Biomimetic nano cargo carriers

A tiny transport system, inspired by micro-scale motion in bacterial cilia and flagella, has been developed by a team at the Indian Institute of Technology Madras and the Institute of Mathematical Sciences, in Chennai, India. The system could carry colloidal particles in fluids or gels to target sites more rapidly than is possible through simple diffusion. [RK Manna et al. J Chem Phys (2017); DOI:  10.1063/1.4972010]

"Microorganisms have developed specialized organelles, such as cilia and flagella, to overcome the challenges of, in the words of Edward Purcell, 'life at a low Reynolds number'," explains IIT graduate student member of the team Raj Kumar Manna. "Recent experiments demonstrated that flagella-like 'beating' could be achieved in vitro, proving it's possible to obtain a periodic beating motion without complex biological regulation."

The team has now extended a model of active filaments that accommodates hydrodynamic interactions and so allows them to understand what factors might affect transport of colloidal particles. With this new knowledge in hand they were then able to design an active transport engine. The new work builds on science dating back to the middle of the nineteenth century and carried out by mathematician George Stokes, which was advanced by physicist Marian Smoluchowski in the early 1900s to quantify friction and the so-called hydrodynamic interaction.

"We have applied these techniques to the new situation of swimming within a viscous fluid," adds P B Sunil Kumar of IIT Madras. The team has now designed a colloidal transport system using synthetic active filament that is completely biocompatible and could have applications in drug delivery, lab-on-a-chip analytical and diagnostic devices, and perhaps therapeutic interventions where defective motility in physiology is an issue.

"It's difficult to predict the timing for a computer design to be realized experimentally, and then go beyond clinical trials to medical use. But, if past development within this area is any guide, we expect some of these technologies to become feasible within a decade or so", says R. Adhikari of the Institute of Mathematical Sciences. The next step for the group will be to increase the degree of realism in their model and analysis so that they can model the system in an environment that more resembles blood and to look at the effects of branched geometries that look like capillaries, the researchers say. They will also look at how they might work with experimentalists to see how the theoretical works in practice.

David Bradley blogs at Sciencebase Science Blog and tweets @sciencebase, he is author of the popular science book "Deceived Wisdom".