Nanosilver Sol Research Articles

Serum analysis based on SERS combined with 2D convolutional neural network and Gramian angular field for breast cancer screening

Breast cancer is a significant cause of death among women worldwide. It is crucial to quickly and accurately diagnose breast cancer in order to reduce mortality rates. While traditional diagnostic techniques for medical imaging and pathology samples have been commonly used in breast cancer screening, they still have certain limitations. Surface-enhanced Raman spectroscopy (SERS) is a fast, highly sensitive and user-friendly method that is often combined with deep learning techniques like convolutional neural networks. This combination helps identify unique molecular spectral features, also known as “fingerprint”, in biological samples such as serum. Ultimately, this approach is able to accurately screen for cancer. The Gramian angular field (GAF) algorithm can convert one-dimensional (1D) time series into two-dimensional (2D) images. These images can be used for data visualization, pattern recognition and machine learning tasks. In this study, 640 serum SERS from breast cancer patients and healthy volunteers were converted into 2D spectral images by Gramian angular field (GAF) technique. These images were then used to train and test a two-dimensional convolutional neural network-GAF (2D-CNN-GAF) model for breast cancer classification. We compared the performance of the 2D-CNN-GAF model with other methods, including one-dimensional convolutional neural network (1D-CNN), support vector machine (SVM), K-nearest neighbor (KNN) and principal component analysis-linear discriminant analysis (PCA-LDA), using various evaluation metrics such as accuracy, precision, sensitivity, F1-score, receiver operating characteristic (ROC) curve and area under curve (AUC) value. The results showed that the 2D-CNN model outperformed the traditional models, achieving an AUC value of 0.9884, an accuracy of 98.13%, sensitivity of 98.65% and specificity of 97.67% for breast cancer classification. In this study, we used conventional nano-silver sol as the SERS-enhanced substrate and a portable laser Raman spectrometer to obtain the serum SERS data. The 2D-CNN-GAF model demonstrated accurate and automatic classification of breast cancer patients and healthy volunteers. The method does not require augmentation and preprocessing of spectral data, simplifying the processing steps of spectral data. This method has great potential for accurate breast cancer screening and also provides a useful reference in more types of cancer classification and automatic screening.

A rapid localization and analysis method for isoquinoline alkaloids with fluorescence in Coptis chinensis Franch. By fabricating the nano-silver sol as a substrate for surface-enhanced Raman spectroscopy

BackgroundThe quality of traditional Chinese medicines (TCMs) directly impacts their clinical efficacy and drug safety, making standardization a critical component of modern TCMs. Surface-enhanced Raman spectroscopy (SERS) is an effective physical detection method with speed, sensitivity, and suitability for large sample analyses. In this study, a SERS analysis method was developed using a nano-silver sol as the matrix to address the interference of fluorescence components in TCMs and overcome the limitations of traditional detection methods. ResultsThe higher sensitivity and efficiency of SERS was used, enabling detection of a single sample within 30 s. Coptis chinensis Franch. (CCF) was chosen as the model medicine, the nano-silver sol was used as the matrix, and CCF’s fourteen main fluorescent alkaloids were tested as index components. Typical signal peaks of the main components in CCF corresponded to the bending deformation of the nitrogen-containing ring plane outer ring system, methoxy stretching vibration, and isoquinoline ring deformation vibration. Through SERS detection of different parts, the distribution content of the main active components in the cortex of CCF was found to be lower than that in the xylem and phloem. Additionally, rapid quality control analyses indicated that among the nine batches of original medicinal materials purchased from Emei and Guangxi, the main active ingredient showed a higher content. SignificanceA SERS-based method for the rapid localization and analysis of multiple components of TCMs was established. The findings highlight the potential of SERS as a valuable tool for the analysis and quality control of TCMs, especially for fluorescent components.

Preparation of SERS substrate with 2D silver plate and nano silver sol for plasticizer detection in edible oil

As a widely used industrial additive of plastic products, phthalate ester (PAE) plasticizers can easily migrate into food, threatening human health. In this work, we proposed a rapid, precise, and reliable method to detect PAE plasticizers in edible oils by using surface-enhanced Raman spectroscopy (SERS) technology. A two-dimensional (2D) silver plate synergizing with a nanosilver sol was prepared as a substrate for SERS to detect potassium hydrogen phthalate (PHP), a hydrolysate of a PAE plasticizer. Detection conditions, such as pH values, drying times, and hydrolysate interference, were optimized. The working curve was well fitted with a linear parameter R2 of 0.9994, and the minimum detection limit was evaluated as 10−9 mol/L. Furthermore, the detection accuracy was supported by five edible oil samples. Therefore, using SERS technology to detect PHP is expected to provide an avenue for PAE plasticizer detection in oils and fats, and it features promising potential applications in food safety.

