Non-toxic chitosan-based hydrogel with strong adsorption and sensitive detection abilities for tetracycline

[Display omitted] •A chitosan-based hydrogel with non-cytotoxicity and good fluorescence property.•The novel hydrogel simultaneously had effective detection and adsorption abilities.•Maximum adsorption capacity of this hydrogel for tetracycline reached 541.3 mg/g.•The hydrogel had sensitive detection ability with a detection limit of 0.12 μg/L. Antibiotics are classified as a severe cause of water contamination. Therefore, there is a great demand for an efficient and non-toxic adsorbent for antibiotics. In this study, a non-toxic chitosan-based hydrogel (CH) was developed using cellulose nanocrystals (CNs) and carbon dots (CDs). This CH had strong sorption ability (a maximum sorption capacity of 541.3 mg/g) and sensitive detection ability (linear ranges of 0.2–1.0 μg/L and 1–200 mg/L, and a detection limit of 0.12 μg/L) for tetracycline (TC). The physical and chemical structures, cytotoxicity, TC sorption and detection abilities of the CH were studied. Sorption and detection mechanisms were proposed. The study revealed that CNs offered a skeleton structure for improving the adsorption ability, and the CDs served as remarkable fluorescent probes for detecting TC with high selectivity and sensitivity.