Fig. 6.
AuNPs formation in physiological solution. (A) A 100 μg/mL solution of HAuCl4 and five different concentrations of HEPES in the physiological solution were tested (0, 5, 10, 15, and 20 mM) at 37 °C and pH 7.4. Formation of AuNPs was observable after 30 min and remained after 24 h. (B) UV–vis spectra of AuNPs formed in the physiological solution with HEPES 20 mM (37 °C, pH 7.4), the normal concentration of HEPES used in ex vivo experiments with isolated rings. Maximum absorption at 557 nm indicates the surface resonance plasmon of AuNPs. (C) TEM micrograph of AuNPs formed in HEPES solution.