A Highly Selective and Sensitive Nano-Silver sol Sensor for Hg2+ and Fe3+: Green Preparation and Mechanism.

The development of highly selective and highly sensitive nanometer colorimetric chemical sensors is an urgent requirement in the immediate detection of heavy metal ions. In this work, silver-nanoparticle (Ag NPs)-based chemosensors were prepared by a simple and green method, in which the silver nitrate, carboxymethyl cellulose sodium (CMS) and Polyvinylpyrrolidone (PVP), and glucose are used as the silver source, double stabilizer and green reductant, respectively. The obtained colloidal CMS/PVP-Ag NPs showed a high dispersibility and stability, and creating a high selectivity and sensitivity to detect Hg2+ and Fe3+ with remarkable and rapid color variation. Low limits of detection (LOD) of 7.1 nM (0–20 μM) and 15.2 nM (20–100 μM) for Hg2+ and 3.6 nM for Fe3+ were achieved. More importantly, the CMS/PVP-Ag NPs has a high sensitivity even in a complex system with multiple heavy ions, the result of the practical ability to detect Hg2+ and Fe3+ in tap water and seawater reached a rational range of 98.33~104.2% (Hg2+) and 98.85~104.80% (Fe3+), indicating the great potential of the as-prepared nanocomposites colorimetric chemosensor for practical applications.

Preparation and characterization of cinnamaldehyde/polyvinyl alcohol/silver nanoparticles ternary composite films

An environmentally friendly method has been proposed to synthesize silver nanoparticles using polyvinyl alcohol (PVA)-cinnamaldehyde (CIN) microemulsion. Ternary composite films with different concentration of Ag-NPs were prepared by solution casting method. The formation of Ag-NPs was confirmed by measuring surface plasmon resonance (SPR) peak. The SPR peak of Ag-NPs did not change after three months later, suggesting that the Ag-NPs stability without aggregation. Scanning electron microscopy (SEM) demonstrated that the Ag-NPs were uniformly dispersed in the film. The tensile strength and water vapor transmission rate of the composite film enhanced (p < 0.05) with the proportion of nano-silver increased, whereas the elongation at break unchanged. The composite film exhibited a strong antibacterial activity against both E. coli and S. aureu food-borne pathogenic bacteria. These finding suggest that the nano-silver sol obtained by PVA-CINmicroemulsion can be effectively utilized to prepare antibacterial eco-friendly food packaging material.

Антибактериальная активность биодеградируемых частиц на основе хитозана, содержащих коллоидное серебро

Chitosan beads with colloidal silver nanoparticles inclued in the polymer matrix have been obtained by the introduction of chitosan into an acidified nanosilver sol. Dual interconnection of drops of the resulting solution was then carried out by ionotropic gelation at the first stage and covalent crosslinking of the polymer matrix with adipic acid at the second stage. The surface morphology of the obtained beads was studied by scanning electron microscopy. Data of Fourier transform IR spectroscopy confirmed the formation of covalent bonds between chitosan and adipic acid. The antibacterial activity of obtained beads against S. aureus and E. coli was evaluated using agar diffusion test. It was shown that the сhitosan beads modified with nanostructured silver exhibited an antibacterial effect against the tested strains, and they can be used as a basis for creating biodegradable wound healing dressings with a prolonged antibacterial effect. chitosan, silver nanoparticles, antibacterial activity, wound dressings This work was supported by the "Russian Academic Excellence Project 5-100". The study was carried out with the financial support of the Russian Foundation for Basic Research in the framework of the Scientific Project no. 18-29-18039.

Innovative Pre‐Treatment for Fabrication of Conductive PMIA Fibers via Electroless Nickel Plating

To achieve the admirable electrically conductivity without sacrificing the outstanding integrated performance of meta‐aramid fibers is still a challenge. A novel method is developed for fabricating of electrically conductive poly (m‐phenylene isophthalamide) (PMIA) fibers in this paper. Firstly, the metal silver nanoparticles are deposited on the surface of PMIA fibers by simply dipping the fibers into a mixed aqueous suspension of dimethylsulfoxide (DMSO) and nano silver sol. Then, the silver nanoparticles, depositing on the surface of the PMIA fibers, are functioned as the catalyst for the subsequent procedure of electroless nickel deposition together with the anchor for the coating layer. Followed by electroless nickel plating, homogeneous and dense nickel‐coated PMIA fibers are obtained. And the properties and structures of nickel‐coated PMIA fibers are investigated systematically, the electrical resistance of the nickel‐coated PMIA fibers is measured using the multimeter. Without any post‐treatment, the electrical resistance of the modified PMIA fibers can be as low as 5.5 Ω cm−1. Meanwhile, outstanding mechanical performances of pure PMIA fibers are well maintained. This study also demonstrates the necessity of adding a small amount of DMAB as an auxiliary reducing agent. This approach may be equally applicable to fabricate conductive coatings on other polymer materials.

