Balance Sheets (Current Period Unaudited) (USD $)	Mar. 31, 2013	Dec. 31, 2012
Current assets:
Cash and cash equivalents	$ 20,366,679	$ 14,991,488
Investment securities – available for sale, at fair value	25,202,875	8,037,620
Accrued interest receivable on investment securities	283,082	65,925
Advances and deposits for investigator grants	131,706	246,252
Other current assets	430,451	307,699
Total current assets	46,414,793	23,648,984
Property and equipment (at cost, less accumulated depreciation of $999,961 and $924,961, respectively)	1,039,621	1,114,621
Other assets:
Deposits, deferred fees and other assets	477,293	567,188
Patent licensing fees, net	26,250	28,125
Total other assets	503,543	595,313
Total assets	47,957,957	25,358,918
Current liabilities:
Accounts payable	4,180,805	2,339,768
Accrued liabilities	1,097,445	1,254,979
Notes payable - current portion	1,883,752	1,410,455
Deferred revenue - current portion	500,000
Total current liabilities	7,662,002	5,005,202
Common stock warrant liability	3,635	4,283,932
Notes payable – non-current portion	3,173,389	3,661,147
Deferred revenue - non-current portion	4,375,000
Other non-current liabilities	442,950	446,779
Total liabilities	15,656,976	13,397,060
Stockholders' equity:
Preferred stock, $0.01 par value: 100,000 shares authorized and 20,000 and 5,000 shares issued at March 31, 2013 and December 31, 2012 and 5,037 and -0- shares outstanding at March 31, 2013 and December 31, 2012, respectively	50
Common stock, $0.01 par value; 75,000,000 shares authorized and 51,497,856 and 37,967,708 shares issued at March 31, 2013 and December 31, 2012 and 50,835,477 and 37,302,785 shares outstanding at March 31, 2013 and December 31, 2012, respectively	514,979	379,677
Additional paid-in capital	190,743,338	165,276,069
Accumulated other comprehensive loss	(158,556)	(126,607)
Accumulated deficit	(156,118,622)	(150,876,770)
Subtotal	34,981,189	14,652,369
Treasury stock, at cost (662,379 and 664,921 shares at March 31, 2013 and December 31, 2012, respectively)	(2,680,208)	(2,690,511)
Total stockholders' equity	32,300,981	11,961,858
Total liabilities and stockholders' equity	$ 47,957,957	$ 25,358,918