Abstract
Molecular logic gates, which have attracted increasing research interest and are crucial for the development of molecular-scale computers, simplify the results of measurements and detections, leaving the diagnosis of disease either “yes” or “no”. Prion diseases are a group of fatal neurodegenerative disorders that happen in human and animals. The main problem with a diagnosis of prion diseases is how to sensitively and selectively discriminate and detection of the minute amount of PrPRes in biological samples. Our previous work had demonstrated that dual-aptamer strategy could achieve highly sensitive and selective discrimination and detection of prion protein (cellular prion protein, PrPC, and the diseases associated isoform, PrPRes) in serum and brain. Inspired by the advantages of molecular logic gate, we further conceived a new concept for dual-aptamer logic gate that responds to two chemical input signals (PrPC or PrPRes and Gdn-HCl) and generates a change in fluorescence intensity as the output signal. It was found that PrPRes performs the “OR” logic operation while PrPC performs “XOR” logic operation when they get through the gate consisted of aptamer modified reusable magnetic microparticles (MMPs-Apt1) and quantum dots (QDs-Apt2). The dual-aptamer logic gate simplifies the discrimination results of PrPRes, leaving the detection of PrPRes either “yes” or “no”. The development of OR logic gate based on dual-aptamer strategy and two chemical input signals (PrPRes and Gdn-HCl) is an important step toward the design of prion diseases diagnosis and therapy systems.
Highlights
Logic gate, an original concept of a programmable computer, performs a logical operation on one or more logic inputs and produces a single logic output
The Principle of Dual Aptamer Strategy Our strategy starts with the chemical modification of MMPs and quantum dots (QDs) with Apt1 and Apt2, respectively (Figure 1)
It can be seen that the fluorescence intensities got increased dramatically either PrPC or PrPRes was incubated with MMPs-Apt1 and QDsApt2 (Figure 2a), suggesting that the two aptamers are both able to bind with PrP simultaneously and the cocktails of MMPs-Apt1PrP-Apt2-QDs formed
Summary
An original concept of a programmable computer, performs a logical operation on one or more logic inputs and produces a single logic output. Molecular logic gates, which have attracted increasing research interest, perform logical operation inputs resulting from chemical or biological processes and generate a single logic output such as spectral or electrochemical signal. As the pathological form of prion protein, PrPRes, is abundant only at the late stages in brain, the main problem for prion diseases diagnosis at pre-symptomatic stage is how to detect the minute quantities of PrPRes in complex biological systems. Methods such as western blot assays and enzyme-linked immunosorbent assays (ELISAs) are insuficient sensitive. Researchers attempted to use conformational antibodies with various spectroscopic techniques to improve the sensitivity [10,11,12,13], the worldwide application of such methods is limited by the usefulness and specificity of antibodies or expensive and sophisticated equipment
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