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Ultrathin molecularly imprinted polymer (MIP) films were deposited on the surfaces of ZnO nanorods (ZNRs) and nanosheets (ZNSs) by electropolymerization to afford extended-gate field-effect transistor sensors for detecting phenytoin (PHT) in plasma. Molecular imprinting efficiency was optimized by controlling the contents of functional monomers and the template in the precursor solution. PHT sensing was performed in plasma solutions with various concentrations by monitoring the drain current as a function of drain voltage under an applied gate voltage of 1.5 V. The reliability and reproducibility of the fabricated sensors were evaluated through a solution treatment process for complete PHT removal and PHT adsorption-removal cycling, while selectivity was examined by analyzing responses to chemicals with structures analogous to that of PHT. Compared with the ZNS/extracted-MIP sensor and sensors with non-imprinted polymer (NIP) films, the ZNR/extracted-MIP sensor showed superior responses to PHT-containing plasma due to selective PHT adsorption, achieving an imprinting factor of 4.23, detection limit of 12.9 ng/mL, quantitation limit of 53.0 ng/mL, and selectivity coefficients of 3–4 (against tramadol) and ~ 5 (against diphenhydramine). Therefore, we believe that the MIP-based ZNR sensing platform is promising for the practical detection of PHT and other drugs and evaluation of their proper dosages. [ABSTRACT FROM AUTHOR]

Novel detection method has been developed to explore changes in mechanical bending angles on a bilayer of polyethylene terephthalate (PET) and molecularly imprinted polymer (MIP). For an ovalbumin (OVA)-imprinted hydrogel layer, functional monomers were employed to achieve sufficient binding effect in the polymer matrix. The OVA amount added in the MIP precursor solution and the dimensions of OVA-imprinted hydrogel (MIH) strips were controlled to maximize the change in bending angles as an OVA sensing response within a valid detection range. The sensing behaviors were determined by monitoring the difference in the bending angles via protein adsorption based on the swelling-induced deformation of the OVA-extracted hydrogel (E-MIH) strip. The equilibrium adsorption capacity of the E-MIH strip was calculated via the Bradford protein assay. The detection limit, quantification limit, and imprinting factor were calculated. To compare the selectivity coefficients, the adsorption behaviors of three proteins were investigated. Finally, the reusability of the E-MIH strip was explored via repeated adsorption and extraction. Based on the results, the E-MIH strips demonstrated a promising protein sensing platform monitoring mechanical bending angles affected by swelling deformation. [ABSTRACT FROM AUTHOR]

Surface imprinting used for protein recognition in functional cavities is highly effective in imprinting biomacromolecules to avoid template encapsulation during the formation of a molecularly imprinted polymer (MIP) matrix. Herein, we introduce a facile surface-imprinting method based on two-step spin-coating and photopolymerization to design highly efficient imprinted sites on polymeric films to detect trypsin (TRY). Well-distributed template imprinting is successfully achieved for maximized sensing responses by controlling the composition of functional monomers and crosslinkers in the precursor solution and the concentration of TRY in the imprinting solution. The MIP film exhibits higher sensitivity (−841 ± 65 Hz/(μg/mL)) with a coefficient of determination of 0.970 and a higher imprinting factor of 4.5 in a 0.24 µg/mL TRY solution compared to the nonimprinted polymer (NIP) film. Moreover, the limit of detection and limit of quantification are calculated to be 25.33 and 84.42 ng/mL, respectively. Finally, the selectivity coefficient is within the range of 3.90–6.78 for TRY against other proteins. These sensing properties are superior to those of the corresponding nonimprinted polymer matrix. Thus, the proposed facile surface-imprinting method is highly effective for protein imprinting with high sensitivity and selectivity. [ABSTRACT FROM AUTHOR]

A visual observation of the bending angle changes for the novel and easy detection of proteins is introduced in this study by fabricating bovine serum albumin (BSA) imprinted hydrogel strips with a one sided 3D porous structure using a combination of polystyrene colloidal crystal templating and the molecular imprinting approach using BSA as the template protein and several functional monomers. [ABSTRACT FROM AUTHOR]

