The overall scientific aim of this proposal was to design, and fabricate in sufficient quantity of novel self-propelled particles with tunable propulsion in order to obtain a detailed real space insight on a single particle level in concentrated dispersion using confocal laser scanning microscopy. Systematic characterization of the proposed model systems will allow me to study when and how microscopic dynamics affect the macroscopic behavior of internal-driven colloidal systems. The research proposal consisted of two distinct but connected research topics. During the period of this project, the applicant was designed and developed three novel light-activated self-propelled particles (SPPs), namely light-activated Janus silica-titania, Janus titania-gold spherical particles, and iron-oxide tip-coated silica rods that give an exquisite control over the propulsion speed. Next, these systems were successfully used as model systems to study the collective behavior of micro-organisms.
The following projects were successfully completed:
i) Developed a novel, light-activated self-propelled particles (Janus TiO2-Au), in which we can, on demand, reverse the particle’s propulsion direction by exploiting the different photocatalytic activities. The control over the activity and the reversibility of direction by wavelength and intensity, combined with the interplay between attractions and repulsions of the individual units allows the colloidal assemblies to undergo both ‘fusion’ and ‘fission’ like transitions, mimicking aspects of multicellular behaviour.
ii) Studied active and passive mixtures, with an emphasis on the possibility to modulate structure of the passive particles by the presence of a few active ones.
iii) Developed light-activated self-propelled rods in order to mimic and study the collective behavior of collective motion of living microorganisms, i.e swarming motions, and bio-film formation.
iv) Confined self-propelled particles in cell-like environment (i.e. giant unilamellar vesicles).
v) Studied the dynamic interaction of active particles with the membrane.
