Label-free electrochemical multi-sites recognition of G-rich DNA using multi-walled carbon nanotubes–supported molecularly imprinted polymer with guanine sites of DNA

Recent advances in molecularly imprinted polymer-based electrochemical sensors

Molecularly imprinted polymers (MIPs) are the equivalent of natural antibodies and have been widely used as synthetic receptors for the detection of disease biomarkers. Benefiting from their excellent chemical and physical stability, low-cost, relative ease of production, reusability, and high selectivity, MIP-based electrochemical sensors have attracted great interest in disease diagnosis and demonstrated superiority over other biosensing techniques. Here we compare various types of MIP-based electrochemical sensors with different working principles. We then evaluate the state-of-the-art achievements of the MIP-based electrochemical sensors for the detection of different biomarkers, including nucleic acids, proteins, saccharides, lipids, and other small molecules. The limitations, which prevent its successful translation into practical clinical settings, are outlined together with the potential solutions. At the end, we share our vision of the evolution of MIP-based electrochemical sensors with an outlook on the future of this promising biosensing technology.

Development of a molecularly imprinted polymer on silanized graphene oxide for the detection of 17-estradiol in wastewater

This research article demonstrates the synthesis, characterization, and electrochemical evaluation of a molecularly imprinted polymer (MIP) on the surface of silanized graphene oxide (silanized GO), which is nanostructured and used to quantify 17-estradiol (E2) in wastewater. As characterization methods, X-ray diffraction (XRD), Raman spectroscopy, dynamic scattering light (DSL), scanning electron microscope (SEM), and Fourier transform infrared spectroscopy (FTIR) were utilized to examine the synthesized GO, silanized GO, MIP-GO composite, and non-imprinted polymer (NIP)-GO (NIP-GO) composite. FTIR results confirmed the successful synthesis of GO composites. Raman study confirmed the synthesis of monolayer silanized GO, MIP-GO composite, and NIP-GO composite. Surface morphology revealed that after polymerization, the surface of silanized GO sheet-like morphology is covered with nanoparticles. Adsorption kinetics studies revealed that adsorption follows the pseudo-second-order kinetics. Further, we studied the performance of a MIP-GO-based sensor by optimizing the effects of pH, scan rate, and incubation period. The linear calibration was achieved between the oxidation peak current and E2 concentration from 0.1 to 0.81 ppm, with a detection limit of 0.037 ppm. The selectivity of the MIP-GO composite was also checked by using other estrogens, and it was found that E2 is 3.3, 0.5, and 1.4 times more selective than equilin, estriol, and estrone, respectively. The composite was successfully applied to the wastewater samples for the detection of E2, and a good percentage of recoveries were achieved. It suggests that the reported composite can be applied to real samples. PRACTITIONER POINTS: An innovative electrochemical sensor was developed for selective detection of 17-estradiol through molecularly imprinted polymer fabricated on the surface of silanized GO (MIP-GO composite). The developed method was comprehensively validated and found to be linear in the range of 0.1 to 0.8 ppm of 17-estradiol, with 0.037 ppm of limit of detection and 0.1 ppm of limit of quantification, respectively. The developed MIP-GO-composite-based electrochemical sensor was found 3.3, 0.5, and 1.4 times more selective for 17-estradiol than equiline, estriol, and estrone, respectively. The applicability of a developed sensor was also checked on wastewater samples, and a good percent recovery was obtained.

A dual-functional module cellular electrochemical sensing platform for simultaneous detection guanine and xanthine

The separation of the superimposed electrochemical signals of intracellular guanine (G) and xanthine (X) is difficult, which is great obstacle to the application of cell electrochemistry. In this paper, independent functional modules, G-functional module (G-FM) and X-functional module (X-FM), were constructed by molecular imprinting technology for sensitive detection of G and X without mutual interference, then integrated in dual-functional module cellular electrochemical sensing platform (DMCEP) as signal sensing units. DMCEP transmitted signals of G and X in cells synchronously to two windows by two signal sensing channels, and achieved the separation of superimposed signals of G and X in cells. DMCEP exhibited satisfactory reproducibility with relative standard deviation (RSD) of 3.10 and 2.22 %, repeatability with RSD of 3.72 and 3.05 % for G and X detection, and detection limit 0.05 μΜ for G and 0.06 μΜ for X. Good linear relationships between cell concentrations and the signals of G and X on DMCEP were shown in range of 0.75-85 × 10⁶ and 3-85 × 10⁶ cells/mL, respectively. The growth of MCF-7 cells was tracked by DMCEP, and showed consistent trend with the cell counting method, while the change of cell viability from lag to logarithmic phase captured by DMCEP was earlier than that of cell counting method. This strategy provided the foundation for the establishment of the cell viability electrochemical detection method, and new insights into the simultaneous recording of other analyses with superimposed peak positions and the simultaneous tracking of multiple biomarkers.

Rationally designed molecularly imprinted polymer membranes as antibody and enzyme mimics in analytical biotechnology

The paper is a self-review of works on development of new approaches to formation of mimics of receptor and catalytic sites of biological macromolecules in the structure of highly cross-linked polymer membranes and thin films. The general strategy for formation of the binding sites in molecularly imprinted polymer (MIP) membranes and thin films was described. A selective recognition of a number of food toxins, endocrine disruptors and metabolites is based on the results of computational modeling data for the prediction and optimization of their structure. A strategy proposed for the design of the artificial binding sites in MIP membranes was supported by the research performed by the authors on development of a number of the MIP membrane-based affinity and catalytic biosensors for selective and sensitive measurement (detection limits 0.3-100 nM) of the target analytes. Novel versatile approaches aimed at improving sensitivity of the developed biosensor systems were discussed.

