That bolt is called a caliper pin bolt (or slide pin bolt). It's special, but you can buy one at any auto parts store. It will be found under the category of brake hardware. I highly do not recommend using a standard bolt for that application.
When installing, grease the body of the bolt with hi temp synthetic brake grease, use blue Loctite on the threads and torque the bolt to around 30 ft lbs.
Thanks for the info.