Direct electrochemistry of silver nanoparticles-decorated metal-organic frameworks for telomerase activity sensing via allosteric activation of an aptamer hairpin

A direct electrochemistry of silver nanoparticles (AgNPs)-anchored metal-organic frameworks (MOFs) is developed for detection of telomerase activity based on allosteric activation of an aptamer hairpin. AgNPs in situ decorated on PCN-224 (AgNPs/PCN-224) constituted the direct electrochemical labels that were further biofunctionalized by recognition moiety of streptavidin (SA). To achieve the target biosensing, an allosteric hairpin-structured DNA was elaborately designed for signal transduction. The presence of telomerase elongated its primer in the hairpin to displace partial stem strand, thus resulted in the formation of SA aptamer-open structure. Through the specific interaction with aptamer, SA-biofunctionalized AgNPs/PCN-224 probe was attached onto the electrode surface, generating electrochemical signal at + 0.072 V of AgNPs centralized by MOF structure. The direct electrochemical biosensor showed target activity-dependent response from 1.0 × 10⁻⁷ to 1.0 × 10⁻¹ IU L⁻¹ with a detection limit of 5.4 × 10⁻⁸ IU L⁻¹. Moreover, the sensor was applied in evaluation of telomerase activity in living cancer cells. The established electrochemical detection approach in this work avoids the critical deoxygenation conditions and additional electrocatalytic reagents, which opens a novel biosensing perspective for direct electrochemistry of MOF-based nanocomposites.