Surface-enhanced Raman scattering (SERS) spectroscopy is a powerful technology in trace analysis. However, the wide applications of SERS in practice are limited by the expensive substrate materials ...and the complicated preparation processes. Here we report a simple and economical galvanic-replacement-assisted synthesis route to prepare Ag nanoparticles on Cu(0) foil (nanoAg@Cu), which can be directly used as SERS substrate. The fabrication process is fast (ca. 10 min) and easily scaled up to centimeters or even larger. In addition, the morphology of the nanoAg@Cu (with Ag particles size from 30 nm to 160 nm) can be adjusted by various additives (e.g., amino-containing ligands). Finally, we show that the as-prepared nanoAg@Cu can be used for SERS characterization of two-dimensional polymers, and ca. 298 times relative enhancement of Raman intensity is achieved. This work offers a simple and economical strategy for the scalable fabrication of silver-based SERS substrate in thin film analysis.
Hydroxyapatite (HAp) and bacterial cellulose (BC) composite materials represent a promising approach for tissue engineering due to their excellent biocompatibility and bioactivity. This paper ...presents the synthesis and characterization of two types of materials based on HAp and BC, with antibacterial properties provided by silver nanoparticles (AgNPs). The composite materials were obtained following two routes: (1) HAp was obtained in situ directly in the BC matrix containing different amounts of AgNPs by the coprecipitation method, and (2) HAp was first obtained separately using the coprecipitation method, then combined with BC containing different amounts of AgNPs by ultrasound exposure. The obtained materials were characterized by means of XRD, SEM, and FT-IR, while their antimicrobial effect was evaluated against Gram-negative bacteria (Escherichia coli), Gram-positive bacteria (Staphylococcus aureus), and yeast (Candida albicans). The results demonstrated that the obtained composite materials were characterized by a homogenous porous structure and high water absorption capacity (more than 1000% w/w). These materials also possessed low degradation rates (<5% in simulated body fluid (SBF) at 37 °C) and considerable antimicrobial effect due to silver nanoparticles (10–70 nm) embedded in the polymer matrix. These properties could be finetuned by adjusting the content of AgNPs and the synthesis route. The samples prepared using the in situ route had a wider porosity range and better homogeneity.
The book proposes extensive and varied design strategies for bone tissue engineering. The design process of materials for bone tissue scaffolds presently represents an issue of crucial importance and ...is being studied by many researchers throughout the world. A number of studies have been conducted, aimed at identifying the optimal material, geometry, and surface that the scaffold must possess to stimulate the formation of the largest amounts of bone in the shortest time possible.
The paper presents sorption behavior of
Arachis hypogaea
shells towards silver ions and possibility of their use as antimicrobial product. During the modification process of the natural sorbent, ...equilibrium tests were carried out. Moreover, the possibility of obtaining biocomposite
Arachis hypogaea
shells/nAg has been determined, and its antimicrobial properties have been evaluated. Additionally, sorption kinetics has been calculated. In the last step, silver ions were desorbed. The conducted equilibrium tests allowed to adjust the sorption isotherm model and determine the sorption capacity of tested material. This process is best described by Freudlich’s isotherm, and the sorption capacity is equal to 12.33 mg/g. On the basis of kinetic studies, the chemical nature of this process has been proved (by choosing a pseudo-second order model for the sorption process). It has been confirmed that the obtained peanut shells modified with silver ions have antimicrobial properties. The tests allowed to obtain 100% inhibition of
Aspergillus niger
and ~ 98%
Escherichia coli
.
Silver nanoparticles (nanoAg) incorporated poly(3,4-ethylene dioxythiophene-sodium dodecyl sulfate) (PEDOT
SDS) modified electrode was prepared by electrochemical deposition method. Hereafter, the ...above-modified electrode denoted as PEDOT
SDS–nanoAg electrode. The nanoAg formation was confirmed by UV–vis spectroscopy and it shows surface plasmon resonance (SPR) peak at 375
nm. The surface morphology, film thickness, and surface roughness of PEDOT
SDS–nanoAg electrode were studied using atomic force microscopy (AFM). The PEDOT
SDS–nanoAg electrode has been utilized as a platform to immobilize electrochemically active mediator, Meldola Blue (MDB), by means of electrostatic trapping and the electrode denoted as PEDOT
SDS–nanoAg–MDB electrode. At 750
s of silver deposition time, reversible redox peak of MDB, which existed on PEDOT
SDS–nanoAg–MDB electrode, was obtained and that time was found to be an optimum. The electrochemical properties of the PEDOT
SDS–nanoAg–MDB electrode were studied by cyclic voltammetry (CV). The PEDOT
SDS–nanoAg–MDB electrode was investigated for catalytic application, which shows electrocatalytic activity towards the oxidation of NADH (dihydronicotinamide adenine dinucleotide) with 650
mV decrease in overpotential in comparison with bare glassy carbon electrode. Using the PEDOT
SDS–nanoAg–MDB electrode, the amperometric measurements were performed at an applied potential of −0.05
V and a linear response of NADH was obtained in the range from 10 to 560
μM with a limit of detection (LOD) of 0.1
μM. The PEDOT
SDS–nanoAg–MDB electrode showed diminished response to its interferences.
Protein is the functional actor of life. Research on protein damage induced by nanomaterials may give insight into the toxicity mechanisms of nanoparticles. Studying nano silver over the impact of ...the structure and function of catalase (CAT) at the molecular level, is of great significance for a comprehensive evaluation of their toxic effects. The toxic effects of nanoAg on catalase were thoroughly investigated using steady state and time resolved fluorescence quenching measurements, ultraviolet-visible absorption spectroscopy, resonance light scattering spectroscopy (RLS), circular dichroism spectroscopy (CD) and transmission electron microscopy (TEM). NanoAg could decrease the amount of alpha-helix and increase the beta sheet structure, leading to loose the skeleton structure of catalase. The characteristic fluorescence of catalase was obviously quenched, which showed the exposal of internal hydrophobic amino acids enhanced, and its quenching type is dynamic quenching. The result of RLS and TEM showed that the distribution and size of nanoAg become more uniform and smaller after their interaction, resulting in a decrease of RLS intensity. NanoAg could make the activity of catalase rise. By changing the structure of catalase, nanoAg increases its enzymatic activity to a certain extent, breaking down its balance in vivo, thereby affecting the normal physiological activities. NanoAg has obvious toxic effects on catalase. This paper provided a new perspective and method for the toxic effects of nanoAg to biological macromolecules; provided basic data and reference gist for the hygienics and toxicology studies of nanoAg. It is conducive to the toxicity prevention and control work of nanoAg, promoting nano-technology applied to human production and living better.
Polyethylene oxo-degradable composites containing antibacterial substances in the form of vegetable oils: geranium, clove and eucalyptus as well as a mixture of nanoAg with nanoCu were discussed. ...Antibacterial fi lm: PE-0, PE- 1A, PE-2B, PE-3C, PE-4D properties were verifi ed according to ISO 22196:2011 “Measurement of antibacterial activity on plastic and other non-porous surfaces” for the two standard bacteria species of E. coli and S. aureus, whereas water vapour permeability tests (Pv) were carried out acc. ISO 15106-2007 “Plastics. Foils and plates. Determination of water vapor transmission rate. Part 1: Humidity sensor method”. Film marked PE-4D showed the best antibacterial features and good barrier properties.
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