Team:BIT/BA1
Abstract
Cancer is one of the three major killers that threatened mankind since the 21st century. The reason is that it is not taken seriously at the beginning of cancer until it is detected in the middle and late stages, resulting in a very low cure rate. Therefore, early detection becomes a decisive factor to improve the cure rate of cancer. In this project, we use alpha-fetoprotein (AFP)as an example, using the factor that AFP can specifically bind to the aptamer, to achieve a signal conversion that using a small molecule (lysine) to replace AFP content in serum, just like equivalent substitutions in mathematics, to achieve the early detection of liver cancer. This system can be extended to all of the disease detection, which use protein as biomarkers.
Introduction
After the lysine has been dissociated from complementary chain, it will induce the growth of E.coli ΔLysA, which can hardly grow without the addition of lysine. Thus we have transformed our own-designed circuit to the E.coli ΔLysA, which can express fluorescent protein as it grows. In this way, we can transform the concentration of lysine to the fluorescent intensity which can be detected through the machine.
But the concentration of the lysine is very low, resulting in a low fluorescent intensity. To solve this problem, we designed a strong promoter, cyclic amplifier system and a dual fluorescence system in our genetic circuit to ensure a much higher signal strength and sensitivity, which is definitely beneficial to our detection of AFP.
The conventional methodAs shown, pcat is a strong constitutive promoter, which can promote the induced promoter plux. Promoter plux can be induced by the compound of LuxR and AHL. Downstream the plux, we designed the a cyclic amplifier system: luxR generator codes LuxR, and LuxI generator codes luxI, which can catalyze the synthesis of AHL. When the concentration of AHL has reached the threshold value, AHL combines LuxR to form a compound, strongly inducing the promoter plux. This induction will continue to induce the expression of the luxR and luxI generator downstream, forming a positive feedback. That’s how our cyclic amplifier works. is ELISA and other antibody-based techniques to enrich low-abundance molecular markers. ELISA which is based on "antigen-antibody reaction" of the detection method is a little bit expensive. Time and temperature are having a greater impact for its detection.
The purpose of this project is to establish a detection platform suitable for most molecular markers. The platform is low cost, simple to operate and has strong anti - interference ability.
