Note 10 - Stock-based Compensation (10-Q) (Tables)

3 Months Ended

12 Months Ended

Mar. 31, 2024

Dec. 31, 2023

Notes Tables

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

	Three Months Ended March 31,
	2024		2023
Research and development	$	63,797	$	40,126
General and administrative		154,418		31,114
Total stock-based compensation expense	$	218,215	$	71,240

	Year Ended December 31,
	2023		2022
Research and development	$	143,685	$	174,710
General and administrative		263,947		159,125
Total stock-based compensation expense	$	407,632	$	333,835

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

	Number of Options			Weighted average exercise price per share		Weighted average remaining contractual life (in years)		Aggregate intrinsic value
Balance at January 1, 2024		349,374		$	51.15
Granted		169,934			9.52
Expired		(51	)		28,897.06
Outstanding at March 31, 2024		519,257		$	34.69		8.5		—
Exercisable at March 31, 2024		192,004		$	79.03		6.7		—

	Number of Options			Weighted average exercise price per share		Weighted Average Remaining Contractual Term		Aggregate Intrinsic Value
Balance at January 1, 2023		114,516		$	25.98		6.72
Options assumed in the merger		52,574		$	313.67
Granted		198,600		$	5.95
Cancelled		(15,957	)	$	180.80
Exercised		(359	)	$	5.33
Outstanding at December 31, 2023		349,374		$	51.15		8.12	$	358,340
Exercisable at December 31, 2023		157,301		$	103.67		6.35	$	39,820

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

	Three Months Ended March 31,
	2024
Expected term (in years)		5.74 - 5.76
Risk-free interest rate		4.06 - 4.14	%
Expected volatility		79.13 - 79.31	%
Dividend yield		—

	December 31,
	2023			2022
Expected term (in years)	5.75				6.00
Risk-free interest rate	3.9%	-	4.5%		1.9	%
Expected volatility	81.7%	-	83.3%		80.3	%
Dividend yield	0.0%				0.0	%