Controlled Structure and Properties of Thermoresponsive Nanoparticle–Hydrogel Composites

Abstract

Nanocomposite materials consisting of colloidal metal nanoparticles embedded in synthetic polymer hydrogels have attracted attention due to potential applications in catalysis, photonics, electronics, optics, and biomedicine.[1] Here we describe a method for synthesizing nanocomposite materials consisting of colloidal gold (Au) nanoparticles embedded in thermoresponsive poly(N-isopropylacrylamide) (PNIPAm) hydrogels. By incorporating thiol groups that have affinity to both Au 3+ ions and colloidal Au into the PNIPAm hydrogels, we demonstrate specific control over the size, morphology, and long-term stability of the Au nanoparticles by adjusting the concentration of thiols in the hydrogel side chains. Compared with the non-Au-containing PNIPAm hydrogels, the Au±PNIPAm nanocomposite hydrogels display remarkably different bulk properties of equilibrium swelling and thermoresponsive phase transition, which are related to the size and morphology, and possibly the surface charge, of the Au nanoparticles. One approach to synthesizing inorganic nanoparticles with potentially well-defined size and morphology is by using polymeric templates such as porous silica, [2a,b] block copolymers, [2c] dendrimers, [2d] lyotropic liquid crystals, [2e] and nonaqueous polymer resins [2f,g] and gels.

Celebrating Soft Matter's 10th Anniversary: Chain configuration and rate-dependent mechanical properties in transient networks

“…3,6,7 In each of these applications, control over gel structure and mechanics is critical to obtaining the desired gel behaviour. 8 Many such materials incorporate transient networks, where the use of physical associations as opposed to permanent chemical bonds allows the gels to respond to environmental stimuli such as temperature, 9 pH, 10 ionic strength, 11 and light.…”

Antimicrobial activity of silver nanoparticles encapsulated in poly-<em>N</em>-isopropylacrylamide-based polymeric nanoparticles

“…For example, the antimicrobial activity of Ag-impregnated nylon fibers against Staphylococcus aureus and Candida albicans was evaluated for wound dressing. 13,14 AgNPs have also been used to treat Escherichia coli because of their ability to damage bacterial cell walls. 15 Currently, AgNPs in burn ointments, wound dressings, and Ag-coated medical devices such as catheters, vascular grafts, and endotracheal tubes are used to prevent and treat bacterial infections.…”

Synthesis, Characterization, and Antibacterial Applications of Novel Copolymeric Silver Nanocomposite Hydrogels

“…22 Noteworthy, the hydrogel template methodology is that one can control the size and morphology of the nanoparticles by varying the amount of monomer, cross-linker, and functionality of gel networks. [23][24][25] Similarly, microgel formulations based on N′-isopropylacrylamide (NIPAM) in conjunction with nanoparticles are employed for electroanalytical applications. 26 Ferro-nanohydrogel composites in which magnetic nanoparticles are entrapped inside the hydrogel have been studied recently.…”

“…14 Recent trends demonstrate that the macroscopic gels are becoming most promising as templates/nanoreactors for in situ synthesis of smaller size nanoparticles and this strategy has brought up a new concept in hybrid or composite systems in chemistry and engineering science. [19][20][21] A promising antimicrobial coating of Poly (2-hydroxylethyl acrylate) (PHEA) and Poly (ethylenimine) (PEI) networks loaded with Ag nanoparticles, modified with Poly(ehyleneglycol) (PEG) was reported for biomedical and daily-life applications. 22 Noteworthy, the hydrogel template methodology is that one can control the size and morphology of the nanoparticles by varying the amount of monomer, cross-linker, and functionality of gel networks.…”