A simple and sensitive SERS quantitative analysis method for urea using the dimethylglyoxime product as molecular probes in nanosilver sol substrate

Under the light wave irradiation, the stable and highly surface enhanced Raman scattering (SERS) active silver nanosol (AgNP) was prepared by reduction of AgNO3, using sodium citrate as reducer. Urea reacted with dimethylglyoxime to produce 4,5-dimethyl-2-imidazole ketone that exhibited a strong SERS peak at 1320 cm−1 in the as-prepared AgNPs substrate. Under the selected conditions, the increased SERS intensity ΔI was linear to urea concentration in the range of 8.25–825 nM, with a detection limit of 4.92 nM. Accordingly, a new, simple SERS quantitative analysis method for trace urea in foods was established, with relative standard deviation of 0.92–4.8% and recovery of 97.4–101%.

A highly sensitive enzyme catalytic SERS quantitative analysis method for ethanol with Victoria blue B molecular probe in the stable nanosilver sol substrate

Using AgNO3 as precursor, a stable silver nanosol with strong SERS activity was prepared rapidly by light-wave procedure. A highly sensitive SERS quantitative analysis method for ethanol was developed, coupled the alcohol oxidase catalytic reaction with the Fe2+ catalytic reaction that the produced hydroxyl radicals not only oxidized the silver atoms on the nanosilver surface to form more dispersed and small size nanosilvers with weak SERS effect, but also oxidized the molecular probe Vitoria blue B (VBB) to fade. With the increasing of ethanol concentration, the more nanosilver and probe molecules were oxidized, resulting in SERS intensity decreasing at 1615 cm−1. The decreased SERS intensity was linear to ethanol in the range of 0.008–0.40 mg/L, with a detection limit of 3 μg/L. This method was applied to determination of ethanol in beer and serum samples, with satisfactory results.

Facile synthesis of a highly SERS active nanosilver sol using microwaves and its application in the detection of E. coli using Victoria blue B as a molecular probe

A green microwave procedure was developed to synthesize highly surface-enhanced Raman scattering (SERS) active silver nanoparticles (AgNPs) with a resonance Rayleigh scattering (RRS) peak at 450 nm, and a new SERS enhancement mechanism was proposed.

Highly sensitive fluorescence and SERS detection of azide through a simple click reaction of 8-chloroquinoline and phenylacetylene.

In 0.19 mol/L acetic acid (HAc), a click reaction of 8-chloroquinoline/azide/phenylacetylene take places in aqueous solution without Cu(I) as a catalyst. 8-Chloroquinoline (CQN) exhibited a strong fluorescence peak at 430 nm that was quenched linearly as the concentration of azide increased from 20 to 1000 ng/mL. This quenching was due to consumption of CQN in the click reaction and a decrease in the number of efficiently excited photons due to the presence of triazole-quinoline ramification molecules with strong hydrophobicity. Using blue nanosilver sol as the substrate, CQN absorbed onto the surface of nanosilver particles, showing a strong surface-enhanced Raman scattering (SERS) peak at 1585 cm(-1) that decreased linearly as the azide concentration increased from 8 to 500 ng/mL; the detection limit was 4 ng/mL. Thus, two new, simple and sensitive fluorescence and SERS methods have been developed for the determination of azide via the click reaction.

Synthesis of Monodispersed Lauric Acid Capped Silver Nanoparticles by Wet-Chemical Reduction Method

Silver nanoparticles with narrow distribution were prepared by a simple route in water in presence of lauric acid as the capping agents. The morphology and crystal structure of as-synthesized silver nanoparticles were analyzed by transmission electron microscopy (TEM) and X-ray powder diffraction (XRD). The mass ratio of lauric acid and silver nitrate, the reaction temperature play important roles on the morphology and size of the silver nanoparticles. Well-dispersed silver nanopartilces with diameter of 8 nm were obtained when the mass ratio of lauric acid and silver nitrate was 1.2:1 and the reaction temperature was room temperature. It is also confirmed that the sol system was monodisperse nanosilver sol.

