Label-free liquid crystal-based aptasensor for sensitive detection of interleukin-6 via UV-induced 4-cyano-4′-biphenylcarboxylic acid functionalization

초록

Interleukin-6 (IL-6) is a multifunctional cytokine involved in immune regulation and inflammatory diseases. Thus, its rapid and sensitive quantification is clinically important. However, conventional immunoassays often require labels, complex instrumentation, and lengthy workflows. In this study, we present a label-free liquid-crystal (LC) aptasensor that converts IL-6 binding into a robust optical response. The nematic 4-cyano-4 '-pen-tylbiphenyl was partially UV-oxidized to 4-cyano-4 '-biphenylcarboxylic acid. This oxidation introduced carboxyl groups to facilitate EDC/NHS coupling to an amino-terminated complementary oligonucleotide embedded in the LC phase. The tail region of an IL-6-specific aptamer hybridized with the surface-anchored complementary oligonucleotide (complementary strand) and disrupted homeotropic anchoring in the absence of IL-6, yielding a bright planar texture; IL-6 binding prevents hybridization and preserves a dark homeotropic texture. The percent brightness from polarized optical microscopy correlated linearly with log[IL-6] between 10 pg center dot mL-1 and 10 ng center dot mL-1, with a detection limit of 4.8 pg center dot mL-1. The aptasensor showed high specificity against common interferents and recoveries ranging from 97.22 to 100.65% in spiked human serum. This simple, rapid (<= 30 min), and low-cost platform is readily adaptable for multiplex cytokine analysis.

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