title: Fluorescent microparticles for sensing cell microenvironment oxygen levels within 3D scaffolds.
abstract: We present the development and characterization of fluorescent oxygen-sensing microparticles designed for measuring oxygen concentration in microenvironments existing within standard cell culture and transparent three-dimensional (3D) cell scaffolds. The microparticle synthesis employs poly(dimethylsiloxane) to encapsulate silica gel particles bound with an oxygen-sensitive luminophore as well as a reference or normalization fluorophore that is insensitive to oxygen. We developed a rapid, automated and non-invasive sensor analysis method based on fluorescence microscopy to measure oxygen concentration in a hydrogel scaffold. We demonstrate that the microparticles are non-cytotoxic and that their response is comparable to that of a traditional dissolved oxygen meter. Microparticle size (5-40 microm) was selected for microscale-mapping of oxygen concentration to allow measurements local to individual cells. Two methods of calibration were evaluated and revealed that the sensor system enables characterization of a range of hypoxic to hyperoxic conditions relevant to cell and tissue biology (i.e., pO(2) 10-160 mmHg). The calibration analysis also revealed that the microparticles have a high fraction of quenched luminophore (0.90+/-0.02), indicating that the reported approach provides significant advantages for sensor performance. This study thus reports a versatile oxygen-sensing technology that enables future correlations of local oxygen concentration with individual cell response in cultured engineered tissues.
authors.affiliation: Department of Chemical and Biochemical Engineering, University of Maryland, Baltimore County, 1000 Hilltop Circle, ECS 314, Baltimore, MD 21250, USA.
authors.forename: Miguel A
authors.initials: MA
authors.lastname: Acosta
authors.forename: Patrick
authors.initials: P
authors.lastname: Ymele-Leki
authors.forename: Yordan V
authors.initials: YV
authors.lastname: Kostov
authors.forename: Jennie B
authors.initials: JB
authors.lastname: Leach
mesh_terms: D001672:Biocompatible Materials / Q000737:chemistry; D015374:Biosensing Techniques / Q000295:instrumentation* / Q000379:methods; D002138:Calibration; D018929:Cell Culture Techniques / Q000295:instrumentation*; D002478:Cells, Cultured; D004129:Dimethylpolysiloxanes / Q000737:chemistry; D005456:Fluorescent Dyes / Q000378:metabolism; D008856:Microscopy, Fluorescence; D008863:Microspheres; D010100:Oxygen / Q000032:analysis* / Q000378:metabolism; D010316:Particle Size; D023822:Tissue Engineering; D054457:Tissue Scaffolds
chemical_list: D001672:Biocompatible Materials; D004129:Dimethylpolysiloxanes; D005456:Fluorescent Dyes; C013830:baysilon; D010100:Oxygen