A simple method is proposed in this work for the detection of SARS-CoV-2 RNA based on primer exchange reaction (PER). By ingeniously integrating the PER cascade and CRISPR/cas12a system, this...
Long non-coding RNAs (lncRNAs) played vital roles in
physiological
and pathological conditions. Consistent results from cell experiments,
animal experiments, and clinical studies suggested that lncRNA HULC
was an oncogenic lncRNA serving as a potential diagnostic and prognostic
marker of hepatocellular carcinoma. In this study, we developed a
fluorescent biosensor for lncRNA HULC detection based on rolling circle
amplification (RCA) induced by multi-primer probes. Multiple primer
probes can not only combine with lncRNA to break its secondary structure,
which was conducive to lncRNA captured by Y-shaped probes, but also
trigger multiple RCA reactions to achieve signal amplification and
the goal of sensitive detection of lncRNA. Compared to previous detection
methods, in this scheme, we took advantage of the long sequence characteristics
of lncRNA to make it a carrier that can bind multiple primers to initiate
RCA. This newly designed biosensor provided a linear range from 1
pM to 100 nM with a detection limit of 0.06 pM. This method can provide
a new idea for the application of isothermal amplification in detecting
lncRNA. Furthermore, the application of the biosensor in liver cancer
cell lines and whole blood samples from hepatocellular carcinomatosis
patients also confirmed that the method had good selectivity and sensitivity
to lncRNA HULC. This method offered a new way for transforming specific
lncRNA into clinical application for diagnosis, prognosis, or predicting
treatment response.
Exosome-based liquid biopsy technologies play an increasingly prominent role in tumor diagnosis. However, the simple and sensitive method for counting exosomes still faces considerable challenges. In this work, the CD63 aptamer-modified DNA tetrahedrons on the gold electrode were used as recognition elements for the specific capture of exosomes. Partially complementary DNA probes act as bridges linking trapped exosomes and three AuNP−DNA signal probes. This clover-like structure can tackle the recognition and sensitivity issues arising from the undesired AuNP aggregation event. When cancerous exosomes are present in the system, the high accumulation of methylene blue molecules from DNA− AuNP nanocomposites on the surface of the electrode leads to an intense current signal. According to the results, the aptasensor responds to MCF-7 cell-derived exosomes in the concentration range from 1.0 × 10 3 to 1.0 × 10 8 particles•μL −1 , with the detection limit of 158 particles•μL −1 . Furthermore, the aptasensor has been extended to serum samples from breast cancer patients and exhibited excellent specificity. To sum it up, the aptasensor is sensitive, straightforward, less expensive, and fully capable of receiving widespread application in clinics for tumor monitoring.
Aptamer-based methods have attracted increasing interest
due to
flexible engineering, but their generality is limited by the heterogeneity
of signal transduction mechanisms. Given the fact that nonlinear and
large molecules are more likely to make the nanosurface overloaded,
we investigated a novel signal transduction process to extend the
application of aptasensors. In this work, an aptamer complementary
element (ACE) is designed with a primer region to serve as the signal
probe, which can fully hybridize with an aptamer and be separated
by magnetic beads (MBs). Upon target binding, the formed aptamer/target
complex is much larger than the linear aptamer/ACE-primer dimer, causing
overload of MBs on account of steric hindrance. An extra aptamer/ACE-primer
can escape from the surface to the supernatant, which can be amplified
by a catalytic hairpin assembly (CHA) circle. The size-dependent signal
transduction and the modular design endow the method with high generality
and flexibility for protein analysis. The proposed aptasensor was
successfully applied to the detection of tau proteins ranging from
0.5 to 1000 ng mL–1 with a limit of detection (LOD)
as low as 0.254 ng mL–1. The recovery tests in both
human serum and cerebra spinal fluid confirmed the high accuracy and
stability. Furthermore, a successful distinction was made between
AD patients and healthy controls by the method, suggesting the possible
applicability for practical analysis of tau proteins.
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