Molecularly imprinted polymers (MIPs) are a promising technology for sensing specific analytes. Structured MIP-coated quartz crystal microbalance sensors were developed for the detection of bisphenol A (BPA) using 2-dimethylaminoethyl methacrylate (DMAEMA) as a functional monomer. A simple unidirectional rubbing technique and a soft lithographic technique were used to fabricate convex hemispherical and hierarchical hemispherical MIP patterns, including a planar MIP film as a control. The two structured MIP films exhibited relatively higher imprinting factors and sensitivities compared with the planar MIP film and the selectivity coefficients of the structured MIP films were slightly increased due to the MIP structuring effect. [ABSTRACT FROM AUTHOR]

Surface imprinting used for template recognition in nanocavities can be controlled and improved by surface morphological changes. Generally, the lithographic technique is used for surface patterning concerning sensing signal amplification in molecularly imprinted polymer (MIP) thin films. In this paper, we describe the effects of silanized silica molds on sensing the properties of MIP films. Porous imprinted poly(MAA–co–EGDMA) films were lithographically fabricated using silanized or non-treated normal silica replica molds to detect 2,4-dichlorophenoxyacetic acid (2,4-D) herbicide as the standard template. The silanized mold MIP film (st-MIP) (Δf = −1021 Hz) exhibited a better sensing response than the non-treated normal MIP (n-MIP) (Δf = −978 Hz) because the imprinting effects, which occurred via functional groups on the silica surface, could be reduced through silane modification. Particularly, two non-imprinted (NIP) films (st-NIP and n-NIP) exhibited significantly different sensing responses. The st-NIP (Δfst-NIP = −332 Hz) films exhibited lower Δf values than the n-NIP film (Δfn-NIP = −610 Hz) owing to the remarkably reduced functionality against nonspecific adsorption. This phenomenon led to different imprinting factor (IF) values for the two MIP films (IFst-MIP = 3.38 and IFn-MIP = 1.86), which was calculated from the adsorbed 2,4-D mass per poly(MAA–co–EGDMA) unit weight (i.e., QMIP/QNIP). Moreover, it was found that the st-MIP film had better selectivity than the n-MIP film based on the sensing response of analogous herbicide solutions. As a result, it was revealed that the patterned molds' chemical surface modification, which controls the surface functionality of imprinted films during photopolymerization, plays a role in fabricating enhanced sensing properties in patterned MIP films. [ABSTRACT FROM AUTHOR]

In this study, protein-imprinted sensors with thin bulk films were electrochemically fabricated on gold-coated quartz crystal electrodes with hemispherical porous gold patterns for detecting trypsin (Trp). The gold patterns were electrodeposited on a polystyrene colloidal monolayer and then rinsed using toluene. For Trp imprinting on the gold patterned electrodes, a thin layer with a poly(o -phenylenediamine) and Trp protein was formed using a cyclic voltammetry method under optimized conditions. In addition, a two-dimensional molecularly imprinted polymer (2D-MIP) film was prepared on a planar gold electrode under the same conditions to compare to the dependence of Trp selective recognition on three-dimensional (3D) thin MIP structure, and each corresponding nonimprinted polymer film were constructed by electropolymerization, in the absence of Trp template, to compare molecular imprinting effects. The sensing properties of Trp imprinted sensors were investigated using electrochemical, such as cyclic voltammetry and electrochemical impedance spectroscopy, and microgravimetric methods to confirm the sensitivity and selectivity of MIP films. The 3D-MIP films demonstrated a higher imprinting factor (3.51) in 48-μg/mL of Trp concentration than the 2D-MIP film, and the limit of detection was calculated to be 70.9-ng/mL. In addition, the films exhibited higher electrochemical sensing responses due to increased Trp recognition by the effective molecular imprinting over a larger surface area. Thus, the construction of 3D-MIP films for the protein imprinting could provide excellent specificity, faster kinetics, and higher sensitivity for detecting macromolecular proteins than 2D-MIP films. [Display omitted] • Trypsin-imprinted sensors. • Gold-coated quartz crystal electrodes with hemispherical porous gold patterns. • Electropolymerized poly(o -phenylenediamine) for protein imprinting. • Electrochemical and microgravimetric sensing responses on molecularly imprinted polymers. • High sensitivity and selectivity in detecting trypsin. [ABSTRACT FROM AUTHOR]

