| Schedule of Segment Reporting Information, by Segment [Table Text Block] |   | Three Months Ended March 31, 2021 |  |  |  |  |  |  |  |  |  |  |  |  |   | License revenue |  | $ | 22,486 |  |  | $ | — |  |  | $ | — |  |  | $ | 22,486 |  |   | Grant and other revenue |  |  | 101,251 |  |  |  | — |  |  |  | — |  |  |  | 101,251 |  |   | Total revenue |  |  | 123,737 |  |  |  | — |  |  |  | — |  |  |  | 123,737 |  |   | Cost of revenue |  |  | — |  |  |  | — |  |  |  | — |  |  |  | — |  |   | Research and development expenses |  |  | 1,094,390 |  |  |  | 128,364 |  |  |  | — |  |  |  | 1,222,754 |  |   | Selling, general and administrative expenses, excluding depreciation and amortization  (1) |  |  | — |  |  |  | 2,006 |  |  |  | 2,210,991 |  |  |  | 2,212,997 |  |   | Depreciation and amortization  (2) |  |  | 6,040 |  |  |  | — |  |  |  | 11,708 |  |  |  | 17,748 |  |   |  |  |  | (976,693 | ) |  |  | (130,370 | ) |  |  | (2,222,699 | ) |  |  | (3,329,762 | ) |   |  |  |  | — |  |  |  | — |  |  |  | 362,870 |  |  |  | 362,870 |  |   | Net loss |  |  | (976,693 | ) |  |  | (130,370 | ) |  |  | (1,859,829 | ) |  |  | (2,966,892 | ) |   | Total assets, net of depreciation and amortization: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |   | United States |  | $ | 160,669 |  |  | $ | — |  |  | $ | 9,723,212 |  |  | $ | 9,883,881 |  |   | International |  |  | 193,194 |  |  |  | — |  |  |  | — |  |  |  | 193,194 |  |   | Capital expenditures |  |  | — |  |  |  | — |  |  |  | — |  |  |  | — |  |   | Three Months Ended March 31, 2020 |  |  |  |  |  |  |  |  |  |  |  |  |   | Royalty revenue |  | $ | 15,221 |  |  | $ | — |  |  | $ | — |  |  | $ | 15,221 |  |   | Grant and other revenue |  |  | 58,916 |  |  |  | 82,135 |  |  |  | — |  |  |  | 141,051 |  |   | Total revenue |  |  | 74,137 |  |  |  | 82,135 |  |  |  | — |  |  |  | 156,272 |  |   | Cost of revenue |  |  | 609 |  |  |  | — |  |  |  | — |  |  |  | 609 |  |   | Research and development expenses |  |  | 957,626 |  |  |  | 41,643 |  |  |  | — |  |  |  | 999,269 |  |   | Selling, general and administrative expenses, excluding depreciation and amortization  (1) |  |  | — |  |  |  | (1,522 | ) |  |  | 1,812,433 |  |  |  | 1,810,911 |  |   | Depreciation and amortization  (2) |  |  | — |  |  |  | — |  |  |  | 16,843 |  |  |  | 16,843 |  |   | (Loss) income from operations  (3) |  |  | (884,098 | ) |  |  | 42,014 |  |  |  | (1,829,276 | ) |  |  | (2,671,360 | ) |   |  |  |  | — |  |  |  | — |  |  |  | (2,248 | ) |  |  | (2,248 | ) |   | Net loss |  |  | (884,098 | ) |  |  | 42,014 |  |  |  | (1,831,524 | ) |  |  | (2,673,608 | ) |   | Total assets, net of depreciation and amortization: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |   | United States |  | $ | 36,671 |  |  | $ | 2,494 |  |  | $ | 4,438,066 |  |  | $ | 4,477,231 |  |   | International |  |  | — |  |  |  | — |  |  |  | — |  |  |  | — |  |   | Capital expenditures |  |  | — |  |  |  | — |  |  |  | 6,459 |  |  |  | 6,459 |  |  |