Shape Of Silver Nanoparticles Research Articles

Label-Free Detection of DNA via Surface-Enhanced Raman Spectroscopy Using Au@Ag Nanoparticles.

DNA is a building block of life; surface-enhanced Raman spectroscopy (SERS) has been broadly applied in the detection of biomolecules but there are challenges in obtaining high-quality DNA SERS signals under non-destructive conditions. Here, we developed a novel label-free approach for DNA detection based on SERS, in which the Au@AgNPs core–shell structure was selected as the enhancement substrate, which not only solved the problem of the weak enhancement effect of gold nanoparticles but also overcame the disadvantage of the inhomogeneous shapes of silver nanoparticles, thereby improving the sensitivity and reproducibility of the SERS signals of DNA molecules. The method obtained SERS signals for four DNA bases (A, C, G, and T) without destroying the structure, then further detected and qualified different specific structures of DNA molecules. These results promote the application of SERS technology in the field of biomolecular detection.

Production, Characterization, and Cytotoxicity Effects of Silver Nanoparticles from Brown Alga (Cystoseira myrica)

A green, eco-friendly approach to biosynthesizing silver nanoparticles has been reported for marine macroalga (Cystoseira myrica) extract as a reducing agent. Different pH and temperature impact the green synthesis of silver nanoparticles suggesting that the synthesis depends greatly on pH and temperature. The structure and characters of synthesized nanoparticles were confirmed using HR-TEM, DLS, XRD, and FTIR. Cytotoxicity was indicated using provided cell lines of breast carcinoma cells (MCF-7) and human hepatocellular carcinoma cells (HepG2). Shape of silver nanoparticles at pH 9 and 75°C for 30 min was found to be suitable for the biosynthesis process and the AgNPs exhibited a characteristic absorption peak at 434 nm. High Resolution Electron Microscope Transmission reported polydisperse and spherical shapes ranging from 8 to 15 nm. High attractive and repulsive forces between each nanoparticle were recorded with an average zeta-potential value of approximately −29.3 mV. The X-ray diffraction study revealed the crystalline structure of silver nanoparticles. FTIR has shown the bioreduction of silver ions to silver nanoparticles through biomolecules found in algal extract. Silver nanoparticles have been found to have anticancer activity. The cytotoxicity assay was studied against MCF-7 and HepG2 at various concentrations (100, 50, 25, 12.5, 6.25, 3.125, 1.56, 0.78, 0.39, 0.2, and 0.1 μg/mL). By increasing the concentration of AgNPs from 0.1 to 100 μg/mL, the maximum percentage of viability against MCF-7 and HepG2 cell line decreased from 94.55 ± 7.55 to 19.879 ± 0.503 and from 78.56 ± 11.36 to 25.81 ± 2.66 after time exposure, respectively.

Microfluidic biochip platform sensitized by AgNPs for SERS based rapid detection of uric acid

Herein, a novel microfluidic-biochip enabled with surface enhanced Raman spectroscopy (SERS) as a readout has been demonstrated for uric acid (UA) detection as point-of care (POC) device. Three different biochip designs (D1, D2 and D3) containing pillars in a microchannel with different bending ratios were conceived and optimized for various mixing parameters using a multiphysics simulation tool. The microchannel, integrated with pillars, provide pressure perturbation, sharp corners, and variation in bending ratio improves phase shift and mixing index. Subsequently the microfluidic-biochips were fabricated by a combination of photo-and soft-lithography, and bonding strength between two Polydimethylsiloxane substrates were found stable up to a flow rate of 1.8 ml min−1. Further to realize SERS activity in the microfluidic-biochip, cubic shape silver nanoparticles (AgNPs), with an average size ∼68 nm, were synthesized using poly-ol method. The SERS activity was optimized by simultaneously flowing AgNPs and crystal violet (CV) dye of 10−6M, with double inlet in the reservoir and highest sensitivity was achieved in the D3 biochip. Further, D3 biochip was employed for detection of extended concentrations of CV and UA. The enhancement factor limit of detection and relative standard deviation was found to be 2 × 107, 8.9 × 10−11 and 2.7% respectively for CV and 3.1 × 103, 3.2 × 10−7 and 2.9% respectively for UA. Interference of UA with lactic acid has been tested and device was able to detect signature peaks of both biomarkers up to 50 × 10−9 M concentration. Thus, the developed microfluidic-biochip device has potential to be used in a POC setting for onsite detection of biomarkers.

