The photofixation and utilization of CO 2 via single-electron mechanism is considered to be a clean and green way to produce high-value-added commodity chemicals with long carbon chains. However, this topic has not been fully explored for the highly negative reduction potential in the formation of reactive carbonate radical. Herein, by taking Bi 2 O 3 nanosheets as a model system, we illustrate that oxygen vacancies confined in atomic layers can lower the adsorption energy of CO 2 on the reactive sites, and thus activate CO 2 by single-electron transfer in mild conditions. As demonstrated, Bi 2 O 3 nanosheets with rich oxygen vacancies show enhanced generation of •CO 2 – species during the reaction process and achieve a high conversion yield of dimethyl carbonate (DMC) with nearly 100% selectivity in the presence of methanol. This study establishes a practical way for the photofixation of CO 2 to long-chain chemicals via defect engineering.
Lack of bioactivity has seriously restricted the development of biodegradable implants in bone tissue engineering. In this study, Bone Morphogenic Protein 2 (BMP-2) was photo-immobilized on the poly(lactide-co-glycolide)/hydroxyapatite (PLGA/HA) and pure PLGA composites via photo-reactive gelatin (Az-Gel). The results demonstrate that the Az-Gel facilitates efficient and long-term immobilization of peptides on the surface of PLGA. The immobilization of Az-Gel enhanced the adhesion and proliferation of Mouse Adipose-Derived Stem Cells (ADSCs), while HA incorporation facilitated cellular osteodifferentiation. The immobilization of BMP-2 induced the osteogenesis of the ADSCs, indicated by alkaline phosphatase activity, quantitative real-time polymerase chain reaction (qRT-PCR) analysis and mineralization on the deposited substrates. Furthermore, the surface immobilization of BMP-2 could not only reduce the amount of growth factor, but also have a long-term osteoinductive effect. Therefore, it is considered that the surface modification method has a great potential for the enhancement of osteointegration of biodegradable bone implants.
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