Molecular Imprinting: Green Perspectives and Strategies

Novel hydrogel pillar array based ratiometric multicolor fluorescence biosensor for visual detection of alkaline phosphatase activity

Enzyme-induced in-situ fluorescence is crucial for the development of biosensing mechanisms and correlative spectroscopic analysis. Inspired by simple p-aminophenol (AP)-controlled synthesis and the specific catalytic reaction of 4-aminophenyl phosphate (APP) triggered by alkaline phosphatase (ALP), our research proposed a strategy to prepare carbon dots (CDs) as fluorescent signals for ALP detection using AP and 3-aminopropyltrimethoxysilane (APTMS) as the precursors. The further constructed ratiometric fluorescence sensor reduced the detection limit of ALP to 0.075 μU/mL by a significant margin. Considering the need for point-of-care testing (POCT), we chose agarose for the preparation of portable hydrogel sensors so that even untrained personnel can quickly achieve semi-quantitative visual detection of ALP using colorimetric cards. These results demonstrate the practical applicability of ratiometric fluorescence sensing hydrogel pillar arrays, which are important for high-sensitivity, visualization, and portable rapid enzyme activity assays.

A smartphone-combined ratiometric fluorescence molecularly imprinted probe based on biomass-derived carbon dots for determination of tyramine in fermented meat products

A ratiometric fluorescence molecularly imprinted probe employing two distinct emission wavelengths of biomass carbon dots was developed for highly selective and visual quantitative detection of tyramine in fermented meat products. The red emission biomass carbon dots were employed as responsive elements, and the blue ones were utilized as the reference elements. The molecularly imprinted polymers were incorporated in the ratiometric sensing to distinguish and adsorb tyramine. With the linear range of 1-60 μg/L, the ratiometric fluorescence molecularly imprinted probe was successfully applied to detect tyramine in real samples with the satisfactory recoveries of 79.74-112.12% and the detect limitation of 1.3 μg/kg, indicating that this probe has great potential applications for the detection of tyramine in real samples. Moreover, smartphone-based fluorescence signal recognition analysis on hand has been developed for the quantitative analysis of tyramine, providing a portable visual optical analysis terminal for rapid on-site determination of tyramine.

Two-dimensional hydrophilic imprinted resin-graphene oxide composite for selective extraction and rapid determination of gibberellin traces in licorice samples

This study presents novel methodologies and materials for selectively and sensitively determining gibberellin traces in licorice to address food safety concerns. A novel hydrophilic imprinted resin-graphene oxide composite (HMIR-GO) was developed with fast mass transfer, high adsorption capacity, and exceptional aqueous recognition performance for gibberellin. Leveraging the advantages of molecular imprinting, hydrophilic resin synthesis, and rapid mass transfer characteristics of GO, HMIR-GO was employed as an adsorbent, showing resistance to matrix interference. Coupled with HPLC, a rapid and selective method for determining gibberellin was established. Under optimal conditions, the method exhibited a wide linear range (0.02-5.00 μg g-1, r = 0.9999), low detection limits (3.3 ng g-1), and satisfactory recoveries (92.0-98.4%), enabling the accurate and rapid detection of gibberellin in licorice. This study introduces a pioneering strategy for the selective extraction and determination of trace gibberellin levels, offering insights for similar applications in functional foods.

Ratiometric fluorescence sensor based on deep learning for rapid and user-friendly detection of tetracycline antibiotics

The detection of tetracycline antibiotics (TCs) in food holds great significance in minimizing their absorption within the human body. Hence, this study aims to develop a rapid, convenient, real-time, and accurate detection method for detecting antibiotics in an authentic market setting. A colorimetric fluorescence sensor was devised for tetracycline detection utilizing PVA aerogels as the substrate. Its operating principle is based on the IFE effect and antenna effect. A detection device is designed to capture fluorescence images while deep learning was employed to aid in the detection process. The sensor exhibits high responsiveness with a mere 60-s requirement for detection and demonstrates substantial color changes(blue to red), achieving 99% accuracy within the range of 10-100 μM with the assistance of deep learning (Resnet18). Real sample simulation tests yielded recovery rates between 95% and 130%. Overall, the proposed strategy proved to be a simple, portable, reliable, and responsive solution for rapid real-time TCs detection in food samples.

Bio(sensors) based on molecularly imprinted polymers and silica materials used for food safety and biomedical analysis: Recent trends and future prospects

In recent decades, analytical techniques have increasingly focused on the precise quantification. Achieving this goal has been accomplished with conventional analytical approaches that typically require extensive pretreatment methods, significant reagent usage, and expensive instruments. The need for rapid, simple, and highly selective identification platforms has become increasingly pronounced. Molecularly imprinted polymer (MIP) has emerged as a promising avenue for developing advanced sensors that can potentially surpass the limitations of conventional detection methods. In recent years, the application of MIP-silica materials-based sensors has garnered significant attention owing to their distinctive characteristics. These types of probes hold a distinct advantage in their remarkable stability and durability, all of which provide a suitable sensing platform in severe environments. Moreover, the substrate composed of silica materials offers a vast surface area for binding, thereby facilitating the efficient detection of even minuscule concentrations of targets. As a result, sensors based on MIP-silica materials have the potential to be widely applied in various industries, including medical diagnosis, and food safety. In the present review, we have conducted an in-depth analysis of the latest research developments in the field of MIPs-silica materials based sensors, with a focus on succinctly summarizing and elucidating the most crucial findings. This is the first comprehensive review of integration MIPs with silica materials in electrochemical (EC) and optical probes for biomedical analysis and food safety.

Needle trap device technique: From fabrication to sampling

Needle Trap Device (NTD) as a novel, versatile, and eco-friendly technique has played an important role in analytical and environmental chemistry. The distinctive role of this interdisciplinary technique can be defended through the sampling and analysis of biological samples and industrial pollutants in gaseous and liquid environments. In recent years, significant efforts have been made to enhance the performance of the needle trap device resulting in the development of novel extraction routes by various packing materials with improved selectivity and enhanced adsorption characteristics. These achievements can lead to the facilitated pre-concentration of desired analytes. This review tries to have a comparative and comprehensive survey of the three important areas of NTD technique: I) Fabrication and preparation procedures of NTDs; II) Sampling techniques of pollutants using NTDs; and III) Employed materials as adsorbents in NTDs. In the packing-material section, the commercial and synthetic adsorbents such as carbon materials, metal-organic frameworks, aerogel, and polymers are considered. Furthermore, the limitations and potential areas for future development of the NTD technique are presented.

Nitrogen-doped magnetic porous carbon nanospheres derived from dual templates-induced mesoporous polydopamine coated Fe3O4 for efficient extraction and sensitive determination of volatile nitrosamines by gas chromatography-mass spectroscopy

N-nitrosamines (NAs) are highly carcinogenic compounds commonly found in food, beverages, and consumer products. Due to their wide polarity range, it is challenging to find a suitable carbon adsorbent that can simultaneously adsorb and enrich both polar and nonpolar NAs with good recovery. In this study, nitrogen-doped magnetic mesoporous carbon nanospheres (M-MCN) were prepared and employed as an adsorbent for magnetic solid-phase extraction (MSPE) to extract and concentrate four NAs. The introduction of nitrogen functional groups enhanced the hydrophilicity of the carbon material, allowing M-MCN to achieve a balance between hydrophilicity and hydrophobicity, resulting in good recovery for both polar and nonpolar NAs. A method combining MSPE with gas chromatography-mass spectrometry (GC-MS) was developed for the determination of NAs in processed meat and alcoholic beverages. The method exhibited a good linear range (1-100 ng g-1, r2 > 0.9967) and trace-level detection (0.53-6.6 ng g-1). The recovery rates for the four NAs ranged between 85.7 and 110.7 %, with intra-day precision expressed as relative standard deviation (RSD) between 4.1 and 10.7 %, and inter-day precision between 4.8 and 12.9 %. The results demonstrated not only good accuracy and precision but also provided a new adsorbent for the enrichment of trace-level NAs in processed meat and alcoholic beverage samples.

