The challenge of exchanging oxygen, nutrients, and wastes typically limits the thickness of engineered tissues to a few hundred µm. Moreover there is a scarcity of research involving tissue culture under controlled oxygen conditions, a contributing factor to poor prediction of in vivo behavior. In an effort toward overcoming these limitations, we describe the development of a stable artificial oxygen carrier (AOC) for use in liquid and/or hydrogel phases of perfusion bioreactors and other culture systems. Stable emulsions were prepared by sonicating a novel, proprietary mixture of perfluorocarbon (PFC) and synthetic stabilizer in PBS for ten minutes on ice. O2 affinity was investigated by measuring the rate of decline of pO2 of 1 ml O2-saturated solutions exposed to ambient air. pO2 declined linearly, with 2% and 3% PFC emulsions exhibiting greatest oxygen affinity, retaining the dissolved gas in solution for over 7 hours, as compared to 6 hours for 3% perflubron emulsion or 2 hours for the PBS control. An oxygen saturation curve generated by mixing O2-saturated and depleted solutions for 2% PFC emulsion showed a linear increase in % saturation or O2 content with increasing pO2. Stability of emulsions was measured by dynamic light scattering. Cumulative droplet size was stable at 250-450 nm for 2% PFC over four weeks at 37º and 4º C and even following sonication. Polydispersity index remained below 0.35. Dense (1.7 g/ml) PFC droplets settled after several hours without coalescing and could be resuspended by agitation. Stability data is in accordance with highly similar materials characterized by Rapoport et al., which were also stable for days to weeks in vivo, as compared to minutes to hours for existing PFC emulsions. Along with stability, good oxygen affinity and unloading characteristics make these novel AOCs excellent candidates for use in liquid and/or gel phases of perfusion bioreactors, especially if combined with microfluidic channels. Such approaches may enable much tighter control over environmental O2 tension and a variety of studies of cell behavior in hypoxic and hyperoxic conditions. This material is based upon work supported under a National Science Foundation Graduate Research Fellowship. Development of perfluorocarbon emulsions was supported by the NIH (R01 EB1033 to N. Rapoport).