ABSTRACT
Critical Offset Magnetic PArticle SpectroScopy (COMPASS) is a new method that allows to detect slight changes in the mobility of particles in a solution very sensitively. While first applications in detecting biomarkers such as SARS CoV 2 antibodies show very promising results, the full potential of the technique and the underlying physical effects were yet only considered superficially. Here we present the first results of a detailed study of the behavior of the particle signal under variations of relevant system parameters with a focus on particle size, viscosity and temperature of the solution to win more information about the behavior of the effect and find new interesting application possibilities. © 2023 Günther et al.;licensee Infinite Science Publishing GmbH.
ABSTRACT
Current bioassays for detection of antibodies or antigens such as ELISA (Enzyme-linked Immunosorbent Assay) are relatively inflexible, expensive and time-consuming. Upcoming methods, such as ACS (AC susceptometry) or MPS (Magnetic Particle Spectroscopy), exploit the magnetization response of functionalized magnetic nanoparticles (MNP) ensembles to assess specific information about the MNP mobility as well as conjugations of chemical or biological compounds on their surface. Both methods have shown promising results in the past but cannot reach the sensitivity of above-mentioned techniques. We used a novel method based on a modified MPS being sensitive to minimal changes in mobility of MNP ensembles. This facilitates robust and easy-to-handle measurements of minimal changes in the diameter of MNPs. As an example, we detected SARS-CoV-2 antibodies binding to the S1 antigen on the surface of functionalized MNPs. Without any purification or incubation, we could show a sensitivity of less than 50 ng/mL of SARS-CoV-2 antibodies in samples. © 2023 Infinite Science Publishing.