Microfluidic applications of functionalized magnetic particles for environmental analysis: focus on waterborne pathogen detection

Abstract

The continuous surveillance of drinking water is extremely important to provide early warning of contamination and to ensure continuous supplies of healthy drinking water. Isolation and detection of a particular type of pathogen present at low concentration in a large volume of water, concentrating the analyte in a small detection volume, and removing detection inhibiting factors from the concentrated sample, present the three most important challenges for water quality monitoring laboratories. Combining advanced biological detection methods (e.g., nucleic acid-based or immunology-based protocols) with microfluidics and immunomagnetic separation techniques that exploit functionalized magnetic particles has tremendous potential for realization of an integrated system for pathogen detection, in particular, of waterborne pathogens. Taking advantage of the unique properties of magnetic particles, faster, more sensitive, and more economical diagnostic assays can be developed that can assist in the battle against microbial pathogenesis. In this review, we highlight current technologies and methods used for realization of magnetic particle-based microfluidic integrated waterborne pathogen isolation and detection systems, which have the potential to comply in future with regulatory water quality monitoring requirements.

Applications of Microfluidics in the Agro-Food Sector: A Review

“…The device could detect 0.1 ng/mL of SEB in soy milk. Many reports have indicated that microfluidic devices are effective in enhancing the sensitivity of bacteria detection by concentrating the pathogens in a small volume and removing interfering foreign materials from the sample (Ramadan and Gijs, 2012). Varshney et al (2007) successfully detected levels of E. coli O157:H7 cells as low as 1.2×10 3 cells in a ground beef sample in a time period of 35 min by using a poly(dimethylsiloxane) (PDMS) microfluidic flow cell and an impedance biosensor.…”

“…A concentration step is required for environment monitoring since there is an extremely small number of target pathogens in very large volume samples. Microfluidics provides the ability to prepare samples, and process and detect targets inside a single device in order to minimize the possibility of losing concentrated pathogens (Ramadan and Gijs, 2012).…”

Simultaneous diamagnetic and magnetic particle trapping in ferrofluid microflows via a single permanent magnet

“…5,6 More preferably, particles can be captured in a flowing suspension through the use of an external force, where the accumulated particles can be readily dispersed by either lowering (or switching off) the force field or increasing the flow rate. [2][3][4] A number of non-magnetic force fields, 1,7 including acoustic, 8,9 electric, [10][11][12][13] and optical [14][15][16] forces, have been demonstrated to enrich various types of particles and cells in microfluidic devices. Compared to these contactless methods, magnetic trapping of particles has several advantages such as low cost, heating free (except for electromagnets), and near independence of the suspending medium properties (e.g., ionic concentration and pH value).…”

“…[1][2][3][4] Particles can be immobilized onto solid surfaces through direct contact via either mechanical filters or chemical coatings, which is, however, prone to irreversible adhesions with a potentially high probability of device fouling. 5,6 More preferably, particles can be captured in a flowing suspension through the use of an external force, where the accumulated particles can be readily dispersed by either lowering (or switching off) the force field or increasing the flow rate.…”

Continuous sheath-free magnetic separation of particles in a U-shaped microchannel

“…Moreover, it is non-invasive and free of fluid heating issues (if permanent magnets are used) which accompany nearly all other methods, and is therefore well suited to handling biological particles. [13][14][15][16] However, in many of the reported continuous-flow magnetic separations the particle suspension needs to be first confined by a co-flowing buffer solution. Then, an external magnetic force acts on the suspended particles and deflects them to different flow paths in the sheath stream for a continuous sorting.…”