Frog nest foams exhibit pharmaceutical foam-like properties

Abstract

Foams have frequently been used as systems for the delivery of cosmetic and therapeutic molecules; however, there is high variability in the foamability and long-term stability of synthetic foams. The development of pharmaceutical foams that exhibit desirable foaming properties, delivering appropriate amounts of the active pharmaceutical ingredient (API) and that have excellent biocompatibility is of great interest. The production of stable foams is rare in the natural world; however, certain species of frogs have adopted foam production as a means of providing a protective environment for their eggs and larvae from predators and parasites, to prevent desiccation, to control gaseous exchange, to buffer temperature extremes, and to reduce UV damage. These foams show great stability (up to 10 days in tropical environments) and are highly biocompatible due to the sensitive nature of amphibian skin. This work demonstrates for the first time that nests of the túngara frog ( Engystomops pustulosus ) are stable ex situ with useful physiochemical and biocompatible properties and are capable of encapsulating a range of compounds, including antibiotics. These protein foam mixtures share some properties with pharmaceutical foams and may find utility in a range of pharmaceutical applications such as topical drug delivery systems.

Form, function, foam: evolutionary ecology of anuran nests and nesting behaviour

“…This function may be further supported by the foam itself, which has antimicrobial properties in at least some species [83,84]. Indeed, foam nests have garnered interest in biomedical and bioengineering communities for their unique chemical and physical properties [85].…”

“…Are patterns explained by energetic trade-offs? In addition, as evidenced by examples in anurans [84,85], the compounds that animals produce for nest construction may prove to have properties that can be capitalized on for direct use in medicine and bioinspired design.…”

Adhesive properties of Aphrophoridae spittlebug foam

“…Fluidic foams in nature have fascinated researchers for centuries but are not fully understood. They occur in the sea [1][2][3], horse sweat [4] and foam nests are known from subtropical and tropical tree frog eggs [5][6][7][8][9][10][11][12], fish eggs [13,14], as well as from spittlebug nymphs [e.g. [15][16][17][18].…”

Spectral Properties of Foams and Emulsions

“…As in the case of emulsions, foams may be of natural origin, such as sea water foam [12], frog nest foam [13], beer foam and champaign [14], or artificial origin (biomedical and pharmaceutical foams) [15]. Besides the basic components, they may include nanoparticle structures such as gold or other metals [16,17].…”