ChE MS Thesis Defense: Richard Gyamfi Atta

 Name: Richard Gyamfi Atta

Title: Understanding Mucus-Bile Salt/ Phospholipid Mixed Micelle Interactions

Date: 04/07/2026

Time: 03:30:00 PM

Committee Members:
Prof. Steve Lustig (Advisor)
Prof. Rebecca Carrier
Prof. Srirupa Chakraborty
Dennis Leung

Location: Forsyth 128

Abstract:
Bile salt–phospholipid mixed micelles play a central role in gastrointestinal transport of lipids and poorly water-soluble drugs, yet their interactions with mucin networks remain poorly understood at the molecular level. Here, we combine time-resolved ATR-FTIR spectroscopy, two-dimensional correlation analysis, diffusion modeling, and isothermal titration calorimetry to resolve the sequence, energetics, and transport behavior of micelle–mucin interactions. The mucin network is first shown to relax into an equilibrium state governed by a glycan-dominated structural hierarchy. Upon exposure to mixed micelles, this equilibrated network undergoes a distinct sequence of reorganization initiated by perturbation of hydrogen-bonding interactions, followed by peptide backbone rearrangement and eventual glycan decoupling. Diffusion analysis reveals that micellar assemblies penetrate the mucin network with effective diffusivities on the order of 10⁻⁶ cm²/s despite ongoing structural evolution. Notably, the ability of a constant-diffusivity Fickian model to accurately describe transport under these conditions indicates that molecular-scale reorganization does not substantially alter the effective transport resistance over the measurement timescale, establishing a direct connection between spectroscopic dynamics and macroscopic transport behavior.

Calorimetric measurements further demonstrate a concentration-dependent transition from localized, enthalpy-driven binding at low micelle concentrations to cooperative, entropy-dominated network disruption at higher loadings associated with higher-order micellar aggregates. Together, these results show that bile salt micelles actively remodel mucin networks rather than traversing a static barrier, while maintaining effective diffusive transport. This work provides a molecular-level framework for understanding mucus- mediated transport and its implications for physiological processes and drug delivery.

Richard Gyamfi Atta is a Master’s candidate in Chemical Engineering at Northeastern University, where he conducts research in the Carrier and Lustig laboratories on transport phenomena across biological barriers. His work focuses on elucidating the molecular mechanisms governing interactions between bile salt–phospholipid assemblies and mucin networks, with the goal of improving drug transport across the gastrointestinal mucus layer. By integrating time-resolved ATR-FTIR spectroscopy, two-dimensional correlation spectroscopy, diffusion modeling, and calorimetry, he develops mechanistic frameworks that connect molecular-scale interactions to macroscopic transport behavior in complex biopolymer systems. In addition to his academic research, Richard has industry experience in gene therapy process development, where he contributed to downstream purification strategies for adeno-associated virus (AAV) vectors, including optimization of chromatography and filtration processes to improve product recovery and quality. His research interests are centered on pharmaceutical drug delivery, particularly the design of biomaterials and carrier systems that enhance the transport of poorly soluble drugs and biologics across mucosal and other physiological barriers. He aims to develop mechanistically driven approaches that bridge molecular interactions, material design, and transport phenomena to enable more effective and predictable drug delivery systems.