Adenine imprinted beads as a novel selective extracellular DNA extraction method reveals underestimated prevalence of extracellular antibiotic resistance genes in various environments

Despite severe threats of extracellular antibiotic resistance genes (eARGs) towards public health in various environments, advanced studies have been hindered mainly by ineffective extracellular DNA (exDNA) extraction methods, which is challenged by trace levels of exDNA and inference from abundant coexisting compounds. This study developed a highly selective exDNA extraction method based on molecular imprinting technology (MIT) by using adenine as the template for the first time. Results suggested that adenine imprinted beads were rough spheres at an average size of 0.39 ± 0.07 μm. They effectively adsorbed DNA in the absence of chaotropic agents, with superior capacity (796.2 mg/g), rate (0.0066/s) and regarding DNA of variable lengths, even the ultra-short DNA (<100 bp). They were also highly selective towards DNA, circumventing the interference of competitive compounds' interference. These properties contribute to efficient exDNA extraction (71 %-119 %) from various environmental samples. Specifically, adenine imprinted beads enabled significantly higher extraction rates of eARGs from river, air and vegetable samples (69 %-95 %) compared to that by commercial DNA extraction products (16 %-62 %). The adenine imprinted beads-based method reveals underestimated eARG levels in the environment and the corresponding risks, and thus will thus be a powerful tool for advanced exDNA research.

Fabrication of an imprinted polymer based graphene oxide composite for label-free electrochemical sensing of Sus DNA

An innovative label-free electrochemical sensor was developed for selective detection of Sus (pig) Deoxyribonucleic acid (DNA) through adenine imprinted polypyrrole fabricated on the surface of allyl mercaptan modified GO (MIP/mGO).

Molecularly imprinted polymers-based DNA biosensors

In multiple biological processes, molecular recognition performs an integral role in detecting bio analytes. Molecular imprinted polymers (MIPs) are tailored sensing materials that can biomimic the biologic ligands and can detect specific target molecules selectively and sensitively. The formulation of molecularly imprinted polymers is followed by the formulation of a control termed as non-imprinted polymer (NIP), which, in the absence of a template, is commonly formulated to evaluate whether distinctive imprints have been produced for the template. Given the difficulties confronting bioanalytical researchers, it is inevitable that this strategy would come out as a central route of multidisciplinary studies to create extremely promising stable artificial receptors as a replacement or accelerate biological matrices. The ease of synthesis, low cost, capability to 'tailor' recognition element for analyte molecules, and stability under harsh environments make MIPs promising candidates as a recognition tool for biosensing. Compared to biological systems, molecular imprinting techniques have several advantages, including high recognition ability, long-term durability, low cost, and robustness, allowing molecularly imprinted polymers to be employed in drug delivery, biosensor technology, and nanotechnology. Molecular imprinted polymer-based sensors still have certain shortcomings in determining biomacromolecules (nucleic acid, protein, lipids, and carbohydrates), considering the vast volume of the latest literature on biomicromolecules. These potential materials are still required to address a few weaknesses until gaining their position in recognition of biomacromolecules. This review aims to highlight the current progress in molecularly imprinted polymers (MIPs)-based sensors for the determination of deoxyribonucleic acid (DNA) or nucleobases.

Selective Adsorption and Photocatalytic Degradation of Extracellular Antibiotic Resistance Genes by Molecularly-Imprinted Graphitic Carbon Nitride

There is a growing need to mitigate the discharge of extracellular antibiotic resistance genes (ARGs) from municipal wastewater treatment systems. Here, molecularly-imprinted graphitic carbon nitride (MIP-C₃N₄) nanosheets were synthesized for selective photocatalytic degradation of a plasmid-encoded ARG (bla_NDM-1, coding for multidrug resistance New Delhi metallo-β-lactamase-1) in secondary effluent. Molecular imprinting with guanine enhanced ARG adsorption, which improved the utilization of photogenerated oxidizing species to degrade bla_NDM-1 rather than being scavenged by background nontarget constituents. Consequently, photocatalytic removal of bla_NDM-1 in secondary effluent with MIP-C₃N₄ (k = 0.111 ± 0.028 min^-1) was 37 times faster than with bare graphitic carbon nitride (k = 0.003 ± 0.001 min^-1) under UVA irradiation (365 nm, 3.64 × 10^-6 Einstein/L·s). MIP-C₃N₄ can efficiently catalyze the fragmentation of bla_NDM-1, which decreased the potential for ARG repair by transformed bacteria. Molecular imprinting also changed the primary degradation pathway; electron holes (h⁺) were the predominant oxidizing species responsible for bla_NDM-1 removal with MIP-C₃N₄ versus free radicals (i.e., ·OH and O₂^-) for coated but nonimprinted C₃N₄. Overall, MIP-C₃N₄ efficiently removed bla_NDM-1 from secondary effluent, demonstrating the potential for molecular imprinting to enhance the selectivity and efficacy of photocatalytic processes to mitigate dissemination of antibiotic resistance from sewage treatment systems.

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.