Fig. 1

Delta-Like 1 can be reliably biotinylated and immobilised onto streptavidin coated magnetic micro particles. DL1 can be immobilised using two distinct reaction pathways, a(i) forward, and a(ii) reverse. In the forward pathway DL1 primary amines first react with the NHS functionality of the heterobifunctionalised PEG molecule. Once reacted, streptavidin coated magnetic particles are added allowing the biotin functionality to bind with the streptavidin, resulting in iDL1. In the reverse pathway the heterobifunctionalised PEG molecule first reacts with the streptavidin coated particle, the DL1 is then added and reacts with the NHS functionality to produce iDL1 (n = 3). b DL1 could be immobilised via both pathways, the forward pathway demonstrated no effect of the DL1 solvent. The reverse pathway immobilised most DL1 per particle when DL1 was dissolved in PBS (n = 3). c Optimisation of the reverse pathway for maximum DL1 immobilisation demonstrated a rapid saturation of binding between streptavidin and the heterobifunctionalised PEG molecule during the first stage of the synthesis (n = 3) and d a 2 h optimal incubation time for the second stage (n = 3)