As chief operating officer of BioStrut LLC, Mick Darling is responsible for helping to find space for the biotech startup. But zeroing in on the perfect spot is a challenge. Darling says he and the company’s other officers -- his brother Andrew Darling and Wei Sun -- want headquarters in Philadelphia so they can be close to Drexel University, the company’s incubator. They also want manufacturing space in the Boston area so they can be close to potential clients. And they want offices that can easily expand to house sales and marketing staff if and when they’re added. Young companies have plenty of challenges as they get off the ground, from raising capital to getting new customers. Finding the right location is just one more item on the list. And despite the booming biotech community here -- and all the support and existing infrastructure that go with it -- biotech startups aren’t immune to real estate challenges. They have needs similar to other new firms, such as finding good space at prices they can afford. But they also have requirements unique to their industry as well.