Infrared photoinduced force microscopy (IR PiFM) measurements were conducted at Molecular Vista Inc. on a Vista One microscope, with a PT277-XIR laser from Ekspla (Vilnius, Lithuaia) as the excitation source with a full tuning wavenumber range between 7143 cm -1 and 541 cm -1 , and a spectral line width of ~3 cm -1 . For fixed wavenumber PiFM imaging, PiF-IR spectra were first taken on the polymer brush monolayers and substrates (patterned or non-patterned), then the IR wavenumber with peak intensity in the corresponding IR range of the characteristic chemical functionality of the polymer/substrate was picked for PiFM imaging (polypeptoids: amide C=O stretching ~1660 cm -1 , PMMA: ester C=O stretching ~ 1720 cm -1 , PS: aromatic C-H stretching ~700 cm -1 , Si substrates with a native oxide layer: Si-O-Si stretching ~ 1110 cm -1 ). All images were collected with a scan speed of 0.5 Hz. PiF-IR spectra were power normalized and acquired MgCl2, pH = 8.5-9) or streptavidin solution (100 nM in 1x PBS buffer) was deposited on the nanopatterned substrate. The solution drop was then incubated on the substrate in a moisturized chamber for 1 hour, followed by corresponding rinsing protocols and drying with a N2 stream.