Photocontrolled solid-phase extraction of guanine from complex samples using a novel photoresponsive molecularly imprinted polymer

Fundamentals, Synthetic Strategies and Applications of Non-Covalently Imprinted Polymers

Molecular imprinting has emerged as an important and practical technology to create economical and stable synthetic mimics of antibodies and enzymes. It has already found a variety of important applications, such as affinity separation, chemical/biological sensing, disease diagnostics, proteomics, bioimaging, controlled drug release, and catalysis. In the past decade, significant breakthroughs have been made in non-covalently imprinted polymers, from their synthesis through to their applications. In terms of synthesis, quite a few versatile and facile imprinting approaches for preparing MIPs have been invented, which have effectively solved some key issues in molecular imprinting. Additionally, important applications in several areas, such as sensors, proteomics and bioimaging, have been well demonstrated. In this review, we critically and comprehensively survey key recent advances made in the preparation of non-covalently imprinted polymers and their important applications. We focus on the state-of-art of this technology from three different perspectives: fundamentals, synthetic strategies, and applications. We first provide a fundamental basis for molecular imprinting technologies that have been developed, which is extremely helpful for establishing a sound understanding of the challenges in molecular imprinting. Then, we discuss in particular the major breakthroughs within the last ten years (2014-2024), with emphasis on new imprinting approaches, what strengths the breakthroughs can provide, and which new applications the properties of the prepared non-covalently imprinted polymers are fit for.

Preparation of high-efficiency titanium ion immobilized magnetic graphite nitride nanocomposite for phosphopeptide enrichment

BACKGROUND

Protein phosphorylation has been implicated in life processes including molecular interaction, protein structure transformation, and malignant disease. An in-depth study of protein phosphorylation may provide vital information for the discovery of early biomarkers. Mass spectrometry (MS)-based techniques have become an important method for phosphopeptide identification. Nevertheless, direct detection remains challenging because of the low ionization efficiency of phosphopeptides and serious interference from non-phosphopeptides. There is a great need for an efficient enrichment strategy to analyze protein phosphorylation prior to MS analysis.

RESULTS

In this study, a novel nanocomposite was prepared by introducing titanium ions into two-dimensional magnetic graphite nitride. The nanocomposite was combined with immobilized metal ion affinity chromatography (IMAC) and anion-exchange chromatography mechanisms for phosphoproteome research. The nanocomposite had the advantages of a large specific surface (412.9 m2 g-1), positive electricity (175.44 mV), and excellent magnetic property (35.7 emu g-1). Moreover, it presented satisfactory selectivity (α-casein:β-casein:bovine serum albumin = 1:1:5000), a low detection limit (0.02 fmol), great recyclability (10 cycles), and high recovery (92.8%). The nanocomposite demonstrated great practicability for phosphopeptides from non-fat milk, human serum, and saliva. Further, the nanocomposite was applied to enrich phosphopeptides from a more complicated specimen, A549 cell lysate. A total of 890 phosphopeptides mapping to 564 phosphoproteins were successfully detected with nano LC-MS.

SIGNIFICANCE

We successfully designed and developed an efficient analysis platform for phosphopeptides, which includes protein digestion, phosphopeptide enrichment, and MS detection. The MS-based enrichment platform was further used to analyze phosphopeptides from complicated bio-samples. This work paves the way for the design and preparation of graphite nitride-based IMAC materials for phosphoproteome analysis.

Effective Enrichment of Phosphopeptides Using Magnetic Polyoxometalate-Based Metal-Organic Frameworks

In this study, magnetic polyoxometalate-based metal-organic frameworks (Fe3O4-POMOFs) were designed and applied to the enrichment of phosphopeptides. Thanks to the abundant metal oxide and metal ion sites, the material had a strong affinity for phosphopeptides. Simultaneously, the high amount of amino and guanidyl groups provided hydrophilicity and positive charge for phosphopeptide capture. By coupling with MS detection, the established platform possessed good reusability, high sensitivity (0.01 fmol), and high selectivity (α-casein/β-casein/bovine serum albumin = 1:1:5000). Furthermore, the method was successfully used for the detection of phosphopeptides in nonfat milk, human serum, saliva, and A549 cell lysate, showing great potential for practical application.

