Figure 1.
Allyl-terminated polyethylene glycol was modified by reaction with succinic anhydride. 4-dimethylaminopyridine (DMAP) catalyzes this reaction. Subsequently the allyl functionality is reacted with a thiol-containing siloxane molecule, by thiol-ene click chemistry, which yields the final carboxylic acid-terminated PEG-siloxane.
Figure 2.
The available carboxylic acid groups are activated with EDC-NHS chemistry. The resulting NHS ester reacts with amine groups of the antibody in a MES buffer. Finally the particles are recovered from the supernatant by a magnetic column.
Figure 3.
Nanoparticle-antibody coupling results.
If EDC-NHS coupling reagents are added to the mixture of NP and antibodies, slightly more proteins are retained on the NP. This indicates that a small level of crosslinking occurs. When a large amount of antibodies (without coupling reagents) is added, no significant difference is observed, which shows that only a hard corona remains on the NP after washing. All error bars are shown as the percentage error on the total value.
Figure 4.
A multimode optical fiber was coated with a gold layer, a self-assembling monolayer (SAM) and the appropriate antigen (PAI-1), as shown in the inset. The SPR shift caused by the nanoparticles, coated with MA-33H1F7 or MA-T12D11, is clearly visible.