In Vitro Activation of Ampicillin Effect with Plant Extract Cocktail-Mediated Silver Nanoparticles Against Multidrug-Resistant Bacteria Pathogens

Background: The emergence of antibiotic resistance and the continuing evolution of resistance even to newer drugs have always been a global challenge. In the pursuit of innovative solutions, there is growing interest in using nanomaterials with antibacterial potentials to combat this menace. Objectives: In this study, plant extract cocktail-mediated silver nanoparticles (PAgNPs) was used to stimulate the antibacterial effect of ampicillin (AMP) against multidrug-resistant (MDR) bacterial pathogens. Methods: The agar well diffusion technique was used to investigate the potentials of PAgNPs in activating the antibacterial activity of AMP in MDR bacteria, including Escherichia coli, Klebsiella pnuemoniae, Micrococcus luteus, and Clostridium difficile. Plant extract cocktail-mediated silver nanoparticles were synthesized by reacting 9 mL of 1 mM of silver nitrate with 0.5 mL each of Citrus limon juice and aqueous Newbouldia laevis extract under bright sunlight for 10 minutes. Plant extract cocktail-mediated silver nanoparticles were characterized using UV-visible spectroscopy (UV-Vis) and higher resolution transmission electron microscopy (HRTEM) with energy dispersive x-ray spectroscopy (EDS). Results: Plant extract cocktail-mediated silver nanoparticles colloidal solution was reddish-brown with a 441-nm surface plasmon resonance (SPR) absorption peak. The HRTEM micrograph showed the varied shaped silver nanoparticles (AgNPs) with the average size of 23.49 ± 10.49 nm. Similarly, EDS showed a strong typical metallic silver nanocrystallites absorption peak at 3.0 keV. The PAgNPs activate the AMP activity in MDR E. coli, M. luteus, K. pnuemoniae, and C. difficile. Conclusions: The present findings suggest that PAgNPs can be considered a suitable candidate for developing novel antibacterial drugs to combat the growing threat of antibiotic resistance.

Synthesis of silver nanoparticles (AgNPs) of leaves extract of Rhynchoglossum notonianum wall. for enhancing its bioavailability and antibacterial activity

Objective: Silver nanoparticles (AgNPs) derived from Rhynchoglossum notonianum Wall. leaf were the subject of this investigation to examine their synthesis, characterisation, and biological activity. Materials and Methods: Aqueous extracts of Rhynchoglossum notonianum Wall leaves and 0.1 M silver nitrate were used to make AgNPs. Particle size, Zeta potential, UV-Vis spectroscopy, and SEM were used to determine the AgNPs properties. Results: Rapid and homogeneous size and shape silver nanoparticles were synthesised utilising Rhynchoglossum notonianum Wall. extract. When methanolic leaf extracts of Rhynchoglossum notonianum Wall. were combined with an aqueous silver ion complex solution, the surface Plasmon vibrations were excited, resulting in the production of MERNAgNPs. UV-Visible spectroscopy was used to characterise the nanoparticles. The widening of the peak in the UV-visible spectrum suggested polydispersion. The silver nanoparticles in solution have a surface Plasmon band of 420nm. Aqueous silver nitrate solution is diffused throughout the reaction time, with no signs of agglomeration. The average particle size (z-average) was “132.6nm”, the polydispersity index was “0.248”, and the zeta values were -25.1mV with a 100% peak area. This implies a stable silver nanoparticle.

Green synthesis and standardization of Biologically Synthesized Silver Nanoparticles

The biological silver nanoparticle was synthesized extracellularly by using Musa balbisiana. The leaf extract has been used as reducing agent in the process of nanoparticles synthesis. In 50 ml leaf extract volume of AgNO3 stock solution was added to make finally the concentration as 1 mM of AgNO3 and allowed to shake in an incubator for several hours in the dark. The changed color was considered as the primary indication of nanoparticles formation. It was indicated that stable and 20-40nm roughly spherical shaped silver nanoparticles was formed. To standardize the nanoparticles biosynthesis different physical parameters like substrate concentration (0-8 mM), pH of range 5 to 12, temperature range of 5 to 500°C, incubation time range of 0 to 120 hrs and salinity of 0.1-1.0% were investigated. It was reported that 4mM AgNO3 conc, pH of 9, temperature 300°C, incubation time 72h and 0.2% salinity were found to be optimum for the synthesis and stability of the silver nanoparticles.

