Colloidal suspensions : from Janus motors to antibody solutions

Abstract

From ketchup to toothpaste, colloids are as ubiquitous as they are useful to people’s lives. As technology involving colloids advances, we are finding new and interesting ways to take advantage of colloidal suspensions. One application is the idea of the “magic bullet” – an agent that could be administered to a patient to neutralize pathogens with pinpoint accuracy while leaving healthy tissue unaffected. More than a hundred years since the conception of the magic bullet, advances in micro/nanotechnology and antibody engineering are making it a reality. Janus motors present the opportunity to design colloidal particles with the ability to preferentially seek out specific cellular targets while novel antibody therapeutics have specificity not found in many other treatments.

In the second half of this work we improve upon the existing colloidal models for the prediction of the rheological properties of antibody solutions. We refuted the perceived shortcomings of the colloidal interpretation by developing a model that combines short-range attractive interactions with long-range repulsive interactions.

Pt/H2O2 Janus motors in viscosified Newtonian solutions of sucrose or glycerol. We showed that propulsion depends not only on just the solution viscosity, but on how the choice of the viscosifying agent uniquely impacts the interactions between the motor and fuel molecules.

This work is divided into two parts. The first concerns itself with Janus motors, self-propelling colloidal particles that offer the possibility of designing drugs that can seek out treatment targets. To aid in the design of self-propelling particles, we examined the statistics involved in the analysis of such particles. This involved the simulation of self-propelling particles in order to determine how physical parameters, such as propulsive speed, and design parameters, such as video length and fitting region, affect the precision and accuracy when analyzing videos of self-propelling particles. The results provide insight on how to improve experiments on self-propelling particles. Biological applications of Janus motors require that the motors navigate complex fluids that are viscous/viscoelastic in nature. To this end, we examine the motion of

Unfortunately, these using these technologies are not without challenges. While Janus motors displaying fantastic propulsive speeds of over a hundred body lengths per second, self-propulsion through the non-Newtonian fluids frequently found in the human body is poorly understood. Antibody therapeutics may be an effective treatment for cancer, heavy development and production costs prevent such treatments from being more common. A major problem encountered during the development of antibody therapeutics is that of syringeability. When prepared in the highly concentrated form required for treatments, many antibody solutions become too viscous to be administered via subcutaneous injection.