Category Archives: Uncategorized

DNP-NMR is becoming more popular

By Uncategorized
So I don\’t know if you are paying attention to the pageview count that is displayed on the front page to the right. Well, I do, and not too boost my ego, but because I\’m generally interested how the blog is doing and what topics are interesting for the readers.

If you follow that page counter you probably noticed that the page view count almost doubled from October to November. Now this number is a cumulative sum over the last 30 days but you can see the same behavior in the monthly counts (shown in the figure below).

I\’m super excited about that trend. It shows that the interest in DNP-NMR increases. Why the sudden increase? Well, over the last few months I was able to get more inbound links to the blog that makes the blog more visible and that increased the page view count significantly.

DNP-NMR is becoming more popular

By Uncategorized
So I don\’t know if you are paying attention to the pageview count that is displayed on the front page to the right. Well, I do, and not too boost my ego, but because I\’m generally interested how the blog is doing and what topics are interesting for the readers.

If you follow that page counter you probably noticed that the page view count almost doubled from October to November. Now this number is a cumulative sum over the last 30 days but you can see the same behavior in the monthly counts (shown in the figure below).

I\’m super excited about that trend. It shows that the interest in DNP-NMR increases. Why the sudden increase? Well, over the last few months I was able to get more inbound links to the blog that makes the blog more visible and that increased the page view count significantly.

DNP by Thermal Mixing under Optimized Conditions Yields >60‚000-fold Enhancement of 89Y NMR Signal

By Uncategorized

Lumata, L., et al., DNP by Thermal Mixing under Optimized Conditions Yields >60‚000-fold Enhancement of 89Y NMR Signal. J. Am. Chem. Soc., 2011. 133(22): p. 8673-8680

http://dx.doi.org/10.1021/ja201880y

Hyperpolarized 89Y complexes are attractive NMR spectroscopy and MR imaging probes due to the exceptionally long spin–lattice relaxation time (T1 ~ 10 min) of the 89Y nucleus. However, in vivo imaging of 89Y has not yet been realized because of the low NMR signal enhancement levels previously achieved for this ultra low-gamma nucleus. Here, we report liquid-state 89Y NMR signal enhancements over 60 000 times the thermal signal at 298 K in a 9.4 T magnet, achieved after the dynamic nuclear polarization (DNP) of Y(III) complex of 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) samples at 3.35 T and 1.4 K. The 89Y DNP was shown to proceed by thermal mixing and the liquid state 89Y NMR signal enhancement was maximized by (i) establishing the optimal microwave irradiation frequency, (ii) optimizing the glassing matrix, (iii) choosing a radical with negligible inhomogeneous line broadening contribution to the ESR linewidth, and (iv) addition of an electron T1e relaxation agent. The highest enhancements were achieved using a trityl OX063 radical combined with a gadolinium relaxation agent in water-glycerol matrix. Co-polarization of 89YDOTA and sodium [1-13C]pyruvate showed that both 89Y and 13C nuclear species acquired the same spin temperature, consistent with thermal mixing theory of DNP. This methodology may be applicable for the optimization of DNP of other low-gamma nuclei.

DNP by Thermal Mixing under Optimized Conditions Yields >60‚000-fold Enhancement of 89Y NMR Signal

By Uncategorized

Lumata, L., et al., DNP by Thermal Mixing under Optimized Conditions Yields >60‚000-fold Enhancement of 89Y NMR Signal. J. Am. Chem. Soc., 2011. 133(22): p. 8673-8680

http://dx.doi.org/10.1021/ja201880y

Hyperpolarized 89Y complexes are attractive NMR spectroscopy and MR imaging probes due to the exceptionally long spin–lattice relaxation time (T1 ~ 10 min) of the 89Y nucleus. However, in vivo imaging of 89Y has not yet been realized because of the low NMR signal enhancement levels previously achieved for this ultra low-gamma nucleus. Here, we report liquid-state 89Y NMR signal enhancements over 60 000 times the thermal signal at 298 K in a 9.4 T magnet, achieved after the dynamic nuclear polarization (DNP) of Y(III) complex of 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) samples at 3.35 T and 1.4 K. The 89Y DNP was shown to proceed by thermal mixing and the liquid state 89Y NMR signal enhancement was maximized by (i) establishing the optimal microwave irradiation frequency, (ii) optimizing the glassing matrix, (iii) choosing a radical with negligible inhomogeneous line broadening contribution to the ESR linewidth, and (iv) addition of an electron T1e relaxation agent. The highest enhancements were achieved using a trityl OX063 radical combined with a gadolinium relaxation agent in water-glycerol matrix. Co-polarization of 89YDOTA and sodium [1-13C]pyruvate showed that both 89Y and 13C nuclear species acquired the same spin temperature, consistent with thermal mixing theory of DNP. This methodology may be applicable for the optimization of DNP of other low-gamma nuclei.

2H-decoupling-accelerated 1H spin diffusion in dynamic nuclear polarization with photoexcited triplet electrons

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Negoro, M., et al., [sup 2]H-decoupling-accelerated [sup 1]H spin diffusion in dynamic nuclear polarization with photoexcited triplet electrons. J. Chem. Phys., 2010. 133(15): p. 154504-6

http://link.aip.org/link/?JCP/133/154504/1

In dynamic nuclear polarization (DNP) experiments applied to organic solids for creating nonequilibrium, high 1H spin polarization, an efficient buildup of 1H polarization is attained by partially deuterating the material of interest with an appropriate 1H concentration. In such a dilute 1H spin system, it is shown that the 1H spin diffusion rate and thereby the buildup efficiency of 1H polarization can further be enhanced by continually applying radiofrequency irradiation for deuterium decoupling during the DNP process. As experimentally confirmed in this work, the electron spin polarization of the photoexcited triplet state is mainly transferred only to those 1H spins, which are in the vicinity of the electron spins, and 1H spin diffusion transports the localized 1H polarization over the whole sample volume. The 1H spin diffusion coefficients are estimated from DNP repetition interval dependence of the initial buildup rate of 1H polarization, and the result indicates that the spin diffusion coefficient is enhanced by a factor of 2 compared to that without 2H decoupling.

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