Mr. Pope et al., SPECIFIC ACTIVITY OF POLYPYRROLE NANOPARTICULATE IMMUNOREAGENTS - COMPARISON OF SURFACE-CHEMISTRY AND IMMOBILIZATION OPTIONS, Bioconjugate chemistry, 7(4), 1996, pp. 436-444
Polypyrrole-based colloids with differing surface chemistries were com
pared with respect to the specific activity of immobilized antibody. M
onoclonal antibody to the alpha subunit of human chorionic gonadotropi
n (hCG) was modified by incorporation of cystamine into the Fc-carbohy
drate, followed by reduction with dithiothreitol resulting in the gene
ration of 4.5 free thiols per IgG. The reduced IgG was added to clean,
unmodified and surface-modified polypyrrole colloids. Functionalized
colloids included carboxylate-modified polypyrrole, poly[pyrrole-co-1-
(2-carboxyethyl) pyrrole]-silica composite, and amine forms of the car
boxylated colloids. The amine-functionalized colloids were subsequentl
y treated with sulfosuccinimidyl 4-(N-maleimidomethyl)cyclohexane-1-ca
rboxylate to provide thiol-reactive maleimide surface groups. Followin
g the conjugation of IgG to the colloids, bound and soluble antibody a
ctivity was quantitated using a sequentially competitive immunoassay f
or hCG, based on an automated commercial hCG kit. The results indicate
d that all forms of polypyrrole retained the equivalence of between 12
and 33 mu g of IgG activity/mg of colloidal solids, relative to the u
nmodified soluble IgG.