Saxitoxin (STX), which is produced by certain dinoflagellate species, is a type of paralytic shellfish poisoning toxin that poses a serious threat to human health and the environment. Therefore, developing a technology for the convenient and cost-effective detection of STX is imperative. In this study, we developed an affinity peptide-imprinted polymer-based indirect competitive ELISA (ic-ELISA) without using enzyme–toxin conjugates. AuNP/Co 3 O 4 @Mg/Al cLDH was synthesized by calcining AuNP/ZIF-67@Mg/Al LDH, which was obtained by combining AuNPs, ZIF-67, and flower-like Mg/Al LDH. This synthesized nanozyme exhibited high catalytic activity (K m = 0.24 mM for TMB and 132.5 mM for H 2 O 2). The affinity peptide-imprinted polymer (MIP) was imprinted with an STX-specific template peptide (STX MIP) on a multi-well microplate and then reacted with an STX-specific signal peptide (STX SP). The interaction between the STX SP and MIP was detected using a streptavidin-coated nanozyme (SA-AuNP/Co 3 O 4 @Mg/Al cLDH). The developed MIP-based ic-ELISA exhibited excellent selectivity and sensitivity, with a limit of detection of 3.17 ng/mL (equivalent: 0.317 μg/g). Furthermore, the system was validated using a commercial ELISA kit and mussel tissue samples, and it demonstrated a high STX recovery with a low coefficient of variation. These results imply that the developed ic-ELISA can be used to detect STX in real samples. [ABSTRACT FROM AUTHOR]

Here, we developed extended-gate field-effect transistor (EG-FET)-based chemosensors with molecularly imprinted polymers (MIPs) on a gold-dendritic (AD) electrode to detect tumor necrosis factor-α (TNF-α) in serum. The poly(β-cyclodextrin) film was electrochemically prepared on the AD electrode using a potentiodynamic technique, followed by TNF-α immobilization by host-guest interaction. The MIP film was formed via electropolymerization of thiophene-3-amidoxime (T3A) monomer in PBS solution with one scan cycle at an applied voltage of 0–1.2 V. After electrochemical optimization, the sensing behavior (based on drain current, I ds) of the MIP films was investigated to explore the validity of the sensors, resulting in excellent reproducibility, reusability, and stability. Based on the Δ I ds – C TNF-α regression curves obtained in serum containing various analyte concentrations, the imprinting factor (IF) of MIP-based EG-FET sensor was 5.55. The selectivity was evaluated by comparing sensing property using analogous cytokine proteins (interleukin 1β [IL-1β] and interleukin-6 [IL-6]). The MIP-based EG-FET sensors exhibited high sensitivity (LOD: 0.55 pg/mL, LOQ: 1.82 pg/mL) and excellent selectivity (coefficient (α)> 3). Based on the excellent sensing performances, including high sensitivity and selectivity, excellent reproducibility, robustness, reusability, and stability, our (EG-FET)-based chemosensor with TNF-α-recognizing MIP film can be used for the early diagnosis and point–of–care of immune-related diseases. [Display omitted] • Highly selective detection of serum TNF-α was achieved. • Extended-gate field-effect transistors (EG-FETs) were employed for TNF-α sensing. • A poly (β-CD) layer was electrodeposited on gold dendrite electrodes. • The TNF-α template self-assembled on a poly(β-CD) layer. • Protein imprinting was performed on modified electrodes for TNF-α detection. [ABSTRACT FROM AUTHOR]

