Preparation of hybrid molecularly imprinted polymer with double-templates for rapid simultaneous purification of theophylline and chlorogenic acid in green tea

Quick separation and enrichment of chlorogenic acid and its analogues by a high-efficient molecularly imprinted nanoparticles and evaluation of antioxidant and hypoglycemic activities

Multiple interaction strategy to target was tried to use in the design of surface imprinting polymer. To validate this, active chlorogenic acid, a representative phenolic acid compound existing in many natural products, was selected as the template molecule and a magnetic molecularly imprinted nanoparticles (CGA-MMIPs) was synthesized. The characterizations indicated CGA-MMIPs was 20-50 nm, stable below 229.56 °C and had a saturation magnetic intensity of 17.90 emu/g. The prepared CGA-MMIPs exhibited high adsorption capacity (441.81 mg/g) and fast adsorption equilibrium for chlorogenic acid. It also was easy separation, high selectivity and good reusability, which was successfully used in quick separation of chlorogenic acid from Orthosiphon aristatus and Taraxacum mongolicum and Salvia miltiorrhiza. Moreover, the isolated substances possessed great antioxidant and hypoglycemic activities. These verified the strategy was useful and had huge prospects in the quick separation of chlorogenic acid or other phenolic acid compounds from natural products.

Molecularly imprinted polymers-ZnS quantum dots based composite sensor for optical detection of chlorogenic acid

Chlorogenic acid (CGA), a key phenolic acid found in coffee, fruits, vegetables, and herbs, has significant pharmacological activities, necessitating its accurate detection in complex matrices. In this study, an organic acrylate molecularly imprinted polymers-chitosan modified zinc sulphide quantum dots/polydopamine (MIPs-CS:ZnS QDs/PDA) based composite sensor for the detection of CGA has been designed. In MIPs shell, CGA served as template and 4-vinylpyridine and methacrylic acid as functional monomers, azobisisobutyronitrile acting as the initiator and ethylene glycol dimethacrylate as the cross-linker. Chitosan was incorporated to enhance the stability of ZnS QDs, while polydopamine was introduced during polymerization to improve adhesion and the selectivity of MIPs for CGA. Under ideal conditions, the composite sensor had shown a linear range of 0.02-11 μg/mL with detection limit of 8.9 × 10-3 μg/mL. The composite sensor showed imprinting factor of 6.3, and response time of 12 min. The sensor demonstrated good selectivity towards CGA, in the presence of interfering agents. Composite sensor was successfully applied to detect CGA in plant extracts, coffee and fruit juices, with recovery ranges from 88.93 to 98.49 %. The MIPs-CS:ZnS QDs/PDA composite sensor offers a simple and robust approach for CGA detection in real samples without requiring pre-treatment.

Synthesis of multi-template imprinted mesoporous silica nanoparticles via micelle-based interface imprinting strategy for specific and efficient extraction of five cinnamic acid derivatives from traditional Chinese medicines

Cinnamic acid derivatives, a crucial group of active components in traditional Chinese medicines (TCMs), encompass chlorogenic acid, caffeic acid, 4-hydroxycinnamic acid, ferulic acid, and cinnamic acid. These compounds exhibit a wide array of pharmacological activities, such as free radical scavenging, antioxidation, antibacterial effects, and antitumor activity. However, traditional separation and detection methods often suffer from poor selectivity, low extraction efficiencies, and insufficient sensitivity, thus limiting their applicability in studying the complex and diverse active component groups in TCMs. Herein, we proposed a novel micelle-based interface imprinting strategy by integrating multi-template imprinting with mesoporous silica. Specifically, caffeic acid, serving as an epitope template for chlorogenic acid, along with 4-hydroxycinnamic acid, ferulic acid, and cinnamic acid, collectively constituted a multi-template system. Micelles were generated using a cationic surfactant cetyltrimethylammonium bromide, which confined the four template molecules to the micelle surface through electrostatic attraction. Aminopropyltriethoxysilane, 3-ureidopropyltriethoxysilane, and benzyltriethoxysilane were selected as functional monomers, while tetraethyl orthosilicate were selected as both a cross-linker and a silicon source for the synthesis of multi-template imprinted mesoporous silica nanoparticles (MTIMSNs). The MTIMSNs demonstrated high specificity and impressive adsorption capacity for chlorogenic acid, caffeic acid, 4-hydroxycinnamic acid, ferulic acid, and cinnamic acid, with maximum cross-reactivities of 8.8 %, 7.6 %, 6.8 %, 9.5 %, and 11.5 %, respectively, and corresponding adsorption capacities of 3.712, 4.114, 4.843, 3.517, and 2.814 mg/g, respectively. The MTIMSNs-based affinity extraction coupled with high performance liquid chromatography have been successfully applied to the determination of the five cinnamic acid derivatives in Taraxaci Herba.