Layer-by-layer assembly of multilayered double hydroxides/polyoxometalate-coated magnetic nanoparticles for highly efficient phosphopeptide enrichment

A layer-by-layer (LbL) assembly strategy was developed to prepare multilayered double hydroxide/polyoxometalate shell-coated magnetic nanoparticles. The introduction of functional shells not only offered abundant affinity sites of metal oxide and metal ions but also increased the surface area for the contact with targets. By combining the enrichment strategies of immobilized metal ion affinity chromatography and metal oxide affinity chromatography, the nanomaterial can capture phosphopeptides via a synergistic effect. The method presented a low detection limit of 0.1 fmol in combination with matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) analysis. The nanomaterial showed satisfactory selectivity (1:1:5000 M ratio of α-/β-casein/bovine serum albumin), good recovery (92.07%), high adsorption capacity (117.6 mg g^-1), and ten times reusability for capturing phosphopeptides.

A visible-light-responsive molecularly imprinted polyurethane for specific detection of dibenzothiophene in gasoline

Dibenzothiophene and its derivatives in gasoline and diesel would release sulfur oxides during combustion, and this is harmful to human health and the environment. This paper reports a method based on a visible-light-responsive molecularly imprinted polyurethane (VMIPU) to monitor trace dibenzothiophene in gasoline. The VMIPU was prepared by a polyaddition reaction using N,N-bis-(2-hydroxyethyl)-4-phenylazoaniline as the functional monomer, dibenzothiophene as the template molecule, diphenylmethane diisocyanate as the crosslinker and castor oil as the chain extender. The VMIPU showed good visible-light-response and specific adsorption for dibenzothiophene. The trans → cis photoisomerization rate constant of azobenzene chromophores in the VMIPU shows a linear relationship with the dibenzothiophene concentration in the range of 0-20 μmol L^-1. This was used to estimate trace dibenzothiophene in spiked gasoline with recoveries of 95.7-101.0% and relative standard deviations of 7.0-12.7%.

Amr AEG, Almehizia AA, Kamel AH. All-Solid-State Potentiometric Ion-Sensors Based on Tailored Imprinted Polymers for Pholcodine Determination

In recent times, the application of the use of ion-selective electrodes has expanded in the field of pharmaceutical analyses due to their distinction from other sensors in their high selectivity and low cost of measurement, in addition to their high measurement sensitivity. Cost-effective, reliable, and robust all-solid-state potentiometric selective electrodes were designed, characterized, and successfully used for pholcodine determination. The design of the sensor device was based on the use of a screen-printed electrode modified with multiwalled carbon nanotubes (MWCNTs) as a solid-contact transducer. Tailored pholcodine (PHO) molecularly imprinted polymers (MIPs) were prepared, characterized, and used as sensory receptors in the presented potentiometric sensing devices. The sensors exhibited a sensitivity of 31.6 ± 0.5 mV/decade (n = 5, R² = 0.9980) over the linear range of 5.5 × 10⁻⁶ M with a detection limit of 2.5 × 10⁻⁷ M. Real serum samples in addition to pharmaceutical formulations containing PHO were analyzed, and the results were compared with those obtained by the conventional standard liquid chromatographic approach. The presented analytical device showed an outstanding efficiency for fast, direct, and low-cost assessment of pholcodine levels in different matrices.

A hollow visible-light-responsive surface molecularly imprinted polymer for the detection of chlorpyrifos in vegetables and fruits

A visible-light-responsive azobenzene derivative, 3,5-dichloro-4-((2,6-dichloro-4-(methacryloyloxy)phenyl)diazenyl)benzoic acid, was synthesized and used as the functional monomer to fabricate a visible-light-responsive core-shell structured surface molecularly imprinted polymer (PS-co-PMAA@VSMIP). After removal of the sacrificial PS-co-PMAA core, a hollow structured surface molecularly imprinted polymer (HVSMIP) was obtained. Both the PS-co-PMAA@VSMIP and HVSMIP were used for the detection of chlorpyrifos, a moderately toxic organophosphate pesticide. They exhibited good visible-light-responsive properties (550 nm for trans→cis and 440 nm for cis→trans isomerization for an azobenzene chromophore) in ethanol/water (9:1, v/v). Compared with the PS-co-PMAA@VSMIP, the HVSMIP had a larger surface area, pore volume, binding capacity, imprinting effect, maximum chemical binding capacity, dissociation constant, and photo-isomerization rate. The HVSMIP was applied to detect trace chlorpyrifos in fruit and vegetable samples. This was achieved by measuring the trans→cis rate constant of the HVSMIP in the sample solution, with good recoveries, low relative standard deviations, and a low detection limit.

