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Optical biosensors have become powerful tools for bioanalysis, but most of them are limited by optic damage, autofluorescence, as well as poor penetration ability of ultraviolet (UV) and visible (Vis) light. Herein, a near-infrared light (NIR)-driven photoelectrochemical (PEC)-fluorescence (FL) dual-mode biosensor has been proposed for ultrasensitive detection of microRNA (miRNA) based on bipedal DNA walker with cascade amplification. Fueled by toehold-mediated strand displacement (TMSD), the bipedal DNA walker triggered by target miRNA-21 is formed through catalytic hairpin assembly (CHA), which can efficiently move along DNA tracks on CdS nanoparticles (CdS NPs)-modified fluorine doped tin oxide (FTO) electrode, resulting in the introduction of upconversion nanoparticles (UCNPs) on electrode surface. Under 980 nm laser irradiation, the UCNPs serve as the energy donor to emit UV/Vis light and excite CdS NPs to generate photocurrent for PEC detection, while the upconversion luminescence (UCL) at 803 nm is monitored for FL detection. This PEC-FL dual-mode biosensor has achieved the ultrasensitive and accurate analysis of miRNA-21 in human serum and different gynecological cancer cells. Overall, the proposed dual-mode biosensor can not only couple the inherent features of each single-mode biosensor but also provide mutual authentication of testing results, which opens up a new avenue for early diagnosis of miRNA-related diseases in clinic. [ABSTRACT FROM AUTHOR]

Spermidine, a natural polyamine, has been proven antioxidant function, but its pathway and mechanism of action remain unclear. Based on the oxidative stress model by 3-nitropropionic acid (3-NPA), the study explored the pathways by spermidine to rescue oxidative stress via autophagic process in goose granulosa cells by RNA-seq and RNA interference. In transcriptional regulation, in addition to KEGG pathways related to cell proliferation and differentiation, lots of KEGG pathways associated with inflammation, metabolism, and signaling were also significantly enriched in 3-NPA vs. 3-NPA + spermidine treatments. Six key genes (JUN , CD44 , KITLG , RND2 , BMP4 and KALRN) involved in spermidine-mediated anti-oxidative stress were screened. Furthermore, the experimental results showed that spermidine (80 μmol/L) significantly increased autophagic gene expression in goose granulosa cells, while EP300 -siRNA or MAP1S -siRNA also significantly increased autophagic process. The autophagic gene expressions were no difference between EP300 -siRNA and EP300 -siRNA + spermidine treatments, although spermidine significantly increased autophagic process of granulosa cells compared to MAP1S -siRNA alone. In addition, inhibition of mTOR pathway significantly increased autophagic gene expression, which was further enhanced by spermidine in combined with mTOR inhibitor. These results suggest that spermidine can alleviate oxidative stress by inducing autophagy regulated by EP300, MAP1S and mTOR as well as regulating other independent gene expressions in goose granulosa cells. • Spermidine improves oxidative stress in goose GCs by regulating autophagy and other independent gene expressions. • Transcriptomic techniques confirmed the target genes related to spermidine anti-oxidative stress by spermidine. • The autophagy pathway involved in anti-oxidative stress by spermidine was validated by gene interference analyses. [ABSTRACT FROM AUTHOR]