Continuous, rapid concentration of foodborne bacteria (Staphylococcus aureus, Salmonella typhimurium, and Listeria monocytogenes) using magnetophoresis-based microfluidic device
Introduction
Foodborne bacteria constitute a major public health concern worldwide. According to the World Health Organization, one in every six Americans suffers from foodborne disease in the United States, or approximately 48 million people annually. Globally, there are approximately 600 million people suffering from foodborne diseases and 420,000 deaths every year (Wang et al., 2017). Staphylococcus aureus (S. aureus), Salmonella typhimurium (S. typhimurium), and Listeria monocytogenes (L. monocytogenes) are the main causes of foodborne diseases (Hennekinne, De Buyser, & Dragacci, 2012). In the United States, approximately 241,000 people contract diseases due to S. aureus, which is frequently found in egg and dairy products and salad (Argudín, Mendoza, & Rodicio, 2010; Tamarapu, McKILLIP, & Drake, 2001). Therefore, there is a growing demand for food safety (Zhao et al., 2016), and rapid and accurate on-site detection is essential to prevent foodborne diseases.
Culture and colony counting is the gold standard method of bacteria detection. This method is highly accurate, but it takes one to five days to identify the cause of foodborne disease (Fratamico, 2003). As alternatives to culture-based detection, polymerase chain reaction (Alves, Marques, Pereira, Hirooka, & De oliveira, 2012; Xu et al., 2016) and enzyme-linked immunosorbent assay (Suo et al., 2010; Zadernowska, Chajęcka-Wierzchowska, & Kłębukowska, 2014) techniques have been used to reduce the detection time. However, these methods require skilled operators and expensive equipment. Therefore, various biosensors have been studied for fast, accurate, and easy detection (Dos Santos et al., 2013; Longo et al., 2013; Vaisocherová-Lísalová et al., 2016; L.; Yang & Bashir, 2008). Most biosensors use small amounts of sample (a few tens of microliters) to detect bacteria (Abbaspour, Norouz-Sarvestani, Noori, & Soltani, 2015; Dong, Zhao, Xu, Ma, & Ai, 2013). However, the maximum acceptable limit for bacterial contaminants is 0 CFU/mL in Korea. Thus, it is necessary to perform bacteria detection with at least a few milliliters of the sample to obtain statistically significant results (Petersen et al., 1998). Small amounts of samples with low concentration may lead to a false negative result in bacteria detection because the samples may not contain the bacteria. In this case, detection must be conducted several times to process a statistically significant volume of the sample (a few milliliters). Moreover, most biosensors have low detection limits of approximately 101–102 CFU/mL (Li et al., 2013; Sharma & Mutharasan, 2013; Wang, Wang, Chen, Kinchla, & Nugen, 2016; Wang, Ping, Ye, Wu, & Ying, 2013), which is still higher than the bacteria detection criterion for food samples. Nevertheless, it is possible to obtain results satisfying this criterion by concentrating a food sample from a few milliliters to a few tens of microliters. In this manner, the volume of the sample can be reduced and the statistical significance can be enhanced. Therefore, sample pretreatment, such as bacteria concentration, is crucial for rapid and accurate detection of foodborne bacteria.
Magnetophoresis-based bacteria concentration devices have been extensively studied to reduce the sample pretreatment time (Lee et al., 2009; Mizuno et al., 2013; Yang et al., 2016). The target sample can be labeled with various biologically active groups that are conjugated with magnetic particles (MPs) (Feng, Dai, Tian, & Jiang, 2018; Liébana et al., 2016; Setterington & Alocilja, 2011). The MP-conjugated bacteria (MP/Bac) can be separated from the food matrix by attracting them with an external magnetic field. In particular, microfluidic-based continuous sample pretreatment devices have been actively studied for rapid sample concentration. The microfluidic platform presents multiple advantages such as small size, portability, low cost, and easy integration with various types of devices (Forbes & Forry, 2012; Lee, Hatton, & Khan, 2011; Ngamsom et al., 2016; Pamme, Eijkel, & Manz, 2006; Robert et al., 2011). However, most magnetophoresis-based concentration devices are fabricated as two-dimensional structures and have very short channel lengths. Therefore, the MPs cannot sufficiently move toward the channel wall near the magnet under high flow rate conditions, limiting the separation efficiency. Moreover, the device size and the distance between the channel and the magnet increase with increasing channel length because both the microfluidic channel and the magnet should be placed on the two-dimensional space. Thus, magnetophoresis-based continuous bacteria concentration devices have low throughput.
Herein, a magnetophoresis-based microfluidic device is proposed for rapid separation and concentration of bacteria in food samples. A commercial polyethylene tube channel with an inner diameter of 280 μm was wrapped around a neodymium permanent magnet (5 mm × 5 mm × 50 mm) in a three-dimensional (3D) coil manner. The distance between the tube and magnet was held constant using a 3D-printed support structure. The channel length of the suggested device can be adjusted easily to provide enough time for the MPs to be attracted by the magnet, even under a high flow rate. Thus, the MP/Bac in the fluid channel can move to the inner wall of the channel by the permanent magnet, improving the separation efficiency under a high flow rate.
