62 research outputs found
In-Channel Printing-Device Opening Assay for Micropatterning Multiple Cells and Gene Analysis
Herein we report an easy but versatile
method for patterning different
cells on a single substrate by using a microfluidic approach that
allows not only spatial and temporal control of multiple microenvironments
but also retrieval of specific treated cells to profile their expressed
genetic information at around 10-cell resolution. By taking advantages
of increased surface area of gold nanoparticles on a poly(dimethylsiloxane)
(PDMS) coated substrate, cell adhesive-promotive protein, human fibronectin
(hFN) can be significantly accumulated on designed regions where cells
can recognize the protein and spread out. Moreover, the whole device
can be easily opened by hand without any loss of patterned cells which
could be retrieved by mouth-pipet. Consequently, we demonstrate the
possibility of analyzing the difference of gene expression patterns
between wild type MCF-7 cell and MCF/Adr (drug-resistant cell line)
from less than 400 cells in total for a single comprehensive assay,
including parallel experiments, controls, and multiple dose treatments.
Certain genes, especially the P-glycoprotein coding gene (ABCB1),
show high expression level in resistant cells compared with the wild
type, suggesting a possible pathway that may contribute to the antidrug
mechanism
Chemical Etching of Bovine Serum Albumin-Protected Au25 Nanoclusters for Label-Free and Separation-Free Ratiometric Fluorescent Detection of Tris(2-carboxyethyl)phosphine
This study describes
a novel ratiometric fluorescent sensor based
on chemical etching of gold nanocluster (GNCs) for label-free, separation-free
determination of tris(2-carboxyethyl)phosphine (TCEP). TCEP was discovered
to exhibit unusual chemical behavior toward fluorescent gold nanoclusters:
it quenched the red fluorescent emission of the bovine serum album
(BSA)-protected GNCs (GNCs@BSA) and simultaneously restored the blue
fluorescent emission of the dityrosine (diTyr) residues of the BSA
ligand. The TCEP-induced quenching of the fluorescent GNCs@BSA was
investigated with the UV–vis adsorption spectrum, the matrix-assisted
laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS),
inductively coupled plasma-mass spectrometry (ICP-MS) and X-ray photoelectron
spectroscopy (XPS), revealing the chemical etching of the gold(0)
core of the GNCs@BSA by TCEP. Furthermore, the ratio of the blue fluorescence
intensity of the diTyr to the red fluorescence intensity of the GNCs@BSA
was found to be dependent on TCEP concentration and showed a linear
relationship in the TCEP concentration range of 500 nM to 50, 000
nM (<i>R</i><sup>2</sup> = 0.9943) with a limit of detection
(LOD) of 130 nM, achieving the higher sensitivity over previous reports.
This ratiometric sensor also showed superior selectivity for TCEP
over certain common interferences including glutathione, 20 kinds
of natural amino acids, and the oxidized form of TCEP. With the developed
ratiometric method, the deproteinized human serum samples spiked with
TCEP were analyzed with satisfactory results. In addition, it is worth
noting that compared with conventional ratiometric fluorescent sensors,
the ratiometric sensor developed in this study does not require external
fluorophores, avoiding the additional derivation procedures
Intracellular MicroRNA Imaging and Specific Discrimination of Prostate Cancer Circulating Tumor Cells Using Multifunctional Gold Nanoprobe-Based Thermophoretic Assay
Circulating tumor cells (CTCs) have emerged as powerful
biomarkers
for diagnosis of prostate cancer. However, the effective identification
and concurrently accurate imaging of CTCs for early screening of prostate
cancer have been rarely explored. Herein, we reported a multifunctional
gold nanoprobe-based thermophoretic assay for simultaneous specific
distinguishing of prostate cancer CTCs and sensitive imaging of intracellular
microRNA (miR-21), achieving the rapid and precise detection of prostate
cancer. The multifunctional gold nanoprobe (GNP-DNA/Ab) was modified
