Muhammad Mujeeb AshrafCIIT/FA23-RPH-027/LHRDr. Kashif TufailLHR TP 100012026-03-052025https://repository.cuilahore.edu.pk/handle/123456789/2650A novel cerium-cobalt metal-organic framework (Ce/Co-PTC-MOF) was designed and employed as a fluorescence quenching sensor for the fast and selective detection of Ochtratoxin A(OTA) in food sample based on Ce redox properties and dual oxidation state. The Ce/Co-PTC-MOF was characterized using X-ray diffraction (XRD), Raman spectroscopy, Fourier-transform infrared spectroscopy (FTIR), photoluminescence (PL) spectroscopy, zeta potential measurements, and field emission scanning electron microscopy (FE-SEM) were employed for characterization. The MOF exhibited a hierarchical microstructure with a 3D flower-like morphology composed of ultrathin, interwoven nanosheets with strong negative surface charge. The fluorescence quenching response of Ce/Co-PTC-MOF was optimized by investigating the effects of MOF concentration, sonication time, incubation time, and pH on the quenching efficiency of Rhodamine B (Rh-B). The sensing mechanism was validated through fluorescence emission spectra, demonstrating efficient quenching of Rh-B by Ce/Co- PTC-MOF and significant fluorescence recovery upon the introduction of OTA. A machine learning (ML) approach was employed to enhance the sensor’s analytical capability by modeling the non-linear relationship between fluorescence recovery and OTA concentrations. The sensor exhibited a strong linear response to OTA concentrations ranging from 0.2 to 250 ng/L, with a low limit of detection of 10 pg/ml Electrochemical mode with electroactive surface area increased by nearly twice and electron-transfer kinetics increased at a moderately higher rate as compared to unmodified GCE, Ce/Co-PTC-MOF-modified glassy carbon electrodes (GCEs) generated electrochemical mode products. Surface blocking/passivation controlled the detection mechanism as OTA adsorption at Ce/Co site selectively reduced the difference pulse voltammetry (DPV) peak currents and augmented charge-transfer resistance (Rct) in electrochemical impedance statistica (EIS). The sensor worked on the principle of DPV with the sensitivity of 193.8 mAng-1mL +cm +2 and the detection limit was found as 0.1775 ng/mL, whereas the EIS gave a even lower result with a LOD of 0.20 ng/mL. The selectivity investigations showed the high specificity to the OTA as compared to other mycotoxins and in spiked food sample the maximum recoveries were 99.12 to 102.05 with a low relative standard deviation. According to the obtained results, the Ce/Co-PTC-MOF represents a high-potential multifunctional platform to detect OTA in food safely and without quality concerns with high sensitivity and selectivity as well as practicably, suitable in foods quality controlenDepartment of PhysicsFA23PhysicsFoodborne Mycotoxin DetectionElectrochemical dual mode SensorMetal Organic Frame WorkDr. Kashif TufailThesis