Preparation of Hybrid Molecularly Imprinted Polymers Based on 3-Triethoxysilylpropyl Methacrylic Amide for Solid-Phase Extraction of Gatifloxacin From Lake Water

A novel molecularly imprinted polymer (MIP) against gatifloxacin based on a hybrid monomer (3-triethoxysilylpropyl methacrylic amide, APTES-MAA) was reported. In this study, the imprinted monolith was synthesized with gatifloxacin as template, ethylene glycol dimethacrylate (EGDMA) as cross-linker, and APTES-MAA as functional monomer in a mixture of acetonitrile and isooctane as porogen via an optimization based on density functional theory (DFT). The polymers were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, and mercury porosimetry. The resulting hybrid MIPs (HMIPs) showed high affinity and selectivity to the template molecule with an imprinted factor of 16.28 ± 0.53, which was 6.1 times higher than that of the traditional methacrylic acid-based MIP. The MIP was used as an adsorbent in solid-phase extraction of lake water with gatifloxacin. The recovery was 96.52 ± 2.69%. The method exhibits the advantageous features of cost-effectiveness and high sensitivity, rendering it a promising approach for analyzing organic pollutants in water.

Molecularly imprinted polymers in the analysis of chlorogenic acid: A review

Chlorogenic acid, a phenolic compound, is prevalent across various plant species and has been known for its pharmacological advantages. Health care experts have identified chlorogenic acid as a potential biomarker for treatment of a wide range of illnesses. Therefore, achieving efficient extraction and analysis of chlorogenic acid from plants and their products has become essential. Molecularly imprinted polymers (MIPs) are highly effective adsorbent for the extraction of chlorogenic acid from complex matrices. Currently, there is a lack of comprehensive review article that consolidate the methods utilized for the purification of chlorogenic acid through molecular imprinting. In this context, we have surveyed the common approaches employed in preparing MIPs specifically designed for the analysis of chlorogenic acid, including both conventional and newly developed. This review discusses the advantages, limitations of polymerization techniques and proposed strategies to produce more efficient MIPs for chlorogenic acid enrichment in complex samples. Additionaly, we present advanced imprinting methods for designing MIPs, which improve the adsorption capacity, sensitivity and selectivity towards chlorogenic acid.

Hybrid molecularly imprinted polymers for targeted separation and enrichment of 10-hydroxycamptothecin in Camptotheca acuminata Decne

The molecularly imprinted polymer was synthesized using 3-aminopropylthiosilane-methacrylic acid monomer (APTES-MAA) as the functional monomer and 10-hydroxycamptothecin (HCPT) as the template, based on computer simulation. The hybrid molecularly imprinted polymers (HMIPs) were characterized using Fourier transform infrared spectroscopy, thermogravimetric analysis, particle size measurement, scanning electron microscopy and energy dispersive X-ray spectroscopy. It has been shown that HMIPs are irregularly shaped and porous, with particle sizes ranging mainly from 130 to 211 nm. At 298 K, the HMIPs exhibit a maximum adsorption capacity of 8.35 mg·g-1 for HCPT and demonstrate good adsorption specificity (α = 5.38). The pseudo-second-order reaction mechanism suggests that the equilibrium adsorption capacity of HCPT on HMIPs is 8.11 mg·g-1. Finally, HCPT was successfully separated and enriched from the extract of Camptotheca acuminata Decne. seeds using HMIPs.

Functionalized nano cellulose double-template imprinted aerogel microsphere for the targeted enrichment of taxanes

