Recent Advances of Nanomaterials-Based Molecularly Imprinted Electrochemical Sensors

A molecularly imprinted electrochemical sensor based on in-situ polymerization for rapid and selective detection of tonalide in aqueous environment

Given the adverse effects of tonalide (AHTN) on aquatic organisms and humans, coupled with the limitations of current detection methods, which are time-consuming, require expensive equipment and complicated sample preparation procedures, there is a clear need to develop a new technique for detecting AHTN that is highly sensitive, rapid, cost-effective and efficient. In this study, a new simple electrochemical sensor for the determination of AHTN in aqueous environments was developed for the first time through the in-situ polymerization of an AHTN-imprinted polymer on the surface of a graphene (G)-modified carbon electrode (GCE). Following a series of comparative tests, including cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM), the novel AHTN molecularly imprinted sensor (AHTN-MIP/G/GCE) has been demonstrated to be an effective tool for monitoring AHTN. The results demonstrate that the linear detection range of the current response of the AHTN-MIP/G/GCE 1electrode to AHTN was 0.01 μM-4 μM (i.e., 2.584 μg/L-1033.6 μg/L), with a detection limit of 2.3 × 10⁻⁹ M (i.e., 594.32 ng/L), following the optimization of the experimental conditions. Furthermore, the new sensor was successfully employed for the detection of AHTN in water samples, with recoveries of 97.1%-108.2 % with the added standards. Consequently, the new electrochemical sensor demonstrated good stability and acceptable reproducibility. This study provides a new method for the future detection of AHTN in the aqueous environment.

Electrochemical Sensors in the Food Sector: A Review

In a world that is becoming increasingly concerned with health, safety, and the sustainability of food supply chains, the control and assurance of food quality have become of utmost importance. This review examines the application and potential of electrochemical sensors in the dynamic field of food science to meet these expanding demands. The article introduces electrochemical sensors and describes their operational mechanics and the components contributing to their function. A summary of the most prevalent electrochemical methods outlines the diverse food analysis techniques available. The review shifts to discussing the food science applications of these sensors, highlighting their crucial role in detecting compounds in food samples like meat, fish, juice, and milk for contemporary quality control. This paper showcases electrochemical sensors' utility in food analysis, underscoring their significance as powerful, efficient tools for maintaining food safety and how they could transform our approach to global food quality control and assurance.

Construction of a self-reporting molecularly-imprinted electrochemical sensor based on CuHCF modified by rGNR-rGO for the detection of zearalenone

A self-reporting molecularly-imprinted electrochemical sensor is prepared for the detection of Zearalenone (ZEA). Firstly, the reduced graphene nanoribbons and reduced graphene oxide (rGNR-rGO) were simultaneously modified onto a glassy carbon electrode (GCE) to improve the sensor's sensitivity. After electrodepositing copper nanoparticles onto the rGNR-rGO/GCE, cyclic voltammetry scanning was performed in potassium ferrocyanide solution, and copper hexacyanoferrate (CuHCF) was deposited onto rGNR-rGO/GCE to further improve the sensor's sensitivity while giving it self-reporting capability. Then, molecularly-imprinted polymer films were prepared on the CuHCF/rGNR-rGO/GCE to ensure the selectivity of the sensor. It is found that the linear range of ZEA detection by the constructed sensor is 0.25-500 ng·mL -1, with a detection limit of 0.09 ng·mL -1. This sensor shows the merits of good selectivity, high sensitivity and accurate detection, providing a great possibility for the precise detection of low concentration ZEA in food.

Electrochemical Sensing Systems for the Analysis of Catechol and Hydroquinone in the Aquatic Environments: A Critical Review

Because of their unique physical, chemical, and biological characteristics, conductive nanomaterials have a lot of potential for applications in materials science, energy storage, environmental science, biomedicine, sensors/biosensors, and other fields. Recent breakthroughs in the manufacture of carbon materials, conductive polymers, metals, and metal oxide nanoparticles based electrochemical sensors and biosensors for applications in environmental monitoring by detection of catechol (CC) and hydroquinone (HQ) are presented in this review. To achieve this goal, we first introduced recent works that discuss the effects of phenolic compounds and the need for accurate, inexpensive, and quick monitoring, and then we focused on the use of the most important applications of nanomaterials, such as carbon-based materials, metals, and metal oxides nanoparticles, and conductive polymers, to develop sensors to monitor catechol and hydroquinone. Finally, we identified challenges and limits in the field of sensors and biosensors, as well as possibilities and recommendations for developing the field for better future applications. Meanwhile, electrochemical sensors and biosensors for catechol and hydroquinone measurement and monitoring were highlighted and discussed particularly. This review, we feel, will aid in the promotion of nanomaterials for the development of innovative electrical sensors and nanodevices for environmental monitoring.

