Avantra Biosciences, a Woburn, MA-based developer of protein biomarker technology to detect a range of diseases, has raised $7 million in a Series A funding round, according to an SEC filing. The investors included Courtagen Capital Group of Charlestown, MA, as well as unnamed institutional and individual backers, said R. Brian McKernan, the chief executive of Avantra. Avantra, founded in 2009, is developing the former assets of Decision Biomarkers, said McKernan, who is also a managing partner of Courtagen Capital. His group purchased the technology of the former Waltham, MA-based Decision Biomarkers late last year after the latter firm filed for bankruptcy, he said. McKernan previously served as CEO of Agencourt Bioscience, the Massachusetts provider of DNA and RNA research tools and services that was sold to the Brea, CA-based scientific instruments maker Beckman Coulter (NYSE:BEC) in 2005 for more than $140 million.