Paclitaxel, a diterpenoid isolated from the bark of Taxus wallichiana var. chinensis (Pilger) Florin, is currently showing significant therapeutic effects against a variety of cancers. Baccatin III (Bac) and 10-Deacetylbaccatin III (10-DAB) are in great demand as important precursors for the synthesis of paclitaxel. This work aims to develop a simple, rapid and highly selective, safe, and non-polluting molecularly imprinted material for 10-DAB and Bac enrichment. In this study, we innovatively prepared molecularly imprinted materials with nanocellulose aerogel microspheres and 2-vinylpyridine (2-VP) as a bifunctional monomer, and 10-DAB and Bac as bis-template molecules. In particular, functionalized nanocellulose dual-template molecularly imprinted aerogel microsphere (FNCAG-DMIM) were successfully synthesized by the bifunctional introduction of functional nanocellulose aerogel microsphere (FNCAG) modified with Polyethyleneimine (PEI) as a carrier and functional monomer, which provided a large number of recognition sites for bimodal molecules. FNCAG-DMIM showed high specificity for 10-DAB and Bac specific assays. Under the optimal experimental conditions, the adsorption capacities of FNCAG-DMIM for 10-DAB and Bac reached 52.27 mg g-1 and 53.81 mg g-1, respectively. In addition, it showed good reliability and practicality in the determination of real samples. The present study extends the research on the synthesis of natural functional monomers by molecularly imprinted materials and opens up new horizons for the targeted isolation of plant compounds by dual-template molecularly imprinted materials.

Computer-aided design of molecularly imprinted polymer reinforced by double hybrid monomers for selective purification of hydroxycamptothecin

A kind of hydroxycamptothecin (HCPT) hybrid molecularly imprinted polymer (AT/MA-HMIPs) with high selectivity and hard silicon skeleton was successfully prepared based on double hybrid monomers. The relationship between templates and functional monomers was studied through computer molecular simulation and experiments. Three single-monomer molecularly imprinted polymers were prepared as controls. The Langmuir isotherm and pseudo-second-order kinetic models were found to fit well with the adsorption results. The maximum adsorption capacity was 18.79 mg/g, and equilibrium was reached within 20 min. Moreover, it shows excellent selectivity (imprinting factor is 10.73) and good recoverability (after 10 adsorption-desorption cycles, the adsorption capacity only decreases by 7.75%) for HCPT. The purity of HCPT can reach 80.86% after being put into a solid phase extraction column and used in an actual sample, and the yield was 61.43%. This study lays the fundament for the development of excellent HCPT molecularly imprinted composites.

Ultra-High Adsorption Capacity of Core-Shell-Derived Magnetic Zeolite Imidazolate Framework-67 as Adsorbent for Selective Extraction of Theophylline

A core-shell-derived structural magnetic zeolite imidazolate framework-67 (Fe₃O₄-COOH@ZIF-67) nanocomposite was fabricated through a single-step coating of zeolite imidazolate framework-67 on glutaric anhydride-functionalized Fe₃O₄ nanosphere for the magnetic solid-phase extraction (MSPE) of theophylline (TP). The Fe₃O₄-COOH@ZIF-67 nanocomposite was characterized through scanning electron microscopy, transmission electron microscopy, energy dispersive X-ray spectrometry, Fourier transform infrared spectroscopy, Zeta potential analysis, X-ray diffraction, Brunauer-Emmett-Teller, and vibrating sample magnetometer. The material has a high specific surface area and good magnetism, which maintains the regular dodecahedron structure of ZIF-67 without being destroyed by the addition of Fe₃O₄-COOH nanospheres. The Fe₃O₄-COOH@ZIF-67 can rapidly adsorb TP mainly through the strong coordination interaction between undercoordinated Co²⁺ on ZIF-67 and -NH from imidazole of TP. The adsorption and desorption conditions, such as the amount of adsorbent, adsorption time, pH value, and elution solvent, were optimized. The kinetics of TP adsorption on Fe₃O₄-COOH@ZIF-67 was found to follow pseudo-second-order kinetics. The Langmuir model fits the adsorption data well and the maximum adsorption capacity is 1764 mg/g. Finally, the developed MSPE-HPLC method was applied in the enrichment and analysis of TP in four tea samples and rabbit plasma. TP was not detected in oolong tea and rabbit plasma, and its contents in jasmine tea, black tea, and green tea are 5.80, 4.31, and 1.53 μg/g, respectively. The recoveries of spiked samples are between 74.41% and 86.07% with RSD in the range of 0.81-3.83%. The adsorption performance of Fe₃O₄-COOH@ZIF-67 nanocomposite was nearly unchanged after being stored at room temperature for at least 80 days and two consecutive adsorption-desorption cycles. The results demonstrate that Fe₃O₄-COOH@ZIF-67 nanocomposite is a promising magnetic adsorbent for the preconcentration of TP in complex samples.

