Dual-functional molecularly imprinted fluorescent probe: Sensitive detection of marine biotoxins and antiviral drugs

Saxitoxin (STX), a typical paralytic shellfish toxin, poses a serious threat to seafood safety and public health. Meanwhile, valganciclovir hydrochloride (VAL), a commonly prescribed antiviral agent, requires rigorous therapeutic drug monitoring. To overcome the limitations of current methods reliant on costly instrumentation and complex procedures, this study developed a dual-functional fluorescent probe for rapid quantification of STX and VAL via a dummy-template imprinting strategy. Using VAL as both the imprinting template and the pseudo-template for STX, 2-acrylamido-2-methylpropanesulfonic acid and sodium methallylsulfonate as functional monomers, and trimethylolpropane trimethacrylate as crosslinking agent, a highly hydrophilic molecularly imprinted polymer (MIP) was synthesized. The fluorescent probe was subsequently constructed by adsorbing rhodamine 6 G (Rh6G), enabling specific recognition and sensitive detection of both targets. The probe showed good linearity and detection performance toward STX (2–200 ng/mL, LOD: 0.84 ng/mL) and VAL (12.5–700 ng/mL, LOD: 3.70 ng/mL), along with satisfactory reproducibility (RSD ≤ 4.6%, n = 6) and stability. The imprinting factor for STX reached 4.07, and the selectivity factors against domoic acid and pectenotoxin-2 were 3.37 and 2.97, respectively. The probe was applied to quantify STX in clams and seawater samples, and VAL in mouse serum and rat plasma, yielding recoveries of 86.0%–91.4%, 82.9%–89.0%, 91.5%–97.3%, and 85.0%–91.7%, respectively. This study demonstrates the dual-functional recognition and sensitive detection capability of pseudo-template imprinting fluorescent probes, providing useful references for the rapid screening of marine biotoxins and antiviral drugs in biological matrices.