Excellent reversibility of resistive nanocomposite strain sensor composed of silver nanoflowers, polyurethane, and polyester rubber band

Wearable conductive nanocomposite strain sensors have received considerable attention for rehabilitation and human motion detection. However, their practical application has been hindered by the irreversible resistance change upon stretching cycles. Here we report a resistive-type conductive nanocomposite strain sensor with a nearly perfect reversibility (maximum strain = 30%). Flower shaped silver nanoparticles (AgNFs) with enhanced surface area construct a conductive network as a key sensing element in stretchable polyurethane (PU) matrix. Furthermore, polyester elastic rubber band (PB) is chosen as a backbone to ensure perfect mechanical elasticity and durability. A fiber-type strain sensor (PB/AgNF-PU sensor) is synthesized by coating the elastic PB with the AgNF-PU sensing element. The PB/AgNF-PU sensor shows nearly perfect mechanical and electrical reversibility up to 30% strain. It also shows a high initial conductivity (6328 S/cm) and a gauge factor (32.08). As for application demonstrations, the PB/AgNF-PU sensor successfully carries out human motion detection, such as sitting, walking, and running, using a compact microcontroller equipped with wireless communication. The softness and flexibility of the PB/AgNF-PU sensor ensure conformal attachment on human skin, enabling the detection of subtle strain and angular change of knee. Furthermore, it does not restrict joint motion, unlike a conventional rigid brace equipped with an encoder, providing a breakthrough in free motion analysis. The accurate, comfort, and reversible PB/AgNF-PU sensor is synthesized by a facile and scalable process, assembling the high conductivity of AgNFs, stretchability of PU, and elasticity of PB. The PB/AgNF-PU sensor may find immediate applications in rehabilitation and human motion analysis.

Simple and rapid biogenic synthesis of colloidal silver and gold nanoparticles using Aegle marmelos fruit for SERS detection of DNA

In the present communication potential of Aegle Marmelos extract is demonstrated as reducing and stabilizing agent for the eco-friendly synthesis of silver nanoparticles (SNPs) and gold nanoparticles (GNPs). The characteristic surface plasmon resonance peak for SNPs was observed at 425 nm, and that of GNPs was observed at 552 nm. TEM micrographs indicated spherical morphology of synthesized nanoparticles for both the cases with some deviations in GNPs. Spherical shape SNPs lie in between 10 and 30 nm and GNPs are in the range of 15-40 nm. Surface enhanced Raman scattering (SERS) activity of synthesized NPs was investigated using Rhodamine 6 G (R6G). When compared to standard R6G Raman spectrum, significant Raman enhancement was observed in R6G- nanoparticles conjugate. When applied for the SERS detection of DNA, well resolved Raman peaks were observed in SERS spectrum of DNA with the synthesized nanoparticles which favors the application of biosynthesized nanoparticles as SERS substrate.

Advanced Materials in Cancer Therapy

The overview of this review article depends on the various techniques of formation of silver nanoparticles and different application take place in medicinal point of view.
 The branch of nanotechnology plays an important role in medical science research. In this different nanoparticle is synthesized which have various application in gene delivery, drug delivery and reduce the toxic effect of drugs in the human body and also act as an antibacterial in pharmaceutical industries.
 In recent days silver nanoparticles have had an important role due to their optical and catalytic properties. A large number of different particles or methods are used to prepare the different shapes of silver nanoparticles used in drug delivery. Different shapes of nanoparticles have increased their demand in various researches depend on medicinal uses. Silver nanoparticle preparation can be studied by 3 techniques related to irradiations, chemicals, bacteria, fungi, and plants. 
 Nanomedicine have a large number of advantages in treating various chronic diseases by using biological agents, chemotherapeutic agents, and used to deliver the drug to a specific site of the body. A silver nanoparticle is prepared for detection tool to detect the adverse effect of diseases on the target cell. Nanoparticles are used in cancer therapy to remove the damaged cell of the body.

