Microcantilever Sensor In The Application For Biomolecular Recognition And Detection

Microcantilever sensing technology is a new analysis method and developedbased on the Micro Electro Mechanical Systems and Atomic Force Microscopy. Inrecent years, since it has the advantages of high sensitivity, fast response, label-freeand in real-time monitoring, these characters make the microcantilever sensorappealing for applications in the biological molecular recognition and detection in thefuture. Its detection principle is as following: when the biochemical reactions occur onthe microcantilever unilateral surface, the surface stress will change, which makes themicrocantilever bend. Then we can obtain the information of the biochemicalreactions by detecting the microcantilever deflection with optical lever methods. Inthis paper, the main contents, method, results and conclusions as follows:1. We developed an aptamer based microcantilever sensor for detection ofadenosine triphosphate (ATP). First, The thiol-capped aptamer was functionalizationto the gold surface of the microcantilever via Au-S bond, and then the interactionbetween aptamer and ATP on the gold surface changed the surface stress, resulting thecantilever to bend. The results demonstrated that the cantilever deflections increasedwith the increase of ATP concentrations and a good linear correlation between thedeflection and concentrations of ATP in the range of0.5～5mmol/L with acorrelation coefficient of0.998. The detection limit was0.06mmol/L. In this work,we injected the ATP analogue, such as CTP, GTP and UTP, the cantilevers have nosignificant deflection. This indicated that our proposed microcantilever sensor hasgood selectivity, simple and label-free for ATP.2. We successfully developed an aptamer based microcantilever sensor forlabel-free detection of nucleolin in the running buffer. The results demonstrated thatthe cantilever deflections increased with the increase of the nucleolin concentration and illustrated a good linear correlation between cantilevers deflection andconcentrations of nucleolin in the range of10～250nmol/L with a correlationcoefficient of0.999. Additionally, the detection limit is calculated to be about1nmol/L. It indicated that the microcantilever sensor has high sensitivity for nucleolinand potassium ion ions concentration in the running buffer are essential for theinteraction between AS1411and nucleolin. In the same experiment condition, weintroduced s thrombin, lysozyme and bovine serum albumin (BSA), no significantdeflection of the cantilevers was observed. It indicates that the designedaptamer-based microcantilever sensor has high selectivity to nucleolin.3. The trans-zeatin aptamer was functionalization to the gold surface of themicrocantilever via Au-S bond. Then we study the interaction between aptamer andtrans-zeatin in the running buffer. Compared to traditional technology, microcantileversensor is a label-free detection method and it can to monitoring the interactionbetween aptamer and trans-zeatin in real-time. We also used the electrochemicalsensor to detection the trans-zeatin. The results demonstrated that with the increase oftrans-zeatin concentration, the peak current of DPV was decreased and the peakcurrent of DPV and trans-zeatin concentration logarithm has linear correlation inrange from100～6000nmol/L with a correlation coefficient of0.973. Additionally,we investigate the selectivity of aptamer-based electrochemical sensor for trans-zeatin,it illustrated that this sensor has good selectivity for trans-zeatin.