Label-Free in-Situ Detection for DNA Hybridization Employing Grapefruit-Microstructured-Optical-Fiber-Based Microfluidic Whispering Gallery Mode Resonator

A whispering gallery mode (WGM) microresonator based on grapefruit microstructured optical fibers (MOFs) is proposed for in-situ DNA biosensing. The MOF microresonator has a porous structure that offers natural microfluidic channels to load microfluidic samples of volume down to 100 mu L. Moreover, the WGM mechanism greatly enhances the interaction between WGM light and liquid sample kept inside the microcavity. The inner surface of the microcavity is functionalized with poly-L-lysinemonolayer to achieve label-free binding of the single-strand probe DNA (ssDNA) through electrostatic force, and the probe immobilization aswell as DNA hybridization processes aremonitored in real time. The linear fitting of resonance wavelength shift versus DNA concentration in logarithmic scale indicates that DNA detection is available from0.01 fmol/mu L to 100 fmol/mu L. The proposed WGM microresonator biosensor possesses such desirable merits as ease of operation, fast response, label free method, and high specificity, making it a promising candidate for in-situ DNA detection and related biosensing applications.

Automated summary

The proposed WGM microresonator biosensor utilizes grapefruit MOFs to enhance interaction with microfluidic samples, functionalized with poly-L-lysine monolayer for label-free binding of ssDNA, and allows real-time monitoring of DNA processes. The sensor demonstrates linear fitting for DNA concentration detection from 0.01 fmol/µL to 100 fmol/µL, with ease of operation, fast response, label-free method, and high specificity, making it promising for in-situ DNA detection and biosensing applications.