Biosensors based on Atomic force microscope (AFM) cantilevers have recently been showing promising potential because of its portability and high sensitivity, the gold coated cantilever surface allows functionalization on the cantilever by immobilizing biomolecules like enzyme, DNA, RNA on the cantilever surface. Biomolecular reactions between the immobilized molecules and its target molecules on the cantilever can result in change in measurable mechanical signal like deflection, resonant frequency. Researchers can detect the presence and quantity of target molecules by measuring the deflections or resonant frequency change. This property of micro cantilever allows itself to have potential application in DNA/Protein detection. In addition, the gold surface of cantilever makes it possible to apply electrochemical technology in the biosensing system.
We designed a mini optical system to monitor the deflection of cantilever when the DNA aptamer of Ebola virus glycoprotein (GP1,2) that is immobilized on the cantilever reacts with GP1,2 in the environment. The same experiment was conducted using Ebola secreted glycoprotein (sGP) and its DNA aptamer. The results show that the increase of GP1,2 concentration led to an increase in tensile surface stress, the tensile surface stress saturated at about 200nM of GP1,2. While the sGP results show that the increase of sGP concentration produced a compressive surface stress which saturates at 20nM. The linear range of experiment data has potential in the detection of Ebola virus at nanomolar concentration.
We also set up a micro optical system of shoe box size to monitor the deflection of cantilever when the immobilized aptamers bind with target molecules in the environment. A verification with human alpha thrombin and its aptamer was conducted, which shows a promising potential of alpha thrombin detection. The portability of this new system allows a rapid detection at point-of-care.
Other future work is planned in the last chapter, which includes a molecular dynamics simulation of stress induced by the binding between glycoprotein and its aptamer, and a novel electrochemical biosensor based on micro-cantilever
