Current research progress of mammalian cell-based biosensors on the detection of foodborne pathogens and toxins

Electrochemical biosensors for pathogenic microorganisms detection based on recognition elements

The worldwide spread of pathogenic microorganisms poses a significant risk to human health. Electrochemical biosensors have emerged as dependable analytical tools for the point-of-care detection of pathogens and can effectively compensate for the limitations of conventional techniques. Real-time analysis, high throughput, portability, and rapidity make them pioneering tools for on-site detection of pathogens. Herein, this work comprehensively reviews the recent advances in electrochemical biosensors for pathogen detection, focusing on those based on the classification of recognition elements, and summarizes their principles, current challenges, and prospects. This review was conducted by a systematic search of PubMed and Web of Science databases to obtain relevant literature and construct a basic framework. A total of 171 publications were included after online screening and data extraction to obtain information of the research advances in electrochemical biosensors for pathogen detection. According to the findings, the research of electrochemical biosensors in pathogen detection has been increasing yearly in the past 3 years, which has a broad development prospect, but most of the biosensors have performance or economic limitations and are still in the primary stage. Therefore, significant research and funding are required to fuel the rapid development of electrochemical biosensors. The overview comprehensively evaluates the recent advances in different types of electrochemical biosensors utilized in pathogen detection, with a view to providing insights into future research directions in biosensors.

Nanotechnology-based analytical techniques for the detection of contaminants in aquatic products

Food safety of aquatic products has attracted considerable attention worldwide. Although a series of conventional bioassays and instrumental methods have been developed for the detection of pathogenic bacteria, heavy metal residues, marine toxins, and biogenic amines during the production and storage of fish, shrimp, crabs et al., the nanotechnology-based analyses still have their advantages and are promising since they are cost-efficient, highly sensitive and selective, easy to conduct, facial design, often require no sophisticated instruments but with excellent detection performance. This review aims to summarize the advances of various biosensing strategies for bacteria, metal ions, and small molecule contaminants in aquatic products during the last five years, The review highlights the development in nanotechnologies applied for biorecognition process, signal transduction and amplification methods in each novel approach, the nuclease-mediated DNA amplification, nanomaterials (noble metal nanoparticle, metal-organic frameworks, carbon dots), lateral flow-based biosensor, surface-enhanced Raman scattering, microfluidic chip, and molecular imprinting technologies were especially emphasized. Moreover, this study provides a view of current accomplishments, challenges, and future development directions of nanotechnology in aquatic product safety evaluation.

A novel 3D bio-printing “liver lobule” microtissue biosensor for the detection of AFB1

In this paper, a novel "liver lobule" microtissue biosensor based on 3D bio-printing is developed to rapidly determine aflatoxin B₁ (AFB₁). Methylacylated Hyaluronic acid (HAMA) hydrogel, HepG2 cells, and carbon nanotubes are used to construct "liver lobule" models. In addition, 3D bio-printing is used to perform high-throughput and standardized preparation in order to simulate the organ morphology and induce functional formation. Afterwards, based on the electrochemical rapid detection technology, a 3D bio-printed "liver lobule" microtissue is immobilized on the screen-printed electrode, and the mycotoxin is detected by differential pulse voltammetry (DPV). The DPV response increases with the concentration of AFB₁ in the range of 0.1-3.5 μg/mL. The linear detection range is 0.1-1.5 μg/mL and the calculated lowest detection limit is 0.039 μg/mL. Thus, this study develops a new mycotoxin detection method based on the 3D printing technology, which has high stability and reproducibility. It has wide application prospects in the field of detection and evaluation of food hazards.

Label-Free Electrochemical Biosensor Platforms for Cancer Diagnosis: Recent Achievements and Challenges

With its fatal effects, cancer is still one of the most important diseases of today's world. The underlying fact behind this scenario is most probably due to its late diagnosis. That is why the necessity for the detection of different cancer types is obvious. Cancer studies including cancer diagnosis and therapy have been one of the most laborious tasks. Since its early detection significantly affects the following therapy steps, cancer diagnosis is very important. Despite researchers' best efforts, the accurate and rapid diagnosis of cancer is still challenging and difficult to investigate. It is known that electrochemical techniques have been successfully adapted into the cancer diagnosis field. Electrochemical sensor platforms that are brought together with the excellent selectivity of biosensing elements, such as nucleic acids, aptamers or antibodies, have put forth very successful outputs. One of the remarkable achievements of these biomolecule-attached sensors is their lack of need for additional labeling steps, which bring extra burdens such as interference effects or demanding modification protocols. In this review, we aim to outline label-free cancer diagnosis platforms that use electrochemical methods to acquire signals. The classification of the sensing platforms is generally presented according to their recognition element, and the most recent achievements by using these attractive sensing substrates are described in detail. In addition, the current challenges are discussed.

A Membrane Filter-Assisted Mammalian Cell-Based Biosensor Enabling 3D Culture and Pathogen Detection

We have developed a membrane filter-assisted cell-based biosensing platform by using a polyester membrane as a three-dimensional (3D) cell culture scaffold in which cells can be grown by physical attachment. The membrane was simply treated with ethanol to increase surficial hydrophobicity, inducing the stable settlement of cells via gravity. The 3D membrane scaffold was able to provide a relatively longer cell incubation time (up to 16 days) as compared to a common two-dimensional (2D) cell culture environment. For a practical application, we fabricated a cylindrical cartridge to support the scaffold membranes stacked inside the cartridge, enabling not only the maintenance of a certain volume of culture media but also the simple exchange of media in a flow-through manner. The cartridge-type cell-based analytical system was exemplified for pathogen detection by measuring the quantities of toll-like receptor 1 (TLR1) induced by applying a lysate of P. aeruginosa and live E. coli, respectively, providing a fast, convenient colorimetric TLR1 immunoassay. The color images of membranes were digitized to obtain the response signals. We expect the method to further be applied as an alternative tool to animal testing in various research areas such as cosmetic toxicity and drug efficiency.