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NMR Studies of Loaded Microspheres
Proceedings of the 59th Experimental Nuclear Magnetic Resonance Conference (2019, Orlando, FL)
  • Ming Huang
  • Sisi Chen
  • Rex E. Gerald, II
  • Jie Huang, Missouri University of Science and Technology
  • Klaus Woelk, Missouri University of Science and Technology
Abstract

Porous-wall hollow glass microspheres (PWHGMs) are a novel form of glass materials that consist of 1-μm-thick porous silica shells, 20-100 μm in diameter, with a hollow cavity in the center. Utilizing the central cavity for material storage and the porous walls for controlled release is a unique combination that renders PWHGMs a superior vehicle for targeted drug delivery. In this study, NMR spectroscopy was used to characterize PWHGMs for the first time. A vacuum-based loading system was developed to load PWHGMs with various compounds followed by a washing procedure that uses solvents immiscible with the target material. Immiscible binary model systems (chloroform/water, n-dodecane/water), as well as the hydrolysis of isopropyl acetate, were investigated to obtain NMR evidence for material loading into PWHGMs and their subsequent release to the surrounding solutions. The NMR peaks of the loaded materials were distinguishable from the NMR peaks of the materials in the surrounding solution. The formation of the reaction product isopropanol provided evidence of encounters of isopropyl acetate in the microspheres and concentrated H2SO4 added to the surrounding solution. Also, microspheres loaded with H2O were suspended in D2O and monitored to obtain quantitative release kinetics of H2O encapsulated in PWHGMs. A five-parameter double-exponential curve fit of experimental signal intensity data as a function of time indicated two release rates for H2O encapsulated in PWHGMs with time constants of 18 - 20 minutes and 160 minutes. The results demonstrate that NMR is a particularly useful tool to study developments and applications of PWHGMs in targeted drug delivery.

Meeting Name
59th Experimental Nuclear Magnetic Resonance Conference (2019: Apr. 29-May 4, Orlando, FL)
Department(s)
Electrical and Computer Engineering
Second Department
Chemistry
Research Center/Lab(s)
Intelligent Systems Center
Document Type
Article - Conference proceedings
Document Version
Citation
File Type
text
Language(s)
English
Rights
© 2018 SPIE, All rights reserved.
Publication Date
5-4-2018
Publication Date
04 May 2018
Citation Information
Ming Huang, Sisi Chen, Rex E. Gerald, Jie Huang, et al.. "NMR Studies of Loaded Microspheres" Proceedings of the 59th Experimental Nuclear Magnetic Resonance Conference (2019, Orlando, FL) (2018)
Available at: http://works.bepress.com/klaus_woelk/75/