Multicolor fluorescence digital mapping of rare-earth ion-labeled porous silica nanoprobes for the recognition of various antibiotic residues in milk.

The misuse of antibiotics not only has adverse effects on the environment but also has become a serious problem that threatens human health. However, the simultaneous, rapid, and accurate detection of various antibiotic residues remains a challenge for actual samples. Herein, a new sensing strategy was developed by using fluorescence-enhanced rare-earth ion-labeled mesoporous silica nanoprobes (MSN-COOH-Eu³⁺, MSN-COOH-Tb³⁺, and MSN-COOH-La³⁺) and their array to detect three representative antibiotics, namely, oxytetracycline (OTC), norfloxacin (NFX), and gatifloxacin (GTFX). The three rare-earth ion-labeled nanoprobes exhibited red, green, and blue fluorescence when reacting with OTC, NFX, and GTFX, respectively, because of the antenna effect of rare-earth ions or restricted conformational rotation of antibiotics. The multicolor digital imaging pattern generated from the three-nanoprobe array also enables the rapid identification of OTC, NFX, and GTFX in various combinations. Meanwhile, the linear detection ranges for OTC, NFX, and GTA were 11-30, 0-0.9,...