الفهرس 
General IntroductionOnly 14 pages are availabe for public view
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Abstract
This thesis discusses the utilization of molecularly imprinted polymers (MIPs) in three main analytical applications including, molecular imprinted solid phase extraction (MISPE), enantioseparation, and optical sensors. It is composed of the following parts: Part I: General Introduction to Molecular Imprinted Polymers. This part includes two chapters: Chapter 1: Road Map for Synthesis of Molecular Imprinted Polymers. This chapter summarized the main steps during MIP preparation, different methods of characterization, and assessment of imprinting efficiency. MIP preparation starts with the selection of suitable monomers based on the nature of the used template. The template tends to form a stable complex with the used monomers. According to the type of bond formed between template and monomer molecules, three imprinting approaches are reported: covalent, non-covalent, and semi covalent. Then, polymerization of that complex takes place to produce MIP with template occupied binding sites or imprint cavities. So, for the completion of imprinting process and hence vacant cavity production, a suitable effective extraction technique is used. The assessment of template extraction process can be either direct, by template detection in the washing solution, or indirect, by measuring certain physical property of the polymer before and after template removal. In addition, this chapter discussed the most common methods of MIPs characterization including chemical, morphological, and binding sites characterization. Finally, the different parameters determined to assess the imprinting efficiency were summarized. 2: Chitosan-based Molecular Imprinted Polymers. This chapter discussed the chemical and physical properties of CHT. In addition, the preparation of CHT-based sol gel MIPs was discussed. The most used physical and chemical crosslinkers were summarized, with dialdehydes discussed in detail. Part II: Chitosan-based Ketorolac Imprinted Polymer as solid phase extraction Sorbent: Application to Ketorolac Determination in Plasma. This part includes three chapters: Chapter 1: Introduction and literature review. This chapter argued solid phase extraction techniques used in sample treatment. The dispersive solid phase extraction was compared to the traditional cartridge-based technique with respect to efficiency and selectivity. The advantages of MISPE were debated as well. In addition, a review of CHT-based MIPs used for clean-up, extraction, and purification of different samples was presented. Chapter 2: Preparation and characterization of ketorolac imprinted polymer. Ketorolac imprinted polymer (KET-MIP) was prepared employing sol gel method, using CHT as monomer and glutaraldehyde (GLA) as crosslinker, in presence of ketorolac (KET). Solvent extraction, using 0.1 M HCl, was adapted for template removal. The completeness of template removal was assessed directly and indirectly by recording the UV spectra of washing solution and FTIR spectra of the KET-MIP, respectively. Nonimprinted polymer (NIP) was prepared and used as a control to address how it differs from MIP during characterization. The prepared polymer was characterized chemically and morphologically using FTIR and SEM, respectively. The surface area and pore diameter were measured using Brunauer Emmet Teller. Maximum adsorption capacity and % desorption ratio were attained at pH 5.00 for 20 min and 0.1N HCl for 30 min, respectively. Moreover, the enrichment of KET was maximized by adjusting the elution volume and resin amount. The kinetics data of KET binding to both KET-MIP and NIP were best fitted to pseudo second order kinetic model indicating chemical sorption. Adsorption isotherm investigations revealed monolayer homogenous binding indicated by the data fitting to Langmuir model and Freundlich heterogeneity index approaching unity. The efficiency of the imprinting process was indicated by imprinting factor of 1.45, specific factor less than zero for the tested interfering substrates, and % specific adsorption ratio of 31.28%. The obtained results indicated the specificity of the prepared KET-MIP. Chapter 3: Application of ketorolac imprinted polymer for solid phase extraction and spectrophotometric determination of ketorolac in spiked human plasma. In this chapter, the specificity of the prepared KET-MIP was exploited enabling the spectrophotometric determination of KET in spiked human plasma after its selective D-μSPE. A new method based on the measurement of the amplitude of the 2D357 peak of the MISPE eluate of the spiked plasma samples was developed. The proposed method was validated as per the ICH M10 guidelines in terms of linearity, selectivity, accuracy, and precision. The calibration curve was found linear over the range of 2 – 20 μg/mL and the LLOQ was found to be 2 μg/mL. The validity of the calibration set was indicated by %RSD, back calculated for the calibration standard, within ±20% of the nominal concentration at all concentration levels including the LLOQ and ULOQ. The overall within-run accuracy at each concentration level were within ±20% of the nominal values, including the LLOQ and ULOQ. The response detected and attributable to interfering components in blank samples were found to be 15.60% ± 1.84, less than 20% of the analyte response at the LLOQ, indicating method selectivity. No significant differences were observed between the results obtained by the proposed method and a reported HPLC method, revealed by both t-test and F-test. The obtained results indicated that extraordinary features of MIPs enabled the selective determination of drugs in complex matrix such as plasma using a nonselective optical device. This can be considered as a step towards high efficiency and tunable spectral selectivity. Such tailored couples will have great potential for wide applications in clinical tests, environmental monitoring, and other analytical areas. The work conducted in this part was published in Spectrochimica Acta A volume 241 (118668). Part III: Chitosan-based chiral MIP: application to ketoprofen and ketorolac enantioseparation. Chapter 1: Introduction and Literature review In this chapter, the use of MIPs as chiral stationary phases was reviewed showing their advantages. Literature review revealed that the preparation of chiral MIPs required either a single pure enantiomer template or chiral monomer to induce enantioselectivity in the formed cavity. The chiral properties of CHT were also discussed. A novel racemic imprinting process was introduced employing the chiral properties of CHT monomer. Chapter 