What is the mechanism behind the foam formation? Why should bubbles be generated that then should burst?
The air/liquid interface makes the foam stabilize, forming a fibril network around the cells. The air bubbles are not natural in vivo, and the foaming step is just to form the 3D network and the bubbles should disappear. The silk with cells assembles into a thin film around each bubble. The smaller bubbles merge into bigger bubbles that disperse (within 1-4 days) and the foam transforms into a stabilized, multi-layered 3D network with uniformly integrated cells between the microfibers. Mechanical interruption (like puncture) is not recommended. The Biosilk network support cell growth in a 3D environment surrounded with nutrition from all dimensions.