A porous hydrogen-bonded organic framework for sensitive and highly selective fluorescence sensing of carcinoid biomarkers

Serotonin (5-hydroxytryptamine, 5-HT) as a vital neurotransmitter, is also a vital discriminating biomarker for the detection of carcinoid tumors. Monitoring the concentration of 5-HT in blood is of great significance for the progression of biological changes in patients with carcinoid tumors. Based on the organic molecule 2,4,6-Tris (4-carboxyphenyl) aniline (BTB-NH2), a hydrogen-bonded organic framework (HOF) material HOF-BTB-NH2 was successfully constructed. The BET surface area of HOF-BTB-NH2 is 316 m2/g. The porous structure and the excellent luminescence properties enable HOF-BTB-NH2 to be a superior fluorescence sensor for sensitive detection of 5-HT with a fast response time of 30 s. The detection limit is as low as 1.21 μM, and it exhibits high selectivity in potential serum interfering substances. The molecule size of 5-HT (11.9 × 8.3 × 4.0 Å) was much smaller than the average pore diameter of the HOF (26 Å), thus the 5-HT can fully diffuse into the pores and closely interact with the HOF, enabling the possible existence of competitive absorption and Dexter mechanism for the fluorescence quenching. Moreover, it can also be prepared into fluorescent hydrogels and fluorescent films to realize visual sensing of 5-HT. In addition, the detection of 5-HT in biological serum samples was also applied with satisfactory recovery (101.2%–102.8%). As far as we known, the luminescent HOF-BTB-NH2 is the first example of HOF materials for the detection of biomarker 5-HT with high sensitivity and selectivity. This work contributes to the development of luminescent HOF materials and HOF-based hydrogels/films as novel sensing platform with superior sensitivity, selectivity and fast response towards practical chemical sensing applications.