2: Preparation and characterization of racemic ketoprofen imprinted polymer. This chapter presented a novel racemic imprinting process employing the chiral properties of CHT monomer. The preparation of CHT-based racemic ketoprofen imprinted polymer (RS-KTP/MIP) was conducted using CHT as monomer, GLA as crosslinker, and RS-KTP as a template. Solvent extraction, using 0.1 M HCl: MeOH (50:50, v/v) as washing solvent, was adapted for template removal. Direct detection of RS-KTP in washing solvent at 260 nm was used for the assessment of the template removal step. The RS-KTP adsorption onto both RS-KTP/MIP and NIP was conducted using phosphate buffer pH 5.00 for 20 min. The nature of elution solvent affected both the elution kinetics and % desorption ratio suggesting a heterogenous nature of the formed binding sites. Adsorption kinetic experiment indicated chemical sorption rather than physical entrapment. Adsorption isotherms investigations revealed monolayer adsorption indicated by Langmuir fitting. The heterogeneity of the binding sites was supported by Freundlich heterogeneity index of 0.8471. Good imprinting was indicated by an imprinting factor of 7.97 and 3.50 for RS-KTP and S-KTP, respectively. The results obtained in this chapter demonstrated the high efficiency of imprinting and template removal process. Chapter 3: Evaluation of enantioselectivity and enantioseparation ability of the racemic ketoprofen imprinted polymer. This chapter examined the enantioselectivity of the RS-KTP/MIP in both batch and dynamic experiments. S-KTP/MIP and NIP were used through all the way through the chapter as positive and negative control, respectively. The selectivity of the RS-KTP/MIP towards S-KTP was indicated by selectivity coefficient of 2.31. A SPE cartridge packed with RS-KTP/MIP enabled resolution of RS-KTP using gradient elution solvent system composed of 0.1 M HCl (100%) followed by 50% increment of methanol. Scatchard plot revealed two binding site types of different affinity and density observed for the RS-KTP/MIP compared to S-KTP/MIP. The binding capacity of RS-KTP/MIP showed observed dependence on the % enantiomeric excess (%ee) of KTP solution with greater binding capacity values obtained for solutions containing higher S-KTP percentage. These results indicated the enantioselectivity of the racemic imprinted polymer. The success of using racemic template for the preparation of enantioselective MIP brings a new possibility to achieve enantioseparation of racemic mixtures having very expensive or unavailable pure enantiomers. Chapter 4: Application of racemic imprinting to ketorolac enantioseparation. This chapter explored the applicability of the novel racemic imprinting concept to racemic resolution of KET, a candidate racemic drug whose pure enantiomers are not available. The enantioselectivity of the CHT-based racemic KET imprinted polymer (RS-KET/MIP) was evaluated using batch experiment showing an enantioselectivity coefficient of 2.65. The enantioselectivity of the tested RS-KET/MIP toward S-KET was indicated by a % ee of 59.66% of the residual solution. A SPE cartridge packed with the tested polymer was successfully used for the resolution of racemic KET employing gradient elution solvent system. The RS-KET/MIP was packed into an HPLC column to investigate its applicability as CSP. The chromatographic resolution trials revealed a mixed HILIC and RP separation modes in addition to the imprinted cavities. The nonuniform nature of the polymer particles and nonefficient column packing disabled achieving baseline separation. Part IV: Nanocomposites sensor based on CHT stabilized silver nanoparticles. This part is composed of three chapters: Chapter 1: Introduction and literature review. This chapter discussed the utilization of CHT fluorescence in optical sensors presenting some reported technique applied for its enhancement such as carbonization, micellization and derivatization. In addition, it discussed the Fluorescence Resonance Energy Transfer strategy as a common mechanism recently applied in pharmaceutical analysis. Chapter 2: CHT-based Fluorescence resonance energy transfer sensing strategy for ketorolac detection. In this chapter, a novel green eco-friendly turn-on FRET sensing strategy was developed for detection of KET. One-pot water-dispersed CHT stabilized silver nanoparticles (AgNPs) solution was synthesized by complexation of micellized chitosan (MCT) solution with silver nitrate at low temperature followed by subsequent reduction using sodium borohydride at 70°C. The preparation method was mild and produced AgNPs solution stable for eight months at 4°C. Owing to the spectral overlap of the fluorescent spectrum of CHT and absorption spectrum of AgNPs, a novel sensitive turn-on FRET sensing strategy was established based on enhancement of CHT fluorescence by electrostatic destabilization of the monodispersed AgNPs upon the addition of KET. The sensor solution was applied for the selective detection of KET from 0.05 to 0.4 μM in injection dosage forms and spiked environmental water samples with no interference either of the KET photocatalyzed degradation product or other interfering structurally related or coexisting substances. The developed strategy showed promising results and could be applied practically for the detection of KET in injection dosage forms and environmental water. The work conducted in this chapter was published in Colloids and surfaces A volume 624 (126182). Chapter 3: Application of molecular imprinting technology to the CHT stabilized silver nanoparticles sensor. This chapter investigated the applicability of MIT to the developed sensing strategy through the stabilization of the formed AgNPs with imprinted GLA crosslinked CHT. The crosslinking process resulted in marked fluorescence enhancement producing hydrogel nanocomposites with a quantum yield of 14% and 24% for Col-MIP and Col-NIP solutions, respectively. A novel Col-MIP stabilized AgNPs sensor solution was successfully prepared and applied for KET detection. The proposed sensors showed linear response over the studied KET concentration range. Both the analytical and calibration sensitivity of the proposed imprinted sensor were compared with nonimprinted and noncross-linked CHT-based sensors. The calibration data were fitted to Stern-Volmer equation, Stern-Volmer constant (KSV) was calculated for each sensor solution and imprinting factor of 0.39 was obtained. The template removal after preparation of the imprinted colloidal solution was not efficient hindering further investigations. Therefore, despite of the numerous advantages of MIP, incomplete template removal negatively affected our developed sensor.