Engineers Address Key Challenge in Design of Biomaterials

Biomaterials are ubiquitous in modern medicine, from prosthetic limbs to device coatings, and hold promise for future applications like scaffolding for tissue regeneration. Biomaterial design presents a key challenge, however: applications often require materials to be both mechanically rigid (to promote strong cell adhesion) and bioactive (i.e. able to communicate specific cues to contacting cells). To date, achieving one of these features usually required sacrificing the other.

In a new paper in Advanced Functional Materials, Yale Chemical Engineering undergraduate student Connie Wu and graduate student Seyma Aslan, working with others from the groups of Paul Van Tassel of Yale SEAS and Emmanuel Pauthe of the University of Cergy-Pontoise (France), present an idea that appears to address this challenge: a thin polymer film biomaterial offering both high rigidity and bioactivity. The approach involves forming the film in the presence of sacrificial nanoparticle templates. The film is first rigidified through a chemical cross-linking procedure (similar to the way glue hardens); then, the template species are selectively dissolved, leaving behind a pore structure somewhat like that of Swiss cheese (but with much smaller holes!). These pores can then be filled with proteins able to communicate with cells, rendering the film bioactive.

The researchers' new templating approach

The new approach – part of an ongoing effort toward polymeric thin film biomaterials – achieves mechanical rigidity in conjunction with bioactivity, and, notably, allows for embedding high quantities of biological species without regard to size (previous methods were limited to lower quantities of smaller drug or protein species).

Laser scanning confocal microscopy images show cross-linked films without (left) and with (right) nanoparticle templating.

“Porous polymer films would be ideal for applications in cell-based therapies, where materials of optimal rigidity and tailored bioactivity are needed to support cellular implants or transplants,” Van Tassel states, while adding “additional research is needed, though, to determine optimal combinations of embedded bioactive species.”

Connie Wu, Seyma Aslan, Adeline Gand, Joseph S. Wolenski, Emmanuel Pauthe, Paul R. Van Tassel. Porous Nanofilm Biomaterials Via Templated Layer-by-Layer Assembly. Advanced Functional Materials. First published online: 10 AUG 2012. DOI: 10.1002/adfm.201201042. Available at http://onlinelibrary.wiley.com/doi/10.1002/adfm.201201042/abstract.