MIP Nanoparticles Research Articles

Removal of arsenic (V) from water using arsenic-imprinted nanoparticles

ABSTRACT The aim of this study is the synthesis of nanoparticles with selective arsenic recognition capability for the removal of arsenic from water. Arsenic recognition based molecularly imprinted (As(V)-MIP) were synthesized using the molecular imprinting technique via mini-emulsion polymerization. The synthesized As(V)-MIP nanoparticles were characterized using zeta sizer, zeta potential, FTIR, Raman spectroscopy, scanning electron microscopy (SEM), atomic force microscopy (AFM), and elemental analysis. The adsorption behavior of nanoparticles was investigated in a batch system at pH 4.0–9.0. The maximum adsorption capacity of As(V)-MIP nanoparticles was determined to be 54.29 mg As/g polymer at pH 5.0. Various parameters such as pH, concentration and adsorption time were examined to determine the optimum adsorption conditions. As(V)-MIP nanoparticle selectivity experiments were conducted in the presence of NO3 −, PO4 3−, and SO4 2− anions to determine the relative selectivity coefficients (K’). The experimental data showed a good correlation with the Langmuir isotherm equation and adherence of the adsorption process to pseudo-second-order kinetics was observed. Applying As(V)-MIP nanoparticles to real water sample showed up to 95.3% As(V) removal efficiency. Reusability experiments were performed by renewal of nanoparticles using a 1 M HNO3 solution containing 0.05% thiourea.

Highly selective molecularly imprinted polymer nanoparticles (MIP NPs)-based microfluidic gas sensor for tetrahydrocannabinol (THC) detection

A highly selective microfluidic integrated metal oxide gas sensor for THC detection is reported based on MIP nanoparticles (MIP NPs). We synthesized MIP NPs with THC recognition sites and coated them on a 3D-printed microfluidic channel surface. The sensitivity and selectivity of coated microfluidic integrated gas sensors were evaluated by exposure to THC, cannabidiol (CBD), methanol, and ethanol analytes in 300–700 ppm at 300 °C. For comparison, reference signals were obtained from a microfluidic channel coated with nonimprinted polymers (NIP NPs). The MIP and NIP NPs were characterized using scanning electron microscopy (SEM) and Raman spectroscopy. MIP and NIP NPs channels response data were combined and classified with 96.3% accuracy using the Fine KNN classification model in MATLAB R2021b Classification Learner App. Compared to the MIP NPs coated channel, the NIP NPs channel had poor selectivity towards THC, demonstrating that the THC recognition sites in the MIP structure enabled selective detection of THC. The findings demonstrated that the recognition sites of MIP NPs properly captured THC molecules, enabling the selective detection of THC compared to CBD, methanol, and ethanol.

Biomimetic sandwich assay of proteins with a photoelectrochemical sensor using molecularly imprinted targeting and self-ratiometric signaling

A novel photoelectrochemical (PEC) sensor based on dual-molecularly imprinted polymer (MIP) and self-ratiometric strategy was developed for measuring disease marker. The human papillomavirus 16 (HPV16) L1 protein was selected as a target model. The sensing elements contain TiO2 @Au as the PEC material, the MIP film as the primary artificial recognizer, and the alkaline phosphatase-labelled MIP nanoparticles (ALP-nanoMIPs) as the secondary artificial recognizer. Both MIPs were fabricated with a tailored and controllable process using merely a tiny epitope of the target protein as the templates. With the addition of L1 protein, a sandwich structure was formed and based on the dual-MIPs recognition. Ascorbic acid as the electron donor was produced and promoted the transient photocurrent response. Meanwhile, the steady photocurrent response decreased, arising from hinderance effect of the target protein rebinding for MIP film. This MIP sensor exhibited superior limit of detection (∼0.1 pg mL−1) and a broad linear range (0.28 pg mL−1 to 28 ng mL−1) for L1 protein. Good performance in terms of robustness, stability, selectivity, and repeatability was also confirmed. The designed MIP sensor has significant potential in extensive fields of low-cost antigen marker tests and healthcare screening.

