68 research outputs found
Construction of AIEgens-Based Bioprobe with Two Fluorescent Signals for Enhanced Monitor of Extracellular and Intracellular Telomerase Activity
Detections of telomerase
activity in vitro and in living cells
are of great importance for clinical diagnosis of cancer. In this
work, an AIEgens-based bioprobe with two fluorescent signals for enhanced
monitor of extracellular and intracellular telomerase activity is
designed. After addition of telomerase, two positively charged AIEgens
(Silole-R and TPE-H) bind to quencher group labeled primer (QP) and
the extension repeated units, leading enhancement of two telomerase-triggered
fluorescent signals. Furthermore, by combination the wider linear
range in vitro and lower background in living cells imaging, the bioprobe
is used to detect telomerase extracted from various cell lines (MCF-7,
HeLa, E-J, and HLF), 50 bladder cancer patientsâ urine samples,
10 normal peopleâs urine samples, and also applied in mapping
telomerase activity inside living cells (MCF-7, HeLa, MDA-MB-231,
and HT1080). The results show that this well-designed strategy can
successfully detect telomerase activity in vitro and in living cells
with high sensitivity, indicating the potential application of this
method in cancer cells bioimaging and clinical cancer diagnosis
Highly-Efficient Gating of Solid-State Nanochannels by DNA Supersandwich Structure Containing ATP Aptamers: A Nanofluidic IMPLICATION Logic Device
Integrating biological components into artificial devices
establishes
an interface to understand and imitate the superior functionalities
of the living systems. One challenge in developing biohybrid nanosystems
mimicking the gating function of the biological ion channels is to
enhance the gating efficiency of the man-made systems. Herein, we
demonstrate a DNA supersandwich and ATP gated nanofluidic device that
exhibits high ONâOFF ratios (up to 10<sup>6</sup>) and a perfect
electric seal at its closed state (âŒGΩ). The ONâOFF
ratio is distinctly higher than existing chemically modified nanofluidic
gating systems. The gigaohm seal is comparable with that required
in ion channel electrophysiological recording and some lipid bilayer-coated
nanopore sensors. The gating function is implemented by self-assembling
DNA supersandwich structures into solid-state nanochannels (open-to-closed)
and their disassembly through ATPâDNA binding interactions
(closed-to-open). On the basis of the reversible and all-or-none electrochemical
switching properties, we further achieve the IMPLICATION logic operations
within the nanofluidic structures. The present biohybrid nanofluidic
device translates molecular events into electrical signals and indicates
a built-in signal amplification mechanism for future nanofluidic biosensing
and modular DNA computing on solid-state substrates
Bioelectrochemical Switches for the Quantitative Detection of Antibodies Directly in Whole Blood
The development of rapid, low-cost point-of-care approaches
for
the quantitative detection of antibodies would drastically impact
global health by shortening the delay between sample collection and
diagnosis and by improving the penetration of modern diagnostics into
the developing world. Unfortunately, however, current methods for
the quantitative detection of antibodies, including ELISAs, Western
blots, and fluorescence polarization assays, are complex, multiple-step
processes that rely on well-trained technicians working in well-equipped
laboratories. In response, we describe here a versatile, DNA-based
electrochemical âswitchâ for the rapid, single-step
measurement of specific antibodies directly in undiluted whole blood
at clinically relevant low-nanomolar concentrations
Facile Probe Design: Fluorescent Amphiphilic Nucleic Acid Probes without Quencher Providing Telomerase Activity Imaging Inside Living Cells
Nowadays,
the probe with fluorophore but no quencher is promising
for its simple preparation, environmental friendliness, and wide application
scope. This study designs a new amphiphilic nucleic acid probe (ANAP)
based on aggregation-caused quenching (ACQ) effect without any quencher.
