adsorption/desorption isotherm (Figure 2A). The MSNs have
well-defined mesoporous nanopores with an average diameter
of ∼3.86 nm (Figure 2B) and high surface areas of 1136.74 m2/
g (Supporting Information, Table S1). After cargo loading and
α-CD capping, there was an obvious decrease in the pore
volume and pore diameter of particles (Figure 2B), indicating
that the nanopores were successfully plugged up by the
incorporated α-CD rings. Besides nitrogen adsorption/
desorption isotherm, zeta potential and FT-IR analyses were
also employed to monitor the modification of the MSNs. From
the zeta potential summarized in Table 1, the blank MSNs were
negatively charged with a zeta potential of −24.76 mV, which
jumped to +21.04 mV after amine modification. After reaction
with propargyl bromide, the zeta potential decreased to +5.23
mV since most of the ionized amine groups had changed into
un-ionized amide groups. Further conjugation with azido-
GFLGR7RGDS, which is rich in positively charged arginine
DOI: 10.1021/acsami.5b00752