Fluorescent Imprinted Nanoparticles for Sensing of Chlorogenic Acid in Coffee Extracts

Green coffee beans are particularly rich in chlorogenic acids (CGAs), and their identification and quantification are usually performed by HPLC, coupled with mass spectrometry (LC-MS). Although there are a few examples of molecularly imprinted polymers (MIPs) for chlorogenic acid (5-CQA) recognition present in the literature, none of them are based on optical fluorescence, which is very interesting given its great sensitivity. In the present manuscript, fluorescent polymeric imprinted nanoparticles were synthetized following the non-covalent approach using hydrogenated 5-O-caffeoylquinic acid (H-5-CQA) as the template. The capability of the polymer to bind 5-CQA was evaluated by HPLC and fluorescence. A real sample of coffee extract was also analyzed to verify the selectivity of the polymer. Polymer fMIP01, containing 4-vinylpyridine and a naphtalimide derivative as monomers, showed a good response to the fluorescence quenching in the range 39 μM-80 mM. In the real sample, fMIP01 was able to selectively bind 5-CQA, while caffeine was not recognized. To demonstrate this, there is a promising system that can be exploited in the design of an optical sensor for 5-CQA detection. Polymer fMIP01 was immobilized by physical entrapment on a functionalized glass surface, showing a quenching of fluorescence with an increase of the CGA concentration between 156 μM and 40 mM.

Physiological Effects of Green-Colored Food-Derived Bioactive Compounds on Cardiovascular and Metabolic Diseases

Cardiovascular and metabolic diseases are a leading cause of death worldwide. Epidemiological studies strongly highlight various benefits of consuming colorful fruits and vegetables in everyday life. In this review, we aimed to revisit previous studies conducted in the last few decades regarding green-colored foods and their bioactive compounds in consideration of treating and/or preventing cardiovascular and metabolic diseases. This review draws a comprehensive summary and assessment of research on the physiological effects of various bioactive compounds, mainly polyphenols, derived from green-colored fruits and vegetables. In particular, their health-beneficial effects, including antioxidant, anti-inflammatory, anti-diabetic, anti-obesity, cardioprotective, and lipid-lowering properties, will be discussed. Furthermore, the bioavailability and significance of action of these bioactive compounds on cardiovascular and metabolic diseases will be discussed in detail.

Computational modeling, fabrication, and characterization of the deep eutectic solvent-based green molecular cage for selective metronidazole extraction from plasma followed by UHPLC with diode array detector determination

Four ternary deep eutectic solvents were computationally designed and synthesized, being used as candidate functional monomers in metronidazole molecular imprinting polymer synthesis, allowing selective extraction and determination by ultra high performance liquid chromatography with diode array detection. In terms of metronidazole selective extraction, the best results were obtained by (deep eutectic solvent)₂ :(ethylene glycol dimethacrylate)₁₁ , in which deep eutectic solvent is the functional monomer constructed by combining three components in 6:6:2 ratios of choline chloride:ethylene glycol:methacrylic acid. The effects of different parameters on molecular imprinted solid-phase extraction of metronidazole were thoroughly explored through screening design and response surface methodology. The adsorption mechanism findings show that the adsorption data are primarily fitted on the Freundlich model based on higher correlation coefficient. Kinetic experiments have shown that the mechanism of adsorption fits the pseudo-second-order model. The best extraction recovery (96.5%) was obtained in 25-min elution time, desorption temperature of 40°C, and 1.0 mL ACN as eluent. Metronidazole was measured by a validated ultra high performance liquid chromatography with diode array detection method. The calibration of the method was linear in the range of 0.1-10 μg/mL with limits of detection and quantification of 0.03 and 0.1 μg/mL, respectively. The method was successfully applied for the determination of metronidazole in human plasma.

Immobilization of Molecularly Imprinted Polymer Nanoparticles onto Surfaces Using Different Strategies: Evaluating the Influence of the Functionalized Interface on the Performance of a Thermal Assay for the Detection of the Cardiac Biomarker Troponin I