Synthesis of fluorescent Molecularly Imprinted Polymer Nanoparticles Sensing Small Neurotransmitters with High Selectivity Using Immobilized Templates with Regulated Surface Density.

To develop nanosensors to probe neurotransmitters, we synthesized fluorescent-functionalized molecularly imprinted polymeric nanoparticles (fMIP-NPs) using monoamine neurotransmitters (serotonin and dopamine) immobilized on glass beads as templates. The size and fluorescence intensity of the fMIP-NPs synthesized with blended silane couplers increased with the presence of the target but were insensitive to the target analogs (L-tryptophan and L-dopa, respectively). However, when the template is anchored by a pure silane agent, both the fluorescence intensity and particle size of the fMIP-NPs were sensitive to the structural analog of the template. Another fMIP-NP was synthesized in the presence of poly([2-(methacryloyloxy)ethyl] trimethylammonium chloride (METMAC)-co-methacrylamide) grafted onto glass beads as a dummy template for acetylcholine. Acetylcholine increased the diameter and fluorescence intensity of the fMIP-NP, but choline had no effect. When the homopolymer of METMAC was used as a template, the fluorescence intensity and size of the resulting nanoparticles were not responsive to either acetylcholine or choline. The principle of increased fluorescence intensity due to specific interaction with the target substance is probably due to the increased distance between the fluorescent functional groups and decreased self-quenching due to the swelling caused by the specific interaction with the template. The results also indicate that MIP nanoparticles prepared by solid-phase synthesis can be used for targeting small molecules, such as the neurotransmitters addressed in this study, by adjusting the surface density of the template.

Molecularly Designed Ion-Imprinted Nanoparticles for Real-Time Sensing of Cu(II) Ions Using Quartz Crystal Microbalance.

A molecularly designed imprinting method was combined with a gravimetric nanosensor for the real-time detection Cu(II) ions in aqueous solutions without using expensive laboratory devices. Thus, 1:1 and 2:1 mol-ratio-dependent coordination modes between Cu(II), N-methacyloly-L histidine methyl ester (MAH) functional monomer complexes, and their four-fold and six-fold coordinations were calculated by means of density functional theory molecular modeling. Cu(II)-MIP1 and Cu(II)-MIP2 nanoparticles were synthesized in the size range of 80-100 nm and characterized by SEM, AFM and FTIR. Cu(II)-MIP nanoparticles were then conducted to a quartz crystal microbalance sensor for the real-time detection of Cu(II) ions in aqueous solutions. The effects of initial Cu(II) concentration, selectivity, and imprinting efficiency were investigated for the optimization of the nanosensor. Linearity of 99% was obtained in the Cu(II) ion linear concentration range of 0.15-1.57 µM with high sensitivity. The LOD was obtained as 40.7 nM for Cu(II)-MIP2 nanoparticles. The selectivity and the imprinting efficiency of the QCM nanosensor were obtained significantly in the presence of competitive ion samples (Co(II), Ni(II), Zn(II), and Fe(II)). The results are promising for sensing Cu(II) ions as environmental toxicants in water by combining molecularly designed ion-imprinted nanoparticles and a gravimetric sensor.

A novel enzyme-less uric acid voltammetric sensor based on highly selective nano-imprinted polymer synthesized utilizing [tetrabutyl ammonium]+-[urate]− ion-pair complex as template

