Carboxymethyl chitosan (CMCh) is a natural polysaccharide derivative with biodegradability, rich in active amino and carboxyl groups. It can act as a ligand to coordinate with rare earth ions, transferring absorbed energy to the central ion to sensitize its luminescence. In this paper, CMCh-Tb 3+ was prepared as a solid fluorescent probe by mixing CMCh solution with Tb 3+ . The morphology, structure and properties of CMCh-Tb 3+ were characterized and analyzed by SEM, IR and XPS, and then the chemical structure of CMCh-Tb 3+ was determined. CMCh-Tb 3+ , as a highly sensitive fluorescent sensor for detecting Cu 2+ , has a detection limit (LOD) of 27.14 nmol/L. Through characterization using fluorescence spectroscopy, ultraviolet absorption spectroscopy, and fluorescence lifetime, we further explored the mechanism of Cu 2+ fluorescence quenching, finding that this process is primarily achieved through dynamic quenching. Additionally, we discovered that glutathione (GSH) can form a strong coordination with Cu 2+ , thereby inhibiting the quenching effect of Cu 2+ on the emission intensity of CMCh-Tb 3+ and restoring its luminescence characteristics. This finding indicates that CMCh-Tb 3+ can not only serve as a fluorescence sensor for detecting Cu 2+ but also as a reversible fluorescence sensor, significantly enhancing its performance in practical applications.
Human umbilical vein endothelial cells (HUVECs) have great potential in tissue engineering, regenerative medicine, and clinical applications. There is an ever-increasing demand to provide living HUVECs and HUVECs-hydrogel constructs to end users when needed in cell-based therapy and clinical applications. However, current methods to provide living cells and their constructs are mainly continuous culture and cryopreservation, which are high-cost, labor-intensive, time-consuming and inflexible. The research about hypothermic storage of HUVECs and their hydrogel constructs is still limited. Here, we studied the cell survival of HUVECs without encapsulation (W/O Encap) or with encapsulation (alginate, alginate with carboxymethyl chitosan [CMCH]) at 4°C and 25°C during 7 days, respectively. Also, we explored the optimal CMCH concentration for hypothermic storage, which is 0.5% (w/v) at 4°C and 25°C. Moreover, we evaluated the cell attachment after hypothermic storage. Our results enable the hypothermic storage of HUVECs and HUVEC-hydrogel constructs, and facilitate their application in tissue engineering and clinical medicine.
危险品化学品经营许可证（带存储）