We demonstrate that a novel functionalized interface, where molecularly imprinted polymer nanoparticles (nanoMIPs) are attached to screen-printed graphite electrodes (SPEs), can be utilized for the thermal detection of the cardiac biomarker troponin I (cTnI). The ultrasensitive detection of the unique protein cTnI can be utilized for the early diagnosis of myocardial infraction (i.e., heart attacks), resulting in considerably lower patient mortality and morbidity. Our developed platform presents an innovative route to develop accurate, low-cost, and disposable sensors for the diagnosis of cardiovascular diseases, specifically myocardial infraction. A reproducible and advantageous solid-phase approach was utilized to synthesize high-affinity nanoMIPs (average size = 71 nm) for cTnI, which served as synthetic receptors in a thermal sensing platform. To assess the performance and commercial potential of the sensor platform, various approaches were used to immobilize nanoMIPs onto thermocouples or SPEs: dip coating, drop casting, and a covalent approach relying on electrografting with an organic coupling reaction. Characterization of the nanoMIP-functionalized surfaces was performed with electrochemical impedance spectroscopy, atomic force microscopy, and scanning electron microscopy. Measurements from an in-house designed thermal setup revealed that covalent functionalization of nanoMIPs onto SPEs led to the most reproducible sensing capabilities. The proof of application was provided by measuring buffered solutions spiked with cTnI, which demonstrated that through monitoring changes in heat transfer at the solid-liquid interface, we can measure concentrations as low as 10 pg L^-1, resulting in the most sensitive test of this type. Furthermore, preliminary data are presented for a prototype platform, which can detect cTnI with shorter measurement times and smaller sample volumes. The excellent sensor performance, versatility of the nanoMIPs, and reproducible and low-cost nature of the SPEs demonstrate that this sensor platform technology has a clear commercial route with high potential to contribute to sustainable healthcare.

Fabrication of acid-resistant imprinted layer on magnetic nanomaterials for selective extraction of chlorogenic acid in Honeysuckle

The common elution process of molecularly imprinted polymers (MIPs) is carried out in an acidic medium, which greatly affects the stability and reusability of synthetic MIPs, especially for magnetic MIPs. In this study, we fabricated an acid-resistant imprinted layer formed by phase-transitioned lysozyme on magnetic nanomaterials for selective extraction of chlorogenic acid in Honeysuckle, which often coexists with structural analogs. The newly designed acid-resistant imprinted layer can not only protect the internal magnetic core from denudation and dissolution, but also maintain the integrity of the imprinted layer during the elution process. The resultant magnetic MIPs exhibited good stability with no change on morphology after the repeatedly eluting process, and satisfactory reusability that can be used at least ten adsorption-desorption cycles with almost no decrease for adsorption capacity. In addition, the resultant materials possess satisfactory magnetism, uniform morphology with typical core-shell structure, stable crystallization, and good adsorption performance showing on high adsorption amount (10.82 mg g^-1), fast kinetic equilibrium time (as short as 30 min), and satisfactory selectivity (IF = 2.85, SC > 1.5). At last, the obtained magnetic MIPs as adsorbents coupled with HPLC were successfully used to selective extract CGA in Honeysuckle samples with the high recoveries in the range of 92.0-104.4%, and the contents of CGA in Honeysuckle samples from the different origin are calculated in the range of 0.98%-1.24%.

Selective separation and inexpensive purification of paclitaxel based on molecularly imprinted polymers modified with ternary deep eutectic solvents

Paclitaxel (PTX) is a powerful anticancer natural product, with its separation and purification having been widely studied. In this work, new molecular imprinted polymers (MIPs) using deep eutectic solvents (DESs) with different molar ratios were prepared as functional monomers. These were then used as adsorbents in solid phase extraction (SPE) for the separation of PTX from its structural analogs. The polymers were characterized by energy disperive X-rays (EDX), scanning electron microscopy (SEM), thermogravimetric analysis (TGA) and fourier transform infrared spectroscopy (FT-IR). The results suggested that the formative regular DES-MIPs had an even pore-size distribution and a large specific surface area. The dynamic adsorption and static adsorption showed that the DES-MIPs had excellent adsorption performance, with a maximum adsorption capacity and optimum adsorption time of 87.08 mg/g and 180 min, respectively. The selective adsorption experiments showed that the material had outstanding selectivity, and the maximum selectivity factor was 6.20. For stability, after six consecutive adsorption and desorption cycles, the DES-MIPs maintained the perfect stability and reusability. Furthermore, the fabricated SPE column was successfully utilized for extracting and eluting PTX. This study provides a reliable protocol for the separation and purification PTX from its structural analogs and the DES-MIPs materials have excellent potential application value in pharmaceutical industry.

Molecularly Imprinted Polymers and Surface Imprinted Polymers Based Electrochemical Biosensor for Infectious Diseases

Owing to their merits of simple, fast, sensitive, and low cost, electrochemical biosensors have been widely used for the diagnosis of infectious diseases. As a critical element, the receptor determines the selectivity, stability, and accuracy of the electrochemical biosensors. Molecularly imprinted polymers (MIPs) and surface imprinted polymers (SIPs) have great potential to be robust artificial receptors. Therefore, extensive studies have been reported to develop MIPs/SIPs for the detection of infectious diseases with high selectivity and reliability. In this review, we discuss mechanisms of recognition events between imprinted polymers with different biomarkers, such as signaling molecules, microbial toxins, viruses, and bacterial and fungal cells. Then, various preparation methods of MIPs/SIPs for electrochemical biosensors are summarized. Especially, the methods of electropolymerization and micro-contact imprinting are emphasized. Furthermore, applications of MIPs/SIPs based electrochemical biosensors for infectious disease detection are highlighted. At last, challenges and perspectives are discussed.

