A novel ß-cyclodextrin-assisted enhancement strategy for portable and sensitive detection of miR-21 in human serum.

Benefiting from our discovery that ß-cyclodextrin (ß-CD) could enhance the catalytic activity of invertase through hydrogen bonding to improve detection sensitivity, a highly sensitive and convenient biosensor for the detection of miR-21 was proposed, which is based on the simplicity of reading signals from a personal glucose meter (PGM), combined with self-assembled signal amplification probes and the performance of ß-CD as an enhancer. In the presence of miR-21, magnetic nanoparticle coupled capture DNA (MNPs-cDNA) could capture it and then connect assist DNA/H1-invertase (aDNA/H1) and self-assembled signal amplification probes (H1/H2) in turn. As a result, a "super sandwich" structure was formed. The invertase on MNPs-cDNA could catalyze the hydrolysis of sucrose to glucose and this catalytic process could be enhanced by ß-CD. The PGM signal exhibited a linear correlation with miR-21 concentration within the range of 25 pmol L-1 to 3 nmol L-1, and the detection limit was as low as 5 pmol L-1 with high specificity. Moreover, the recoveries were 103.82-124.65% and RSD was 2.59-6.43%. Furthermore, the biosensor was validated for the detection of miR-21 in serum, and the results showed that miR-21 levels in serum samples from patients with Diffuse Large B-Cell Lymphoma (DLBCL) (n = 12) were significantly higher than those from healthy controls (n = 12) (P < 0.001). Therefore, the ingenious combination of PGM-based signal reading, self-assembled signal amplification probes and ß-CD as an enhancer successfully constructed a convenient, sensitive and specific biosensing method, which is expected to be applied to clinical diagnosis.

Endocytosis and intracellular RNAs imaging of nanomaterials-based fluorescence probes.

Recently, using nanomaterials to enhance the endocytosis capability and sensitivity of probes for RNA imaging in living cells has gotten the attention of many researchers. Nanomaterials, as a reliable alternative to transfection reagents, could prevent nucleic acid probes from being degraded by DNase, and bring them into sub-cellular locations for efficient internalization. Therefore, nanomaterial-based fluorescent probes (NFPs) provide a promising sensing platform to realize in situ RNA detection and imaging, which can reveal the expression of RNA at single cell level and provide large amount of information about RNA spatial localization. Meanwhile, many RNAs are in low abundance in living cells, resulting in difficulty in sensitive detection. Thus, the incorporation of NFPs and signal amplification strategy offers a broader prospect for the detection of RNAs, that have been proven as predominant therapeutic targets or diagnostic biomarkers. Herein, the purpose of our review is to first introduce the general procedure of NFPs used for in situ RNA imaging and how nanomaterials deliver these probes into living cells. Further, we focused on different kinds of nanomaterials that are mainly used for sensitive detection of RNAs and those in low abundance, through different signal read-out modes.

Construction and bioapplications of aptamer-based dual recognition strategy.

Aptamer-based dual recognition strategy, using dual aptamers or the cooperation of aptamers with other recognition elements, can better utilize the advantages of each recognition molecule and increase the design flexibility to effectively overcome the limitations of a single molecule recognition strategy, thereby improving the sensitivity and selectivity and facilitating the regulation of biological process. Hence, this review systematically tracks the construction and application of dual aptamers recognition strategy in the versatile detection of protein biomarkers, pathogenic microorganisms, cancer cells, and the treatment of some diseases and, more importantly, in functional regulation and imaging of cell-surface protein receptors. Then, the cooperation of aptamers with other recognition elements are briefly introduced. Potential challenges facing this field have been highlighted, aiming to expand bioanalytical applications of aptamer-based dual or multiple recognition strategies and meet the growing demand for precision medicine.

Revealing the metabolic mechanism of dandelion extract against A549 cells using UPLC-QTOF MS.