Visual detection of trace lead(II) using a forward osmosis-driven device loaded with ion-responsive nanogels

A simple and portable thermometer-type device based on forward osmosis-driven liquid column rising is developed for visual detection of trace Pb²⁺. The device consists of a top indicator tube, a chamber loaded with Pb²⁺-responsive poly(N-isopropylacrylamide-co-benzo-18-crown-6-acrylamide) (PNB) smart nanogels and a bottom semipermeable membrane. Upon the recognition of Pb²⁺, PNB smart nanogels undergo a Pb²⁺-induced hydrophobic to hydrophilic transition, which simultaneously causes the increase of osmotic pressure inside the device. Driven by this osmotic pressure difference, more Pb²⁺ solution flows into the device, causing the rise of the liquid column in the indicator tube, which can be directly observed by naked eyes. The relationship between the change of liquid column height and the Pb²⁺ concentration is investigated for the quantitative detection of Pb²⁺. With the proposed forward osmosis-driven device, trace Pb²⁺ as low as 10^-10 M in aqueous solutions can be detected. This method provides a novel and simple strategy for the visual detection of trace Pb²⁺.

Photoresponsive Surface Molecularly Imprinted Polymers for the Detection of Profenofos in Tomato and Mangosteen

As a moderately toxic organophosphorus pesticide, profenofos (PFF) is widely used in agricultural practice, resulting in the accumulation of a high amount of PFF in agricultural products and the environment. This will inevitably damage our health. Therefore, it is important to establish a convenient and sensitive method for the detection of PFF. This paper reports a photoresponsive surface-imprinted polymer based on poly(styrene-co-methyl acrylic acid) (PS-co-PMAA@PSMIPs) for the detection of PFF by using carboxyl-capped polystyrene microspheres (PS-co-PMAA), PFF, 4-((4-(methacryloyloxy)phenyl)diazenyl) benzoic acid, and triethanolamine trimethacrylate as the substrate, template, functional monomer, and cross-linker, respectively. PS-co-PMAA@PSMIP shows good photoresponsive properties in DMSO/H2O (3:1, v/v). Its photoisomerization rate constant exhibits a good linear relationship with PFF concentration in the range of 0~15 μmol/L. PS-co-PMAA@PSMIP was applied for the determination of PFF in spiked tomato and mangosteen with good recoveries ranging in 94.4-102.4%.

Preparation of Gas-Responsive Imprinting Hydrogel and Their Gas-Driven Switchable Affinity for Target Protein Recognition

Novel gas-responsive imprinting hydrogels were fabricated by combining N,N'-dimethylaminoethyl methacrylate gas-sensitive monomers, N,N'-methylenebis(acrylamide) cross-linkers, and human serum albumin (HSA) template proteins via a free radical polymerization. The hydrogel exhibited a reversible gas-responsive property upon N₂/CO₂ exchange. This result was supported by the evidences from hydrogen nuclear magnetic resonance spectroscopy and scanning electron microscopy. By applying this property to sensing application, a CO₂-responsive imprinted biosensor was originally designed on the surface of a glassy carbon electrode. The biosensor exhibited unique self-clean and self-recognition properties toward HSA proteins based on reversible conformational changes driven by N₂/CO₂ stimuli. Moreover, the proposed imprinted biosensor favored HSA proteins by showing satisfactory sensitivity and selectivity and a wider detection range with a low detection limit. As a rare example in imprint sensing, the biosensor was successfully applied to the HSA extraction from complex serum samples. With gas stimuli, the whole process was efficient, controllable, and harmless to the proteins. Thus, the developed biosensor may provide a new prospect in molecularly imprinted sensing applications.

Photo-stimulated "turn-on/off" molecularly imprinted polymers based on magnetic mesoporous silicon surface for efficient detection of sulfamerazine

In this study, novel photo-stimulated molecularly imprinted polymers based on magnetic mesoporous carrier surface were developed for selective identification and intelligent separation of sulfamerazine in complex samples. The photosensitive monomer of the molecularly imprinted polymers was azobenzene derivative 5-[(4-(methacryloyloxy)phenyl) diazenyl] isophthalic acid with stimulus reaction mechanisms, which has photoisomerization between trans and cis for N=N bonds. Further, the properties of the photo-stimulated molecularly imprinted polymers were further evaluated through several sets of adsorption experiments. It illustrated that the maximum adsorption amount is 0.45 mmol/L. By ultraviolet spectrophotometry, the material reaches typical characteristic peaks of photo sensitivity, and the cycle time is 16 min. Three adsorption and desorption processes were repeated, the adsorption rate reached 34.4%. Overall, the photo-stimulated molecularly imprinted polymers can enrich and separate determine sulfamerazine with high selectivity, which have good recovery for real samples.