Surface molecularly imprinted polymer/covalent organic framework/silica composite material with specific recognition ability and excellent chromatographic performance

Facing with the difficulty of specific chromatographic separation of nucleoside drugs, this study prepared a surface molecularly imprinted polymer (SMIP) modified covalent organic framework (COF) coated silica stationary phase based on the specificity of molecular imprinting technology and the powerful chromatographic separation performance of COF. This novel SMIP-COF@SiO2 stationary phase can not only specifically identify template molecule and structural analogs, but can also be used to separate multiple types of analytes, such as B vitamins, sulfonamides, alkylbenzenes, phenyl ketones, polycyclic aromatic hydrocarbons and environmental endocrine disruptors, which satisfies the need for complex sample separation. Various retention mechanisms have been investigated and multiple interactions between the SMIP-COF@SiO2 stationary phase and the analytes are discovered. The chromatographic performance of SMIP-COF@SiO2 is far superior to that of the SMIP@SiO2 and COF@SiO2. Furthermore, the SMIP-COF@SiO2 stationary phase can be successfully used to analyze polycyclic aromatic hydrocarbons in the environmental water sample and detect whitening ingredient in skincare product, indicating its great potential for application in various fields.

Solvent and monomer regulation synthesis of core-shelled magnetic β-cyclodextrin microporous organic network for efficient extraction of estrogens in biological samples prior to HPLC analysis

The abnormal estrogens levels in human body can cause many side effects and diseases, but the quantitative detection of the trace estrogens in complex biological samples still remains great challenge. Here we reported the fabrication of a novel core-shell structured magnetic cyclodextrin microporous organic network (Fe3O4@CD-MON) for rapid magnetic solid phase extraction (MSPE) of four estrogens in human serum and urine samples prior to HPLC-UV determination. The uniform spherical core-shell Fe3O4@CD-MONs was successfully regulated by altering the reactive monomers and solvents. The Fe3O4@CD-MONs owned high specific surface area, good hydrophobicity, large superparamagnetism, and abundant extraction sites for estrogens. Under optimal conditions, the proposed MSPE-HPLC-UV method provided wide linearity range (2.0-400 μg L-1), low limits of detection (0.5-1.0 μg L-1), large enrichment factors (183-198), less adsorbent consumption (3 mg), short extraction time (3 min), and good stability and reusability (at least 8 cycles). The established method had also been successfully applied to the enrichment and detection of four estrogens in serum and urine samples with a recovery of 88.4-105.1 % and a relative standard deviation of 1.0-5.9 %. This work confirmed the feasibility of solvent and monomer regulation synthesis of Fe3O4@CD-MON composites, and revealed the great prospects of magnetic CD-MONs for efficient enrichment of trace estrogens in complex biological samples.

Fabrication of molecularly imprinted carbon nanotubes integrating ionic liquids for efficient detection of perfluoroalkyl carboxylic acid in environmental water

It is extremely significant while challenging to accurately detect low-levels of perfluoroalkyl carboxylic acid compounds (PFCAs) in environmental water. Herein, adopting perfluorotetradecanoic acid as the dummy template, selective molecularly imprinted composites (CNTs@ILs@MIPs) grafted carbon nanotubes integrating hydrophilic ionic liquids were successfully prepared via surface imprinting and dummy-template imprinting techniques. The obtained CNTs@ILs@MIPs were applied as selective extraction adsorbent for specifically extract PFCAs in environmental water coupled with gas chromatography-mass spectrometry quantification. Detailed studies were conducted on the main preparation parameters and extraction conditions. The CNTs@ILs@MIPs displayed excellent adsorptivity, and the established method exhibited low LODs (0.60-1.64 ng L-1), wide linearity with R2 above 0.9994, and satisfactory adsorption recoveries (80.5-112.5%) for seven PFCAs. This proposed method provides a new applicable approach for the detection of targeted pollutants in environmental water by utilizing the high affinity and recognition ability of molecularly imprinted carbon nanotube functional materials modified with ionic liquids.

Carbonized polymer dots-based molecular imprinting: An adsorbent with enhanced selectivity for highly efficient recognition and removal of ceftiofur sodium from complex samples

Highly selective removal of residual cephalosporin antibiotics from complex systems is crucial for human health and ecological environment protection. Herein, a newly molecularly imprinted polymer adsorbent (CPDs-NH2@MIP) with enhanced selectivity for ceftiofur sodium (CTFS) was developed by using the special carbonized polymer dots (CPDs-NH2) as functional monomer. The CPDs-NH2 has a nano-spherical structure and functionalized groups (CC, -NH2) via the incomplete carbonization polymerization of citric acid, acrylamide and ethylenediamine, which can accurately interact with CTFS by overcoming steric hindrance, resulting in more precisely imprinted sites and reducing non-imprinted regions in MIP. The presented CPDs-NH2@MIP exhibited excellent adsorption capacity for CTFS (68.62 mg g-1), achieving equilibrium within 10 min, and highly selectivity in mixed solution containing five coexisting substances, with an imprinted factor (5.61). Compared with commercial adsorbents and MIPs prepared with traditional chain functional monomers, the CPDs-NH2@MIP showed significant advantage in selective recognition and separation of target. Analysis of microstructure and mechanism proved that usage of the spherical functional monomer generated precise imprinting sites and dense structure in CPDs-NH2@MIP, which effectively enhanced the selectivity in complex system combined with hydrogen bonding interaction. The idea of designing and using spherical functional monomer will promote the practicality of molecularly imprinted polymer adsorbents.

Precise Capture and Dynamic Release of Circulating Liver Cancer Cells with Dual-Histidine-Based Cell Imprinted Hydrogels

Circulating tumor cells (CTCs) detection presents significant advantages in diagnosing liver cancer due to its noninvasiveness, real-time monitoring, and dynamic tracking. However, the clinical application of CTCs-based diagnosis is largely limited by the challenges of capturing low-abundance CTCs within a complex blood environment while ensuring them alive. Here, an ultrastrong ligand, l-histidine-l-histidine (HH), specifically targeting sialylated glycans on the surface of CTCs, is designed. Furthermore, HH is integrated into a cell-imprinted polymer, constructing a hydrogel with precise CTCs imprinting, high elasticity, satisfactory blood compatibility, and robust anti-interference capacities. These features endow the hydrogel with excellent capture efficiency (>95%) for CTCs in peripheral blood, as well as the ability to release CTCs controllably and alive. Clinical tests substantiate the accurate differentiation between liver cancer, cirrhosis, and healthy groups using this method. The remarkable diagnostic accuracy (94%), lossless release of CTCs, material reversibility, and cost-effectiveness ($6.68 per sample) make the HH-based hydrogel a potentially revolutionary technology for liver cancer diagnosis and single-cell analysis.

Fabrication of fluorescence probe based on molecularly imprinted polymers on red emissive biomass-derived carbon dots coupled with smartphone readout for tyramine determination in fermented meat products

A fluorescence probe based on molecularly imprinted polymers on red emissive biomass-derived carbon dots (r-BCDs@MIPs) was developed to detect tyramine in fermented meat products. The red emissive biomass-derived carbon dots (r-BCDs) were synthesized by the one-step solvothermal method using discarded passion fruit shells as raw materials. The fluorescence emission peak of r-BCDs was at 670 nm, and the relative quantum yield (QY) was about 2.44%. Molecularly imprinted sensing materials were prepared with r-BCDs as fluorescent centers for the detection of trace tyramine, which showed a good linear response in the concentration range of tyramine from 1 to 40 µg L-1. The linear correlation coefficient was 0.9837, and the limit of detection was 0.77 µg L-1. The method was successfully applied to the determination of tyramine in fermented meat products, and the recovery was 87.17-106.02%. The reliability of the results was verified through high-performance liquid chromatography (HPLC). Furthermore, we combined the r-BCDs@MIPs with smartphone-assisted signal readout to achieve real-time detection of tyramine in real samples. Considering its simplicity and convenience, the method could be used as a rapid and low-cost promising platform with broad application prospects for on-site detection of trace tyramine with smartphone-assisted signal readout.

