Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0267964 (PAA)
 2,561 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Gold nanoclusters protected by 3-mercaptopropionic acid (MPA-Au nanoclusters) were prepared by citrate-reduction of hydrogen tetrachloroaurate(III) in the presence of sodium 3-mercaptopropionate. Color of the dispersions of MPA-Au nanoclusters changed from red to purple by addition of hydrochloric acid and returned from purple to red by addition of an aqueous sodium hydroxide solution. This reversible response can be attributed to synchronized changes between dispersion and ordering of MPA-Au nanoclusters, determined by transmission electron microscopy. Gold nanoclusters protected by poly(acrylic acid) (PAA-Au nanoclusters) were prepared by UV irradiation of an aqueous solution of hydrogen tetrachloroaurate(III) in the presence of poly(sodium acrylate). The pH-dependent spectral change observed for MPA-Au was not observed for PAA-Au. UV-Vis absorption spectra of colloidal dispersions of PAA-Au nanoclusters after addition of hydrochloric acid and an aqueous sodium hydroxide solution were in good agreement with each other, suggesting the stability of PAA-Au nanoclusters to pH change.
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PMID:pH-dependent color change of colloidal dispersions of gold nanoclusters: effect of stabilizer. 1501 Sep 39

Poly(amido amine) (SS-PAA) random and block copolymers having bioreducible disulfide bonds in the main chain and amino groups with distinctly different basicity in the side chain were designed and synthesized by Michael addition polymerization between N, N'-cystaminebisacrylamide (CBA) and two amine monomers, i.e., histamine (HIS) and 3-(dimethylamino)-1-propylamine (DMPA). Copolymers containing variable HIS/DMPA ratios show higher ability to bind DNA than p(CBA-HIS) homopolymer and condense DNA into the polyplexes with particle sizes (<150 nm) that are smaller than polyplexes of p(CBA-HIS) ( approximately 220 nm). The buffer capacities of the copolymers increase with increasing HIS/DMPA ratio. These copolymers are able to transfect COS-7 cells in vitro with efficiencies that increase with increasing HIS/DMPA ratio. The random and block copolymers at a HIS/DMPA ratio of 70/30 combines optimal DNA condensation capability and buffer capacity, thereby inducing higher transfection efficiency in the absence and presence of serum as compared to p(CBA-HIS) homopolymer. Moreover, random and block copolymers show a similar transfection capacity, but both have higher capacity than the physical mixtures of p(CBA-HIS) and p(CBA-DMPA) homopolymers. XTT assay reveals that the polyplexes of the SS-PAA copolymers have essentially low cytotoxicity when the highest transfection activity is observed.
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PMID:Random and block copolymers of bioreducible poly(amido amine)s with high- and low-basicity amino groups: study of DNA condensation and buffer capacity on gene transfection. 1772 1