In this study, a specific binding peptide (BP1)-imprinted film comprising crosslinked poly(acrylamide-co-diallyamine-co-N,N′-methylenebisacrylamide) matrix was photochemically fabricated on a gold-coated quartz crystal electrode for detecting neutrophil gelatinase-associated lipocalin (NGAL), a promising biomarker of inflammatory bowel disease. Microcontact surface imprinting was performed using a BP1 template-adsorbed PDMS mold with a concave hemispherical array to form patterned films. The surface morphologies of the molecularly imprinted polymer (MIP) films were characterized using scanning electron microscopy (SEM), and the limit of detection (LOD, 0.07 μg/mL) and limit of quantification (LOQ, 0.24 μg/mL), including sensitivity and reproducibility, were investigated using electrochemical impedance spectroscopy (EIS). Moreover, the sensing properties of (NGAL-BP1)-imprinted MIP ("I-MIP")-assisted biosensors for detecting NGAL protein were investigated using differential pulse voltammetry (DPV) and EIS. Normalized current peak (I N) and impedance (R N) values linearly increased with NGAL ranging from 1 to 300 ng/mL. Moreover, the selectivity coefficient (k *) of NGAL proteins on the BP1-imprinted film was 3.5–5.8 against bovine serum albumin for the binding process in the entire low-concentration range owing to a high affinity between the imprinted BP1 peptide and target NGAL protein. Remarkable impedance difference was registered with respect to different stages of the Crohn's disease with the biosensors at the adsorption of NGAL proteins using samples from real patients. Moreover, the NGAL concentration measured using the developed (I-MIP)-assisted biosensors was comparable with that estimated using the commercially available enzyme-linked immunosorbent assay (ELISA). Therefore, peptide-imprinted biosensors based on electrochemical impedance sensing platforms are potentially promising for detecting macromolecular proteins. [Display omitted] • Neutrophil gelatinase-associated lipocalin (NGAL) differential pulse voltammetric and impedimetric biosensors. • Photopolymerized acrylamide for peptide imprinting. • Electrochemical impedimetric sensing responses on molecularly imprinted polymers (MIP). • High sensitivity and selectivity in determining trace NGAL. • Sensing behaviors of MIP-assisted biosensors proteins using samples from real patients with Crohn's disease. [ABSTRACT FROM AUTHOR]

In this study, protein-imprinted sensors were electrochemically fabricated on screen-printed carbon electrodes (SPCEs) for the cytokine interleukin-1β (IL-1β) detection. A double layer comprising poly(o -phenylenediamine) and poly(chromotrope 2R) with a template (i.e., IL-1β biomacromolecules) was formed through the cyclic voltammetry (CV) technique to modify the molecularly imprinted polymer (MIP) films on the SPCEs. The electrochemical sensing properties were investigated via CV and electrochemical impedance spectroscopy to confirm the imprinting effect on the MIP films. The results show that the MIP sensor has a highly sensitive response in the trace IL-1β solution (a few pg/mL) with a limit of detection of 0.23 pg/mL and a limit of quantification of 0.78 pg/mL. Furthermore, the MIP sensor showed high selectivity for IL-1β adsorption compared to other proteins. In summary, based on binary double layers, the impedance sensing platforms of electropolymerized MIP films show potential application in the practical detection of macromolecular proteins. [Display omitted] ● Cytokine interleukin-1β differential pulse voltammetric and impedimetric chemosensors. ● Electropolymerized chromotrope 2R for protein imprinting. ● A thin bulk imprinted films were optimized by controlling film thickness. ● Electrochemical impedimetric sensing responses on molecularly imprinted polymers. ● High sensitivity and selectivity in determining trace interleukin-1β. [ABSTRACT FROM AUTHOR]