Recent Advancements in Molecularly Imprinted Polymers Based Aptasensors: Critical Role of Nanomaterials for the Efficient Food Safety Analysis

Biosensors are being studied extensively for their ability to detect and analyze molecules. There has been a growing interest in combining molecular imprinted polymers (MIPs) and aptamers to create hybrid recognition elements that offer advantages such as target binding, sensitivity, selectivity, and stability. These hybrid elements have been successfully used in identifying a wide range of analytes in food samples. However, the application of MIP-based aptasensors in different sensing approaches is still challenging due to the low conductivity of MIPs-aptamers and limited adsorption capacity of MIPs. To address these limitations, researchers have been exploring the use of nanomaterials (NMs) to design efficient multiple-recognition systems that exploit the synergies between aptamers and MIPs. These hybrid systems can enhance the sensitivity and selectivity of MIP-based aptasensors in quantifying analytical samples. This review provides a comprehensive overview of recent advancements in the field of MIP-based aptasensors. It also introduces technologies that combine MIPs and aptamers to achieve higher sensitivity and selectivity in quantifying analytical samples. The review also highlights potential future trends and practical approaches that can be employed to address the limitations of MIP-based aptasensors, including the use of new NMs, the development of new fabrication techniques, and the integration of MIP-based aptasensors with other analytical tools.

Enhanced molecular recognition with longer chain crosslinkers in molecularly imprinted polymers for an efficient separation of TR active substances

Molecular imprinting technology has been widely studied as a technique to obtain molecular recognition by artificial means. Selecting functional monomers or polymerization conditions plays a key role to optimize molecularly imprinted polymer (MIP) synthesis. To date, there have been few reports well exploiting the effect of crosslinkers. Here, in this study, we synthesized the MIPs using poly(ethyleneglycol) dimethacrylate with different units of ethylene oxide (n = 1 to 23) as crosslinkers to observe the molecular recognition abilities. The MIPs were attached to the surface of mono-dispersed polymer beads. The obtained spherical MIPs and non-imprinted polymers were filled in a column for high performance liquid chromatography. Then the retention selectivity toward TR active substances was evaluated. The result revealed that the recognition ability did not improve regardless of the amount of ethylene oxide. With the crosslinker (n = 9), extremely high retention selectivity was observed, which provides at most around ten times as large imprinting factors in comparison with other MIPs. Interestingly, we obtained the highest recognition ability at around polymerization temperature from the evaluation of the recognition ability toward temperature shift using the MIP (n = 9). In general, hydrogen bonding based on MIPs provides high recognition ability at low temperature, whereas, this study indicates that the use of flexible crosslinkers may enable the synthesis of MIPs that precisely memorize the conditions of polymerization. Lastly, we simultaneously analyzed the TR active substances using the column filled with MIPs (n = 9). The result showed relatively linear correlation between the retention strength of each substance and phycological activity toward TR obtained by yeast assay. Therefore, we can conclude that an induced fit like the receptor emerged by constructing the flexible molecular recognition field.

Research progress of sensors based on molecularly imprinted polymers in analytical and biomedical analysis

Molecularly imprinted polymers (MIPs) have had tremendous impact on biomimetic recognition due to their precise specificity and high affinity comparable to that of antibodies, which has shown the great advantages of easy preparation, good stability and low cost. The combination of MIPs with other analytical technologies can not only achieve rapid extraction and sensitive detection of target compounds, improving the level of analysis, but also achieve precise targeted delivery, in-vivo imaging and other applications. Among them, the recognition mechanism plays a vital role in chemical and biological sensing, while the improvement of the recognition element, such as the addition of new nanomaterials, can greatly improve the analytical performance of the sensor, especially in terms of selectivity. Currently, due to the need for rapid diagnosis and improved sensing properties (such as selectivity, stability, and cost-effectiveness), researchers are investigating new recognition elements and their combinations to improve the recognition capabilities of chemical sensing and bio-sensing. Therefore, this review mainly discusses the design strategies of optical sensors, electrochemical sensors and photoelectric sensors with molecular imprinting technology and their applications in environmental systems, food fields, drug detection and biology including bacteria and viruses.