by two types of prostate-specific antibodies, anti-PSMA and anti-EpCAM,
which could effectively recognize the targeting CTCs, and meanwhile
linked double-stranded DNA for further visually imaging intracellular
miR-21. Upon the specific internalization of GNP-DNA/Ab by PC-3 cells,
target aberrant miR-21 could displace the signal strand to recover
the fluorescence signal for sensitive detection at the single-cell
level, achieving single PC-3 cell imaging benefiting from the thermophoresis-mediated
signal amplification procedure. Taking advantage of the sensitive
miR-21 imaging performance, GNP-DNA/Ab could be employed to discriminate
the PC-3 and Jurkat cells because of the different expression levels
of miR-21. Notably, PC-3 cells were efficiently recognized from white
blood cells, exhibiting promising potential for the early diagnosis
of prostate cancer. Furthermore, GNP-DNA/Ab possessed good biocompatibility
and stability. Therefore, this work provides a great tool for aberrant
miRNA-related detection and specific discrimination of CTCs, achieving
the early and accurate diagnosis of prostate cancer
A cloud-based X73 ubiquitous mobile healthcare system: design and implementation
Based on the user-centric paradigm for next generation networks, this paper describes a ubiquitous mobile healthcare (uHealth) system based on the ISO/IEEE 11073 personal health data (PHD) standards (X73) and cloud computing techniques. A number of design issues associated with the system implementation are outlined. The system includes a middleware on the user side, providing a plug-and-play environment for heterogeneous wireless sensors and mobile terminals utilizing different communication protocols and a distributed "big data" processing subsystem in the cloud. The design and implementation of this system are envisaged as an efficient solution for the next generation of uHealth systems
Hidden Dityrosine Residues in Protein-Protected Gold Nanoclusters
The
protein ligand shells of fluorescent protein-protected gold
nanoclusters play an important role in the physiochemical properties
and sensing applications of the nanoclusters. Recently, more and more
attention has been paid to the investigation of the changes in the
protein structure elements induced by the introduction of the nanoclusters
in the proteins. In this work, the strategy of removal of the encapsulated
gold nanoclusters from the protein ligand cages has been proposed,
producing the “hollow” (or possibly “imprinted”)
proteins for investigations for the first time. Nontoxic cysteamine
was used as the etchant of the gold nanoclusters. With bovine serum
albumin, lysozyme, and ovalbumin as model proteins, it was found that
the luminescent dityrosine cross-links exist in the protein-protected
gold nanoclusters, however, inner filter effect caused by the gold
nanoclusters hide them
Electrochemically Mediated Surface-Initiated de Novo Growth of Polymers for Amplified Electrochemical Detection of DNA
The
development of convenient and efficient strategies without involving
any complex nanomaterials or enzymes for signal amplification is of
great importance in bioanalytical applications. In this work, we report
the use of electrochemically mediated surface-initiated atom transfer
radical polymerization (SI-eATRP) as a novel amplification strategy
based on the de novo growth of polymers (dnGOPs) for the electrochemical
detection of DNA. Specifically, the capture of target DNA (tDNA) by
the immobilized peptide nucleic acid (PNA) probes provides a high
density of phosphate groups for the subsequent attachment of ATRP
initiators onto the electrode surface by means of the phosphate-Zr<sup>4+</sup>-carboxylate chemistry, followed by the de novo growth of
electroactive polymer via the SI-eATRP. De novo growth of long polymeric
chains enables the labeling of numerous electroactive probes, which
in turn greatly improves the electrochemical response. Moreover, it
circumvents the slow kinetics and poor coupling efficiency encountered
when nanomaterials or preformed polymers are used and features sufficient
flexibility and simplicity in controlling the degree of signal amplification.
