Analysis of nicotine and its oxidation products in nicotine chewing gum by a molecularly imprinted solid-phase extraction

Recent advances in the removal of emerging contaminants from water by novel molecularly imprinted materials in advanced oxidation processes-A review

Recently, there has been a global focus on effectively treating emerging contaminants (ECs) in water bodies. Advanced oxidation processes (AOPs) are the primary technology used for ECs removal. However, the low concentrations of ECs make it difficult to overcome the interference of background substances in complex water quality, which limits the practical application of AOPs. To address this limitation, many researchers are developing new catalysts with preferential adsorption. Molecular imprinting technology (MIT) combined with conventional catalysts has been found to effectively enhance the selectivity of catalysts for the targeted catalytic degradation of pollutants. This review presents a comprehensive summary of the progress made in research on molecularly imprinted polymers (MIPs) in the selective oxidation of ECs in water. The preparation methods, principles, and control points of novel MIP catalysts are discussed. Furthermore, the performance and mechanism of the catalysts in photocatalytic oxidation, electrocatalytic oxidation, and persulfate activation are analyzed with examples. The possible ecotoxicological risks of MIP catalysts are also discussed. Finally, the challenges and prospects of applying MIP catalysts in AOP are presented along with proposed solutions. This review provides a better understanding of using MIP catalysts in AOPs to target the degradation of ECs.

Advancing the use of molecularly imprinted polymers in bioanalysis: the selective extraction of cotinine in human urine

Aim: To characterize a molecularly imprinted polymer via precipitation polymerization for the extraction of cotinine in urine. Methods: The polymer was created via precipitation polymerization. Physical characteristics of the polymer were assessed via scanning electron microscopy, Fourier transform infrared spectroscopy and thermogravimetric analysis. The polymer adsorption capacity was assessed and an solid-phase extraction method from urine by LC-MS/MS was developed. Results: The polymer had small, spherical morphology and little thermal decomposition. The extraction method yielded cotinine recoveries of 77-103% in urine. The molecularly imprinted polymer adsorption capacity for cotinine was 448.2 ± 2.1 μg/mg. Common interferants did not affect cotinine's extraction. Conclusion: The resulting polymer was determined to be specific for cotinine and can be used for the detection of cotinine in urine for clinical samples.

Raman Imaging as a powerful tool to elucidate chemical processes in a matrix: Medicated chewing gums with nicotine

Extruded medicated chewing gum is a convenient but complex drug delivery system. Description of gum ingredient distribution and interactions in literature is sparse, but fundamental in product characterization and stability prediction. Although Raman spectroscopy has been used for such characterization of numerous dosage forms, its applicability to medicated chewing gum has not been studied until now. The objective was to investigate the applicability of confocal Raman imaging on chewing gum for identification and distribution of excipients and the model drug nicotine, including changes occurring during shelf life. A sample preparation protocol was composed to present an even surface of a gum cross section without altering the gum matrix texture. High-resolution Raman maps were obtained by Non Negative Least Squares (NNLS) analysis for a reference gum and gums stored for 6 months at mild (25 °C/60% RH) and accelerated (40 °C/75% RH) conditions. Additional Empty Modelling™ analysis confirmed the results of NNLS. The NNLS analysis located nicotine and the following excipients: gum base, calcium carbonate, sorbitol, xylitol, sodium carbonate, sodium bicarbonate and talc in distinct domains of the reference sample. Changes of the sample stored at accelerated conditions was discovered as sodium carbonate was not observed in this sample. Additionally, stereo light microscopy showed changes in product appearance and high-performance liquid chromatography confirmed formation of the oxidation product nicotine-1'-N-oxide in this sample. The gum formulation and its ingredients displayed characteristic Raman spectra, proving Raman imaging as a useful method for characterizing medicated chewing gums, including changes occurring during stability testing.

Solid-Phase Extraction of Active Compounds from Natural Products by Molecularly Imprinted Polymers: Synthesis and Extraction Parameters

Molecularly imprinted polymers (MIPs) are synthetic polymers with a predetermined selectivity for a particular analyte or group of structurally related compounds, making them ideal materials for separation processes. Hence, in sample preparation, MIPs are chosen as an excellent material to provide selectivity. Moreover, its use in solid-phase extraction, also referred to as molecular imprinted solid phase extraction (MISPE), is well regarded. In recent years, many papers have been published addressing the utilization of MIPs or MISPE as sorbents in natural product applications, such as synthesis. This review describes the synthesis and characterization of MIPs as a tool in natural product applications.

