µROX - µRNA Redox cycling

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This project aims to develop a rapid, low-cost and ultrasensitive electrochemical lab-on-a-chip (LOC) platform comprising multiplexed microfluidics for the simultaneous detection of different microRNAs (µRNAs) without any sample treatment. µRNAs, small non-coding RNA molecules, play a potential role as diagnostic and prognostic biomarkers. Nowadays there are many different diagnostic platforms for the µRNA profiling in centralized laboratories. However, due to their bulky and expensive equipment, and their need for a sample treatment along with a high sample volume they are not suitable for an application in point-of-care testing (POCT). To cover the demand for portable and fast point-of-care devices it is of great importance to realize a LOC platform allowing the measurement of multiple µRNAs with fast sample-to-result times (e.g. without any sample preparation) along with a low sample consumption (e.g. blood from a finger prick). Microfluidic LOC platforms offer an acceleration of the specific and sensitive detection of various biomarkers. The proposed electrochemical µRNA sensor is based on the combination of different amplification techniques. To increase the device sensitivity, interdigitated electrode arrays with gap sizes in the nanometer range are employed. In this regard, the technological limits will be investigated to achieve the possible highest amplification. In order to obtain enzyme-mediated signal amplification, the stop-flow technique is utilized. A further signal amplification is achieved by DNA or RNA strains and/or by an appropriate surface modification to increase the number of binding sites. The combination of these amplification approaches represents a drastic increase in sensitivity compared to the conventional electrochemical methods and allows a fast and reliable measurement of µRNAs without prior amplification by means of polymerase chain reaction (PCR) techniques. One of the specific applications for µRNAs, where only a low sample volume is available, is the aggressive brain tumor in young children (earliest incidence 18 month), known as Medulloblastoma (MB). Beside the histopathologic classification of MB, it can be divided into four molecular subtypes. An early classification of these subtypes or detection of relapse will increase the survival chances of patients. This proposal is dedicated to implement a new detection method for cancer research using a unique interplay of different research fields (Micro-Nanotechnology, microfluidics and biomedicine). A successful demonstration of the multiplexed µRNA profiling system will have a great impact on clinical diagnostics, especially in POCT, and will be a low-cost and user-friendly alternative to standard PCR systems and other diagnostics systems. Furthermore, it will be possible to measure µRNAs not only in samples like blood plasma, saliva and urine, but also directly in undiluted serum or even whole blood.