Magnetic two-particle cluster dynamics for biosensing

PhD project Andrea Ranzoni

The objective of this project is to develop a new technology to achieve fast and quantitative detection of low concentrations of proteins, applying controlled torque and rotation to clusters of superparamagnetic particles. The clusters are formed by incubating antibody-coated magnetic particles with a sample fluid. For protein concentrations lower than the particle concentration, the sample will contain mainly single particles and two-particle clusters. The biosensing concept is to exploit the unique rotational dynamics of particle clusters as a tool to determine the particle cluster concentration and thereby the protein concentration.

The first phase of this project focuses on the characterization of the rotational dynamic of individual two-particle clusters and methods to quantify the torque applied by each cluster. The magnetic energy equations and the equations of motion for two-particle micro- and nanoactuators have been developed, including contributions from the permanent and induced magnetic moments of the particles. A comparison of theory and experiments shows that the magnetic moments can be determined with an accuracy better than 10% across a wide frequency range. The high reproducibility of the response stems from the well-defined magnetic anisotropy of the two-particle clusters.

Reference: A. Ranzoni et al, 'Magnetically controlled rotation and torque of uniaxial microactuators for lab-on-a-chip applications', Lab Chip 2010

This work is supported by MicroNed 2C.