Summary
The thesis consists of three chapters:
Chapter one presents a comprehensive introduction and overview of the literature concerning nanoscience and nanotechnology. The varieties of carbon nanoparticles, according to their structures and applications, are explained along with a description of carbon-based nanomaterials. The several forms of nanozymes are presented in order of their chemical composition and catalytic activity. An overview of the usage of levodopa in the treatment of Parkinson’s disease is given along with a short explanation of pharmaceutical analysis and medication quality control. Finally, a review and description of some few previously published publications on levodopa determination are provided.
Chapter two involves the preparation procedure of Fe, N, and S co-doped carbon dots (Fe-CDs) nanozyme utilizing FeCl3 and sunset yellow as precursors using a simple single-pot hydrothermal technique. This chapter also includes the characterization of the as-prepared Fe-CDs, employing techniques like HRTEM, XRD, EDX, FTIR, fluorimetric, and UV-vis spectrophotometry. The Fe-CDs exhibit intense green fluorescence at 443 nm with excitation-independent properties and a high fluorescence quantum yield of 40.23 %. The catalytic activity of the nanozyme was investigated by catalyzing the oxidation reaction of tetramethylbenzidine (TMB) in the presence of hydrogen peroxide to yield a blue-colored TMBox at 652 nm. The steady-state kinetic assay of Fe-CDs was also conducted to find the Michaelis-Menten constant (Km) and maximum reaction velocity (Vmax) using the Michaelis-Menten equation and Lineweaver- Burk plot. Finally, the AGREE tool and RGB model were applied to evaluate the greenness and whiteness of the proposed method.
In chapter three, the analytical application of the Fe-CDs is presented. Dual detection methods were established to determine levodopa (L-dopa) with the advantage of the high nanozyme activity and the distinct fluorescent aspect. Both determination methods are depended on the L-dopa oxidation by hydrogen peroxide in the presence of Fe-CDs and the vanishing of the TMBox blue color. The colorimetric method monitors the amount of fading color of the TMBox at 652 nm. While in the fluorometric method, the formed blue TMBox absorbs the emission light of the Fe-CDs; when L-dopa is present, this effect decreases, and the intensity of the emission light increases. The colorimetric and fluorometric nanozyme-based detection procedures show good linearity and validity without the effect of interferences. The colorimetric and fluorescent nanozyme-based detection procedures show good linearity (2.17×10-3 to 34.78×10-3 mM) and (0.85×10-3 to 16.95×10-3 mM) and limit of detection of (0.84×10-3 mM) and (0.102×10-3 mM) for both colorimetric and fluorometric methods respectively without the effect of interferences. The remarkable consensus between the results obtained from the analysis of real samples (pharmaceutical and blood) and those acquired from HPLC demonstrates the high applicability of the presented methods.