Upon binding with targets, the dispersion of hydrophobic part (conjugated
fluorene, CF) in ANAP is enhanced as a signal-on model for proteins,
nucleic acids, and small molecules detection or the aggregation of
CF is enhanced as a signal-off model for ion detection. Meanwhile,
because of the high specificity of ANAP, a one-step method is developed
powerfully for monitoring the telomerase activity not only from the
cell extracts but also from 50 clinic urine samples (positive results
from 45 patients with bladder cancer and negative results from 5 healthy
people). ANAPs can also readily enter into cells and exhibit a good
performance for distinguishing natural tumor cells from the tumor
cells pretreated by telomerase-related drugs or normal cells. In contrast
to our previous results (Anal. Chem. 2015, 87, 3890â3894), the present
CF is a monomer which is just the structure unit of the previous fluorescent
polymer. Since the accurate molecular structure and high DNA/CF ratio
of the present CF, these advanced experiments obtain an easier preparation
of probes, an improved sensitivity and specificity, and broader detectable
targets
Facile, Fast-Responsive, and Photostable Imaging of Telomerase Activity in Living Cells with a Fluorescence Turn-On Manner
In situ detecting and monitoring
intracellular telomerase activity
is significant for cancer diagnosis. In this work, we report a facile
and fast-responsive bioprobe for in situ detection and imaging of
intracellular telomerase activity with superior photostability. After
transfected into living cells, quencher group labeled TS primer (QP)
can be extended in the presence of intracellular telomerase. Positive
charged TPE-Py molecules (AIE dye) will bind to the primer as well
as extension repeated units, producing a telomerase activity-related
turn-on fluorescence signal. By incorporating positive charged AIE
dye and substrate oligonucleotides, in situ light-up imaging and detection
of intracellular telomerase activity were achieved. This strategy
exhibits good performance for sensitive in situ tracking of telomerase
activity in living cells. The practicality of this facile and fast-responsive
telomerase detection method was demonstrated by using it to distinguish
tumor cells from normal cells and to monitor the change of telomerase
activity during treatment with antitumor drugs, which shows its potential
in clinical diagnostic and therapeutic monitoring
Photoactivated Specific mRNA Detection in Single Living Cells by Coupling âSignal-onâ Fluorescence and âSignal-offâ Electrochemical Signals
The
spatiotemporal detection of a target mRNA in a single living
cell is a major challenge in nanoscience and nanomedicine. We introduce
a versatile method to detect mRNA at a single living cell level that
uses photocleavable hairpin probes as functional units for the optical
(fluorescent) and electrochemical (voltammetric) detection of MnSOD
mRNA in single MCF-7 cancer cells. The fluorescent probe is composed
of an ortho-nitrophenylphosphate ester functionalized hairpin that
includes the FAM fluorophore in a caged configuration quenched by
Dabcyl. The fluorescent probe is further modified with the AS1411
aptamer to facilitate the targeting and internalization of the probe
into the MCF-7 cells. Under UV irradiation, the hairpin is cleaved,
leading to the intracellular mRNA toehold-stimulated displacement
of the FAM-functionalized strand resulting in a switched-on fluorescence
signal upon the detection of the mRNA in a single cell. In addition,
a nanoelectrode functionalized with a methylene blue (MB) redox-active
photocleavable hairpin is inserted into the cytoplasm of a single
MCF-7 cell. Photocleavage of the hairpin leads to the mRNA-mediated
toehold displacement of the redox-active strand associated with the
probe, leading to the depletion of the voltammetric response of the
probe. The parallel optical and electrochemical detection of the mRNA
at a single cell level is demonstrated
Engineering Biosensors with Dual Programmable Dynamic Ranges
Although extensively used in all
fields of chemistry, molecular recognition still suffers from a significant
limitation: hostâguest binding displays a fixed, hyperbolic
doseâresponse curve, which limits its usefulness in many applications.
