Once most likely wont hurt it. I do not recommend do this all the time though. Most people do not relize that the fuel is what keeps the fuel pump cool. The motor sits about half way from the bottom of the tank so running the car with less than half a tank all the time will drasticaly shorten the life of the pump.
On my van I keep the tank over half because it does not like running with the fuel below where the pump sits. By keeping the fuel above 1/2 tank I am buying time before I have to get the silly thing changed.
Another note, I do not like the E-85 fuel. Reason is that you do not get the same mileage from it as you do gasoline. Unless the price of it is about 20 to 25 percent cheaper than gas you are not getting the best value for your money. The E-10 we are forced to buy is not the best either, I prefer no e fuel myself. Though it can lower the emissions from a vehicle it also lower its mpg. I just do no agree with the so called "benifits" of running any E-fuel at this time. Yes the E-10 we are forced to buy does cut about 5 to 10 percent of the cars emissions but it also cuts the mpg by 5 to 10 percent as well. So now I use more fuel to get to where I want to be, just where does it make since to use more fuel? Would not using less fuel actually save the emissions better than burning more fuel?