Nanohybrid electrochemical enzyme sensor for xanthine determination in fish samples

[Research advances in non-immobilized aptamer screening techniques for small-molecule targets]

Aptamers obtained through systematic evolution of ligands by exponential enrichment (SELEX) techniques are single stranded deoxyribonucleic acid (ssDNA) or RNA molecules capable of specifically recognizing target molecules. Such aptamers are easily chemically synthesized and modified, highly thermally stable, and are low toxicity and low immunogenicity. Aptamers that target small molecules have broad applications prospects for the development of new drugs, treating tumors, diagnosing diseases, monitoring environmental pollution, detecting drugs, and in ultrafast and sensitive detection applications. However, the simple structures and low molecular masses of small molecules, along with the limited number of binding groups available for interacting with nucleic acids lead to unstable aptamer-small molecule binding, which poses significant challenges for aptamer screening and sensor development. Efficient screening techniques are crucial for identifying aptamers with excellent performance characteristics. At present, the aptamer screening techniques suitable for small-molecule targets are mainly divided into three categories: target-immobilized-based screening technique, nucleic acid library-immobilized-based screening technique, and target-non-immobilized screening technique. Among them, target-non-immobilized screening technique require fewer screening rounds and result in aptamers with superior (typically nmol/L level) affinities. This paper summarized non-immobilized aptamer screening techniques for small-molecule targets, including principle, advantages, disadvantages and application progress associated with graphene oxide (GO)-SELEX, capillary electrophoresis (CE)-SELEX, and gold nanoparticle-assisted (GNP)-SELEX techniques. In addition, strategies for selecting control targets in aptamer-specific evaluation were summarized.

Applications of chemically modified screen-printed electrodes in food analysis and quality monitoring: a review

Food analysis and food quality monitoring are vital aspects of the food industry, ensuring the safety and authenticity of various food products, from packaged goods to fast food. In this comprehensive review, we explore the applications of chemically modified Screen-Printed Electrodes (SPEs) in these critical domains. SPEs have become extremely useful devices for ensuring food safety and quality assessment because of their adaptability, affordability, and convenience of use. The Introduction opens the evaluation, that covers a wide spectrum of foods, encompassing packaged, junk food, and food quality concerns. This sets the stage for a detailed exploration of chemically modified SPEs, including their nature, types, utilization, and the advantages they offer in the context of food analysis. Subsequently, the review delves into the multitude applications of SPEs in food analysis, ranging from the detection of microorganisms such as bacteria and fungi, which are significant indicators of food spoilage and safety, to the identification of pesticide residues, food colorants, chemicals, toxins, and antibiotics. Furthermore, chemically modified SPEs have proven to be invaluable in the quantification of metal ions and vitamins in various food matrices, shedding light on nutritional content and quality.

Unveiling Xanthine Presence in Rohu Fish Using Ag+-Doped MoS2 Nanosheets Through Electrochemical Analysis

Here, we envisage the development of the rapid, reliable, and facile electrochemical sensor for the primary detection of xanthine (Xn) which is significant for the food quality measurement, based on the silver-doped molybdenum disulfide (Ag@MoS2) nanosheets. The structural and compositional properties of the prepared samples were tested through X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, and X-ray photon spectroscopy (XPS). The two-dimensional (2D) MoS2 nanosheets provide the large surface area for the sensing applications and the silver ions help in the enhanced electrochemical response. The fabricated enzymatic biosensor exhibits magnificent cyclic stability with a limit of detection of 27 nM. Also, the sensor was tested for rapid, reproducible, specific, and regenerable up to 10 cycles and has a shelf life of 2 weeks. The outcomes of this study suggest that the proposed matrix could be employed for the fabrication of devices for early detection of xanthine.

Advances in xanthine biosensors and sensors: A review

Xanthine is derived from hypoxanthine by xanthine oxidase (XOD), a flavoprotein containing molybdenum and non-haem iron, sulfur and from guanine by guanine deaminase enzyme. Xanthine is oxidized into uric acid by XOD. Xanthine is used as an indicator of fish freshness, based on the reactions in which ATP is degraded into xanthine and its quantity increases with time of fish death. Fresh fish meat is required in food industry for making high quality items. The determination of xanthine in biological fluids is also used in diagnosing and curing many diseases like renal failure, gout, xanthinuria, hyperuricemia. Various methods are available for detection of xanthine but most of them are complicated, time consuming less sensitive & specific and require expensive instrumental setup and trained person to operate. Enzyme based biosensors and non enzymic sensors overcome these disadvantages, as these are simple, rapid, specific, sensitive and easy to operate. Present review describes xanthine biosensors, which work optimally between pH 3.5-9.0, temperature 25 °C-65 °C, xanthine concentration ranging from 0.001-50 × 104 µM. These biosensors have also been used to measure xanthine concentration in beverages, urine and serum samples. Various modified electrodes have been discussed for the detection of xanthine using both enzymatic and non-enzymatic approaches in the present review.