Development of a selective electrochemical microsensor based on molecularly imprinted polydopamine/ZIF-67/laser-induced graphene for point-of-care determination of 3-nitrotyrosine

3-nitrotyrosine (3-NT) is a biomarker closely associated with the early diagnosis of oxidative stress-related disorders. The development of an accurate, cost-effective, point-of-care 3-NT sensor holds significant importance for self-monitoring and clinical treatment. In this study, a selective, sensitive, and portable molecularly imprinted electrochemical sensor was developed. ZIF-67 with strong adsorption capacity was facilely modified on an electrochemically active laser-induced graphene (LIG) substrate (formed ZIF-67/LIG). Subsequently, biocompatible dopamine was chosen as the functional monomer, and interference-free ʟ-tyrosine was used as the dummy template to create molecularly imprinted polydopamine (MIPDA) on the ZIF-67/LIG, endowing the sensor with selectivity. The morphologies, electrochemical properties, and detection performance of the sensor were comprehensively investigated using scanning electron microscopy, cyclic voltammetry, electrochemical impedance spectroscopy, and differential pulse voltammetry. To achieve the best performance, several parameters were optimized, including the number of polymerization cycles (15), elution time (60 min), incubation time (7 min), and pH of the buffer solution (6). The turnaround time for this sensor is 10 min. Benefiting from the alliance of MIPDA, ZIF-67, and LIG, the sensor exhibited excellent sensitivity with a detection limit of 6.71 nM, and distinguished selectivity against 11 interfering substances. To enable convenient clinical diagnosis, a customized electrochemical microsensor with MIPDA/ZIF-67/LIG was designed, showcasing excellent reliability and convenience in detecting biological samples without pretreatment. The proposed microsensor will not only facilitate clinical diagnosis and improve patient care, but also provide inspiration for the development of other portable and accurate electrochemical biosensors.

Ratio-fluorescence detection of tert-butylhydroquinone based on non-conjugated polymer dots and gold nanoclusters

A novel ratiometric fluorescent probe based on non-conjugated polymer dots (NCPDs) and gold nanocluster (AuNCs) was constructed to determine tert-butylhydroquinone (TBHQ). The probe exhibited dual emission peaks at 480 nm and 630 nm under 370 nm excitation. The fluorescence of AuNCs was quenched by TBHQ due to strong electrostatic interactions, whereas the emission of NCPDs increased. The ratio of fluorescence intensity at 480 nm to 630 nm (F480 / F630) was monitored as analytical signal response. The probe have been utilized for the detection of TBHQ with good linear relationship in the range of 0.2 to 60 μg/mL. The limit of detection (LOD) and the limit of quantitation (LOQ) were 0.048 μg/mL and 0.159 μg/L, respectively. Three levels of spiked-in TBHQ concentrations were obtained with recovery rates from 80 % to 102 %. The present study provided an effective ratiometric fluorescence method for selective screening of TBHQ in food samples.

A sharp and selective fluorescence paper-based sensor based on inner filter effect for ratiometric detection of four Sudan dyes in food matrix

The addition of Sudan dyes with carcinogenic effects to food threatens human health. Herein, a ratiometric fluorescence strip consisting of core-shell upconversion particles (NaYF4:Yb,Tm@NaYF4:Yb,Er), metal-organic frameworks and dual-template molecularly imprinted polymers was developed to selectively and sensitively detect four Sudan dyes based on inner filter effect (detection time only takes 8 min). The high adsorption capacity of metal-organic frameworks and the greater overlap between the emission of NaYF4:Yb,Tm@NaYF4:Yb,Er and the absorbance of four Sudan dyes enable the signal responses to be more sensitive. The limits of detection in chilli powder samples are as low as 29.87 ng/g, 37.55 ng/g, 47.89 ng/g and 51.02 ng/g, with satisfactory recovery (93.32-103.4%) and minor relative standard deviations (≤4.3%). This method broadens the idea for low-cost and portable detection of multiple illegal additives in complex substrates with high selectivity and sensitivity based on one kind of fluorescent strip.

A ratiometric fluorescence and colorimetry dual-signal sensing strategy based on o-phenylenediamine and AuNCs for determination of Cu2+ and glyphosate

A ratiometric fluorescence sensing strategy has been developed for the determination of Cu2+ and glyphosate with high sensitivity and specificity based on OPD (o-phenylenediamine) and glutathione-stabilized gold nanoclusters (GSH-AuNCs). Water-soluble 1.75-nm size GSH-AuNCs with strong red fluorescence and maximum emission wavelength at 682 nm were synthesized using GSH as the template. OPD was oxidized by Cu2+, which produced the bright yellow fluorescence oxidation product 2,3-diaminophenazine (DAP) with a maximum fluorescence emission peak at 570 nm. When glyphosate existed in the system, the chelation between glyphosate and Cu2+ hindered the formation of DAP and reduced the fluorescence intensity of the system at the wavelength of 570 nm. Meanwhile, the fluorescence intensity at the wavelength of 682 nm remained basically stable. It exhibited a good linear relationship towards Cu2+ and glyphosate in water in the range 1.0-10 µM and 0.050-3.0 µg/mL with a detection limit of 0.547 µM and 0.0028 µg/mL, respectively. The method was also used for the semi-quantitative determination of Cu2+ and glyphosate in water by fluorescence color changes visually detected by the naked eyes in the range 1.0-10 µM and 0.30-3.0 µg/mL, respectively. The sensing strategy showed higher sensitivity, more obvious color changes, and better disturbance performance, satisfying with the detection demands of Cu2+ and glyphosate in environmental water samples. The study provides a reliable detection strategy in the environment safety fields.

Preparation of dual-functional epitope imprinted polymers for the enrichment of transferrin

Transferrin (TRF), a glycoprotein involved in cellular iron uptake, is a potential target for the diagnosis and treatment of several diseases and cancers. Therefore, the identification and isolation of TRF is clinically important. In this work, we prepared magnetic molecularly imprinted polymers (EMIP) based on metal chelation using norepinephrine and 3-aminophenylboronic acid as functional monomers. The obtained EMIP shows excellent recognition of TRF with the adsorption capacity of 94.2 mg/g and imprinting factor of 3.50. In addition, EMIP was characterized by high specificity, good adsorption performance and stability, and was successfully used for the analysis of TRF in human serum. The present study provides a reliable scheme for targeted epitope imprinting of polymers with metal chelating and dual-functional monomers, showing great potential for biosample analysis.

Renin imprinted Poly(methyldopa) for biomarker detection and disease therapy

Conventional molecularly imprinted polymers (MIPs) perform their functions principally depended on their three dimensional (3D) imprinted cavities (recognition sites) of templates. Here, retaining the function of recognition sites resulted from the imprinting of template molecules, the role of functional monomers is explored and expanded. Briefly, a class of dual-functional renin imprinted poly(methyldopa) (RMIP) is prepared, consisting of a drug-type function monomer (methyldopa, clinical high blood pressure drug) and a corresponding disease biomarker (renin, biomarker for high blood pressure disease). To boost target-to-receptor binding ratio and sensitivity, the microstructure of recognition sites is beforehand calculated and designed by Density Functional Theory calculations, and the whole interfacial structure, property and thickness of RMIP film is regulated by adjusting the polymerization techniques. The dual-functional applications of RMIP for biomarker detection and disease therapy in vivo is explored. Such RMIP-based biosensors achieves highly sensitive biomarker detection, where the LODs reaches down to 1.31 × 10-6 and 1.26 × 10-6 ng mL-1 for electrochemical and chemical polymers, respectively, and the application for disease therapy in vivo has been verified where displays the obviously decreased blood pressure values of mice. No acute and long-term toxicity is found from the pathological slices, declaring the promising clinical application potential of such engineered RMIP nanostructure.

A competitive-type photoelectrochemical aptasensor for 17 beta-estradiol detection in microfluidic devices based on a novel Au@Cd:SnO2/SnS2 nanocomposite

A competitive-type photoelectrochemical (PEC) aptasensor coupled with a novel Au@Cd:SnO2/SnS2 nanocomposite was designed for the detection of 17β-estradiol (E2) in microfluidic devices. The designed Au@Cd:SnO2/SnS2 nanocomposites exhibit high photoelectrochemical activity owing to the good matching of cascade band-edge and the efficient separation of photo-generated e-/h+ pairs derived from the Cd-doped defects in the energy level. The Au@Cd:SnO2/SnS2 nanocomposites were loaded into carbon paste electrodes (CPEs) to immobilize complementary DNA (cDNA) and estradiol aptamer probe DNA (E2-Apt), forming a double-strand DNA structure on the CPE surface. As the target E2 interacts with the double-strand DNA, E2-Apt is sensitively released from the CPE, subsequently increasing the photocurrent intensity due to the reduced steric hindrance of the electrode surface. The competitive-type sensing mechanism, combined with high PEC activity of the Au@Cd:SnO2/SnS2 nanocomposites, contributed to the rapid and sensitive detection of E2 in a "signal on" manner. Under the optimized conditions, the PEC aptasensor exhibited a linear range from 1.0 × 10-13 mol L-1 to 3.2 × 10-6 mol L-1 and a detection limit of 1.2 × 10-14 mol L-1 (S/N = 3). Moreover, the integration of microfluidic device with smartphone controlled portable electrochemical workstation enables the on-site detection of E2. The small sample volume (10 µL) and short analysis time (40 min) demonstrated the great potential of this strategy for E2 detection in rat serum and river water. With these advantages, the PEC aptasensor can be utilized for point-of-care testing (POCT) in both clinical and environmental applications.

