Hybrid Magnetic-DNA Directed Immobilisation Approach for Efficient Protein Capture and Detection on Microfluidic Platforms

Abstract

In this study, a hybrid magnetic-DNA directed immobilisation approach is presented to enhance protein capture and detection on a microfluidic platform. DNA-modified magnetic nanoparticles are added in a solution to capture fluorescently labelled immunocomplexes to be detected optically. A magnetic set-up composed of cubic permanent magnets and a microchannel was designed and implemented based on finite element analysis results to efficiently concentrate the nanoparticles only over a defined area of the microchannel as the sensing zone. This in turn, led to the fluorescence emission localisation and the searching area reduction. Also, compared to processes in which the immunocomplex is formed directly on the surface, the proposed approach provides a lower steric hindrance, higher mass transfer, lower equilibrium time, and more surface concentration of the captured targets leading to a faster and more sensitive detection. As a proof-of-concept, the set-up is capable of detecting prostate-specific membrane antigen with concentrations down to 0.7 nM. Our findings suggest that the approach holds a great promise for applications in clinical assays and disease diagnosis.

Microfluidics Based Magnetophoresis: A Review

“…The disadvantage with electromagnets is that they need external power for generating the magnetic field and this in turn can lead to Joule heating which is unsuitable for most biological applications . Although electromagnets produce a high magnetic gradient, they yield a low magnetic induction – 100 times smaller than that reported by the permanent magnets ,,. In addition, the design and fabrication processes of the circuitry is complex …”

“…The first option is Neodymium‐Iron‐Boron (NdFeB) permanent magnets . Permanent magnets of several shapes and arrangements can be positioned in proximity of the microchannel to generate the desired magnetic fields (∼0.5–1 Tesla) and field gradient (hundreds of Tesla/meter) for manipulating cells and microparticles ,. Herein, the required F m is achieved without any external power and their setup is easy compared to other sources of magnetic field.…”

Research on magnetic bead motion characteristics based on magnetic beads preset technology

“…Magnetic bead is a kind of magnetic material with particle size between 1 and 100 nm, which not only has unique surface effect, volume effect, quantum size effect, functional groups like other general nano material, but also exhibits superparamagnetism, magnetic responsiveness, high coercivity 1 , and can be controlled by external magnetic field. At present, magnetic bead is attracting more and more attention 2 – 5 , and is widely used in biomedical science 6 – 11 . For example, the magnetic beads with special surface treatment can be used to form a new complex by nonspecific or specific combination with the corresponding target materials, and can be separated under the control magnetic field.…”

Research on Magnetic Bead Motion Characteristics based on Magnetic Beads Preset Technology

“…Magnetic bead is one kind of magnetic material with particle size between 1~100nm, which not only has unique surface effect, volume effect, quantum size effect, functional groups like other general nano material, but also exhibits superparamagnetism, magnetic responsiveness, high coercivity , and can be controlled by external magnetic field. At present, magnetic bead has been attracted more and more attention [2][3][4][5] , and are widely used in biomedical science [6][7][8][9][10][11] . For example, the magnetic beads with special surface treatment can be used to form a new complex by nonspecific or specific combination with the corresponding target materials, and be separated under the control magnetic field, than the separated magnetic beads are eluted by the eluent to complete DNA extraction [12][13] .…”