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Institute Distinguished Lecture by Dr. Guruswamy Kumaraswamy

                     Institute Distinguished Lecture on "Controlling the Assembly of Lipid Molecules"

                   The Indian Institute of Technology Bombay was organised on April 12, 2018

                                                      Title:  Controlling the Assembly of Lipid Molecules        

                                                        Speaker: Dr. Guruswamy Kumaraswamy

                                                            Polymer Science and Engineering
                                                     Division, CSIR-National Chemical Laboratory, Pune.

Lipid assemblies are ubiquitous in Nature, and in several technological applications. Indeed, lipids are essential to life since they assemble to form membranes that constitute our cell walls. The curvature of lipid assemblies is a crucial aspect of their structure, since it plays a role in determining the activity of enzymes embedded in lipid membranes. The text book view teaches us that the local curvature in lipid assemblies is controlled by a remarkably simple geometric packing parameter, which is the ratio of the size of the polar headgroup to the hydrophobic lipid tail. We present results that show that there are other routes to controlling curvature in lipid
assemblies.  Specifically, we demonstrate that polar macromolecular dendrons can induce monoolein assemblies to form rare inverse micelle phases.  Further, we establish selection rules for molecules that, when added to monoolein/water systems, are capable of inducing transitions in curvature.  Establishing such rational design rules represents a significant advance in understanding since a multitude of complex interactions determines structure in lipid assemblies. Finally, we demonstrate the use of monoolein nanoparticle dispersions in a practical application: to enhance the efficacy of pesticide delivery.

Pesticides are sprayed as aqueous solutions that do not wet hydrophobic leaf surfaces. This leads to overuse, with environmental implications for soil and groundwater. We demonstrate that monoolein nanoparticle dispersions exhibit remarkable wetting properties on hydrophobic and superhydrophobic substrates.  Wetting of hydrophobic surfaces by lipid nanoparticle dispersions happens by a completely different mechanism when compared with surfactants.  Unlike surfactants, lipid nanoparticles adsorb and reorganize on hydrophobic surfaces to form a thin film that changes the surface wettability – within the millisecond contact times that characterize drop impact.

This novel approach to altering wettability of hydrophobic surfaces has wide ranging implications, beyond improved pesticide delivery. For instance, this work has relevance for printing, improving the lubricity of implantable biomedical devices, among other applications.

About the Speaker:
Dr. Guruswamy Kumaraswamy received a B. Tech in Chemical Engineering from IIT Bombay in 1994, followed by an M.S.(1996) and Ph.D. (2000) in Chemical Engineering from the California Institute of Technology. He spent a year as a VW Postdoctoral Fellow at the Max Planck Institute for Colloids and Interfaces. In 2001, he joined CSIR-National Chemical Laboratory in Pune as a scientist and has been there since. Guruswamy’s work focuses on controlling structure and
investigating structure-property relations in soft matter systems. These systems range from polymers to surfactants and lipids and colloids. He collaborates extensively with industry and has worked with companies in India and abroad in the area of polymers, healthcare, personal care, waste valorization, etc. He is also passionate about science outreach to school students and in the last ten years, he has been associated with a volunteer group called the Exciting Science Group.