We herein present
a three-in-one nanoplatform for sensing, self-assembly,
and cascade catalysis, enabled by cyclodextrin modified gold nanoparticles
(CD@AuNPs). Monodisperse AuNPs 15–20 nm in diameter are fabricated
in an eco-friendly way by the proposed one-step colloidal synthesis
method using CD as both reducing agents and stabilizers. First, the
as-prepared AuNPs are employed as not only scaffolds but energy acceptors
for turn-on fluorescent sensing based on guest replacement reaction.
Then, the macrocyclic supramolecule functionalized AuNPs can be controllably
assembled and form well-defined one- and two-dimensional architectures
using tetrakis(4-carboxyphenyl)porphyrin as mediator. Finally, in
addition to conventional host–guest interaction based properties,
the CD@AuNPs possess unpredictable catalytic activity and exhibit
mimicking properties of both glucose oxidase and horseradish peroxidase
simultaneously. Especially, the cascade reaction (glucose is first
catalytically oxidized and generates gluconic acid and H2O2; then the enzymatic H2O2 and
preadded TMB (3,3′,5,5′-tetramethylbenzidine) are further
catalyzed into H2O and oxTMB, respectively) is well-achieved
using the AuNPs as the sole catalyst. By employing a joint experimental–theoretical
study, we reveal that the unique catalytic properties of the CD@AuNPs
probably derive from the special topological structures of CD molecules
and the resulting electron transfer effect from the AuNP surface to
the appended CD molecules.