Fabricating Ultrathin Imprinting Layer for Fast Capture of Valsartan via a Metal Affinity-Oriented Surface Imprinting Method

Rapid separation and enrichment of targets in biological matrixes are of significant interest in multiple life sciences disciplines. Molecularly imprinted polymers (MIPs) have vital applications in extraction and sample cleanup owing to their excellent specificity and selectivity. However, the low mass transfer rate, caused by the heterogeneity of imprinted cavities in polymer networks and strong driving forces, significantly limits its application in high-throughput analysis. Herein, one novel metal affinity-oriented surface imprinting method was proposed to fabricate an MIP with an ultrathin imprinting layer. MIPs were prepared by immobilized template molecules on magnetic nanoparticles (NPs) with metal ions as bridges via coordination, and then polymerization was done. Under the optimized conditions, the thickness of the imprinting layer was merely 1 nm, and the adsorption toward VAL well matched the Langmuir model. Moreover, it took just 5 min to achieve adsorption equilibrium significantly faster than other reported MIPs toward VAL. Adsorption capacity still can reach 25.3 mg/g ascribed to the high imprinting efficiency of the method (the imprinting factor was as high as 5). All evidence proved that recognition sites were all external cavities and were evenly distributed on the surface of the NPs. The obtained MIP NPs exhibited excellent selectivity and specificity toward VAL, with good dispersibility and stability. Coupled with high-performance liquid chromatography, it was successfully used as a dispersed solid phase extraction material to determine VAL in serum. Average recoveries are over 90.0% with relative standard deviations less than 2.14% at three spiked levels (n = 3). All evidence testified that the MIPs fabricated with the proposed method showed a fast trans mass rate and a large rebinding capacity. The method can potentially use high-throughput separation and enrichment of target molecules in batch samples to meet practical applications.

Portable tri-color ratiometric fluorescence paper sensor for intelligent visual detection of dual-antibiotics and aluminium ion

The toxicological effect between co-existed antibiotics and metal ions was dangerous to the ecological environment and public health. However, the rapid quantification tools with convenience, accuracy and low cost for the detection of multiple targets were still challenging. Herein, a portable tri-color ratiometric fluorescence paper sensor was constructed by coupling of blue carbon dots and fluorescence imprinted polymer for down/up conversion simultaneous detection of tetracycline and sulfamethazine. Interestingly, the cascade detection of aluminum ion was also realized based on the individual detection system of tetracycline without the assistance of complex coupling reagents. The detection limits of smartphone method for the visual detection of tetracycline, sulfamethazine and aluminum ion were calculated as 0.014 μM, 0.004 μM and 0.019 μM, respectively. The portable fluorescence paper sensor was applied for the visual detection of tetracycline, sulfamethazine and aluminum ion in actual samples successfully with satisfactory recoveries. With the advantages of rapidness, low cost, and portability, the developed portable fluorescence paper sensor provided a new strategy for the visual real-time detection of multiple targets.

Hydrophilic molecularly imprinted lysozyme-BiOBr composite with enhanced visible light utilization for selective removal of trace contaminants in water

The development of high-efficiency molecularly imprinted photocatalysts is still challenging due to the lack of hydrophilic and suitable functional monomers. In this work, the bio-sourced lysozyme was developed as the hydrophilic functional monomer, and Cu-doped BiOBr was used as the photocatalysts, to prepare a novel hydrophilic molecularly imprinted lysozyme-BiOBr composite (BiOBr-Cu/LyzMIP) with enhanced visible light utilization. Lysozyme could form a transparent layer to mitigate the light transmission obstruction caused by the surface imprinting layer, making it an ideal functional monomer. The prepared BiOBr-Cu/LyzMIP possessed red-shifted visible-light absorption edge and minor reduction of light absorbance, indicating the enhanced utilization of visible light. Accordingly, BiOBr-Cu/LyzMIP demonstrated excellent degradation rate (99.4 % in 20 min), exceptional degradation efficiency (0.211 min-1), and superior reusability. Moreover, BiOBr-Cu/LyzMIP exhibited rapid adsorption equilibrium (20 min), good imprinting factor (2.67), and favourable degradation selectivity (>1.75), indicating the good imprinting effect resulting from abundant functional groups of lysozyme. Versatility experiments on different templates suggested that the proposed approach allowed flexibility in selecting a wide range of hazardous contaminants according to practical requirements. The present work expands the application of lysozyme-based composites in the environmental field, and provides a new one-stop pathway for efficient and sustainable treatment of contaminated water.

Biomass waste-derived magnetic material coated with dual-dummy-template molecularly imprinted polymer for simultaneous extraction of organophosphorus and carbamate pesticides

An eco-friendly biomass waste-derived magnetic material coated with a dual-dummy-template molecularly imprinted polymer was fabricated using aqueous ethanol as a green porogen, lower amounts of toxic compounds as template molecules, and tyrosine and tryptophan as biocompatible binary monomers. The binding characteristics and selectivity of the material toward pesticides were assessed. High adsorption capacities ranging from 150.11 to 509.09 mg g-1 and imprinting factors reaching 2.2 were achieved within just 30 s. The material was applied for extraction of organophosphorus and carbamate pesticides prior to HPLC analysis. Under the optimum conditions, low limits of detection and quantitation were achieved, with ranges of 0.05-1.49 μg/L and 0.18-5.00 μg/L, respectively. The established approach enables efficient analysis of vegetable and fruit samples, yielding satisfactory recoveries ranging between 80 and 110 %. The method showed promise as an analytical method for the sensitive enrichment of pesticide residues in vegetable and fruit samples.

A Simple, Sensitive, and Greener HPLC-DAD Method for the Simultaneous Analysis of Two Novel Orexin Receptor Antagonists

The orexin receptor antagonist (ORA) is one of the new psychopharmacological agents used in the treatment of insomnia. There are currently no documented greener high-performance liquid chromatography-diode array detector (HPLC-DAD) methods for the analysis of ORA antagonists, lemborexant (LMB) and suvorexant (SUV) simultaneously. Therefore, in this study, a simple, sensitive, and greener HPLC-DAD method has been developed for the simultaneous quantitative analysis of LMB and SUV in bulk and laboratory-prepared mixture. The developed method was validated for numerous validation parameters and evaluated for greenness. The C18 Waters Spherisorb CN (4.6 × 250 mm2; 5 μm) column was used for the chromatographic separation. The mobile phase composition was ethanol: 10 mM KH2PO4 buffer in a ratio of (60:40 v/v). The DAD detection was performed at 253 nm using a Waters DAD detector. The greenness was evaluated using the analytical Eco-Scale (AES), ChlorTox, and analytical GREEnness (AGREE) techniques. The calibration curves showed excellent linearity for LMB and SUV between the concentration range of 125-5000 ng/mL and 250-10,000 ng/mL, respectively. In addition, the proposed HPLC-DAD method was accurate, precise, robust, highly sensitive, and greener. AES, ChlorTox, and AGREE scales were predicted by the HPLC-DAD method to be 91, 1.14 g, and 0.79, respectively, showing an excellent greenness profile. The greener HPLC-DAD method was successfully used to analyze both medicines quantitatively in bulk and laboratory-prepared synthetic mixtures. The findings of this study indicated that the proposed HPLC-DAD method may be consistently applied to evaluate LMB and SUV in bulk and dosage forms.

Sustainable carbon dots from Borreria hispida: enhanced colorimetric sensing of Fe3+ ions and biological applications in live cell imaging

This study presents the synthesis of advanced nanomaterials derived from the hedge-grown herbal plant, Borreria hispida, and explores their environmental and biological applications. Using a one-step hydrothermal synthesis method, carbon dots derived from Borreria hispida (BHCD) were fabricated and thoroughly characterized through XRD, TEM, FTIR, CHNS, UV-visible, and PL spectroscopy analyses. Under UV illumination, these plant-based carbon dots demonstrated exceptional water solubility, notable photo stability, and a high quantum yield of 40.8%. The average particle size of BHCD was absorbed around 0.5 to 3.5 nm, contributing to superior selectivity and sensitivity in detecting Fe3+ ions, with a limit of detection of 1.2 × 10-6 M. Investigation into the sensing mechanism revealed a binding model wherein two carbon atom molecules bind to one Fe3+ atom in a 2 : 1 ratio for BHCDs and Fe3+ interactions. Additionally, the effectiveness of the developed fluorescent probe for Fe3+ detection was validated using real water samples from ponds and lakes, highlighting its potential for environmental monitoring applications. Furthermore, the biological effects of BHCD were evaluated through cytotoxic assays, demonstrating significant inhibitory effects on MCF7 breast cancer cell lines, with a maximum cell viability of 60%. This research underscores the multifaceted potential of BHCD in environmental monitoring and biomedical applications.

