Affinity for, and localization of, PEG-functionalized silica nanoparticles to sites of damage in an ex vivo spinal cord injury model

BACKGROUND: Traumatic spinal cord injury (SCI) leads to serious neurological and functional deficits through a chain of pathophysiological events. At the molecular level, progressive damage is initially revealed by collapse of plasma membrane organization and integrity produced by breaches. Consequently, the loss of its role as a semi-permeable barrier that generally mediates the regulation and transport of ions and molecules eventually results in cell death. In previous studies, we have demonstrated the functional recovery of compromised plasma membranes can be induced by the application of the hydrophilic polymer polyethylene glycol (PEG) after both spinal and brain trauma in adult rats and guinea pigs. Additionally, efforts have been directed towards a nanoparticle-based PEG application. The in vivo and ex vivo applications of PEG-decorated silica nanoparticles following CNS injury were able to effectively and efficiently enhance resealing of damaged cell membranes. RESULTS: The possibility for selectivity of tetramethyl rhodamine-dextran (TMR) dye-doped, PEG-functionalized silica nanoparticles (TMR-PSiNPs) to damaged spinal cord was evaluated using an ex vivo model of guinea pig SCI. Crushed and nearby undamaged spinal cord tissues exhibited an obvious difference in both the imbibement and accumulation of the TMR-PSiNPs, revealing selective labeling of compression-injured tissues. CONCLUSIONS: These data show that appropriately functionalized nanoparticles can be an efficient means to both 1.) carry drugs, and 2.) apply membrane repair agents where they are needed in focally damaged nervous tissue.