Quantitative chemical mapping of sodium acrylate- and N-vinylpyrrolidone-enhanced alginate microcapsules.
Alginate microcapsules enclosing recombinant cells secreting therapeutic products have been used successfully to treat several murine models of human diseases. The mechanical and chemical properties of these alginate capsules can be improved by the addition and in situ photo-polymerization of sodium acrylate and N-vinylpyrrolidone in the alginate capsule. The purpose of this modification was to form additional covalent cross-links. In this work we have used scanning transmission X-ray microscopy (STXM) to probe the nature and location of the chemical modifications in the modified capsules by comparison with unmodified capsules. Analysis of X-ray image sequences and selected area spectra has been used to map the calcium gradient in capsules, to identify the presence of polyacrylate throughout the capsules and the localization of poly-N-vinylpyrrolidone in the outer regions of the alginate capsules. The differences in the spatial distributions of these species have led to better understanding of the chemical modifications that provide a mechanically more stable capsule structure.
Araki
Tohru
T
Department of Chemistry, McMaster University, Hamilton, Ontario, Canada.
Hitchcock
Adam P
AP
Shen
Feng
F
Chang
Patricia L
PL
Wang
Maggie
M
Childs
Ronald F
RF
D000179:Acrylates / Q000737:chemistry*; D000464:Alginates / Q000737:chemistry*; D002122:Calcium Chloride / Q000737:chemistry*; D002214:Capsules / Q000737:chemistry*; D003432:Cross-Linking Reagents / Q000737:chemistry*; D004577:Electron Probe Microanalysis; D020723:Glucuronic Acid / Q000737:chemistry; D006603:Hexuronic Acids / Q000737:chemistry; D011760:Pyrrolidinones / Q000737:chemistry*
D000179:Acrylates; D000464:Alginates; D002214:Capsules; D003432:Cross-Linking Reagents; D006603:Hexuronic Acids; D011760:Pyrrolidinones; C042670:N-vinyl-2-pyrrolidinone; D020723:Glucuronic Acid; C036658:acrylic acid; D002122:Calcium Chloride