Molecularly imprinted electrospun nanofibre membrane assisted stir bar sorptive extraction for trace analysis of sulfonamides from animal feeds

Recent advances in molecular-imprinting-based solid-phase microextraction for determination of pharmaceutical residues

Pharmaceutical residues usually exist in various complicated matrices at trace levels, but pose potential threats to human health and ecological environment. Recognition and determination of the residues are important and urgent. Therefore, efficient sample pretreatment techniques become a research hotspot for the sensitive and precise determination by chromatography and mass spectrometry. Molecular-imprinting-based solid-phase microextraction (MI-SPME) combines the rapidity, high enrichment and solvent-free property of SPME with the specific recognition and selective adsorption ability of molecularly imprinted polymers (MIPs), and shows significant advantages in the highly selective separation and enrichment of drug residues in complex samples. Herein, we review recent advances in MI-SPME for determination of pharmaceutical residues since 2019. Firstly, the basic characteristics and operation process of SPME are briefly introduced, and then the polymerization methods of MIPs including free radical polymerization, in-situ polymerization and sol-gel polymerization, and new imprinting technologies and strategies including surface imprinting, nano-imprinting, dummy template, multi-template/functional monomer imprinting and stimuli-responsive imprinting, are comprehensively overviewed. Then, various modes of MI-SPME device are meticulously discussed, mainly including MIPs-coated fiber SPME, MIPs-based in-tube SPME, dispersible SPME, MIPs in-tip SPME, MIPs stir bar sorptive extraction, and MIPs thin film microextraction. Subsequently, typical application cases of MI-SPME coupled with chromatography and mass spectrometry for the determination of drug residues are summarized, in the fields of food safety, biological medicine and environmental monitoring, specially mentioning chiral drug detection and matrix effects and interferences. Finally, the possible challenges of MI-SPME in drug residue detection are presented, and the research prospects and development trends of MI-SPME are proposed.

Utilizing electrospun molecularly imprinted membranes for food industry: Opportunities and challenges

Molecularly imprinted polymers (MIPs) have been widely studied in environmental protection and food industry, owing to their excellent specific recognition and structural stability. However, MIPs prepared by conventional methods suffer from low adsorption capacity and slow mass transfer rate. To date, the combination of electrostatic spinning technology and molecular imprinting technology has been proposed to prepare molecularly imprinted membranes (MIMs) with specific recognition capability, and has shown great attraction in the separation and detection of food additives, as well as the extraction and release of active ingredients. In recent years, MIPs and electrostatic spinning technologies have been investigated and evaluated. However, there is no review of electrostatically spun MIMs for food field. In this review, we focus on the fabrication methods and applications of electrostatically spun MIMs in the food, discuss the challenges in practical food applications, and emphasize the promising applications of electrostatically spun MIMs in food field.

Sensitive extraction of seven pesticide residues from environmental water with magnetic graphene oxide-based covalent organic framework

The use of pesticides has increased with the development of agriculture. However, due to the trace content and the matrix's inherent complexity in environmental water, development of rapid and sensitive detection method present significant challenges in the analysis of pesticide residues. The study synthesized magnetic graphene oxide (MGO) by combining superparamagnetic nanoparticles with the easy modification of graphene oxide (GO). Covalent organic frameworks (COFs) were then modified to have a large specific surface area. Finally, magnetic graphene oxide-based covalent organic frameworks, namely MGO-COFs, were obtained with a spherical structure and used as magnetic solid-phase extraction materials, which was successfully used to determine the seven pesticide residues in environmental samples in conjunction with high performance liquid chromatography. The method has a wide linear range for the tested pesticides, with satisfactory correlation coefficients (R ≥ 0.099) and low detection limits (0.3-1.21 μg L-1). The correlation coefficients for all seven pesticides were high (R2 ≥ 0.9996). The spiked recoveries, exhibiting a range of 91.3 to 109 %, demonstrated that the developed MGO-COF-MSPE-HPLC-UV method is simple, efficient, and suitable for the analysis and detection of seven pesticide residues in environmental water.

