* Corresponding authors

^a Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
E-mail: hammond@mit.edu

^b The David H. Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
E-mail: belcher@mit.edu

^c Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA

^d Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA

^e Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA