Photoelectrochemical immunosensor for HER2 detection based on BiVO4-Bi2S3 heterojunction as photoactive material and CdS as signal probe.

A sandwiched photoelectrochemical (PEC) sensor was developed for sensitive detection of human epidermal growth factor receptor 2 (HER2) based on BiVO4-Bi2S3 heterojunction as the photoelectric material accompanied with magnetic nanoparticles for enrichment of HER2 and CdS for signal amplification. The in situ generation of Bi2S3 on the surface of BiVO4 forming a BiVO4-Bi2S3 heterojunction is more conducive to the transit of electron-hole pairs. Antibody-modified MNs are utilized to capture and separate HER2 from samples. After forming a sandwich immune structure, under illumination, the photocurrent shows an increasing trend with the increment of HER2 concentration. The PEC immunosensor displays a good linear concentration range between 1.00 and 1.00 × 103 pg·mL-1 and a low limit of detection down to 0.680 pg·mL-1 (S/N = 3) for HER2 under a bias voltage of 0.1 V (vs. Ag/AgCl electrode). Furthermore, the sensor was successfully applied to detect HER2 in serum samples with recoveries that ranged between 96.1 and 114% with RSDs between 1.3 and 5.9%.

Anion exchange and successive ionic layer adsorption and reaction-assisted coating of BiVO4 with Bi2S3 to produce nanostructured photoanode for enhanced photoelectrochemical water splitting.

Photoelectrochemical water splitting is an environmentally benign way to store solar energy. Properties such as fast charge recombination and poor charge transport rate severely restrict the use of BiVO4 as a photoanode for photoelectrochemical water splitting and many attempts were made to improve the current performance limit of the photoanode. To address these disadvantages, a highly efficient BiVO4/Bi2S3 heterojunction was fabricated applying facial anion-exchange (AE) and successive ionic layer adsorption and reaction (SILAR). The deposition of Bi2S3 on BiVO4 nanoworms by both AE and SILAR was confirmed through morphological, structural, and optical analyses. The morphological analysis indicated that Bi2S3 grown through SILAR has relatively more crystalline-amorphous phase boundaries than Bi2S3 generated using the anion-exchange method. The highest photocurrent density was observed for the SILAR-coated Bi2S3 on BiVO4, which is three times the value of the pristine BiVO4 measured under 1 sun illumination (100 mW cm-2 with Air mass (AM) 1.5 filter) in a 0.5 M Na2SO4 electrolyte at 1.6 V vs. RHE. In addition, the deposition of Bi2S3 through AE results in a twofold higher photocurrent density compared to uncoated BiVO4. The comparison of the two cost-effective AE and SILAR methods to deposit Bi2S3 on BiVO4 showed a negative shift in the flat band Mott-Schottky values, which coincides with the drifted onset potential values of the current density-voltage (J-V) curve. Furthermore, photoelectrochemical impedance spectroscopy (PEIS) analyses and band alignment studies revealed that SILAR-grown Bi2S3 creates an effective heterojunction with BiVO4, which leads to an efficient charge transfer.

BiVO4@Bi2S3 Heterojunction Nanorods with Enhanced Charge Separation Efficiency for Multimodal Imaging and Synergy Therapy of Tumor.

Despite malignant tumors being one of the most serious diseases threatening human health and living quality, exploring theranostic agents for highly effective tumor diagnosis and treatment is still full of challenges. Herein, we demonstrate the design and preparation of Tween-20-modified BiVO4@Bi2S3 heterojunction nanorods (HNRs) for multimodal computed tomography (CT)/photoacoustic (PA) imaging and radiotherapy (RT)/radiodynamic therapy (RDT)/photothermal therapy (PTT) synergistic therapy. Benefiting from the high X-ray attenuation coefficient of Bi, BiVO4@Bi2S3 HNRs exhibit a sensitive CT imaging capacity and radiation enhancement effect during RT. Meanwhile, the strong NIR absorption of Bi2S3 endows BiVO4@Bi2S3 HNRs with an excellent PA imaging and photothermal transformation capacity. More importantly, by taking advantage of the type II band alignment between BiVO4 and Bi2S3, an extra internal electric field is established to accelerate the separation of X-ray-induced electrons and holes in BiVO4@Bi2S3 HNRs, resulting in the realization of highly effective X-ray-induced RDT. Because the in vitro and in vivo experiments have verified that the RT/RDT/PTT synergistic therapeutic efficacy is greatly superior to any single treatment, it is believed that our BiVO4@Bi2S3 HNRs can be used as the multifunctional nanotheranostic platform for malignant tumor theranostics.

Comprehensive Study of the Growth Mechanism and Photoelectrochemical Activity of a BiVO4/Bi2S3 Nanowire Composite.

A BiVO4/Bi2S3 composite comprising Bi2S3 nanowires on top of a BiVO4 film was prepared via hydrothermal reaction. Because additional Bi3+ ions were not delivered during the reaction, BiVO4 served as the Bi3+ ion source for the development of Bi2S3. A detailed growth mechanism of the nanowire was elucidated by an analysis of the concentration gradient of Bi3+ and S2- ions during the reaction. The in situ growth was followed by the etching of BiVO4 to Bi3+ and VO43- ions and regrowth to Bi2S3, which resulted in the rapid evolution of nanowires on the BiVO4 substrate. The fabricated BiVO4/Bi2S3NW composite exhibited an improved photoelectrochemical activity compared to other Bi2S3 samples. The improved efficiency was mainly attributed to both improved charge separation and effective adhesion obtained by the in situ growth.