Binary detection of protein and nucleic acid enabled cancer diagnosis through branched hybridization chain reaction.

Developing isothermal bio-analyzers for amplified detection of multi-factor diseases like cancer biomarkers (nucleic acid and protein) has facilitated the early diagnosis and clinical theranostics. In light of that, a sensitive detection system was developed assisted by the recognition capability of a functional aptamer followed by cyclic self-assembly of three auxiliary hairpins via branched hybridization chain reaction (b-HCR) performance. In the downstream process, in the presence of hemin, split sequences of a DNAzyme brought in close proximity to facilitate the color alteration of the solution to a green appearance. By ingenious exerting multi-level amplification, the assay empowered sensitive detection of miR-21 and PDGF-BB related cancer biomarkers with LOD values of 10 pM and 40 nM, respectively. Taken together, simplicity, enzyme-free nature, excellent generality, affordable cost without any washing steps and immobilization makes the presented system a promising analytical tool in synthetic biology, designing nanomachines and point-of-care detection in resource-constrained settings.

Diabetes is associated with higher mortality and severity in hospitalized patients with COVID-19.

As a novel cause of pneumonia, coronavirus disease 2019 (COVID-19) has rapidly progressed worldwide. Previous studies have indicated COVID-19 patients with diabetes show higher mortality rates and more severe COVID-19 infection with an increased requirement for intensive care and hospital length of stay (LOS) compared to non-diabetic patients. The present study aimed to investigate the association of diabetes and COVID-19 outcome with severity of disease in hospitalized patients. The present case-control study included 268 patients diagnosed with COVID-19 who were hospitalized in Ayatollah Khoyi Hospital, Khoy, Iran. Diabetes was identified based on medical history and/or criteria of published documents. Out of 268 patients (median age of 59 years; 53.4 % male), 127 patients had diabetes (47 %). Diabetic patients had remarkably higher mortality rates (adjusted odds ratio, aOR: 3.36; confidence interval, CI: 1.17-9.66), requirement for invasive mechanical ventilation (IMV) (aOR: 4.59; CI: 1.38-15.25), and LOS (aOR: 1.13; CI: 1.06-1.24) compared to patients without diabetes. Inflammatory biomarkers including C-reactive protein (CRP), lactate dehydrogenase (LDH), and erythrocyte sedimentation rate (ESR) were increased in patients with diabetes compared to non-diabetic patients (P < 0.05 for all the comparisons). In hospitalized patients with COVID-19, diabetes was correlated with increased disease severity and mortality.

Colorimetric nanoplatform for visual determination of cancer cells via target-catalyzed hairpin assembly actuated aggregation of gold nanoparticles.

According to aptamer-mediated hairpin DNA cascade amplifier and gold nanoparticles aggregation, an optical platform for cancer cells determination has been proposed. High-affinity chimeric aptamers were used for cancer cell detection and also as an initiator for beginning hairpin assembly to construct three-way junction (3WJ) nanostructures. These three hairpins were modified at 3' ends with biotin. In the presence of target cell, chimeric aptamer binds to its ligand on cell surface and initiates 3WJ nanostructures formation. These 3WJ nanostructures interact with streptavidin-modified gold nanoparticles (AuNPs) via non-covalent biotin-streptavidin interactions and create a crossover lattice of nanoparticles. This event leads to AuNPs aggregation and red-shifting. The results were confirmed by gel electrophoresis and UV-visible spectrophotometry. The dynamic range of this assay is 25 to 107 cells with a detection limit of 10 cells which is respectively 9 and 4 times more significant than the sensitivity of AuNP-based approaches without amplification and enzyme-mediated signal amplification. Graphical abstract.

Colorimetric detection of miRNA-21 by DNAzyme-coupled branched DNA constructs.

Fluctuation of nucleic acid expression and ultrasensitive and specific detection of these variations in expression is a crucial subject in molecular medicine and clinical theranostics. A novel DNAzyme-coupled branched hybridization chain reaction (b-HCR) assay is reported for efficient signal-amplified detection of miRNA in this study. This assay was composed of a translator (T) hybridized with miR-21 to initiate the first HCR by hairpin 1 (H1) and hairpin 2 (H2). The primary HCR provided a backbone chain for numerous branches budding through hairpin 3 (H3) and hairpin 4 (H4) assembles. In the presence of hemin, the G-rich domains embedded in H1 and H4 produce an active G-quadruplex DNAzyme upon exposure to a target that could catalyze the oxidation of colorless substrate to colored product. The present approach has the potential to be used for quantitative detection of miR-21 with a sensitivity and a dynamic range of 1 pM and 1 pM to 1 nM, respectively.

Target-triggered three-way junction in conjugation with catalytic concatemers-functionalized nanocomposites provides a highly sensitive colorimetric method for miR-21 detection.

With the great advances in DNA nanotechnology, scientists have shown interest in developing dynamic nanostructures for theranostic applications, analyte sensing and cargo delivery. Here, we present a specific enzyme-free ultrasensitive platform based on a multilayer coupled signal amplification strategy to quantify miR-21 molecule. The biosensor was integrated based on three signal amplification gadgets, namely a translator-mediated catalytic hairpin assembly (CHA), a multilayer DNA concatemer on the surface of gold decorated magnetic nanoparticle (GMNP), and a DNAzyme-mediated catalytic signal amplification. MiR-21 mediates the release of a DNA translator from an immobilized duplex to engage in a CHA reaction using three hairpins, including a GMNP-conjugated hairpin 1 (H1), biotin-labeled hairpin 2 (H2) and a GMNP-conjugated hairpin 3 (H3) to form a three-way junction (3WJ). Meanwhile, a plenty of initiator strand 0 (S0) on GMNPs - each of which has been bifunctionalized with S0/H1 or S0/H3 - drive several multilayer peroxidase-mimicking DNAzyme concatemers in the presence of two accessory oligonucleotides; strand 1 (S1) and strand 2 (S2). Since a G-rich sequence was attached at the 5'-end of S1 strand, in the presence of hemin cofactor, an active G-quadruplex DNAzyme with peroxidase activity was formed. The concatemers on the surface of GMNPs can convert a colorless substrate to a green product. The biosensor can detect as low as 1 aM of miR-21 and provide an excellent capability to discriminate single-base mismatches. The required time for the formulation of the assay reagents is about three days and the reaction time for the detection of miR-21 takes place in less than four hours.

Aptamer-integrated DNA nanoassembly: A simple and sensitive DNA framework to detect cancer cells.

The development of powerful techniques to detect cancer cells at early stages plays a notable role in diagnosing and prognosing cancer patients and reducing mortality. This paper reports on a novel functional DNA nanoassembly capable of detecting cancer cells based on structural DNA nanotechnology. DNA nanoassemblies were constructed by the self-assembly of a DNA concatemer to a plenty of sticky-ended three-way junctions. While an aptamer moiety guided the nanoassembly to the target cancer cell, the peroxidase-mimicking DNAzymes embedded in the nanoassemblies were used as the sensing element to produce colorimetric signals. As proof-of-concept, as low as 175 cancer cells were detected by the assay, and color change was clearly distinguished by the naked eyes. The proposed system enjoys potential applications for point-of-care cancer diagnosis, with its excellent sensitivity and selectivity.