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A simple and rapid method has been developed to detect the nucleic acid–based polycyclic aromatic hydrocarbons as a probe by the amplified resonance light scattering signals of DNA hybridization. Five polycyclic aromatic hydrocarbons including naphthalene, pyrene, fluoranthene, anthracene, and phenanthrene, particularly naphthalene, with double-stranded DNA and single-stranded DNA in aqueous solution were investigated. Through amplified resonance light scattering signals, the complementary and mismatched sequences of DNA can be both detected and identified easily. Mechanism investigations by multiple spectra have shown that groove binding occurs between PAHs and double-stranded DNA. Supplemental materials are available for this article. Go to the publisher's online edition ofSpectroscopy Lettersto view the supplemental file. [ABSTRACT FROM AUTHOR]

Abstract: The design and fabrication of novel filter is a promising approach to realize the reduction of harmful substance in mainstream cigarette smoke. In our work, a kind of pyrene (PYR) imprinted polymer as a part of improved filter has been successfully synthesized for the determination of polycyclic aromatic hydrocarbons (PAHs) in mainstream cigarette smoke. The molecularly imprinted polymers (MIPs) showed an good affinity towards PYR with binding capacity (Q max) of 18.33mg/g. Accordingly, the MIPs were used as a solid phase extraction (SPE) sorbent for the extraction and enrichment of PAHs in mixed samples to evaluate the selectivity about the MIPs. When the cellulose acetate (CA)-filter was replaced by a MIPs-filter, the amount of PAHs in the mainstream smoke was reduced by 63.6%. The application will provide technical support for the design of functional filters to reduce the harms brought by cigarette suction. [Copyright &y& Elsevier]

Molecular imprinted polymer (MIP) was prepared through thermal polymerization by using artemisinin as the template molecule, styrene as the functional monomer, ethylene glycol dimethacrylate (EGDMA) as the cross-linker, and azobisisobutyronitrile (AIBN) as the initiator. Evaluated by static, kinetic, and bonding capacity adsorption tests, the polymer exhibited a special selective rebinding to artemisinin. Scatchard analysis revealed that two different binding sites were formed in the polymers. The novel imprinted polymer was used as a solid-phase extraction (SPE) sorbent for the extraction of artemisinin fromArtemisia annua L., followed by HPLC-UV analysis. The maximum static adsorption capacity of the artemisinin-imprinted sorbent for artemisinin was 8.46 mg g−1.The application of artemisinin-imprinted polymers with high affinity and excellent selectivity toward artemisinin in SPE might offer a novel method for the enrichment and determination of the active ingredient in Chinese medicine. [ABSTRACT FROM PUBLISHER]

Abstract: A new assay is developed for direct detection of DNA hybridization using triphenylmethane dye as a probe. It is based on various spectroscopic methods including resonance light scattering (RLS), circular dichroism (CD), ultraviolet spectra and fluorescence spectra, as well as atomic force microscopy (AFM), six triphenylmethane dyes interact with double strand DNA (dsDNA) and single strand DNA (ssDNA) were investigated, respectively. The interaction results in amplified resonance light scattering signals and enables the detection of hybridization without the need for labeling DNA. Mechanism investigations have shown that groove binding occurs between dsDNA and these triphenylmethane dyes, which depends on G–C sequences of dsDNA and the molecular volumes of triphenylmethane dyes. Our present approaches display the advantages of simple and fast, accurate and reliable, and the artificial samples were determined with satisfactory results. [Copyright &y& Elsevier]

We are presenting new and highly sensitive hybridization assays. They are based on various spectroscopic methods including resonance light scattering, circular dichroism, ultraviolet spectra and fluorescence spectra, as well as atomic force microscopy, and relies on the interaction of the Cu(II), Ni(II), Mg(II), Co(II), Cd(II), and Zn(II) complexes, respectively, of tetraphenylporphyrin (TPP) with double-strand DNA (dsDNA) and single strand DNA (ssDNA). The interaction results in amplified resonance light scattering (RLS) signals and enables the detection of hybridization without the need for labeling DNA. The RLS signals are strongest in case of the Cu (II)-TPP complex which therefore was selected as the probe. The technique is simple, robust, accurate, and can be completed in less than one hour. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

Abstract: Interactions of the anti-inflammatory drug ketoprofen with calf thymus DNA (ctDNA) in aqueous solution have been studied by multi-spectroscopic method including resonance light scattering (RLS) technique, ultraviolet spectra (UV), 1H NMR, etc. The characteristics of RLS spectra, the effective factors and optimum conditions of the reaction have been unequivocally investigated. Mechanism investigations have shown that ketoprofen can bind to ctDNA by groove binding and form large particles, which resulted in the enhancement of RLS intensity. In Critic acid-Na2HPO4 buffer (pH=6.5), ketoprofen has a maximum peak 451.5nm and the RLS intensity is remarkably enhanced by trace amount of ctDNA due to the interaction between ketoprofen and ctDNA. The enhancement of RLS signal is directly proportional to the concentration of ctDNA in the range of 1.20×10−6–1.0×10−5 mol/L, and its detection limit (3σ) is 1.33×10−9 mol/L. The method is simple, rapid, practical and relatively free from interference generated by coexisting substance, and was applied to the determination of trace amounts of nucleic acid in synthetic samples with satisfactory results. [Copyright &y& Elsevier]

Abstract: A new process has been developed to separate ketoconazole (KTZ) enantiomers by membrane extraction, with the oppositely preferential recognition of hydrophobic and hydrophilic chiral selectors in organic and aqueous phases, respectively. This system is established by adding hydrophobic l-isopentyl tartrate (l-IPT) in organic strip phase (shell side) and hydrophilic sulfobutylether-β-cyclodextrin (SBE-β-CD) in aqueous feed phase (lumen side), which preferentially recognizes (+)-2R,4S-ketoconazole and (−)-2S,4R-ketoconazole, respectively. The studies performed involve two enantioselective extractions in a biphasic system, where KTZ enantiomers form four complexes with SBE-β-CD in aqueous phase and l-IPT in organic phase, respectively. The membrane is permeable to the KTZ enantiomers but non-permeable to the chiral selector molecules. Fractional chiral extraction theory, mass transfer performance of hollow fiber membrane, enantioselectivity and some experimental conditions are investigated to optimize the separation system. Mathematical model of I/II=0.893e 0.039NTU for racemic KTZ separation by hollow fiber extraction, is established. The optical purity for KTZ enantiomers is up to 90% when 9 hollow fiber membrane modules of 30cm in length in series are used. [Copyright &y& Elsevier]

Abstract: A new high-sensitivity detection of protein assay at the nanogram level is proposed based on multi-spectroscopic methods including resonance light scattering (RLS), atomic force microscopy (AFM), ultraviolet spectra (UV) and fluorescence spectra etc. Under the optimum conditions, the amplified RLS signals of anionic azo dyes Eriochrome Red B (ERB) in the presence of anionic surfactant sodium dodecyl sulphonate (SDS) was in proportion to the concentration of proteins in the range of 0.0–3.5mgL−1 and 3.5–12.5mgL−1 for bovine serum albumin (BSA), 0.0–2.0mgL−1 and 2.0–8.0mgL−1 for human serum albumin (HSA). The detection limits were 4.2ngmL−1 and 2.7ngmL−1, respectively. The method was satisfactorily applied to the measurement of total protein in human serum samples and a high-sensitivity was achieved. [ABSTRACT FROM AUTHOR]

Abstract: Multi-spectroscopic methods including resonance light scattering (RLS), ultraviolet spectra (UV), fluorescence spectra, 1H NMR spectroscopy, coupled with thermo-denaturation experiments were firstly used to study the interaction of antitumor drug tamoxifen (TMX) with calf thymus (ctDNA) in acetate buffer solutions (pH 4.55). The interaction of TMX with ctDNA could cause a significant enhancement of RLS intensity, the hyperchromic effect, red shift of absorption spectra and the fluorescence quenching of TMX, indicating that there is an inserting interaction between TMX and ctDNA. This inference was confirmed by 1H NMR spectroscopy. The chemical shift of the benzene proton changes significantly which indicates that TMX could insert into the base pairs of ctDNA. These studies are valuable for a better understanding the mode of TMX–ctDNA interaction further, which are important and useful for designing of new ctDNA targeted drug. And the antitumor drug TMX inserted directly into ctDNA in vitro, which can provide a lot of useful information to explore the development of new and highly effective anti-cancer drugs. [Copyright &y& Elsevier]

Abstract: A new high-sensitivity detection of protein assay at the nanogram level is developed based on the amplified resonance light scattering signals (RLS) of Tichromine (TCM). In Walpole (NaAc–HCl) buffer (pH 4.05), TCM reacts with proteins to form large particles, which results in remarkable enhanced RLS signals characterized by three peaks at 293nm, 399nm and 553nm. Mechanistic studies showed that the enhanced RLS stems from a large complex of TCM–BSA formed for the electrostatic effect between TCM and BSA. With the enhanced RLS signals at the three wavelengths, the enhanced RLS intensity is proportional to the concentration of proteins in an appropriate range. The lowest limit of determination was 7.4ngmL−1. The proposed method was successfully applied to determine total protein in human serum samples. [Copyright &y& Elsevier]

Abstract: Methotrexate (MTX) as an antifolate, which is widely used as chemotherapeutic drugs. A high-dose MTX therapy has a direct toxicity influence on the non-germinal cells, especially the liver cells. It is known that the inject dose for adults is 10–30mg and is half for children for routine use, while our experiments showed that the optimum dosage of MTX which enhanced the RLS intensities to the maximum is 4.54ngml−1. The interaction of methotrexate (MTX) with nucleic acids in aqueous solution in the presence of cetyltrimethylammonium bromide (CTMAB), a kind of cationic surfactant similar to the Human cells, were investigated based on the measurements of resonance light scattering (RLS), UV–vis, fluorescence and NMR spectra, etc. The interaction has been proved to give a ternary complex of MTX–CTMAB–DNA in BR buffer (pH 9.30), which exhibits strong enhanced RLS signals at 339.5nm. [Copyright &y& Elsevier]

Abstract: The interaction of Acid chrome blue K (ACBK) with nucleic acids in weak basic medium was studied in the presence of cetyltrimethylammonium bromide (CTMAB) based on the measurements of resonance light scattering (RLS), UV–vis, NMR spectra, etc. In hexamethylene tetramine (HMTA) buffer (pH 7.45), ACBK and nucleic acids react with CTMAB to form a ternary complex, which results in strong enhanced RLS signals characterized by four peaks at 285, 335, 405.5 and 548nm. Mechanistic studies show that the enhanced RLS stems from the aggregation of ACBK on nucleic acids through the bridged and synergistic effect of CTMAB. With the enhanced RLS signals at the best wavelength at 335nm, the enhanced RLS intensity is proportional to the concentration of nucleic acids in a wide range. The lowest limit of determination was 7.52ngml−1, three synthetic samples were analyzed satisfactorily. And the combined points of the anionic dye ACBK with nucleic acids–CTMAB have been tentatively confirmed through the measurement of 1H NMR spectra. [Copyright &y& Elsevier]

Abstract: The interaction of xylenol orange (XO) and nucleic acids in the presence of cetyltrimethylammonium bromide (CTMAB) in aqueous solution has been studied by a resonance light-scattering (RLS) technique with a common spectrofluorometer. In hexamethylenetetramine (HMTA) buffer (pH7.30), XO and nucleic acids react with cetyltrimethylammonium bromide to form large particles of three-component complex, which results in strong enhanced RLS signals characterized by three peaks at 295.9, 335.5 and 542nm, Mechanistic studies showed that the enhanced RLS stems from the aggregation of XO on DNA through the bridged and synergistic effect of CTMAB. With the enhanced RLS signals at the three wavelengths, the enhanced RLS intensity is proportional to the concentration of nucleic acids in an appropriate range. The lowest limit of determination was 5.31ngml−1, three synthetic samples of yDNA were analyzed satisfactorily. [Copyright &y& Elsevier]

Abstract: An assay of deoxyribonucleic acids (DNA) determination, with the sensitivity at nanogram level, was established in the present study by using a common spectrofluorometer to detect the intensity of resonance light scattering (RLS). In hexamethylene tetramine (HMTA) buffer (pH 11.00), Bromocresol Green (BCG) and deoxyribonucleic acids (DNA) react with cetyltrimethylammonium bromide (CTMAB) to form large particles of three-component complex, which results in strong enhanced RLS signals characterized by three peaks at 336, 390, and 622nm and at 336nm that is the strongest of the three enhanced RLS peaks. Mechanistic studies showed that the enhanced RLS stems from the aggregation of BCG on DNA through the bridged and synergistic effect of CTMAB. Yeast DNA (yDNA), in the range of 0.05–0.90ngml−1, fish sperm DNA (fsDNA) in the range of 0.05–0.80ngml−1, and calf thymus DNA (ctDNA) in the range of 0.05–0.80ngml−1 can be determined if 2.0 × 10−6 moll−1 BCG was employed. The determination limit of yDNA was 12.7ngml−1. Three synthetic samples of yDNA were analyzed with good reproducibility. [Copyright &y& Elsevier]

Covalent organic frameworks (COFs) have attracted extensive attention as promising materials for the elimination of various organic pollutants due to their high surface area, inherent porosity and tailorable functionality. However, powdery COFs are difficult to separate and reuse, which greatly limits their practical applications. Herein, a β-cyclodextrin functionalized imine COF (β-CD-COF) aerogel with good crystallinity and chemical stability was synthesized by the Schiff base reaction using a one-pot method for efficient removal of anionic and cationic dyes from water. The prepared β-CD-COF aerogel has a macroscopic three-dimensional bulk and hierarchical porous structure, which is conducive to adsorption and recovery, and it not only showed high adsorption capacity and fast binding kinetics for single anionic and cationic dyes (3403.91 mg g−1 for methyl orange (MO) and 2199.37 mg g−1 for methylene blue (MB)), but also exhibited outstanding simultaneous adsorption capacity in different binary and ternary pollutant systems. Additionally, the β-CD-COF aerogel showed good reusability for the co-adsorption of MO and MB. These results demonstrate the great potential of β-CD-COF aerogels for the simultaneous removal of anionic and cationic dyes in environmental applications. [ABSTRACT FROM AUTHOR]

A dioxygen‐triggered selectively difunctionalization of olefins to achieve β‐hydroxysulfones has been developed. Particularly, the mechanism of this reaction can be controlled by DABCO, which act as a single electron transfer reagent, to selectively obtain ketosulfone or hydroxysulfone. The reaction was conducted in a clean, safe, mild, and catalyst‐free conditions. Moreover, as a proof‐of‐concept, two bioactive molecules were synthesized easily using this method. [ABSTRACT FROM AUTHOR]

Background Methods Results Conclusions TUB‐like protein 4 (TULP4) is one of the distant members of tubby family proteins, whose function remains largely unknown. In the present study, we intend to identify the role of TULP4 in schizophrenia from human samples and animal models.Whole‐exome sequencing was used to detect the four schizophrenia families collected. In different cell lines, the effects of identified variants in TULP4 gene on its expression and localization were analyzed. Knockdown models in utero and adult mice were employed to investigate the role of Tulp4 on neuronal migration and schizophrenia‐related behavior. Subsequently, co‐IP assays were used to search for proteins that interact with TULP4 and the effects of mutants on the molecular function of TULP4.For the first time, we identified five rare variants in TULP4 from schizophrenia families, of which three significantly reduced TULP4 protein expression. Knockdown the expression of Tulp4 delayed neuronal migration during embryological development and consequently triggered abnormal behaviors in adult mice, including impaired sensorimotor gating and cognitive dysfunction. Furthermore, we confirmed that TULP4 is involved in the formation of a novel E3 ligase through interaction with CUL5‐ELOB/C‐RNF7 and the three deleterious variants affected the binding amount of TULP4 and CUL5 to a certain extent.Together, we believe TULP4 plays an important role in neurodevelopment and subsequent schizophrenic‐related phenotypes through its E3 ubiquitin ligase function. [ABSTRACT FROM AUTHOR]

