Statements of Cash Flows - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Operating activities
Net loss	$ (12,229,512)	$ (10,748,531)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation expense	1,819,431	1,706,524
Non-cash interest		120,889
Financing costs allocated to warrant liability		533,692
Change in fair value of warrant liability	1,005,349	(597,615)
Change in operating assets and liabilities:
Prepaid expenses and other assets	24,662	554,014
Accounts payable and accrued expenses	663,165	(276,715)
Net cash used in operating activities	(8,716,905)	(8,707,742)
Financing activities
Payment on bank loan		(4,500,000)
Proceeds from issuance of common stock, net	7,389,101	354,855
Proceeds from issuance of common stock and warrants, net		13,168,803
Net cash provided by financing activities	7,389,101	9,023,658
Net increase (decrease) in cash and cash equivalents	(1,327,804)	315,916
Cash and cash equivalents at beginning of period	9,007,071	8,691,155
Cash and cash equivalents at end of period	7,679,267	9,007,071
Supplemental disclosure of cash flow information
Interest paid		169,813
Non-cash financing activities
Fair value of warrants issued to placement agent		$ 369,863
Reclassification of warrant liability to equity due to exercise of warrants	$ 1,399,091