Green molecularly imprinted polymers for sustainable sample preparation

The use of molecularly imprinted polymers in sample preparation as selective sorbent materials has received great attention during the last years leading to analytical methods with unprecedented selectivity. However, with the progressive implementation of Green Analytical Chemistry principles, it is necessary to critically review the greenness of synthesis and further use of molecularly imprinted polymers in sample preparation. Accordingly, in the present review, the different steps and strategies for the preparation of molecularly imprinted polymers, the used reagents, as well as their incorporation to microextraction techniques are reviewed from a green perspective and recent alternatives to make the use of molecularly imprinted polymers more sustainable are provided.

Molecularly imprinted polymers as a selective sorbent for forensic applications in biological samples-a review

Molecularly imprinted polymers (MIP) consist of a molecular recognition technology with applicability in different areas, including forensic chemistry. Among the forensic applications, the use of MIP in biological fluid analysis has gained prominence. Biological fluids are complex samples that generally require a pre-treatment to eliminate interfering agents to improve the results of the analyses. In this review, we address the development of this molecular imprinting technology over the years, highlighting the forensic applications of molecularly imprinted polymers in biological sample preparation for analysis of stimulant drugs such as cocaine, amphetamines, and nicotine.

The Importance of Developing Electrochemical Sensors Based on Molecularly Imprinted Polymers for a Rapid Detection of Antioxidants

This review aims to pin out the importance of developing a technique for rapid detection of antioxidants, based on molecular imprinting techniques. It covers three major areas that have made great progress over the years in the field of research, namely: antioxidants characterization, molecular imprinting and electrochemistry, alone or combined. It also reveals the importance of bringing these three areas together for a good evaluation of antioxidants in a simple or complex medium, based on selectivity and specificity. Although numerous studies have associated antioxidants with molecular imprinting, or antioxidants with electrochemistry, but even electrochemistry with molecular imprinting to valorize different compounds, the growing prominence of antioxidants in the food, medical, and paramedical sectors deserves to combine the three areas, which may lead to innovative industrial applications with satisfactory results for both manufacturers and consumers.

Molecularly Imprinted Polymer (MIP) Applications in Natural Product Studies Based on Medicinal Plant and Secondary Metabolite Analysis

Characterization and extraction of plant secondary metabolites are important in agriculture, pharmaceutical, and food industry. In this regard, the applied analytical methods are mostly costly and time-consuming; therefore, choosing a suitable approach is essential for optimum results and economic suitability. One of the recently considered methods used to characterize new types of materials is MIPs. Among the various applications of MIPs is the identification and separation of various plant-derived compounds, such as secondary metabolites, chemical residues, and pesticides. The present review describes the application of MIPs as a tool in medicinal plant material analysis, focusing on plant secondary metabolism.

Exploring Matrix Effects on Binding Properties and Characterization of Cotinine Molecularly Imprinted Polymer on Paper-Based Scaffold

Commercially available sorbent materials for solid-phase extraction are widely used in analytical laboratories. However, non-selective binding is a major obstacle for sample analysis. To overcome this problem, molecularly imprinted polymers (MIPs) were used as selective adsorbent materials prior to determining target analysts. In this study, the use of non-covalent molecularly imprinted polymers (MIPs) for cotinine adsorption on a paper-based scaffold was studied. Fiberglass paper was used as a paper scaffold for cotinine-selective MIP adsorption with the use of 0.5% agarose gel. The effects of salt, pH, sample matrix, and solvent on the cotinine adsorption and extraction process were investigated. Under optimal conditions, the adsorption isotherm of synthesized MIPs increased to 125.41 µg/g, whereas the maximum adsorption isotherm of non-imprinted polymers (NIPs) was stable at 42.86 µg/g. The ability of the MIP paper scaffold to absorb cotinine in water medium was approximately 1.8–2.8-fold higher than that of the NIP scaffold. From Scatchard analysis, two dissociation constants of MIPs were calculated to be 2.56 and 27.03 µM. Nicotine, myosmine, and N-nitrosonornicotine were used for selectivity testing, and the calculated selectivity factor of cotinine to nicotine, myosmine, and N-nitrosonornicotine was 1.56, 2.69, and 2.05, respectively. Overall, the MIP paper scaffold is promising for simple onsite sampling of cotinine and can be used to assess tobacco smoke exposure.

Selective removal of nicotine from the main stream smoke by using a surface-imprinted polymer monolith as adsorbent

Using molecularly imprinted polymer as a selective adsorbent for gaseous toxicants is a novel attempt. In present work, a nicotine surface-imprinted monolith (MIM) was used for the selective removal of nicotine from smoke. First, the retention capacity and selectivity for this MIM was tested by using it as the stationary phase in gas chromatography and chromatographic conditions optimized. Then, the gas phase adsorption isotherms of MIM were constructed and the adsorption thermodynamics explored. At last, the applicability for MIM in the removal of nicotine in smoke was explored. Results indicated a stronger retention capacity and a higher selectivity of MIM toward the template vapor, with a capacity factor (87.88) and a selectivity factor (10.15) under the optimized conditions. A higher standard adsorption enthalpy change for this MIM toward the template (ΔH_a⁰ = 65.53 kJ mol^-1) than that for the non-imprinted monolith (NIM) column (ΔH_a⁰ = 47.46 kJ mol^-1) was observed. The adsorption isotherm for MIM appears the BET type II shape, while that for the NIM was approximately linear. When this MIM was used as the adsorbent, it exhibited a high performance in the selective removal of nicotine from the main stream smoke, with an adsorption percentage of 99.43%.

