Modular Surfmers with Activated Ester Function — A Colloidal Tool for the Preparation of Bioconjugative Nanoparticles

Copolymerization of methylmethacrylate (MMA) and the polymerisable surfactant (surfmer)

p

-(11(acrylamido)undecanoyloxy) — phenyldimethylsulfonium methylsulfate (AUPDS) by emulsion polymerization resulted

p

(MMAco-AUPDS) particles with a yield > 95%. The particle diameter depended on the surfmer feed concentration and was to be chosen in the range of 116 nm to 145 nm. The particle surface area per activated ester surfmer residue depended on the surfmer concentration and amounted to 0.7 nm

2

to 1.24 nm

2

. All areaper — charge values were found to be smaller then the analogous value from

cmc

measurements of an AUPDS solution in ultrapure water which was found to be 1.42 nm

2

. The protein conjugate streptavidin peroxidase (SAv-POD) was immobilized covalently on the particle surface by incubating particles in PBS buffer containing this enzyme. By addition of the enzyme substrate 3,3′,5,5′ tetramethylbenzidine (TMB) the activity of the particle-bound enzymes was determined at pH 7.2 to (5.3±0.2) mUmg

−1

. The enzyme activity was raised to (15.5±0.2) mUmg

−1

when the particles were incubated in a pH 8.0 buffer. The non-specific binding was determined to 37% when compared to the total binding by incubating particle blank samples with the same amount of SAv-POD.