Highly selective solid phase extraction and preconcentration of Azathioprine with nano-sized imprinted polymer based on multivariate optimization and its trace determination in biological and pharmaceutical samples

Synthesis of a magnetic SBA-15-NH2@Dual-Template Imprinted Polymer for solid phase extraction and determination of Pb and Cd in vegetables; Box Behnken design

In this study, a simple one-step method was applied for extraction and determination of lead and cadmium. The significant variables in extraction and pre-concentration were identified using analysis of variance and their behavior was modeled. Dual-template imprinted polymer was synthesized on modified Mesoporous silica structures coated with Fe₃O₄ magnetic nanoparticles. The optimum condition was 6.12 for pH, 40.62 mg for the polymer amount and 17.38 for the ultrasonic time. Concentration range, correlation coefficient, limit of detection and relative standard deviation for lead were reported to be 0.5-950, 0.9988, 0.35 μg L^-1 and 3.5%, respectively. For cadmium the above mentioned figure of merits were 0.3-980, 0.9969, 0.15 μg L^-1 and 2.4%, respectively. The adsorption capacities for lead and cadmium were reported to be 10.28 and 10.38, while their imprinting factors were 5.89 and 6.36, respectively.

The Use of Computational Methods for the Development of Molecularly Imprinted Polymers

Recent years have witnessed a dramatic increase in the use of theoretical and computational approaches in the study and development of molecular imprinting systems. These tools are being used to either improve understanding of the mechanisms underlying the function of molecular imprinting systems or for the design of new systems. Here, we present an overview of the literature describing the application of theoretical and computational techniques to the different stages of the molecular imprinting process (pre-polymerization mixture, polymerization process and ligand-molecularly imprinted polymer rebinding), along with an analysis of trends within and the current status of this aspect of the molecular imprinting field.

Synthesis and characterization of a molecularly imprinted polymer (MIP) for solid-phase extraction of the antidiabetic gliclazide from human plasma

Gliclazide is a sulfonylurea frequently prescribed for the management of type 2 diabetes mellitus in elderly patients and for patients with chronic renal or hepatic diseases. Even though it is considered a safer alternative, the drug can provoke side effects in some patients, especially hypoglycemia, due to the high interindividual variability. Therefore, the quantification of gliclazide in biological samples is usually recommended in order to assure efficacy and safety of the pharmacotherapy. However, due to the complexity of biological matrices, therapeutic monitoring can be very challenging, especially in the sample preparation step. For that reason, the synthesis and characterization of a novel and selective molecularly imprinted polymer (MIP) was proposed to be employed as sorbent for the extraction of gliclazide from human plasma samples by a molecularly imprinted solid-phase extraction (MISPE) procedure. Synthesis conditions were optimized (monomer, crosslinker and porogen) and the polymer was characterized for its morphological, physicochemical and stability properties. The influence of drug concentration, solvent composition and pH on the coefficient of distribution (K_d) and imprinting factor (IF) were studied, as well as repeatability between batches and selectivity. A bioanalytical method was developed applying the developed MIP as sorbent in solid phase extraction and liquid chromatography using a Poroshell 120 C18 (100 × 4.6 mm, 4 μm) column, acetonitrile and 10 mM potassium phosphate buffer pH 3.0 (50:50) at a flow-rate of 1.2 mL/min as mobile phase, temperature of 30 °C, injection volume of 40 μL and detection at 230 nm. The best reaction yield, extraction capacity, and selectivity was obtained using 2-hydroxyethyl methacrylate (2-HEMA), ethyleneglycol dimethacrylate (EGDMA) and acetonitrile. The optimized MIP showed coefficient of distribution (K_d) of 59.85 μg/g, imprinting factor (IF) of 1.60, and selectivity for gliclazide and other sulfonylureas compared to possible concurrent drugs. The developed method by MISPE-HPLC-UV showed to be appropriate to determine gliclazide in human plasma samples.

Pharmacokinetic Profiling and Simultaneous Determination of Thiopurine Immunosuppressants and Folic Acid by Chromatographic Methods

With the increase in the number of medicines patients have to take, there has been a rapid rise of fixed-dose combinations (FDCs) in the last two decades. Prior to FDC development, pharmacokinetic properties of active pharmaceutical ingredients (APIs) have to be evaluated, as well as methods for their determination developed. So as to increase patient compliance in inflammatory bowel disease, three novel FDCs of thiopurine immunosuppressants and folic acid are proposed; physico-chemical and pharmacokinetic properties such as hydrophobicity, lipophilicity and plasma protein binding of all APIs are evaluated. Moreover, experimental results of different properties are compared to those computed by various on-line prediction platforms so as to evaluate the viability of the in silico approach. A simultaneous method for their determination is developed, optimized, validated and applied to commercial tablet formulations. The method has shown to be fast, selective, accurate and precise, showing potential for reliable determination of API content in proposed FDCs during its development.

Synthesis of a polymeric imidazolium-embedded octadecyl ionic liquid-grafted silica sorbent for extraction of flavonoids

In this work, a polymeric imidazolium-embedded octadecyl ionic liquid (poly(1-vinyl-3-octadecylimidazolium naphthalene sulfonate))-grafted silica (poly(C₁₈VIm⁺NapSO₃^-)@SiO₂) sorbent was prepared and applied as a solid-phase extraction (SPE) sorbent in extraction of flavonoids. The synthesized poly(C₁₈VIm⁺NapSO₃^-)@SiO₂ sorbent was characterized by X-ray photoelectron spectrogram (XPS) and fourier transform infrared spectroscopy (FT-IR). The thermodynamic and kinetic adsorption models of the prepared poly(C₁₈VIm⁺NapSO₃^-)@SiO₂ sorbent towards flavonoids were discussed by nonlinear fitting adsorption curve and the results indicated the thermodynamic adsorption model in this work was tended to be Freundlich model rather than Langmuir one and the pseudo-second order model could be used to describe the dynamic adsorption process. In addition, the adsorption amounts indicated the sorbent has satisfactory extraction capabities towards flavonoids. For investigating the influence of independent variables and their interactions on the extraction efficiency, a Box-Behnken design was used for optimizing three greatly influential parameters after performing single-factor experiments. The interaction energies between flavonoids and two ionic liquids were calculated to understand the adsorption mechanism. Under the optimal conditions, a method used for determining flavonoids was developed by combining SPE technique with high performance liquid chromatography (HPLC), and the developed method exhibited low limits of detection (0.25-0.4 μg L^-1), good linearities with correlation coefficients (R²) in the range of 0.9951-0.9996 and satisfactory recoveries ranging from 83.6% to 114.1%, which confirmed the proposed method could be successfully used to determine trace flavonoids in real samples.