title: Oxygen sensitivity and biocompatibility of an implantable paramagnetic probe for repeated measurements of tissue oxygenation.
abstract: The use of oxygen-sensing water-insoluble paramagnetic probes, such as lithium octa-n-butoxynaphthalocyanine (LiNc-BuO), enables repeated measurements of pO(2) from the same location in tissue by electron paramagnetic resonance (EPR) spectroscopy. In order to facilitate direct in vivo application, and hence eventual clinical applicability, of LiNc-BuO, we encapsulated LiNc-BuO microcrystals in polydimethylsiloxane (PDMS), an oxygen-permeable and bioinert polymer, and developed an implantable chip. In vitro evaluation of the chip, performed under conditions of sterilization, high-energy irradiation, and exposure to cultured cells, revealed that it is biostable and biocompatible. Implantation of the chip in the gastrocnemius muscle tissue of mice showed that it is capable of repeated and real-time measurements of tissue oxygenation for an extended period. Functional evaluation using a murine tumor model established the suitability and applicability of the chip for monitoring tumor oxygenation. This study establishes PDMS-encapsulated LiNc-BuO as a promising choice of probe for clinical EPR oximetry.
authors.affiliation: Department of Internal Medicine, Ohio State University, 420 West 12th Avenue, Room 114, Columbus, OH 43210, USA.
authors.forename: Guruguhan
authors.initials: G
authors.lastname: Meenakshisundaram
authors.forename: Edward
authors.initials: E
authors.lastname: Eteshola
authors.forename: Ramasamy P
authors.initials: RP
authors.lastname: Pandian
authors.forename: Anna
authors.initials: A
authors.lastname: Bratasz
authors.forename: Karuppaiyah
authors.initials: K
authors.lastname: Selvendiran
authors.forename: Stephen C
authors.initials: SC
authors.lastname: Lee
authors.forename: Murali C
authors.initials: MC
authors.lastname: Krishna
authors.forename: Harold M
authors.initials: HM
authors.lastname: Swartz
authors.forename: Periannan
authors.initials: P
authors.lastname: Kuppusamy