Recent Advances in Electrochemical Enzyme-Based Biosensors for Food and Beverage Analysis

Food analysis and control are crucial aspects in food research and production in order to ensure quality and safety of food products. Electrochemical biosensors based on enzymes as the bioreceptors are emerging as promising tools for food analysis because of their high selectivity and sensitivity, short analysis time, and high-cost effectiveness in comparison to conventional methods. This review provides the readers with an overview of various electrochemical enzyme-based biosensors in food analysis, focusing on enzymes used for different applications in the analysis of sugars, alcohols, amino acids and amines, and organic acids, as well as mycotoxins and chemical contaminants. In addition, strategies to improve the performance of enzyme-based biosensors that have been reported over the last five years will be discussed. The challenges and future outlooks for the food sector are also presented.

Novel Enzymatic Biosensor Utilizing a MoS2/MoO3 Nanohybrid for the Electrochemical Detection of Xanthine in Fish Meat

A rapid, reliable, and user-friendly electrochemical sensor was developed for the detection of xanthine (Xn), an important biomarker of food quality. The developed sensor is based on a nanocomposite comprised of molybdenum disulfide-molybdenum trioxide (MoS2/MoO3) and synthesized using a single-pot hydrothermal method. Structural analysis of the MoS2/MoO3 nanocomposite was conducted using X-ray diffraction (XRD) and Raman spectroscopy, while its compositional properties were evaluated through X-ray photoelectron spectroscopy (XPS). Morphological features were observed using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Two-dimensional (2D) MoS2 offers advantages such as a high surface-to-volume ratio, biocompatibility, and strong light-matter interaction, whereas MoO3 serves as an effective electron transfer mediator and exhibits excellent stability in aqueous environments. The enzymatic biosensor derived from this nanocomposite demonstrates remarkable cyclic stability and a low limit of detection of 64 nM. It enables rapid, reproducible, specific, and reproducible detection over 10 cycles while maintaining a shelf life of more than 5 weeks. These findings highlight the potential of our proposed approach for the development of early detection devices for Xn.

Assessing Meat Freshness via Nanotechnology Biosensors: Is the World Prepared for Lightning-Fast Pace Methods?

In the rapidly evolving field of food science, nanotechnology-based biosensors are one of the most intriguing techniques for tracking meat freshness. Purine derivatives, especially hypoxanthine and xanthine, are important signs of food going bad, especially in meat and meat products. This article compares the analytical performance parameters of traditional biosensor techniques and nanotechnology-based biosensor techniques that can be used to find purine derivatives in meat samples. In the introduction, we discussed the significance of purine metabolisms as analytes in the field of food science. Traditional methods of analysis and biosensors based on nanotechnology were also briefly explained. A comprehensive section of conventional and nanotechnology-based biosensing techniques is covered in detail, along with their analytical performance parameters (selectivity, sensitivity, linearity, and detection limit) in meat samples. Furthermore, the comparison of the methods above was thoroughly explained. In the last part, the pros and cons of the methods and the future of the nanotechnology-based biosensors that have been created are discussed.

Engineered nanomaterials-based sensing systems for assessing the freshness of meat and aquatic products: A state-of-the-art review

Meat and aquatic products are susceptible to spoilage during distribution, transportation, and storage, increasing the urgency of freshness evaluation. Engineered nanomaterials (ENMs) typically with the diameter in the range of 1-100 nm exhibit fascinating physicochemical properties. ENMs-based sensing systems have received extensive attention for food freshness assessment due to the advantages of being fast, simple, and sensitive. This review focuses on summarizing the recent application of ENMs-based sensing systems for food freshness detection. First, chemical indicators related to the freshness of meat and aquatic products are described. Then, how to apply the ENMs including noble metal nanomaterials, metal oxide nanomaterials, carbon nanomaterials, and metal-organic frameworks for the construction of different sensing systems were described. Besides, the recent advance in ENMs-based colorimetric, fluorescent, electrochemical, and surface-enhanced Raman spectroscopy sensing systems for assessing the freshness of meat and aquatic products were outlined. Finally, the challenges and future research perspectives for the application of ENMs-based sensing systems were discussed. The ENMs-based sensing systems have been demonstrated as effective tools for freshness evaluation. The sensing performance of ENMs employed in different sensing systems depends on their composition, size, shape, and stability of nanoparticles. For the real application of ENMs in food industries, the risks and regulatory issues associated with nanomaterials need to be further considered. With the continuous development of nanomaterials and sensing devices, the ENMs-based sensors are expected to be applied in-field for rapid detection of the freshness of meat and aquatic products in the future.

Electrochemical immunosensor for the detection of colistin in chicken liver

An innovative amperometric immunosensor has been developed to detect antibiotic colistin from the chicken liver. Colistin is a antibacterial peptide that has been barred for human consumption, but it is being commonly used as a veterinary drug, and as a feed additive for livestock. In the present work, an immunosensor was developed by immobilizing an anti-colistin Ab onto the CNF/AuNPs surface of the screen-printed electrode. The sensor records electrochemical response in the chicken liver spiked with colistin with CV. Additionally, the characterization of electrode surface was done with FE-SEM, FTIR, and EIS at each step of fabrication. The lower LOD was 0.89 μgKg-1, with a R 2 of 0.901 using CV. Further validation of the immunosensor was conducted using commercial chicken liver samples, by comparing the results to those obtained using traditional methods. The fabricated immunosensor showed high specificity towards colistin, which remained stable for 6 months but with a 13% loss in the initial CV current.