Consolidated Balance Sheets (USD $)	Dec. 31, 2012	Dec. 31, 2011
Current assets:
Cash and cash equivalents	$ 12,825,090	$ 4,363,712
Restricted cash	601,351	547,883
Prepaid expenses and other current assets	143,867	104,022
Total current assets	13,570,308	5,015,617
Property and equipment, net	2,311,942	520,482
Other assets	179,415	166,139
Total assets	16,061,665	5,702,238
Current liabilities:
Accounts payable	1,152,550	567,195
Loan payable-current portion		50,578
Capital lease payable-current portion	32,606	30,724
Derivative warrant liability	14,584,818	35,473,230
Accrued expenses	1,021,275	618,369
Total current liabilities	16,791,249	36,740,096
Loan payable-less current portion	1,578,000	83,794
Capital lease payable-less current portion	2,799	38,042
Total liabilities	18,372,048	36,861,932
Commitments and contingencies
Stockholders' deficit:
Common stock, $0.00001 par value, authorized 200,000,000 shares; issued and outstanding 65,881,122 and 53,760,471 shares at December 31, 2012 and 2011 respectively	659	538
Additional paid-in capital	40,842,339	16,656,830
Deficit accumulated during the development stage	(43,153,381)	(47,817,062)
Total stockholders' deficit	(2,310,383)	(31,159,694)
Total liabilities and stockholders' deficit	$ 16,061,665	$ 5,702,238