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The demand for artificial vascular grafts in clinical applications is increasing, and it is urgent to design a tissue-engineered vascular graft with good biocompatibility and sufficient mechanical strength. In this study, three-layer small diameter artificial vascular grafts were constructed by electrospinning. Polycaprolactone (PCL) and collagen (COL) were used as the inner layer to provide good biocompatibility and cell adhesion, the middle layer was PCL to improve the mechanical properties, and gelatin (GEL) and PCL were used to construct the outer layer for further improving the mechanical properties and biocompatibility of the vascular grafts in the human body environment. The electrospun artificial vascular graft had good biocompatibility and mechanical properties. Its longitudinal maximum stress reached 2.63 ± 0.12 MPa, which exceeded the maximum stress that many natural blood vessels could withstand. The fiber diameter of the vascular grafts was related to the proportion of components that made up the vascular grafts. In the inner structure of the vascular grafts, the hydrophilicity of the vascular grafts was enhanced by the addition of COL to the PCL, and human umbilical vein endothelial cells (HUVECs) adhered more easily to the vascular grafts. In particular, the cytocompatibility and proliferation of HUVECs on the scaffold with an inner structure PCL:COL = 2:1 was superior to other ratios of vascular grafts. The vascular grafts did not cause hemolysis of red blood cells. Thus, the bionic PCL-COL@PCL@PCL-GEL composite graft is a promising material for vascular tissue engineering.

Green fluorescent carbon dots (CDs) were prepared by one-step hydrothermal method and then modified into folic acid functionalized carbon dots (FA-CDs) and hyaluronic acid functionalized carbon dots (HA-CDs) with targeted function to study their application in breast cancer cells imaging. The microstructure of the CDs observed through TEM showed the CDs with a scale of 2.69 nm. FT-IR and XPS showed the changes of bonds and functional groups that confirmed the transformation of COOH and NH

Amphiphilic graphene quantum dots (A-GQDs) reveal prodigious potential application in bioimaging, resulting from their hydrophilic and lipophilic properties, as well as their good biocompatibility and negligible cytotoxicity. Herein, green fluorescent A-GQDs with single-layer graphene structure were prepared by one step of hydrothermal method. The A-GQDs with the average size of 3.5 nm displayed excitation-independent emission due to uniform size. A-GQDs emitted bright fluorescence on the surface of the cell membrane of MCF-7 cells when they were co-cultured with MCF-7 cells, which was similar to that of QSG-7701 cells. The water-soluble pillar[5]arene (WP5) was then incorporated on to the A-GQDs via π-π interaction and electrostatic interaction. There was different labeling imaging effect of MCF-7 and QSG-7701 cells achieved by combining the merits of WP5 and A-GQDs compared with individual A-GQDs. The synthesized composites not only had a certain enhancement in fluorescence, but also constructed a penetrating channel through the cell membrane, so that the entire cell had a distinct imaging. Therefore, these composites might be a potential candidate for applications in visualization of cell membrane and bioimaging.

Carbon quantum dots (CQDs) were prepared throught hydrothermal synthesis method. The TEM and FT-IR spectra showed the successful synthesis of CQDs and the well water solubility of CQDs. After CQDs were co-cultured with human breast cancer cells (MCF-7 cells), the cells were stained and emitted stronge green fluorescence, indicated that CQDs had a good application prospect in cancer cell imaging.