Property and Equipment

12 Months Ended

Dec. 31, 2016

Property, Plant and Equipment [Abstract]

Property, Plant and Equipment Disclosure [Text Block]

7. Property and Equipment

Property and equipment consisted of the following:

	Estimated	December 31,
	Useful Lives	2015		2016
Laboratory equipment	7	$	6,022,585	$	6,666,506
Office equipment and software	3 – 7		1,271,847		1,347,768
Leasehold improvements	7		408,153		424,176
Assets not in service			53,378		19,000
			7,755,963		8,457,450
Less accumulated depreciation			(4,357,565)		(5,252,373)
		$	3,398,398	$	3,205,077

Assets not in service represent new laboratory equipment, computer equipment and software that were not installed and ready to use at December 31, 2015 and 2016. The total amount of depreciation expense for the years ended December 31, 2014, 2015 and 2016 were $857,055,  $886,710 and $919,809, respectively.