ABSTRACT

In this talk, I will be discussing the importance of surface sensitive synchrotron X-ray scattering techniques for three different systems. Synchrotron X-rays are commonly used as a tool for studying molecular scale phenomena at an air/water interface. Grazing incidence X-ray diffraction and X-ray reflectivity are applied to understand the interfacial structure at a molecular length scale. The former technique is well suited to determine the in-plane structure (xy-direction) of the Langmuir monolayers, while the latter technique predicts the contribution from all the species in the system in terms of the electron density profile normal to an interface (z-direction). The first part of the talk will focus on the adsorption behavior of monoclonal antibodies (mAbs) and surfactants competing for space at the air/water interface. Loss of mAbs at the air/water interface during drug formulations, storage, shipping and administration to the patients results in the decrease in efficacy and may promote immunogenicity. We have used X-ray reflectivity at the Advanced Photon Source (Sector 15-ID C), Argonne National Laboratory to understand the competitive adsorption of mAbs with surfactants. We will present our experimental and theoretical modeling of the systems,
showing that mAbs tend to adsorb and orient in a flat-on at low surface concentrations and end-on conformation as surface concentration is increased. The second part of the talk will focus on the use of eco-friendly herder surfactants to mitigate the spreading of oil spills. This system was mimicked using MGDG (monogalactosldiacylglycerol) as the eco-friendly surfactant herder,
lambada-carrageenan as the microlayer sea polysaccharides and sea salts (Calcium for this study). Another independent technique, X-ray fluorescence near total reflection was used to study the monolayer binding of MGDG and lambdacarrageenan using charged divalent cations [Ca+2]. We show that the surfactant monolayer material yields the number of accumulated Ca+2 per lipid at the
surface. This work is in collaboration with Prof. Maldarelli and graduate student Hao Zho (Levich Institute, CUNY)
The third part of the talk will define the use of grazing incidence X-ray diffraction (GIXD) to understand the in-plane structure of the molecules on an air/water interface. The molecules studied belong to a new class of shape-persistent, helical molecules that contain multiple helicenes, named as naphthalene-linked, perylene-diimide-based nanoribbon (NP3H). The Bragg peak information from GIXD is correlated to the area per molecule and the hexagonal packing of the molecules at the air/water interface. The details about the theoretical modeling of the system will be discussed in this part of the talk. This work is in collaboration with Prof. Colin Nuckolls and graduate student Neil Foegen (Department of Chemistry, Columbia University)

BRIEF ACADEMIC/EMPLOYMENT HISTORY:

Ankit was born and raised in Mumbai, India. He received his BE in Chemical Engineering in 2016 from Institute of Chemical Technology, Mumbai, India and came to CCNY in the Fall of 2016. Ankit’s research is in collaboration with the Bristol-Myers Squibb Pharmaceutical Co., New Brunswick, NJ, and he is interested to continue in pharmaceuticals after his graduation.

MOST RECENT RESEARCH INTERESTS:

Biomacromolecules at interfaces, protein aggregation and stability, interfacial science and engineering.