Condensed Statements of Cash Flows (Unaudited) - USD ($)	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Operating activities
Net loss	$ (4,285,980)	$ (6,678,008)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation expense	781,204	929,029
Change in fair value of warrant liability	(433,392)	1,810,835
Change in operating assets and liabilities:
Prepaid expenses and other assets	167,364	(312,224)
Accounts payable and accrued expenses	(808,904)	467,338
Net cash used in operating activities	(4,579,708)	(3,783,030)
Financing activities
Proceeds from issuance of common stock, net	3,431,520	7,332,239
Net cash provided by financing activities	3,431,520	7,332,239
Net increase (decrease) in cash and cash equivalents	(1,148,188)	3,549,209
Cash and cash equivalents at beginning of period	7,679,267	9,007,071
Cash and cash equivalents at end of period	6,531,079	12,556,280
Non-cash financing activities
Reclassification of warrant liability to equity due to exercise of warrants		$ 1,399,091
Reclassification of warrant liability to equity due to amendment of warrants	$ 3,267,885