Note 11 - Stock Option Plans (Tables)

3 Months Ended

Mar. 31, 2023

Notes Tables

Share-Based Payment Arrangement, Option, Activity [Table Text Block]

	Options			Weighted Average Exercise Price		Weighted Average Remaining Contractual Life (years)		Aggregate Intrinsic Value
Outstanding options, December 31, 2022		7,095,462		$	1.99		5.79	$	109,891
Granted		2,546,750		$	0.54
Forfeited		(13,963	)	$	1.59
Exercised		(3,500	)	$	0.54
Expired		(28,086	)	$	5.21
Outstanding options, March 31, 2023		9,596,663		$	1.59		6.72	$	—
Options vested and exercisable, March 31, 2023		4,451,753		$	1.92		3.39	$	—

Schedule of Share-Based Payment Award, Stock Options, Valuation Assumptions [Table Text Block]

	Three Months Ended March 31,
	2023			2022
Expected volatility		81.9	%		78.0 - 80.8	%
Weighted-average volatility		81.9	%		79.0	%
Expected dividends		—			—
Expected term (in years)		6.08			5.50 - 6.08
Risk-free rate		3.76	%		1.38 - 2.41	%

Nonvested Restricted Stock Shares Activity [Table Text Block]

	Number of shares		Weighted Average Grant Date Fair Value
Unvested as of December 31, 2022		350,000	$	1.72
Granted		318,875	$	0.54
Unvested as of March 31, 2023		668,875	$	1.16

Share-Based Payment Arrangement, Expensed and Capitalized, Amount [Table Text Block]

	Three Months Ended March 31,
	2023		2022
Research and development	$	147,691	$	368,225
General and administrative		455,089		529,375
Total	$	602,780	$	897,600