Structural relationships for the design of responsive azobenzene-based lyotropic liquid crystals

Light-responsive binary (azobenzene + solvent) lyotropic liquid crystals (LCs) were investigated by structural modification of simple azobenzene molecules. Three benzoic acid-containing azobenzene molecules 4-(4-(hydroxyphenyl)diazenyl)benzoic acid (AZO1), 3-(4-(hydroxyphenyl)diazenyl)benzoic acid (AZO2) and 5-(4-(hydroxyphenyl)diazenyl)isophthalic acid (AZO3) were produced with various amide substitutions to produce tectons with a variety of hydrophobicity, size and branching. The LC mesophases formed by binary (azobenzene + solvent) systems with low volatility solvents dimethylsulfoxide (DMSO) and N,N-dimethylformamide (DMF) as well as the protic ionic liquids ethylammonium formate (EAF) and propylammonium formate (PAF), were investigated using a combination of small-angle X-ray and neutron scattering (SAXS and SANS) as well as polarising light microscopy (PLM). Increasing alkyl group length was found to have a strong influence on LC phase spacing, and changes in the position of substitution on the benzene ring influenced the preferred curvature of phases. UV-induced trans to cis isomerization of the samples was shown to influence ordering and optical birefringence, indicating potential applications in optical devices.

A photoresponsive molecularly imprinted polymer with rapid visible-light-induced photoswitching for 4-ethylphenol in red wine

The trans to cis isomerization of the azobenzene chromophore in most azobenzene-based photoresponsive molecularly imprinted polymers (MIPs) is initiated by UV irradiation. This limits the application of these materials in cases where UV light toxicity is an issue, such as in biological systems, food monitoring, and drug delivery. Herein we report a tetra-ortho-methyl substituted azobenzene, (4-[(4-methacryloyloxy)-2,6-dimethyl phenylazo]-3,5-dimethyl benzenesulfonic acid (MADPADSA). The photoswitching of MADPADSA could be induced by visible-light irradiation (550 nm for trans to cis and 475 nm for cis to trans) in 4-hydroxyethylpiperazineethanesulfonic acid (HEPES) buffer-ethanol (4:1, v/v) at pH 7.0, however, the photoisomerization was slow. With the use of MADPADSA as a functional monomer, NaYF₄:Yb³⁺,Er³⁺ as a substrate, 4-ethylphenol (4-EP) as a template, a novel photoresponsive surface molecularly imprinted polymer NaYF₄:Yb³⁺,Er³⁺@MIP was obtained. The NaYF₄:Yb³⁺,Er³⁺@MIP displayed rapid visible-light-induced photoswitching. The NaYF₄:Yb³⁺,Er³⁺ substrate could efficiently increase the trans to cis isomerization rate of the photoresponsive MIP on its surface, which was faster than that of the corresponding azobenzene monomer MADPADSA. Possible reasons for this effect were investigated by fluorescence spectroscopy. NaYF₄:Yb³⁺,Er³⁺@MIP displayed good specificity toward 4-EP with a specific binding constant (K_d) of 3.67 × 10^-6 mol L^-1 and an apparent maximum adsorption capacity (Q_max) of 10.73 μmol g^-1, respectively. NaYF₄:Yb³⁺,Er³⁺@MIP was applied to determine the concentration of 4-EP in red wine with good efficiency and a limit of detection lower than the value that could cause an unpleasant off-flavor.

Advancements of molecularly imprinted polymers in the food safety field

Molecularly imprinted technology (MIT) has been widely employed to produce stable, robust and cheap molecularly imprinted polymer (MIP) materials that possess selective binding sites for recognition of target analytes in food, such as pesticides, veterinary drugs, mycotoxins, illegal drugs and so on. Because of high selectivity and specificity, MIPs have drawn great attention in the food safety field. In this review, the recent developments of MIPs in various applications for food safety, including sample preparation, chromatographic separation, sensing, immunoassay etc., have been summarized. We particularly discuss the advancements and limitations in these applications, as well as attempts carried out for their improvement.

