Interfacial Accumulation and Stability Enhancement Effects Triggered by Built-in Electric Field of SnO2/LaOCl Nanofibers Boost Carbon Dioxide Electroreduction.

Constructing a built-in interfacial electric field (BIEF) is an effective approach to enhance the electrocatalysts performance, but it has been rarely demonstrated for electrochemical carbon dioxide reduction reaction (CO2RR) to date. Herein, for the first time, SnO2/LaOCl nanofibers (NFs) with BIEF is created by electrospinning, exhibiting a high Faradaic efficiency (FE) of 100% C1 product (CO and HCOOH) at -0.9--1.1 V versus reversible hydrogen electrode (RHE) and a maximum FEHCOOH of 90.1% at -1.2 VRHE in H-cell, superior to the commercial SnO2 nanoparticles (NPs) and LaOCl NFs. SnO2/LaOCl NFs also exhibit outstanding stability, maintaining negligible activity degradation even after 10 h of electrolysis. Moreover, their current density and FEHCOOH are almost 400 mA cm-2 at -2.31 V and 83.4% in flow-cell. The satisfactory CO2RR performance of SnO2/LaOCl NFs with BIEF can be ascribed to tight interface of coupling SnO2 NPs and LaOCl NFs, which can induce charge redistribution, rich active sites, enhanced CO2 adsorption, as well as optimized Gibbs free energy of *OCHO. The work reveals that the BIEF will trigger interfacial accumulation and stability enhancement effects in promoting CO2RR activity and stability of SnO2-based materials, providing a novel approach to develop stable and efficient CO2RR electrocatalysts.

IDO2-siRNA Carried by Salmonella Combined with Nifuroxazide Attenuates Melanoma Growth.

BACKGROUND: Melanoma, a highly malignant skin cancer, is a hot topic in oncology treatment research. Nowadays, tumor immunotherapy, especially immunotherapy combined with other therapies, has attracted more and more attention. Indoleamine 2,3-dioxygenase 2 (IDO2), a ratelimiting enzyme of the tryptophan metabolism pathway in the urine of dogs with immunosuppression, is highly expressed in melanoma tissue. Additionally, IDO2 significantly inhibits the anti-tumor immunity of the body and has become a novel target of melanoma treatment. Nifuroxazide, as an intestinal antibacterial agent, was found to be able to inhibit Stat3 expression and exert an anti-tumor effect. Therefore, the present study aimed to examine the therapeutic effect of a self-designed IDO2-small interfering RNA (siRNA) delivered by attenuated Salmonella combined with nifuroxazide on melanoma- bearing mice, as well as determine its underlying mechanism. METHODS: The effect of nifuroxazide on melanoma was detected by flow cytometry, CCK-8 and colony- forming ability assays, respectively, in vitro. The plasmid of siRNA-IDO2 was constructed, and the mice-bearing melanoma model was established. After the treatment, the tumor growth and survival rate were monitored, and the morphological changes of tumor tissue were detected by HE staining. The expression of related proteins was detected by Western blotting, and the expression of CD4 and CD8 positive T cells in tumor tissue was detected by IHC and IF, and the proportion of CD4 and CD8 positive T cells in spleen was detected by flow cytometry. RESULTS: The results demonstrated that the combination therapy effectively inhibited the phosphorylation of Stat3 and the expression level of IDO2 in melanoma cells, which effectively inhibited tumor growth and prolonged the survival time of tumor-bearing mice. The mechanistic study revealed that, compared with control groups and monotherapy groups, the combination treatment group reduced the atypia of tumor cells, increased the apoptotic rate, enhanced the infiltration of T lymphocytes in tumor tissue and increased the CD4+ and CD8+ T lymphocytes in the spleen, suggesting that the mechanism may be associated with the inhibition of tumor cell proliferation, the increase of apoptosis and the enhancement of the cellular immunity. CONCLUSION: In conclusion, IDO2-siRNA combined with nifuroxazide therapy could serve a significant role in the treatment of melanoma-bearing mice, enhance the tumor immunity and provide an experimental basis for identifying a novel combination method for the treatment of melanoma clinically.