NiCo

A bimetallic NiCo-based metal-organic framework (NiCo-MOF) was pyrolyzed into a novel composite comprising NiCo2O4 spinel, CoO, and metallic Co/Ni nanoparticles embedded with carbon nanotubes at high temperature 700 °C under N2 atmosphere (represented by NiCo2O4/CoO@CNTs), whereas organic ligands were almost decomposed in H2 atmosphere, leading to absence of carbon nanotubes (denoted by NiCo2O4/CoO). The feasibility of using the composite as efficient bioplatform for immobilizing the probe DNA of human immune deficiency virus-1 (HIV-1) in the electrochemical detection of the HIV-1 DNA was explored. Compared with the pristine NiCo-MOF and NiCo2O4/CoO, the NiCo2O4/CoO@CNTs composite exhibited high electrochemical activity, good biocompatibility, and strong bioaffinity toward the probe DNA. Electrochemical measurements demonstrated that the NiCo2O4/CoO@CNTs-based bioassay displayed superior sensing performances, giving an ultralow detection limit of 16.7 fM toward HIV-1 DNA over the linear range of 0.1 pM to 20 nM; possessing high selectivity even against noncomplementary and two-base mismatch sequences; exhibiting good stability, reproducibility, repeatability and applicability in the application of detecting human serum samples. Thus, the present strategy can broaden the application of MOFs and their derivatives in various fields of biosensing.