This Small Business Innovation Research (SBIR) Phase I project is the development of a lung tissue model based on a new cell culturing platform utilizing nanoparticle-based reagents and magnetic fields to levitate tissue samples and allow three-dimensional (3D) growth. This method naturally grows tissue at the air-liquid interface and is well suited for co-culturing, which are crucial for an accurate in vitro lung model. The application and market for this product will be drug discovery and toxicity screening. In the early stages of drug development, candidate compounds are screened for efficacy and toxicity in in vitro model systems. Currently, these tests are performed in high-throughput assays using two-dimensional (2D) tissue, but 2D culturing alters cellular responses and often leads to misleading results. Subsequent tests in animal models are costly, ethically contentious, and sometimes inaccurate since model organisms may not faithfully reproduce human responses.<br/><br/>The broader impact of this proposal follows from the potential to use the tissue model for improved in vitro efficacy and toxicity assays to reduce the cost of drug development. The reduction of animal testing is also an important goal for ethical reasons. In addition, a lung tissue model that recapitulates natural tissue properties and responses can also find application in toxicity screening of environmental, cosmetic, and industrial factors. The current worldwide expenditure for animal toxicity testing is over $10 billion/yr, and replacement in vitro methods are already over $200 million/yr and growing rapidly. An improved lung model will have significant impact in these areas.