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Isoindoline nitroxide-containing porphyrins were synthesized by the reaction of 5-phenyldipyrromethane and 5-(4′-nitrophenyl)-dipyrromethane with 5-formyl-1,1,3,3-tetramethylisoindolin-2-yloxyl using the Lindsey method. These spin-labeled porphyrins were further characterized by MS, UV, FTIR, 1H-NMR, cyclic voltammetry, electron paramagnetic resonance (EPR), and fluorescence spectroscopy. The electrochemical assay demonstrated that these isoindoline nitroxides-containing porphyrins had similar electrochemical and redox properties as 5-carboxy-1,1,3,3-tetramethylisoindolin-2-yloxyl. Electron paramagnetic resonance test exhibited these porphyrins possessed the hyperfine splittings and characteristic spectra of isoindoline nitroxides, with typical nitroxide g-values and nitrogen isotropic hyperfine coupling constants. Fluorescence spectroscopy revealed that these porphyrins indicated fluorescence suppression characteristic of nitroxide-fluorophore systems. Moreover, their reduced isoindoline nitroxide-containing porphyrins eliminated the fluorescence suppression and displayed strong fluorescence. Thus, these isoindoline nitroxide-containing porphyrins may be considered as the potential fluorescent and EPR probes. [ABSTRACT FROM AUTHOR]

A water-soluble fullerenol containing porphyrin and isoindoline nitroxide groups APTSPP-C60(OH)10-(TMIO)3was synthesized by the incorporation of 5-(4-amino-phenyl)-10,15,20-tris(4-sulfonatophenyl)-porphyrin (APTSPP) as a tumor-targeting group and 5-formyl-1,1,3,3-tetramethylisoindolin-2-yloxyl (FTMIO) into fullerenol C60(OH)11. This nonmaterial was further characterized by FT-IR, UV, MS, TEM, fluorescence, etc. and its properties in vitro were also evaluated. Electrochemical experiments indicated that APTSPP-C60(OH)10-(TMIO)3retained similar electrochemical properties and redox reaction mechanisms as 5-carboxy-1,1,3,3-tetramethylisoindolin-2-yloxyl (CTMIO). Electron paramagnetic resonance (EPR) spectra of APTSPP-C60(OH)10-(TMIO)3exhibited the hyperfine splittings and characteristic spectra of CTMIO, with typical nitroxide g-values and nitrogen isotropic hyperfine coupling constants. In vitro cytotoxicity assay showed APTSPP-C60(OH)10-(TMIO)3possessed low cytotoxicities to human renal tubular epithelial 293T cells and HepG-2 cells. Therefore APTSPP-C60(OH)10-(TMIO)3may be considered as a potential candidate for novel biological spin probe using EPR spectroscopy. [ABSTRACT FROM AUTHOR]

Three fullerene isoindoline nitroxides N-methyl-3,4-fulleropyrrolidine-2-spiro-5′- (1′,1′,3′,3′-tetramethylisoindolin-2′-yloxyl), (C60-(TMIO)m, and C70-(TMIO)n) were synthesized by the covalent bonding of 5-formyl-1,1,3,3-tetramethyl isoindolin-2-yloxyl to the fullerenes C60and C70. Significantly, the X-ray photoelectron spectra indicated the characteristic N 1s signals of NO.at 402 eV. The atomic force microscope morphologies showed that the average particle sizes of C60-(TMIO)mand C70-(TMIO)nwere 38 and 15 nm. The electrochemical experiments indicated that fullerene bound isoindoline nitroxides retained similar electrochemical properties and redox reaction mechanisms as the parent nitroxides. The electron paramagnetic resonance spectra of the fullerene isoindoline nitroxides all exhibited the hyperfine splittings and characteristic spectra of tetramethyl isoindoline nitroxides, with typical nitroxide g-values and nitrogen isotropic hyperfine coupling constants. Therefore, these fullerene isoindoline nitroxides may be considered as potential candidates for novel biological spin probes using electron paramagnetic resonance spectroscopy. [ABSTRACT FROM PUBLISHER]

Water-soluble polyaspartamide isoindoline nitroxides 5-(4′-aminophenyl)-10,15,20-tris (4′-sulfonatophenyl) porphyrin, trisodium salt–poly[α,β-N-(2-hydroxyethyl)-l-aspartamide]–5-carboxy-1,1,3,3-tetramethylisoindolin-2-yloxyl were synthesized by the incorporation of 5-(4′-aminophenyl)-10,15,20-tris(4′-sulfonatophenyl) porphyrin, trisodium salt, as a tumor-targeting group, and 5-carboxy-1,1,3,3-tetramethylisoindolin-2-yloxyl into poly[α,β-N-(2-hydroxyethyl)-l-aspartamide]. These compounds were characterized, and the in vitro properties were evaluated. The polyaspartamide isoindoline nitroxides had higher relaxation effectiveness and had greater toxicity to HeLa cells than that of 5-carboxy-1,1,3,3-tetramethylisoindolin-2-yloxyl. The polyaspartamide isoindoline nitroxides retained similar electrochemical properties and redox reaction mechanisms as the parent nitroxides. The electron paramagnetic resonance spectra of polyaspartamide isoindoline nitroxides exhibited characteristic hyperfine electron paramagnetic resonance spectra of tetramethyl isoindoline nitroxides, with typical nitroxide g-values and nitrogen isotropic hyperfine coupling constants. Therefore, the water-soluble 5-(4′-aminophenyl)-10,15,20-tris(4′-sulfonatophenyl) porphyrin, trisodium salt–poly[α,β-N-(2-hydroxyethyl)-l-aspartamide]–5-carboxy-1,1,3,3-tetramethylisoindolin-2-yloxyl is considered to be a novel potential spin probe for electron paramagnetic resonance. [ABSTRACT FROM PUBLISHER]