Advanced immunocapture of milk‐borne Salmonella by microfluidic magnetically stabilized fluidized bed

Abstract

The success of microfluidic immunocapture based on magnetic beads depends primarily on a sophisticated microscale separation system and on the quality of the magnetic immunosorbent. A microfluidic chip containing a magnetically stabilized fluidized bed (μMSFB), developed for the capture and on‐chip amplification of bacteria, was recently described by Pereiro et al.. The present work shows the thorough development of anti‐Salmonella magnetic immunosorbents with the optimal capture efficiency and selectivity. Based on the corresponding ISO standards, these parameters have to be high enough to capture even a few cells of bacteria in a proper aliquot of sample, e.g. milk. The selection of specific anti‐Salmonella IgG molecules and the conditions for covalent bonding were the key steps in preparing an immunosorbent of the desired quality. The protocol for immunocapturing was first thoroughly optimized and studied in a batchwise arrangement, and then the carrier was integrated into the μMSFB chip. The combination of the unique design of the chip (guaranteeing the collision of cells with magnetic beads) with the advanced immunosorbent led to a Salmonella cell capture efficiency of up to 99%. These high values were achieved repeatedly even in samples of milk differing in fat content. The rate of nonspecific capture of Escherichia coli (i.e. the negative control) was only 2%.

Biosensors for rapid detection of Salmonella in food: A review

“…Nowadays, much effort has been focused on novel sample pretreatment methods that are potential to be integrated into biosensors, including IMS (Du et al., 2018), microfluidic separation (He et al., 2013; Liu et al., 2019; Srbova et al., 2018), electrophoresis (Nguyen, Nguyen, Bui, & Seo, 2019; Zhang, Luo, et al., 2018), acoustophoresis (Ngamsom, Lopez‐Martinez, et al., 2016), magnetophoresis (Ngamsom, Esfahani, et al., 2016), and magnetic ionic liquid‐based extraction (Hice, Clark, Anderson, & Brehm‐Stecher, 2019). Among them, IMS has been regarded as one of the most useful tools for selective capture, separation, and concentration of Salmonella prior to detection.…”

Overview of Rapid Detection Methods for Salmonella in Foods: Progress and Challenges

“…But the non-specific enrichment easily misses the target bacteria and reduces the accuracy of Salmonella detection. Nowadays, many kinds of Salmonella sorting technologies have been developed, such as magnetic separation, electrophoresis, microfluidic screening and so on (Figure 4A) [72,[134][135][136]. Immunomagnetic separation is the widely recognized method for the isolation and enrichment of Salmonella.…”

Recent Advances in Microfluidic Devices for Contamination Detection and Quality Inspection of Milk

“…Thus, the problem of developing microfluidic platforms for the on-site detection of common foodborne pathogens in milk samples has attracted great interest in the recent literature. Typically, these platforms have been designed for the detection of E. coli [ 86 , 90 , 91 , 92 , 93 ], S. aureus [ 94 , 95 , 96 ], Listeria [ 97 , 98 , 99 ], and Salmonella [ 100 , 101 , 102 , 103 , 104 ].…”

“…Many microfluidic devices have been proposed for the detection of Salmonella in milk samples. Generally speaking, these devices use colorimetric, immunoassay (microchip-based, thread-based, rotary paper-based), EC biosensing, fluorescence, and PCR amplification combined with LIF [ 100 , 101 , 102 , 103 , 104 ]. For example, An et al [ 108 ] presented a microfluidic lab-on-a-chip platform in which a microfluidic droplet device was used to encapsulate single Salmonella cells in a growth medium and the encapsulated droplets were then collected.…”