Here we take advantage of the high programmability of DNA chemistry
and propose a universal strategy to engineer biorecognition-based
sensors with dual programmable dynamic ranges. Using DNA aptamers
as our model recognition element and electrochemistry as our readout
signal, we first designed a dual signaling âsignal-onâ
and âsignal-offâ adenosine triphosphate (ATP) sensor
composed of a ferrocene-labeled ATP aptamer in complex to a complementary,
electrode-bound, methylene-blue labeled DNA. Using this simple âdimericâ
sensor, we show that we can easily (1) tune the dynamic range of this
dual-signaling sensor through base mutations on the electrode-bound
DNA, (2) extend the dynamic range of this sensor by 2 orders of magnitude
by using a combination of electrode-bound strands with varying affinity
for the aptamers, (3) create an ultrasensitive dual signaling sensor
by employing a sequestration strategy in which a nonsignaling, high
affinity âdepletantâ DNA aptamer is added to the sensor
surface, and (4) engineer a sensor that simultaneously provides extended
and ultrasensitive readouts. These strategies, applicable to a wide
range of biosensors and chemical systems, should broaden the application
of molecular recognition in various fields of chemistry
Erythrocyte Membrane-Camouflaged Aggregation-Induced Emission Nanoparticles for Fetal Intestinal Maturation Assessment
Assessment of fetal maturity is essential for timely
termination
of pregnancy, especially in pregnant women with pregnancy complications.
However, there is a lack of methods to assess the maturity of fetal
intestinal function. Here, we constructed erythrocyte membrane-camouflaged
aggregation-induced emission (AIE) nanoparticles. Nanocore is formed
using a hollow mesoporous silicon nanobox (HMSN) of different particle
sizes loaded with AIE luminogens -PyTPA (P), which are then co-extruded
with erythrocyte membranes (M) to construct M@HMSN@P. The 100 nm M@HMSN@P
has a more effective cellular uptake efficiency in vitro and in vivo.
Swallowing and intestinal function in fetal mice mature with the increase
in gestational age. After intrauterine injection of M@HMSN@P, they
were swallowed and absorbed by fetal mice, and their swallowed and
absorbed amount was positively correlated with the gestational age
with a correlation coefficient of 0.9625. Using the M@HMSN@P (fluorescence
intensity) in fetal mice, the gestational age can be imputed, and
the difference between this imputed gestational age and the actual
gestational age is less than 1 day. Importantly, M@HMSN@P has no side
effect on the health status of pregnant and fetal mice, showing good
biocompatibility. In conclusion, we constructed M@HMSN@P nanoparticles
with different particle sizes and confirmed that the smaller size
M@HMSN@P has more efficient absorption efficiency and it can assess
fetal intestinal maturity by the intensity of the fluorescence signal
Lab in a Tube: Ultrasensitive Detection of MicroRNAs at the Single-Cell Level and in Breast Cancer Patients Using Quadratic Isothermal Amplification
Through
rational design of a functional molecular probe with high
sequence specificity that takes advantage of sensitive isothermal
amplification with simple operation, we developed a one-pot hairpin-mediated
quadratic enzymatic amplification strategy for microRNA (miRNA) detection.
Our method exhibits ultrahigh sensitivity toward miR-21 with detection
limits of 10 fM at 37 °C and 1 aM at 4 °C, which corresponds
to nine strands of miR-21 in a 15 ÎŒL sample, and it is capable
of distinguishing among miRNA family members. More importantly, the
proposed approach is also sensitive and selective when applied to
crude extractions from MCF-7 and PC3 cell lines and even patient tissues
from intraductal carcinoma and invasive ductal carcinoma of the breast
Assembly and Densification of Nanowire Arrays via Shrinkage
Chemically
synthesized semiconductor nanowires (NWs) have demonstrated
substantial promise for nanoelectronics, nanoenergy, and nanobiotechnology,
but the lack of an effective and controllable assembly process has
limited the wide adoption of NWs in these areas. Here we demonstrate
a facile, robust, and controllable approach to assembling and densifying
a parallel array of NWs using shrinkable shape memory polymers. Using
thermal-induced shrinkage of polystyrene, we were able to successfully
assemble and densify NW arrays up to close-packing and, furthermore,
achieve tunable density (up to âŒ300% amplification of density)
by controlling the shrinkage process. We also demonstrate scalable
assembly and densification of NWs on a 2.5 Ă 6 inch scale to
explore the manufacturability of the shrink-induced assembly process.
Finally, we demonstrate the successful transfer of the shrink-assembled
NW arrays onto various 2-dimensional and 3-dimensional substrates
without compromising the integrity of NW assembly and density
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