Assessing antibiotic residues in sediments from mangrove ecosystems: A review

Antibiotics' widespread and abusive use in aquaculture and livestock leads to extensive environmental dissemination and dispersion, consequently increasing antibiotic-resistant bacteria in marine ecosystems. Hence, there is an increased need for efficient methods for identifying and quantifying antibiotic residues in soils and sediments. From a review of the last 20 years, we propose and compare different chromatographic techniques for detecting and quantifying antibiotics in sediment samples from marine ecosystems, particularly in mangrove forest sediments. The methods typically include three stages: extraction of antibiotics from the solid matrix, cleaning, and concentration of samples before quantification. We address the leading causes of the occurrence of antibiotics in marine ecosystem sediments and analyze the most appropriate methods for each analytical stage. Ultimately, selecting a method for identifying antibiotic residues depends on multiple factors, ranging from the nature and physicochemical properties of the analytes to the availability of the necessary equipment and the available resources.

Removal of bromophenol blue from polluted water using a novel azo-functionalized magnetic nano-adsorbent

Water pollution from organic dyes poses a serious danger to the environment. In the present work, we report a novel adsorbent (ADFS) based on azo-dye-functionalized superparamagnetic iron oxide nanoparticles (SPIONs) for the removal of the anionic dye bromophenol blue (BPB) from contaminated water. The fabricated SPIONs, azo dye, and ADFS adsorbent were characterized with FTIR and UV-vis absorption spectroscopy, 1HNMR spectroscopy, mass spectrometry, SEM imaging, dynamic light scattering (DLS), zeta potential measurements, vibrating sample magnetometry, thermogravimetric analysis, differential thermal analysis, and X-ray diffraction analysis. DLS measurements showed a particle size of 46.1 and 176.5 nm for the SPIONs and the ADFS, respectively. The adsorbent exhibited an adsorption capacity of 7.43 mg g-1 and followed the pseudo-second-order kinetics model (r2 = 0.9981). The ADFS could efficiently remove BPB from water after stirring for 120 minutes at room temperature and pH 2. The adsorption process was proved to occur via physisorption, as revealed by the Freundlich isotherm (n = 1.82 and KF = 11.5). Thermodynamic studies implied that the adsorption is spontaneous (-8.03 ≤ ΔG ≤ -0.58 kJ mol-1) and enthalpy-driven might take place via van der Waals interactions and/or hydrogen bonding (ΔH = -82.19 kJ mol-1 and ΔS = -0.24 kJ mol-1 K-1).

A nanocellulose molecularly imprinted membrane: Preparation, characterization and application in targeted separation of taxane 10-deacetylbaccatin III

Targeted separation of active phytochemicals is urgently needed in the natural medicine field. In this paper, due to the natural porosity and high biocompatibility of cellulose, a nanocellulose membrane combined with surface molecular imprinting was successfully prepared; the efficient nanocellulose-based molecular imprinted membrane (NC-MIM) provided good adsorption for the targeted separation of phytochemicals such as 10-deacetylbaccatin III (10-DAB), an essential intermediate in the synthesis of the anticancer drug paclitaxel. Through a series of characterization and adsorption experiments, the adsorption mechanism of NC-MIM was determined. At pH 8.0 and temperatures of 20 °C-40 °C, the maximum capacity of NC-MIM for adsorption of 10-DAB reached 66.90 mg g - 1, and the content of 10-DAB was dramatically increased 17.5-fold after adsorption. The specific adsorption results showed that NC-MIM had excellent capacity for targeted separation of 10-DAB from among taxane structural analogues. Even after ten cycles, NC-MIM demonstrated a remarkable adsorption capacity of 86.43%, thereby indicating exceptional selectivity and stability. The successful implementation of NC-MIM for green, safe, and efficient enrichment of phytochemicals from plants provides a promising new approach and valuable insights into its practical application.