Uric acid is well known as a critical biological compound and its concentration level in biological fluids such as urine and plasma is correlated to some serious disorders. The preparation of imprinted polymer for this compound poses challenges because of its highly hydrophilic characteristic, disabling its dissolving in the rationally applied low dielectric solvents. Herein, the uric acid-selective nano-sized molecularly imprinted polymer (nano-MIP) was synthesized utilizing the aprotic solvent of chloroform. This was executed by introducing an ion pair complex compound of [tetrabutyl ammonium]+-[urate]− which was created in an aqueous media followed by its extraction in an immiscible solvent of chloroform. The extraction condition was optimized to maximize the efficiency of uric acid extraction. The polymeric nanoparticles were utilized as the modifying agent of a carbon paste electrode (CPE). The nano-MIP/CPE electrode response to uric acid was excellently higher than both the non-imprinted polymer-modified CPE (nano-NIP/CPE) and CPE, demonstrating the presence and well-functioning of selective sites within the MIP nanoparticles. The responses of the NIP/CPE and CPE electrodes to uric acid were found to be the same which is a good indication of the absence of non-selective uric acid up-taking by the MIP material. The optimized sensor response to uric acid was linear in the concentration range of 0.6 to 10.0 µM. The detection limit was estimated to be 0.03 µM (3S/N). The fabricated sensor showed excellent selectivity against uric acid’s similar compounds and it was successfully applied for uric acid determination in urine samples.

Development of an ultrasensitive molecularly imprinted poly-(ortho-phenylenediamine) based sensor for the determination of melamine adulteration in milk and infant formula.

A sensitive molecularly imprinted poly‐(ortho‐phenylenediamine) electrochemical sensor was fabricated for selective melamine detection in milk and infant formula. The pencil graphite electrode (PGE) was modified by deposition of Au nanoparticles and reduced graphene oxide (RGO) on its surface. The fabrication of the electrode in various stages was monitored using cyclic voltammetry. The immobilized RGO, MIP, and gold nanoparticles on the PGE surface were morphologically characterized by field‐emission scanning electron microscopy (FESEM). Under the optimized conditions, the linear range and the limit of detection (LOD) were 10–17–10–8 M and 2.64 × 10–16 M (S/N = 3), respectively. The prepared sensor exhibited a good reproducibility and repeatability response. The recovery range of melamine‐spiked milk and infant formula was 92.7%–103.9% and 93.5%–105.8%, respectively. The sensor could apply successfully for melamine determination in milk and infant formula samples.

Testosterone Imprinted poly(HEMA‐MAA) Nanoparticles Based Surface Plasmon Resonance Sensor for Detection of Testosterone

AbstractThe selective, sensitive, and real‐time detection of testosterone was performed from both testosterone aqueous solution and artificial urine samples by using the advantages of surface plasmon resonance sensor (SPR) with molecular imprinting technique. The testosterone imprinted (MIP) and non‐imprinted (NIP) nanoparticle based poly(2‐hydroxyethyl methacrylate‐methacrylic acid (poly(HEMA‐MAA)) SPR sensors were prepared for detection of testosterone. After characterization of MIP and NIP nanoparticles, nanoparticles were attached on the SPR chip surfaces. The characterization of SPR sensor surfaces was carried out with characterization methods such as atomic force microscopy, ellipsometer and contact angle measurements. The real‐time measurements for detection of testosterone were performed with testosterone imprinted SPR sensor in the linear range of 0.5‐20 ng/mL concentration in testosterone aqueous solution. The imprinting factor and the limit of detection was found 4.16 and 0.049 ng/mL, respectively. The validation studies were performed with both SPR sensor and enzyme‐linked immunosorbent assay using testosterone samples prepared in artificial urine samples for the detection of testosterone.

Functional Nanoparticles with Magnetic 3D Covalent Organic Framework for the Specific Recognition and Separation of Bovine Serum Albumin.

Glutathione functionalized magnetic 3D covalent organic frameworks combined with molecularly imprinted polymer (magnetic 3D COF–GSH MIPs) were developed for the selective recognition and separation of bovine serum albumin (BSA). Ultrasonication was used to prepare magnetic 3D COFs with high porosity (~1 nm) and a large surface area (373 m2 g−1). The magnetic 3D COF–GSH MIP nanoparticles had an imprinting factor of 4.79, absorption capacity of 429 mg g−1, magnetic susceptibility of 32 emu g−1, and five adsorption–desorption cycles of stability. The proposed method has the advantages of a shorter equilibrium absorption time (1.5 h), higher magnetic susceptibility (32 emu g−1), and larger imprinting factor (4.79) compared with those reported from other studies. The magnetic 3D COF–GSH MIPs used with BSA had selectivity factors of 3.68, 2.76, and 3.30 for lysozyme, ovalbumin, and cytochrome C, respectively. The successful recognition and separation of BSA in a real sample analysis verified the capability of the magnetic 3D COF–GSH MIP nanoparticles.