Surface-Enhanced Raman Scattering Determination of Trace Phenanthroline Using Aggregated-Nanosilver as Substrate

Using PEG10000 and sodium citrate as stabilizer, sodium borohydride as reducing agent, a stable nanosilver sol had been prepared. In pH 6.0 Na2HPO4- NaH2PO4buffer solution and in the presence of NaCl, a stable nanosilver aggregates were formed. Phenanthroline (Phen) adsorbed on the aggregated-nanosilver surfaces resulting in a surface-enhanced Raman scattering (SERS) peak at 1450 cm-1observed, and the SERS intensity was enhanced with the concentration of Phen was between 1.25×10-10mol/L and 2.5×10-9mol/L. Based on these, a new sensitive SERS method has been proposed for the determination of trace Phen in the synthesis of samples, with satisfactory results.

Preparation of Green Nanosilver by Ascorbic Acid and its Spectral Properties

In the presence of stabilizer of citrate and room temperature, stable green nanosilver sol was prepared by reduction of AgNO3by ascorbic acid. It was characterized by UV-visible spectroscopy, resonance Rayleigh scattering (RRS) spectroscopy, laser scattering and transmission electron microscopy. Results showed that the nanosilver sol exhibited a RRS peak at 496 nm, a strong absorption peak at 414 nm and the particle size is 12 nm.

Green Synthesis of Highly Pure Nano-Silver Sols—Electrolysis

Abstract The highly pure nano-silver sols were prepared by an electrolysis method using two highly pure silver flakes as electrodes and deionized water as electrolytic solution, and PVP served as stabilizer. The effects of PVP content, electrolytic time and current density on the colloidal silver nanoparticles were researched. The results indicate that as-synthesized particles were spherical about 1∼3 nm in size, and monodispersed and its concentration reached to 130 μg/g under the condition of 5.0 wt% PVP with current density about 1∼2 mA/cm 2 for 150 min. Moreover, the nano-silver sol had such an excellent stability that it had not any change though it was placed in dark at room temperature for 6 months.

Polyaniline/Ag nanocomposite synthesized by using aniline as dispersant and stabilizer of nanosilver sol

Polyaniline/silver (PANI/Ag) nanocomposite was successfully prepared by in-situ polymerization from nanosilver sol using aniline (An) as both dispersant and stabilizer and characterized by FT-IR, XRD SEM, TEM and electrochemical methods, respectively. The results showed that core-shelled composite particles of less than 100 nm were synthesized with PANI as shell formed around a core of silver nanoparticles at higher aniline levels. Compared to pure PANI, PANI/Ag nanocomposites have higher electrical conductivity (65.98 S/cm) and current response and capacitance as well. Potentio dynamic polarization showed the anodic shifting of zero current potential and a lower exchange current density for the PANI/Ag composite. Compared with PANI, the PANI/Ag nanocomposite is a promising candidate for coatings with improved anti-corrosion performance. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

Antibacterial Activity of Silver Nanoparticles Colloidal Sol and its Application in Package Film

Using starch as the stabilizing agent, glucose as reducing agent, nano-size silver particles colloidal sols have been synthesized via ultrasonic irritation in aqueous solution. The nanoparticles size distribution in typical colloidal sol is from 15 to 45 nm. The silver nanoparticles-PE blend film with silver content of 86 ppm was prepared by mixing silver nanoparticles colloids sol with the PE master batch and then by film blowing. The silver nanoparticles-PE blend film and the prepared nano-silver sol show effective antibacteial activity to the Staphylococcus aureus and Escherichia coli. The pear fruit package application of the silver nanoparticles-PE blend film has demonstrated that the film has effective fresh preservation ability for the packaged fruits and vegetables.

Synthesis and characterization of silver nanoparticles in AOT microemulsion system

Colloidal silver nanoparticles have been synthesized in water-in-oil microemulsion using silver nitrate solubilized in the water core of one microemulsion as source of silver ions, hydrazine hydrate solubilized in the water core of another microemulsion as reducing agent, dodecane as the oil phase, sodium bis(2-ethylhexyl) sulfosuccinate (AOT) as the surfactant. The UV–vis absorption spectra and transmission electron microscopy (TEM) have been used to trace the growth process and elucidate the structure of the silver nanoparticles. UV–vis spectra show that the Ag 4 + intermediates formed at early stages of the reaction and then the clusters grow or aggregate to larger nanoparticles. TEM micrographs confirm that the silver nanoparticles are all spherical. The resulting particles have a very narrow size distribution. Meanwhile, the diameter size of the particles is so small that the smallest mean diameter is only 1.6 nm. IR results show that the surfactant molecules are strongly adsorbed on the surface of silver particles through a coordination bond between the silver atom and the sulfonic group of AOT molecules, which endows the particles with a good stability in oil solvents. As dodecane is used as oil solvent to prepare silver nanoparticles, the formed nano-silver sol is almost nontoxic. As a result, the silver nanoparticles need not be separated from the reaction solution and the silver sol may be directly used in antibacterial fields.