(6fh) Dilational Rheology of Lung Surfactant Inhibitors and Its Effects on Acute Respiratory Distress Syndrome

Fluid-fluid interfaces are common in foods, cosmetics, oil/gas industries and in living systems. One such relevant example would be air/water interface in lung surfactants. Adding a curvature on top of the already complex interfacial structure makes it more complicated. It has been observed that the domain size of lung surfactant monolayer is fairly large, approximately 100-300 micron on flat interface which is comparable to the average size of human alveoli, ~150 micron. So, it is important to understand the contribution of curvature and dilatational deformation at the interface. Recent development in interfacial rheological development allows us to measure the response for shear, dilational, and extensional deformations with surface active molecules or particles. These techniques can be even more powerful if added with visualization. We developed instruments/techniques where one can measure the rheological response and see the structural change under deformation simultaneously. These techniques help us understand a wide variety of issues, ranging from how lungs get effected by diseases like Acute Respiratory Distress Syndrome to colloidal stability of the particle stabilized emulsions.

Postdoc Project: Dilational rheology of lung surfactant inhibitors and its effects on Acute Respiratory Distress Syndrome (NIH funded)

Adviser: Dr. Joseph Zasadzinski, University of Minnesota-Twin Cities

PhD Thesis: Explaining Interfacial Behavior of a Particle Laden Interface Using Microstructure

Analysis (NSF funded)

Adviser: Dr. Gordon Christopher, Texas Tech University

Research Experiences:

As an experimentalist, I developed an interfacial shear rheometry visualization system where we can see the structural change of particles while deformation is taking place. I also examined the change in stress behavior as bulk salt and surfactant concentration changes. This study allows us to design stable particle laden interface which has extensive industrial use in oil recovery and personal products. The instrument is versatile enough to study from proteins to asphaltenes. In my postdoctoral work, I am studying dilational rheology of lung surfactant inhibitors. Because of the spherical alveolar shape, it is essential to study pulmonary surfactant monolayer in curved interface as it experiences constant area compression and expansion. We developed a version of capillary pressure tensiometer for a purely spherical interface with added visualization under confocal microscope. Initial result indicates that lipase cleaved dppc, lyso-PC, makes the interface viscous and decreases combined modulus as the concentration increases well within breathing frequency.

Teaching Interests:

As graduate student, I worked as TA for Fluid Mechanics and as an Instructor for undergraduate Thermodynamics course. After my graduation, I worked as Course Instructor for Heat transfer, Fluid Mechanics and Thermodynamics I & II for five semesters including two short summer semesters. I sincerely enjoy teaching and extremely value my 2 years of teaching experience. During this time, I conducted extra problem-solving sessions and offered flexible office hours for provide additional assistance to students. I was able to inspire numerous students to join graduate school and get involved in research projects.

Future Direction:

Going forward, I want to combine my various interfacial transport knowledge in more biological and industrial systems. I am planning on continued work on Lung Surfactant formulation and structural analysis through visualization techniques. Knowledge on extensional rheology (on microfluidic channel) from our collaboration at Minnesota can be applied in coalescence and foam stability study.

Unlike flat interface where insoluble monolayer can be easily spread out, curved interface posed a strong challenge. We are developing techniques to spread insoluble surfactants on fluid/fluid or air/fluid interface in a controlled manner. These techniques can potentially open up a pathway to solve curvature effects on complex fluid/fluid interfaces. Depositing DPPC, a major insoluble component of lung surfactant, on curved interfaces and determining the effect of essential and foreign soluble proteins and lipids essentially explain the possible mechanism of working principle of lung surfactant and their inhibitors. Employing innovative design with microscopy techniques complement the understanding of rheological and transport properties with structure information concurrently. I am also extending these techniques with modelling to solve engineering problems like better filter design, coalescence, colloidal stability, enhanced oil recovery etc.

SELECTED PUBLICATIONS

1. Barman, S., Christopher, G., “Role of Capillarity and Microstructure on Interfacial Viscoelasticity of Particle-Laden Interfaces”, J. Rheol. 60, 35 (2016)
2. Barman, S., Christopher, G., “Simultaneous Interfacial Rheology and Microstructure Measurement of Densely Aggregated Particle-Laden Interfaces Using a Modified Double Wall Ring Interfacial Rheometer”, Langmuir, 2014, 30 (32), pp 9752–9760, DOI: 10.1021/la502329s
3. Yu-Jiun Lin, Sourav Barman, Peng He, Gordon F. Christopher, Sibani Lisa Biswal, “Combined Interfacial Shear Rheology and Microstructure Visualization of Asphaltenes at Air-Water and Oil-Water Interfaces”, Journal of Rheology 62 (1), 1-10 (2018)
4. Syed E Rahmun, Nader Laal-Dehghani, Sourav Barman, Gordon F. Christopher, “Modifying interfacial interparticle forces to alter microstructure and viscoelasticity of densely packed particle laden interfaces”, Journal of Colloid and Interface Science, 536, 30-41 (2019)
5. Snoeyink, C., Barman, S., Christopher, G., “Contact Angle Distribution of Particles at Fluid Interfaces”, Langmuir, 2015, 31 (3), pp 891–897, DOI: 10.1021/la5040195
6. Zhang, Z., Barman, S., Christopher, G., “The role of protein content on the steady and oscillatory shear rheology of model synovial fluids", Soft Matter, 2014, 10, 5965-5973, DOI: 10.1039/C4SM00716F
7. Zhang, Z., Barman, S., Christopher, G., "Effect of Interfacial Viscoelasticity on the Bulk Linear Viscoelastic Moduli of Globular Protein Solutions," Physical Review E, 2013. 89
8. Snoeyink, C., Christopher, G., Barman, S., Wereley, S., “Sub-diffraction Limit Three-Dimensional Particle Tracking Velocimetry”, ASME 2013 International Mechanical Engineering Congress and Exposition IMECE 2013 (2013)
9. S. Barman, M. Ehsan, S. Bhuiyan, Low-Pressure CNG System for Diesel Power Generation, The Online Journal on Power and Energy Engineering (OJPEE), paper no. - Vol. (1) – No. (2). Web address: http://www.infomesr.org/attachments/029_10-038.pdf