Biotech firms’ reach into the Boston suburbs continues as Optimum Asset Management announced the sale of an 85K SF facility at 220 Mill Road in Chelmsford to life sciences giant Thermo Fisher Scientific.

An Optimum spokesman declined to disclose the price, but public records show Thermo Fisher subsidiary Life Technologies Corp. paid $11.7M for 220 Mill Road in September.

City records show Optimum purchased the building, roughly 28 miles from Kendall Square in Cambridge, in August 2019 for nearly $5M. Optimum said it spent an undisclosed amount of capital to renovate the building and draw Thermo Fisher, including adding a high bay.

The site includes office and research and development space outside of Boston, where lab space was already scarce before the coronavirus pandemic. Thermo Fisher, headquartered in Waltham, provides equipment and services to the life sciences industry and is advertising a service on its website that allows companies to scale up their COVID-19 testing.

Optimum founder and Managing Partner Alberto Matta lauded the internal rate of return of more than 40% after a one year holding period on 220 Mill Road on the investment for the Optimum Real Estate Fund - USA II.

"We are pleased to build on our strong track record of investor returns with the IRR achieved on this timely exit," Matta said in a statement. "The transaction is particularly noteworthy in the coronavirus environment, which continues to impact office space more broadly."

Representatives for the firms in the deal didn't respond to inquiries.

Optimum said it partnered with Spaulding & Slye Investments, the investment firm that remained as a subsidiary when JLL acquired the Spaulding & Slye brokerage in 2006, in the sale.