The catalytic hairpin-rigidified Y-shaped DNA through layer-by-layer assembly has been fixed on the surface of copper sulfide nanoparticles for the detection of survivin mRNA. The distance between the CHA probes fixed on the Y-shaped DNA is significantly shortened. The results show that the fluorescence of this nanomachine reached the maximum value in 50 min (excitation wavelength at 488 nm and emission wavelength 526 nm), and its reaction rate is more than 5-fold faster than that of the free-CHA control system. In addition, the nanomachine showed high sensitivity (LOD of 3.5 pM) and high specificity for the survivin mRNA detection. Given its fast response time and excellent detection performance, we envision that the catalytic hairpin-rigidified Y-shaped DNA-functionalized nanomachine will offer potential applications in disease diagnostics and clinical applications. [ABSTRACT FROM AUTHOR]

Evidence has shown that the gut microbiota is closely related to the pathogenesis of schizophrenia, but temporal changes in the gut microbiota of patients with schizophrenia (SZ) during treatment remain unclear. Here, to evaluate temporal changes in the gut microbiota in schizophrenia, we performed whole-genome shotgun metagenomics on fecal samples from 36 healthy controls (HCs) and 19 baseline-period patients, and followed up with patients upon treatment. Compared to that in HCs, beta diversity in SZ was significantly distinct. The genera Bacteroides, Prevotella and Clostridium were the top 3 altered genera between SZ and HCs, and the Bacteroides-Prevotella ratio was significantly increased in SZ. Thirty-three percent of differentially abundant species were short-chain fatty acid (SCFA)-producing bacteria. Functional analysis showed that glucose and lipid metabolism of the gut microbiota was decreased in SZ compared with those in HCs. The abundances of two rate-limiting enzymes in glucose and lipid metabolism, phosphofructokinase (PFK) and acetyl-CoA carboxylase (ACC), were significantly decreased in SZ, and differentially abundant metabolism-related enzymes were significantly associated with SCFA-producing bacteria. Next, we found that the abundance of SCFA-producing bacteria also changed after treatment and that Clostridium was significantly negatively correlated with the total positive and negative syndrome scale (PANSS) score in patients. Functional analysis showed that glycoside hydrolase family 30 incrementally increased in abundance during treatment and were significantly associated with SCFA-producing bacteria. Our findings help to provide evidence for the role of gut microbiota in the occurrence and development of schizophrenia. [ABSTRACT FROM AUTHOR]

As biomarkers of many diseases, glycoproteins are of great significance to clinical diagnostics. However, the determination of low abundant glycoproteins in complex biological samples without any pretreatment process is still a problem. In this study, a rapid and convenient separation method for highly efficient enrichment of glycoproteins is reported, based on pH double-responsive imprinted magnetic microspheres. Thin imprinted polymer shells were fabricated onto the surface of magnetic microspheres by free radical polymerization, using 2-(Dimethylamino) ethyl methacrylate as pH-sensitive monomer, 4-vinylphenylbronic acid as boronate affinity monomer, and ovalbumin (OVA) as template molecule. Combining the advantages of pH-sensitive monomer and boronate affinity monomer, rapidly capture-release of OVA could be modulated by changing solution pH. Moreover, high absorption ability (81.2 mg/g) was achieved within about 10 min. This study provided responsible way to imprint glycoproteins and showed great potential for glycoprotein detection in clinical diagnostic. [ABSTRACT FROM AUTHOR]

