Magnetic particles for in vitro molecular diagnosis: From sample preparation to integration into microsystems

Magnetic Particles for Advanced Molecular Diagnosis

“…Moreover, considering their tendency to agglomeration due to van der Waal and dipole–dipole attractions, and their sensitivity to oxygen, pH, and salts in the environment, the surface of these particles must be modified to increase their physical and chemical stability by providing steric and Coulomb repulsions [40,41]. Nanoparticle surface coatings are usually performed in the synthesis stage, and they involve polymeric coatings using different natural and synthetic structures, such as chitosan, dextran, cellulose, polyethylene glycol, polyvinyl alcohol, polystyrene, or polyethylene imine, liposomes and micelles utilization, core-shell structures using silica, and metallic coatings, such as gadolinium, or other hybrid materials [36,43,44,45,46]. Additionally, magnetic particles can be functionalized with different compounds in order to provide functional groups for further bioactive molecule conjugations [41] through different techniques, such as direct binding, Hong’s method, or bioremediation [40].…”

“…In the context of molecular diagnosis, magnetic particles have been applied for mixing fluids, selectively capturing, concentrating, transferring, and labelling targeted analytes, performing stringency and washing steps, and probing biophysical properties of analytes [37,38,39,46,47,48]. In this tasks, magnetic separation offers a variety of advantages, including high-throughput, low costs, energy consumption efficiency, increased specificity, stability, and sensitivity [27,31,49], and it has been intensively used, since most biological materials are not susceptible to magnetic fields and the magnetic particles can be easily separated from the reaction mixture and re-dispersed after the removal of the magnetic field [30].…”

“…In this tasks, magnetic separation offers a variety of advantages, including high-throughput, low costs, energy consumption efficiency, increased specificity, stability, and sensitivity [27,31,49], and it has been intensively used, since most biological materials are not susceptible to magnetic fields and the magnetic particles can be easily separated from the reaction mixture and re-dispersed after the removal of the magnetic field [30]. Further, the two main applications of magnetic particles in molecular diagnosis will be discussed, specifically for sample preparation and extraction and for molecular detection and readout systems [46].…”

“…Recent years have witnessed a tremendous interest in applying microfluidics for sample preparation, cell separation, cancer diagnosis, and delivery and screening of therapeutic drugs. Microfluidic systems, known as lab-on-a-chip, biochips, or bio-microelectromechanical systems integrate and implement multilaboratory functions, such as chemical synthesis, biochemical operations, or nucleic acid sequencing, onto a single microdevice [46,63,64]. Such systems offer the advantages of limited sample consumption by working with extremely small volumes, low costs, rapid sample screening, portability, and higher sensitivity [63,64,65,66,67,68].…”

“…The process of bioseparation is similar to the magnetic separation previously described. Hence, magnetic particles serve as supports for nucleic acid hybridization, intercalation, and purification, allowing for simple and rapid analyses [46]. Furthermore, a recently developed magnetic-particle-based microfluidic device for point of care assays is the centrifugal microfluidic device, which is a compact disc that incorporates interconnecting channels and chambers.…”