Molecularly imprinted polymers and porous organic frameworks based analytical methods for disinfection by-products in water and wastewater

Disinfection by-products (DBPs) with heritage toxicity, mutagenicity and carcinogenicity are one kind of important new pollutants, and their detection and removal in water and wastewater has become a common challenge facing mankind. Advanced functional materials with ideal selectivity, adsorption capacity and regeneration capacity provide hope for the determination of DBPs with low concentration levels and inherent molecular structural similarity. Among them, molecularly imprinted polymers (MIPs) are favored, owing to their predictable structure, specific recognition and wide applicability. Also, metal-organic frameworks (MOFs) and covalent-organic frameworks (COFs) with unique pore structure, large specific surface area and easy functionalization, attract increasing interest. Herein, we review recent advances in analytical methods based on the above-mentioned three functional materials for DBPs in water and wastewater. Firstly, MIPs, MOFs and COFs are briefly introduced. Secondly, MIPs, MOFs and COFs as extractants, recognition element and adsorbents, are comprehensively discussed. Combining the latest research progress of solid-phase extraction (SPE), sensor, adsorption and nanofiltration, typical examples on MIPs and MOFs/COFs based analytical and removal applications in water and wastewater are summarized. Finally, the application prospects and challenges of the three functional materials in DBPs analysis are proposed to promote the development of corresponding analytical methods.

Unlocking New Avenues: Solid-State Synthesis of Molecularly Imprinted Polymers

Molecularly imprinted polymers (MIPs) are established artificial molecular recognition platforms with tailored selectivity towards a target molecule, whose synthesis and functionality are highly influenced by the nature of the solvent employed in their synthesis. Steps towards the "greenification" of molecular imprinting technology (MIT) has already been initiated by the elaboration of green MIT principles; developing MIPs in a solvent-free environment may not only offer an eco-friendly alternative, but could also significantly influence the affinity and expected selectivity of the resulting binding sites. In the current study the first solvent-free mechanochemical synthesis of MIPs via liquid-assisted grinding (LAG) is reported. The successful synthesis of the imprinted polymer was functionally demonstrated by measuring its template rebinding capacity and the selectivity of the molecular recognition process in comparison with the ones obtained by the conventional, non-covalent molecular imprinting process in liquid media. The results demonstrated similar binding capacities towards the template molecule and superior chemoselectivity compared to the solution-based MIP synthesis method. The adoption of green chemistry principles with all their inherent advantages in the synthesis of MIPs may not only be able to alleviate the potential environmental and health concerns associated with their analytical (e.g., selective adsorbents) and biomedical (e.g., drug carriers or reservoirs) applications, but might also offer a conceptual change in molecular imprinting technology.

Separation and Detection of Catechins and Epicatechins in Shanxi Aged Vinegar Using Solid-Phase Extraction and Hydrophobic Deep Eutectic Solvents Combined with HPLC

This research presents a new, eco-friendly, and swift method combining solid-phase extraction and hydrophobic deep eutectic solvents (DES) with high-performance liquid chromatography (SPE-DES-HPLC) for extracting and quantifying catechin and epicatechin in Shanxi aged vinegar (SAV). The parameters, such as the elution solvent type, the XAD-2 macroporous resin dosage, the DES ratio, the DES volume, the adsorption time, and the desorption time, were optimized via a one-way experiment. A central composite design using the Box-Behnken methodology was employed to investigate the effects of various factors, including 17 experimental runs and the construction of three-dimensional response surface plots to identify the optimal conditions. The results show that the optimal conditions were an HDES (tetraethylammonium chloride and octanoic acid) ratio of 1:3, an XAD-2 macroporous resin dosage of 188 mg, and an adsorption time of 11 min. Under these optimal conditions, the coefficients of determination of the method were greater than or equal to 0.9917, the precision was less than 5%, and the recoveries ranged from 98.8% to 118.8%. The environmentally friendly nature of the analytical process and sample preparation was assessed via the Analytical Eco-Scale and AGREE, demonstrating that this method is a practical and eco-friendly alternative to conventional determination techniques. In summary, this innovative approach offers a solid foundation for the assessment of flavanol compounds present in SAV samples.

Combination of online hollow fiber liquid phase microextraction with smartphone-based sensing for in situ formaldehyde assay in fabric and wastewater samples

A miniaturized analytical methodology was introduced based on the combination of a direct and online hollow fiber microextraction method with smartphone color detection. The method was used for the determination of formaldehyde (target analyte) in fabric and wastewater samples. In this regard, two reagents including ammonium acetate buffer and acetylacetone were added to the formaldehyde samples to create a colored compound. The colored compound was extracted from the sample by using the hollow fiber liquid-phase microextraction method, the extracted phase was not taken out of the extraction box and was directly transferred into a specially designed detection cell, and a smartphone was applied for in-situ color sensing and data readout. This combination gathered the advantages of both state-of-the-art microextraction techniques and smartphone sensing. Formaldehyde, as a carcinogenic compound widely used in paint and clothing industries, was selected as a model test. Factors affecting extraction efficiency were investigated and optimized, including the type of organic solvents, reagent concentration, salt, pH, stirring speed, reaction temperature, and extraction time. The linear region of the method under optimal conditions was 40-1500 µg L-1 for wastewater samples and 0.3-11.2 mg kg-1 for fabrics. The limit of detection and limit of qualification were 13 and 40 µg L-1, respectively. The relative standard deviations for concentrations of 100 and 1000 µg L-1 were 6% and 4%, respectively. To evaluate the application of the method for real samples, types of fabric and two samples of oil refinery wastewater were selected. The relative recovery in real samples was 84-98%. The results of the analytical parameters of the method show that the developed method can be used as an efficient method to determine formaldehyde in real samples.

Four birds with one stone: Aggregation-induced emission-type zeolitic imidazolate framework-8 based bionic nanoreactor for portable detection of olaquindox in environmental water and swine urine by smartphone

The abuse of olaquindox (OLA) as both an antimicrobial agent and a growth promoter poses significant threats to the environment and human health. While nanoreactors have proven effective in hazard detection, their widespread adoption has been hindered by tedious chemical processes and limited functionality. In this study, we introduce a novel green self-assembly strategy utilizing invertase, horseradish peroxidase, antibodies, and gold nanoclusters to form an aggregation-induced emission-type zeolitic imidazolate framework-8 nanoreactor. The results demonstrate that the lateral flow immunoassay not only allows for qualitative naked eye detection but also enables optical analysis through the fluorescence generated by aggregated gold nanoclusters and enzyme-catalyzed enhancement of visible colorimetric signals. To accommodate more detection scenarios, the photothermal effects and redox reactions of the nanoreactor can fulfill the requirements of thermal sensing and electrochemical analysis for smartphone applications. Remarkably, the proposed approach achieves a detection limit 17 times lower than conventional methods. Besides, the maximum linear range spans from 0.25 to 5 μg/L with high specificity, and the recovery is 85.2-112.9% in environmental water and swine urine. The application of this high-performance nanoreactor opens up avenues for the construction of multifunctional biosensors with great potential in monitoring hazardous materials.

A sensitive fluorometric-colorimetric dual-mode intelligent sensing platform for the detection of formaldehyde

Excess formaldehyde (FA) is a strong carcinogen, so the development of a rapid visualized and portable formaldehyde detection platform is of great research importance. A multi-color fluorescence sensing system constituted of model compound (NAHN) and red-emitting InP/ZnS QDs was constructed herein, which can simultaneously realize fluorometric-colorimetric dual-mode sensing when exposed to FA environment. Its preparation process was simplified, the detection process was green, and the limits of detection (LOD) were 0.623 μM and 0.791 μM, respectively. The high recoveries of FA in actual water samples indicated that the sensor had broad application prospects. The prepared fluorescent film can be utilized for rapid visual simulation analysis of FA on the surface of various fruits and vegetables. In addition, a serial logic gate was designed to quickly semi-quantitatively assess FA concentration, which promoted the realization of on-site intelligent evaluation of FA.

