There is a new little (xviii, 78 pages) book titled Kodex und Kanon: Das Buch im frühen Christentum ("Codex and Canon: The Book in Early Christianity") by Martin Wallraff that is forthcoming with de Gruyter. Here is the description from the publisher's website:
"Christianity and the book – this is hardly a superficial relationship. Their histories date back to about the same period: the rise of Christianity and the widespread adoption of the codex both occurred in Late Antiquity. There are also substantive connections, for Christianity was quick to put the new medium to use – and for its part, the codex had its own share of repercussions on religion. Indeed, Christian book culture in antiquity set the stage for the Koran's passage into written form."