What is the fine-grained topic of the following text: Working from a 'bottom-up'approach, by studying molecules of ever growing complexity up to full biological molecules, the fundemental biophysical processes that govern the photostability of hese complicated biomolecules (such as whole DNA or biological/synthetic sunscreens) can be understood. Only return the topic.
Understanding the photostability of complex biomolecules through a bottom-up approach.