(4dv) Surfactant Uses in Pulmonary Disease Treatment and Drug Delivery: Marangoni Transport, Dilatational Rheology, and Surfactant Adsorption | AIChE

(4dv) Surfactant Uses in Pulmonary Disease Treatment and Drug Delivery: Marangoni Transport, Dilatational Rheology, and Surfactant Adsorption

Research Experience:

Understanding surfactant behavior is key to understanding many processes that occur on a colloidal scale including detergency, biological self-assembly and the physiology of breathing. This poster will present my PhD and NIH postdoctoral fellow research toward understanding the complex behavior of surfactants with the goal of treating lung disease.

During my PhD, I worked on surfactant-driven Marangoni flows and how they could be harnessed to enhance post-deposition spreading of drugs in the lungs, which is vital for the treatment of obstructive pulmonary diseases like cystic fibrosis. This included three projects examining the flows initiated by one, two, and many surfactant sources. I developed an apparatus designed to take advantage of Beer’s law to precisely measure the displacement of an interface or the transport of an interfacial material during a spreading event caused by a single surfactant source. I also made use of a separate tool I developed to measure the transport of a drug driven by flow from a depositing aerosol of drug and surfactant. Lastly, I used a finite element method to examine the interaction of two surfactant sources during spreading, the first attempt to bridge the gap between single and multiple source surfactant spreading.

During my NIH postdoctoral fellowship, my research expanded into trying to better understand the properties of the native surfactant monolayers in the lung. While this work is ongoing, I have made significant progress in two areas, by redesigning aspects of a microtensiometer to make it better suited for the study of surfactant monolayers at highly curved model alveolar interfaces. The first breakthrough involved outfitting the microtensiometer with a microfluidic pump capable of model-based feedback control. This allowed for the first measurements of surfactant adsorption to constant area interfaces (prior work relied on interface shape and area changes to measure surface tension). The new microtensiometer also allows more precise dilatational and shear rheology of surfactant layers as the surface area of the interface could be directly controlled rather than relying on the nonlinear capillary pressure control that requires small amplitude oscillations. Secondly, I have developed a method for simultaneous microtensiometer and confocal measurements of a bubble interface of alveolar (< 100 µm) dimensions. This allows for the first ever images of micron scale bubble interfaces that can be directly associated with rheological behavior and show how interfacial curvature influences monolayer morphology. These two techniques will be vital in understanding how lung surfactant behavior is altered in diseases such as acute respiratory distress syndrome and may suggest new mechanisms of how the often-fatal disease progresses, as well as how to best treat it.

Research Interests:

My future research will focus on fundamental colloid science in the area of polymers, surfaces, and colloids to understand complex real-world problems. Currently, I am interested in how surfactant driven flows can be used to transport chemical species and particles across complex fluid subphases. To do so, I will need to develop an understanding of how mixed surfactant monolayers alter the structure and rheology of a fluid interface. While a major motivator of my research will be the treatment of lung diseases, the understanding gained from these studies will be useful to a wide range of surfactant based applications ranging from enhanced oil recovery to stabilization of protein based drugs.

I am seeking to use the work done in my PhD and postdoc as a starting point from which to branch off in new directions. I will use the apparatus I developed in my PhD to identify the key controlling parameters involved in surface tension driven transport over complex cellular and porous subphases such as those found on the surface of the lung. I would also use my expertise in finite element analysis techniques to simulate such flows on scales unrealizable for bench top study as well as to correlate and predict my experimental work. Similar techniques could also be used to study the dissolution of solid surfactant particles, to better understand how their unique dissolution could lead to delayed release pharmaceutical systems. I would also look to use the combined microtensiometer/confocal microscope I developed during my postdoc to explore how synergistic surfactant effects lead to changes in film rheology. This device would also be useful in imaging how proteins adsorb to liquid/air interfaces and understanding how such proteins affect a present surfactant layers surface properties, giving much need insight into how to control this phenomenon in applications such as protein storage, especially as the interface curves at alveolar dimensions and even smaller length scales.

Teaching Interests:

I have some experience teaching students at various levels. During my PhD work I took on several teaching assistant positions for undergraduate classes, including a lab class, a thermodynamics class, and a heat and mass transfer class. Most of this was teaching small groups of around 5 to 10 students. I also guest lectured for the heat and mass transfer class for several lectures. During my postdoc, I was a co-instructor for an undergraduate level mass transfer and separations course as well as giving several guest lectures for a graduate level colloids and interfacial science course. While I am comfortable teaching any of the core curriculum, I would be most interested in teaching heat and mass transfer, and fluid dynamics, as these classes interest me the most. I would also enjoy teaching lab classes and thermodynamics. If I were given the opportunity to create my own course, it would be in colloids and surface science. I would be particularly interested in teaching a class on surfactancy, surfactant monolayers, and interfacial dynamics and rheology.