Study of effective parameters in silver nanoparticle synthesis through method of reverse microemulsion

Nanometal surface energy transfer (NSET) from biologically active heterocyclic ligands to silver nanoparticles induces enhanced antimicrobial activity against gram-positive bacteria

Herein we report the formation of a nanometal surface energy transfer (NSET) pair between a donor biologically active heterocyclic luminescent ligand such as 3-(1,3-Dioxoisoindolin-2-yl)-N, N-dimethylpropan-1-ammonium perchlorate (S4PNL; λem-408 nm) and an acceptor silver nanoparticle (Ag NP; λabs-406 nm). When the S4PNL ligand interacts with Ag NPs, the quenching in their luminescence intensity at 408 nm is noticed, with a Stern-Volmer constant of 0.8 × 104 M-1. The present donor-acceptor pair displays a binding constant of 2.8 × 104 M-1 and binding sites of 1.12. The current work shows the energy transfer from a molecular dipole (S4PNL) to a nanometal surface (Ag NP) and thus follows the nanometal surface energy transfer (NSET) ruler with an energy transfer efficiency of 80.0%, 50% energy transfer efficiency distance (d0) of 4.9 nm, donor-acceptor distance of 3.4 nm. The alteration in the zeta potential value of S4PNL upon interaction with AgNP clearly demonstrates the strong electrostatic interaction between donor and acceptor. Importantly, the current NSET pair shows enhanced antimicrobial activity against gram-positive bacteria such as Bacillus cereus (B. cereus) in comparison to their parent components i.e. S4PNL ligand and Ag NP. The NSET pair shows maximum inhibition against B. cereus (9202.21 ± 463.26 CFU/ml.) at 10% while minimum inhibition is observed at 0.01% of it (39,887.19 ± 242.67 CFU/ml.).

A concise review on implications of silver nanoparticles in bone tissue engineering

Skeletal disorders represent a variety of degenerative diseases that affect bone and cartilage homeostasis. The regenerative capacity of bone is affected in osteoporosis, osteoarthritis, rheumatoid arthritis, bone fractures, congenital defects, and bone cancers. There is no viable, non-invasive treatment option and bone regeneration requires surgical intervention with the implantation of bone grafts. Incorporating nanoparticles in bone grafts have improved fracture healing by providing fine structures for bone tissue engineering. It is currently a revolutionary finding in the field of regenerative medicine. Silver nanoparticles (AgNPs) have garnered particular attention due to their well-known anti-microbial and potential osteoinductive properties. In addition, AgNPs have been demonstrated to regulate the proliferation and differentiation of mesenchymal stem cells (MSCs) involved in bone regeneration. Furthermore, AgNPs have shown toxicity towards cancer cells derived from bone. In the last decade, there have been multiple studies focusing on the effect of nanoparticles on the proliferation and/or differentiation of MSCs and bone cancer cells; however, the specific studies with AgNPs are limited. Although the reported investigations show promising in vitro and in vivo potential of AgNPs for application in bone regeneration, more studies are required to ensure their implications in bone tissue engineering. This review aims to highlight the current advances related to the production of AgNPs and their effect on MSCs and bone cancer cells, which will potentiate their possible implications in orthopedics. Moreover, this review article evaluates the future of AgNPs in bone tissue engineering.

Continuous segmented-flow synthesis of Ag and Au nanoparticles using a low-cost microfluidic PTFE tubing reactor

We present in here a simple and low cost continuous segmented-flow process for the synthesis of Ag and Au spherical-shaped nanoparticles. Different residence times (RT) were used to perform the nanoparticle synthesis, observing that at low RT, the Ag nanoparticles production, which uses a fast reduction reaction with NaBH4, is improved due to an enhancement in the mixing of the reactants. However, the flow conditions have an opposite effect in the case of Au nanoparticles synthesis. Indeed, since the chemical reduction process (Turkevich method) exhibit a much slower kinetics, high RT (low flowrates) improve the synthesis yield and the quality of the nanoparticles. The Ag and Au nanoparticles were characterized by UV-Vis spectrophotometry (UV-Vis) and Transmission Electron Microscopy (TEM). The Ag spherical-shaped nanoparticles presented a LSPR at 400 nm (size ≈ 4 nm), while the synthesized Au nanoparticles exhibit LSPR and sizes in the range 520 - 550 nm and 14 - 17 nm, respectively.

Characterization of self-assembled silver nanoparticle ink based on nanoemulsion method

A well-dispersed self-assembled silver nanoparticles (AgNPs) ink with high purity was synthesized via AgNO₃ emulsion prepared by blending an AgNO₃ aqueous solution and a liquid paraffin solution of both polyoxyethylene (20) sorbitan monooleate (Tween 80) and sorbitan monooleate (Span 80). The ink remained as an emulsion at low temperatures; however, it produced AgNPs after sintering at about 60°C and showed a high stability at nanoscale sizes (with diameters ranging 8.6-13.4 nm) and a high conductivity. During the whole procedure, Tween 80 acted as a surfactant, reductant and stabilizer. Presumably, Tween 80 underwent an autoxidation process, where a free radical of an α-carbon of ether oxygen was formed by hydrogen abstraction. The mean diameter of emulsion droplets could be reduced by decreasing water content and increasing the ratio of surfactant and concentration of AgNO₃ aqueous solution. Consequently, the thermogravimetric analysis and X-ray diffraction result clarified the purity of the produced Ag⁰. Dynamic light scattering and ultraviolet-visible spectroscopy clarified that an increased concentration of AgNO₃ decreased the particle size.

Tannic acid stabilized silver nanoparticles for inkjet printing of conductive flexible electronics

Tannic acid stabilized silver nanoparticles were prepared as conductive inks for fabricating conductive patterns using a common color inkjet printer.

Linear Polyethers as Additives for AOT-Based Microemulsions: Prediction of Percolation Temperature Changes Using Artificial Neural Networks

Predictive models based on artificial neural networks have been developed for the percolation threshold of AOT based microemulsions with addition of either glymes or polyethylene glycols. Models have been built according to the multilayer perceptron architecture, with five input variables (concentration, molecular mass, log P, number of C and O of the additive). Best model for glymes has a topology of five input neurons, five neurons in a single hidden layer and one output neuron. Polyethylene glycol model's architecture consists in five input neurons, three hidden layers with eight neurons in both first two and five in the last, and a neuron in the last output layer. All of them have a good predictive power according to several quality parameters.