Summary of significant accounting policies - Potentially dilutive securities (Details) - shares	6 Months Ended
	Jun. 30, 2025	Jun. 30, 2024
Potentially dilutive securities
Total shares of common stock equivalents	3,058,804	2,998,161
March 2024 Private Placement | Pre-funded Warrants
Potentially dilutive securities
Warrants to purchase of shares	507,076
Convertible preferred stock (as converted)
Potentially dilutive securities
Total shares of common stock equivalents	15,596	28,112
Employee Stock Option
Potentially dilutive securities
Total shares of common stock equivalents	815,723	734,131
Warrants to purchase common stock
Potentially dilutive securities
Total shares of common stock equivalents	2,194,788	2,194,788
Unvested restricted stock units
Potentially dilutive securities
Total shares of common stock equivalents	32,697	41,130