My solution was to cover these favorite reads of mine with fabric. The method is mega simple. Just do what you did to your Biology textbook, but instead of a brown paper grocery bag, use fabric.
Yikes, those are some bad looking bindings. In my defense, the top one, wasn't read to death, but instead was in the wrong place at the time of a roof leak. It saved my grandmother's dresser and for that I am thankful to it.
Make a sleeve around front and back cover, like above.
Before you slide your book in, add details like name tags, ribbons to tie it all closed-- the above pink one wraps around twice and gives it a real Laura Ingalls feel. Once you get these frills in place topstitch your edges and slide book in. You're ready to go forth with protected pages. Quick update, I did this two months ago and my books are holding up great.
Extra points if you can guess which author I read and carry in my purse like an epi-pen for boredom.