Highly-sensitive liquid crystal biosensor based on DNA dendrimers-mediated optical reorientation.

A novel highly-sensitive liquid crystal (LC) biosensing approach based on target-triggering DNA dendrimers was developed for the detection of p53 mutation gene segment at the LC-aqueous interface. In this study, the mutant-type p53 gene segment was the target to trigger the formation of DNA dendrimers from hairpin DNA probes by hybridization chain reaction, and the latter as a 'signal enhancement element' further induced the LC reorientation from tilted to homeotropic alignment, resulting in a corresponding optical changes of LC biosensors from birefringent to honeycombed textures or dark framework. The distinct optical reorientational appearances can serve as a characteristic signal to distinguish target concentrations ranging from 0.08 nM to 8 nM. Moreover, these optical phenomena suggest that the LC reorientation is related to the electric-dipole coupling between the adsorbed DNA and LC molecules, the conformational constraints of DNA and the internal electric field induction upon hybridization. This label-free LC biosensing strategy can open up a new platform for the sensitive detection of specific DNA sequences and enrich the application scope of an LC biosensing technique.