Note 10 - Stock-Based Compensation - Summary of Stock Option Compensation Expense (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Research and Development Expense [Member]
Stock-based compensation expense	$ 152,645	$ 32,825	$ 384,170	$ 32,825
General and Administrative Expense [Member]
Stock-based compensation expense	374,544	108,490	748,446	258,375
Stock-based compensation expense	$ 527,189	$ 141,315	$ 1,132,616	$ 291,200