Note 7 - Stockholder's Equity (Tables)
|
12 Months Ended |
Dec. 31, 2025 |
| Notes Tables |
|
| Share-Based Payment Arrangement, Cost by Plan [Table Text Block] |
| | | For the year ended December 31, | |
| | | 2025 | | | 2024 | |
| Research and development | | $ | 124 | | | $ | 269 | |
| General and administrative | | | 541 | | | | 967 | |
| Total stock-based compensation expense | | $ | 665 | | | $ | 1,236 | |
|
| Schedule of Unvested Restricted Stock Units Roll Forward [Table Text Block] |
| | | Number of Units and Awards | | | Weighted Average Grant Date Fair Value | |
| Unvested balance at December 31, 2023 | | | 1,311 | | | $ | 197.19 | |
| Granted | | | 235,000 | | | | 2.46 | |
| Vested | | | (283 | ) | | | 85.50 | |
| Unvested balance at December 31, 2024 | | | 236,028 | | | $ | 3.44 | |
| Forfeited | | | (212 | ) | | | 171.94 | |
| Vested | | | (416 | ) | | | 85.50 | |
| Unvested balance at December 31, 2025 | | | 235,400 | | | $ | 3.19 | |
|
| Share-Based Payment Arrangement, Option, Activity [Table Text Block] |
| | | Stock Options | | | Weighted Average Exercise Price | | | Weighted Average Remaining Contractual Term (in years) | | | Aggregate Intrinsic Value (in thousands) | |
| Outstanding as of December 31, 2023 | | | 22,474 | | | $ | 85.5000 | | | | 9.50 | | | $ | — | |
| Granted | | | 234,000 | | | | 2.46 | | | | 10.00 | | | $ | — | |
| Outstanding as of December 31, 2024 | | | 256,474 | | | $ | 9.74 | | | | 9.62 | | | $ | — | |
| Outstanding as of December 31, 2025 | | | 256,474 | | | $ | 9.74 | | | | 8.62 | | | $ | — | |
| Expected to vest | | | 162,624 | | | $ | 5.84 | | | | 8.68 | | | $ | — | |
| Vested and Exercisable as of December 31, 2025 | | | 93,850 | | | | 16.48 | | | | 8.52 | | | $ | — | |
|
| Schedule of Share-Based Payment Award, Stock Options, Valuation Assumptions [Table Text Block] |
| | | For the Year Ended December 31, | |
| | | 2024 | |
| Risk-free interest rate | | | 3.6 | % |
| Expected dividend yield | | | — | |
| Expected term in years | | | 5.6 | |
| Expected volatility | | | 135.0 | % |
|
| Schedule of Stockholders' Equity Note, Warrants or Rights [Table Text Block] |
| | | Warrants | | | Weighted Average Exercise Price | | | Aggregate Intrinsic Value (in thousands) | |
| Outstanding, December 31, 2023 | | | 524,601 | | | $ | 32.42 | | | $ | 1 | |
| Granted | | | 1,861,817 | | | $ | 6.23 | | | | — | |
| Exercised | | | (910,218 | ) | | $ | 10.16 | | | | — | |
| Outstanding, December 31, 2024 | | | 1,476,200 | | | $ | 8.64 | | | $ | — | |
| Expired | | | (703,459 | ) | | $ | 6.52 | | | | — | |
| Outstanding, December 31, 2025 | | | 772,741 | | | $ | 10.56 | | | $ | — | |
|
| Fair Value Measurement Inputs and Valuation Techniques [Table Text Block] |
| | | December 31, | | | December 31, | |
| | | 2025 | | | 2024 | |
| Stock price | | $ | 0.68 | | | $ | 2.00 | |
| Risk-free interest rate | | | 3.75 | % | | | 4.27 | % |
| Expected dividend yield | | | — | | | | — | |
| Expected term in years | | | 1.78 | | | | 2.80 | |
| Expected volatility | | | 151 | % | | | 155 | % |
|
| Warrant [Member] |
|
| Notes Tables |
|
| Fair Value Measurement Inputs and Valuation Techniques [Table Text Block] |
| | | January 2023 | | | New Series A | | | New Series B | |
| | | Warrants | | | Warrants | | | Warrants | |
| Stock price | | $ | 14.25 | | | $ | 14.25 | | | $ | 14.25 | |
| Risk-free interest rate | | | 4.40 | % | | | 4.02 | % | | | 4.40 | % |
| Expected dividend yield | | | — | | | | — | | | | — | |
| Expected term in years | | | 2.1 | | | | 5.0 | | | | 1.5 | |
| Expected volatility | | | 185 | % | | | 138 | % | | | 187 | % |
| | | October 2022 | | | November 2023 | | | January 2024 | | | Series C | | | Series D | | | Placement Agent | |
| | | Warrants | | | Warrants | | | Warrants | | | Warrants | | | Warrants | | | Warrants | |
| Stock price | | $ | 4.76 | | | $ | 4.76 | | | $ | 4.76 | | | $ | 4.76 | | | $ | 4.76 | | | $ | 4.76 | |
| Risk-free interest rate | | | 4.79 | % | | | 4.64 | % | | | 4.64 | % | | | 4.64 | % | | | 4.96 | % | | | 4.64 | % |
| Expected dividend yield | | | — | | | | — | | | | — | | | | — | | | | — | | | | — | |
| Expected term in years | | | 3.4 | | | | 4.5 | | | | 4.7 | | | | 5.0 | | | | 1.5 | | | | 5.0 | |
| Expected volatility | | | 160 | % | | | 148 | % | | | 145 | % | | | 141 | % | | | 132 | % | | | 141 | % |
|