The thing about organics is that they can very precisely build themselves up, from a molecular level. They can take various, otherwise useless stuff like goethite and chitin and, through the power of engineering, turn it into one of the strongest biogenic materials to date.
So, graphene is this wunder mátériel we can't produce in high enough quantities and quality to be useful. Graphene can also reinforce spider silk.
I would have to worry about fewer things if any creature, I'm working with, could be reinforced with this unobtanium. The question is if it's possible for living creatures to produce it.
Here's some research material, I looked through:
...the aforementioned graphite oxide can be synthesized using the Tang-Lau method:
Unfortunately, it does involve high temperatures, which isn't good, maybe you can start by finding a relatively better alternative, or a way to reduce the required temperatures.
And yes, I mainly want to apply this to dragons, but repurposing the method for other creatures would be important too.