A new sensor for detecting microrna 133B (Parkinson’s disease biomarker)

The discovery of small non-protein coding regulatory RNAs, such as short microRNAs (miRs) has enabled the detection of diseases, e.g. Alzheimer's disease and breast cancer. The diagnoses of such diseases were previously difficult due to reasons of specificity of the technique and low concentrations of the targets. To this end, miR associated with diseases such as Parkinson's disease have started to be pursued as analytical biomarkers using electrochemical sensors. Such sensors can provide high sensitivity, low detection limits and rapid analysis times. These powerful advantages are an effective means to mitigate the problems associated with low miR concentrations and short lifespans. In this work, we report the development of a new signal-on biosensor for selective and ultrasensitive detection of miR 133b, a known biomarker for Parkinson's disease. The sensor utilizes complementary ss-DNA sequence labelled with methylene blue redox marker attached to a gold electrode surface to generate current response for miR 133b when subjected to cyclic voltammetric measurements. The continuous cycling between the oxidation and reduction of methylene blue in presence of tris(2-carboxyethyl) phosphine hydrochloride, as a strong reductant, was used to amplify the response. Under optimum conditions, the sensors achieved a linear concentration range of 10 fM to 520 pM, a detection limit of 168 aM, and a sensitivity of 0.3 nA pM−1. Furthermore, the sensors successfully distinguished between matched and mismatched sequences of miR, suggesting promising potential for eventual applications in vitro.