Section snippets
Design
Fig. 1 shows a schematic of the continuous bacteria concentration device. The fluidic channel consists of tube and polydimethylsiloxane (PDMS) channels. The inner and outer diameters of the tube channel are 280 μm and 640 μm, respectively. A 5 mm × 5 mm × 50 mm (width × height × length) permanent magnet was placed inside the support with a thickness of 1 mm. The support has a groove structure with the 350 μm of the radius of curvature, and the tube channel is wrapped in a coil shape from top to
Analysis of particle behavior and channel length optimization
To increase the separation efficiency and concentration factor under high flow rate conditions, the particles injected into the inlet must move to the inner wall of the channel before reaching the outlet. In this study, the residence time was controlled by adjusting the tube channel length to facilitate particle movement to the channel wall. The optimum channel length was determined based on the particle velocity. The residence time is the period during which the injected particles stay in the
Conclusion
A magnetophoresis-based microfluidic device was developed for rapid and continuous bacteria concentration. The device was fabricated with a 3D structure by combining a commercial polyethylene tube and PDMS channel. The bacteria were concentrated under a high flow rate by adjusting the channel length. An optimum channel length of 12, 10, and 14 turns was determined at a flow rate of 40 mL/h using the particle velocities of MP/Sta, MP/Sal, and MP/Lis, respectively. The calculated optimum channel
CRediT authorship contribution statement
Taekeon Jung: Conceptualization, Writing - original draft, Methodology, Investigation, Validation. Yugyung Jung: Methodology, Investigation. Jaehyeon Ahn: Software, Validation. Sung Yang: Conceptualization, Supervision, Writing - review & editing.
Acknowledgements
This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korean government (MSIP) (NRF-2016M3A7B4910556).
References (35)
- et al.
Aptamer-conjugated silver nanoparticles for electrochemical dual-aptamer-based sandwich detection of staphylococcus aureus
Biosensors and Bioelectronics
(2015) - et al.
A label-free electrochemical impedance immunosensor based on AuNPs/PAMAM-MWCNT-Chi nanocomposite modified glassy carbon electrode for detection of Salmonella typhimurium in milk
Food Chemistry
(2013) - et al.
Detection of Listeria monocytogenes based on combined aptamers magnetic capture and loop-mediated isothermal amplification
Food Control
(2018) Comparison of culture, polymerase chain reaction (PCR), TaqMan Salmonella, and Transia Card Salmonella assays for detection of Salmonella spp. in naturally-contaminated ground chicken, ground Turkey, and ground beef
Molecular and Cellular Probes
(2003)- et al.
Microfluidic continuous magnetophoretic protein separation using nanoparticle aggregates
Microfluidics and Nanofluidics
(2011) - et al.
A sensitive method to detect Escherichia coli based on immunomagnetic separation and real-time PCR amplification of aptamers
Biosensors and Bioelectronics
(2009) - et al.
Electrochemical genosensing of Salmonella, Listeria and Escherichia coli on silica magnetic particles
Analytica Chimica Acta
(2016) - et al.
An electrochemical immunosensor for sensitive detection of Escherichia coli O157: H7 using C60 based biocompatible platform and enzyme functionalized Pt nanochains tracing tag
Biosensors and Bioelectronics
(2013) - et al.
Multiplex sorting of foodborne pathogens by on-chip free-flow magnetophoresis
Analytica Chimica Acta
(2016) - et al.
On-chip free-flow magnetophoresis: Separation and detection of mixtures of magnetic particles in continuous flow
Journal of Magnetism and Magnetic Materials
(2006)
Rapid electrochemical detection of polyaniline-labeled Escherichia coli O157: H7
Biosensors and Bioelectronics
Rapid and sensitive immunodetection of Listeria monocytogenes in milk using a novel piezoelectric cantilever sensor
Biosensors and Bioelectronics
Development of an oligonucleotide-based microarray to detect multiple foodborne pathogens
Molecular and Cellular Probes
Development of a multiplex polymerase chain reaction assay for detection and differentiation of Staphylococcus aureus in dairy products
Journal of Food Protection
The importance of particle type selection and temperature control for on-chip free-flow magnetophoresis
Journal of Magnetism and Magnetic Materials
Low-fouling surface plasmon resonance biosensor for multi-step detection of foodborne bacterial pathogens in complex food samples
Biosensors and Bioelectronics
Efficient separation and quantitative detection of Listeria monocytogenes based on screen-printed interdigitated electrode, urease and magnetic nanoparticles
Food Control
Cited by (27)
A multifunctional iron catalyst-based colorimetric sensor for rapid bacterial detection in food
2023, Sensors and Actuators B: ChemicalLab-on-chip separation and biosensing of pathogens in agri-food
2023, Trends in Food Science and TechnologyMicrofluidics-integrated biosensor platform for modern clinical analysis
2023, Health and Environmental Applications of Biosensing Technologies: Clinical and Allied Health Science PerspectiveStrategies for controlling biofilm formation in food industry
2022, Grain and Oil Science and TechnologyCitation Excerpt :Foodborne bacteria consumed along with food cover a wide range of public health concerns worldwide [1]. About 600 million people globally are affected by foodborne diseases such as vomiting, diarrhea, enteritis, abdominal pain, headache, which have become a serious problem in a wide range of food industries, including meat processing, brewing, dairy and poultry [2]. Around more than half of persistent infections are caused by bacterial biofilms in the United States [1].
Lateral flow assays (LFA) for detection of pathogenic bacteria: A small point-of-care platform for diagnosis of human infectious diseases
2022, TalantaCitation Excerpt :Pathogenic bacteria are present in the air, water, soil, and foodstuff spreading mainly by physical contact [9]. They may result in foodborne diseases which are becoming a universal concern due to remarkable economic damages and severe public health problems [10,11]. As soon as the bacteria enter the body, food poisonings and systemic infections such as endophthalmitis, septicemia, pneumonia, diarrhea, and vomiting occur and if the treatment is not started rapidly, it may have been followed by death [12].