Nanosized Difunctional Photo Responsive Magnetic Imprinting Polymer for Electrochemically Monitored Light-Driven Paracetamol Extraction

Herein, a novel photoresponsive magnetic electrochemical imprinting sensor for the selective extraction of paracetamol from biological samples was designed. In particular, nanosized photoresponsive molecular imprinted polymers were prepared on the surface of magnetic Fe₃O₄ nanoparticles through living radical polymerization of azobenzene. The introduction of a magnetic-controlled glassy carbon electrode makes the immobilization and removal of nanosized photoresponsive molecular imprinted polymers on the magnetic-controlled glassy carbon electrode surface facilely operational. With the photoresponsive property, the sensor undergoes reversible release and uptake of paracetamol upon alternative irradiation at 365 and 440 nm basing on a configurational change of azobenzene monomer in the photoresponsive molecular imprinted polymers receptor sites. Simultaneously, these processes are monitored by the photoresponsive changes of electrochemical signal from paracetamol. Two linear ranges from 0.001 to 0.7 mmol L^-1 (R² = 0.96) and 0.7 to 7 mmol L^-1 (R² = 0.95) for paracetamol determination were obtained with a quantification limit of 0.000 86 mmol L^-1 and a detection limit of 0.000 43 mmol L^-1. The recoveries of paracetamol in the urine as determined by photoresponsive molecular imprinted polymers extraction were varied between 87.5% and 93.3%. As a consequence, combining photocontrolled selective extraction, interfacial stability from magnetic adsorption, and specifically electrochemical response, the photoresponsive molecular imprinted polymers sensor shows significant advantages for simultaneous separation, enrichment, and detection of trace paracetamol in biological samples.

Photoirradiation surface molecularly imprinted polymers for the separation of 6-O-α-d-maltosyl-β-cyclodextrin

Photoirradiation surface molecularly imprinted polymers for the separation of 6-O-α-d-maltosyl-β-cyclodextrin were synthesized using functionalized silica as a matrix, 4-(phenyldiazenyl)phenol as a light-sensitive monomer, and 6-O-α-d-maltosyl-β-cyclodextrin as a template. Fourier transform infrared spectroscopy results indicated that 4-(phenyldiazenyl)phenol was grafted onto the surface of functionalized silica. The obtained imprinted polymers exhibited specific recognition toward 6-O-α-d-maltosyl-β-cyclodextrin. Equilibrium binding experiments showed that the photoirradiation surface molecularly imprinted polymers obtained the maximum adsorption amount of 6-O-α-d-maltosyl-β-cyclodextrin at 20.5 mg/g. In binding kinetic experiments, the adsorption reached saturation within 2 h with binding capacity of 72.8%. The experimental results showed that the adsorption capacity and selectivity of imprinted polymers were effective for the separation of 6-O-α-d-maltosyl-β-cyclodextrin, indicating that imprinted polymers could be used to isolate 6-O-α-d-maltosyl-β-cyclodextrin from a conversion mixture containing β-cyclodextrin and maltose. The results showed that the imprinted polymers prepared by this method were very promising for the selective separation of 6-O-α-d-maltosyl-β-cyclodextrin.

"On-off" switchable tool for food sample preparation: merging molecularly imprinting technology with stimuli-responsive blocks. Current status, challenges and highlighted applications

Sample preparation still remains a great challenge in the analytical workflow representing the most time-consuming and laborious step in analytical procedures. Ideally, sample pre-treatment procedures must be more selective, cheap, quick and environmental friendly. Molecular imprinting technology is a powerful tool in the development of highly selective sample preparation methodologies enabling to preconcentrate the analytes from a complex food matrix. Actually, the design and development of molecularly imprinted polymers-based functional materials that merge an enhancement of selectivity with a controllable and switchable mode of action by means of specific stimulus constitutes a hot research topic in the field of food analysis. Thus, combining the stimuli responsive mechanism and imprinting technology a new generation of materials are emerging. The application of these smart materials in sample preparation is in early stage of development, nevertheless new improvements will promote a new driven in the demanding field of food sample preparation. The new trends in the advancement of food sample preparation using these smart materials will be presented in this review and highlighted the most relevant applications in this particular area of knowledge.

