Localized surface plasmon resonance (LSPR)-based sensing has found wide applications in medical diagnosis, food safety regulation and environmental monitoring. Compared with commercial propagating surface plasmon resonance (PSPR)-based sensors, LSPR ones are simple, cost-effective and suitable for measuring local refractive index changes. However, the figure of merit (FOM) values of LSPR sensors are generally 1-2 orders of magnitude smaller than those of PSPR ones, preventing the widespread use of LSPR sensors. Here we describe an array of submicrometer gold mushrooms with a FOM reaching B108, which is comparable to the theoretically predicted upper limit for standard PSPR sensors. Such a high FOM arises from the interference between Wood's anomaly and the LSPRs. We further demonstrate the array as a biosensor for detecting cytochrome c and alpha-fetoprotein, with their detection limits down to 200 pM and 15 ng ml À 1 , respectively, suggesting that the array is a promising candidate for label-free biomedical sensing.
Anderson-type polyoxometalate built-in conjugated microporous polymers were prepared via a bottom-up strategy and served as a good heterogeneous photocatalyst for the degradation of organic dyes.
Although
a plethora of nonviral gene vectors have been developed
for potential gene therapy, imageable gemini surfactants with stimuli-responsiveness
and high transfection efficiency are still scarce for gene delivery.
Herein, three gemini amphiphiles (DEDPP-4/8/12) consisting
of an aggregation-induced emission (AIE) central fluorophore: 5,6-diphenylpyrazine-2,3-diester
(DEDPP), decorated with triazole-[12]aneN3 as the hydrophilic moiety and alkyl chains of various lengths as
the hydrophobic moiety, were designed and synthesized for trackable
gene delivery via optical imaging. All three amphiphiles exhibited
ultralow critical micelle concentrations (CMCs) (up to 3.40 ×
10–6 M), prominent two-photon absorption properties,
and solvatochromic fluorescence. Gel electrophoresis assays demonstrated
that the migration of plasmid DNA was completely retarded after condensation
with these gemini amphiphiles at low concentrations (up to 10 μM).
In addition, the ester bond in these amphiphiles may facilitate vector
degradation and DNA release, in response to esterase and the acidic
environment inside cells. Upon self-assembly with DOPE to form liposomes, DEDPP-8/DOPE achieved the best transfection efficiency in
four cell lines, and the transfection efficiency of DEDPP-8/DOPE in HeLa cell lines was 23.5-fold higher than that of Lipo2000,
which is unusually high for small organic molecule-based nonviral
vectors. Furthermore, excellent transfection efficiency of DEDPP-8/DOPE was obtained in the presence of serum, and the red fluorescence
protein (RFP) gene was successfully transfected in zebrafish embryos.
Both one- and two-photon fluorescence imaging clearly demonstrated
the delivery process of plasmid DNA. This study demonstrated that
gemini-type amphiphiles composed of a two-photon fluorophore core
conjugated with triazole-[12]aneN3 via an ester bond afforded
an unprecedentedly high transfection efficiency with excellent biocompatibility,
which may provide new insights for the design and development of multifunctional
nonviral gene vectors for imageable gene delivery.
Three
nonviral gene vectors, TPA-BI-A/B/C, have been designed and synthesized by the combination
of one or two hydrophilic [12]aneN3 moieties and two-photon
fluorescent triphenylamine-benzylideneimidazolone (TPA-BI) units through
different ester linkage. Spectroscopic characterization demonstrated
that TPA-BI-A/B/C had strong
aggregation-induced emissions (AIE), large Stokes shifts (230, 284,
and 263 nm), and large two-photon absorption cross sections (δ2PA) (67, 592, and 80 GM). Gel electrophoresis indicated that
the three compounds completely condensed DNA at 15 μM in the
presence of DOPE, and showed the lipase- and pH-triggered reversible
release of DNA and the fluorescent recognition of the different lengths
of ssDNA and dsDNA. The optimal TPA-BI-C/DOPE-mediated
luciferase and GFP activity was 146% and 290% higher than those of
Lipo2000. The transfection process of DNA could be traced clearly
through one- and two-photon fluorescence spectra, and displayed in
a 3D-video. TPA-BI-C/DOPE successfully transfected the
GFP gene into zebrafish, which was superior to Lipo2000 (192%). In
conclusion, TPA-BI-C/DOPE is the first nonviral gene
vector with the abilities of pH/lipase enzyme responsiveness, one/two-photon
fluorescent tracking of intracellular delivery of DNA, and successful
transfection in vivo and in vitro, even better than Lipo2000.
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