Carboxymethylated dextran cm5 sensor chip

NP binding was assessed via Surface Plasmon Resonance (SPR). All experiments were conducted at 25 °C on a Biacore Q instrument. HBS-EP running buffer (GE Healthcare) was also used throughout. A carboxymethylated dextran CM5 sensor chip (GE healthcare) was initially activated with 0.4 M EDC and 0.1 M NHS enabling chip functionalisation with 20 μg ml -1 recombinant human DLL4 Fc chimera protein (Sino Biological) via carbodiimide chemistry. DLL4 Fc was prepared in a 10 mM sodium acetate buffer at pH 4.5. Following Fc addition 1 M ethanolamine hydrochloride ( pH 8.5) was used to quench remaining NHS esters. Chip activation, functionalization and subsequent quenching solutions were permitted 7 min chip contact time with flow rate maintained at 10 μl min -1 . NPs, suspended in HBS-EP running buffer were added at the requisite concentration at 20 μL min -1 for 15 s. Chip regeneration following sample injection was achieved via the addition of sodium hydroxide solution (25 mM-50 mM) at 20 μL min -1 for 15 s. Sensorgrams obtained illustrate binding responses in absolute RU. Data presented as response relative to baseline is the difference in RU 10 s prior to and 30 s after sample addition.