A Fluorescence Resonance Energy Transfer (FRET) Biosensor Based on Zinc Oxide (ZnO) and Porphyrin for the Detection of Trimethylamine in Aquatic Products

Hierarchical zinc oxide (ZnO) nanomaterials have been successfully synthesized using a biotemplated method. The morphology and structure of the produced samples were characterized by means of SEM, TEM, XRD, FTIR, etc. The result showed that hierarchical ZnO nanomaterial retained the porous network structure of the template. Trimethylamine (TMA) in aquatic products was effectively detected by a fluorescence resonance energy transfer (FRET)–based molecular sensor using ZnO as energy donors and tetrasodium-meso-tetra(4-sulfonatophenyl) porphine dodecahydrate (TPPS) as energy acceptors. The FRET efficiency was reduced by the addition of TMA, due to the combination between TPPS and TMA. The fluorescence intensity of ZnO (donor) would decrease gradually with the increasing concentration of TMA. Under the optimal conditions, a linear correlation was established between the fluorescence intensity ratio I TPPS / I ZnO and the concentration of TMA in the range of 2.67 × 10 −11 –6.67 × 10 −6  mol/L and 1.33 × 10 −5 –6.67 × 10 −4  mol/L with a detection limit of 7.51 × 10 −12  mol/L. The proposed method was successfully applied to the determination of TMA in real fish samples with satisfactory results.