Development of an MIP based electrochemical sensor for TGF-β1 detection and its application in liquid biopsy

Oral cancer is one of the most common types of cancer in Europe and its large diffusion requires, together with prevention, the development of low-cost and reliable portable platforms for its diagnosis, with features of high selectivity and sensitivity. In this study, the development and characterization of a molecularly imprinted polymer (MIP)-based electrochemical sensor for TGF-β1 detection are reported. The optimized biosensor is a potential tool for the early screening of oral cancer. A biomimetic surface has been obtained by electropolymerization of o-phenylenediamine (o-PD) on platinum electrodes, in the presence of TGF-β1 as a template molecule. MIP synthesis, template removal and TGF-β1 rebinding have been monitored by Differential Pulse Voltammetry (DPV). Atomic Force Microscopy (AFM) has been performed to investigate and characterize the surface morphology and the influence of the washing step on MIP and NIP (non-imprinted polymer as the control) while the thickness of the polymer layer has been measured by Scanning Transmission Electron Microscopy (STEM) analysis. The MIP sensor performance has been tested in both buffer solution and saliva samples with TGF-β1, showing a linear response in the considered range (from 20 ng ml-1 down to 0.5 ng ml-1), an outstanding LOD of 0.09 ng mL-1 and affinity and selectivity to TGF-β1 also in the presence of interfering molecules. The sensor was used also for the detection of target molecules in spiked saliva samples with good recovery results suggesting the possibility of the use of the proposed system for large scale fast screening in oral cancer diagnosis.

Special Issue: Recent Advances in Nanomaterials for Electrochemical Sensing and Nano-Biosensing

Nanomaterials have been instrumental in the development of electrochemical nano-biosensors, offering high sensitivity and selectivity [...].

A Fusion of Molecular Imprinting Technology and Siloxane Chemistry: A Way to Advanced Hybrid Nanomaterials

Molecular imprinting technology is a well-known strategy to synthesize materials with a predetermined specificity. For fifty years, the "classical" approach assumed the creation of "memory sites" in the organic polymer matrix by a template molecule that interacts with the functional monomer prior to the polymerization and template removal. However, the phenomenon of a material's "memory" provided by the "footprint" of the chemical entity was first observed on silica-based materials nearly a century ago. Through the years, molecular imprinting technology has attracted the attention of many scientists. Different forms of molecularly imprinted materials, even on the nanoscale, were elaborated, predominantly using organic polymers to induce the "memory". This field has expanded quickly in recent years, providing versatile tools for the separation or detection of numerous chemical compounds or even macromolecules. In this review, we would like to emphasize the role of the molecular imprinting process in the formation of highly specific siloxane-based nanomaterials. The distinct chemistry of siloxanes provides an opportunity for the facile functionalization of the surfaces of nanomaterials, enabling us to introduce additional properties and providing a way for vast applications such as detectors or separators. It also allows for catalyzing chemical reactions providing microreactors to facilitate organic synthesis. Finally, it determines the properties of siloxanes such as biocompatibility, which opens the way to applications in drug delivery and nanomedicine. Thus, a brief outlook on the chemistry of siloxanes prior to the discussion of the current state of the art of siloxane-based imprinted nanomaterials will be provided. Those aspects will be presented in the context of practical applications in various areas of chemistry and medicine. Finally, a brief outlook of future perspectives for the field will be pointed out.

Electrochemical Detection of Olivetol Based on Poly(L-Serine) Film Layered Copper Oxide Modified Carbon Paste Electrode (p-L-Serine/CuO/CPE)

Olivetol is an important polyphenol compound and intermediate in the synthesis of cannabinoids possessing many types of biological activities. A facile electrochemical sensor for olivetol was fabricated based on p-L-serine, and copper oxide (CuO) nanoparticles modified carbon paste electrode (p-L-serine/CuO/CPE). The proposed p-L-serine/CuO/CPE was applied to the electrochemical detection of olivetol by cyclic voltammetry (CV) and differential pulse voltammetric (DPV). Through the characterizations of materials and modified electrodes, the p-L-serine/CuO/CPE exhibited enhanced electrochemical signals for olivetol compared to bare CPE and CuO/CPE in both CV and DPV methods. Under the optimized conditions, the proposed p-L-serine/CuO/CPE showed a good quantitative analysis ability and a wide analysis range from 20 to 100 μmol L^-1 of olivetol with a limit of detection of 1.04 μmol L^-1. Based on the reproducibility, repeatability, and stability exhibited by this fabricated sensor and the cheap and accessible raw materials, the p-L-serine/CuO/CPE became a novel determination choice for olivetol in the electrochemical method with the advantages of being cost-effective and convenient.