Red blood cells (RBCs) during microcirculation, aging and storage, lose N-acetylneuraminic acid (NANA) and other biomaterials thereby altering cell structures, some properties and functions. Such cell damage very likely underlies the serious adverse effects of blood transfusion. However, a controversy has remained since 1961–1977 as to whether with aging, the RBCs, suffering loss of NANA, do have a decreased charge density. Any correlation between the changes in the cell properties with cell aging is also not clear. Therefore, to remove the ambiguity and uncertainty, we carried out multiparameteric studies on Percoll fractions of blood of 38 volunteers (lightest-young-Y-RBCs, densest-old-O-RBCs, two middle fractions).We found that there were striking differences between the properties of Y-RBCs and O-RBCs. The ζ-potential of Y-RBCs decreased gradually with aging. Studies in parallel on RBC fractions incubated with both positively charged quantum dots and Sambucus Nigra-fluorescein isothiocyanate (FITC) along with their ζ-potentials provide for the first time direct visual evidence about the lesser amount of charge density and NANA on O-RBCs, and a collinear decrease in their respective ζ-potentials. Close correlation was found between the surface charge on an aging RBC and its structure and functions, from the cell morphology, the membrane deformability to the intracellular Hb structure and oxidation ability. This quantitative approach not only clarifies the picture but also has implications in biology and medicine.

Raman confocal microscopy, including the techniques of point Raman spectra, line mapping, 2D mapping, and time-dependent spectrum monitoring performed with 514.5 nm excitation light, was used in a comparative study on the distribution and oxidation states of hemoglobin (Hb) in young and old mature erythrocytes. It is demonstrated that in contrast to the homogeneous distribution of the Hb in young cells, there are more Hb distribution around the cell membrane in old erythrocyte. The proteins exhibit some extent of aggregation and conformational change, present less ability of oxidation, and lower oxygenation speed than the Hb in young erythrocytes. Our results also provide the first direct evidence of some intermediate oxygenated states of Hb between the two fully oxygenated (R) and deoxygenated (T) states in living erythrocyte, and give detail information about the conformational change of the intracellular Hb with time during the reoxygenation process.

It is of great challenge to develop the effective and stable sorbents for 99TcO4 – sequestration from alkaline nuclear waste. In this work, we demonstrate a general strategy for the design of poly­(ionic liquids)@COF composites, via in situ polymerization of imidazolium-based ionic liquids (ILs) encapsulated in the pores of covalent–organic frameworks (COFs). With regard to the polyILs@COF composites, the cross-linking polyILs endow the alkali-stable COF framework with numerous ionic fillers as the anion-exchange sites. Compared with the pristine COF, the optimized composite not only enhances the alkali resistance but also shows the excellent ReO4 – (a surrogate of 99TcO4 –) removal performances of fast exchange kinetics, high uptake capacity, superior selectivity, and good reusability, even in simulated high-level waste stream at the U.S. Savannah River Site (a typical alkaline nuclear waste). The alkaline stability and selectivity of the optimized composite can be further verified by the density functional theory (DFT) calculations, indicating its unique chemical recognition of TcO4 – over other anions with higher charge density.

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