Fig. 4. Spectroscopic studies of the pH-dependent fluorescence of NBC-labelled PCysMA brushes and NBC-labelled POEGMA brushes on glass slides using a spectrofluorimeter. (a) Schematic experimental set-up. A brush-functionalized glass slide was placed in a cuvette at an angle of ∼140° to the excitation beam. The cuvette was filled with 0.1 M phosphate buffer adjusted to the desired pH and emission spectra were recorded at an excitation wavelength of 543 nm. (b) Top: emission spectra obtained for ∼20 nm POEGMA brushes ([OEGMA]/[NBC] = 600) at pH 5.2–8.0. Bottom: emission spectra obtained for ∼10 nm PCysMA brushes ([PCysMA]/[NBC] = 460). (c) Dependence of the I₆₅₀/I₇₀₀ intensity ratio for PCysMA and POEGMA as a function of solution pH. Spectrophotometer settings: excitation slit = 10 nm, emission slit = 20 nm. Scan rate – 1200 nm min^–1. PMT = 950 V.