DNA Sensing with Whispering Gallery Mode Microlasers

Nucleic acid sensing is crucial for advancing diagnostics, therapeutic monitoring and molecu-lar biology research, by enabling the precise identification of DNA and RNA interactions. Here, we present an innovative sensing platform based on DNA-functionalized whispering gallery mode (WGM) microlasers. By correlating spectral shifts in laser emission to changes in refractive index, we demonstrate real-time detection of DNA hybridization and structural changes. The addition of gold nanoparticles to the DNA strands significantly enhances sensi-tivity, and labeling exclusively the sensing strand or a hairpin strand eliminates the need for secondary labeling of the target strand. We further show that ionic strength influences DNA compactness, and we introduce a hairpin-based system as a dual-purpose sensor and con-trolled release mechanism for potential drug delivery. This versatile WGM-based platform of-fers promise for sequence-specific nucleic acid sensing, multiplexed detection, and in vivo ap-plications in diagnostics and cellular research.