Fluorescent carbon dots (CDs) have been synthesized via the calcination method using natural gynostemma as the precursor, without any toxic ingredients or surface passivation chemicals. CDs have a narrow size distribution, and the mean particle size is about 2.5 nm. CDs exhibit good water dispersibility and can emit intense blue fluorescence under 365 nm UV light in an aqueous solution, which can be stable in different conditions. The biotoxicity of CDs on the embryonic development of zebrafish is evaluated, the hatch rate and survival rate of embryos are around 90%, and the malformation rate is less than 10%. Because of the excellent fluorescence stability and biocompatibility, CDs can be used in zebrafish for bioimaging. In addition, the antioxidative stress property of CDs is investigated both in vitro and in vivo, and the presence of CDs can promote the mRNA expression of related genes to encode more antioxidant proteins in zebrafish. Therefore, fluorescent CDs would be a potential candidate for bioimaging and treating diseases caused by excessive oxidation damage, such as cancer, senility, and other diseases associated with aging.
Hemorrhage is common
in surgery, and excessive bleeding is the
main reason for trauma death. Effective control of bleeding is becoming
more and more important in military and civilian trauma. In this work,
oxidized cellulose nanocrystal/alginate composite films and sponges
were successfully prepared and their usages as the hemostatic materials
were investigated. Carboxyl functionalization on the cellulose nanocrystal
surface not only played a fundamental role in the structural of composites,
but also contributed to absorb plasma and stimulate erythrocytes and
platelets. Fourier transform infrared (FTIR) and X-ray photoelectron
spectroscopy (XPS) spectra showed that the carboxyl groups were successfully
introduced on the cellulose nanocrystal surface by TEMPO-mediated
oxidization. The oxidized cellulose nanocrystals (TOCN)/alginate (SA)
composites were in the presence of Ca2+ solution cross-linking.
Physical properties tests results indicated that the ultrahigh porosity
(sponge), surface homogeneity (film), water absorption ability, and
chemical stability of TOCN-30/SA composite sponge, as well as TOCN-30/SA
composite film, were all increased after ionic cross-linking, compared
to the SA sponge and film, respectively. In vitro evaluation of the
hemostatic effect, hemostatic time, and the blood loss in two injury
models exhibited that TOCN-30/SA composite sponge had the most excellent
hemostatic efficiency and could be biodegraded completely without
inflammatory reaction after three weeks. In addition, the potential
hemostatic mechanism of TOCN/SA composites was discussed.
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