Statements of Cash Flows - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Operating activities
Net loss	$ (7,566,080)	$ (12,229,512)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation expense	1,539,469	1,819,431
Change in fair value of warrant liability	(433,392)	1,005,349
Change in operating assets and liabilities:
Prepaid expenses and other assets	(78,172)	24,662
Accounts payable and accrued expenses	(440,385)	663,165
Net cash used in operating activities	(6,978,560)	(8,716,905)
Financing activities
Proceeds from issuance of common stock, net	4,618,297	7,389,101
Net cash provided by financing activities	4,618,297	7,389,101
Net decrease in cash and cash equivalents	(2,360,263)	(1,327,804)
Cash and cash equivalents at beginning of period	7,679,267	9,007,071
Cash and cash equivalents at end of period	5,319,004	7,679,267
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