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The rapid recombination of carriers on plasmon metal nanoparticles leads to relatively low efficiency of traditional photocatalysts. The combination of a metal and a semiconductor allows to the separation of hot electrons and holes to improve photocatalytic efficiency. In this study, Au nanoparticles were integrated with semiconductor TiO2 nanoparticles of different sizes to improve the photocatalytic activity. Various techniques have been developed to study the mechanism of catalytic activity, the significance of band bending in the space-charge region within metal–semiconductor nanocomposites, and the built-in electric field. The results provide theoretical and experimental evidence for the design of a high-performance surface plasmon resonance (SPR) photocatalyst. To reveal the interface band structure, surface-enhanced Raman spectroscopy (SERS) was employed to analyze the band structure of the TiO2–metal composites. This approach was based on the electrochemical Stark effect and a molecular probe strategy, combined with X-ray photoelectron spectroscopy (XPS), Electrochemical impedance spectroscopy (EIS), and other techniques at the molecular level. The results demonstrated that charge transfer occurred spontaneously between the Au nanoparticles and TiO2, and that the TiO2–metal interface constitutes a Schottky barrier. Moreover, the size of the TiO2 nanoparticles affects the degree of band bending. Optimal state matching was achieved with TiO2 (60 nm)–Au, improving the photocatalytic activity of the nanocomposite. The photocatalytic coupling reaction of p-aminothiophenol (PATP) acted as a probe to study the catalytic performance of TiO2–metal nanocomposites. The results revealed that the introduction of TiO2 improves the SPR catalytic activity of Au, mainly through the efficient separation of electrons and holes at the TiO2–metal interface.

Zuojin capsule (ZJC), a classical prescription, is outstanding in improving the conditions of patients with gastrointestinal diseases and colorectal cancer (CRC). Although ZJC has multi-ingredient and multi-target characteristics, its pharmacological effect on colorectal cancer and the underlying mechanism remain unclear.Here, the activity of ZJC against CRC was evaluated by the experiments with CRC cells and HCT-116 xenografted mice. The key genes of CRC were obtained from the cancer genome atlas (TCGA). The genes potentially targeted by ZJC were collected from traditional Chinese medicine systems pharmacology (TCMSP) database. The underlying pathways related to selected targets were analyzed through gene ontology (GO) and pathway enrichment analyses. Western blot (WB), cellular thermal shift assay (CETSA), molecular docking and quantitative real-time PCR (QRT-PCR) were carried out to confirm the validity of the targets.In vitro and in vivo results indicated that ZJC may inhibit CRC cells and tumor growth. The network pharmacological analysis indicated that 22 compounds, 51 targets and 20 pathways were involved in the compound-target-pathway network. Our results confirmed that ZJC inhibited cycle progression, migration and induced apoptosis by targeting candidate genes (CDKN1A, Bcl2, E2F1, PRKCB, MYC, CDK2, and MMP9). We found that ZJC could directly change the protein level by regulating the protein stability and transcriptional activity of the target.In summary, combined network pharmacology and biological experiments proved that the main ingredients of ZJC such as quercetin, (R)-Canadine, palmatine, rutaecarpine, evodiamine, beta-sitosterol and berberine can target CDKN1A, Bcl2, E2F1, PRKCB, MYC, CDK2 and MMP9 to combat colorectal cancer. The results of this study provide a basic theory for the clinical trials of Zuojin Capsules against colorectal cancer.