The influence of ion assistance energy on structural and optical properties of carbon-silver nanocomposites

Amorphous carbon structures containing silver nanoparticle inclusions were synthesized by ion-assisted pulse-plasma deposition. Coatings were investigated by transmission electron microscopy, electron diffraction, electron energy loss spectroscopy, Raman spectroscopy and ultraviolet-visible (UV-Vis) absorption spectroscopy. Ion assistance energy variation was found to affect silver nanoparticles shape, carbon matrix composition and clustering. UV-Vis absorption spectra dependence on the structural changes was discussed.

Growth inhibition of tropical fungi by silver nanoparticles incorporated polyurethane coating

Polyurethanes (PUs) have been widely used in the coating industry due to their high flexibility and good UV resistance. Extensive formulations of PU coatings have been reported previously in the literature. Scientists nowadays improvise products whereby nanomaterial additives such as silver nanoparticles are incorporated to obtain antibacterial and antifungal properties. In this study, spherical shaped silver nanoparticles with an average size of 46 nm were added into polyol (polypropylene glycol) which was cross-linked with toluene isocyanate to obtain PU nanocomposite coating films. Characterizations of the coating film were carried out using Fourier transform infrared (FTIR) spectroscopy to observe the urethane linkage that was formed during the cross-linking and Field Emission Scanning Electron Microscope with Energy Dispersive X-Ray (FESEM-EDX) Spectroscopy analysis to determine size, shape and distribution of the nanoparticles. The antifungal activity of the nanocomposite coating was studied against Cladosporium cladosporiodes, Penicillium oxalicum and Aspergillus aculaetus. The results showed that the AgNPs-incorporated PU coating film has the ability to inhibit the tropical fungi growth.

Biosynthesis of silver nanoparticles using Origanum majorana L. and evaluation of their antioxidant activity

The aerial part of Origanum majorana L. was extracted with deionized water and then filtered. The liquid extract was treated with silver nitrate to yield the AgNPs. The maximum absorption was observed at 483 nm in the UV-Vis spectrum. SEM analysis exhibited the spherical shape of silver nanoparticles with an average size of 72.01 nm. The XRD diffraction peaks at 2θ degrees revealed the face-centered cubic crystalline structure. Antioxidant activity of AgNPs and water extract was carried out by DPPH•, ABTS•+, and reducing power assays. AgNPs revealed higher DPPH• scavenging activity (IC50, µg/mL, 12.25) than that of the extract (21.66). Moreover, AgNPs exhibited outstanding ABTS•+ activity (3.87) compared to the standards. The reducing power activity of AgNPs was found (µmol TE/mg extract, 5.09 ± 0.21) the same as the BHT. AgNPs and extract exhibited excellent antioxidant activity promising for usage in food and pharmaceutical applications.

Nipping the Shape of the Nanosilver through Bio-Based Capping Strategy and Studies on Their Electrocatalytic Performance Using Electrospectrometry

The present work involves tuning of the shape of silver nanoparticles from single crystals to nano wires, spheres, and cubes through a bio based-surfactant capping method. The mechanism for the formation of different shapes through preferential adsorption of the surfactant was elucidated using various techniques including XRD, SEM, TEM, UV-visible spectra, and AFM. Furthermore, the electrocatalytic performance of the Ag NPs with different shapes toward the reduction of 4-nitro phenol was studied using electrospectrometric technique. Silver nanowires exhibited superior catalytic efficiency toward the reduction reaction when compared with other shapes. The developed strategy can be employed for tuning the shape of novel nanocatalysts and the employed analytical tool can be utilized for studying the electrocatalytic performance of the developed catalyst toward other technologically relevant organic reactions.