Lanthanide metal-organic framework-based surface molecularly imprinted polymers ratiometric fluorescence probe for visual detection of perfluorooctanoic acid with a smartphone-assisted portable device

Perfluorooctanoic acid (PFOA) poses a threat to the environment and human health due to its persistence, bioaccumulation, and reproductive toxicity. Herein, a lanthanide metal-organic framework (Ln-MOF)-based surface molecularly imprinted polymers (SMIPs) ratiometric fluorescence probe (Eu/Tb-MOF@MIPs) and a smartphone-assisted portable device were developed for the detection of PFOA with high selectivity in real water samples. The integration of Eu/Tb MOFs as carriers not only had highly stable multiple emission signals but also prevented deformation of the imprinting cavity of MIPs. Meanwhile, the MIPs layer preserved the fluorescence of Ln-MOF and provided selective cavities for improved specificity. Molecular dynamics (MD) was employed to simulate the polymerization process of MIPs, revealing that the formation of multiple recognition sites was attributed to the establishment of hydrogen bonds between functional monomers and templates. The probe showed a good linear relationship with PFOA concentration in the range of 0.02-2.8 μM, by giving the limit of detection (LOD) of 0.98 nM. Additionally, The red-green-blue (RGB) values analysis based on the smartphone-assisted portable device demonstrated a linear relationship of 0.1-2.8 μM PFOA with the LOD of 3.26 nM. The developed probe and portable device sensing platform exhibit substantial potential for on-site detecting PFOA in practical applications and provide a reliable strategy for the intelligent identification of important targets in water environmental samples.

Application of a novel deep eutectic solvent modified carbon nanotube for pipette-tip micro solid phase extraction of 6-mercaptopurine

BACKGROUND

6-mercaptopurine (6-MP) is a chemotherapy drug mainly used to treat leukemia. It is a persistent organic pollutant and can remain in the environment for a long period of time. The presence of 6-MP in the environment poses a number of hazards and needs to be assessed to monitor its potential risk to human health and the environment. However, due to its trace amount in complicated matrices, a clean-up and preconcentration step before its determination is compulsory.

RESULTS

As a highly efficient adsorbent for the extrication of 6-mercaptopurine (6-MP), a novel carbon nanotube doped with camphor: decanoic acid deep eutectic solvent was synthesized and applied as a packing material for the pipette-tip micro solid phase extraction sorbent of 6-MP from tap, wastewater and seawater samples before its spectrophotometric determination. Characteristics and structure of this adsorbent was fully investigated. Factors affecting extraction, including type and volume of the eluent, ionic strength and pH of the sample solution, amount of adsorbent, and number of extraction and elution cycles were optimized using one-factor-at-a-time and response surface methodologies. The method was found to be linear in the range of 1 to 1000 µg/L with a limit of detection and quantification of 0.2 and 0.7 µg/L, respectively. Reproducibility as relative standard deviation was better than 4.6%.

CONCLUSION

Application of deep eutectic solvent modified carbon nanotube indicated suitable microextraction results and good potential for rapid extraction of trace amounts of 6-MP from different aqueous samples. The amount of sample required for the analysis was less than 10 mL and only 1.5 mg of the adsorbent was used. The total analysis time, including extraction was less than 15 min and the adsorbent could be used for at least 10 times, without significantly losing its adsorption ability. Compared to using unmodified usual carbon nanotubes, deep eutectic solvent doped carbon nanotubes showed 19.8% higher extraction ability.

Molecular Imprinting-Based SERS Detection Strategy for the Large-Size Protein Quantitation and Curbing Non-Specific Recognition

Molecular imprinting-based surface-enhanced Raman scattering (MI-SERS) sensors have shown remarkable potential from an academic standpoint. However, their practical applications, especially in the detection of large-size protein (≥10 nm), face challenges due to the lack of versatile sensing strategies and nonspecific fouling of matrix species. Herein, we propose a Raman reporter inspector mechanism (RRIM) implemented on a protein-imprinted polydopamine (PDA) layer coated on the SERS active substrate. In the RRIM, after large-size protein recognition, the permeability of the PDA imprinted cavities undergoes changes that are scrutinized by Raman reporter molecules. Target proteins can specifically bind and fully occupy the imprinted cavities, whereas matrix species cannot. Then, Raman reporter molecules with suitable size are introduced to serve as both inspectors of the recognition status and inducers of the SERS signal, which can only penetrate through the vacant and nonspecifically filled cavities. Consequently, changes in the SERS signal exclusively originate from the specific binding of target proteins, while the nonspecific recognition of matrix species is curbed. The RRIM enables reproducible quantitation of the large-size cyanobacteria-specific protein model (≥10 nm), phycocyanin, at the level down to 2.6 × 10-3 μg L-1. Finally, the practical applicability of the RRIM is confirmed by accurately analyzing crude urban waterway samples over 21 min without any pretreatment.

Graphene quantum dots on TiO2 nanotubes as a light-assisted peroxidase nanozyme

Hybrid nanozyme graphene quantum dots (GQDs) deposited TiO2 nanotubes (NTs) on titanium foil (Ti/TiO2 NTs-GQDs) were manufactured by bestowing the hybrid with the advantageous porous morphology, surface valence states, high surface area, and copious active sites. The peroxidase-like activity was investigated through the catalytic oxidation of chromogenic substrate 3,3',5,5'-tetramethylbenzidine (TMB) in the presence of H2O2, which can be visualized by the eyes. TiO2 NTs and GQDs comprising oxygen-containing functional groups can oxidize TMB in the presence of H2O2 by mimicking peroxidase enzymes. The peroxidase-mimicking activity of hybrid nanozyme was significantly escalated by introducing light illumination due to the photosensitive features of the hybrid material. The peroxidase-like activity of Ti/TiO2 NTs-GQDs enabled H2O2 determination over the linear range of 7 to 250 μM, with a LOD of 2.1 µM. The satisfying peroxidase activity is possibly due to the unimpeded access of H2O2 to the catalyst's active sites. The porous morphology provides the easy channeling of reactants and products. The periodic structure of the material also gave rise to acceptable reproducibility. Without material functionalization, the Ti/TiO2 NTs-GQDs can be a promising substitute for peroxidases for H2O2 detection.

A ratiometric fluorescence imprinted sensor based on N-CDs and metal-organic frameworks for visual smart detection of malathion

Sensitive and rapid detection of pesticide residues in food is essential for human safety. A ratiometric imprinted fluorescence sensor N-CDs@Eu-MOF@MIP (BR@MIP) was constructed to sensitively detect malathion (Mal). Europium-based metal organic frameworks (Eu-MOF) were used as supporters to improve the sensitivity of the BR@MIP. N-doped carbon dots (N-CDs) were used as fluorescent source to produce fluorescent signal. A linear relationship between the concentration of Mal and the fluorescence response of the sensor was found in the Mal concentration range of 1-10 μM with a limit of detection (LOD) of 0.05 μM. Furthermore, the sensor was successfully applied for the detection of Mal in lettuce, tap water, and soil samples, with recoveries in the range of 93.0 % - 99.3 %. Additionally, smartphone-based sensors were used to detect Mal in simulated real samples. Thus, the construction of ratiometric imprinted fluorescence sensor has provided a good strategy for the detection of Mal.

Enhanced molecular recognition with longer chain crosslinkers in molecularly imprinted polymers for an efficient separation of TR active substances

Molecular imprinting technology has been widely studied as a technique to obtain molecular recognition by artificial means. Selecting functional monomers or polymerization conditions plays a key role to optimize molecularly imprinted polymer (MIP) synthesis. To date, there have been few reports well exploiting the effect of crosslinkers. Here, in this study, we synthesized the MIPs using poly(ethyleneglycol) dimethacrylate with different units of ethylene oxide (n = 1 to 23) as crosslinkers to observe the molecular recognition abilities. The MIPs were attached to the surface of mono-dispersed polymer beads. The obtained spherical MIPs and non-imprinted polymers were filled in a column for high performance liquid chromatography. Then the retention selectivity toward TR active substances was evaluated. The result revealed that the recognition ability did not improve regardless of the amount of ethylene oxide. With the crosslinker (n = 9), extremely high retention selectivity was observed, which provides at most around ten times as large imprinting factors in comparison with other MIPs. Interestingly, we obtained the highest recognition ability at around polymerization temperature from the evaluation of the recognition ability toward temperature shift using the MIP (n = 9). In general, hydrogen bonding based on MIPs provides high recognition ability at low temperature, whereas, this study indicates that the use of flexible crosslinkers may enable the synthesis of MIPs that precisely memorize the conditions of polymerization. Lastly, we simultaneously analyzed the TR active substances using the column filled with MIPs (n = 9). The result showed relatively linear correlation between the retention strength of each substance and phycological activity toward TR obtained by yeast assay. Therefore, we can conclude that an induced fit like the receptor emerged by constructing the flexible molecular recognition field.

