Thursday, 25 April 2013

Pulmonary Surfactant Life Imitates Art

Although a fluorescent monolayer experiment can look like a print from Merrimekko it is actually a film showing lipids, pulmonary surfactant and nanoparticles at an interface.  

What are pulmonary surfactants?

Pulmonary surfactants are needed in our lungs to aid in breathing.  The latter is a surface-active lipoprotein complex that binds to the former to do a number of things in the lung:

  • To increase pulmonary compliance or the ability for the lungs to inflate changing the volume.  The lung has a normal surface tension of 25 mN/m but at the end of expiration the pulmonary surfactant needs to decrease to near zero.  The lung surfactant takes the work away from breathing and allowing the lung to inflate easier.  This also helps to prevent the collapsing of the lung (with just lipids they might collapse on itself).
  • Aveolar size regulation.  If the pulmonary surfactants are more concentrated on small alveoli it helps to keep a constant rate of both alveoli and lung expansion.  When the alveoli are increased in size the pulmonary surfactants are spread increasing the surface tension (e.g. water is more bonded and less surfactant to separate it) slowing the expansion of the alveoli.
  • Keeping airways dry.
  • Pulmonary surfactant gives us innate immunity.  With our lungs one of the main entry points to the body (and many people get bronchitis at least once in their life) it is important to have something to prevent infection.

What are they studying in the above picture?

Since the lungs are a main entry point to the body and drugs can be fast adsorbed (as any smoker might know) scientists are developing new ways to study the lung.  To study lung surfactants you need a Langmuir Blodgett film where you can add the lipids (mostly DPPC) and the pulmonary surfactant (like SPC).  By using something like the Kibron Microtrough scientists can add carbon nanoparticles to see how they influence the the pulmonary surfactant.  As the above picture shows a snapshot of this is captured and different patterns are observed as a simulations is made by compressing the lipid layer from a gas phase (lung expansion/inhalation) to a more solid phase (lung contraction/exhalation).