Du Liting,Li Yu,Li Shouchun,Li Haiying,Liu Li,Cheng Yali,Duan Haojie
The hierarchical porous and nonporous SnO 2 microflowers was successfully synthesized by a simple hydrothermal method and followed by calcination procedure. The microstructure and morphology of the product were characterized by X-ray diffraction, energy dispersive X-ray spectroscopy, and scanning electron microscopy (SEM). The SEM images display that the prepared SnO 2 is a microflower composed of countless thin sheets, and each of the sheets covered in a series of porous by calcining at 500 °C. Nevertheless, there is no porous when it treated at 400 °C. The results of comparison show that the hierarchical porous SnO 2 microflowers (HPSM) sensors possess a preferable gas-sensing property. The response of HPSM sensors to 100 ppm ethanol is 205.6 at the optimum operating temperature 240 °C. Which sensitivity is almost 3.9 higher than the hierarchical nonporous SnO 2 microflowers (HNSM) (52.9). Meanwhile, the response and recovery times of HPSM (HNSM) are 3 s (3 s) and 45 s (145 s) to 100 ppm ethanol, respectively. What’s more, the minimum concentration of ethanol that we can detect is 0.1 (1.0) ppm, and the response value is 1.9 (2.0). At last, both HPSM and HNSM own a good selectivity.
A unique hierarchical mesoporous SnO2 microflower was utilized for the fabrication of an immunosensor. The modified nitrogen-doped carbon quantum dots (NCQDs) improved the photoelectrochemical (PEC) activity of the SnO2, and contributed to the in situ assembly of Bi2S3 nanoparticles on the surface of the SnO2 materials. Under the stimulation of visible light and ascorbic acid as an efficient electron donor, the NCQDs and Bi2S3 co-sensitized mesoporous SnO2 microflower (SnO2/NCQDs/Bi2S3) modified ITO electrode exhibited an excellent photoelectric signal arriving at around 150 μA. Moreover, a novel label-free PEC sensor based SnO2/NCQDs/Bi2S3 composite was constructed, which enabled the ultrasensitive detection of N-terminal pro-B-type natriuretic peptide (NT-proBNP). The photocurrents decreased linearly with the logarithm of NT-proBNP concentration in the range of 0.01–50 ng mL−1 with a detection limit of 3.7 pg mL−1 (S/N = 3). Furthermore, the novel PEC immunosensor showed perfect selectivity, good stability and reproducibility, which suggest promising applications in the sensing and clinical diagnosis of cardiac disease.
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