In vivo toxicity and antitumor activity of newly green synthesized reduced graphene oxide/silver nanocomposites

A novel biosynthesis of dual reduced graphene oxide/silver nanocomposites (rGO/AgNC) using the crude metabolite of Escherichia coli D8 (MF06257) strain and sunlight is introduced in this work. Physicochemical analysis of these rGO/AgNC revealed that they are sheet-like structures having spherically shaped silver nanoparticles (AgNPs) with an average particle size of 8 to 17 nm, and their absorption peak ranged from 350 to 450 nm. The biosynthesized rGO/AgNC were characterized by UV–vis and FT-IR spectra, X-ray diffraction, Zeta potential and transmission electron microscopy. After the injection of these nanocomposites to mice, their uptake by the kidney and liver has been proven by the ultrastructural observation and estimation of the hepatic and renal silver content. These nanocomposites caused a moderate toxicity for both organs. Changes in the liver and kidney functions and histopathological effects had been observed. The rGO/AgNC revealed a remarkable antitumor effect. They showed a dose-dependent cytotoxic effect on Ehrlich ascites carcinoma (EAC) cells in vitro. Treatment of mice bearing EAC tumors intraperitoneally with 10 mg/kg rGO/AgNC showed an antiproliferative effect on EAC cells, reduced ascites volume, and maintained mice survival. The results indicate that this green synergy of silver nanoparticles with reduced graphene oxide may have a promising potential in cancer therapy.

A comparative study on the antibacterial activity of different shaped silver nanoparticles

A comparative study on the antibacterial activity of different shaped silver nanoparticles

A New Comparison Between Ag-Nano Adsorbent and Walnut Shell Adsorbent

Silver nanoparticles were synthesised and used as a nano-adsorbent. Silver nanoparticles were added to adsorption system contain a (walnut husks – Manganese ions). The concept of this addition is to enhance the adsorption system due to high surface area to volume ratio of silver nanoparticles. Characterization of walnut husks was done by Fourier transformation infrared (FTIR). Characterization of silver nanoparticles was done also using many techniques, dynamic light scattering (DLS) and field emission scanning electron microscopy (FE-SEM) were used for determination of size and the potential of silver nanoparticles and also to identify the size and the shape of silver nanoparticles. The image showed an average particle diameter in the range (10-85 nm). Energy dispersive X- ray spectra (EDS) was used to examine the quantity of prepared silver nanoparticles. The optimum parameters were studied for this adsorption system such as contact time, weight of adsorpant, effect of pH, manganese concentration and the effect of addition of silver nanoparticles on the (walnut husks –Mn (II) ions) adsorption system. All the experiment parameters were fixed then silver nanoparticles were added to the system contain (walnut husks - Mn (II) ions). The results showed enhancement in the percentage of releasing by 2.2%. The data of the experiment has been investigated through Langmuir, Ferndelsch and Temkin. By evaluating the results, it can be concluded that the adsorption isotherm is most distinct through Freundlich.

Green synthesis and characterization of silver nanoparticles using Indigofera aspalathoides leaf extract and study of its Antibacterial, Antioxidant, and Anti-cancerous activities

Indigofera aspalathoides is an indigenous medicinal plant with copious phytochemical and pharmacological benefits. The crude extract from the leaves of Indigofera apalathoides aids in the bioreduction of silver nitrate into silver ions which results in the formation of colloidal silver nanoparticles. Critical physio-chemical parameters such as temperature, pH, substrate ratio (ratio of leaf extract and silver nitrate solution) and incubation time were optimized to increase the yield and efficiency of the nanoparticle formation. Synthesized nanoparticles were then characterized by performing a set of spectral analyses such as UV, FTIR, XRD, SEM, EDAX and AFM, later its bioactivity was also assessed. Characteristic UV-Vis absorption peak (λmax) at the range of 360-390 nm indicated silver nanoparticle formation and XRD pattern revealed the crystalline nature, while the average grain size was estimated to be 68.5 nm using Scherrer’s formula. SEM image clearly depicted the square shaped silver nanoparticles, which were synthesized using Indigofera aspalathoides leaf extract. Confirmation of formation of silver nanoparticles were carried out using EDAX spectrum. IC 50 value of free radical scavenging occurred at a lower concentration of 300 µg/ml, while a maximum inhibition zone of 13 mm was recorded against pathogenic bacterial strains and 6.7 mm was recorded against pathogenic fungal strains. Further, the silver nanoparticle cytotoxicity analysis was also carried out using MCF 7 cell line and IC 50 was found out to be 5.9 µg/ml. Silver nanoparticles which are green synthesized using the aqueous extract of Indigofera aspalathoides proved as an effective broad-spectrum antibiotic as well as an efficient antioxidant and an anti-cancerous agent.