[Display omitted] • Patterned formaldehyde-imprinted poly(TFMAA-–co–EGDMA–co–ST) films were fabricated using colloidal lithography and photosynthesis. • The porous MIP–QCM sensor showed the more enhanced sensing features rather than the planar MIP film. • The adsorption isotherms and kinetics of the formaldehyde-imprinted films were evaluated using nonlinear fitting models. • The selectivity features of the porous MIP film for formaldehyde detection were investigated. In this study, formaldehyde (HCHO)-imprinted hemispherical pore-patterned thin films, consisting of poly(2-(trifluoromethyl)acrylic acid–co–ethylene glycol dimethacrylate–co–styrene) (poly(TFMAA–co–EGDMA–co–ST)), were fabricated using the design of molecularly imprinted polymers (MIPs) and a subsequent lithographic micro/nanoimprinting method to amplify HCHO sensing signals in quartz crystal microbalance (QCM) sensors. Its molecular imprinting condition was optimized by controlling the added amount of a ST monomer in a MIP precursor solution. From the resonant frequency change with respect to HCHO adsorption, the imprinting factor of the porous MIP film was calculated to have a value of 2.38 and the sensitivity (0.132 mg g−1 ppm−1) of the porous MIP film exhibited markedly improved characteristics with respect to the porous non-imprinted polymer (NIP) film (0.05 mg g−1 ppm−1). The selectivity of the MIP-QCM sensors for the detection of HCHO was examined in the presence of other analogous toxic gases such as hydrogen chloride and hydrogen fluoride. The HCHO-absorbed porous MIP film had higher selective features with selectivity coefficients (k * ≈ 3.83 (HCl) and 4.46 (HF)) than porous NIP films (k * ≈ 1.53 (HCl) and 2.20 (HF)). Moreover, the relative selectivity of the porous MIP film appeared to be 2.03–2.5, which was higher than those of the planar MIP film (1.70–1.73). [ABSTRACT FROM AUTHOR]

• Iprodione-imprinted poly(MAA-co-TFMAA-co-EGDMA) is synthesized via ultraviolet (UV)-assisted photopolymerization. • Patterned MIP–QCM sensors have enhanced detection capabilities owing to the increased binding affinity. • The binding affinity of the iprodione MIP films is evaluated using the Freundlich isotherm model. • The selectivity of the patterned MIP films is investigated in the presence of two other fungicides. Despite being one of the most widely used fungicides in the agricultural industry, iprodione is a known water pollutant, and its continuous release into water sources is detrimental to human health. In this study, sensitive molecularly imprinted quartz crystal microbalance (MIP–QCM) sensors were prepared by fabricating two types of frisbee-like pillar patterns (MIP-3 μm and MIP-5 μm) onto the surface of gold quartz crystals for the real-time detection of iprodione in aqueous solutions. This study describes the synthesis of iprodione-imprinted poly(methacrylic acid-co-2-(trifluoromethyl)acrylic acid-co-ethylene glycol dimethacrylate), referred to as poly(MAA–co–TFMAA–co–EGDMA), in combination with a micro-contact printing technique (μ-CP), via ultraviolet (UV)-assisted photopolymerization. The patterned surfaces with increased surface-to-volume (S/V) ratio were characterized via atomic force microscopy (AFM), scanning force microscopy (SEM), and Fourier-transform infrared spectroscopy (FTIR). The planar imprinted films and the corresponding non-imprinted films were prepared as the control samples for evaluating the sensor's detection capabilities. According to the results, the MIP–QCM sensors had enhanced detection capabilities compared to their planar MIP counterparts owing to the increased binding affinity on the structured surfaces. The imprinting factor (IF) (i.e., Q e,MIP /Q e,NIP) indicated that the imprinting effects for each MIP film was comparatively assessed, resulting in the following order: 1.69 (MIP-plane) <2.21 (MIP-5 μm) <2.74 (MIP-3 μm). The LOQ and LOD values were 54.407 and 17.954 nM−1 (MIP-plane), 24.624 and 8.126 nM−1 (MIP-5 μm), and 62.423 and 20.600 nM−1 (MIP-3 μm). The binding affinity of the iprodione MIP films was evaluated using the Freundlich isotherm model, and the template amount detected in an iprodione aqueous solution ranged between 30 and 303 nM. Furthermore, the selectivity of the patterned MIP films for iprodione detection was also investigated in aqueous solutions in the presence of two other fungicides: pyrimethanil and procymidone. [ABSTRACT FROM AUTHOR]