Molecularly Imprinted Polymers for Selective Extraction of Oblongifolin C from Garcinia yunnanensis Hu

Molecularly imprinted polymers (MIPs) were synthesized and applied for the selective extraction of oblongifolin C (OC) from fruit extracts of Garcinia yunnanensis Hu. A series of experiments and computational approaches were employed to improve the efficiency of screening for optimal MIP systems in the study. The molar ratio (1:4) was eventually chosen based on the comparison of the binding energy of the complexes between the template (OC) and the functional monomers using density functional theory (DFT) at the RI-PBE-D3-gCP/def2-TZVP level of theory. The binding characterization and the molecular recognition mechanism of MIPs were further explained using the molecular modeling method along with NMR and IR spectra data. The reusability of this approach was demonstrated in over 20 batch rebinding experiments. A mass of 140.5 mg of OC (>95% purity) was obtained from the 5 g extracts, with 2 g of MIPs with the best binding properties, through a gradient elution program from 35% to 70% methanol-water solution. At the same time, another structural analog, 46.5 mg of guttiferone K (GK) (>88% purity), was also obtained by the gradient elution procedure. Our results showed that the structural analogs could be separated from the crude extracts by the molecularly imprinted solid-phase extraction (MISPE) using a gradient elution procedure for the first time.

Molecularly imprinted polymers for sample preparation and biosensing in food analysis: Progress and perspectives

Molecularly imprinted polymers (MIPs) are biomimetics which can selectively bind to analytes of interest. One of the most interesting areas where MIPs have shown the biggest potential is food analysis. MIPs have found use as sorbents in sample preparation attributed to the high selectivity and high loading capacity. MIPs have been intensively employed in classical solid-phase extraction and solid-phase microextraction. More recently, MIPs have been combined with magnetic bead extraction, which greatly simplifies sample handling procedures. Studies have consistently shown that MIPs can effectively minimize complex food matrix effects, and improve recoveries and detection limits. In addition to sample preparation, MIPs have also been viewed as promising alternatives to bio-receptors due to the inherent molecular recognition abilities and the high stability in harsh chemical and physical conditions. MIPs have been utilized as receptors in biosensing platforms such as electrochemical, optical and mass biosensors to detect various analytes in food. In this review, we will discuss the current state-of-the-art of MIP synthesis and applications in the context of food analysis. We will highlight the imprinting methods which are applicable for imprinting food templates, summarize the recent progress in using MIPs for preparing and analysing food samples, and discuss the current limitations in the commercialisation of MIPs technology. Finally, future perspectives will be given.

Photoresponsive surface molecularly imprinted polymer on ZnO nanorods for uric acid detection in physiological fluids

A photoresponsive surface molecularly imprinted polymer for uric acid in physiological fluids was fabricated through a facile and effective method using bio-safe and biocompatible ZnO nanorods as a support. The strategy was carried out by introducing double bonds on the surface of the ZnO nanorods with 3-methacryloxypropyltrimethoxysilane. The surface molecularly imprinted polymer on ZnO nanorods was then prepared by surface polymerization using uric acid as template, water-soluble 5-[(4-(methacryloyloxy)phenyl)diazenyl]isophthalic acid as functional monomer, and triethanolamine trimethacryl ester as cross-linker. The surface molecularly imprinted polymer on ZnO nanorods showed good photoresponsive properties, high recognition ability, and fast binding kinetics toward uric acid, with a dissociation constant of 3.22×10(-5)M in aqueous NaH2PO4 buffer at pH=7.0 and a maximal adsorption capacity of 1.45μmolg(-1). Upon alternate irradiation at 365 and 440nm, the surface molecularly imprinted polymer on ZnO nanorods can quantitatively uptake and release uric acid.

Preparation of hemoglobin imprinted polymers based on graphene and protein removal assisted by electric potential

Hemoglobin (Hb) imprinted polymers based on graphene were prepared on the surface of Au electrode and protein removal assisted by electric potential was studied in detail.

Molecular imprinting: perspectives and applications

This critical review presents a survey of recent developments in technologies and strategies for the preparation of MIPs, followed by the application of MIPs in sample pretreatment, chromatographic separation and chemical sensing.

Review of the recent progress in photoresponsive molecularly imprinted polymers containing azobenzene chromophores

Photoresponsive molecularly imprinted polymers (PMIPs) containing azobenzene have received wide research attention in recent years and made notable achievements. This article reviews the recent developments on PMIPs containing azobenzene. Topics include the following: (i) brief introduction of azobenzene, molecularly imprinted polymers, and PMIPs containing azobenzene; (ii) progress in functional monomers, cross-linkers, and polymerization conditions; (iii) preparation methods, properties, applications, as well as advantages and disadvantages of conventional PMIPs; (iv) substrate, preparation method, and applications of photoresponsive surface molecularly imprinted polymers; and (v) some perspectives for further development of PMIPs containing azobenzene.