The microcontact imprinting of proteins: the effect of cross-linking monomers for lysozyme, ribonuclease A and myoglobin

Effect of Various Carbon Electrodes on MIP-Based Sensing Proteins Using Poly(Scopoletin): A Case Study of Ferritin

Sensitivity in the sub-nanomolar concentration region is required to determine important protein biomarkers, e.g., ferritin. As a prerequisite for high sensitivity, in this paper, the affinity of the functional monomer to the macromolecular target ferritin in solution was compared with the value for the respective molecularly imprinted polymer (MIP)-based electrodes, and the influence of various surface modifications of the electrode was investigated. The analytical performance of ferritin sensing was investigated using three different carbon electrodes (screen-printed carbon electrodes, single-walled-carbon-nanotube-modified screen-printed carbon electrodes, and glassy carbon electrodes) covered with a scopoletin-based MIP layer. Regardless of the electrode type, the template molecule ferritin was mixed with the functional monomer scopoletin, and electropolymerization was conducted using multistep amperometry. All stages of MIP preparation were followed by evaluating the diffusional permeability of the redox marker ferricyanide/ferrocyanide through the polymer layer by differential pulse voltammetry. The best results were obtained with glassy carbon electrodes. The MIP sensor responded up to 0.5 µM linearly with a Kd of 0.30 µM. Similar results were also obtained in solution upon the interaction of scopoletin and ferritin using fluorescence spectroscopy, resulting in the quenching of the scopoletin signal, with a calculated Kd of 0.81 µM. Moreover, the binding of 1 µM ferritin led to 49.6% suppression, whereas human serum albumin caused 8.6% suppression.

Imprinted Polymers on the Route to Plastibodies for Biomacromolecules (MIPs), Viruses (VIPs), and Cells (CIPs)

Around 30% of the scientific papers published on imprinted polymers describe the recognition of proteins, nucleic acids, viruses, and cells. The straightforward synthesis from only one up to six functional monomers and the simple integration into a sensor are significant advantages as compared with enzymes or antibodies. Furthermore, they can be synthesized against toxic substances and structures of low immunogenicity and allow multi-analyte measurements via multi-template synthesis. The affinity is sufficiently high for protein biomarkers, DNA, viruses, and cells. However, the cross-reactivity of highly abundant proteins is still a challenge.

The Use of Sensors in Blood-Brain Barrier-on-a-Chip Devices: Current Practice and Future Directions

The application of lab-on-a-chip technologies in in vitro cell culturing swiftly resulted in improved models of human organs compared to static culture insert-based ones. These chip devices provide controlled cell culture environments to mimic physiological functions and properties. Models of the blood-brain barrier (BBB) especially profited from this advanced technological approach. The BBB represents the tightest endothelial barrier within the vasculature with high electric resistance and low passive permeability, providing a controlled interface between the circulation and the brain. The multi-cell type dynamic BBB-on-chip models are in demand in several fields as alternatives to expensive animal studies or static culture inserts methods. Their combination with integrated biosensors provides real-time and noninvasive monitoring of the integrity of the BBB and of the presence and concentration of agents contributing to the physiological and metabolic functions and pathologies. In this review, we describe built-in sensors to characterize BBB models via quasi-direct current and electrical impedance measurements, as well as the different types of biosensors for the detection of metabolites, drugs, or toxic agents. We also give an outlook on the future of the field, with potential combinations of existing methods and possible improvements of current techniques.

Molecularly imprinted polymer-based electrochemical impedimetric sensors on screen-printed carbon electrodes for the detection of trace cytokine IL-1β

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.

Artificial Biomimetic Electrochemical Assemblies

Rapid, selective, and cost-effective detection and determination of clinically relevant biomolecule analytes for a better understanding of biological and physiological functions are becoming increasingly prominent. In this regard, biosensors represent a powerful tool to meet these requirements. Recent decades have seen biosensors gaining popularity due to their ability to design sensor platforms that are selective to determine target analytes. Naturally generated receptor units have a high affinity for their targets, which provides the selectivity of a device. However, such receptors are subject to instability under harsh environmental conditions and have consequently low durability. By applying principles of supramolecular chemistry, molecularly imprinted polymers (MIPs) can successfully replace natural receptors to circumvent these shortcomings. This review summarizes the recent achievements and analytical applications of electrosynthesized MIPs, in particular, for the detection of protein-based biomarkers. The scope of this review also includes the background behind electrochemical readouts and the origin of the gate effect in MIP-based biosensors.

