6 research outputs found
Simple and Sensitive Quantification of MicroRNAs via PS@Au Microspheres-Based DNA Probes and DSN-Assisted Signal Amplification Platform
Identifying the microRNA
(miRNA) expression level can provide critical information for early
diagnosis of cancers or monitoring the cancer therapeutic efficacy.
This paper focused on a kind of gold-nanoparticle-coated polystyrene
microbeads (PS@Au microspheres)-based DNA probe as miRNA capture and
duplex-specific nuclease (DSN) signal amplification platform based
on an RGB value readout for detection of miRNAs. In virtue of the
outstanding selectivity and simple experimental operation, 5′-fluorochrome-labeled
molecular beacons (MBs) were immobilized on PS@Au microspheres via
their 3′-thiol, in the wake of the fluorescence quenching by
nanoparticle surface energy transfer (NSET). Target miRNAs were captured
by the PS@Au microspheres-based DNA probe through DNA/RNA hybridization.
DSN enzyme subsequently selectively cleaved the DNA to recycle the
target miRNA and release of fluorophores, thereby triggering the signal
amplification with more free fluorophores. The RGB value measurement
enabled a detection limit of 50 fM, almost 4 orders of magnitude lower
than PS@Au microspheres-based DNA probe detection without DSN. Meanwhile,
by different encoding of dyes, miRNA-21 and miRNA-10b were simultaneously
detected in the same sample. Considering the ability for quantitation,
high sensitivity, and convenient merits, the PS@Au microspheres-based
DNA probe and DSN signal amplification platform supplied valuable
information for early diagnosis of cancers
Effective Bioactivity Retention of Low-Concentration Antibodies on HFBI-Modified Fluorescence ICTS for Sensitive and Rapid Detection of PSA
Nowadays, increasing
analytical sensitivity is still a big challenge
in constructing membrane-based fluorescence immunochromatography test
strips (FICTS). However, the bioactivity of antibody (Ab) immobilized
on the test line (T line) of porous nitrocellulose membrane (PNM),
which directly influences the analytical sensitivity, is less studied.
In this work, a novel amphiphilic hydrophobin (HFBI) protein was introduced
to modify the T line to effectively retain the Abs’ bioactivity.
The results indicated that HFBI could self-assemble on the PNM and
immobilize the Abs in the “stand-up” orientation. Compared
with the conventional FICTS, the HFBI-modified FICTS with only 0.2
mg/mL of monoclonal Abs on T line enable more accurate quantitative
detection and better sensitivity (0.06 ng/mL for prostate specific
antigen), which is more than 2 orders of magnitude lower than that
of the conventional FICTS with the same concentration of monoclonal
Abs on T line. Furthermore, the accuracy of this HFBI-modified FICTS
was investigated by testing 150 clinical serum samples and the detection
results were coincident with those by electrochemiluminescence immunoassay.
Our results provide a novel and promising strategy of Ab immobilization
on FICTS for near-patient and point-of-care application
Enhanced Fluorescence ELISA Based on HAT Triggering Fluorescence “Turn-on” with Enzyme–Antibody Dual Labeled AuNP Probes for Ultrasensitive Detection of AFP and HBsAg
At present, enzyme-linked immunosorbent
assay (ELISA) is considered to be the most appropriate approach in
clinical biomarker detection, with good specificity, low cost, and
straightforward readout. However, unsatisfactory sensitivity severely
hampers its wide application in clinical diagnosis. Herein, we designed
a new kind of enhanced fluorescence enzyme-linked immunosorbent assay
(FELISA) based on the human alpha-thrombin (HAT) triggering fluorescence
“turn-on” signals. In this system, detection antibodies
(Ab<sub>2</sub>) and HAT were labeled on the gold nanoparticles (AuNPs)
to form the detection probes, and a bisamide derivative of Rhodamine<sub>110</sub> with fluorescence quenched served as the substrate of HAT.
After the sandwich immunoreaction, HAT on the sandwich structure could
catalyze the cleavage of the fluorescence-quenched substrate, leading
to a strong fluorescence signal for sensing ultralow levels of alpha
fetoprotein (AFP) and hepatitis B virus surface antigen (HBsAg). Under
the optimized reaction conditions, AFP and HBsAg were detected at
the ultralow concentrations of 10<sup>–8</sup> ng mL<sup>–1</sup> and 5 × 10<sup>–4</sup> IU mL<sup>–1</sup>, respectively,
which were at least 10<sup>4</sup> times lower than those of the conventional
fluorescence assay and 10<sup>6</sup> times lower than those of the
conventional ELISA. In addition, we further discussed the efficiency
of the sensitive FELISA in clinical serum samples, showing great potential
in practical applications