The deal was backed by Noble Fund Managers with debt supplied by HSBC.

Dr Tony Flinn, Onyx’s co-founder and chief executive, led the buy-out team, supported by research and development director Dr Derek Londesbrough, commercial director Denise Bowser and head of finance Nathan Lane.

Noble’s investment was managed by Charles McMicking and Doug Lawson of its private equity team, and Dr Louis Nisbet of its healthcare division.

Nisbet, who joins Onyx as a director, comments: ‘This investment adds to our growing healthcare portfolio and I look forward to working with the management team to achieve our goals.’

This is Noble’s latest investment in the healthcare industry after the firm provided development capital to Optasia Medical in November.

Sunderland-based Onyx was founded in 2000 and provides services including research and custom synthesis. It also supplies proprietary technology-based chemicals.