Free Radical Polymerization of Gold Nanoclusters and Hydrogels for Cell Capture and Light-Controlled Release

Abstract

Gold nanocluster (AuNC) decorated hydrogels have attracted considerable attention as versatile biomaterials. To date AuNCs and hydrogels have mainly been mixed as independent components. Here, we report the use of AuNCs as reactive monomers in the polymerization of hydrogels. We used a free radical polymerization to copolymerize AuNCs with acrylamide and N-acryloyl glycinamide to prepare stimuli-responsive smart hydrogels. Multiple CC bonds were decorated on the surface of the AuNCs as active sites for polymerization. These CC bonds not only protected the structure of the AuNCs from oxidation by free radicals during polymerization but also covalently connected the AuNCs with the polymer chains. This structure ensured good photothermal performance of the AuNCs while preserving the thermoresponsive hydrogen bonds of polymers. Moreover, the copolymerized AuNCs acted as cross-linkers, which improved the mechanical properties of the hydrogels. These smart hydrogels had good stability, efficient photothermal conversion, and a sensitive thermoresponsive. We examined their potential for capture of MDA-MB-231 cells with hyaluronic acid as target molecules. The captured cells were released under 660 nm irradiation. This process of targeted capture and light-controlled remote release could be repeatedly applied. These results suggest that systems based on AuNCs copolymerized with hydrogels have great potential for biomedical applications.

Poly(N-isopropylacrylamide)-Based Hydrogels for Biomedical Applications: A Review of the State-of-the-Art

“…; to improve the swelling, porosity, and mechanical strength of the hydrogel system for biomedical application [ 148 ]. Several studies, e.g., PNIPAM/magnetite nanoparticles hydrogel [ 149 ], poly( N -isopropylacrylamide) hydrogel [ 150 ], PNIPAM–Ln(DPA)3 hydrogels [ 151 ], PNIPAM/gold nanocluster hydrogel [ 152 ], etc. ; have utilized free radical polymerization for PNIPAM-based hydrogel preparation to improve mechanical strength and stability.…”

Photoluminescent nanocluster-based probes for bioimaging applications

“…Au NCs have also been copolymerized with acrylamide and N-acryloyl glycinamide polymers by a free radical polymerization reaction, in order to design a stimuliresponsive hydrogel with photo-and temperature-responsive properties. This composite hydrogel could be further integrated with hyaluronic acid as targeting molecule, obtaining an integrated platform for the capture and light-controlled release of MDA-MB-231 cancer cells [99]. Finally, an interesting example of methylcellulose (MC)-based optical fibers, containing Au@BSA and Au@GSH, for biological and medical applications has been reported by Nonappa et al The presence of gold nanoclusters reinforced such solid fibers, and matched the surrounding tissue's dynamic mechanical properties with a suitable NC characteristic photoluminescence [100].…”

Conjugated Polymer-Functionalized Stretchable Supramolecular Hydrogels to Monitor and Control Cellular Behavior

“…As the essential constituent of human tissue, the extracellular matrix physically supports the morphologies of the cells by its unique three-dimensional (3D) ultrastructure. , Meanwhile, the mechanical properties of the extracellular matrix are altered during the cancer or fibrosis pathology process, which can direct cellular fate . Along with the development of tissue engineering, two-dimensional (2D) platforms or 3D scaffolds have been applied to culture cells and regulate cellular behavior. − However, the cells attached to conventional 2D platforms only proliferate on the 2D geometry, which is difficult to reproduce similar extracellular matrix microenvironment . Recently, hydrogels with 3D scaffolds have been attractive materials to mimic extracellular matrix, which paves the way for further and better research on matrix–cell interactions.…”