Advanced Development of Molecularly Imprinted Membranes for Selective Separation

Molecularly imprinted membranes (MIMs), the incorporation of a given target molecule into a membrane, are generally used for separating and purifying the effective constituents of various natural products. They have been in use since 1990. The application of MIMs has been studied in many fields, including separation, medicine analysis, solid-phase extraction, and so on, and selective separation is still an active area of research. In MIM separation, two important membrane performances, flux and permselectivities, show a trade-off relationship. The enhancement not only of permselectivity, but also of flux poses a challenging task for membranologists. The present review first describes the recent development of MIMs, as well as various preparation methods, showing the features and applications of MIMs prepared with these different methods. Next, the review focuses on the relationship between flux and permselectivities, providing a detailed analysis of the selective transport mechanisms. According to the majority of the studies in the field, the paramount factors for resolving the trade-off relationship between the permselectivity and the flux in MIMs are the presence of effective high-density recognition sites and a high degree of matching between these sites and the imprinted cavity. Beyond the recognition sites, the membrane structure and pore-size distribution in the final imprinted membrane collectively determine the selective transport mechanism of MIM. Furthermore, it also pointed out that the important parameters of regeneration and antifouling performance have an essential role in MIMs for practical applications. This review subsequently highlights the emerging forms of MIM, including molecularly imprinted nanofiber membranes, new phase-inversion MIMs, and metal-organic-framework-material-based MIMs, as well as the construction of high-density recognition sites for further enhancing the permselectivity/flux. Finally, a discussion of the future of MIMs regarding breakthroughs in solving the flux-permselectivity trade-off is offered. It is believed that there will be greater advancements regarding selective separation using MIMs in the future.

Recent Advances in Molecularly Imprinted Polymers for Antibiotic Analysis

The abuse and residues of antibiotics have a great impact on the environment and organisms, and their determination has become very important. Due to their low contents, varieties and complex matrices, effective recognition, separation and enrichment are usually required prior to determination. Molecularly imprinted polymers (MIPs), a kind of highly selective polymer prepared via molecular imprinting technology (MIT), are used widely in the analytical detection of antibiotics, as adsorbents of solid-phase extraction (SPE) and as recognition elements of sensors. Herein, recent advances in MIPs for antibiotic residue analysis are reviewed. Firstly, several new preparation techniques of MIPs for detecting antibiotics are briefly introduced, including surface imprinting, nanoimprinting, living/controlled radical polymerization, and multi-template imprinting, multi-functional monomer imprinting and dummy template imprinting. Secondly, several SPE modes based on MIPs are summarized, namely packed SPE, magnetic SPE, dispersive SPE, matrix solid-phase dispersive extraction, solid-phase microextraction, stir-bar sorptive extraction and pipette-tip SPE. Thirdly, the basic principles of MIP-based sensors and three sensing modes, including electrochemical sensing, optical sensing and mass sensing, are also outlined. Fourthly, the research progress on molecularly imprinted SPEs (MISPEs) and MIP-based electrochemical/optical/mass sensors for the detection of various antibiotic residues in environmental and food samples since 2018 are comprehensively reviewed, including sulfonamides, quinolones, β-lactams and so on. Finally, the preparation and application prospects of MIPs for detecting antibiotics are outlined.

Recent molecularly imprinted polymers applications in bioanalysis

Molecular imprinted polymers (MIPs) as extraordinary compounds with unique features have presented a wide range of applications and benefits to researchers. In particular when used as a sorbent in sample preparation methods for the analysis of biological samples and complex matrices. Its application in the extraction of medicinal species has attracted much attention and a growing interest. This review focus on articles and research that deals with the application of MIPs in the analysis of components such as biomarkers, drugs, hormones, blockers and inhibitors, especially in biological matrices. The studies based on MIP applications in bioanalysis and the deployment of MIPs in high-throughput settings and optimization of extraction methods are presented. A review of more than 200 articles and research works clearly shows that the superiority of MIP techniques lies in high accuracy, reproducibility, sensitivity, speed and cost effectiveness which make them suitable for clinical usage. Furthermore, this review present MIP-based extraction techniques and MIP-biosensors which are categorized on their classes based on common properties of target components. Extraction methods, studied sample matrices, target analytes, analytical techniques and their results for each study are described. Investigations indicate satisfactory results using MIP-based bioanalysis. According to the increasing number of studies on method development over the last decade, the use of MIPs in bioanalysis is growing and will further expand the scope of MIP applications for less studied samples and analytes.