Tailor-made molecular imprints for biological event intervention

Molecular imprints, which are crosslinked architectures containing specific molecular recognition cavities for targeting compounds, have recently transitioned from in vitro diagnosis to in vivo treatment. In current application scenarios, it has become an important topic to create new biomolecular recognition pathways through molecular imprinting, thereby inhibiting the pathogenesis and regulating the development of diseases. This review starts with a pathological analysis, mainly focusing on the corresponding artificial enzymes, enzyme inhibitors and antibody mimics with enhanced functions that are created by molecular imprinting strategies. Recent advances are highlighted in the use of molecular imprints as tailor-made nanomedicines for the prevention of three major diseases: metabolic syndrome, cancer, and bacterial/viral infections.

Green Synthesis of a Molecularly Imprinted Polymer Based on a Novel Thiophene-Derivative for Electrochemical Sensing

An environmentally friendly and sustainable approach was adopted to produce a molecularly imprinted polymer (MIP) via electropolymerization, with remarkable electrochemical sensing properties, tested in tyrosine (tyr) detection. The 2,2'-bis(2,2'-bithiophene-5-yl)-3,3'-bithianaphtene (BT2-T4) was chosen as functional monomer and MIP electrosynthesis was carried out via cyclic voltammetry on low-volume (20 μL) screen-printed carbon electrodes (C-SPE) in ionic liquid 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ((BMIM) TFSI). An easy and rapid washing treatment allowed us to obtain the resulting MIP film, directly used for tyr electrochemical detection, carried out amperometrically. The sensor showed a linear response in the concentration range of 15-200 μM, with LOD of 1.04 µM, LOQ of 3.17 μM and good performance in selectivity, stability, and reproducibility. Tyrosine amperometric detection was also carried out in human plasma, resulting in a satisfactory recovery estimation. The work represents the first use of BT2-T4 as a functional monomer for the production of a molecularly imprinted polymer, with a green approach afforded by using a few microliters of a room temperature ionic liquid as an alternative to common organic solvents on screen-printed carbon electrodes, resulting in a valuable system that meets the green chemistry guidelines, which is today an essential criterion in both research and application field.

Quantification of 2,4-dichlorophenoxyacetic acid in environmental samples using imprinted polyethyleneimine with enhanced selectivity as a selective adsorbent in ambient plasma mass spectrometry

Detection and quantification of various organic chemicals in the environment is critical to track their fate and control their levels. 2,4-Dichlorophenoxyacetic acid (2,4-D) is a widely applied phenoxy herbicide with potential toxicity to fish and other aquatic organisms. In this study, we address the need for improved detection of 2,4-D by introducing a novel analytical method for its quantification. This method relies on the selective extraction of 2,4-D using MIPs and their subsequent direct analysis using ambient plasma mass spectrometry. During the synthesis, MIPs with various degrees of glycidol (GLY) functionalization were obtained. Experimental data showed that MIPs with no GLY functionalization displayed the highest adsorption capacity. Conversely, MIPs with 30% GLY functionalization exhibited the greatest selectivity for 2,4-D, rendering them valuable for extraction of 2,4-D even in the presence of other contaminants. Finally, the obtained MIPs were applied for quantification of 2,4-D in various water samples through direct analysis using a specially designed ambient plasma mass spectrometry setup. This approach improved the detection limits by 200-fold compared to pure solution analysis. The quantification of 2,4-D in river water samples yielded highly satisfactory recoveries, demonstrating the effective utility of the proposed analytical setup for real-life water sample analysis.

Electrochemical determination of fenitrothion pesticide based on ultrathin manganese oxide nanowires/molybdenum titanium carbide MXene ionic nanocomposite and molecularly imprinting polymer

A novel molecularly imprinted electrochemical sensor is presented based on one-dimensional ultrathin manganese oxide nanowires/two-dimensional molybdenum titanium carbide MXene (MnO2NWs@Mo2TiC2 MXene) for fenitrothion (FEN) determination. After the synthesis of MnO2NWs@Mo2TiC2 MXene ionic nanocomposite was successfully completed with a facile hydrothermal and the pillaring methods, a new type molecular imprinted electrochemical sensor based on MnO2NWs@Mo2TiC2 MXene was constructed with cyclic voltammetry (CV) polymerization including pyrrole monomer and FEN target molecule. After the characterization studies including spectroscopic, electrochemical and microscopic methods, the analytical applications of the prepared sensor were performed. A linearity of 1.0×10-9-2.0×10-8 mol L-1 was obtained and the values of the quantification limit (LOQ) and the detection limit (LOD) were 1.0×10-9 mol L-1 and 3.0×10-10 mol L-1, respectively. The studies of selectivity, stability and reproducibility of the constructed sensor based on MnO2NWs@Mo2TiC2 nanocomposite and molecularly imprinting polymer (MIP) were carried out in detail. Finally, the developed sensor was applied to white flour samples with the values close to 100%.

Ultrasound-Assisted Extraction, Optimization, Phytochemical Screening and Analysis of Phenolics from Cycas Zeylanica and Antioxidant Activity Evaluation

The present study focuses on investigating the phytochemical screening of indigenous species, C. zeylanica, for the first time. The leaf extracts have been prepared using ultrasound-assisted methods to obtain the best extraction results using different time and temperature conditions such as 30, 60, and 90 min. and 30, 40, and 60 °C, respectively. The results have been optimized using response surface methodology. Under the optimal extraction conditions of 60 °C for 43.57 minutes, an extract was produced with a yield of 0.238 g and a high total phenolic content of 181.1965 mg GAE/g. The total phenolic content has been evaluated and the presence of gallic acid has been confirmed through the HPLC technique. The optimal extract (OE) showed excellent antioxidant activity for the DPPH assay, with an IC50 of 3.1 μg/ml. Finally, GC-MS profiling has been done to screen the volatile component of the plant extract.

Development of Highly Sensitive Fluorescent Sensors for Separation-Free Detection and Quantitation Systems of Pepsin Enzyme Applying a Structure-Guided Approach

Two fluorescent molecularly imprinted polymers (MIPs) were developed for pepsin enzyme utilising fluorescein and rhodamine b. The main difference between both dyes is the presence of two (diethylamino) groups in the structure of rhodamine b. Consequently, we wanted to investigate the effect of these functional groups on the selectivity and sensitivity of the resulting MIPs. Therefore, two silica-based MIPs for pepsin enzyme were developed using 3-aminopropyltriethoxysilane as a functional monomer and tetraethyl orthosilicate as a crosslinker to achieve a one-pot synthesis. Results of our study revealed that rhodamine b dyed MIPs (RMIPs) showed stronger binding, indicated by a higher binding capacity value of 256 mg g-1 compared to 217 mg g-1 for fluorescein dyed MIPs (FMIPs). Moreover, RMIPs showed superior sensitivity in the detection and quantitation of pepsin with a linear range from 0.28 to 42.85 µmol L-1 and a limit of detection (LOD) as low as 0.11 µmol L-1. In contrast, FMIPs covered a narrower range from 0.71 to 35.71 µmol L-1, and the LOD value reached 0.34 µmol L-1, which is three times less sensitive than RMIPs. Finally, the developed FMIPs and RMIPs were applied to a separation-free quantification system for pepsin in saliva samples without interference from any cross-reactors.

Hydrophilic molecularly imprinted resin-hexagonal boron nitride composite as a new adsorbent for selective extraction and determination of a carcinoid tumor biomarker in urine

BACKGROUND

The detection of disease biomarkers in biological samples plays an important role in early diagnosis and treatment of carcinoid tumor. However, due to the complexity of biological samples and the extremely low concentration of disease biomarkers, sample pretreatment is still the bottleneck of achieving accurate quantitative determination. In this work, new hydrophilic molecularly imprinted resin-hexagonal boron nitride (HMIR-h-BN) composites were developed and used as a new solid phase extraction (SPE) adsorbent for selective detection of 5-hydroxyindoleacetic acid (5-HIAA), a biomarker of carcinoid tumor, in urine.

