EPR and Structural Characterization of Water-Soluble Mn2+-Doped Si Nanoparticles.
Water-soluble poly(allylamine) Mn2+-doped Si (SiMn) nanoparticles (NPs) were prepared and show promise for biologically related applications. The nanoparticles show both strong photoluminescence and good magnetic resonance contrast imaging. The morphology and average diameter were obtained through transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM); spherical crystalline Si NPs with an average diameter of 4.2 ± 0.7 nm were observed. The doping maximum obtained through this process was an average concentration of 0.4 ± 0.3% Mn per mole of Si. The water-soluble SiMnNPs showed a strong photoluminescence with a quantum yield up to 13%. The SiMnNPs had significantT1contrast with anr1relaxivity of 11.1 ± 1.5 mM-1s-1andr2relaxivity of 32.7 ± 4.7 mM-1s-1where the concentration is in mM of Mn2+. Dextran-coated poly(allylamine) SiMnNPs produced NPs withT1andT2contrast with ar1relaxivity of 27.1 ± 2.8 mM-1s-1andr2relaxivity of 1078.5 ± 1.9 mM-1s-1. X-band electron paramagnetic resonance spectra are fit with a two-site model demonstrating that there are two types of Mn2+in these NP's. The fits yield hyperfine splittings (A) of 265 and 238 MHz with significant zero field splitting (DandEterms). This is consistent with Mn in sites of symmetry lower than tetrahedral due to the small size of the NP's.
Department of Chemistry, NMR Facility and Biomedical Engineering Graduate Group, and Department of Biomedical Engineering, University of California, Davis , One Shields Avenue, Davis, California 95616, United States.
Tonya M
TM
Atkins
Department of Chemistry, NMR Facility and Biomedical Engineering Graduate Group, and Department of Biomedical Engineering, University of California, Davis , One Shields Avenue, Davis, California 95616, United States.
Jeffrey H
JH
Walton
Department of Chemistry, NMR Facility and Biomedical Engineering Graduate Group, and Department of Biomedical Engineering, University of California, Davis , One Shields Avenue, Davis, California 95616, United States.
Mani P
MP
Singh
Department of Chemistry, NMR Facility and Biomedical Engineering Graduate Group, and Department of Biomedical Engineering, University of California, Davis , One Shields Avenue, Davis, California 95616, United States.
Shreyashi
S
Ganguly
Department of Chemistry, NMR Facility and Biomedical Engineering Graduate Group, and Department of Biomedical Engineering, University of California, Davis , One Shields Avenue, Davis, California 95616, United States.
Oliver
O
Janka
Department of Chemistry, NMR Facility and Biomedical Engineering Graduate Group, and Department of Biomedical Engineering, University of California, Davis , One Shields Avenue, Davis, California 95616, United States.
Angelique Y
AY
Louie
Department of Chemistry, NMR Facility and Biomedical Engineering Graduate Group, and Department of Biomedical Engineering, University of California, Davis , One Shields Avenue, Davis, California 95616, United States.
Susan M
SM
Kauzlarich