Novel dual-template molecular imprinted electrochemical sensor for simultaneous detection of CA and TPH based on peanut twin-like NiFe2O4/CoFe2O4/NCDs nanospheres: Fabrication, application and DFT theoretical study

Hollow peanut-shaped NiFe2O4/CoFe2O4 twinned nano-spherical shell composite materials have interconnected electron channels and excellent electrochemical performance, which prompted the use of this unique spatial structure to fabricate efficient electrochemical sensors. In this work, N-doped carbon dots (NCDs) incorporated into magnetic NiFe2O4/CoFe2O4 nanoparticle shell (NiFe2O4/CoFe2O4/NCDs) modified glassy carbon electrode (GCE) was applied to construct a dual-template molecularly imprinted polymer (MIP) based electrochemistry sensor (NiFe2O4/CoFe2O4/NCDs/MIP/GCE) for the simultaneous detection of catechin (CA) and theophylline (TPH). MIP was fabricated by an in-situ electrochemical polymerization strategy based on the theoretical exploration and density functional theory (DFT) computer directional simulation to screen out the optimal functional monomer (L-arginine) and the optimal ratio between the dual template molecules (CA and TPH) and functional monomer. The materials were characterized by SEM, TEM, XRD, XPS, and TGA. Besides, electron binding energy, binding constant, and imprinting factor were investigated. With the optimal conditions, the proposed electrochemical dual detection system showed outstanding analytical performance for the simultaneous sensing of CA and TPH, with an ultralow detection limit (LOD, S/N = 3) of 1.3 nM for CA in 0.01–1 μM (R2 = 0.9956) and 1–50 μM (R2 = 0.9928), as well as a LOD of 20.0 nM for TPH in the linear range of 0.1–100 μM (R2 = 0.9939), respectively. Also, the selectivity and anti-interference performances of the fabricated sensor were performed by differential pulse voltammetry and chronoamperometry, and successfully detected the analyte from tea drinks and human urine samples with the recovery rates ranging from 98.22% to 104.76% and relative standard deviations (RSD) were 1.19%–3.81%, demonstrated the sensor has excellent stability, repeatability, and reproducibility, which paves the way for other platforms to use this nanomaterial for the detection of antioxidant in the filed food safety.