Synthesis of Multifunctional Nanoparticles for the Combination of Photodynamic Therapy and Immunotherapy

Programmed death-ligand 1 protein (PD-L1) has been posited to have a major role in suppressing the immune system during pregnancy, tissue allografts, autoimmune disease and other diseases, such as hepatitis. Photodynamic therapy uses light and a photosensitizer to generate singlet oxygen, which causes cell death (phototoxicity). In this work, photosensitizers (such as merocyanine) were immobilized on the surface of magnetic nanoparticles. One peptide sequence from PD-L1 was used as the template and imprinted onto poly(ethylene-co-vinyl alcohol) to generate magnetic composite nanoparticles for the targeting of PD-L1 on tumor cells. These nanoparticles were characterized using dynamic light scattering, high-performance liquid chromatography, Brunauer-Emmett-Teller analysis and superconducting quantum interference magnetometry. Natural killer-92 cells were added to these composite nanoparticles, which were then incubated with human hepatoma (HepG2) cells and illuminated with visible light for various periods. The viability and apoptosis pathway of HepG2 were examined using a cell counting kit-8 and quantitative real-time polymerase chain reaction. Finally, treatment with composite nanoparticles and irradiation of light was performed using an animal xenograft model.

Epitope recognition of magnetic peptide-imprinted chitosan composite nanoparticles for the extraction of CRISPR/dCas9a proteins from transfected cells

The clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein (Cas9) technology is a powerful method for genetic modification (and regulation) that is of great current interest. The development of new, economical methods of detecting and extracting Cas9 (and/or dCas9) from transfected cells is thus an important advance. In this work, we employed molecular imprinting, using two peptides from the Cas9 protein, to make magnetic peptide-imprinted chitosan nanoparticles. dCas9 was encoded in a plasmid which was then transfected into human embryonic kidney (HEK293T) cells. The expression of dCas9 protein was measured by using total protein kits. Finally, the imprinted nanoparticles were used to extract dCas9 from transfected cell homogenates.

Detection of canine and equine procalcitonin for sepsis diagnosis in veterinary clinic by the development of novel MIP-based SPR biosensors

Procalcitonin (PCT) has emerged as a promising biomarker for the rapid identification of sepsis both in human and veterinary medicine. Nevertheless, the only analytical method currently available for the detection of PCT in veterinary species, is represented by immunoassays, useful only for research purposes. In this work, we report the development of two biosensors which utilize molecularly imprinted polymers (MIPs) for the detection of canine and equine PCT. Dopamine (DA) and norepinephrine (NE) were used as monomers for the synthesis of the MIP films on surface plasmon resonance (SPR) gold chips and the imprinting efficiency of canine and equine PCT in terms of binding affinity toward the analyte, selectivity, and sensitivity were compared. After optimization in buffer conditions, PCTs calibration was successfully achieved also in animal plasma, with good specificity and reproducibility. More effective protein binding and imprinting was obtained with polynorepinephrine (PNE) for both PCTs, and the SPR biosensors were able to detect the biomarkers in plasma with a LOD of 15 ng mL^-1 and 30 ng mL^-1 respectively for equine and canine PCT.

Molecular Imprinting Strategies for Tissue Engineering Applications: A Review

Tissue Engineering (TE) represents a promising solution to fabricate engineered constructs able to restore tissue damage after implantation. In the classic TE approach, biomaterials are used alongside growth factors to create a scaffolding structure that supports cells during the construct maturation. A current challenge in TE is the creation of engineered constructs able to mimic the complex microenvironment found in the natural tissue, so as to promote and guide cell migration, proliferation, and differentiation. In this context, the introduction inside the scaffold of molecularly imprinted polymers (MIPs)—synthetic receptors able to reversibly bind to biomolecules—holds great promise to enhance the scaffold-cell interaction. In this review, we analyze the main strategies that have been used for MIP design and fabrication with a particular focus on biomedical research. Furthermore, to highlight the potential of MIPs for scaffold-based TE, we present recent examples on how MIPs have been used in TE to introduce biophysical cues as well as for drug delivery and sequestering.

