Goodwill and other intangible assets (Details) - USD ($)		3 Months Ended		12 Months Ended
	Apr. 18, 2022	Sep. 30, 2022	Dec. 31, 2021	Dec. 31, 2022	Dec. 31, 2017	Mar. 31, 2023
Goodwill and other intangible assets
Balance of finite-lived intangible assets				$ 8,669,375		$ 8,305,625
Pelican Therapeutics, Inc.
Goodwill and other intangible assets
Goodwill acquired					$ 2,200,000
In-process research and development impairment		$ 3,500,000
Goodwill impairment loss			$ 1,500,000
Pelican Therapeutics, Inc. | In-process R&D.
Goodwill and other intangible assets
Finite-lived intangible assets acquired					$ 5,900,000
Carrying value written down			5,900,000
Intangible assets fair value			3,500,000
In-process research and development impairment			$ 2,400,000
Elusys Therapeutics
Goodwill and other intangible assets
Goodwill acquired	$ 3,300,000
Finite-lived intangible assets acquired	$ 9,700,000
In-process research and development impairment				$ 0
Remaining amortization period	80 months