Theoretical insights into the uptake of sulfonamides onto phospholipid bilayers: Mechanisms, interaction and toxicity evaluation

Sulfonamides (SAs) are now recognized as the main emerging environmental pollutants in aquatic environments. Although the bioaccumulation capacities of SAs have been confirmed, the pathway for the penetration of the SAs into lipid bilayer has been not fully understood. In this study, the bioaccumulation mechanism of four typical SAs onto the dipalmitoyl phosphatidylcholine (DPPC) lipid bilayer and their effects on the properties of DPPC bilayer were employed and evaluated respectively by using molecular dynamics simulations. Results show that from the viewpoint of thermodynamics, it is favorable for these SAs partitioning to DPPC bilayer. The accommodation of four SAs onto the lipid membrane needs to undergo several processes, which include the contact stage, transformation stage, and absorption stage. Besides, the sulfamethoxazole (SMX) and sulfamethazine (SMZ) show a strong preference for the DPPC phase rather than the interface region while the sulfadiazine (SDZ) and sulfametoxydiazine (SMD) have similar tendencies in the interface region and DPPC phase. Furthermore, the cytotoxicity of SAs is reflected in their ability to affect the electrostatic potential of the membrane and to reduce the thickness of phospholipid bilayers. This molecular-level study provided an insightful understanding of the toxicity and bioaccumulation of SAs.

Research on advanced methods of electrochemiluminescence detection combined with optical imaging analysis for the detection of sulfonamides

In this study, a novel method that combines electrochemiluminescence (ECL) analysis and digital image processing was developed for the detection of sulfonamides. This method is based on the ECL system of ruthenium terpyridine, with 1 mM tripropylamine as a co-reactant to enhance the performance. Under the optimal conditions comprising a solution of pH 7 and a scanning rate of 0.08 V s^-1, the Pt electrode has an excellent linear detection range from 5 μM to 5 mM, with a detection limit of 0.85 μM (S/N = 3). A wireless camera is used to record the light-emitting process. The recordings are processed, and the digital images are extracted using image-processing algorithms implemented in Python to calculate the brightness value of the image, which has a linear relationship with the logarithm of the sulfonamide concentration. Image analysis simplifies and improves the stability of the ECL analysis process, while also increasing the speed of analysis. The results indicate that the method can successfully detect a sulfonamide concentration of 5 μM. Thus, the analysis method of ECL combined with image processing is feasible for the detection of sulfonamides, thereby displaying its potential applicability as a novel method in drug and food safety, for instance, for sulfonamide detection in antibiotics.

Dual-imprinted mixed matrix membranes for selective recognition and separation: A synergetic imprinting strategy based on complex initiation system

Molecularly imprinted membranes (MIMs) with sufficient and even-distributed recognition sites that can break the permeability-selectivity trade-off phenomenon are desirable in chemical field of selective separation. Herein graphene oxide (GO)/TiO₂-loaded nanocomposite fibrous membranes were prepared by developing two kinds of tetracycline (TC)-imprinted systems in the same MIMs-based material. Thereinto, polydopamine-based and sol-gel-based imprinting processes were applied to the synthesis of GO/TiO₂-loaded dual-imprinted mixed matrix membranes (GT-DIMs). The as-prepared GT-DIMs encompassed innovative GO/TiO₂-based nanocomposite fibrous channels and two kinds of TC-imprinted systems, and critical comparisons regarding the fluxes, rebinding capacities and permselectivity were provided and studied. Importantly, dual-imprinted system of GT-DIMs could not only allow for largely enhanced rebinding result (70.63 mg/g) and fast adsorption equilibrium rate within 30 min, but also facilitate the high permselectivity of TC in complex separation systems and lab-simulated wastewater samples. The permselectivity factors were all around 5.0, which strongly demonstrated the efficiently selective recognition and separation performance of GT-DIMs. Overall, based on testing results of practical separation and scalability, excellent structural stability and separation continuity had been successfully obtained for selective separation applications of pollutants.