Controlled release of monodisperse silver nanoparticles via in situ cross-linked polyvinyl alcohol as benign and antibacterial electrospun nanofibers

A facile methodology was explored by using glutaraldehyde as a cross-linking reagent for in situ modification of polyvinyl alcohol (PVA) electrospun nanofibers doped with monodisperse silver nanoparticles (AgNPs) via the one-pot reactions. The hydroxyl groups along the PVA molecule chains can serve as both the reactive sites and stabilizers for AgNPs. Meanwhile, the cross-linking degree can be easily tuned by controlling the charged amounts of glutaraldehyde to obtain either partial or cured cross-linked PVA nanofibrous mats doped with AgNPs. It was revealed that such different cross-linking degrees could effectively control the release contents and rates of the embedded Ag to the surrounding aqueous solution. Furthermore, such release behavior was also found to be pH-responsive and acid-labile due to the formation of acetal groups during the cross-linking reactions. Besides both the partial and cured cross-linked PVA doped with Ag nanoparticles can still bear good antibacterial efficacy against S. aureus while have low cytotoxicity against mouse embryo fibroblasts (NIH3T3), human embryonic kidney cells (293T) and human histiocytic lymphoma cells (U937).

Facile In Situ Cross-Linked Robust Three-Dimensional Binder for High-Performance SiOx Anodes in Lithium-Ion Batteries

Silicon oxide (SiO_x, 0 < x < 2) is considered one of the most promising anode materials for next-generation lithium-ion batteries due to its high theoretical capacity. However, its commercial application is limited by the non-negligible volume change during cycling. Herein, a three-dimensional (3D) structure of carboxymethyl cellulose (CMC) cross-linked with iminodiacetic (c-CMC-IDA₁₅₀) was facilely formed through in situ thermal cross-linking of CMC and iminodiacetic acid (IDA) in the fabrication process of the electrode, which could construct a robust network to restrain the volume change of the SiO_x anode and maintain the integrity of the electrode. In addition, the 3D cross-linked c-CMC-IDA₁₅₀ provides sufficient contact sites to improve the adhesive strength. Thus, SiO_x@c-CMC-IDA₁₅₀ shows a prolonged cycle life, achieving a capacity of 1020 mAh g^-1 after 100 cycles at a current density of 0.2 A g^-1. With the increase in the current density to 1.0 A g^-1, SiO_x@c-CMC-IDA₁₅₀ exhibits a reversible capacity of 899 mAh g^-1 after 200 cycles with a capacity retention of 70.2%. This work provides a potential perspective to fabricate high-performance SiO_x anodes and promote the stability of high-capacity Si-based anodes.

Characterization and stability evaluation of Ca2+ cross-linked soybean protein isolate/chitosan/sodium alginate ternary complex coacervate phase

To improve the stability of the soybean protein isolate/chitosan/sodium alginate ternary complex coacervate phase against environmental pH and ionic strength, the complex ternary phase cross-linked by Ca²⁺ was characterized and evaluated. The viscoelastic properties, thermal properties, microstructure, and texture profile were characterized using rheology, differentia scanning calorimetry as well as thermmogravimetric analysis, scanning electron microscopy as well as transmission electron microscopy, and texture profile analysis, respectively. Compared with the uncross-linked ternary complex coacervate, the complex in situ cross-linked with 1.0 % Ca²⁺ for 1 h still retains its typical solid characteristics, and has a more compact network structure and better stability. Our research results also showed that prolonging the cross-linking time (from 3 h to 5 h) and increasing the concentration of the cross-linking agent (from 1.5 % to 2.0 %) did not further improve the rheological, thermodynamic and textural properties of the complex coacervate. The ternary complex coacervate phase cross-linked in situ under 1.5 % concentration of Ca²⁺ for 3 h showed significantly improved stability at low pH 1.5-3.0, which indicats that the ternary complex coacervate phase cross-linked in situ by Ca²⁺ can be used as a potential delivery platform for the effective delivery of biomolecules under physiological conditions.