Nanoparticle Delivery to Mouse Cortex

At approximately 6 months of age, mice were anesthetized with isoflurane and fixed in a stereotaxic apparatus (1900 Stereotaxic Alignment System, David Kopf Instruments, Tujunga, CA) as previously described [20 (link)]. A 33-gauge infusion cannula (Plastics One, Roanoke, VA) attached with polyurethane tubing to a Hamilton syringe (Hamilton, Reno NV) was directed at secondary motor cortex (M2. AP: 1.345, ML: +/- 0.6, DV: − 1.0). Y2(SiO₄)O-BSA-fluorescein nanoparticles (0.5 μl) or saline vehicle was infused over 3 min using a pump (GenieTouch, Kent Scientific, Torrington, CT), with the cannula left in place for an additional 1 minute to allow diffusion. Twelve mice were assigned to four groups (n = 3 per group): 3 mg/ml (one hemisphere) + saline (other), 1 mg/ml (one hemisphere) + saline (other) and sacrificed at 24 hours. For mice sacrificed at 72 hours or 9 days, they were provided bilateral injections of nanoparticles (3 mg/ml in one hemisphere + 1 mg/ml other hemisphere).