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A facile photoreduction strategy to attach silver nanoparticles on filter paper (AgNPs@FP) to form surface-enhanced Raman scattering (SERS) substrate array was proposed and examined. As prepared, SERS substrate array was applied to detect low concentration of adenine and other nucleobases in aqueous solutions. In addition, the formed SERS substrate array allows mass analysis of aqueous samples with a requirement of only 10 μL in sample volume. To optimize and understand the parameters in preparations, factors such as the concentrations of citrate and silver nitrate, photoreduction time, and concentration of sodium hydroxide were varied and examined. Para-nitrothiophenol was used as a Raman probe molecule and scanning electron microscope (SEM) images of the substrates were used to explore the influences of experimental factors in the preparation of SERS array. Results indicated that silver ions could be effectively reduced and deposited in/on filter paper with the presence of citrate. The formed AgNPs@FP exhibits a three-dimensional structure as the particles formed on and beneath the surface of the cellulosic fibers could be observed. Deposition of analyte on restricted substrate array rendered reproducible results and the spot-to-spot SERS intensity varied within 8%. At optimal conditions, the substrate enhancement factor approached 107. We demonstrated that the filter paper-based SERS substrates can be used as a suitable tool for biological analysis, and a limit of detection better than 160 nM was obtained in detection of adenine molecules in aqueous solutions with a linear range up to 20 μM. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Silver nanoparticles have shown inhibitory capabilities and its use in battling viral infections are strengthened by its potent antibacterial activity. Notably, since it directly affects antiviral efficacy, the proper choice of synthesis process for making silver nanoparticles is a vital element to be taken into consideration. The synthesis of silver nanoparticles for the treatment of viral and bacterial infections involves creating silver particles at the nanoscale with unique antimicrobial properties. Various methods exist for synthesizing silver nanoparticles, including chemical reduction, green synthesis, and physical methods. Chemical reduction involves using reducing agents to convert silver ions into silver nanoparticles. Green synthesis employs reducing agents in an environmentally friendly manner. Physical methods rely on techniques such as laser ablation or thermal evaporation to produce silver nanoparticles. In order to provide technological guidance for choosing antiviral silver nanoparticle manufacturing methods, this paper introduces and explores alternative synthesis methods for creating silver nanoparticles. [ABSTRACT FROM AUTHOR]

This work narrates the synthesis of poly (acrylic acid) hydrogel microparticles (PAAHMPs), fabrication of silver nanoparticles (AgNPs) inside the structure of the prepared PAAHMPs and catalytic applications of PAAHMPs fabricated with AgNPs (PAAHMPs/AgNPs). The PAAHMPs were prepared by inverse suspension polymerization technique while fabrication of AgNPs was carried out by chemical reduction method using sodium borohydride (NaBH4) as reducing agent. The identification of functional groups in bare PAAHMPs and in the PAAHMPs/AgNPs composite system was carried out by the Fourier transform infrared spectroscopy. The size and morphology of the prepared hydrogel and its composite was studied by scanning electron microscopy and transmission electron microscopy. X‐ray diffraction and thermal gravimetric analyzer was also used to characterize the bare PAAHMPs and PAAHMPs/AgNPs composite. The prepared PAAHMPs/AgNPs composite was used as catalyst for the reduction of nitro aromatic pollutants and an industrial dye, that is, 4‐Nitrophenol (4‐NP), 2‐Nitrophenol (2‐NP) and methyl orange. No loss in catalytic activity was noted in seven consecutive cycles of recycling process while only 37.5% loss in catalytic activity was observed upon storing the catalyst for 90 days. [ABSTRACT FROM AUTHOR]

A new type of water soluble PEG core dendrimer having hydroxyl groups at the periphery was synthesized and used to prepare silver nanoparticles. The dendrimer and the dendrimer encapsulated nanoparticles (DENs) were characterized by spectroscopic techniques. The kinetics of catalytic activity of the prepared silver nanoparticle on the reduction of 4-nitrophenol to 4-aminophenol by NaBH4 as a reductant was studied using UV-Visible spectrophotometer. [ABSTRACT FROM AUTHOR]