Label free,highly sensitive and selective recognition of small molecule using gold surface confined aptamers

A highly sensitive and selective small molecule detection platform has been developed using aptamers immobilized on electrode surface. In our system, two aptamers were used – one of which is for ATP recognition and the other is for signal produce. We designed two probes L1 (containing ATP aptamer and a part of hemin aptamer) and L2 (containing the complementary strand of ATP aptamer and the rest of hemin aptamer) and immobilized L1 on electrode surface. L2 was used to hybridize to L1 and form L1–L2 duplex which brought the two parts of hemin aptamer into close proximity. Then hemin can be captured by this duplex and detected by electrochemical methods. When we introduced ATP into the system, the ATP binding destroyed the duplex and L2 diffused into the solution. As a result, hemin cannot be captured to bring electrochemical signal.