The creation of selective imprinted cavities on quartz crystal microbalance electrode for the detection of melamine in milk sample

A sensitive fluorescent assay based on gold-nanoclusters coated on molecularly imprinted covalent organic frameworks and its application in malachite green detection

Malachite green (MG), as a parasiticide, is widely used in aquaculture to increase the production of the fishery industry. It poses a great danger to both the food system and the human body. In this study, a one-pot reverse microemulsion polymerization was employed to combine the gold nanoclusters (AuNCs) with molecularly imprinted polymers (MIPs) and covalent organic frameworks (COFs) to synthesize an efficient fluorescent hybrid probe (AuNCs@COFs@MIPs) for selective detection of MG. The specific recognition of AuNCs@COFs@MIPs towards MG triggers the fluorescence quenching of AuNCs. The fluorescent response was linearly related to the concentration over the range of 10-150 nmol/L with a limit of detection of 2.78 nmol/L. In addition, the proposed probe was further applied to fish and water samples. A favorable recovery ranged from 97.34 to 101.51 % toward trace amounts of MG indicating its promising application for detecting residue of veterinary drugs.

Designing of ZnO nanoparticles oriented interface imprinted electrochemical sensor for fluoxetine detection

This study represents nanoparticle-based well-oriented recognition sites via interface imprinting, followed by selective and sensitive determination of fluoxetine (FLX). Herein, FLX was firstly immobilized onto ZnO NPs, and then polymerization was carried out with MAPA, HEMA, and EGDMA on the glassy carbon electrode via photopolymerization. After the etching of ZnO with and 10 mM HCI solution, a porous structure with recognition sites for FLX was constructed onto surface. The characterization of the electrochemical sensor was accomplished by utilizing CV, EIS, ATR-FTIR AFM, and SEM analysis. The DPV was used to determine FLX in standard solution, serum sample, and tap water. The effect of FLX concentration variation was studied using the DPV in the range of 1.0 × 10^-11 M to 1.0 × 10^-10 M with a detection limit of 2.67 × 10^-12 M. This sensor showed specific recognition toward template, and more than 90% of its original response was retained after being stored in the desiccator at R.T. for 5 days. This technique has proven to be a powerful, highly selective, and sensitive tool for the rapid detection of FLX in tap water and spike serum samples.

An advantageous application of molecularly imprinted polymers in food processing and quality control

In the global market era, food product control is very challenging. It is impossible to track and control all production and delivery chains not only for regular customers but also for the State Sanitary Inspections. Certified laboratories currently use accurate food safety and quality inspection methods. However, these methods are very laborious and costly. The present review highlights the need to develop fast, robust, and cost-effective analytical assays to determine food contamination. Application of the molecularly imprinted polymers (MIPs) as selective recognition units for chemosensors' fabrication was herein explored. MIPs enable fast and inexpensive electrochemical and optical transduction, significantly improving detectability, sensitivity, and selectivity. MIPs compromise durability of synthetic materials with a high affinity to target analytes and selectivity of molecular recognition. Imprinted molecular cavities, present in MIPs structure, are complementary to the target analyte molecules in terms of size, shape, and location of recognizing sites. They perfectly mimic natural molecular recognition. The present review article critically covers MIPs' applications in selective assays for a wide range of food products. Moreover, numerous potential applications of MIPs in the food industry, including sample pretreatment before analysis, removal of contaminants, or extraction of high-value ingredients, are discussed.

A Molecularly Imprinted Polymer-Based Thermal Sensor for the Selective Detection of Melamine in Milk Samples

In recent years, melamine-sensing technologies have increasingly gained attention, mainly due to the misuse of the molecule as an adulterant in milk and other foods. Molecularly imprinted polymers (MIPs) are ideal candidates for the recognition of melamine in real-life samples. The prepared MIP particles were incorporated into a thermally conductive layer via micro-contact deposition and its response towards melamine was analyzed using the heat-transfer method (HTM). The sensor displayed an excellent selectivity when analyzing the thermal response to other chemicals commonly found in foods, and its applicability in food safety was demonstrated after evaluation in untreated milk samples, demonstrating a limit of detection of 6.02 μM. As the EU/US melamine legal limit in milk of 2.5 mg/kg falls within the linear range of the sensor, it can offer an innovative solution for routine screening of milk samples in order to detect adulteration with melamine. The results shown in this work thus demonstrate the great potential of a low-cost thermal platform for the detection of food adulteration in complex matrices.

Bulk and Surface Acoustic Wave Biosensors for Milk Analysis

Milk and dairy products are common foods and, therefore, are subject to regular controls. Such controls cover both the identification and quantification of specific components and the determination of physical parameters. Components include the usual milk ingredients, mainly carbohydrates, proteins, and fat, and any impurities that may be present. The latter range from small molecules, such as drug residues, to large molecules, e.g., protein-based toxins, to pathogenic microorganisms. Physical parameters of interest include viscosity as an indicator of milk gelation. Bulk and surface acoustic wave sensors, such as quartz crystal microbalance (QCM) and surface acoustic wave (SAW) devices, can principally be used for both types of analysis, with the actual application mainly depending on the device coating and the test format. This review summarizes the achievements of acoustic sensor devices used for milk analysis applications, including the determination of physical liquid parameters and the detection of low- and high-molecular-weight analytes and microorganisms. It is shown how the various requirements resulting from the respective analytes and the complex sample matrix are addressed, and to what extent the analytical demands, e.g., with regard to legal limits, are met.

Recent Advances in Quartz Crystal Microbalance Biosensors Based on the Molecular Imprinting Technique for Disease-Related Biomarkers

The molecular imprinting technique is a quickly developing field of interest regarding the synthesis of artificial recognition elements that enable the specific determination of target molecule/analyte from a matrix. Recently, these smart materials can be successfully applied to biomolecule detection in biomimetic biosensors. These biosensors contain a biorecognition element (a bioreceptor) and a transducer, like their biosensor analogs. Here, the basic difference is that molecular imprinting-based biosensors use a synthetic recognition element. Molecular imprinting polymers used as the artificial recognition elements in biosensor platforms are complementary in shape, size, specific binding sites, and functionality to their template analytes. Recent progress in biomolecular recognition has supplied extra diagnostic and treatment methods for various diseases. Cost-effective, more robust, and high-throughput assays are needed for monitoring biomarkers in clinical settings. Quartz crystal microbalance (QCM) biosensors are promising tools for the real-time and quick detection of biomolecules in the past two decades A quick, simple-to-use, and cheap biomarkers detection technology based on biosensors has been developed. This critical review presents current applications in molecular imprinting-based quartz crystal microbalance biosensors for the quantification of biomarkers for disease monitoring and diagnostic results.