Dextran amine

Nile red labeled polystyrene NPs (PS), carboxy functionalized polystyrene NPs (COOH-PS) at a mean diameter of 0.50 µm in a 1% aqueous suspension were purchased from Spherotech, Inc. (Lake Forest, IL, USA). The uorescence excitation and emission spectra maxima were all at 517 nm and 560 nm, respectively. All cell culture media were obtained from Gibco/Life Technologies. Dextran amine at MW of 6 k Da, was purchased from Creative PEGWorks (Chapel Hill, NC, USA). Other chemical reagents used for NP synthesis were purchased from Sigma-Aldrich (St Louis, MO, US). Synthesis of dextran modi ed polystyrene NPs.
COOH-PS at number of 2.5 × 10 6 and 5 nmol of Dextran amine were co-dispersed in 100 µL of 0.1 M 2-Nmorpholino ethane sulfonic acid (MES) solution. Then 0.3 mg of EDC (1-(3-Dimethylaminopropyl)-3ethylcarbodiimide hydrochloride) were twice added in, with a vortexing and incubating process of 20 minutes at ambient temperature for each time. After incubating for another 80 minutes on a rotary mixer, the product was centrifuge and remove the supernatant carefully. Then the obtained pellet was suspended in 1 mL of 0.1 M PBS containing 0.02% Tween-20.

Nile red labeled polystyrene NPs (PS), carboxy functionalized polystyrene NPs (COOH-PS) at a mean diameter of 0.50 μm in a 1% aqueous suspension were purchased from Spherotech, Inc. (Lake Forest, IL, USA). The uorescence excitation and emission spectra maxima were all at 517 nm and 560 nm, respectively. All cell culture media were obtained from Gibco/Life Technologies. Dextran amine at MW of 6k Da, was purchased from Creative PEGWorks (Chapel Hill, NC, USA). Other chemical reagents used for NP synthesis were purchased from Sigma-Aldrich (St Louis, MO, US).