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Title: AC electrokinetic analysis of chemically modified microparticles
Author: Morganti, Diego
ISNI:       0000 0004 2727 4159
Awarding Body: University of Southampton
Current Institution: University of Southampton
Date of Award: 2012
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Electrokinetic manipulation offers a flexible and versatile tool to analyse and precisely handle microparticles, it is non invasive and can be easily implemented in microfluidic devices. Those characteristics make the electrokinetic methods appealing in the field of medical diagnostics because of their ability to perform analysis on a single particle basis, for example to detect binding events of biomolecules such as antibodies and nucleic acids. The detection is performed without fluorescent tags or chemical modifications, because it uses the electrical properties of the surface of the particles as label. The aim of this project is to study the electrical properties of microparticles according to the chemical properties of their surface using electrokinetic on a single particle basis. A new method to analyse single particles that relies on electrorotation and electroorientation has been introduced. Using quadrupolar electrodes it has been possible to obtain both spectra for the same particle allowing a combined fitting of the data. Rod shaped particles have been analysed after each step of the biochemical modifications needed to obtain a surface functionalised with antibodies. We found that the chemical modifications happen mostly in the bulk of the particles, therefore not many charges were available onto the surface. Anyway, it has been possible to distinguish different types of particles using the surface conductance of the particles and their permittivity. Along with biochemically modified particles, also metal coated particles have been analysed to study the electrical double layer under different conditions, like different suspending medium conductivities and surface functionalisations. Particles of different shapes were metal coated with gold after a suitable chemical modification to sensitize their surface. The gold coating is an autocatalytic electroless process; therefore it has been used to plate particles in suspension without the need of an external current source. Metal coated particles’ behaviour is dominated by the double layer at low frequency, but the results are only in qualitative accord with the theory due to the roughness of the metal surface.
Supervisor: Morgan, Hywel Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: QA75 Electronic computers. Computer science ; QD Chemistry