Figure 1.

pH dissolution test was done using UV spectrophotometer at 320 nm wavelength. Particles without (A) or with (B) surface-coating (streptavidin–biotin PEG–fibronectin) were initially fabricated in 100 µL of bicarbonate-buffered DMEM media (pH 7.5), followed by addition of DMEM media of decreasing pHs (6.5, 5.5, 4.5 and 3.5) to top up to 1 mL, prior to the turbidity measurement. Turbidity value of 0.36 indicates that particles were already formed at pH 7.5, and with decreasing pHs the particles started to dissolve, resulting in lower turbidity value until reaching close to 0 where all particles were completely dissolved.