Soft and flexible hydrogel templates of different sizes and various functionalities for metal nanoparticle preparation and their use in catalysis

Green synthesis of a natrolite zeolite/palladium nanocomposite and its application as a reusable catalyst for the reduction of organic dyes in a very short time

A natrolite zeolite/palladium (natrolite zeolite/Pd) nanocomposite has been successfully synthesized applying a simple in situ reduction method using an aqueous extract of fruits of Piper longum as a reducing and stabilizing agent.

Tough and elastic hydrogel of hyaluronic acid and chondroitin sulfate as potential cell scaffold materials

Natural polysaccharides are extensively investigated as cell scaffold materials for cellular adhesion, proliferation, and differentiation due to their excellent biocompatibility, biodegradability, and biofunctions. However, their application is often severely limited by their mechanical behavior. In this study, a tough and elastic hydrogel scaffold was prepared with hyaluronic acid (HA) and chondroitin sulfate (CS). HA and CS were conjugated with tyramine (TA) and the degree of substitution (DS) was 10.7% and 11.3%, respectively, as calculated by (1)H NMR spectra. The hydrogel was prepared by mixing HA-TA and CS-TA in presence of H2O2 and HRP. The sectional morphology of hydrogels was observed by SEM, static and dynamic mechanical properties were analyzed by Shimadzu electromechanical testing machine and dynamic mechanical thermal analyzer Q800. All samples showed good ability to recover their appearances after deformation, the storage modulus (E') of hydrogels became higher as the testing frequency went up. Hydrogels also showed fatigue resistance to cyclic compression. Mesenchymal stem cells encapsulated in hydrogels showed good cell viability as detected by CLSM. This study suggests that the hydrogels have both good mechanical properties and biocompatibility, and may serve as model systems to explore mechanisms of deformation and energy dissipation or find some applications in tissue engineering.

Cobalt and nickel nanoparticles fabricated p(NIPAM-co-MAA) microgels for catalytic applications

In this research work, multi-responsive poly(N-isopropylacrylamide-co-methacrylic acid) copolymer microgels were synthesized via emulsion polymerization in aqueous medium. Then, nickel and cobalt nanoparticles were fabricated within these microgels by in situ reduction of metal ions using sodium borohydride (NaBH4) as a reducing agent. Fourier transform infrared spectroscopy was used to characterize these microgels. The pH sensitivity of these copolymer microgels was studied using dynamic light scattering technique (DLS). DLS studies revealed that the hydrodynamic radius of these microgels increased with the increase in pH of the medium at 25°C. The catalytic activity of hybrid microgels for the reduction of p-nitrophenol (4-NP) to p-aminophenol (4-AP) was investigated by UV-visible spectrophotometery. The value of apparent rate constant of reaction was found to change linearly with catalyst dosage. The nickel-based hybrid system was found to be five times more efficient as a catalyst compared to the cobalt-based hybrid system for the reduction of 4-NP to 4-AP in aqueous medium.

Synthesis and Characterization of Gelatin-Based Magnetic Hydrogels

A simple preparation of thermoreversible gelatin-based ferrogels in water provides a constant structure defined by the crosslinking degree for gelatin contents between 6 and 18 wt%. The possibility of varying magnetite nanoparticle concentration between 20 and 70 wt% is also reported. Simulation studies hint at the suitability of collagen to bind iron and hydroxide ions, suggesting that collagen acts as a nucleation seed to iron hydroxide aggregation, and thus the intergrowth of collagen and magnetite nanoparticles already at the precursor stage. The detailed structure of the individual ferrogel components is characterized by small-angle neutron scattering (SANS) using contrast matching. The magnetite structure characterization is supplemented by small-angle X-ray scattering and microscopy only visualizing magnetite. SANS shows an unchanged gelatin structure of average mesh size larger than the nanoparticles with respect to gel concentration while the magnetite nanoparticles size of around 10 nm seems to be limited by the gel mesh size. Swelling measurements underline that magnetite acts as additional crosslinker and therefore varying the magnetic and mechanical properties of the ferrogels. Overall, the simple and variable synthesis protocol, the cheap and easy accessibility of the components as well as the biocompatibility of the gelatin-based materials suggest them for a number of applications including actuators.

Energy and environmental usage of super porous poly(2-acrylamido-2-methyl-1-propan sulfonic acid) cryogel support

Superporous and nonporous p(AMPS) cryogels and hydrogels were prepared under freezing conditions (−18 °C) and at room temperature (25 °C), respectively.

Dandelion-like cobalt hydroxide nanostructures: morphological evolution, soft template effect and supercapacitive application

A facile one-pot water bath method has been proposed to synthesize cobalt hydroxide (Co(OH)₂) nanodandelions with polyvinyl pyrrolidone (PVP) as soft template.

Highly versatile p(MAc)–M (M: Cu, Co, Ni) microgel composite catalyst for individual and simultaneous catalytic reduction of nitro compounds and dyes

Poly(methacrylic acid) (p(MAc)) microgels were synthesized by inverse suspension polymerization and used as a template for copper, nickel, and cobalt nanoparticle preparation.

Synthesis and characterization of well-defined PAA–PEG multi-responsive hydrogels by ATRP and click chemistry

Well-defined multi-responsive PAA–PEG hydrogels exhibit a unique swelling property at different pH and Ca²⁺ secondary crosslinking, and can potentially be used as stimuli responsive biomaterials.

Supramolecular hydrogels derived from cyclic amino acids and their applications in the synthesis of Pt and Ir nanocrystals

A single amino acid was used for water gelation and templating the synthesis of Pt and Ir nanocrystals.

UV-irradiation-induced templated/in-situ formation of ultrafine silver/polymer hybrid nanoparticles as antibacterial

Two types of facile approaches toward ultrafine Ag/polymer hybrid nanoparticles (NPs) within 10 nm are introduced. Template and in-situ formation method are developed by photoreduction based on inverse microemulsion (IME) polymerization of N,N-dimethylacrylamide (DMAA). The template method refers to the usage of size-varied polymeric PDMAA NPs as templates for the preparation of Ag/PDMAA hybrids with desired morphology and optical property. To avoid the self-seeding nucleation of free Ag(+) in the solution, in-situ formation method is developed by introducing AgNO3 during IME polymerization, in which product hybrids could be obtained via autoprecipitation in large scale. Additionally, the produced Ag/PDMAA hybrids show high antibacterial performance.