Fig. 3From: Mucoadhesive, antioxidant, and lubricant catechol-functionalized poly(phosphobetaine) as biomaterial nanotherapeutics for treating ocular drynessMucoadhesion evaluation of as-prepared polymers. XPS spectra of the modified substrates: Core-level binding energy of elements: P2p (a), N1s (b), C1s (c), and O1s (d). Changes in frequency Δf with time were recorded with eQCM for mucin deposition (e) and the interaction between polymers on mucin layer (f)Back to article page