Green synthesis of silver nanoparticles from Echinacea purpurea (L.) Moench with antioxidant profile

Nanoparticles reveal unique properties due to their application in many fields. The easy, eco-friendly, and cost-effective method for synthesis of silver nanoparticles (AgNPs) from the aerial part of Echinacea purpurea (L.) Moench was demonstrated in this work. The synthesized AgNPs were elucidated by Ultraviolet-visible (UV-Vis), Fourier transform infrared (FTIR), X-ray diffraction (XRD), and Scanning electron microscope (SEM) spectroscopic analyses. The UV-Vis spectrum revealed the maximum absorption at 481 nm and SEM spectral analysis displayed the formation of spherical shape silver nanoparticles with an average size of 68.24 nm. XRD spectral analysis at 2θ degrees of 38.1°, 44.3°, 64.4°, and 77.4° can be indexed to the (111), (200), (220), and (311) Bragg’s reflections of the face-centered cubic crystalline structure. Antioxidant activity of AgNPs and water extract were executed using the 1,1-diphenyl-2-picrylhydrazyl radical (DPPH•) scavenging, 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) radical cation (ABTS•+) scavenging, and reducing power assays. AgNPs and extract exhibited excellent antioxidant activity that could be promising for food and pharmaceutical utilization.

Self-organized plasmonic metasurfaces: The role of the Purcell effect in metal-enhanced chemiluminescence (MEC)

Chemiluminophores are entities, which exhibit wide-band light emission without any external light source, just caused by a chemical reaction. Since chemiluminescence usually yields to unfavorable competition with other channels of chemical energy dissipation, plasmonic nanoparticles can be employed to enhance the chemiluminescence quantum yield via acceleration of the radiative decay rate due to the Purcell effect. On the other hand, the catalytic action of metallic surface can contribute to the chemical reaction rate. Both mechanisms can lead to substantial chemiluminescence intensity enhancement when chemiluminophores are in contact with metal nanoparticles. Although the investigations devoted to MEC are numerous, the relative roles of the Purcell effect and catalysis in the chemiluminescence enhancement are still unclear. In this paper, with the use of a thin inert spacer layer deposited on top of a silver metasurface, we observe a moderate decrease of the chemiluminescence enhancement, which favors an electrodynamic mechanism. We also check that the continuous silver film without plasmon resonances causes no measurable chemiluminescence enhancement. As the results supported the electrodynamic mechanism of MEC, silver nanoparticles with suitable properties have been fabricated via physical vapor deposition on the substrate. We have theoretically optimized the silver nanoparticles shape and size distributions to tune their localized surface plasmon bands for the best overlap with the emission of luminol and some other chemiluminophores. Our design for plasmonic nanoparticles placed on the dielectric material may motivate a new generation of chemiluminescence-based devices for sensing applications.

Facile Electro-Assisted Green Synthesis of Size-Tunable Silver Nanoparticles and Its Photodegradation Activity

An eco-benign procedure was developed to synthesize ultrafine and discrete spherical shape silver nanoparticles (5–20 nm) in the presence of ionic liquid. Different types of leaves extract, including Cymbopogon nardus, Polygonum minus, Allium Cepa, and Petroselinum crispum, were used as a green reducing and capping agents for the synthesis process. The Ag nanoparticles were denoted as AgCN, AgPM, AgAC, and AgPC, respectively. Notably, it was demonstrated that the Ag nanoparticles' size could simply be altered by varying the amount of total phenolic content (TPC) using different leaves. It was indicated from the characterization results that the AgPC nanoparticles’ size was nine-fold smaller compared to the conventional Ag nanoparticles due to the high amount of total phenolic compounds (TPC) in the Petroselinum crispum. The results also revealed that ionic liquid and phenolic compounds had a synergistic effect on reducing silver ions (Ag+) into silver nanoparticles (Ag) and the stabilization of the nanoparticles. The order obtained for the degradation of methylene blue (MB) was AgPC > AgPM > AgCN > AgAC > Ag was influenced by a large amount of TPC and led to a decrease in particle size and enhanced photocatalytic activity. The AgPC remained effective and stable even after five subsequent cycles.