超手性场,由手性等离子体结构支持,已通过增强的手性光-物质相互作用显示了手性分子传感的出色性能。然而,这种传感能力不能完全揭示分子的手性起源,因为分子的手性响应与手性等离子体纳米结构的手性响应交织在一起,可以通过使用等离子体外消旋混合物来排除。这种等离子体外消旋混合物是不容易实现的,因为它通常需要复杂的制造和昂贵的仪器,其结构细度受到制造精度的限制。这里,我们展示了痕量手性分子检测与等离子外消旋阵列通过直接激光写入与矢量光束,这很容易,成本效益高,高度可控。外消旋阵列没有固有的圆形微分散射,而是一个大的局部超手性场,这反映了手性分子的内在手性特征。它们进一步用于区分苯丙氨酸的对映体,检出限(LOD)为10.0±2.8μM,比常规圆二色性光谱的LOD小一个数量级。等离子体外消旋阵列提供的强局部超手性场启发了卓越的传感平台的设计,这为生物医学检测和对映选择性药物开发提供了有希望的应用。
Superchiral fields, supported by chiral plasmonic structures, have shown outstanding performance for chiral molecule sensing via enhanced chiral light-matter interaction. However, this sensing capability cannot fully reveal the chiral origin of the molecules as the chiroptic response of the molecules is intertwined with the chiroptic response of the chiral plasmonic nanostructures, which can potentially be excluded by using a plasmonic racemic mixture. Such a plasmonic racemic mixture is not easily attainable, as it normally requires complex fabrication and expensive instrumentation, whose structural fineness is limited by the fabrication precision. Here, we demonstrate trace-amount chiral molecule detection with plasmonic racemic arrays fabricated by direct laser writing with vector beams, which is facile, cost-effective, and highly controllable. The racemic arrays present no inherent circular differential scattering but a large local superchiral field, which reflects the intrinsic chiral features of the chiral molecules. They are further applied to discriminate enantiomers of phenylalanine with a limit of detection (LOD) of 10.0 ± 2.8 μM, which is an order of magnitude smaller than the LOD of conventional circular dichroism spectroscopy. The strong local superchiral field provided by the plasmonic racemic arrays enlightens the design of a superior sensing platform, which holds promising applications for biomedical detection and enantioselective drug development.