Optofluidic Sensing and Sorting of Chiral Drugs Based on Core-Shell Composite Microspheres.

Current all-optical chiral sorting approaches are ineffective for nanoscale drug molecules with weak chirality, as their faint optical response cannot maintain the chiral sorting mechanism. To overcome this physical limitation, the theoretical study proposes a core-shell composite chiral sensing microsphere, in which a drug crystal core is encapsulated by a nematic liquid crystal shell, acting as a chirality-amplifying carrier for optofluidic detection. Using a sodium ibuprofen nanocrystal as a representative weakly chiral drug, the optimal core-shell sensing structure was determined to consist of a nematic liquid crystal E7 shell with a radius of 19 μm and a sodium ibuprofen crystal core with a radius of 9.5 μm. This optimized configuration amplifies the molecular chirality parameter from 10-6 to 6.5 × 10-3 and yields the maximum transverse separation velocity of 1.19 μm/s. Hydrodynamic calculations demonstrate that when the optimized composite sensing microsphere accumulates an absolute transverse displacement greater than 19 μm within a microfluidic channel, the maximum longitudinal flow velocity of the system reaches 2.4 μm/s, satisfying the geometric threshold required for continuous sensing and sorting. This study provides a design strategy to advance optofluidic sensing and sorting systems for nanoscale chiral drugs.