[1] Duke Univ, Dept Biomed Engn & Surg, Durham, NC 27708 USA
[2] Johns Hopkins Univ, Dept Mat Sci & Engn, Baltimore, MD 21218 USA
[3] Nanyang Technol Univ, Sch Chem & Biomed Engn, Singapore 637459, Singapore
[4] Johns Hopkins Univ Hosp, Dept Neurol, Baltimore, MD 21287 USA
[5] Johns Hopkins Univ Hosp, Dept Neurosci, Baltimore, MD 21287 USA