Chemically-triggered drug delivery systems (DDSs) have been extensively studied as they do not require specialized equipment to deliver the drug and can deeply penetrate human tissue. However, their syntheses are complicated and they tend to be cytotoxic, which restricts their clinical utility. In this work, the self-regulated drug loading and release capabilities of peptide-protected gold nanoclusters (Pep-Au NCs) are investigated using vancomycin (Van) as the model drug. Gold nanoclusters (Au NCs) coated with a custom-designed pentapeptide are synthesized as drug delivery nanocarriers and loaded with Van - a spontaneous process reliant on the specific binding between Van and the custom-designed peptide. The Van-loaded Au NCs show comparable antimicrobial activity with Van on its own, and the number of Van released by the Pep-Au NCs is found to be proportional to the amount of bacteria present. The controlled nature of the Van release is very encouraging, and predominantly due to the stronger binding affinity of Van with bacteria than that with Au NCs. In addition, these fluorescent Au NCs could also be used to construct temperature sensors, which enable the in vitro and in vivo bioimaging.
Two new silver nanoclusters, formulated as Ag42(SBut)24 and Ag61(SC6H11)40Cl were prepared by a NaSbF6-mediated two-phase ligand exchange method. A size conversion from Ag42 to Ag61 were achieved via cyclohexanethiol etching.
Precise atomic structure of metal nanoclusters (NCs) is fundamental for elucidating the structure–property relationships and the inherent size‐evolution principles. Reported here is the largest known FCC‐based (FCC=face centered cubic) silver nanocluster, [Ag100(SC6H33,4F2)48(PPh3)8]−: the first all‐octahedral symmetric nesting Ag nanocluster with a four‐layered Ag6@Ag38@Ag48S24@Ag8S24P8 structure, consistent symmetry elements, and a unique rhombicuboctahedral morphology distinct from theoretical predictions and previously reported FCC‐based Ag clusters. DFT studies revealed extensive interlayer interactions and degenerate frontier orbitals. The FCC‐based Russian nesting doll model constitutes a new platform for the study of the size‐evolution principles of Ag NCs.
In
this work, we report the synthesis and crystal structure of
Au38–x
Cu
x
(2,4-DMBT)24 (x = 0–6,
2,4-DMBTH = 2,4-dimethylbenzenethiol) alloy nanocluster
for the first time. A variety of characterizations including ESI-MS,
TGA, and XPS reveal the composition as Au38–x
Cu
x
(2,4-DMBT)24 (x = 0–6). The single crystal structure
has been determined by an X-ray single crystal diffractometer. From
the anatomy of the structure, a bi-icosahedral Au23 core
is protected by six dimeric [−SR–M–SR–M–SR−]
units (M = Cu/Au) and three monomeric [−SR–Au–SR−]
units. It is interesting that all the Cu atoms are selectively doped
in the motifs of the Au38–x
Cu
x
(2,4-DMBT)24 nanocluster.
This phenomenon is distinct from the exclusive core doping of the
Ag atoms in the previously reported Au38–x
Ag
x
alloy. Both the experimental
results and DFT calculations of UV–vis spectra imply that the
optical property of the Au38–x
Cu
x
(2,4-DMBT)24 nanocluster
is consistent with that of the Au38(2,4-DMBT)24 nanocluster, because the Cu dopants make little contribution
to the frontier orbitals of the alloy NC.
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