Use of polymeric solid phase in synthesis of MIP nanoparticles for biotin

A polymer solid phase was tested as a replacement for the typical glass bead solid phase in the preparation of molecularly imprinted polymer nanoparticles (nanoMIPs). The cross-linked polymer, containing amine functionality, was synthesised and applied in the preparation of nanoparticles imprinted for biotin. The surface concentration of amine groups available for template immobilization was 1.75 mmol g−1 within the polymeric solid phase, contrasting with 0.48 mmol g−1 with the traditional glass solid phase. Biotin was covalently immobilized onto the surface of the polymer and nanoMIP production was repeated over several cycles using this polymer as a solid phase. The effect of multiple successive syntheses on the yields of nanoMIPs was investigated and compared with the yield of nanoMIPs produced on glass surfaces. The MIPs produced were characterized by DLS, SEM and SPR. It was concluded that the polymeric phase is superior to glass beads in terms of reproducibility and yield of nanoMIPs. However nanoMIPs synthesised on the polymeric support suffer from contamination caused by non-polymerised material leaking from the solid phase. Further improvement in the preparation of polymeric phases is needed prior their adoption as alternatives to glass beads.

Chemosensor Based on Molecularly Imprinted Nanoparticles for Selective Determination of Glyphosate

Glyphosate is a commonly used herbicide that can kill some weeds and grasses. Unfortunately, exposure to glyphosate is considered potentially harmful to humans. It may cause liver and kidney damage as well as can affect the endocrine system.1 Furthermore, the International Agency for Research on Cancer considers glyphosate as a probable carcinogen.2 Glyphosate determination often requires additional steps allowing quantification by commonly employed chromatographic techniques. Therefore, low-cost, rapid, and reliable ways to determine this pesticide are essential.We devised and fabricated an electrochemical chemosensor for the selective determination of the target toxin, glyphosate. As a recognition unit in this sensor, electroactive molecularly imprinted nanoparticles (nanoMIPs) with an internal redox probe were used.3 The MIP nanoparticles were synthesized using a solid-phase synthesis protocol.4 The nanoMIPs were characterized by several methods, including dynamic light scattering (DLS), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). The obtained nanoparticles were covalently immobilized on screen-printed platinum electrodes and successfully used for electrochemical determination of glyphosate in the absence of any external redox probe. Chemosensor fabricated that way demonstrated high sensitivity and selectivity with respect to structural analogs of glyphosate and other phosphate-containing analytes. The practical application of this self-reporting MIP-based chemosensor for detecting pesticide was further verified in river water samples with satisfying results. These results prove that our sensor's detectability is sufficient for the on-site detection of glyphosate pesticide.

Molecularly Imprinted Polymeric Nanoparticles by Precipitation Polymerization and Characterization by Quantitative NMR Spectroscopy.

An optimized synthetic methodology for the preparation of highly homogeneous MIP nanoparticles by the precipitation method is presented. A quantitative 1H NMR method that was developed to estimate template incorporation, polymer composition and conversion, and binding capacities and selectivities is also described. While the experiment presented here is exemplified by an MIP formulation using (±)-propranolol as the template, methacrylic acid as the functional monomer and ethylene glycol dimethacrylate as the crosslinker, the methods and techniques are applicable to other precipitation MIP systems.

