Abstract
Crystallization pathways are essential to various industrial, geological, and biological processes. In nonclassical nucleation theory, prenucleation clusters (PNCs) form, aggregate, and crystallize to produce higher order assemblies. Microscopy and X-ray techniques have limited utility for PNC analysis due to the small size (0.5-3 nm) and time stability constraints. We present a new approach for analyzing PNC formation based on 31P nuclear magnetic resonance (NMR) spin counting of vitrified molecular assemblies. The use of glassing agents ensures that vitrification generates amorphous aqueous samples and offers conditions for performing dynamic nuclear polarization (DNP)-amplified NMR spectroscopy. We demonstrate that molecular adenosine triphosphate along with crystalline, amorphous, and clustered calcium phosphate materials formed via a nonclassical growth pathway can be differentiated from one another by the number of dipolar coupled 31P spins. We also present an innovative approach for examining spin counting data, demonstrating that a knowledge-based fitting of integer multiples of cosine wave functions, instead of the traditional Fourier transform, provides a more physically meaningful retrieval of the existing frequencies. This is the first report of multiquantum spin counting of assemblies formed in solution as captured under vitrified DNP conditions, which can be useful for future analysis of PNCs and other aqueous molecular clusters.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 7084-7094 |
| Number of pages | 11 |
| Journal | Journal of Physical Chemistry Letters |
| Volume | 15 |
| Issue number | 27 |
| DOIs | |
| State | Published - Jul 11 2024 |
Funding
M.S.N. and S.H. thank Alexej Jerschow for helpful discussions about the feasibility of MQ-SC under DNP conditions and Manisha Patel for being a part of the Quantum Brain team and supporting experimental work of this study. M.S.N. and S.H. also thank Dennis Kurzback and Ludovica Martina Epasto for extensive discussion about mSBF reproduction, exchanging protocols, and comparing results. The authors learned that the process is inherently delicate and complex, needing a better mechanistic understanding. M.S.N., J.S.S., and R.C. thank the Heising-Simons Foundation for support of the study of ACP formation. M.S.N. thanks the National Science Foundation (NSF) Graduate Research Fellowship under Grant 1650114 for support, and R.C. and S.J. thank the NSF for support of DNP method developments under Grant CHE CMI 2004217. S.H. was also supported by the National Institutes of Health under Grant R35GM136411 for the DNP studies of biomolecules. This work made use of the MRL Shared Experimental Facilities supported by the MRSEC Program of the NSF under Grant DMR 1720256, a member of the NSF-funded Materials Research Facilities Network. M.S.N., J.S.S., and S.H. acknowledge the support of NSF Major Research Instrumentation award, MRI-1920299, for solution magnetic resonance instrumentation.
ASJC Scopus subject areas
- General Materials Science
- Physical and Theoretical Chemistry