ZnO/Cu₂O heterojunction integrated fiber-optic biosensor for remote detection of cysteine

Indium tin oxide, semiconductor nanomaterial ZnO, and Cu2O were first loaded on the surface of the optical fiber to form an optical fiber probe. Large-volume macroscopic spatial light is replaced by an optical fiber path, and remote light injection is implemented. Based on the optical fiber probe, a photoelectrochemical biosensor was constructed and remote detection of cysteine was realized. In this tiny device, the optical fiber probe not only acts as a working electrode to react with the analyte but also directs the light exactly where it is needed. Simultaneously, the electrochemical behavior of cysteine on the surface of the working electrode is dominated by diffusion-control, which provides strong support for quantitative detection. Then, under the bias potential of 0 V, the linear range of the fiber-optic-based cysteine biosensor was 0.01∼1 μM, the regression coefficient (R2) value was 0.9943. In spiked synthetic urine, the detection of cysteine was also realized by the integrated biosensor. Moreover, benefiting from the low optical fiber loss, the new structure also possesses a unique remote detection function. This work confirms that photoelectrochemical biosensors can be integrated via optical fibers and retain comparable sensing performance. Based on this property, different materials can also be loaded on the surface of the optical fiber for remote detection of other analytes. It is expected to facilitate the research on fiber-optic-based integrated biosensors and show application prospects in diverse fields such as biochemical analysis and disease diagnosis.</p

Sm3+-Mn4+ activated Sr2GdTaO6 red phosphor for plant growth lighting and optical temperature sensing

Optical temperature sensing and plant growth lighting multifunctional applications can be realized by red luminescent materials. In this paper, novel Sm3+ and Sm3+-Mn4+ activated Sr2GdTaO6 (SGTO) red phosphors for plant growth and optical temperature sensing were comprehensively analyzed. The phase, luminescence property and thermal stability of the material were tested. For PL performance, SGTO:0.075Sm3+ exhibits the maximum emission intensity in the range (560–670 nm). The emission range of SGTO:0.075Sm3+ after introducing Mn4+ is mainly dark red light emission in the range from 630 to 750 nm, and the optimum dopingconcentration of Mn4+ is determined to be 0.3 %. The emission band of SGTO:0.075Sm3+ and SGTO:0.075Sm3+, 0.003Mn4+ matches the absorption band of the plants. For optical temperature sensing properties, the relative sensitivity (Sr) and absolute sensitivity (Sa) of SGTO:0.075Sm3+, 0.003Mn4+ are 2.94

Magnetically separable electrospun BiFeO3/BiVO4 heterojunction nanofibers and the visible-light photocatalytic performance

In this paper, a novel architecture of magnetically separable BiFeO3 nanofibers were prepared by electrospinning method, and BiFeO3/BiVO4 heterojunction photocatalyst was successfully synthesized by hydrothermal method. Their structures and optical properties were characterized by X-ray diffraction, scanning electron microscopy, field emission transmission electron microscopy, the Brunner-Emmett-Teller surface areas, X-ray photoelectron spectroscopy, vibrating sample magnetometer, photoluminescence spectrum and UV–visible absorption spectroscopy. The degradation of rhodamine B by visible light irradiation for 180 min showed that the molar ratio of BiFeO3:BiVO4 was 2:1, which showed higher photocatalytic performance. The high surface area of BiFeO3:BiVO4 nanofiber heterojunction may provide more active sites for the photocatalytic reaction and promote the spatial separation of photogenerated charge, and thus show higher visible light catalytic efficiency, which is 9.5 times and 3.6 times of the single component of BiFeO3 and BiVO4 respectively. In addition, BiFeO3:BiVO4 heterojunction nanofibers are ferromagnetic and can be separated from solutions under external magnetic fields. The photocatalytic activity of the BiFeO3:BiVO4 heterojunction did not decrease significantly after five catalytic experiments, indicating that BiFeO3:BiVO4 heterojunction is stable. Free radical capture experiments show that ·OH and h+ were the main groups involved in redox reactions. Proposed photocatalyst can efficiently degrade environmental pollutants Rhodamine B under visible-light, and is easy to recover, which is expected to be used in industrial wastewater treatment