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Jiang G Pichaandi J Johnson NJ Burke RD van Veggel FC 《Langmuir : the ACS journal of surfaces and colloids》2012,28(6):3239-3247
Ligands on the nanoparticle surface provide steric stabilization, resulting in good dispersion stability. However, because of their highly dynamic nature, they can be replaced irreversibly in buffers and biological medium, leading to poor colloidal stability. To overcome this, we report a simple and effective cross-linking methodology to transfer oleate-stabilized upconverting NaYF(4) core/shell nanoparticles (UCNPs) from hydrophobic to aqueous phase, with long-term dispersion stability in buffers and biological medium. Amphiphilic poly(maleic anhydride-alt-1-octadecene) (PMAO) modified with and without poly(ethylene glycol) (PEG) was used to intercalate with the surface oleates, enabling the transfer of the UCNPs to water. The PMAO units on the phase transferred UCNPs were then successfully cross-linked using bis(hexamethylene)triamine (BHMT). The primary advantage of cross-linking of PMAO by BHMT is that it improves the stability of the UCNPs in water, physiological saline buffers, and biological growth media and in a wide range of pH values when compared to un-cross-linked PMAO. The cross-linked PMAO-BHMT coated UCNPs were found to be stable in water for more than 2 months and in physiological saline buffers for weeks, substantiating the effectiveness of cross-linking in providing high dispersion stability. The PMAO-BHMT cross-linked UCNPs were extensively characterized using various techniques providing supporting evidence for the cross-linking process. These UCNPs were found to be stable in serum supplemented growth medium (37 °C) for more than 2 days. Utilizing this, we demonstrate the uptake of cross-linked UCNPs by LNCaP cells (human prostate cancer cell line), showing their utility as biolabels. 相似文献
153.
Cleaves HJ Michalkova Scott A Hill FC Leszczynski J Sahai N Hazen R 《Chemical Society reviews》2012,41(16):5502-5525
Life is believed to have originated on Earth ~4.4-3.5 Ga ago, via processes in which organic compounds supplied by the environment self-organized, in some geochemical environmental niches, into systems capable of replication with hereditary mutation. This process is generally supposed to have occurred in an aqueous environment and, likely, in the presence of minerals. Mineral surfaces present rich opportunities for heterogeneous catalysis and concentration which may have significantly altered and directed the process of prebiotic organic complexification leading to life. We review here general concepts in prebiotic mineral-organic interfacial processes, as well as recent advances in the study of mineral surface-organic interactions of potential relevance to understanding the origin of life. 相似文献
154.
YP Zhu M Lian FC Jia MC Liu JJ Yuan QH Gao AX Wu 《Chemical communications (Cambridge, England)》2012,48(72):9086-9088
An I(2) promoted domino protocol was developed to construct 2-acylbenzothiazoles from simple and readily available aromatic ketones/unsaturated methyl ketones and o-aminobenzenethiols. The reaction proceeded smoothly under metal-free and peroxide-free conditions. 相似文献
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Aihara H Alston-Garnjost M Avery RE Barker AR Bauer DA Bay A Belcinski R Bingham HH Bloom ED Buchanan CD Caldwell DO Chao HY Chun SB Clark AR Cowan GD Crane DA Dahl OI Daoudi M Derby KA Eastman JJ Eberhard PH Edberg TK Eisner AM Erné FC Fairfield KH Fridman A Godfrey G Hauptman JM Ho C Hofmann W Kamae T Kenney RW Khacheryan S Kofler RR Lambert DJ Langeveld WG Layter JG Lin WT Linde FL Loken SC Lu A Lynch GR Lys JE Madaras RJ Magnuson BD Marsiske H Masek GE Mathis LG Maxfield SJ Miller ES 《Physical review D: Particles and fields》1991,43(1):29-33
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