Private equity firm The Carlyle Group has agreed to purchase a blood-testing unit from health care giant Johnson & Johnson in a deal worth $4.15 billion.

Carlyle is financing the acquisition of the Raritan, N.J.-based unit, called Ortho-Clinical Diagnostics, —which the buyer expects to close “in the middle of 2014,” pending regulatory approval—with a mixture of debt and cash from its sixth buyout fund, which is funded in the amount of roughly $13 billion.