Multifunctional semiconducting carbon nitrides enabling sequential fluorescent sensing of telomerase activity and internal self-checking.

Improving the detection reliability of biosensors is essential but challenging. The dual-signal self-checking function is useful for the development of reliable biosensors; however, it inevitably increases the complexity of the sensing system. Thus, biosensors with intrinsic self-checking functions that do not require additional chemicals, specific sensor assemblies, and/or instruments are highly desirable. Herein, integrating the ability of fluorescence detection and photodegradation by carbon nitride nanosheets (CNNS), a biosensor with a self-checking function for sensitive telomerase activity detection was constructed. Acriflavine (AF) was screened from various dyes to form the most effective CNNS-AF donor-acceptor (D-A) interfaces by experiments and density functional theory (DFT) calculations, considering spectral match, electrostatic interaction, and non-covalent stacking. As a result, the proposed fluorescence biosensor not only showed highly sensitive detection of telomerase activity but also had an internal self-checking function by photodegradation of AF via continuous excitation and measurement of recovered fluorescence. This study sheds light on CNNS-based D-A interfaces with synergistic fluorescence detection and photocatalysis-induced self-checking properties for future clinical diagnosis with high sensitivity and reliability. • A biosensor with an intrinsic self-checking function for sensitive telomerase activity detection was constructed. • The self-checking function did not require additional chemicals, specific sensor assemblies, and/or instruments. • Carbon nitride-acriflavine was selected as the most effective donor-acceptor pair by experiments and DFT calculations. • Donor-acceptor fluorescent sensing and photocatalyst-based self-checking was coupled using carbon nitrides of multi-roles. [ABSTRACT FROM AUTHOR]