synthesis procedures were used without any further purifications.
Dopamine hydrochloride (CAS: 62-31-7, s, >98%),
Trizma
base (CAS: 77-86-1, s, >99%), hydrochloric acid
(CAS:
7647-01-0, l, 25%), silicon wafer (Si 100, CAS: 7440-21-3, s), titanium tetrachloride (CAS: 7550-45-0), sodium sulfate
(CAS: 7757-82-6, s), quartz (fused, thickness: 1.0
mm), and quartz/indium tin oxide (ITO) substrates (CAS: 50926-11-9)
purchased from Sigma-Aldrich and ultrapure deionized water obtained
from a Hydrolab Ultra UV system were used.