Photoelectrochemical determination of cardiac troponin I based on rod-like g-C3N5@MnO2 heterostructure.

Rod-like graphite carbon nitride@MnO2 (R-g-C3N5@MnO2) heterostructure was prepared by in situ self-anchored growth of MnO2 nanosheet on the surface of R-g-C3N5. The synthesized R-g-C3N5@MnO2 heterostructure as photoactive material exhibited excellent photoelectrochemical (PEC) performance, and the prepared heterostructure-aptamer probe displayed sensitive PEC response to cTnI. Therefore, the PEC method was developed to detect cTnI based on the R-g-C3N5@MnO2 heterostructure. It was found that the linear response to cTnI was in the range 0.001-30 ng/mL under optimized conditions, and the detection limit of the proposed sensor was 0.3 pg/mL. The PEC method displays stable photocurrent response up to 8 cycles and exhibited outstanding selectivity and sensitivity. The PEC method was successfully applied to detect cTnI in serum samples. The recoveries of cTnI detection in serums reach 95.5-104%, and the relative standard deviations range from 3.20 to 4.45%.

g-C3N5-dots as fluorescence probes prepared by an alkali-assisted hydrothermal method for cell imaging.

Carbon nitride materials have become one of the highly explored carbon-based nanomaterials due to their unique properties. Herein, the novel graphitic carbon nitride quantum dots (g-C3N5-dots) were synthesized using an alkali-assisted hydrothermal method. The proposed strategy was simple, time-saving and the entire synthetic process only takes 60 min. And the prepared g-C3N5-dots showed excellent dispersion and good stability in water. What is more, the g-C3N5-dots displayed bright blue fluorescence with a high quantum yield of 12%. It was found that the g-C3N5-dots exhibited peroxidase-like activity, good biocompatibility and low cytotoxicity and can be successfully applied in cell imaging. The proposed method opens a new and efficient way for the preparation of fluorescent g-C3N5-dots and facilitates g-C3N5-dots for bioimaging and related biological sensing applications.