Polymeric nanoparticles for selective protein recognition by using thiol-ene miniemulsion photopolymerization

The fabrication of molecularly imprinted nanoparticles (MIP-NPs) specific for myoglobin by using thiol-ene photopolymerization in miniemulsion was described. Allyl derivatives of phenylalanine as a functional monomer was synthesized and copolymerized with acrylic monomers via miniemulsion polymerization to produce NIP-NPs with approximately 74 nm number average particle diameter. FTIR and ¹H-NMR analysis confirmed the synthesis of functional monomer. MIP-NPs were prepared in the existence of myoglobin as a template protein. Morphological investigations exhibited that the particle size of the MIP-NPs, increased compared to the corresponding NIPs and the mean particle diameter by number was measured as 141 nm with narrow distribution. NIP-NPs that were polymerized without myoglobin were found to have less affinity to the target protein. In addition, the rebinding ability of MIP-NPs was much bigger than that of the corresponding NIPs. ELISA results showed that MIPs interact particularly with the myoglobin and show little affinity for BSA in competitive binding experiments.HighlightsAllyl N,N-diallyl phenylalaninate was synthesized as a functional monomer.Imprinted nanoparticles were prepared by using thiol-ene photopolymerization in miniemulsion.The nanoparticles were 141 nm with narrow size distribution.The imprinted nanoparticles showed selectivity toward myoglobin.

How Reliable Is the Electrochemical Readout of MIP Sensors?

Electrochemical methods offer the simple characterization of the synthesis of molecularly imprinted polymers (MIPs) and the readouts of target binding. The binding of electroinactive analytes can be detected indirectly by their modulating effect on the diffusional permeability of a redox marker through thin MIP films. However, this process generates an overall signal, which may include nonspecific interactions with the nonimprinted surface and adsorption at the electrode surface in addition to (specific) binding to the cavities. Redox-active low-molecular-weight targets and metalloproteins enable a more specific direct quantification of their binding to MIPs by measuring the faradaic current. The in situ characterization of enzymes, MIP-based mimics of redox enzymes or enzyme-labeled targets, is based on the indication of an electroactive product. This approach allows the determination of both the activity of the bio(mimetic) catalyst and of the substrate concentration.

Strategies for Molecular Imprinting and the Evolution of MIP Nanoparticles as Plastic Antibodies-Synthesis and Applications

Materials that can mimic the molecular recognition-based functions found in biology are a significant goal for science and technology. Molecular imprinting is a technology that addresses this challenge by providing polymeric materials with antibody-like recognition characteristics. Recently, significant progress has been achieved in solving many of the practical problems traditionally associated with molecularly imprinted polymers (MIPs), such as difficulties with imprinting of proteins, poor compatibility with aqueous environments, template leakage, and the presence of heterogeneous populations of binding sites in the polymers that contribute to high levels of non-specific binding. This success is closely related to the technology-driven shift in MIP research from traditional bulk polymer formats into the nanomaterial domain. The aim of this article is to throw light on recent developments in this field and to present a critical discussion of the current state of molecular imprinting and its potential in real world applications.