Ordered macroporous molecularly imprinted polymers prepared by a surface imprinting method and their applications to the direct extraction of flavonoids from Gingko leaves

In this work, to improve the availability of the recognition sites of molecularly imprinted polymers (MIPs), ordered macroporous molecularly imprinted polymers (OMMIPs) were facilely prepared by grafting a quercetin-MIPs layer on the pore walls of the ordered macroporous thiol group functionalized silica. The pore structures were characterized by FTIR, Raman, SEM, BET and TGA measurements. The results indicated that OMMIPs possessed a nanoscale polymer layer, a more regular macroporous structure and a greater porosity compared with the traditional bulk MIPs (TBMIPs). The polymer content of OMMIPs was about 49.7%. Kinetic and isothermal adsorption experiments indicated that OMMIPs exhibited higher affinity and selectivity towards quercetin than its structural analogues. Moreover, OMMIPs could improve the intra-particle adsorption and thus provide a significant improvement in recognition sites availability over TBMIPs. Using the quercetin-OMMIPs as SPE sorbent, quercetin was directly extracted from the crude Gingko leaves extract with a satisfying selectivity and elution recovery.

Fabrication of Water-Compatible Molecularly Imprinted Resin in a Hydrophilic Deep Eutectic Solvent for the Determination and Purification of Quinolones in Wastewaters

A novel water-compatible molecularly imprinted resin was prepared in a green solvent deep eutectic solvent (DES). Resorcinol and melamine, as functional monomers with an abundant hydrophilic group, such as –OH, –NH₂ and –NH–, were introduced into the molecularly imprinted resin (MIR). Three DESs (choline chloride-ethylene glycol, tetramethylammonium bromide-ethylene glycol and tetramethylammonium chloride-ethylene glycol) were used to synthesize the molecularly imprinted resin and the resulting deep eutectic solvent-based molecularly imprinted resins were characterized by particle size analysis, elemental analysis, scanning electron microscopy, Fourier transform infrared spectroscopy and thermogravimetric analysis. The resulting deep eutectic solvent-based molecularly imprinted resins were then applied to the adsorption of quinolones (ofloxacin) in water. The adsorption process of deep eutectic solvent-based molecularly imprinted resin followed the static adsorption model, Langmuir isotherm (R² ≥ 0.9618) and kinetic model pseudo-second-order (R² > 0.9814). The highest theory adsorption ability of the three kinds of deep eutectic solvent-based molecularly imprinted resins was more than 23.79 mg/g. The choline chloride-ethylene glycol-based MIR was applied to solid-phase extraction for the determination and purification of quinolones (e.g., ciprofloxacin and ofloxacin). The detection limit of deep eutectic solvent-based molecularly imprinted resin-solid-phase extraction method was less than 0.018 mg/L. The recoveries of the deep eutectic solvent-based molecularly imprinted resin-solid-phase extraction method at three spiked levels were 88.7–94.5%, with a relative standard deviation of ≤4.8%. The novel deep eutectic solvent-based molecularly imprinted resin-solid-phase extraction method is a simple, selective and accurate pre-treatment method and can be used to determine the quinolones in environmental water.

Progress in Molecularly Imprinted Polymers for Biomedical Applications

BACKGROUND

Molecularly Imprinted Polymers (MIPs), a type of biomimetic materials have attracted considerable interest owing to their cost-effectiveness, good physiochemical stability, favorable specificity and selectivity for target analytes, and long shelf life. These materials are able to mimic natural recognition entities, including biological receptors and antibodies, providing a versatile platform to achieve the desirable functionality for various biomedical applications.

OBJECTIVE

In this review article, we introduce the most recent development of MIPs to date. We first highlight the advantages of using MIPs for a broad range of biomedical applications. We then review their various methods of synthesis along with their latest progress in biomedical applications, including biosensing, drug delivery, cell imaging and drug discovery. Lastly, the existing challenges and future perspectives of MIPs for biomedical applications are briefly discussed.

