Highly photostable nanogels for fluorescence-based theranostics

A novel photo-crosslinkable nanogel is prepared from a biodegradable polymer template with intrinsic photoluminescence and high photostability. The fluorescent nanogels display excellent biodegradability and cytocompatibility owed to the facile synthesis scheme involving a solvent- and surfactant-free one-pot reaction, derived entirely from biocompatible monomers citric acid, maleic acid, L-cysteine, and poly(ethylene glycol). The resultant nanogels are less than 200 nm in diameter with a narrow size distribution and monodispersity, and demonstrate long-term structural stability in biological buffer for two weeks. To gauge potential in theranostic applications, the fluorescent nanogels were surface functionalized with biologically active RGD peptides and encapsulated with active anti-cancer drug Doxorubicin, resulting in a pH-responsive controlled drug release in acidic pH resembling tumor environments. The strong fluorescence of the nanogels enabled tracking of targeted drug delivery, showing that drug-loaded nanogels homed into the cytoplasmic regions of prostate cancer cells to significantly induce cell death. These photo-crosslinkable and biodegradable nanogels pose as a strong candidate for theranostic medicine, demonstrating versatile functionalization, high stability in biological buffers, and capacity for real-time fluorescence-based monitoring of targeted drug delivery

Scaffold Sheet Design Strategy for Soft Tissue Engineering

Creating heterogeneous tissue constructs with an even cell distribution and robust mechanical strength remain important challenges to the success of in vivo tissue engineering. To address these issues, we are developing a scaffold sheet tissue engineering strategy consisting of thin (~200 μm), strong, elastic, and porous crosslinked urethane- doped polyester (CUPE) scaffold sheets that are bonded together chemically or through cell culture. Suture retention of the tissue constructs (four sheets) fabricated by the scaffold sheet tissue engineering strategy is close to the surgical requirement (1.8 N) rendering their potential for immediate implantation without a need for long cell culture times. Cell culture results using 3T3 fibroblasts show that the scaffold sheets are bonded into a tissue construct via the extracellular matrix produced by the cells after 2 weeks of in vitro cell culture