Fig. 3.

The stability of Lf-PEG-AuNP according to exposure to the gastrointestinal tract environments. (a) Thermal images of AuNP and Lf-PEG-AuNP by PTT laser irradiation after exposure at pH 2 and pH 5 for 12 h. (b) Thermal images of AuNP and Lf-PEG-AuNP by PTT laser irradiation after exposure at pH 2 and pH 5 at each incubation time. Data were expressed as means ± SEM (n = 5). (c) UV–Vis absorption spectrum of AuNP and Lf-PEG-AuNP after exposure at pH 2 and pH 5 for 12 h. Peak shift from 532-nm to 600-nm wavelength. (d) UV–Vis absorption spectrum of Lf-PEG-AuNP after exposure at pH 2 for 2 h and serial exposure at pH 5 for 8 h. (e) Proteolytic degradation of Lf and Lf-PEG during incubation time with pepsin enzyme. (f) The resistance of Lf and Lf-PEG from pepsin enzyme through the densitometrically analysis of the band at Fig. 3e.