Synthesis of deep eutectic solvent-based molecularly imprinted polymer for selective extraction of emtricitabine in aqueous solutions

Abstract

The occurrence of antiretroviral (ARV) drugs in aquatic environments raises great concern due to its potential human health risks and drug resistance. The main aim of this study was to synthesize deep eutectic solvent-based molecularly imprinted polymer (DES-MIP) and apply it for the selective extraction of emtricitabine in contaminated water. The synthesis process was via bulk polymerization reaction using DES as an environmentally friendly functional monomer. Batch adsorption experiments were performed to optimize adsorption parameters such as sample pH, contact time, polymer mass and concentration of analyte in the solution. Emtricitabine was analysed using high-performance liquid chromatography equipped with a diode array detector (HPLC-DAD). The Fourier transform infrared (FT-IR) results showed the presence of the fundamental functional groups in the DES-MIP which proves the successful synthesis of DES-MIP using the prepared DES. Scanning electron microscopy (SEM) analysis revealed that the DES-MIP had a porous and rough surface compared to its corresponding nonimprinted polymer (DES-NIP) which had a smooth surface. Thermogravimetric analysis (TGA) revealed that both the DES-MIP and DES-NIP had a good thermal stability with the main thermal decomposition rate occurring at 343 ℃. X-ray diffraction (XRD) analysis confirmed that the DES-MIP was amorphous and the DES-MIP had a maximum adsorption capacity of 4,649 mg/g. DES-MIP exhibited high selectivity for emtricitabine in the presence of competing compounds with extraction. Another MIP was also synthesized using 2-vinylpyridine and its performance was compared with DES-MIP. The SEM analysis showed that there was no difference in morphology between the MIP and NIP. The MIP and NIP were thermally stable and started to decompose at 260 ℃. The extraction efficiency of this adsorbent was above 80% with a distribution coefficient of 1.62. The application of MIP in environmental spiked water samples revealed that the adsorption capacities for the river water, influent and effluent were 4.75, 4.65, and 4.71 mg/g, respectively. The extraction efficiency of emtricitabine was above 80% compared to competing competitors which had extraction efficiencies below 60%. The MIP could be reused for 5 times without losing its effectiveness. Both the DES-MIP and MIP were effective in adsorbing emtricitabine from aquatic environments. However, the MIP synthesised using 2-vinylpyridine had better extraction performance and had more affinity for emtricitabine compared to the DES-MIP. In conclusion, both DES-MIP and MIP exhibited excellent extraction efficiencies, thus demonstrating their promising potential to effectively and efficiently adsorb emtricitabine in contaminated water.