Balance Sheets - USD ($)	Sep. 30, 2015	Dec. 31, 2014
Current assets:
Cash and cash equivalents	$ 39,404,313	$ 40,182,141
Prepaid expenses	1,260,699	803,775
Total current assets	40,665,012	40,985,916
Property and equipment, net of accumulated depreciation of $299,943 in 2015 and $285,643 in 2014	12,320,365	12,046,267
Prepaid expenses, long-term	1,751,051	1,677,434
Deferred financing costs, net	330,948	98,401
Other assets	18,208	18,208
Total assets	55,085,584	54,826,226
Current liabilities:
Accounts payable	4,349,935	2,631,217
Accrued expenses	2,348,157	1,062,113
Loan payable, current portion		5,003,143
Warrant liability	251,247	296,048
Total current liabilities	6,949,339	8,992,521
Loan payable, long-term	$ 15,390,295	$ 9,827,758
Commitments and contingencies
Stockholders' equity:
Common stock, $.0001 par value, authorized 150,000,000 shares; 22,292,167 shares issued and outstanding as of September 30, 2015 and 18,634,872 shares issued and outstanding as of December 31, 2014	$ 2,230	$ 1,864
Additional paid-in capital	193,571,822	170,395,934
Accumulated deficit	(160,828,102)	(134,391,851)
Total stockholders' equity	32,745,950	36,005,947
Total liabilities and stockholders' equity	$ 55,085,584	$ 54,826,226