Commercially available SWCNTs were purchased from Alpha
Nano Technology Co. (Chengdu, China). SWCNTs were more
than 90% pure by dry weight, with a specific surface area
greater than 400 m2
/g, an average diameter of 1e2 nm, and
5e20 mm in the length. SWCNT stock suspension was prepared
by mixing SWCNTs in distilled water for 30 min in an
ultrasonic bath, followed by further sonication with an ultrasonic
cell disruptor (Ningbo Scientz Biotechnology Co., China)
for 1 h at a power output of 80 w. The suspension was
sonicated in the ultrasonic bath for 30 min before use to
ensure a homogeneous mixture.