Near-infrared photoelectrochemical and colorimetric dual-mode aptasensor for determining osteopontin based on Er-MOF nanoballs@gold nanoparticles and Au2Pt nanozymes

A near infrared photoelectrochemical (PEC) and colorimetric dual-mode aptasensor was fabricated for efficiently determining osteopontin (OPN). Er-MOFs and Au2Pt nanoparticles were successfully synthesized. The gold nanoparticles (AuNPs) modified Er-MOF (Er-MOFs@AuNPs) nanocomposites were introduced into the glassy carbon electrode (GCE) to construct a photoelectrochemical sensing interface. OPN aptamer (Apt1) was immobilized onto the Er-MOFs@AuNPs based photoelectrochemical platform through Au-S bond for the selectively recognizing osteopontin. Au2Pt-labeled OPN aptamer (Au2Pt-Apt2) was subsequently captured onto the OPN/Apt1/MOFs@AuNPs/GCE surface to form a sandwich sensing interface, leading to an enhancement on the photocurrent response. Interestingly, Au2Pt nanozyme which possesses peroxidase activity could produce a solution color change in the presence of 3,3 ',5,5 '-tetramethylbenzidine (TMB) and hydrogen peroxide. The variations of photocurrent response and absorbance can be employed for the quantitative detection of OPN. Under the optimal conditions, the PEC and colorimetric sensing strategies show linear responses towards OPN in the concentration range of 0.01 - 25 ng mL-1 and 1 - 850 ng mL-1, respectively. The calculated determination limits were 2.6 pg mL-1 and 0.04 ng mL-1. The PEC and colorimetric dual-mode sensing platform can provide no crosstalk results and can be mutually verified, thus effectively improving the accuracy and reliability for the determination of OPN.