RESULTS

Twenty-two types of HMIR-h-BN were successfully synthesized through growing hydrophilic molecularly imprinted resin on surface of activated two-dimensional h-BN nanosheets, and preparation parameters affecting the adsorption performance of HMIR-h-BN were investigated and optimized through adsorption experiments. HMIR-h-BN #19 (the ratio of resorcinol to hexamethylenetetramine: 6:3; the dosage of h-BN: 300 mg; the dosage of dummy template: 0.12 mmol; the imprinting time: 4 h) has demonstrated to be the optimal material for efficient separation and extraction of 5-HIAA. Combined with HPLC-UV, the limit of detection and the limit of quantification of 5-HIAA in real urine samples were 9.4 ng mL-1 and 31.3 ng mL-1, respectively, the coefficient of determination (R2) was 0.9996 in the linear range of 0.1-300 μg mL-1 and the relative recoveries ranged from 86.9 % to 97.7 % with RSD ≤5.1 %. Moreover, after being processed by HMIR-h-BN-SPE, there are no interferences from other peaks at the peak position of 5-HIAA.

SIGNIFICANCE

The HMIR-h-BN composite has been demonstrated to be capable of selective extraction of 5-HIAA from urine samples and have a significant purification effect. Based on the established HMIR-h-BN-SPE-HPLC-UV method, accurate quantitative determination of 5-HIAA in urine samples was achieved, which is expected to be applied in the early diagnostic of carcinoid tumor.

Recent Advances in Light-Driven Semiconductor-Based Micro/Nanomotors: Optimization Strategies and Emerging Applications

Micro/nanomotors represent a burgeoning field of research featuring small devices capable of autonomous movement in liquid environments through catalytic reactions and/or external stimuli. This review delves into recent advancements in light-driven semiconductor-based micro/nanomotors (LDSM), focusing on optimized syntheses, enhanced motion mechanisms, and emerging applications in the environmental and biomedical domains. The survey commences with a theoretical introduction to micromotors and their propulsion mechanisms, followed by an exploration of commonly studied LDSM, emphasizing their advantages. Critical properties affecting propulsion, such as surface features, morphology, and size, are presented alongside discussions on external conditions related to light sources and intensity, which are crucial for optimizing the propulsion speed. Each property is accompanied by a theoretical background and conclusions drawn up to 2018. The review further investigates recent adaptations of LDSM, uncovering underlying mechanisms and associated benefits. A brief discussion is included on potential synergistic effects between different external conditions, aiming to enhance efficiency-a relatively underexplored topic. In conclusion, the review outlines emerging applications in biomedicine and environmental monitoring/remediation resulting from recent LDSM research, highlighting the growing significance of this field. The comprehensive exploration of LDSM advancements provides valuable insights for researchers and practitioners seeking to leverage these innovative micro/nanomotors in diverse applications.

Flexible molecularly imprinted fiber library for the metabolic analysis of bisphenol F and ecological risk evaluation

Bisphenol F (BPF) has evoked global attentions due to its ubiquity and detrimental effects. Herein, a flexible molecularly imprinted fiber library was firstly proposed for the metabolic analysis of BPF in aquatic ecosystems. The library includes flexible single fibers and fiber arrays to precisely identify BPF and its metabolites with a wide range of polarities. Compared to commercial polyacrylate, the performance increased 11.56-570.98-fold. The adsorption capacity and the LogKow value were positively related. These arrays were used for the acquisition of environmental metabolomics data from aquatic ecosystems. In-depth data analysis showed that risk quotient was lower than 0.76, and bioaccumulation factor was lower than 2000 L/kg. Distribution concentration of BPF and its metabolites changed seasonally, and accumulation in sediment was much larger than that in surface water and hydrobionts. The risk is gradually increasing in sediment, but it does not reach high risk. The likelihood of bioaccumulation of parent compounds was greater than its metabolites. The library can be used in the metabolic diagnosis of pollutants with a broad range of polarities, providing a new method to acquire data for further ecological risk assessment, and offering a revolutionary strategy for environmental metabolomics investigation in aquatic ecosystems.

Enzyme-free ratiometric fluorescence and colorimetric dual-signal determination of glyphosate based on copper nanoclusters (ZIF/CuNCs) combined with blue carbon dots (bCDs)

A novel ratio fluorescent and colorimetric dual-signal sensing platform for detecting glyphosate based on blue carbon dots (bCDs) combined with ZIF/CuNCs nanomaterials that encapsulate copper nanoclusters (CuNCs) in a metal-organic framework (MOF). In principle, the immobilization of Cu2+ in ZIF/CuNCs results in complexation with imidazole in ZIF, leading to fluorescence quenching of ZIF/CuNCs, while the reference fluorophore bCDs remains unaffected. In addition, the colorimetric sensing strategy was based on the efficient peroxidase-like activity of bCDs binding to Cu2+, catalyzing H2O2 to generate OH. Under this condition, TMB could be oxidized to form blue oxTMB. However, when glyphosate was involved in the system, the fluorescence of ZIF/CuNCs was restored upon due to the strong chelation between Cu2+ and glyphosate, while the peroxidase-like activity of bCDs/Cu2+ decreased and resulted in the generation of fewer oxTMB, accompanied by a lighter blue color. The sensing platform was successfully applied to the determination of glyphosate in real samples of lake water and cabbage, demonstrating reliable and sensitive performance in practical applications.

A smartphone sensing platform for the sensitive and selective detection of clothianidin based on MIP-functionalized lanthanide MOF

A novel molecularly imprinted nanomaterial (Eu (BTC)-MPS@MIP) was synthesized on the surface of silanized europium-based metal-organic frameworks (Eu (BTC)-MPS) using 1, 3, 5-benzotrioic acid (H3BTC) as a ligand. The resulting Eu (BTC)-MPS@MIP was applied to constructing a smartphone sensing platform for the sensitive and selective detection of clothianidin (CLT) in vegetables. The synthesized Eu (BTC)-MPS@MIP demonstrated the successful formation of a typical core-shell structure featuring a shell thickness of approximately 70 - 80 nm. The developed sensing platform based on Eu (BTC)-MPS@MIP exhibited sensitivity in CLT detection with a detection limit of 4 µg/L and a linear response in the range 0.01 - 10 mg/L at excitation and emission wavelengths of 365 nm and 617 nm, respectively. The fluorescence sensing platform displayed excellent specificity for CLT detection, as evidenced by a high imprinting factor of 3.1. This specificity is primarily attributed to the recognition sites in the molecularly imprinted polymer (MIP) layer. When applied to spiked vegetable samples, the recovery of CLT ranged from 78.9 to 102.0%, with relative standard deviation (RSD) values falling between 2.2 and 6.2%. The quenching mechanism of Eu (BTC)-MPS@MIP toward CLT can be attributed to the inner filter effect (IFE), resulting from the optimal spectral overlap between the absorption spectrum of CLT and the excitation spectra of Eu (BTC)-MPS@MIP. The proposed method has the potential for extension to the detection of other pesticides by replacing the MIP recognition probes.

Evaluation of deep eutectic solvents in the synthesis of molecularly imprinted fibers for the solid-phase microextraction of triazines in soil samples

Nowadays, molecularly imprinted polymers (MIPs) are well established and are considered excellent materials for performing selective extractions. However, with the progressive implementation of the principles of green chemistry, it is necessary to find greener alternatives for both the synthesis and further use of MIPs in sample preparation. Accordingly, in the present work, different deep eutectic solvents (DES, both hydrophilic and hydrophobic), as an alternative to conventional organic solvents (i.e., toluene), were evaluated as porogens for the synthesis of imprinted fibers (monoliths), using fused silica capillaries as molds, for solid-phase microextraction (SPME). From this study, the polymer prepared with propazine (dummy template), methacrylic acid (monomer), ethylene glycol dimethacrylate (cross-linker), and a formic acid:L-menthol (1:1) DES (porogen) showed the best performance for selective rebinding of triazines. After optimization of the different variables involved in SPME, the new imprinted fibers were successfully applied to the extraction of target analytes (desisopropylatrazine, desethylatrazine, simazine, and atrazine) from soil sample extracts, providing relative recoveries ranging from 75.7 to 120.1%, reaching limits of detection within the range of 6.2-15.7 ng g-1, depending upon the analyte.