CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($)	Jun. 30, 2017	Dec. 31, 2016
Current assets:
Cash and cash equivalents	$ 7,783,891	$ 13,915,094
Short-term investments	0	23,978,022
Accounts receivable	157,445	100,460
Prepaid expenses and other assets	713,913	956,616
Total current assets	8,655,249	38,950,192
Property and equipment, net	3,321,532	3,826,915
Other assets	583,973	1,173,304
Total Assets	12,560,754	43,950,411
Current liabilities:
Accounts payable	602,738	1,130,536
Accrued expenses	4,929,631	4,021,365
Deferred rent	285,246	285,246
Current portion of long-term debt (in default)	1,644,567	2,360,109
Total current liabilities	7,462,182	7,797,256
Long-term debt, less current portion	0	14,176,359
Derivative financial instruments—warrants	350,862	834,940
Deferred rent, net of current portion	1,236,941	1,373,717
Total Liabilities	9,049,985	24,182,272
Commitments and contingencies (Note 9)
Stockholders’ equity
Preferred stock, $0.001 par value, 20,000,000 shares authorized; 60,600 shares outstanding at June 30, 2017 and December 31, 2016; designated as Series A Convertible Preferred Stock with liquidation preference of $606,000 at June 30, 2017 and December 31, 2016	60	60
Common stock, $0.0001 par value, 150,000,000 shares authorized; 31,076,872 and 30,696,791 shares issued and outstanding at June 30, 2017 and December 31, 2016, respectively	3,108	3,070
Additional paid-in capital	169,693,921	167,890,984
Accumulated other comprehensive loss	(13,650)	(10,773)
Accumulated deficit	(166,172,670)	(148,115,202)
Total stockholders’ equity	3,510,769	19,768,139
Total liabilities and stockholders’ equity	$ 12,560,754	$ 43,950,411

Carrying value as of the balance sheet date of liabilities incurred (and for which invoices have typically been received) and payable to vendors for goods and services received that are used in an entity's business. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer).

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount due from customers or clients, within one year of the balance sheet date (or the normal operating cycle, whichever is longer), for goods or services (including trade receivables) that have been delivered or sold in the normal course of business, reduced to the estimated net realizable fair value by an allowance established by the entity of the amount it deems uncertain of collection.