Unique Dual-Functional and Label-Free Turn-On and Turn-Off Fluorescence Biosensor to Antibiotics Using...

Distinct from the predominantly known single-functional biosensor, dual-functional response to antibiotics by luminescent nanoribbons remains largely unexplored despite their interesting advantages in enabling self-validation through two independent fluorescence mechanisms. Antibiotic residues in food and environmental matrices pose serious health risks, which emphasizes the urgent need for highly sensitive and reliable detection strategies. Conventional analytical methods, however, often suffer from biological interferences and labor-intensive procedures, thereby underscoring demand for more efficient and robust alternatives. In this study, we focus on the detection of penicillin G (PG) and ofloxacin (OFL), representative members of the β-lactam and fluoroquinolone classes, respectively. Unlike previous reports that mainly targeted a single antibiotic class, we introduce, for the first time, a dual-functional, label-free, protein-capped platinum nanoribbon (Hb/PtNRBs) sensor capable of detecting PG via a fluorescence turn-off mechanism and OFL through a turn-on mechanism. The one-dimensional (1D) porous Pt nanoribbons, exhibiting intense blue fluorescence, were synthesized based on aggregation-induced emission (AIE) in a green, single-step process using hemoglobin (Hb) as both a reducing and capping agent. The Hb/PtNRBs display blue fluorescence with a peak centered at 442 nm (photoexcited at 325 nm) and a quantum yield of 0.25. PG detection occurs through a combination of the inner filter effect (IFE) and aggregation-caused quenching (ACQ), whereas OFL detection is attributed to a reduction-induced emission (RIE) mechanism. Under the optimized conditions, the sensor exhibited wide linear ranges of 0.2-65 μM for PG (LOD = 60 nM) and 0.2-42 μM for OFL (LOD = 45 nM). Practical applicability was confirmed in real samples, including water, cow milk, and eggs, achieving recoveries of 87.25-106.34% for PG and 86.58-120.18% for OFL. These results highlight the high sensitivity, selectivity, and potential of Hb/PtNRBs as a versatile platform for the reliable determination of PG and OFL in food and water samples.