The surface imprinting technique has been developed to overcome the mass-transfer difficulty, but the utilization ratio of template molecules in the imprinting procedure still remains a challengeable task to be improved. In this work, specifically designed surface-imprinted microspheres were prepared by a template-oriented method for enantioseparation of amlodipine besylate. Submicron mesoporous silica microspheres were surface-modified with double bonds, followed by polymerizing methacrylic acid to generate carboxyl modified mesoporous silica microspheres (PMAA@SiO2). Afterwards, PMAA@SiO2 was densely adsorbed with ( S)-amlodipine molecules to immobilize template molecules through multiple hydrogen bonding interactions. Then surface molecular imprinting was carried out by cross-linking the carboxyl group of PMAA@SiO2 with ethylene glycol diglycidyl ether. The surface-imprinted microspheres showed fast binding kinetics of only 20 min for equilibrium adsorption, and the saturation adsorption capacity reached 137 mg/g. The imprinted materials displayed appreciable chiral separation ability when used as column chromatography for enantioseparation of amlodipine from amlodipine besylate, and the enantiomeric excess of ( S)-amlodipine reached 13.8% with only 2.3 cm column length by no extra chiral additives. Besides, the imprinted materials exhibited excellent reusability, and this allows the potential application for amplification production of amlodipine enantiomer. [ABSTRACT FROM AUTHOR]

Psychiatric disorders are a class of complex disorders characterized by brain dysfunction with varying degrees of impairment in cognition, emotion, consciousness and behavior, which has become a serious public health issue. The NGFR gene encodes the p75 neurotrophin receptor, which regulates neuronal growth, survival and plasticity, and was reported to be associated with depression, schizophrenia and antidepressant efficacy in human patient and animal studies. In this study, we investigated its association with schizophrenia and major depression and its role in the behavioral phenotype of adult mice. Four NGFR SNPs were detected based on a study among 1010 schizophrenia patients, 610 patients with major depressive disorders (MDD) and 1034 normal controls, respectively. We then knocked down the expression of NGFR protein in the hippocampal dentate gyrus of the mouse brain by injection of shRNA lentivirus to further investigate its behavioral effect in mice. We found significant associations of s2072446 and rs11466162 for schizophrenia. Ngfr knockdown mice showed social and behavioral abnormalities, suggesting that it is linked to the etiology of neuropsychiatric disorders. We found significant associations between NGFR and schizophrenia and that Ngfr may contribute to the social behavior of adult mice in the functional study, which provided meaningful clues to the pathogenesis of psychiatric disorders. [ABSTRACT FROM AUTHOR]

A simple, highly selective, and label-free microRNA (miRNA) detection method based on l -alanine-reduced graphene oxide fluorescence quenching with a Y-shaped probe is proposed. The Y-shaped probe was synthesized by silver nitrate and a cytosine-rich molecular beacon (MB) in two terminals through sodium borohydride reduction, which generated a stronger fluorescent signal than ordinary DNA-templated silver nanoclusters (AgNCs). Meanwhile, the Y-shaped probe contained a single-stranded loop structure, which could be superbly adsorbed onto the surface of reduced graphene oxide (RGO) via π–π stacking interaction, and this special structure of the probe was designed to improve its sensitivity and selectivity. In addition, the quenching capacities of graphene oxide (GO) and RGO were compared in this research. The strong interaction between nucleobases of the loop structure and RGO nanosheet made the MB-AgNCs-RGO system exhibit minimal background fluorescence. In the presence of miRNA-21, the loop structure of the Y-shaped probe can hybridize with target miRNA-21; the molecular beacon encapsulated probe is far away from RGO surface and produces a detectable signal. The MB-AgNCs based approach provides a label-free avenue to detect miRNA with high selectivity and good reproducibility, which has a promising application in early clinical diagnosis and biomedical research. [ABSTRACT FROM AUTHOR]