Doping of transition metal dichalcogenides in molecularly imprinted conductive polymers for the ultrasensitive determination of 17β-estradiol in eel serum

Molecularly imprinted polymers (MIPs) have been developed to replace antibodies for the recognition of target molecules (such as antigens), and have been integrated into electrochemical sensing approaches by polymerization onto an electrode. Electrochemical sensing is inexpensive and flexible, and has demonstrated utility in point-of-care devices. In this work, several 2D (conductive) materials were employed to improve the performance of MIP sensors. Screen-printed electrodes were coated by the electropolymerization of aniline and metanilic acid, commingled with target molecules and various 2D materials. Tungsten disulfide (WS₂) with an average particle size of 2 μm was found to increase the sensitivity of detection of molecularly imprinted conductive polymer-coated electrodes to 17β-estradiol. As estradiol concentrations are important to eel aquaculture, we screened eel serum samples to determine their 17β-estradiol concentrations, which were found to be in the range 28.2 ± 3.6 to 73.0 ± 11.6 pg/mL after dilution. These results were in agreement with measurements using commercial immunoanalysis.

Immunotherapy of Hepatocellular Carcinoma with Magnetic PD-1 Peptide-Imprinted Polymer Nanocomposite and Natural Killer Cells

Programmed cell death protein 1 (PD-1) is a biomarker on the surface of cells with a role in promoting self-tolerance by suppressing the inflammatory activity of T cells. In this work, one peptide of PD-1 was used as the template for molecular imprinting to form magnetic peptide-imprinted poly(ethylene-co-vinyl alcohol) composite nanoparticles (MPIP NPs). The nanoparticles were characterized by dynamic light scattering (DLS), high-performance liquid chromatography (HPLC), Brunauer–Emmett–Teller (BET) analysis, and superconducting quantum interference device (SQUID) analysis. Natural killer 92 (NK-92) cells were added to these composite nanoparticles and then incubated with human hepatoma (HepG2) cells. The viability and the apoptosis pathway of HepG2 were then studied using cell counting kit-8 (CCK8) and quantitative real-time polymerase chain reaction (qRT-PCR), respectively. These nanoparticles were found to significantly enhance the activity of natural killer cells toward HepG2 cells by increasing the expression of nuclear factor kappa B (NF-κB), caspase 8, and especially caspase 3.

Recent Advances in Electrosynthesized Molecularly Imprinted Polymer Sensing Platforms for Bioanalyte Detection

The accurate detection of biological materials has remained at the forefront of scientific research for decades. This includes the detection of molecules, proteins, and bacteria. Biomimetic sensors look to replicate the sensitive and selective mechanisms that are found in biological systems and incorporate these properties into functional sensing platforms. Molecularly imprinted polymers (MIPs) are synthetic receptors that can form high affinity binding sites complementary to the specific analyte of interest. They utilise the shape, size, and functionality to produce sensitive and selective recognition of target analytes. One route of synthesizing MIPs is through electropolymerization, utilising predominantly constant potential methods or cyclic voltammetry. This methodology allows for the formation of a polymer directly onto the surface of a transducer. The thickness, morphology, and topography of the films can be manipulated specifically for each template. Recently, numerous reviews have been published in the production and sensing applications of MIPs; however, there are few reports on the use of electrosynthesized MIPs (eMIPs). The number of publications and citations utilising eMIPs is increasing each year, with a review produced on the topic in 2012. This review will primarily focus on advancements from 2012 in the use of eMIPs in sensing platforms for the detection of biologically relevant materials, including the development of increased polymer layer dimensions for whole bacteria detection and the use of mixed monomer compositions to increase selectivity toward analytes.

The molecularly imprinted polymer essentials: curation of anticancer, ophthalmic, and projected gene therapy drug delivery systems

The development of polymeric materials as drug delivery systems has advanced from systems that rely on classical passive targeting to carriers that can sustain the precisely controlled release of payloads upon physicochemical triggers in desired microenvironment. Molecularly imprinted polymers (MIP), materials designed to capture specific molecules based on their molecular shape and charge distribution, are attractive candidates for fulfilling these purposes. In particular, drug-imprinted polymers coupled with active targeting mechanisms have been explored as potential drug delivery systems. In this review, we have curated important recent efforts in the development of drug-imprinted polymers in a variety of clinical applications, especially oncology and ophthalmology. MIP possesses properties that may complement the traditional delivery systems of these two disciplines, such as passive enhanced permeability and retention effect (EPR) in cancer tumors, and passive drug diffusion in delivering ophthalmic therapeutics. Furthermore, the prospects of MIP integration with the emerging gene therapies will be discussed.

