(241c) Microfluidic Synthesis of Silica Particles and Bioconjugation

Entrapment and retention of materials inside synthesized silica particles is an active research field due to its many industrial, biological and chemical activities including as molecular sieves due to their porosity. Many methods are used to create these particles, however, most require the removal of the templating agent by acid burning or calcining of the organic material which can be detrimental if a sensitive material needs to be preserved. What follows is a fabrication scheme by use of microfluidic channels that will allow particle synthesis and a narrow size distribution, allowing for retention of introduced material or molecules inside the silica particle that can be beneficial in biological applications.

We report on the formation of silica particles with entrapped fluorescent semiconductor CdSe/ZnS quantum dots (QDs) by a fast synthesis method within a microfluidic cell. The hydrophobic nature of the QD surface stabilizes their dispersion in the oil phase. The synthesis of TEOS (tetraethyl orthosilicate), in the presence of Octylamine, by a highly acidic solution within a few minutes gives micronsized particles. The distributed oil phase provides the vestibule for the QDs and as the silica particle is formed at the oil-water interface the QDs are trapped in the core. Appropriate extent of hydrolysis is obtained and gelation at the oil/water interface occurs by the driving force of condensation, possibly lead by the alkylamine. Confocal microscopy images confirm the quantitative capture of the QDs within the formed silica particle. Additionally, we have bioconjugated said Silica particles with antigens, and other proteins.