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Precise and real-time detection of hydrogen peroxide (H2O2) is particularly necessary in pharmaceutical, industrial, and military applications because of the strong oxidability of H2O2. Here, an electrocatalytic active film with Au nanoparticles (Au NPs) embedded in a metal–organic framework (UiO-66) film was in situ prepared on the surface of an electrode for H2O2 detection. The size of Au nanoparticles and electrochemical activity of the Au nanoparticles/UiO-66 film could be controlled by manipulating the electrodeposition conditions. Since Au NPs are encapsulated into the pores of the UiO-66 film prepared in situ on a conductive substrate, aggregation of Au nanoparticles could be largely avoided, which promotes the catalytic activity and electron transfer of electrode materials. Therefore, the optimized Au nanoparticles/UiO-66 film sample presented a remarkable electrochemical response toward detection of H2O2 with an extended linear range (0.2–23 mM), a low detection limit (0.045 μM, S/N = 3), high sensitivity (329 μA mM–1 cm–2), and good stability. Furthermore, the as-prepared H2O2 sensor also displayed the advantages of excellent anti-interference performance owing to the size selectivity of the regular triangular opening channel of the UiO-66 film. Combining these advantages, the proposed sensor may open a pathway for high-performance electrochemical sensors and bioelectronics.

Because Monascus pigments (MPs) predominantly accumulate in the cytoplasm during submerged fermentation, many biotechnologies are applied to enhance the production of extracellular MPs (exMPs) to reduce the downstream processing costs. In this study, the genes monascus_7017 and monascus_8018, identified as ERG4 genes, were knocked out to disrupt the ergosterol biosynthetic pathway and enhance the production of exMPs in Monascus purpureus LQ-6. Double-deletion of EGR4 in M. purpureus LQ-6 reduced ergosterol concentration by 57.14% and enhanced exMP production 2.06-fold. In addition, integrated transcriptomic and proteomic analyses were performed to elucidate the transmembrane secretion mechanism of exMPs based on the relationship between ergosterol synthesis and membrane permeability, which revealed that several metabolic pathways were noticeably dynamic, including fatty acid degradation, amino acid metabolism, energy metabolism, carbohydrate metabolism, and transport. These findings therefore clarified the secretion mechanism of exMPs and provide a novel strategy for further enhancement of exMP production in submerged fermentation.

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