title: A paramagnetic implant containing lithium naphthalocyanine microcrystals for high-resolution biological oximetry.
abstract: Lithium naphthalocyanine (LiNc) is a microcrystalline EPR oximetry probe with high sensitivity to oxygen [R.P. Pandian, M. Dolgos, C. Marginean, P.M. Woodward, P.C. Hammel, P.T. Manoharan, P. Kuppusamy, Molecular packing and magnetic properties of lithium naphthalocyanine crystal: hollow channels enabling permeability and paramagnetic sensitivity to molecular oxygen J. Mater. Chem. 19 (2009) 4138-4147]. However, direct implantation of the crystals in the tissue for in vivo oxygen measurements may be hindered by concerns associated with their direct contact with the tissue/cells and loss of EPR signal due to particle migration in the tissue. In order to address these concerns, we have developed encapsulations (chips) of LiNc microcrystals in polydimethyl siloxane (PDMS), an oxygen-permeable, bioinert polymer. Oximetry evaluation of the fabricated chips revealed that the oxygen sensitivity of the crystals was unaffected by encapsulation in PDMS. Chips were stable against sterilization procedures or treatment with common biological oxidoreductants. In vivo oxygen measurements established the ability of the chips to provide reliable and repeated measurements of tissue oxygenation. This study establishes PDMS-encapsulated LiNc as a potential probe for long-term and repeated measurements of tissue oxygenation.
authors.affiliation: Department of Internal Medicine, Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH 43210, USA.
authors.forename: Guruguhan
authors.initials: G
authors.lastname: Meenakshisundaram
authors.forename: Ramasamy P
authors.initials: RP
authors.lastname: Pandian
authors.forename: Edward
authors.initials: E
authors.lastname: Eteshola
authors.forename: Stephen C
authors.initials: SC
authors.lastname: Lee
authors.forename: Periannan
authors.initials: P
authors.lastname: Kuppusamy
mesh_terms: D000818:Animals; D001672:Biocompatible Materials; D002138:Calibration; D003460:Crystallization; D004129:Dimethylpolysiloxanes; D004339:Drug Compounding; D004567:Electrodes, Implanted; D004578:Electron Spin Resonance Spectroscopy / Q000295:instrumentation*; D005260:Female; D051379:Mice; D008809:Mice, Inbred C3H; D008838:Microcomputers; D018482:Muscle, Skeletal / Q000737:chemistry / Q000378:metabolism; D010084:Oxidation-Reduction; D010092:Oximetry / Q000295:instrumentation*; D011166:Porphyrins / Q000737:chemistry*; D013242:Sterilization
chemical_list: D001672:Biocompatible Materials; D004129:Dimethylpolysiloxanes; D011166:Porphyrins; C487013:lithium octa-n-butoxynaphthalocyanine; C013830:baysilon