Recent advances and future trends on molecularly imprinted polymer-based fluorescence sensors with luminescent carbon dots.

One of the pressing concerns in analytical chemistry is the construction of selective and sensitive sensors to detect trace analytes in complicated samples. Nowadays, molecularly imprinted polymers (MIPs) that play an important role in most sensing systems are created by molecular imprinting technology (MIT) with tailor-made and synthetic recognition sites, which are complementary in functional groups, size, and shape to the target molecule. Fluorescent carbon dots (CDs), as a new class of carbon-based nanomaterials, have shown simple synthesis, low cost, excellent optical features, great aqueous solubility, and good biocompatibility. Due to the unique properties of recognition specificity, structure predictability, and application universality, the coupling of MIP/CDs with fluorescence detection has attracted great research interest. Accordingly, this review article mainly focuses on the senor designs, sensing mechanisms, and properties of MIP/CDs based fluorescent sensors to various target analytes in most recent years. Finally, we discuss possible future challenges, improvements, and perspectives.

Ultrasound-assisted dispersive solid-phase microextraction of capecitabine by multi-stimuli responsive molecularly imprinted polymer modified with chitosan nanoparticles followed by HPLC analysis.

An ultrasonic-assisted dispersive solid-phase microextraction was developed by a multi-stimuli responsive molecularly imprinted polymer based on chain transfer agent-modified chitosan nanoparticles for enrichment and separation of trace capecitabine in a real sample. The synthesized particles were carefully characterized and it was found that a uniform pH-sensitive imprinted polymeric shell is obtained on the surface of Fe3O4@chitosan core with enough saturation magnetization (29 emu g-1). Desirable adsorption capacity (91 mg g-1) and high imprinting factor (IF = 3.6) toward capecitabine were exhibited by the Langmuir isotherm model. Under optimized conditions, which were achieved by experimental design, the detection limit (S/N = 3) was 1.9 ng mL-1. The obtained relative mean recoveries of capecitabine using high-performance liquid chromatography were in the range of 93 to 102% in a human plasma sample with RSD less than 5.5%. Graphical abstract Schematic representation of ultrasonic-assisted dispersive solid-phase microextraction by multi-stimuli responsive molecularly imprinted polymer based on chain transfer agent-modified chitosan nanoparticles and high-performance liquid chromatography for enrichment and separation of capecitabine in the real sample.

A multi-walled carbon nanotube-based magnetic molecularly imprinted polymer as a highly selective sorbent for ultrasonic-assisted dispersive solid-phase microextraction of sotalol in biological fluids.

A modified multiwalled carbon nanotube-based magnetic molecularly imprinted polymer (MWCNT-MMIP) was synthesized and applied for selective extraction and preconcentration of sotalol (SOT) in biological fluid samples by using ultrasonic-assisted dispersive solid-phase microextraction (UA-DSPME). The synthetic particles were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Brunauer-Emmett-Teller (BET) analysis, vibrating sample magnetometry (VSM) and Fourier transform infrared spectroscopy (FTIR). The screening of UA-DSPME was preliminarily performed by Plackett-Burman design (PBD) and, subsequently, central composite design (CCD) under response surface methodology (RSM) was used individually for evaluation of the significant factors and their possible interaction effects on the adsorption process. Batch mode adsorption studies were performed to evaluate the adsorption kinetics, adsorption isotherms, and selective recognition of MWCNT-MMIPs. The adsorption equilibrium of SOT using MWCNT-MMIPs could be well-defined with the Langmuir isotherm model and the maximum adsorption capacity was calculated to be 79.36 mg g-1. Under optimized conditions, the SOT was selectively and effectively extracted in real biological samples and good linearity was obtained with correlation coefficients (R2) over 0.996 and the detection limit (S/N = 3) was 0.31 ng mL-1. The average recoveries of the spiked human urine and plasma samples at four concentration levels of SOT ranged from 94.60-102.50 and 97.40-101.60 percent, respectively, and the relative standard deviation was found to be lower than 4.50%. The results illustrated that the proposed MWCNT-MMIPs@UA-DSPME extraction method coupled with HPLC-UV determination could be applied for sensitive and selective analysis of trace SOT in biological fluid samples.

Recent configurations and progressive uses of magnetic molecularly imprinted polymers for drug analysis.

Since the introduction of the molecularly imprinting technology (MIT) in the 1970s, it becomes an emerging technology with the potential for wide-ranging applications in drug determination. With the rise of green chemistry, many researchers began to focus on the application and development of green materials which led to the breakthrough of molecularly imprinted polymers (MIPs) in the green chemistry. Because of the low concentration levels in the human matrices, almost adequate analytical methods should be used for quantification of drugs at the trace levels. In recent years there have been reported benefits of combining MIPs with additional features, e.g. magnetic properties, through the build-up of this type of material on magnetite particles. Magnetic molecularly imprinted polymer (MMIP) is a new material which is composed of magnetic material and non-magnetic polymer material and shares the characteristics of high adsorption capacity to template molecule, special selective recognition ability, and the magnetic adsorption property. These materials have been widely used in the different fields such as chemical, biological and medical science. This review describes the novel configurations and progressive applications of magnetic molecularly imprinted polymers to the drug analysis. Also, the advantages and drawbacks of each methodology, as well as the future expected trends, are evaluated.

Recent progress, challenges and trends in trace determination of drug analysis using molecularly imprinted solid-phase microextraction technology.

The quantification of drugs in biological samples is a significant task for determination of the physiological efficiency in evaluated drugs in the drug discovery. To analysis of the chemical compounds at the trace and ultratrace levels, adequate analytical procedures should be applied. Therefore, sample preparation method undoubtedly is the most important stage in the trace determination process. In spite of the great growth of analytical instrumentation during the recent years, sample preparation is still nowadays considered the impasse of the all analytical procedure, especially in drugs analysis. Because of the low concentration level of drugs in blood, plasma, and the diversity of the metabolites, the chosen extraction technique should be almost perfect. Solid-phase microextraction (SPME) is a powerful, simple, fast and an equilibrium-based sample preparation method that permits integration of sampling, sample clean-up, and pre-concentration in a single solvent-free step for chemical analysis. Molecularly imprinted polymers (MIPs) that provided by the presence of a template during their synthesis are the stable polymers with molecular recognition abilities and excellent materials which provide selectivity to sample preparation. Because of its characteristics such as easy preparation, high selectivity, and chemical stability, MIP is widely utilized in many analytical fields. Accordingly, the molecular imprinting and SPME methods combination would prepare a strong analytical instrumentation which comprises simplicity, flexibility, and the selectivity characteristics of both methods. This review focuses on the application of solid-phase microextraction method coupled with molecularly imprinted polymers, namely molecularly imprinted solid-phase microextraction (MISPME), for trace determination in drug analysis.