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

12 Months Ended

Dec. 31, 2020

Equity Incentive Plan [Member]

Stock Option Plans and Warrants to Purchase Common Stock (Tables) [Line Items]

Schedule of shares available for grant under the 2015 plan

Shares available for grant at January 1, 2020	663,709
Options granted	(520,812	)
Options forfeited	71,792
Shares available for grant at December 31, 2020	214,689

Employee Stock Options [Member]

Stock Option Plans and Warrants to Purchase Common Stock (Tables) [Line Items]

Schedule of activity under the 2005 plan and the 2015 plan

				Weighted Average
	Options			Options Exercise Price
Balance outstanding at December 31, 2018		1,022,095		$	5.32
Granted		596,740			1.09
Forfeited		(111,863	)		3.27
Balance outstanding at December 31, 2019		1,506,972		$	3.77
Granted		520,812			2.17
Forfeited		(88,222	)		13.06
Exercised		(5,758	)		1.19
Balance outstanding at December 31, 2020		1,933,804		$	2.96

Schedule of weighted-average exercise price, by price range, for outstanding options to purchase common stock

Price Range	Weighted Average Remaining Contractual Life in Years		Outstanding Options		Exercisable Options
$0.71-$2.79		8.49		1,723,180		1,099,818
$6.40-$15.60		3.42		156,394		156,394
$20.00-$39.80		2.58		54,230		54,230
Total		7.91		1,933,804		1,310,442

Share-based Payment Arrangement [Member]

Stock Option Plans and Warrants to Purchase Common Stock (Tables) [Line Items]

Schedule of share-based compensation expense

Share-based compensation	2020		2019
Research and development	$	195,560	$	143,217
General and administrative		214,373		233,122
Total	$	409,933	$	376,339

Warrants [Member]

Stock Option Plans and Warrants to Purchase Common Stock (Tables) [Line Items]

Schedule of warrant activity

	Warrants			Weighted Average Exercise Price
Balance at December 31, 2018		6,303,643		$	3.09
Granted		-			-
Exercised		-			-
Expired		(110,932	)		14.80
Balance at December 31, 2019		6,192,711		$	2.88
Granted		-			-
Exercised		(461,234	)		1.87
Expired		-			-
Balance at December 31, 2020		5,731,477		$	2.96

Schedule of remaining life, by grant date, for outstanding warrants

Grant Date	Exercise Price		Remaining Contractual Life in Years		Outstanding Warrants		Exercisable Warrants
12/16/2016	$	3.95		0.96		2,403,405		2,403,405
11/3/2017	$	2.50		1.83		49,872		49,872
4/1/2018	$	1.95		2.24		10,000		10,000
7/2/2018	$	2.25		1.01		3,268,200		3,268,200
Total	$	2.88		2.02		5,731,477		5,731,477