Preparation and Evaluation of Oseltamivir Molecularly Imprinted Polymer Silica Gel as Liquid Chromatography Stationary Phase

To improve the chromatographic performance of an oseltamivir (OS) molecularly imprinted polymer (MIP), silica gel coated with an MIP layer for OS (OSMIP@silica gel) was prepared by the surface molecular imprinting technology on the supporter of porous silica gel microspheres. A nonimprinted polymer with the silica gel (NIP@silica gel) was also prepared for comparison. The obtained particles were characterized through FT–IR, scanning electron microscopy, specific surface area analysis, and porosity measurements. The results indicated that the polymer was successfully synthesized and revealed the structural differences between imprinted and nonimprinted polymers. The results of static adsorption experiments showed that adsorption quantity of the OSMIP@silica gel for OS was higher than that for NIP@silica gel, and the OSMIP@silica gel had two kinds of affinity sites for OS but the NIP@silica gel had one. The chromatographic performance of the OSMIP@silica gel column had significant improvement. The imprinting factor of the OSMIP@silica gel column for OS was 1.64. Furthermore, the OSMIP@silica gel column showed good affinity and selectivity for template OS and another neuraminidase inhibitor, peramivir, but not for quinocetone. These results indicated that the prepared OSMIP could be used to simulate the activity center of neuraminidase, and the OSMIP@silica gel column could be also employed in future studies to search for more active neuraminidase inhibitor analogues from traditional Chinese herbs.

Molecular Imprinting Applications in Forensic Science

Producing molecular imprinting-based materials has received increasing attention due to recognition selectivity, stability, cast effectiveness, and ease of production in various forms for a wide range of applications. The molecular imprinting technique has a variety of applications in the areas of the food industry, environmental monitoring, and medicine for diverse purposes like sample pretreatment, sensing, and separation/purification. A versatile usage, stability and recognition capabilities also make them perfect candidates for use in forensic sciences. Forensic science is a demanding area and there is a growing interest in molecularly imprinted polymers (MIPs) in this field. In this review, recent molecular imprinting applications in the related areas of forensic sciences are discussed while considering the literature of last two decades. Not only direct forensic applications but also studies of possible forensic value were taken into account like illicit drugs, banned sport drugs, effective toxins and chemical warfare agents in a review of over 100 articles. The literature was classified according to targets, material shapes, production strategies, detection method, and instrumentation. We aimed to summarize the current applications of MIPs in forensic science and put forth a projection of their potential uses as promising alternatives for benchmark competitors.

Surface Plasmon Resonance-Based Fiber Optic Sensors Utilizing Molecular Imprinting

Molecular imprinting is earning worldwide attention from researchers in the field of sensing and diagnostic applications, due to its properties of inevitable specific affinity for the template molecule. The fabrication of complementary template imprints allows this technique to achieve high selectivity for the analyte to be sensed. Sensors incorporating this technique along with surface plasmon or localized surface plasmon resonance (SPR/LSPR) provide highly sensitive real time detection with quick response times. Unfolding these techniques with optical fiber provide the additional advantages of miniaturized probes with ease of handling, online monitoring and remote sensing. In this review a summary of optical fiber sensors using the combined approaches of molecularly imprinted polymer (MIP) and the SPR/LSPR technique is discussed. An overview of the fundamentals of SPR/LSPR implementation on optical fiber is provided. The review also covers the molecular imprinting technology (MIT) with its elementary study, synthesis procedures and its applications for chemical and biological anlayte detection with different sensing methods. In conclusion, we explore the advantages, challenges and the future perspectives of developing highly sensitive and selective methods for the detection of analytes utilizing MIT with the SPR/LSPR phenomenon on optical fiber platforms.

A novel electrochemical nicotine sensor based on cerium nanoparticles with anionic surfactant

A novel promising electrochemical nicotine (NIC) sensor was prepared by electrodeposition of Ce-Nanoparticles on a carbon paste electrode (CPE).

Solid phase extraction of doxorubicin using molecularly imprinted polymer coated magnetite nanospheres prior to its spectrofluorometric determination

Selective doxorubicin-imprinted polymer coated magnetite nanospheres were synthesized.

