Self-assembling aramid amphiphiles

Advisors: Prof. Julia Ortony
Institution: Department of Materials Science and Engineering, Massachusetts Institute of Technology (MIT)
Conference: S.Kallakuri, J. Tian, J. H. Ortony. A Novel, Biomimetic, Amphiphilic System for Superior Arsenic Chelation from groundwater. MRS Fall Meeting, Boston, MA, 2017.

Introduction

Designed and synthesized head-groups for the synthesis of self-assembling aramid amphiphiles to extract heavy-metals from groundwater and later extended into molecular catalysis. The molecules designed and synthesized here served as the initial prototypes and laid groundwork for future development of this platform in the following paper in Nature Nanotechnology (DOI: 10.1038/s41565-020-00840-w)

Abstract

Arsenic contaminated groundwater is a global problem that affects nearly 160 million people worldwide, and is a major cause for chronic illness and disease in these contaminated regions. Numerous human activities and industrial pollution, have led to a rapid rise in its groundwater content and accumulation. In the efforts to remediate Arsenic, a major difficulty lies in the transmutability of its various forms, and their generally odorless, colorless, prosaic nature. Existing methods for the removal of Arsenic from ground and drinking water are mainly based on Reverse Osmosis, Adsorption, and Distillation. While reverse osmosis and distillation are effective, they are expensive and require frequent replacement and maintenance. Adsorption based methods suffer from lower efficiencies and expensive materials.
Our current approach is focused on a Chelation based model for the removal of Arsenic by the development of a self-assembling, biomimetic Arsenic chelating lipid system, capable of assembling into vescicles and fibres. This framework is further extensible to numerous other diverse applications such as solar energy generation, fuel cells, and other heavy metal remediation. Our system utilizes a zwitterionic amphiphile synthesized from inexpensive starting materials, and engineered to contain an arsenic chelation end that was modelled on mechanisms for Arsenic toxicity in humans. The synthesized complete amphiphilic moiety thus possesses strong Arsenic chelation ability along with self-assembling properties necessary for formation of macrofibres and networks. The Arsenic complex formed here has been shown to be a particularly stable one with a binding constant of nearly $4*10^{18}$.
Through the utility of this amphiphile, we are developing a highly efficient low-cost filter membrane system with an indicator, that would remediate Arsenic completely from groundwater to the WHO limit of 10 ppb, while addressing the limiting problems of affordability in urban and rural areas, ease of global scale-up, and maintenance.