Near-Field Imprinting of Chiral Nanolayers by Plasmon-Induced Photopolymerization for Specific and Ultrasensitive Enantioselective Detection

The ability to discriminate between molecular enantiomers is crucial for applications in biology, medicine, and asymmetric synthesis. Here, we introduce a plasmon-induced near-field photopolymerization (NFPP) approach to fabricate molecularly imprinted polymer (MIP) nanolayers in situ onto gold-coated plastic optical fibers (POF@Au). Harnessing the intense electromagnetic confinement of surface plasmon resonance (SPR), this strategy enables nanometer-precise growth of chiral recognition layers directly on the sensing surface. Using propranolol as a model compound, the resulting POF@Au@MIP sensors exhibit an ultralow limit of detection (0.34 fM) and complete enantioselectivity, showing no response to the opposite (R) enantiomer. The detection dynamics and sensitivity can be finely tuned through irradiation time, linking optical excitation to structural control. This work establishes a simple, scalable, and self-aligned route to chiral plasmonic sensors with unprecedented molecular precision.