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Abstract A novel p-type semiconductor-based cathodic "signal-on" photoelectrochemical (PEC) aptasensor was proposed for highly sensitive and selective detection of chloramphenicol (CAP). The photocathode was fabricated with hierarchical porous flower-like Bi-BiOI@C composite synthesized via a one-pot solvothermal method using glucose as both green reductant and carbon precursor. Due to the surface plasmon resonance (SPR) effect of Bi and high-conductivity of carbon, the composite exhibited an enhanced cathodic photocurrent as compared with pure BiOI or Bi-BiOI. When CAP-binding aptamer was immobilized as recognition element on Bi-BiOI@C modified electrode, a cathodic PEC aptasensor showing specific "signal-on" response to CAP was constructed. Some influencing factors such as coating amount of Bi-BiOI@C suspension, applied bias potential, and aptamer concentration were studied. Under the optimum conditions, the cathodic photocurrent of the constructed PEC aptasensor increased linearly with CAP concentration from 2 to 250 nM, with a detection limit (3S/N) of 0.79 nΜ. The proposed sensor was successfully applied to the determination of CAP in pharmaceutical tablet, eye drop and lake water samples. Highlights • Cathodic "signal-on" photoelectrochemical (PEC) aptasensing strategy is developed. • Flower-like Bi-BiOI@C composite is synthesized via a one-pot solvothermal process. • Glucose is used as both green reductant and carbon precursor for composite synthesis. • Bi-BiOI@C composite exhibits an improved performance for cathodic PEC sensing. • Bi-BiOI@C is utilized to construct cathodic PEC aptasensor for CAP detection. [ABSTRACT FROM AUTHOR]

In this work, a self-powered sensor was proposed for simultaneous detection of two typical steroid hormones, namely cortisol (COR) and progesterone (P4). A tri-channel photofuel cell (PFC) consisting of three spatially resolved SnS 2 @SnO 2 photoanodes and one Pt cathode was designed to generate the electricity to drive the sensing process under the control of a multiplex switch. Among three photoanodes, one served as the control, while the other two were modified with COR-binding or P4-binding aptamer to respond specifically to the COR or P4 target. The ratios of the inhibited PFC output from aptamer-immobilized photoanodes to the reference signal from the control photoanode were utilized for simultaneous detection of COR and P4. The results showed that the developed self-powered sensor exhibited broad concentration ranges toward targets, with COR concentration ranging from 1 nM to 1000 nM and P4 concentration ranging from 1 nM to 500 nM. The detection limits for COR and P4 were calculated to be 0.88 nM and 0.52 nM, respectively. Moreover, the proposed sensing platform demonstrated high selectivity, good reproducibility, and high stability. Finally, the sensor was successfully applied to the simultaneous determination of COR and P4 in a human female serum sample. [ABSTRACT FROM AUTHOR]

With the advent of flexible electronics and sensing technology, hydrogel-based flexible sensors have exhibited considerable potential across a diverse range of applications, including wearable electronics and soft robotics. Recently, advanced machine learning (ML) algorithms have been integrated into flexible hydrogel sensing technology to enhance their data processing capabilities and to achieve intelligent perception. However, there are no reviews specifically focusing on the data processing steps and analysis based on the raw sensing data obtained by flexible hydrogel sensors. Here we provide a comprehensive review of the latest advancements and breakthroughs in intelligent perception achieved through the fusion of ML algorithms with flexible hydrogel sensors, across various applications. Moreover, this review thoroughly examines the data processing techniques employed in flexible hydrogel sensors, offering valuable perspectives expected to drive future data-driven applications in this field. [ABSTRACT FROM AUTHOR]

The progesterone (P4) level in body fluids can act as an indicator for early pregnancy diagnosis and offers insight into mammalian somatic function. In this work, we designed an antibody-aptamer based sandwich assay as a cathodic photoelectrochemical (PEC) biosensor for P4 detection. The composites of carbon dots and graphene oxide (CDs-GO) with favorable cathodic photocurrent response were used as photoactive materials on which the antibody (Ab) of P4 was immobilized. Meanwhile, high affinity truncated P4 aptamer was immobilized on Au–CuO–Cu 2 O to act as a bioconjugate. When P4 was present, the aptamer-Au-CuO-Cu 2 O bioconjugate could amplify the cathodic photocurrent of CDs-GO modified electrode through Ab-P4-aptamer interactions. Under optimum conditions, the cathodic photocurrent of the constructed PEC biosensor was found to increase linearly with P4 in a wide concentration range from 0.5 nM to 180 nM, with a low detection limit (3S/N) of 0.17 nΜ. The proposed cathodic PEC sensing platform demonstrated high selectivity, satisfying reproducibility, good stability. The sensor was successfully applied in the determination of P4 in human serum samples. • An antibody-aptamer based sandwich assay for progesterone is proposed. • A cathodic photoelectrochemical biosensor with sandwich structure is designed. • Carbon dots-graphene oxide composites are used as photocathodic materials. • Aptamer-conjugated photoactive nanoparticles provide a signal-on sensing strategy. [ABSTRACT FROM AUTHOR]

CdS–In 2 S 3 heterojunction with enhanced photoelectrochemical (PEC) performance was synthesized to construct dual-mode visible light-induced biosensors for highly sensitive and selective detection of bleomycin (BLM). Due to improved absorption in the visible region and suppressed recombination of electron-hole pairs in the heterojunction, CdS–In 2 S 3 composite exhibited enhanced photocurrent response under visible light illumination. Using CdS–In 2 S 3 as photoactive materials and BLM-binding aptamer as recognition element, a PEC aptasensor displaying a declined photocurrent response to BLM was facilely constructed, which was linear to BLM concentration in the range of 5.0–250 nM. On the other hand, the CdS–In 2 S 3 photoanode was employed to construct a photofuel cell (PFC). In such a PFC, the oxidation of water on CdS–In 2 S 3 photoanode under visible light illumination and the reduction of oxygen on Pt cathode led to the generation of electricity. When BLM-binding aptamer was immobilized on CdS–In 2 S 3 photoanode, the output power of the PFC was inversely proportional to the logarithm of BLM concentration from 10 to 250 nM, offering a visible light-induced self-powered sensing platform for BLM detection. Both of the proposed sensors showed high selectivity, good reproducibility and high stability. They were successfully applied to the determination of BLM in human serum samples. • Iron-free photoelectrochemical sensor for bleomycin detection is developed firstly. • Photofuel cell-based self-powered aptasensor for bleomycin detection is proposed. • CdS–In 2 S 3 heterojunction is used as photoactive materials for sensor construction. • CdS–In 2 S 3 composite is successfully prepared by in situ formation of CdS on In 2 S 3. [ABSTRACT FROM AUTHOR]