Plastic antibodies tailored on quantum dots for an optical detection of myoglobin down to the femtomolar range

A highly sensitive fluorescence detection probe was developed by tailoring plastic antibodies on the external surface of aqueous soluble quantum dots (QDs). The target was Myoglobin (Myo), a cardiac biomarker that quenched the intrinsic fluorescent emission of cadmium telluride (CdTe) QDs capped with mercaptopropionic acid (CdTe-MPA-QDs). The QDs were incubated with the target protein and further modified with a molecularly-imprinted polymer (MIP) produced by radical polymerization of acrylamide and bisacrylamide. The main physical features of the materials were assessed by electron microscopy, dynamic light scattering (DLS), UV/Vis spectrophotometry and spectrofluorimetry. The plastic antibodies enabled Myo rebinding into the QDs with subsequent fluorescence quenching. This QD-probe could detect Myo concentrations from 0.304 to 571 pg/ml (50.6 fM to 95 pM), with a limit of detection of 0.045 pg/ml (7.6 fM). The proposed method was applied to the determination of Myo concentrations in synthetic human serum. The results obtained demonstrated the ability of the modified-QDs to determine Myo below the cut-off values of myocardial infarction. Overall, the nanostructured MIP-QDs reported herein displayed quick responses, good stability and sensitivity, and high selectivity for Myo, offering the potential to be explored as new emerging sensors for protein detection in human samples.

Ultrasensitive Detection of Biomarkers by Using a Molecular Imprinting Based Capacitive Biosensor

The ability to detect and quantitate biomolecules in complex solutions has always been highly sought-after within natural science; being used for the detection of biomarkers, contaminants, and other molecules of interest. A commonly used technique for this purpose is the Enzyme-linked Immunosorbent Assay (ELISA), where often one antibody is directed towards a specific target molecule, and a second labeled antibody is used for the detection of the primary antibody, allowing for the absolute quantification of the biomolecule under study. However, the usage of antibodies as recognition elements limits the robustness of the method; as does the need of using labeled molecules. To overcome these limitations, molecular imprinting has been implemented, creating artificial recognition sites complementary to the template molecule, and obsoleting the necessity of using antibodies for initial binding. Further, for even higher sensitivity, the secondary labeled antibody can be replaced by biosensors relying on the capacitance for the quantification of the target molecule. In this protocol, we describe a method to rapidly and label-free detect and quantitate low-abundant biomolecules (proteins and viruses) in complex samples, with a sensitivity that is significantly better than commonly used detection systems such as the ELISA. This is all mediated by molecular imprinting in combination with a capacitance biosensor.

Molecular Imprinting of Macromolecules for Sensor Applications

Molecular recognition has an important role in numerous living systems. One of the most important molecular recognition methods is molecular imprinting, which allows host compounds to recognize and detect several molecules rapidly, sensitively and selectively. Compared to natural systems, molecular imprinting methods have some important features such as low cost, robustness, high recognition ability and long term durability which allows molecularly imprinted polymers to be used in various biotechnological applications, such as chromatography, drug delivery, nanotechnology, and sensor technology. Sensors are important tools because of their ability to figure out a potentially large number of analytical difficulties in various areas with different macromolecular targets. Proteins, enzymes, nucleic acids, antibodies, viruses and cells are defined as macromolecules that have wide range of functions are very important. Thus, macromolecules detection has gained great attention in concerning the improvement in most of the studies. The applications of macromolecule imprinted sensors will have a spacious exploration according to the low cost, high specificity and stability. In this review, macromolecules for molecularly imprinted sensor applications are structured according to the definition of molecular imprinting methods, developments in macromolecular imprinting methods, macromolecular imprinted sensors, and conclusions and future perspectives. This chapter follows the latter strategies and focuses on the applications of macromolecular imprinted sensors. This allows discussion on how sensor strategy is brought to solve the macromolecules imprinting.