CONCLUSION

We envision that MIPs may be used as potential materials for diverse biomedical applications in the near future.

Novel controllable hydrophilic thermo-responsive molecularly imprinted resin adsorbent prepared in water for selective recognition of alkaloids by thermal-assisted dispersive solid phase extraction

A novel controllable hydrophilic thermo-responsive molecularly imprinted resin (T-MIR) with a switchable zipper-like architecture was synthesized in the aqueous phase and applied to the selective recognition and extraction of alkaloids by positive temperature regulation. In this synthesis process of T-MIR, 2-acrylamide-2- methylpropanesulfonic acid (AMPS) and acrylamide (AAm) were coupled as zipper-like thermo-responsive monomers, resorcinol, and melamine as hydrophilic monomers, formaldehyde as a cross-linker, and berberine chloride (BerbC) as the template. The resulting T-MIR achieved the controlled rebinding and release of BerbC from temperature stimuli (25-45 °C) and the adsorption process followed the Langmuir isotherm (R²>0.99856) and pseudo-second-order kinetic model (R²>0.98138). The highest theory adsorption ability (33.44 mg/g) and recognition ability (imprinting factor: 4.71) of T-MIR was activated between poly(AMPS) and poly(AAm) in the zipper-like architecture at 35 °C. T-MIR was then applied to the selective recognition alkaloids by dispersive solid phase extraction. The limit of detection and limit of quantitation of the method were less than 0.025 mg/L and 0.082 mg/mL, respectively. The recoveries of the proposed method at three spiked levels were 96.8-100.8%, with a relative standard deviation of less than 4.8%. In contrast to previous thermo-responsive materials, this switchable zipper-like hydrophilic T-MIR with good adsorption, specificity recognition, and excellent temperature controllable properties provides a unique alternative to the selective recognition and controlled rebind-release alkaloids by the temperature signal.

Hydrophobic ionic liquid modified thermoresponsive molecularly imprinted monolith for the selective recognition and separation of tanshinones

A hydrophobic ionic liquid modified thermoresponsive molecularly imprinted monolith was synthesized using N-isopropylacrylamide as a thermoresponsive monomer and a long-chain hydrophobic ionic liquid as an auxiliary modification monomer. The ionic-liquid-modified thermoresponsive molecularly imprinted polymer was characterized by scanning electron microscopy and Fourier transform infrared spectroscopy. When the column temperature was 50°C, the synthesized monolithic column was successfully applied to the selective separation of homologue tanshinones within 7 min and eluted only by water (mobile phase) (theoretical plates more than 1.00 × 10⁵ per meter). The negative Gibbs free energy (≤-2.37) values showed that the transfer of the tanshinones from the mobile phase to the stationary phase on this monolithic column was a thermodynamically spontaneous process. Good linearity of the five tanshinones by thermoresponsive monolith was obtained in the range of 0.100-25.0 μg/mL. The limit of detection (S/N = 3) and limit of quantitation (S/N = 10) were less than 0.0390 and 0.0630 μg/mL, respectively, with a relative standard deviation of <4.8%. In this proposed thermoresponsive chromatography method, the separation of homologue analytes can be achieved by changing the column temperature, and the use of water as the mobile phase would decrease the economic cost and organic pollution.

Molecular imprinted polymers based on magnetic chitosan with different deep eutectic solvent monomers for the selective separation of catechins in black tea

Two types of molecular-imprinted polymers-based magnetic chitosan with facile deep eutectic solvent-functional monomers (Fe3 O4 -CTS@DES-MIPs) were synthesized and applied as adsorbents in magnetic solid-phase extraction (MSPE) for the selective recognition and separation of (+)-catechin, (-)-epicatechin, and (-)-epigallocatechin gallate in black tea. The obtained Fe3 O4 -CTS@DES-MIPs were characterized by Fourier transform infrared spectroscopy and field emission scanning electron microscopy. The selective recognition ability was examined by adsorption experiments. The actual amounts of (+)-catechin, (-)-epicatechin, and (-)-epigallocatechin gallate extracted from black tea using Fe3 O4 -CTS@DES-MIPs by the MSPE method were 13.10, 6.32, and 8.76 mg/g, respectively. In addition, the magnetic Fe3 O4 -CTS@DES-MIPs showed outstanding recognition and selectivity. Therefore, it can be used to separate bioactive compounds from black tea. The new-type of DES adopted as the functional monomer in this paper provides a new perspective for the recognition and separation of bioactive compounds.