Enhanced osteogenesis using poly (l-lactide-co-d, l-lactide)/poly (acrylic acid) nanofibrous scaffolds in presence of dexamethasone-loaded molecularly imprinted polymer nanoparticles

The aim of this work is to prepare nanofibrous scaffolds based on poly (l-lactide-d, l-lactide)/poly (acrylic acid) [PLDLLA/PAAc] blends in the presence of Dexamethasone [Dexa]-loaded poly (2-hydroxyethyl methacrylate) [HEMA] as molecular imprinted polymer [MIP] nanoparticles [NPs] for enhancing osteogenesis. By adding 10 wt% of PAAc to the PLDLLA and employing response surface methodology, the average diameter of the electrospun nanofibers is approximately 237 nm. To increase the osteogenesis performance of the optimized nanofibrous scaffolds, the MIP nanoparticles are synthesized using HEMA monomer and Dexa template with a molar ratio of 10 to 1. Accordingly, these crosslinked drug nanocarriers exhibit an average diameter of around 122 nm and imprinting factor of approximately 1.8, enabling to adsorb Dexa molecules around 57%. Afterward, the Dexa-loaded MIP NPs have capability of a controlled drug release with ultimate value of 60% during 72 h. The simultaneous use of PLDLLA/PAAc-10 nanofibrous scaffold and Dexa-loaded MIP NPs within the cultivation media of fibroblast and mesenchymal stem cells is carried out by thiazolyl blue assay and acridine/ethidium bromide staining as well as alkaline phosphate/calcium content test, and alizarin red staining. The results reveal the remarkable efficiency of the blend nanofibers besides the MIP containing Dexa, thereby using for bone tissue engineering applications, potentially.

Rapid and sensitive detection of synthetic cannabinoids JWH-018, JWH-073 and their metabolites using molecularly imprinted polymer-coated QCM nanosensor in artificial saliva

Synthetic cannabinoids (SCs), which are becoming increasingly popular, are an important public health issue considering the common abuse uses and serious adverse effects associated with intoxication. The analysis for controlling the increase in synthetic cannabinoids usage requires a faster and highly sensitive detection that rapidly developing class compounds. In this study, a piezoelectric nanosensor coated with a synthetic biomimetic recognition nanoparticles polymer was designed for the real-time and highly sensitive synthetic cannabinoids (SCs: JWH-018, JWH-073, JWH-018 pentanoic acid and JWH-073 butanoic acid) detection. Synthetic cannabinoids imprinted (MIP) and non-imprinted (NIP) nanoparticles were synthesized. Firstly, the characterization of MIP and NIP nanoparticles were studied by FTIR-ATR, scanning electron microscope, and size measurements. After, nanoparticles were spread onto a quartz crystal microbalance (QCM) chip. Different QCM chip surfaces were studied by contact angle, ellipsometry, and atomic force microscopy measurements. Selective rebinding of target analytes was monitored as a frequency shift measuring mass change with the QCM. Limit of detection values were calculated as 0.28, 0.3, 0.23, 0.29 pg/mL for these SCs in artificial saliva, respectively. The SCs-MIP QCM nanosensors displayed high sensitivity and selectivity in a wide concentration range of SCs (0.0005–1.0 ng/mL) in artificial saliva.

A high performance potentiometric sensor for lactic acid determination based on molecularly imprinted polymer/MWCNTs/PVC nanocomposite film covered carbon rod electrode

A novel nano-sized imprinted polymer/multi-walled carbon nanotube (MWCNTs)-based potentiometric sensor is introduced for lactic acid (LA) sensing in dairy products. The imprinted polymer was synthesized using allyl amine (AA) and ethylene glycol dimethacrylate as functional monomer and cross-linker, respectively. It was demonstrated that the amide linkage was created between LA and AA during copolymerization reaction which was finally hydrolyzed when removing template from the synthesized MIP. It was also shown that the MIP cavities, compatible with LA anion, were created during polymerization reaction which influenced the potentiometric response behavior of the MIP-based electrode. This novel potentiometric sensor is a carbon rod electrode, coated with a membrane consisting of the MIP nanoparticles (2.5%), MWCNTs (2%), dibutylphthalate (DBP) (65%), poly-vinyl chloride (PVC) (28.5%) and tetra phenyl phosphonium bromide (TPPB) (2%). The active ion sensed by the electrode is the LA anion formed at elevated pH condition. The sensor exhibited Nernstian slope of 30.3 ± 0.4 mVdecade−1 in the working concentration range of 1.0 × 10−1to 1.0 × 10−6 mol L−1 with detection limit of 7.3 × 10−7 mol L−1. The sensor displayed a stable potential response in the pH range of 5–8 and fast response time of less than 60 s. It exhibited also high selectivity over the interfering species. The proposed sensor was successfully applied for the determination of LA in real samples (milk and yoghurt).

