Fair Value of Financial Instruments (Tables)

6 Months Ended

Jun. 30, 2015

Financial Assets and Liabilities Measured at Fair Value on Recurring Basis

The following table provides information about the Company’s financial assets and liabilities measured at fair value on a recurring basis at June 30, 2015 and December 31, 2014, respectively:

	Balance at June 30, 2015		Level 1		Level 2		Level 3		Balance at December 31, 2014		Level 1		Level 2		Level 3
Asset included in:
Cash and cash equivalents
Money market securities	$	9,666,594	$	9,666,594			$	—	$	3,608,890	$	3,608,890	$	—	$	—
Corporate debt securities	$	1,499,462	$	—	$	1,499,462	$	—	$	—	$	—	$	—	$	—
Investments at fair value
U.S. government obligations	$	3,307,680	$	3,307,680	$	—	$	—	$	—	$	—	$	—	$	—
U.S. government agency obligations	$	14,717,062	$	—	$	14,717,062	$	—	$	—	$	—	$	—	$	—
Corporate debt securities	$	14,844,827	$	—	$	14,844,827	$	—	$	—	$	—	$	—	$	—
Liabilities:
Growth Term Loan warrants	$	—	$	—	$	—	$	—	$	301,508	$	—	$	—	$	301,508
Preferred Stock warrants	$	—	$	—	$	—	$	—	$	429,035	$	—	$	—	$	429,035

Summary of Fair Value Assessment of Warrant Liability Inputs using Black Sholes Option Pricing Model

The December 31, 2014 fair value assessments used the Black-Sholes option pricing model using the following assumptions:

	December 31, 2014
Fair value of Series B/C/D Stock and Series E Stock shares on grant date or measurement date	$0.14 - $0.22
Exercise price	$0.01 - $0.346
Expected risk-free interest rate		1.20%
Expected volatility		70%
Expected term	4.1 years
Expected dividend yield	0 - 8%

Reconciliation of Beginning and Ending Liabilities Measured at Fair Value on Recurring Basis

A reconciliation of the beginning and ending liabilities measured at fair value on a recurring basis using Level 3 inputs for June 30, 2015 and June 30, 2014 are as follows:

	June 30, 2015			June 30, 2014
Beginning balance	$	730,543		$	44,120
Issuance of Series E Preferred Stock Warrants		—			1,890,000
Exercise of Series E Preferred Stock Warrants		(4,116	)		(1,890,000	)
Exercise of Series D Preferred Stock Warrants		(91,798	)		—
Reclassification of Series C-2 Warrants to Common Stock Warrants		(555	)		—
Reclassification of Growth Term Loan Warrants to Common Warrants		(229,550	)		—
Issuance of Convertible Note Warrants		741,828			—
Reclassification of Convertible Note Warrants to Common Stock Warrants		(1,386,035	)		—
Change in preferred stock warrant valuation		239,683			56,322
Ending balance	$	—		$	100,442