Postdoctoral Fellow

Brief Description of the Position:
The Zasadzinski group is looking to hire a postdoctoral fellow to work on an ongoing NIH
sponsored project examining the effects of interfacial rheology on the development of acute
respiratory distress syndrome (ARDS). ARDS is a pulmonary disease with a 40% mortality rate
that effects over 300,000 people in the US each year. The underlying causes of the disease are not
well understood, but we believe that ARDS may be explained by changes to the interfacial
properties of the lung surfactant (LS) that occur during lung inflammation. The Laplace pressure
difference, DP = 2g/R, between the inside and outside the curved, air-liquid interface in the alveoli
suggests that the interconnected alveoli in the lung of different radii, R, are at best metastable if
the surface tension, g is constant. Any variation in R would cause DP to increase in the smaller
alveolar and decrease in the larger alveoli, which is known as the “Laplace Instability.” However,
healthy lung surfactant causes g to decrease with decreasing alveolar interfacial area sufficiently
to arrest the Laplace Instability. The variation of surface tension with interfacial area is known as
the dynamic dilatational modulus, 𝜀(𝜔) = 𝐴(𝜔)(𝜕𝛾⁄𝜕𝐴), in which w is the breathing frequency.
If the amount or quality of lung surfactant changes during disease, the dilatational modulus and
surface tension can change, and if 𝜕*𝛾
,𝑅- 𝜕𝑅 = (2𝜀 − 𝛾)
, ,𝑅! < 0 or (2𝜀 − 𝛾) < 0, the Laplace

Instability will be triggered, which can cause the alveoli to collapse and fill with fluid, one of the
symptoms of Acute Respiratory Distress Syndrome (ARDS). Hence, the dilatational modulus, and
how it depends on monolayer composition, morphology, interfacial curvature, and the dynamic
changes in lung area are essential factors controlling lung stability. Lysolipid concentrations,
produced by degradation of bacterial and/or viral lipids by phospholipase A2 during the immune
response, increase during lung inflammation. Preliminary work in the Zasadzinski group has
shown that these lysolipids increase 𝛾 while simultaneously decreasing 𝜀. A unique custom built
confocal microscope/capillary pressure microtensiometer is available in the Zasadzinski lab to
study the interfacial dilatational and shear rheology of LS and develop structure-function
relationships in LS monolayers by simultaneous imaging of the monolayer with confocal
microscopy. We actively collaborate on interfacial adsorption dynamics with Dr. David Morse and
Dr. Cari Dutcher of the U of M, Todd Squires at UCSB, and we have access to natural and synthetic
lung surfactants and proteins prepared by Alan Waring at UCLA. We hope to elucidate the
underlying cause of ARDS by visualizing the interface during bubble expansion and compression.

The position requires a Ph. D. in chemical or biochemical engineering, mechanical
engineering, physics, biophysics, chemistry, or a related field. As a salaried Postdoctoral Associate,
you qualify for health, dental and life insurance programs. This appointment provides vacation
benefits as described here https://policy.umn.edu/hr/academicvacation. You can review a summary
of benefits available to you in this position at the following link: at https://hr.umn.edu/Benefits/UM-
Employment-Benefits. Should you have questions about your benefits, please contact
[email protected] or by calling 612-624-8647.