Fluorescent dextran-based nanogels: efficient imaging nanoprobes for adipose-derived stem cells

For the efficient tracking of adipose-derived stem cells (ADSCs), nano-sized probes provide convenient platforms and have many advantages over the induction of reporter genes. Despite their great potential for various applications, investigations on macromolecular nanogels acting as stem cell tracking probes remain limited due to the difficulties encountered with synthesizing macromolecular nanogels with controllable diameters and surface charges. In this report, we describe a self-assembly assisted (SAA) methodology for the efficient preparation of fluorescent dextran-based nanogels as ADSC imaging nanoprobes. Through a three step procedure involving the fabrication of dextran-based nanogels, the conjugation of fluorescent molecules with the nanogels, and the surface modification of the fluorescent nanogels, novel fluorescent nanogels with various diameters ranging from 165 to 241 nm and surface potentials ranging from −10 to 10 mV were fabricated. The feasibility of these nanogels for ADSC imaging applications was also investigated. We demonstrate that negatively charged nanogels provide effective ADSC imaging without requiring any cell-uptake enhancers. Additionally, we observed that the capabilities of these nanogels to provide ADSC imaging is closely related to both their size and surface charge. Our study suggests that the fluorescent nanogels generated by the SAA approach have great potential for ADSC imaging applications due to their excellent cell imaging capabilities and low cytotoxicity.