TCNQ-doped Cu-metal organic framework as a novel conductometric immunosensing platform for the quantification of prostate cancer antigen

Abstract

Due to their hierarchical structures and high surface areas, several categories of metal organic frameworks (MOFs) have emerged as next-generation materials for a wide variety of applications, including sensors. However, the poor electrical conductivity is a bottleneck to exploit them in the development of electrochemical sensing devices. In this work, we for the first time report the development and application of tetracyanoquinodimethane (TCNQ)-doped thin films of copper-MOF, Cu-3(BTC)(2), assembled on gold screen printed electrodes, as an electrochemical sensing platform for highly sensitive detection of a prostate cancer marker. The structural and spectroscopic features of the synthesized material along with the morphological features of the prepared electrodes were characterized with diverse instrumental techniques. Doping the thin films of Cu-3(BTC)(2) with TCNQ improved the conductance of the base material by nine orders of magnitude (from 10(-12) to 10(-3) S). This conducting platform was modified with antibodies to design an immunosensor for the prostate cancer antigen (PSA). The anti-PSA conjugated TCNQ-Cu-3(BTC)(2) provided PSA detection in a dynamic linear range of 0.1-100 ng/mL to attain a limit of detection at 0.06 ng/mL. The above sensor was specific to PSA even in the presence of other proteins. The practical utility of the immunosensor was also demonstrated against some spiked serum samples. The herein proposed TCNQ-Cu-3(BTC)(2) based detection system involves a robust physical immobilization of the antibodies to facilitate the detection of PSA over a broader and clinically significant concentration range.