Stock Option Plans and Warrants to Purchase Common Stock (Tables)

12 Months Ended

Dec. 31, 2015

Equity Incentive Plan [Member]

Share-based Compensation Arrangement by Share-based Payment Award

Summary of option and warrant activity

	December 31,
	2015			2014
Shares available for grant at plan approval		3,000,000			-
Options granted		(477,000	)		-
Shares available for grant at end of year		2,523,000			-

Share Based Compensation [Member]

Share-based Compensation Arrangement by Share-based Payment Award

Summary of option and warrant activity

Share-based Compensation	2015		2014
Research and Development	$	260,204	$	308,847
General and Administrative		394,277		411,303
Total	$	654,481	$	720,150

Stock options [Member]

Share-based Compensation Arrangement by Share-based Payment Award

Summary of option and warrant activity

	Options			Weighted Average Options Exercise Price
Balance at December 31, 2013		2,051,511		$	2.63
Granted		637,495			1.79
Exercised		(36,672	)		0.77
Forfeited		(164,055	)		3.13
Balance at December 31, 2014		2,488,279		$	2.40
Granted		605,340			1.19
Exercised		(33,125	)		0.58
Forfeited		(291,882	)		3.13
Balance at December 31, 2015		2,768,612		$	2.13

Weighted-average range of exercise prices for options and warrants outstanding and exercisable

Price Range	Weighted Average Remaining Contractual Life in Years		Outstanding Options		Exercisable Options
$0.30-$2.20		8.03		2,170,838		1,484,425
$2.26-$4.10		5.36		174,774		174,774
$4.64-$9.40		3.22		423,000		423,000
Total		7.28		2,768,612		2,082,199

Warrant [Member]

Share-based Compensation Arrangement by Share-based Payment Award

Summary of option and warrant activity

	Warrants			Weighted Average Warrant Exercise Price
Balance at December 31, 2013		8,156,526		$	2.17
Granted		1,169,318			1.48
Exercised		(586,081	)		1.65
Expired		(1,470,263	)		3.49
Balance at December 31, 2014		7,269,500		$	1.15
Exercised		(1,746,429	)		0.64
Expired		(596,952	)		5.59
Balance at December 31, 2015		4,926,119		$	0.74

Weighted-average range of exercise prices for options and warrants outstanding and exercisable

Price  Range	Weighted Average Remaining Contractual Life in Years		Outstanding Warrants		Exercisable Warrants
$.51-$0.53		2.4		3,811,801		3,811,801
$1.48-$2.05		4.0		1,114,318		1,114,318
Total		2.7		4,926,119		4,926,119