Fig. 2
Al accumulation on the bare cells and silica-coated cells. RBCs were exposed to 100 µM AlCl3 solution at pH 4.5 for 1 h. A Al concentration in the solution was determined by the colorimetric method using pyrocatechol violet before and after the treatment, respectively, to deduce the amount of Al adsorption (n = 3). The distribution of Al in the bare cells (C) and the silica-coated cells (D) was observed using LSCM (n = 15). A relative fluorescence intensity of the Morin stain was calculated (B). Bar represents mean ± SE (n = 20). Different lowercase letters indicate significant differences at p < 0.05 between treatments (Duncan’s test). Scale bars = 25 μm. After Al treatment, RBCs with silica-coat (+Si–Al) were centrifuged and dried for X-ray photoelectron spectroscopy (XPS). The Si2p (E) region was decomposed into two components at 102.65 and 104.0 eV, and the Al2p (F) region was at 73.1 and 74.5 eV, suggesting the presence of aluminum silicate hydroxide at the cell wall surface [30, 31]