PROJECT SUMMARY Chemeleon is developing an easy-to-use colorimetric biosensor (like a pH test strip) to aid doctors in eliminating uncertainty and delays in diagnosing cerebrospinal fluid (CSF) leakage. The product has applications in multiple clinical scenarios, including traumatic brain injuries (TBI) in emergency departments (ED), lumbar punctures, spontaneous CSF leak cases, and during spinal surgeries. CSF leaks develop when there is a rupture in the membranes surrounding the brain or spinal cord. While some CSF leaks occur spontaneously, most are a result of a TBI, presenting as rhinorrhea, or a result of spinal surgery in which the clear CSF fluid mixes with blood and other liquids. Diagnosing CSF leaks is a well-known problem for neurosurgeons, as it is difficult to differentiate from common fluids. Currently, patient samples are sent out for third-party analysis, taking several days for results to return. Delayed treatment during this time increases patient morbidity, as well as further complications such as meningitis, brain infections, or stroke. In the case of spinal surgeries, a dural tear resulting in a CSF leak is a risk of spinal procedures. Currently there is no accurate, on-site test to help neurosurgeons identify CSF leaks during surgery. The innovation of the proposed approach lies in the integration of a synthetic nanoreceptor, able to capture the ?2-transferrin protein uniquely found in CSF, with a nanostructured surface capable of generating visible color changes upon capture of the targeted protein. This product will give neurosurgeons a simple to use real-time diagnostics tool for identifying a CSF leaks. This technology will significantly reduce the number of undiagnosed and misdiagnosed CSF leaks, improving overall patient outcomes by preventing delayed treatment and the complications that arise from it.. Our Phase I hypothesis is that a designed nanostructured surface can be functionalized to selectively bind the ?2-transferrin protein unique to CSF, inducing a measurable color change in the visible wavelength range. Our first specific aim is to achieve highly specific nanoreceptors for ?2-transferrin protein binding using synthetic polymers. Our second aim is to achieve a color shift after ?2-transferrin protein binding, by integrating nanoreceptor with structural color reporter elements. In Phase II, we plan to develop a larger 4x2 test strip, coated with the sensor platform, that can produce a more significant spectra shift upon ?2-transferrin protein binding, which will be visible by eye under ambient lighting conditions. It is estimated that there are 235,000 hospitalizations yearly for TBI and over 1.4 million spinal surgeries per year. In each case, physicians could benefit greatly by utilizing our technology to confirm or rule out CSF leaks. With potential customers in every hospital in the US, we will first target key neurosurgeons to utilize our sensors in treating TBI and spinal surgeries, focusing on developing relationships in mid-Atlantic US medical markets. In parallel, we will develop relationships with medical device distribution networks to expand the footprint towards a national market.