported as an effective heterogeneous catalyst for the direct synthesis of organic nitriles from terminal alkynes.

Evaluation of local anesthetic effects of Lidocaine-Ibuprofen ionic liquid stabilized silver nanoparticles in Male Swiss mice

A simple approach for the synthesis of Lidocaine-Ibuprofen ionic liquid stabilized silver nanoparticles (IL-AgNPs) was reported in this work. The shape, size and surface morphology of the Lidocaine-Ibuprofen ionic liquid stabilized AgNPs were characterized by using spectroscopic and microscopic techniques such as Ultraviolet-visible spectroscopy (UV-Visible), X-ray diffraction (XRD) analysis, Selected area electron diffraction (SAED), Transmission electron microscopy (TEM). TEM analysis showed the formation of 20-30nm size of IL-AgNPs with very clear lattice fringes. SAED pattern confirmed the highly crystalline nature of fabricated IL stabilized AgNPs. EDS results confirmed the formation of nanosilver. The fabricated IL-AgNPs were studied for their local anesthetic effect in rats. The results of local anesthetic effect showed that the time for onset of action by IL-AgNPs is 10min, which is significantly higher than that for EMLA. Further, tactile test results confirmed the stronger and faster local anesthetic effect of IL-AgNPs when compared to that of EMLA.

Atmospheric pulsed laser deposition and thermal annealing of plasmonic silver nanoparticle films

A new method for pulsed laser deposition of plasmonic silver nanoparticle (NP) films in flowing gas at atmospheric pressure is described. The ablation was done using an excimer laser at 248 nm. Fast optical imaging shows that the ablation plume is captured by the flowing gas, and is expected to form a NP aerosol, which is carried 5-20 mm to the substrate. The dependence of the deposition rate on laser fluence, gas flow velocity, and target-substrate distance was investigated using electron microscopy and absorption spectroscopy of the deposited films. The NP films were annealed in argon and hydrogen at 400 °C, and in air for temperatures in the range 200 °C-900 °C, leading to strong enhancement, and narrowing of the surface plasmon resonance. The films were used for surface enhanced Raman spectroscopy of a 10^-5 molar solution of Rhodamine 6G; films annealed in air at 400 °C were five times more sensitive than the as-deposited films.

Bio fabrication of silver nanoparticles as an effective wound healing agent in the wound care after anorectal surgery

Nowadays biological mediated syntheses of metal nanoparticles were utilized for various life caring applications. Our research group utilized Delonix elata leaf aqueous extract for the synthesis of silver nanoparticles. Further the synthesized silver nanoparticles were subjected for various characterization techniques which resulted in spherically agglomerated with biological components entrapped in it and also with average particle size of 36nm were studied and reported. Later the synthesized silver nanoparticles were subjected for wound healing property by size of measured lessions and body weight which results in better wound healing property were studied and discussed.

Silver Nanoparticles Stabilised by Cationic Gemini Surfactants with Variable Spacer Length

The present study is focused on the synthesis and investigation of the physicochemical and biological properties of silver nanoparticles stabilized with a series of cationic gemini surfactants having a polymethylene spacer of variable length. UV-VIS spectroscopy, dynamic light scattering, scanning electron microscopy and zeta potential measurements were applied to provide physicochemical characterization of the silver nanoparticles. The mean size values of the nanoparticles were found to be in the 50 to 115 nm range. From the nanoparticle size distributions and scanning electron microscopy images it results that a population of small nanoparticles with the size of several nanometers was confirmed if the nanoparticles were stabilized with gemini molecules with either a short methylene spacer (two or four −CH₂− groups) or a long spacer (12 −CH₂− groups). The average zeta potential value for silver nanoparticles stabilized with gemini molecules is roughly independent of gemini surfactant spacer length and is approx. +58 mV. An interaction model between silver nanoparticles and gemini molecules which reflects the gained experimental data, is suggested. Microbicidal activity determinations revealed that the silver nanoparticles stabilized with gemini surfactants are more efficient against Gram-negative bacteria and yeasts, which has a direct relation to the interaction mechanism of nanoparticles with the bacterial cell membrane and its structural composition.