Consolidated Balance Sheets (USD $)	Sep. 30, 2013	Dec. 31, 2012
Current assets:
Cash and cash equivalents	$ 18,333,540	$ 12,825,090
Restricted cash	601,441	601,351
Prepaid expenses	117,749	143,867
Total current assets	19,052,730	13,570,308
Property, equipment and leasehold improvements, net	2,430,834	2,311,942
Other assets	162,870	179,415
Total assets	21,646,434	16,061,665
Current liabilities:
Accounts payable	707,559	1,152,550
Note payable-current portion	112,774
Capital lease payable-current portion	11,119	32,606
Derivative warrant liability		14,584,818
Accrued expenses	1,263,115	1,021,275
Total current liabilities	2,094,567	16,791,249
Loan payable	1,920,000	1,578,000
Note payable-less current portion	36,994
Capital lease payable-less current portion		2,799
Total liabilities	4,051,561	18,372,048
Commitments and contingencies
Stockholders' equity (deficit):
Common stock, $0.00001 par value, authorized 200,000,000 shares at September 30, 2013 and December 31, 2012; issued and outstanding 78,729,618 and 65,881,122 shares at September 30, 2013 and December 31, 2012, respectively	787	659
Additional paid-in capital	93,796,109	40,842,339
Deficit accumulated during the development stage	(76,202,023)	(43,153,381)
Total stockholders' equity (deficit)	17,594,873	(2,310,383)
Total liabilities and stockholders' equity (deficit)	$ 21,646,434	$ 16,061,665