Dezhi Yang,Qiulan Li,Sai Kumar Tammina,Zhe Gao,Yaling Yang
The construction of highly efficient nanozyme activities in a simple means is vital for the wide biological and chemical applications. Present work describes a Cu-based carbon dots (Cu-CDs) with oxidase- and peroxidase-like activity for the catalytic oxidation of o -phenylenediamine (OPD) at neutral pH. The peroxidase-like activity of Cu-CDs was finely tuned and enhanced by changing the ascorbic acid (AA) content and reduction temperature to increase the Cu + content. The oxidation of OPD was significantly accelerated by the addition of Fe 2+ ions (i.e., Cu-CDs + Fe 2+ /H 2 O 2 system) and presented a smaller K m (Michaelis constant) and a higher V max (maximum rate) than horseradish peroxidase (HRP) at the same mass concentration. The Cu-CDs with oxidase- and peroxidase-like activities could catalyze to produce the superoxide radical ( · O 2 - ) and hydroxyl radical (·OH) in the system. Interestingly, the catalytic oxidation of OPD to 2,3-diaminophenazine (DAP) could be inhibited by Cr(III) ions in Cu-CDs + Fe 2+ /H 2 O 2 system. Therefore, a new fluorescent detection strategy was developed for the detection of Cr(III) with the linear range of 0.2−100 μM, and the detection limit of 36 nM (S/N = 3). This work provides new insight into the mechanism and kinetics of low-valence copper–carbon dots peroxidase-like and Fenton co-catalyst system.
Biomaterials with dual functions of osteoimmunomodulation and bone repair are very promising in the field of orthopedic materials. For this purpose, we prepared a copper-based carbon dots (CuCDs) and doped it into oxychondroitin sulfate / poly-acrylamide hydrogel (OPAM) to obtain a hybrid hydrogel (CuCDs/OPAM). We evaluated its osteoimmunomodulatory and bone repair properties in vitro and in vivo. The obtained CuCDs/OPAM exhibited good rBMSCs-cytocompatibility and anti-inflammatory properties in vitro. It also could effectively promote rBMSCs differentiation and the expression of osteogenic differentiation factor from rBMSCs under an inflammatory environment. Moreover, CuCDs/OPAM could induce macrophage phenotype switching (from M1-type macrophages to M2-type macrophages) in vivo which was beneficial to anti-inflammatory and present a good osteoimmunomodulation capability to induce a bone immune microenvironment to promote the differentiation of rBMSCs. In conclusion, CuCDs/OPAM hydrogel has dual functions of osteoimmunomodulatory and bone repair, and is a promising bone filling and repair material.
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