Necklace-like Molecularly Imprinted Nanohybrids Based on Polymeric Nanoparticles Decorated Multiwalled Carbon Nanotubes for Highly Sensitive and Selective Melamine Detection.

In this study, molecularly imprinted nanohybrids with "necklace-like" nanostructures were developed based on self-assembled polymeric nanoparticles decorated multiwalled carbon nanotubes (MWCNTs) by employing melamine as template molecules. An amphiphilic copolymer poly(acrylic acid- co-(7-(4-vinylbenzyloxy)-4-methyl coumarin)- co-ethylhexyl acrylate) (poly(AA- co-VMc- co-EHA), PAVE) containing photosensitive coumarin units was synthesized first. Then, the PAVE copolymers were co-assembled with MWCNTs in the presence of template molecules, generating photosensitive molecularly imprinted nanohybrids (MIP-MWCNTs) with necklace-like structures. Subsequently, the MIP-MWCNTs nanohybrids were used to modify electrode surface followed by photo-polymerization of the coumarin units in the nanohybrids, leading to a network architectured complex film. After extracting melamine molecules by electrolysis, a melamine MIP sensor was successfully developed. The as-prepared sensor exhibited a significantly wide linear range (1.0 × 10-12-1.0 × 10-6 mol L-1) and a low detection limit (5.6 × 10-13 mol L-1) for melamine detection. High selectivity of the sensor toward melamine was well demonstrated with respect to other melamine analogues and interferents. Furthermore, the MIP sensor showed high stability and reproducibility. The excellent performance of the MIP sensor can be attributed to the unique nanostructure of the complex film provided by these necklace-like nanohybrids. On the one hand, the nanosized polymeric MIP nanoparticles along the MWCNTs increase the effective electrode surface area and thus offer a high melamine-binding capacity. On the other hand, the MWCNTs in MIP-MWCNTs nanohybrids serve as "electronic bridges" to accelerate the electron transfer among the complex MIP film. More importantly, the MIP sensor was practically used to monitor melamine in milk samples, demonstrating a promising feature for applications in the analysis of food like milk and other food products including milk powder, infant formula, and animal feed. Considering the ease of polymeric nanoparticles functionalization, the necklace-like nanohybrids would be extended to wider applications in many other sensors and devices.

Polyvinyl Alcohol/Polypyrrole/Molecularly Imprinted Polymer Nanocomposite as Highly Selective Chemiresistor Sensor for 2,4‐DNT Vapor Recognition

AbstractIn this research, a chemiresistor sensor coated with the polyvinyl alcohol/polypyrrole/molecularly imprinted polymer (PVA/PPy/MIP) nanocomposite was designed and fabricated to detect the vapor of 2,4‐DNT as a nitroaromatic explosive material. The molecularly imprinted polymer was composed of molecular nanoparticles containing cavities compatible with DNT; while, the nanoparticles were synthesized using PVA and glutaraldehyde as functionalized polymer and cross‐linking agent, respectively. Composition and chemical properties of the synthesized MIP and PPy nanoparticles were investigated using scanning electron microscopy (SEM), infrared Fourier transform spectroscopy (ATR‐FTIR), and X‐ray diffraction (XRD) analyses. Results indicated that the nanoparticles of polypyrrole and the synthesized MIP have an average particle sizes of 56 nm and 45 nm, respectively. Afterwards, sensor surface was coated by a thin layer of nanocomposite composed of PVA, the PPy and MIP nanoparticles. The prepared sensors were calibrated and performance‐tested in a static setup. The developed sensor was used to measure different concentrations (0.1–150 ppm) of the explosive vapor. The coated sensor presented a linear range of response within the concentration range of 0.1–70 ppm. Also, selectivity tests were carried out in the presence of DNT and vapor of other organic matters and the results indicated that the designed sensor possesses high sensitivity and selectivity toward DNT.