Imprinting Technology in Electrochemical Biomimetic Sensors

Biosensors are a promising tool offering the possibility of low cost and fast analytical screening in point-of-care diagnostics and for on-site detection in the field. Most biosensors in routine use ensure their selectivity/specificity by including natural receptors as biorecognition element. These materials are however too expensive and hard to obtain for every biochemical molecule of interest in environmental and clinical practice. Molecularly imprinted polymers have emerged through time as an alternative to natural antibodies in biosensors. In theory, these materials are stable and robust, presenting much higher capacity to resist to harsher conditions of pH, temperature, pressure or organic solvents. In addition, these synthetic materials are much cheaper than their natural counterparts while offering equivalent affinity and sensitivity in the molecular recognition of the target analyte. Imprinting technology and biosensors have met quite recently, relying mostly on electrochemical detection and enabling a direct reading of different analytes, while promoting significant advances in various fields of use. Thus, this review encompasses such developments and describes a general overview for building promising biomimetic materials as biorecognition elements in electrochemical sensors. It includes different molecular imprinting strategies such as the choice of polymer material, imprinting methodology and assembly on the transduction platform. Their interface with the most recent nanostructured supports acting as standard conductive materials within electrochemical biomimetic sensors is pointed out.

Capacitive Biosensors and Molecularly Imprinted Electrodes

Capacitive biosensors belong to the group of affinity biosensors that operate by registering direct binding between the sensor surface and the target molecule. This type of biosensors measures the changes in dielectric properties and/or thickness of the dielectric layer at the electrolyte/electrode interface. Capacitive biosensors have so far been successfully used for detection of proteins, nucleotides, heavy metals, saccharides, small organic molecules and microbial cells. In recent years, the microcontact imprinting method has been used to create very sensitive and selective biorecognition cavities on surfaces of capacitive electrodes. This chapter summarizes the principle and different applications of capacitive biosensors with an emphasis on microcontact imprinting method with its recent capacitive biosensor applications.

Molecular Imprinting Techniques Used for the Preparation of Biosensors

Molecular imprinting is the technology of creating artificial recognition sites in polymeric matrices which are complementary to the template in their size, shape and spatial arrangement of the functional groups. Molecularly imprinted polymers (MIPs) and their incorporation with various transducer platforms are among the most promising approaches for detection of several analytes. There are a variety of molecular imprinting techniques used for the preparation of biomimetic sensors including bulk imprinting, surface imprinting (soft lithography, template immobilization, grafting, emulsion polymerization) and epitope imprinting. This chapter presents an overview of all of these techniques with examples from particular publications.

The potential use of glucose oxidase-imprinted polymer-coated electrodes for biofuel cells

Enzymatic biofuel cells using molecularly imprinted polymer coated electrodes.

Microcontact imprinted quartz crystal microbalance nanosensor for protein C recognition

Detection of protein C (PC) in human serum was performed by quartz crystal microbalance (QCM) based on molecular imprinting technique (MIP). The high-resolution and mass-sensitive QCM based sensor was integrated with high sensitivity and selectivity of the MIP technique. The PC microcontact imprinted (PC-μCIP) nanofilm was prepared on the glass surface. Then, the PC-μCIP/QCM sensor was prepared with 2-hydroxyethyl methacrylate (HEMA), ethylene glycol dimethacrylate (EGDMA) and N-methacryloyl l-histidine methylester (MAH) as the functional monomer with copper(II) ions. The polymerization was performed under UV light (100W and 365nm) for 20-25min under nitrogen atmosphere. The characterization studies of QCM sensor were done by observation using atomic force microscopy (AFM), contact angle measurements, ellipsometry and fourier transform infrared spectroscopy (FTIR). Detection of PC was investigated in a concentration range of 0.1-30μg/mL. Selectivity of PC-μCIP and PC non-imprinted/QCM (PC-non-μCIP) sensors for PC determination was investigated by using proteins namely hemoglobin (Hb), human serum albumin (HSA) and fibrinogen solutions. QCM sensor was also used for detection of PC molecules in aqueous solutions and human plasma. The detection limit was determined as 0.01μg/mL for PC analysis. The PC-μCIP/QCM sensor was used for five consecutive adsorption-desorption cycles. According to the results, the PC-μCIP/QCM sensor had obtained high selectivity and sensitivity for detection of PC molecules.