Under optimal conditions, it allows a highly sensitive and selective
detection of tDNA within a broad linear range from 0.1 fM to 0.1 nM
(<i>R</i><sup>2</sup> = 0.996), with the detection limit
down to 0.072 fM. Compared with the unamplified method, more than
1.2 × 10<sup>6</sup>-fold sensitivity improvement in DNA detection
can be achieved. By virtue of its simplicity, high efficiency, and
cost-effectiveness, the proposed dnGOPs-based signal amplification
strategy holds great potential in bioanalytical applications for the
sensitive detection of biological molecules
Ion Permeability of Polydopamine Films Revealed Using a Prussian Blue-Based Electrochemical Method
Polydopamine
(PDA) is fast becoming a popular surface modification
technique. Detailed understanding of the ion permeability properties
of PDA films will improve their applications. Herein, we report for
the first time the thickness-independent ion permeability of PDA films
using a Prussian blue (PB)-based electrochemical method. In this method,
PDA films are deposited via ammonium persulfate-induced dopamine polymerization
onto a PB electrode. The ion permeability of the PDA films can thus
be detected by observing the changes in electrochemical behaviors
of the PB coated by PDA films. On the basis of this method, it was
unexpectedly found that the PDA films with thickness greater than
45 nm (e.g., ∼60 and ∼113 nm) can exhibit pH-switchable
but thickness-insensitive permeability to monovalent cations such
as potassium and sodium ions. These observations clearly indicate
the presence of a continuous network of interconnected intermolecular
voids within PDA films, regardless of film thickness
Fully Integrated Ratiometric Fluorescence Enrichment Platform for High-Sensitivity POC Testing of Salivary Cancer Biomarkers
The point-of-care (POC) testing of
cancer biomarkers
in saliva
with both high sensitivity and accuracy remains a serious challenge
in modern clinical medicine. Herein, we develop a new fully integrated
ratiometric fluorescence enrichment platform that utilizes acoustic
radiation forces to enrich dual-emission sandwich immune complexes
for a POC visual assay. As a result, the color signals from red and
green fluorescence (capture probe and report probe, respectively)
are enhanced by nearly 10 times, and colorimetric sensitivity is effectively
improved. When illuminated using a portable UV lamp, the fluorescence
color changing from red to green can be clearly seen with the naked
eye, which allows a semiqualitative assessment of the carcinoembryonic
antigen (CEA) level. In combination with a homemade smartphone-based
portable device, cancer biomarkers like CEA are quantified, achieving
a limit of detection as low as 0.012 ng/mL. We also directly quantify
CEA in human saliva samples to investigate the reliability of this
fully integrated platform, thus validating the usefulness of the proposed
strategy for clinical diagnosis and home monitoring of physical conditions
Synergistic Inhibitory Effect of GQDs–Tramiprosate Covalent Binding on Amyloid Aggregation
Inhibiting
the amyloid aggregation is considered to be an effective
strategy to explore possible treatment of amyloid-related diseases
including Alzheimer’s disease, Parkinson’s disease,
and type II diabetes. Herein, a new high-efficiency and low-cytotoxicity
Aβ aggregation inhibitors, GQD-T, was designed through the combination
of two Aβ aggregation inhibitors, graphene quantum dots (GQDs)
and tramiprosate. GQD-T showed the capability of efficiently inhibiting
the aggregation of Aβ peptides and rescuing Aβ-induced
cytotoxicity due to the synergistic effect of the GQDs and tramiprosate.
In addition, the GQD-T has the characteristics of low toxicity and
great biocompatibility. It is believed that GQD-T may be a potential
candidate for an Alzheimer’s drug and this work provides a
new strategy for exploring Aβ peptide aggregation inhibitors
Fully Integrated Ratiometric Fluorescence Enrichment Platform for High-Sensitivity POC Testing of Salivary Cancer Biomarkers
The point-of-care (POC) testing of
cancer biomarkers
in saliva
with both high sensitivity and accuracy remains a serious challenge
in modern clinical medicine. Herein, we develop a new fully integrated
ratiometric fluorescence enrichment platform that utilizes acoustic
radiation forces to enrich dual-emission sandwich immune complexes
for a POC visual assay. As a result, the color signals from red and
green fluorescence (capture probe and report probe, respectively)
are enhanced by nearly 10 times, and colorimetric sensitivity is effectively
improved. When illuminated using a portable UV lamp, the fluorescence
color changing from red to green can be clearly seen with the naked
eye, which allows a semiqualitative assessment of the carcinoembryonic
antigen (CEA) level. In combination with a homemade smartphone-based
portable device, cancer biomarkers like CEA are quantified, achieving
a limit of detection as low as 0.012 ng/mL. We also directly quantify
CEA in human saliva samples to investigate the reliability of this
fully integrated platform, thus validating the usefulness of the proposed
strategy for clinical diagnosis and home monitoring of physical conditions
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