A portable synthesis of water-soluble carbon dots for highly sensitive and selective detection of chlorogenic acid based on inner filter effect

In this work, a simple and facile hydrothermal method for synthesis of water-soluble carbon dots (CDs) with malic acid and urea, and were then employed as a high-performance fluorescent probe for selective and sensitive determination of chlorogenic acid (CGA) based on inner filter effect. The as-synthesized CDs was systematically characterized by Transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Energy disperse spectroscopy (EDS), UV-vis absorption spectroscopy, spectrofluorophotometry, and the results indicated that the sizes of CDs were mainly distributed in the range of 1.0nm-3.0nm with an average diameter of 2.1nm. More significantly, the as-prepared CDs possessed remarkable selectivity and sensitivity towards CGA with the linear range of 0.15μmolL^-1-60μmolL^-1 and the detection limit for CGA was 45nmolL^-1 (3σ/k). The practical applications of CDs for detection of CGA have already been successfully demonstrated in Honeysuckle. This sensitive, selective method has a great application prospect in the pharmaceutical and biological analysis field owing to its simplicity and rapidity for the detection of CGA.

Selective extraction of theophylline from plasma by copper-doped magnetic microspheres prior to its quantification by HPLC

The authors describe the preparation of copper-doped magnetic microspheres (Cu-Fe₃O₄) by a solvothermal method. Due to their good magnetic property and high affinity for compounds containing an imidazole moiety (containing N-H), they are excellent adsorbents for such compounds as tested by eighteen compounds. Specifically, a method has been developed for magnetic solid-phase extraction (MSPE) of theophylline (TP) from plasma. The method enables selective enrichment of TP over many potential interferents that can occur in plasma. Following elution with alkaline methanol, TP was quantified by HPLC-UV at a detection wavelength of 272 nm. Under the optimized conditions, a linear response is found for the 0.02 to 20 μg·mL^-1 concentration range, and the limit of detection is as low as 3 ng·mL^-1. Recoveries from spiked samples range from 91.2 to 100.4%, and the repeatabilities are between 2.9 and 12% (for n = 6). The method was successfully applied to the determination of TP in rabbit and rat plasma. Graphical abstract Copper-doped magnetic microspheres are described that show good magnetic property and high affinity for compounds containing an imidazole moiety (containing an N-H group). They were successfully applied to the selective extraction of theophylline in plasma.

Application of novel ternary deep eutectic solvents as a functional monomer in molecularly imprinted polymers for purification of levofloxacin

A series of ecofriendly ternary deep eutectic solvents (DESs) with different molar ratios were prepared as candidate functional monomers. Three of the optimal ternary DESs as functional monomers were applied to the preparation of molecularly imprinted polymers (MIPs). After synthesis, the proposed polymers were characterized by elemental analysis (EA), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), Brunauer-Emmett-Teller surface area measurements (BET) and Fourier transform infrared spectroscopy (FT-IR). These MIPs based on ternary DESs with different molar ratios exhibited different absorption capacities of levofloxacin. A sample of levofloxacin (500ng) was dissolved in a millet extractive (10mL). All MIPs were used as SPE adsorbents to purify the extracts. According to characterization result, the ternary DES-3 (1:3:1.5) was joined in the synthetic process of MIP-1. The green ternary DES-3-based MIPs had the best selectivity recovery for levofloxacin (91.4%) from the millet extractive. The best selectivity of MIP-1 was attributed to the novel monomer (ternary DES) in the preparation of the materials. Overall, ternary DES-based MIPs have potential applications as media in many research areas.

Hand-in-hand RNA nanowire-based aptasensor for the detection of theophylline

Theophylline is a popular drug for many respiratory diseases. However, certain toxic side effects may be developed and the narrow safety range raises the demand for sensitive methods to constantly monitor theophylline levels. This study presents an electrochemical approach towards theophylline detection based on the recognition by split RNA aptamers. Target induced construction of hand-in-hand RNA nanowire on the electrode surface could further absorb silver nanoparticles (Ag NPs) as electrochemical species. When theophylline is not present, RNA probes are stable and their conformations remain unchanged. In contrast, theophylline is able to trigger the hairpin opening of RNA probe and subsequent self-assembly of RNA nanowire, which could be captured by DNA tetrahedron on the electrode interface. After further decorating Ag NPs on the nanowire, silver stripping current is measured to reveal initial theophylline concentration. The developed sensing strategy shows excellent specificity and sensitivity with the limit of detection of 50nM. Its practical utility is demonstrated by quantitative determination of theophylline levels in complex biological samples.