Molecularly imprinted polymer membranes and thin films for the separation and sensing of biomacromolecules

This review describes recent advances associated with the development of surface imprinting methods for the synthesis of polymeric membranes and thin films, which possess the capability to selectively and specifically recognize biomacromolecules, such as proteins and single- and double-stranded DNA, employing "epitope" or "whole molecule" approaches. Synthetic procedures to create different molecularly imprinted polymer membranes or thin films are discussed, including grafting/in situ polymerization, drop-, dip-, or spin-coating procedures, electropolymerization as well as micro-contact or stamp lithography imprinting methods. Highly sensitive techniques for surface characterization and analyte detection are described, encompassing luminescence and fluorescence spectroscopy, X-ray photoelectron spectroscopy, FTIR spectroscopy, surface-enhanced Raman spectroscopy, atomic force microscopy, quartz crystal microbalance analysis, cyclic voltammetry, and surface plasmon resonance. These developments are providing new avenues to produce bioelectronic sensors and new ways to explore through advanced separation science procedures complex phenomena associated with the origins of biorecognition in nature.

MIPs and Aptamers for Recognition of Proteins in Biomimetic Sensing

Biomimetic binders and catalysts have been generated in order to substitute the biological pendants in separation techniques and bioanalysis. The two major approaches use either "evolution in the test tube" of nucleotides for the preparation of aptamers or total chemical synthesis for molecularly imprinted polymers (MIPs). The reproducible production of aptamers is a clear advantage, whilst the preparation of MIPs typically leads to a population of polymers with different binding sites. The realization of binding sites in the total bulk of the MIPs results in a higher binding capacity, however, on the expense of the accessibility and exchange rate. Furthermore, the readout of the bound analyte is easier for aptamers since the integration of signal generating labels is well established. On the other hand, the overall negative charge of the nucleotides makes aptamers prone to non-specific adsorption of positively charged constituents of the sample and the "biological" degradation of non-modified aptamers and ionic strength-dependent changes of conformation may be challenging in some application.

Electrochemical sensing of nuclear matrix protein 22 in urine with molecularly imprinted poly(ethylene-co-vinyl alcohol) coated zinc oxide nanorod arrays for clinical studies of bladder cancer diagnosis

In 1996 and 2000, the US Food and Drug Administration (FDA) approved the use of Nuclear matrix protein 22 (NMP22) as a monitoring tool for predicting the recurrence/clearing of bladder cancer, and for screening undiagnosed individuals who have symptoms of, or are at risk for, that disease. The fabrication of electrodes for sensing NMP22 and their integration with a portable potentiostat in a homecare system may have great value. This work describes a sensing element comprised of molecularly imprinted polymers (MIPs) for the specific recognition of NMP22 target molecules. Zinc oxide (ZnO) nanorods (214 ± 45 nm in diameter and 1.08 ± 0.11 μm long) were hydrothermally grown on the sensing electrodes to increase the surface area to be coated with MIPs. A portable potentiostat was assembled and a data acquisition (DAQ) card and the Labview program were utilized to monitor electrochemical reaction to sense NMP22 in urine samples. Finally, in phase 0 clinical trials, measurements were made of samples from a few patients with bladder cancer using the NMP22 MIP-coated ZnO nanorods electrodes that were integrated into a portable potentiostat, revealing NMP 22 concentrations in the range 128 ± 19 to 588 ± 53 ng/mL.

Monoclonal antibody capture from cell culture supernatants using epitope imprinted macroporous membranes

A straightforward epitope imprinting procedure is used to prepare IgG affinity membranes directly applicable to mAb capture under near process realistic conditions.

From imprinting to microcontact imprinting-A new tool to increase selectivity in analytical devices

Molecular imprinting technology has been successfully applied to small molecular templates but a slow progress has been made in macromolecular imprinting owing to the challenges in natural properties of macromolecules, especially proteins. In this review, the macromolecular imprinting approaches are discussed with examples from recent publications. A new molecular imprinting strategy, microcontact imprinting is highlighted with its recent applications.

