Development of various nanocomposite-based molecular printed sensors for zearalenone detection and application to rice samples

Zearalenone (ZEA) is a mycotoxin that has a carcinogenic efect and is often found at a high rate in frequently consumed foods. In this study, three different methods are presented for the detection of ZEA in foods. The first of these methods, a characteristic molecular imprinted quartz crystal microbalance (QCM) sensor based on molybdenum disulfde nanoparticle (MoS2NPs)-multiwalled carbon nanotube (MWCNT) nanocomposite (MoS2NPs-MWCNTs) is presented for selective determination of ZEA in rice samples. Firstly, molybdenum disulfde nanoparticle (MoS2NP)-multiwalled carbon nanotube nanocomposites were characterized by using microscopic, spectroscopic, and electrochemical techniques. Then, ZEA-imprinted QCM chip was prepared in the presence of methacryloylamidoglutamicacid (MAGA) as monomer, N,N′-azobisisobutyronitrile (AIBN) as initiator, and ZEA as target molecule by using UV polymerization. The sensor revealed a linearity toward ZEA in the range 1.0–10.0 ng L−1 with a detection limit (LOD) of 0.30 ng L−1. The high repeatability, reusability, selectivity, and stability of the developed sensor enable reliable ZEA detection in rice samples. As the second method, a zearalenone detection based on molecularly imprinted surface plasmon resonance (SPR) sensor including sulfur-doped g-C3N4/Bi2S3 (S-g-C3N4/Bi2S3) nanocomposite was presented for selective determination of ZEA in rice grain samples. After S-g-C3N4/Bi2S3 nanocomposite was synthesized by calcination method with high purity and in accordance with green chemistry, ZEA imprinted SPR chip based on S-g-C3N4/Bi2S3 was prepared in presence of MAGA as monomer, ethylene glycol dimethacrylate (EGDMA) as cross linker, AIBN as initiator and ZEA as target molecule by using UV polymerization. Then, the spectroscopic, microscopic and electrochemical methods were used for the characterizations of the nanocomposite and the proposed ZEA imprinted SPR chip based on S-gC3N4/Bi2S3. The SPR sensor showed a linearity towards ZEA in range of 1.0 – 10.0 ng/L with a LOD of 0.33 ng/L. Thus, the developed sensor's high repeatability, stability, reproducibility and selectivity provided reliable ZEA determination in rice grain samples, ensuring safe food consumption. As the last method, a novel electrochemical sensor based on graphitic carbon nitride nanosheets decorated bovine serum albumin@MnO2 (gC3N4NS/BSA@MnO2) nanocomposite and molecularly imprinted polymers (MIPs) was developed and applied to rice samples for ZEA determination. Firstly, the synthesis of bulk g-C3N4 by thermal poly-condensation method was completed. After the ultra-sonication treatment of bulk g-C3N4 providing graphitic carbon nitride nanosheets, the nanocomposite was successfully produced via electrostatic forces between g-C3N4NS and BSA@MnO2. Then, a novel MIP-based electrochemical electrode including g-C3N4NS/BSA@MnO2 was prepared in the presence of ZEA as target analyte and pyrrole (Py) monomer by cyclic voltammetry (CV). The formed electrochemical sensor exhibited a linearity of 1.0 – 10.0 ng L− 1 with a LOD of 0.25 ng L− 1. Furthermore, the high selectivity, reproducibility and stability of the prepared MIPebased electrochemical sensor exhibited that it could be used in real sample analysis such as rice.