(188e) Study of the Effects of Surfactants on the Brownian Motion of Fluorescent Polystyrene Beads in Silicone Oil

Polymer microspheres (beads) are used as agents of molecular diversity in many high-throughput analytical platforms in biochemistry¹. Microspheres also add functionality to microfluidic devices, and are heavily employed in the field of biochemical microfluidics^2-3. As a platform for surface chemistry, they permit reactions at much smaller volumes, and facilitate analyte transport when used in (liquid) suspensions. A freely suspended bead experiences Brownian motion⁴.They usually come with a fluorescent core that allows direct visualization of their Brownian motion using fluorescence microscopy. Fluorescence imaging of beads to track particle motion has been used in many wide range biological applications such as in vivo imaging, and flow determination⁵. But, bead suspension and particle motion in a medium (e.g., silicone oil) that’s more relevant for biochemical reactions hasn’t been extensively studied. Thus, a thorough understanding of the suspension of polymeric beads (e.g., polystyrene), particle motion using fluorescence imaging, and the effect of surfactants on the diffusivity of beads in such medium is an important area of research.

In this work, we present a comprehensive study of the effects of surfactants on the Brownian motion of single polystyrene beads of different diameters in silicone oil of different viscosities for biochemical reactions. The first part of the study deals with the optimal design of experiments that influence surface interactions to increase the Brownian motion of beads such as surfactant type and concentration, viscosity of the suspension medium, bead diameter, density and surface functionalization for bead manipulation. The latter part of the study examines the impact of the optimal design parameters especially the surfactant type and concentration on single particle tracking of polystyrene beads in silicone oil. For particle motion, single particle tracking algorithm is used to track the motion of beads in x and y directions using fluorescence imaging.

References:

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