Table 3. Review of Surface Characterization Techniques Used in This Study Highlighting Their Resolution, Advantages and Limitations^{30,31,34,35,41}.

surface characterization technique	detection	detection limit	advantages	limitations	key references	# of publications (2012–2022)
ATR-FTIR	functional groups	8–15 μm	simple, quick and accessible	sample is often damaged when pressing against the diamond crystal ATR	Lanzarotta, 201530	2241
		0.17%, 1700 ppm
nanoFTIR	functional groups	10–30 nm	simultaneous IR spectra and AFM data acquisition providing information on the presence and location of specific functional groups	not suitable for molecules smaller than proteins such as peptides	Amenabar et al., 201331	20
XPS	elements	0.1–1 At %	provides qualitative and quantitative information about the chemical composition of a material	lack of molecular specificity	Shard, 201441	610
		1 μm
ToF-SIMS	ions	∼2 nm	allows precise characterization of the chemical composition and distribution of an analyte on the surface	quality of data is strongly dependent on the topography of the surface, features of the order of microns can lead to lateral distortion and shadowing of the image	Taylor et al., 201834	45
		10 ng/cm2
QCM-D	mass	∼1 ng/cm2	allows to monitor real-time changes in the surface deposited mass and viscoelastic properties	molecules need to be immobilized and quantified on quartz crystal which might not resemble the real sample surface	Baio et al., 202035	76