Poly(butyl cyanoacrylate) (PBCA) nanoparticles (NPs) can penetrate blood–brain barrier providing the means for drug delivery to the central nervous system. Here, we study attachment of superoxide dismutase (SOD) and anti‐glutamate N‐methyl D‐aspartate receptor 1 (NR1) antibody to PBCA NPs with the ultimate goal to design neuroprotective therapeutics for treatment of secondary spinal cord injury. Synthesis of monodispersed, ∼200 nm‐diameter PBCA NPs was performed using polymerization at pH 2.0 with Dextran 70,000 as the stabilizer. Sulfo‐HSAB spacers were used to covalently attach SOD and NR1 antibodies to the dextran‐coated NPs. The prepared protein–NP conjugates possessed SOD activity and were capable of binding to rat cerebellar neurons. Thus, SOD and NR1 antibodies may be simultaneously attached to PBCA NPs while retaining at least a fraction of enzymatic activity and receptor‐binding ability. The conjugates showed neuroprotective efficacy in vitro with rat cerebellar cell cultures challenged by superoxide. Biotechnol. Bioeng. 2011;108: 243–252. © 2010 Wiley Periodicals, Inc.