Advanced diagnostic methods for identification of bacterial foodborne pathogens: contemporary and upcoming challenges

It is a public health imperative to have safe food and water across the population. Foodborne infections are one of the primary causes of sickness and mortality in both developed and developing countries. An estimated 100 million foodborne diseases and 120 000 foodborne illness-related fatalities occur each year in India. Several factors affect foodborne illness, such as improper farming methods, poor sanitary and hygienic conditions at all levels of the food supply chain, the lack of preventative measures in the food processing industry, the misuse of food additives, as well as improper storage and handling. In addition, chemical and microbiological combinations also play a key role in disease development. But recent disease outbreaks indicated that microbial pathogens played a major role in the development of foodborne diseases. Therefore, prompt, rapid, and accurate detection of high-risk food pathogens is extremely vital to warrant the safety of the food items. Conventional approaches for identifying foodborne pathogens are labor-intensive and cumbersome. As a result, a range of technologies for the rapid detection of foodborne bacterial pathogens have been developed. Presently, many methods are available for the instantaneous detection, identification, and monitoring of foodborne pathogens, such as nucleic acid-based methods, biosensor-based methods, and immunological-based methods. The goal of this review is to provide a complete evaluation of several existing and emerging strategies for detecting food-borne pathogens. Furthermore, this review outlines innovative methodologies and their uses in food testing, along with their existing limits and future possibilities in the detection of live pathogens in food.

Low-cost, open-source 3D printed antibody dispenser for development and small-scale production of lateral flow assay strips

We present a low cost, 3D printed open-source antibody dispenser that can be easily built and used for the development of lateral flow assay (LFA) strips. The fabrication of LFA strips need dispensing of antibodies or antigens in a linear fashion and commercially available dispensers typically cost from few thousands to few tens of thousands of US dollars. In this paper, an antibody dispenser was built by using 3D printed and commercially available parts, which cost no more than 30 USD. This paper presents a detailed instruction on how to assemble the printer and how to achieve a specific line width for the dispensed antibody. By using syringe needles of different gauges, line width ranging from 0.23 to 1.8 mm can be dispensed, and by varying the speed controller, the dispensing needle's speed can be varied between 2.8 and 3.8 cm/s. We demonstrate uniform dispensing of anti-C-reactive protein (CRP) antibody and anti-rabbit antibody to draw a test line and a control line, which are used for the detection of CRP. The dispenser can also be equipped with two dispensing needles to allow simultaneous dispensing of multiple reagents, which can be useful for LFA strip development.

Functionalized AuMBA @Ag Nanoparticles as an Optical and SERS Dual Probe in a Lateral Flow Strip for the Quantitative Detection of Escherichia coli O157:H7

A method combining surface-enhanced Raman scattering (SERS) with a lateral flow strip (LFS) was developed for the quantitative and sensitive analysis of Escherichia coli O157:H7. Au^MBA @Ag nanoparticles were prepared as SERS probes, and 4-methylthiobenzoic acid (MBA) as a Raman reporter was inserted into the interior gap of the Au@Ag core-shell nanoparticles, which replaced the Au nanoparticles that serve as SERS nanotags in traditional LFS. Using this developed SERS-LFS, the presence of the target bacteria could be tested through the appearance of a red band on the test line. Furthermore, quantitative analysis of E. coli O157:H7 was achieved by measuring the specific Raman intensity of MBA on the test line. The sensitivity of this SERS-LFS biosensor is 5 × 10⁴ CFU/mL of E. coli O157:H7, which is 10-fold higher than that of a naked eye-based colorimetric LFS. This quantitative detection of E. coli O157:H7 ( Y = 1993.86 X - 6812.17, R² = 0.9947) was obtained with a wide linear range (5 × 10⁴ to 5 × 10⁸ ) due to the signal enhancement of the SERS nanotags. In addition, the SERS-LFS could differentiate E. coli O157:H7 from closely related bacterial species or nontarget contaminants, suggesting high specificity of this assay. The applicability of SERS-LFS to the analysis of E. coli O157:H7 in milk, chicken breast, and beef was also validated, indicating that the sensitivity was not disturbed by the food matrix. In summary, the SERS-LFS developed in this study could be a powerful tool for the quantitative and sensitive screening of E. coli O157:H7 in a food matrix. PRACTICAL APPLICATION: This study demonstrates that a surface-enhanced Raman scattering (SERS)-based lateral flow strip (LFS) could be used as a rapid and sensitive method for Escherichia coli O157:H7 detection. Furthermore, this SERS-based LFS could achieve quantitative detection of the target, eliminating the defect of the traditional colloidal gold LFS, which is not quantifiable.