Exploiting the potential of foam nests produced by Engystomops pustulosus

  • Sarah Brozio

Student thesis: Doctoral Thesis


Foams are formed of air trapped in a solid or liquid creating cell-like structures. They are attracting attention in the pharmaceutical industry as potential drug delivery systems. The Tungara frog, Engystomops pustulosus, constructs foam nests which act as incubation chambers protecting the developing eggs and tadpoles from predation and environmental damage. This foam is highly stable and does not harm the eggs, sperm ortadpoles. Amphibians produce a range of proteins and peptides that may have pharmaceutical utility, and this is a growing area of research. This work investigated the potential of the foam-nest produced by E. pustulosus as a novel drug release system. Bioinformatics were used to gain insight in to the six proteins that comprise the foam, the Ranaspumins (RSN), highlighting that many of the proteins have homology to uncharacterised amphibian proteins and that one protein, RSN-2, remains a unique surfactant protein. The foam was characterised as pharmaceutical foam revealing that it is low density, resistant to shear and is non-toxic to HaCaT cells. The foams drug release capabilities were tested by loading the foam with model hydrophilic and hydrophobic dyes and measuring their release profiles. The foam delivery potential was then tested with an antibiotic, rifampicin, demonstrating that the foam could successfully release an active drug with a release profile that shows promise for drug delivery. This work developed methodology to produce a synthetic foam using recombinant RSNs. A universal method was developed to clone each rsn gene into aplasmid vector which could be induced to overexpress each RSN in the bacterium Escherichia coli and subsequent purification.All six RSNs were cloned and overexpressed, but only RSN-2 could be purified successfully. The recombinant RSN-2 was investigated for its effect on mammalian and bacterial cells and was used to produce a stable foam, with release experiments showing that RSN-2 can be used to create a foam drug delivery system as the first step towards a completely synthetic foam. Overall, this work demonstrates that E. pustulosus foam has great potential as a drug release system.
Date of Award26 Sep 2018
Original languageEnglish
Awarding Institution
  • University Of Strathclyde
SponsorsUniversity of Strathclyde, NSF Health Sciences Ltd & EPSRC (Engineering and Physical Sciences Research Council)
SupervisorPaul Hoskisson (Supervisor) & Dimitrios Lamprou (Supervisor)

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