3 research outputs found
Polymeric Nanocubes Spontaneously Formed from Poly(ε-caprolactone)
A facile and economical approach was successfully developed
to
prepare polymeric nanocubes from polyÂ(ε-caprolactone) (PCL).
Nanocubes which are rarely achieved with polymer were obtained simply
by a proper thermal treatment on PCL thin film on a glass slide or
silicon wafer. The results of scanning electron microscopy (SEM) and
atomic force microscopy (AFM) observation showed that the nanocubes
were as small as ∼70 nm with high yield (up to ∼130 000
nanocubes in 1 cm<sup>2</sup> area). The combination of high-resolution
transmission electron microscopy (HRTEM) and fast Fourier transform
(FFT) demonstrated that these particles were single nanocrystals.
We suggest that the formation of these nanocubes is based on a dewetting
and crystallization mechanism. In addition, the size and yield of
nanocubes could be controlled by the solution concentration and architecture
of polymer as well as substrate. This work might not only facilitate
gaining further basic knowledge about nucleation and crystalline growth
mechanism of PCL but also provide a new way to fabricate nonspherical
polymeric nanoparticles
Surface-Enhanced Raman Scattering Active Plasmonic Nanoparticles with Ultrasmall Interior Nanogap for Multiplex Quantitative Detection and Cancer Cell Imaging
Due to its large enhancement effect,
nanostructure-based surface-enhanced
Raman scattering (SERS) technology had been widely applied for bioanalysis
and cell imaging. However, most SERS nanostructures suffer from poor
signal reproducibility, which hinders the application of SERS nanostructures
in quantitative detection. We report an etching-assisted approach
to synthesize SERS-active plasmonic nanoparticles with 1 nm interior
nanogap for multiplex quantitative detection and cancer cell imaging.
Raman dyes and methoxy polyÂ(ethylene glycol) thiol (mPEG–SH)
were attached to gold nanoparticles (AuNPs) to prepare gold cores.
Next, Ag atoms were deposited on gold cores in the presence of Pluronic
F127 to form a Ag shell. HAuCl<sub>4</sub> was used to etch the Ag
shell and form an interior nanogap in Au@AgAuNPs, leading to increased
Raman intensity of dyes. SERS intensity distribution of Au@AgAuNPs
was found to be more uniform than that of aggregated AuNPs. Finally,
Au@AgAuNPs were used for multiplex quantitative detection and cancer
cell imaging. With the advantages of simple and rapid preparation
of Au@AgAuNPs with highly uniform, stable, and reproducible Raman
intensity, the method reported here will widen the applications of
SERS-active nanoparticles in diagnostics and imaging
Simple and Rapid Functionalization of Gold Nanorods with Oligonucleotides Using an mPEG-SH/Tween 20-Assisted Approach
DNA conjugated gold nanorods (AuNRs)
are widely applied for nanostructure
assembly, gene therapy, biosensing, and drug delivery. However, it
is still a great challenge to attach thiolated DNA on AuNRs, because
the positively charged AuNRs readily aggregate in the presence of
negatively charged DNA. This article reports an mPEG-SH/Tween 20-assisted
method to load thiolated DNA on AuNRs in 1 h. Tween 20 and mPEG-SH
are used to synergistically displace CTAB on the surface of AuNRs
by repeated centrifugation and resuspension, and thiolated DNA are
attached to AuNRs in the presence of 1 M NaCl, 100 mM MgCl<sub>2</sub>, or 100 mM citrate. AuNRs with different sizes and aspect ratios
can be functionalized with DNA by this method. The number of DNA loaded
on each AuNR can be easily controlled by the concentrations of mPEG-SH
and Tween 20 or the ratio between DNA and AuNR. Functionalized AuNRs
were used for nanoparticle assembly and cancer cell imaging to confirm
that DNA anchored on the surface of AuNRs retains its hybridization
and molecular recognition capability. The new method is easy, rapid,
and robust for the preparation of DNA functionalized AuNRs for a variety
of applications such as cancer therapy, drug delivery, self-assembly,
and imaging