Simple, rapid and sensitive detection of Parkinson's disease related alpha-synuclein using a DNA aptamer assisted liquid crystal biosensor

Alpha-synuclein (alpha S) has been proposed as a potential biomarker for the diagnosis of Parkinson's disease (PD). However, the detection of alpha S using a simple, rapid and sensitive approach is still challenging. Herein, we construct a new type of biosensor for the detection of alpha S, combining the stimuli-responsiveness of liquid crystals (LCs) and the specific interaction of a DNA aptamer with proteins. In principle, the positively charged surfactant hexadecyltrimethylammonium bromide (CTAB) binds with the negatively charged DNA aptamer via electrostatic interactions; in the presence of alpha S, the DNA aptamer specifically binds with alpha S and releases CTAB, which is an amphiphilic molecule and subsequently assembles at the LC-aqueous interface, resulting in a homeotropic alignment of LCs with a dark optical signal. In the absence of alpha S, CTAB binds with the DNA aptamer without affecting the alignment of LCs, which shows planar anchoring with a bright optical signal. The response time of LCs towards alpha S is rapid and can be down to minutes. The LC biosensor established here has a good specificity for alpha S and can recognize alpha S even from a mixture of proteins. The LC biosensor also exhibits high sensitivity with a limit of detection of alpha S as low as 10 pM, which is comparable to that of the enzyme-linked immunosorbent assay. This work provides a new strategy for the detection of alpha S in a simple, rapid and sensitive manner, possessing promising potentials towards early diagnosis and clinical applications.

Automated summary

A new biosensor for detecting alpha-synuclein has been developed, utilizing the responsiveness of liquid crystals and specific interactions between a DNA aptamer and proteins. This biosensor shows rapid response time and high sensitivity, providing a promising approach for the simple and sensitive detection of alpha-synuclein.