Tracing Carbon Nanotubes (CNTs) in Rat Peripheral Nerve Regenerated with Conductive Conduits Composed of Poly(lactide--glycolide) and Fluorescent CNTs.

Nerve regeneration can be promoted using nerve guide conduits (NGCs). Carbon nanotubes (CNTs) are often used to prepare conductive NGCs, however, the major concern for their applications is the final location of the implanted CNTs in vivo. Herein, photoluminescent multiwalled CNTs (MWCNTs) were prepared and electrospun with poly(lactide--glycolide) (PLGA), followed by shaping into multichannel NGCs for repairing of injured rat sciatic nerve, thereby the distribution of CNTs in vivo could be detected via bioimaging. Photoluminescent MWCNTs (MWCNT-FITC) were prepared by functionalization with poly(glycidyl methacrylate) (PGMA) and fluorescein-isothiocyanate-isomer I (FITC) subsequently. The conductivity of the PLGA/MWCNT-FITC fibers was approx. 10 S/cm at 3 wt % MWCNTs. Compared with PLGA fibers, Schwann cells on PLGA/MWCNT-FITC fibers matured at a faster rate, accordingly, nerve regeneration was promoted by the PLGA/MWCNT-FITC NGC. With a confocal laser scanning microscope and small-animal imaging system, the location of MWCNTs was detected. Alongside the degradation of PLGA, MWCNTs intended to aggregate and were entrapped in the regenerated nerve tissue without migrating into surrounding tissues and other organs (liver, kidneys, and spleen). This study provides a useful characterization method for MWCNTs and the guidance for in vivo applications of MWCNTs in tissue engineering.