Electrochemical Method Based On Molecularly Imprinted Polymers For Drug Detection

The research discusses the development of innovative electrochemical sensors using molecularly imprinted polymer nanoparticles (nano-MIPs) for the detection of Amphetamine, Diclofenac, and Fentanyl. These nano-MIPs, often called "plastic antibodies" or "synthetic receptors", are promising materials for the development of selective, affordable, rapid, and durable sensors due to their molecular recognition capabilities.

In chapter two, an electrochemical sensor for Amphetamine was created using different silanes (APTES and AHAMTES) to prepare nano-MIPs. The produced nano-MIPs were characterised using dynamic light scattering (DLS) and a transmission electron microscope (TEM). Their performance within the range 75 nM up to 220 nM in a phosphate-buffered saline (PBS) showed sensitivities of 0.2745 μA-1 nM and 0.290 μA-1 nM, with limits of detection (LODs) of 0.11 nM and 0.10 nM respectively. In human plasma, these values shifted slightly, but both showed high selectivity, and reproducibility towards Amphetamine.

The third chapter enhanced the Amphetamine sensor's performance by incorporating fabricated graphene oxide ink into the screen-printed platinum electrode. The Amphetamine sensor's performance further improved, achieving a sensitivity of 0.452 μA-1 in PBS and 0.4041 μA-1 nM in human plasma, with even lower LODs.

The fourth chapter, the first sub chapter focused on the detection of Diclofenac using nano-MIPs synthesized through a solid-phase synthesis approach. The nano-MIPs were characterised and used in the developed and fabricated sensor for the detection of diclofenac in the model solution and spiked biological samples using DPV. DLS, TEM, and SEM were used to characterize the nano-MIPs. The responses of the diclofenac nano-MIP sensor in the PBS were in the range of 50 μM–800 μM with a sensitivity number of 0.055 μM; the LOD was 2.42 μM. Whereas, the fabricated using graphene ink, in PBS, the sensor's sensitivity was 0.046 μM with an LOD of 4.11 μM. When the sensor was applied to a biological context, it demonstrated a sensitivity of 0.072 μM and an LOD of approximately 4.18 μM, highlighting its potential for medical applications.Lastly, in the second sub chapter a sensor was developed for fentanyl using nano-MIPs. In PBS, whiten the range of 5 nM and 60 nM showed a sensitivity of 0.445 μA μM-1, an LOD of 0.28 nM, and a limit of quantification (LOQ) of 0.85 nM. When applied to human plasma, its sensitivity was 0.4077 μA μM-1, with LOD and LOQ values of 1.65 nM and 5 nM, respectively.

Overall, the study demonstrates the potential of nano-MIPs as "plastic antibodies" for the development of selective, cost-effective, rapid, and stable electrochemical sensors for detecting these specific substances.