Molecular imprinting science and technology: a survey of the literature for the years 2004-2011

Herein, we present a survey of the literature covering the development of molecular imprinting science and technology over the years 2004-2011. In total, 3779 references to the original papers, reviews, edited volumes and monographs from this period are included, along with recently identified uncited materials from prior to 2004, which were omitted in the first instalment of this series covering the years 1930-2003. In the presentation of the assembled references, a section presenting reviews and monographs covering the area is followed by sections describing fundamental aspects of molecular imprinting including the development of novel polymer formats. Thereafter, literature describing efforts to apply these polymeric materials to a range of application areas is presented. Current trends and areas of rapid development are discussed.

Microcontact imprinting of algae for biofuel systems: the effects of the polymer concentration

Microcontact imprinting of cells often involves the deposition of a polymer solution onto a monolayer cell stamp, followed by solvent evaporation. Thus, the concentration of the polymer may play an important role in the final morphology and efficacy of the imprinted film. In this work, various concentrations of poly(ethylene-co-vinyl alcohol) (EVAL) were dissolved in dimethyl sulfoxide (DMSO) for the microcontact imprinting of algae on an electrode. Scanning electron microscopy and fluorescence spectrometry were used to characterize the surface morphology and recognition capacity of algae to the algae-imprinted cavities. The readsorption of algae onto algae-imprinted EVAL thin films was quantified to obtain the EVAL concentration that maximized algal binding. Finally, the power and current density of an algal biofuel cell with the algae-imprinted EVAL-coated electrode were measured and found to be approximately double those of such a cell with a Pt/indium tin oxide (ITO)/poly(ethylene terephthalate) (PET) electrode.

Microcontact-BSA imprinted capacitive biosensor for real-time, sensitive and selective detection of BSA

An analytical method is presented, combining novel microcontact imprinting technique and capacitive biosensor technology for the detection of BSA. Glass cover slips were used for preparation of protein stamps. The microcontact-BSA imprinted gold electrodes were prepared in the presence of methacrylic acid (MAA) and poly-ethylene glycol dimethacrylate (PEGDMA) as the cross-linker by bringing the protein stamp and the gold electrode into contact under UV-polymerization. Real-time BSA detection studies were performed in the concentration range of 1.0 × 10-20-1.0 × 10-8 M with a limit of detection (LOD) of 1.0 × 10-19 M. Cross-reactivity towards HSA and IgG were 5 and 3%, respectively. The electrodes were used for >70 assays during 2 months and retained their binding properties during all that time. The NIP (non-imprinted) electrode was used as a reference. The microcontact imprinting technology combined with the biosensor applications is a promising technology for future applications.

Hydrogel-Based Molecularly Imprinted Polymers for Biological Detection

Molecularly imprinted polymers (MIPs) have become an important tool in the preparation of artificial and robust recognition materials that are capable of mimicking natural systems. MIPs have been regarded as 'antibody mimics' and have shown clear advantages over real antibodies for sensor technology. Currently, on-site diagnostic (OSD) and point-of-care (POC) biosensor development are heavily dominated by antibody-dependent immuno-sensors such as the lateral flow immuno-assay. Although antibodies exhibit a high degree of selectivity, any biological recognition element is inherently unstable with limited shelf-life, even when stored under optimum conditions. OSD and POC tests are essential for disease screening and treatment monitoring as part of emergency management. Introduced or naturally occurring pathogens can cause significant disruptions, raise panic in the population, and result in significant economic losses. Cheaper, smaller, and smarter devices for early detection of disease or environmental hazards ultimately lead to rapid containment and corrective action. To this end, there has been extensive research on detection platforms based on genetic or immune techniques. MIPs have proven to produce selective biological extractions that rival immunoaffinity-based separations, but without the tediously lengthy time-consuming process. MIPs could provide an alternative to antibodies, and ultimately lead to cheaper, smaller, and smarter biosensors.