A sensitive fluorescent sensor based on terpyridine@Zn2+-modified mesoporous silica for the detection of sulfonamide antibiotics

Abstract

The sensitive detection of sulfonamide antibiotic (SA) residues is of great significance to ecosystems and public health. To overcome the defect of poor water dispersion stability and low sensitivity of SA detection systems, a terpyridine@Zn²⁺-modified mesoporous silica, denoted ATpy@Zn-SBA-15, was developed and applied as a highly sensitive and quickly responsive fluorescent sensor for the detection of SAs in tap water and milk. Terpyridine, with three pyridine groups, can form a stable complex with Zn²⁺. The Zn²⁺ in terpyridine@Zn²⁺ provides binding sites to recognize SAs such as sulfathiazole (STZ) by forming conjugates between ATpy@Zn-SBA-15 and STZ, thus facilitating energy transfer from the organic functional groups of ATpy@Zn-SBA-15 to STZ, resulting in efficient changes in fluorescence spectra. When the concentration of SAs such as STZ increased, the fluorescence emission intensity of ATpy@Zn-SBA-15 suspensions at 429 nm gradually decreased. ATpy@Zn-SBA-15 exhibited relatively low detection limits of 0.17, 0.63, 0.52, 0.57 and 0.54 μM for STZ, sulfamethizole, sulfachlorpyridazine, sulfamerazine and sulfamethoxypyridazine, respectively. Compared with the material without Zn²⁺, ATpy@Zn-SBA-15 displayed remarkably enhanced SA sensitivity, which demonstrated that introducing the Zn²⁺ sites played a crucial role for both specific recognition of SAs and fluorescence response signals. Prominently, this proposed strategy can be applied for detecting other antibiotics by varying the organic functional groups and metal sites.