Targeted extraction of active compounds from natural products by molecularly imprinted polymers

One of the most promising separation techniques that have emerged during the last decade is based on the use of molecularly imprinted polymers (MIPs). MIPs are stable polymers that possess specific cavities designed for a template molecule, endowed with excellent selectivity compared to regular solid phase extraction techniques. Molecularly imprinted solid-phase extraction (MISPE) has already shown a high efficiency for the sample preparation from complex matrices. Natural products received huge attention in recent years. Indeed, the application of MISPE for the screening of natural products appears extremely interesting not only for the selective extraction of a target compound but also for the concomitant discovery of new drug candidates, promising sources of therapeutic benefits. In the present review, examples of recognition and separation of active components from natural extracts are emphasized. MIPs are very promising materials to mimic the recognition characteristics exhibited by enzymes or receptors although further developments are necessary to fully exploit their wide potential.

Ultrasonic extraction of phenols from olive mill wastewater: comparison with conventional methods

Recovery of phenols from olive mill wastewater (OMWW) was studied, comparing five sample preparation methods: filtration, solid-phase (SPE), liquid-liquid (LLE) and ultrasonic (US)-assisted extraction of liquid and solid (freeze-dried) OMWW. Results showed that ultrasonication is a good alternative to conventional solvent extractions, providing higher recoveries at both levels of individual and total phenol yields. Sonication of liquid OMWW in organic solvent was more efficient vs its nonassisted counterpart (agitation), but did not provide a representative phenol chromatogram due to ethyl acetate use. By contrast, the US-assisted extraction of freeze-dried OMWW (3 × 20 min) in 100% methanol (1.5 g/25 mL, w/v) offered the highest qualitative-quantitative phenol yields without any US-induced alterations. Moreover, freeze-drying is an excellent preservation of initial liquid OMWW, holding a great potential for delayed analysis. This study is also the first report that Slovenian OMWW may be utilized as a valuable source of phenols, especially hydroxytyrosol and tyrosol.

Preparation and utilization of a molecularly imprinted polymer for solid phase extraction of tramadol

In this paper, a highly selective molecularly imprinted polymer (MIP) for tramadol hydrochloride, a drug used to treat moderate to severe pain, was prepared and its use as solid-phase extraction (SPE) sorbent was demonstrated. The molecularly imprinted solid-phase extraction procedure followed by high performance liquid chromatography with ultraviolet detector (MISPE-HPLC) was developed for selective extraction and determination of tramadol in human plasma and urine. The optimal conditions for molecularly imprinted solid-phase extraction (MISPE) consisted of conditioning with 1 mL methanol and 1 mL of deionized water at neutral pH, loading of tramadol sample (50 µg L−1) at pH 7.5, washing using 1 mL acetone and elution with 3 × 1 mL of 10% (v/v) acetic acid in methanol. The MIP selectivity was evaluated by checking several substances with similar molecular structures to that of tramadol. Results from the HPLC analyses showed that the calibration curve of tramadol (using MIP from human plasma and urine) is linear in the ranges of 6–100 and 3–120 µg L−1 with good precisions (1.9% and 2.9% for 5.0 µg L−1), respectively. The recoveries for plasma and urine samples were higher than 81%.

Uptake of nicotine from suspension culture of Nicotiana tabacum by molecularly imprinted polymers

OBJECTIVES

The aim was to use molecularly imprinted polymers (MIPs) for the selective recovery of nicotine in plant cell cultures. MIPs can selectively uptake nicotine from suspension cultures of N. tabacum, and therefore may be useful for improving levels of secondary metabolites in plant cell cultures.

METHODS

Suspension cultures of N. tabacum were initiated from callus and maintained in liquid Murashige and Skoog (MS) media containing 3% w/v sucrose, 0.1 mg/l alpha-naphthaleneacetic acid acid (NAA) and 0.25 mg/l kinetin. Tween 80 at 1% was used for permeabilisation of cell cultures. Pre-weighed XAD-2 and two types of synthesized polymers, MIPs (A and B with one and two functional monomers, respectively) and corresponding non-imprinted polymers (NIPs), A and B, were introduced aseptically into the permeabilised suspension cultures of N. tabacum, the nicotine contents of polymers were determined by gas chromatography and the adsorption yield of polymers were determined.

KEY FINDINGS

Cell cultures of N. tabacum accumulated nicotine alkaloid intracellularly in varying levels, 6.8-14.9 mg/l fresh weight. MIPs were able to uptake 50-70% of released nicotine in suspension cultures of N. tabacum, whereas XAD-2 recovered only 30-40%. The total levels of accumulated nicotine were enhanced up to 20 mg/l by simultaneous use of Tween 80 and MIPs.

CONCLUSIONS

The findings indicate the potential use of MIPs to uptake nicotine from suspension cultures of N. tabacum, and increase productivity of secondary metabolites in plant cell cultures.