کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
5407743 1393229 2006 10 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
1H NMR Detection of superparamagnetic nanoparticles at 1 T using a microcoil and novel tuning circuit
موضوعات مرتبط
مهندسی و علوم پایه شیمی شیمی تئوریک و عملی
پیش نمایش صفحه اول مقاله
1H NMR Detection of superparamagnetic nanoparticles at 1 T using a microcoil and novel tuning circuit
چکیده انگلیسی

Magnetic beads containing superparamagnetic iron oxide nanoparticles (SPIONs) have been shown to measurably change the nuclear magnetic resonance (NMR) relaxation properties of nearby protons in aqueous solution at distances up to ∼50 μm. Therefore, the NMR sensitivity for the in vitro detection of single cells or biomolecules labeled with magnetic beads will be maximized with microcoils of this dimension. We have constructed a prototype 550 μm diameter solenoidal microcoil using focused gallium ion milling of a gold/chromium layer. The NMR coil was brought to resonance by means of a novel auxiliary tuning circuit, and used to detect water with a spectral resolution of 2.5 Hz in a 1.04 T (44.2 MHz) permanent magnet. The single-scan SNR for water was 137, for a 200 μs π/2 pulse produced with an RF power of 0.25 mW. The nutation performance of the microcoil was sufficiently good so that the effects of magnetic beads on the relaxation characteristics of the surrounding water could be accurately measured. A solution of magnetic beads (Dynabeads MyOne Streptavidin) in deionized water at a concentration of 1000 beads per nL lowered the T1 from 1.0 to 0.64 s and the T2∗ from 110 to 0.91 ms. Lower concentrations (100 and 10 beads/nL) also resulted in measurable reductions in T2∗, suggesting that low-field, microcoil NMR detection using permanent magnets can serve as a high-sensitivity, miniaturizable detection mechanism for very low concentrations of magnetic beads in biological fluids.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Journal of Magnetic Resonance - Volume 181, Issue 2, August 2006, Pages 181-190
نویسندگان
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