- Arsonic acid-presenting superparamagnetic iron oxide for pH-responsive aggregation under slightly acidic conditions
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We report the synthesis and characterization of the arsonic acid-presenting superparamagnetic iron oxide (SPIO). We used arsonoacetic acid as the ligand for SPIOs in aqueous media. The surface modification of the SPIOs was accomplished via the ligand exchange from undecanoic acid to the carboxyl moiety of arsonoacetic acid. Consequently, the well-dispersed arsonic acid-presenting SPIOs in water were obtained. We found that the dispersion state of the arsonic acid-presenting SPIOs can be sharply regulated by pH changes in the biological significant region. The well dispersion state of the arsonic acid-presenting SPIOs can be maintained at the neutral pH region. In contrast, the arsonic acid-presenting SPIOs can sensitively form the aggregation below pH 6.1. Moreover, these dispersion states can be controlled reversibly by the pH alteration in the narrow region.
- Minehara, Hiroki,Naka, Kensuke,Tanaka, Kazuo,Narita, Asako,Chujo, Yoshiki
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- Tumor cell-specific prodrugs using arsonic acid-presenting iron oxide nanoparticles with high sensitivity
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We report the tumor cell-selective prodrugs based on the arsonic acid-presenting iron oxide nanoparticles. We synthesized the well-dispersed nanoparticles having arsonoacetic acid which is composed of the low toxic As(V) form. From the analyses of the reaction products, it is suggested that the reduction by dithiothreitol with arsonoacetic acid and the modified nanoparticles could generate the highly-toxic As(III) species. In the MTT assays, it was found that the cell viabilities of HeLaS3 and especially HepG2 were reduced in the presence of the modified nanoparticles. In contrast, a slight effect on viability was observed with primary mouse hepatocytes. The viabilities showed good agreements with the amounts of intracellular reduced glutathione concentrations. Furthermore, the valid concentrations of the modified nanoparticles for tumor-specific cytotoxicity were similar level in MRI measurements. These results indicate that arsonic acid-presenting nanoparticles should be a good platform for developing highly-sensitive tumor-specific prodrugs.
- Minehara, Hiroki,Narita, Asako,Naka, Kensuke,Tanaka, Kazuo,Chujo, Moeko,Nagao, Masaya,Chujo, Yoshiki
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- A re-investigation of arsenoacetic acid, (AsCH2COOH)n
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Detailed spectroscopic data have been obtained for arsonoacetic acid, As(CH2COOH)O3H2, and its barium and sodium salts. The X-ray crystal structure of the free acid is isomorphous with phosphonoacetic acid. Reduction gave the As(I) compound arsenoacetic acid, (AsCH2COOH)n which was shown by ESI-MS to contain cyclic species based on As-As bonds, with n mainly 3-6. The X-ray crystal structure of the hexamer was determined as the pyridine solvate and shown to have a hexacyclic As6 ring in a puckered chair conformation, with -CH 2COOH groups in equatorial sites, each H-bonded to a pyridine molecule in the lattice.
- Nicholson, Brian K.,Wilson, Peter S.,Nancekivell, Adelle
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