RESUMEN
Reported are the formation of rough particulate films from cross-linked diblock copolymer vesicles and nanotubes and the wetting properties of the resultant films. The diblock copolymers used were F66M200 and F95A135, where the subscripts denote the repeat unit numbers, whereas M, A, and F denote poly(2-cinnamoyloxyethyl methacrylate), poly(2-cinnamoyloxyethyl acrylate), and poly(2,2,2-trifluoroethyl methacrylate), respectively. The precursory polymers to F66M200 and F95A135 were prepared by atom transfer radical polymerization. In 2,2,2-trifluoroethyl methacrylate (FEMA), a selective solvent for F, vesicles and tubular micelles were prepared from F66M200 and F95A135, respectively. Photo-cross-linking the M and A blocks of these aggregates yielded hollow nanospheres and nanotubes bearing F coronal chains. These particles were dispersed into CH2Cl2/methanol, where CH2Cl2 was a good solvent for both blocks and methanol was a poor solvent for F. Casting CH2Cl2/methanol dispersions of these particles yielded films consisting of hierarchically assembled diblock copolymer nanoparticles. For example, the hollow nanospheres fused into microspheres bearing nanobumps after being cast from CH2Cl2/methanol at methanol volume fractions of 30 and 50%. The roughness of these films increased as the methanol volume fraction increased. The films that were cast at high methanol contents were superhydrophobic, possessing water contact angles of â¼160° and water sliding angles of â¼3°.
RESUMEN
BACKGROUND: Immunological memory is the basis for vaccination. Currently, the longitudinal profiles of antibody responses in recovered severe acute respiratory syndrome (SARS) patients have not been fully characterized. METHODS: In this study we sequentially followed up 19 recovered SARS patients over a 3-y period in order to characterize the dynamic changes in antibody responses against viral components in detail. In addition, 4 blood samples were obtained at month 60. RESULTS: We found that immunoglobulin G (IgG) antibodies and their neutralizing activities decreased throughout the entire phase of the study. For IgG antibodies in the 3rd y, the positive rate of whole-virus-specific antibodies was 42%, which was tested with commercial kits at 1/10 dilution of the sera. In comparison, the positive rate of spike (S) protein-specific antibodies was 100%, which was tested by spike protein-based ELISA at 1/100 dilution; 4 samples at month 60 were included. The average optical density (OD) reading of nucleocapsid (N) protein-specific antibodies fell dramatically between month 3 and month 12, and it decreased gradually at low levels that were a little higher than the cut-off value from month 12. For neutralizing antibodies, neutralizing activity was detectable in 89% of recovered patients in the 3rd y. S protein-specific IgG levels (r = 0.717) correlated better with neutralizing activity than SARS coronavirus-specific IgG levels (r = 0.571). CONCLUSIONS: These systematic findings provide valuable information on natural humoral memory responses, and the data will be helpful for understanding the pathogenesis of SARS coronavirus infection and for the rational design of vaccines.