Synthesis of nano-sized timolol-imprinted polymer via ultrasonication assisted suspension polymerization in silicon oil and its use for the fabrication of timolol voltammetric sensor

A novel timolol voltammetric sensor based on the nano-sized molecularly imprinted polymer (nano-MIP)-modified carbon paste electrode was introduced. Timolol-imprinted polymers (MIP) were synthesized by the ultrasonic assisted suspension polymerization in silicon oil. The MIP nanoparticles were then embedded in a carbon paste (CP) electrode in order to prepare the nano-MIP-CP electrode. Timolol was extracted in the electrode for a definite time and then it was analyzed by square wave voltammetry, found to be an effective determination method. The electrode showed higher response to timolol, compared to the CP electrode, and CP electrode modified with non-imprinted polymer (nano-NIP-CP). Various factors, known to affect the response behavior of the nano-MIP-CP electrode, were investigated and optimized. The sensor exhibited distinct linear response ranges of 1.0×10−7–2.1×10−6M with the sensitivity of 71.523μAμM−1. The lower detection limit of the sensor was calculated to be 2.3×10−8M (S/N=3). The sensor was applied successfully for timolol determination in pharmaceutical formulations, blood serum and urine samples.

New immobilisation protocol for the template used in solid-phase synthesis of MIP nanoparticles

As a novel imprinting method, solid-phase synthesis has proven to be a promising approach to prepare polymer nanoparticles with specific recognition sites for a template molecule. In this method, imprinted polymer nanoparticles were synthesized using template immobilized on a solid support. Herein, preparation of immobilized templates on quartz chips through homogeneous route was reported as an efficient alternative strategy to heterogeneous one. The template molecule indole-3-butyric acid (IBA) was reacted with 3-aminopropyltriethoxysilane (APTES) to produce silylated template (IBA-APTES), and it was characterized by IR, 1H NMR and GC–MS. Then, the silylated template molecule was grafted onto the activated surfaces of quartz chip to prepare immobilized template (SiO2@IBA-APTES). The immobilization was confirmed by contact angle, XPS, UV and fluorescence measurement. Immobilization protocol has shown good reproducibility and stability of the immobilized template. MIP nanoparticles were prepared with high selectivity toward the molecule immobilized onto the solid surface. This provides a new approach for the development of molecularly imprinted nanoparticles.

Enzyme‐Initiated Free‐Radical Polymerization of Molecularly Imprinted Polymer Nanogels on a Solid Phase with an Immobilized Radical Source

AbstractAn enzyme‐mediated synthetic approach is described for the preparation of molecularly imprinted polymer nanoparticles (MIP‐NPs) in aqueous media. Horseradish peroxidase (HRP) was used to initiate the polymerization of methacrylate or vinyl monomers and cross‐linkers by catalyzing the generation of free radicals. To prevent entrapment of the enzyme in the cross‐linked polymer, and to enable it to be reused, HRP was immobilized on a solid support. MIPs based on 4‐vinylpyridine and 1,4‐bis(acryloyl)piperazine for the recognition of 2,4‐dichlorophenoxyacetic acid (2,4‐D) and salicylic acid were synthesized in an aqueous medium. MIPs for the protein trypsin were also synthesized. MIP nanoparticles with sizes between 50 and 300 nm were obtained with good binding properties, a good imprinting effect, and high selectivity for the target molecule. The reusability of immobilized HRP for MIP synthesis was shown for several batches.