Dandelion extract exhibits potential anticancer activity and is expected to be a new type of natural anticancer drug. However, the effect mechanism of dandelion extract to lung cancer cells is still unclear. Here, untargeted metabolomics approach based on LC-MS was used to characterize the metabolic responses of A549 cells to dandelion extract exposure and to provide new clues for the antitumor mechanism of dandelion extract from the metabolomics perspective. A total of 16 differentially expressed and time-related metabolites were identified between dandelion extract exposure and control groups. The perturbed metabolic pathways of A549 cells after dandelion extract exposure mainly include the glycerophospholipid metabolism and purine metabolism. These results concluded that dandelion extract may exert anticancer activity by affecting malignant proliferation, disturbing the stability of cell membrane structure, reducing the adhesion of tumor cells to extracellular matrix and fibronectin, and finally inducing tumor cell death.

A simple "signal off-on" fluorescence nanoplatform for the label-free quantification of exosome-derived microRNA-21 in lung cancer plasma.

A simple nanoplatform based on molybdenum disulfide (MoS2) nanosheets, a fluorescence quencher (signal off), and a hybridization chain reaction (HCR) signal amplification (signal on) used for the enzyme-free, label-free, and low-background signal quantification of microRNA-21 in plasma exosome is reported. According to the sequence of microRNA-21, carboxy-fluorescein (FAM)-labeled hybridization probe 1 (FAM-H1) and hybridization probes 2 (FAM-H2) were designed with excitation maxima at 488 nm and emission maxima at 518 nm. MoS2 nanosheets could adsorb FAM-H1 and FAM-H2 and quenched their fluorescence signals to reduce the background signal. However, HCR was triggered when microRNA-21 was present. Consequently, HCR products containing a large number of FAM fluorophores can emit a strong fluorescence at 518 nm and could realize the detection of microRNA-21 as low as 6 pmol/L and had a wide linear relation of 0.01-25 nmol/L. This assay has the ability of single-base mismatch recognition and could identify microRNA-21 with high specificity. Most importantly, this approach was successfully applied to the detection of plasma exosomal microRNA-21 in patients with lung cancer, and it is proposed that other targets can also be detected by changing the FAM-H1 and FAM-H2 corresponding to the target sequence. Thus, a novel, hands-on strategy for liquid biopsy was proposed and has a potential application value in the early diagnosis of lung cancer.

Metabolomic analysis of plasma from normal-weight adults with hypo-HDL cholesterolemia by UPLC-QTOF MS.

High-density lipoprotein cholesterol (HDL-C) is negatively correlated with atherosclerotic cardiovascular disease. The prevalence of hypo-HDL cholesterolemia is as high as 33.9%. The plasma metabolomic differences between hypo-HDL cholesterolemia populations and normal controls were investigated using ultra-high-performance liquid chromatography-quadrupole time-of-flight mass spectrometry. Participants with hypo-HDL cholesterolemia and normal controls were clearly discriminated from each other on the orthogonal partial least squares-discriminant analysis score plot and a total of 90 differential metabolites were identified, including down-regulated phosphatidylserine [18:0/20:3(8Z,11Z,14Z)], phosphatidylcholine [19:0/18:3(6Z,9Z,12Z)], phosphatidylserine, phosphatidylethanolamine [18:0/20:4(5Z,8Z,11Z,13E) (15Ke)], etc., and up-regulated triglyceride [15:0/18:1(9Z)/18:3(9Z,12Z,15Z)][iso6], 13-methyl-1-tritriacontene, tridodecylamine, etc. Most of the changed metabolites were lipids, notably, a significant part of which were odd chain fatty acid incorporated lipids. Carnitine shuttle was the most significant metabolic pathway, except for the disturbed glycerophospholipid metabolism, glycosphingolipid metabolism and sphingolipid metabolism in participants with hypo-HDL cholesterolemia. We identified the key metabolites and metabolic pathways that may be changed in hypo-HDL cholesterolemia participants, providing useful clues for studying the metabolic mechanisms and for early prevention of hypo-HDL cholesterolemia and dyslipidemia.