C2N Diagnostics, a St. Louis-based biotechnology firm that has created a blood test designed to help doctors detect Alzheimer’s disease, made headlines in the past year when it raised $15 million in funding to enhance its technology. The capital was earmarked for development of PrecivityAD2, a second version of its blood test. It has also expanded its leadership team and publicly shared research results it says “demonstrate the accuracy” of its blood tests.