Nanophotonic Strategies for Chiral Biosensing: Nanoparticles, Metasurfaces, Magneto‐Optical, and Quantum Approaches

Chirality is fundamental in many aspects of life, from chemical reactions to biological processes. In medicine, it is central to the diagnosis of diseases such as Parkinson's and Alzheimer's, whose biomarkers are chiral and can appear in blood before symptoms emerge. In pharmaceuticals, chirality is critical: while one enantiomer of a drug may provide therapeutic benefit, its mirror image can be ineffective or toxic. Despite this importance, detecting and discriminating chiral molecules at low concentrations remains a challenge, largely due to the intrinsically weak nature of chiroptical signals. Recent advances in nanophotonics have opened promising pathways to overcome these limitations by engineering light‐matter interactions at the nanoscale. This article summarizes recent progress in chiral nanophotonic biosensing, spanning plasmonic nanoparticles, metasurfaces, magnetophotonic nanostructures, and emerging quantum‐enabled schemes. How engineered near‐fields, extrinsic and substrate‐induced chirality, and magneto‐chiroptical effects enable ultrasensitive detection of enantiomers and biologically relevant aggregates are discussed. Particular emphasis is given to quantum plasmonic biosensing, where nonclassical light and quantum tunneling effects can act together to push sensitivity toward the single‐molecule limit with unprecedented enantiomeric discrimination. With the integration of these developments, nanophotonics is poised to deliver a new generation of label‐free, highly selective chiral biosensors with far‐reaching implications for drug discovery, diagnostics, and personalized medicine.