Randal Kirk

A day after striking the latest in a series of its special "channel" collaborations, Intrexon has reloaded its bank account with a fresh $150 million infusion of cash, with significant added contributions from billionaire founder R.J. Kirk and his venture fund, Third Security.

Biotech billionaire RJ Kirk has hitched another therapeutic developer to his synthetic biology wagon at Intrexon. This time it's Fibrocell Science, an Exton, PA-based developer with a personalized cell therapy for "aesthetic dermatology" on the market.

Biotech startup Intrexon has expanded the synthetic biology shop's ties with drug developer Synthetic Biologics, picking up ownership in the partner as part of a deal focused on generating monoclonal antibodies for infectious diseases.

These days, it's good to have your own money to bank on when you're growing a biotech company. It's also extraordinarily rare. The following 15 venture round qualified as the top investments of the first half, as tracked by Thomson Reuters and the National Venture Capital Association.