The anti-interference ability of biosensors is critical for detection in biological samples. Fluorescence-based sensors are subject to interference from self-luminescent substances in biological matrices. Therefore, phosphorescent sensors stand out among biosensors due to their lack of self-luminescence background. In this study, a phosphorescent sensor was constructed, which can accurately detect thymidine kinase 1 (TK1) mRNA in biological samples and avoid autofluorescence interference. When there is no target, polydopamine (PDA) is used as the phosphorescence resonance energy transfer (PRET) acceptor to quench the phosphorescence of the persistently luminescent (PL) nanomaterial. When there is a target, the DNA modified by the PL nanomaterial is replaced by the hairpin H and removed away from the PDA, resulting in a rebound in phosphorescence. The phosphorescent sensor exhibits a good linear relationship in the TK1 mRNA concentration range of 0–200 nM, and the detection limit was 1.74 nM. The sensor fabricated in this study can effectively avoid interference from spontaneous fluorescence in complex biological samples, and sensitively and precisely detect TK1 mRNA in serum samples, providing a powerful tool to more accurately detect biomarkers in biological samples. When there is no target, polydopamine (PDA) is used as the acceptor of phosphorescence resonance energy transfer (PRET) to quench the phosphorescence of persistent luminescent nanomaterials (PL). When the target is present, the DNA modified by PL will be replaced by the hairpin H and away from the PDA, resulting in a rebound in phosphorescence. [Display omitted] • Avoid the interference of background fluorescence in complex biological samples. • Phosphorescence biosensor for specific detection of tumor marker TK1 mRNA. • A low detection line of 1.74 nM and a wide detection range were obtained. [ABSTRACT FROM AUTHOR]

MicroRNA (miRNA) imaging has been employed to distinguish cancer cells from normal cells by exploiting the overexpression of miRNA in cancer. Inspired by the acidic extracellular tumor microenvironment, we designed a pH-activated DNA nanomachine to enable the specific detection of cancer cells using miRNA imaging. The DNA nanomachine was engineered by assembling two hairpins (Y1 and Y2) onto the surface of a ZIF-8 metal-organic framework (MOF), which decomposed under acidic conditions to release the adsorbed DNA hairpin molecules in situ. The released hairpins were captured by the target miRNA-21 and underwent catalytic hairpin assembly amplification between Y1 and Y2. The detection limit for miRNA assays using the DNA nanomachine was determined to be 27 pM, which is low enough for sensitive detection in living cells. Living cell imaging of miRNA-21 further corroborated the application of the DNA nanomachine in the identification of cancer cell. [ABSTRACT FROM AUTHOR]

[Display omitted] A portable multi-color colorimetric molecular imprinting polymers sensor for specifically identifing H5N1 from various subtypes influenza A virus with high sensitivity (LOD = 11.6 fM) is constructed. The proposed sensor is cheap (RMB 0.286 Yuan), easy to store and carry, and the detection results can be exhibited by fluorescence, UV-Vis spectrum and naked eyes. • Portable molecularly imprinted sensor. • Ultra-sensitive detection of H5N1 (LOD, 11.6 fM). • Self-service detection of influenza H5N1 with naked eye. • Results presented by three-modes. • Low cost (RMB 0.286 Yuan each). At present, the ability to identify subtypes of influenza A virus (IAV) with high similarity in morphology, size, and surface structure is suffered from significant challenges. In this study, we report on the development of a portable, multi-color, colorimetric molecular imprinting polymer (MIP)-based sensor that can specifically identify H5N1. To construct this sensor, using H5N1 as a template, the MIPs was obtained on the Fe 3 O 4 @ quantum dots (QDs) prepared in advance. Then, the Fe3+@PDA∼ Apt probe, which was designed for specificity for H5N1, was prepared by modifying the H5N1 ∼ Apt on the surface of the pre-prepared Fe3+-embedded dopamine nanoparticles. A sandwich structure would be formed via the specific combination of MIPs, H5N1 and Fe3+@PDA ∼ Apt. During detection, the fluorescence of QDs quenched, achieving the first detection mode of viruses through the change of fluorescence intensity. Subsequently, Fe3+ in the solution was released, K 4 [Fe(CN) 6 ] and K 3 [Fe(CN) 6 ] were added to achieve a multi-color colorimetric detection sensor visible to the naked eyes. The third detection mode can be achieved by detecting the absorbance of the solution by ultraviolet–visible. The sensor was capable of differentiating the target H5N1 virus from other IAV subtypes with high specificity and sensitivity (LOD = 11.6 fM), and the detection of the virus could be enabled by fluorescence spectroscopy, UV–vis spectrophotometry, and colorimetric indication three modes, to provide a reliable point-of-care detection method for ensuring the accurate treatment of patients with H5N1 infection. Importantly, the MIP-based sensor could conveniently achieve the self-service detection at a cost of only RMB in 0.28 yuan. [ABSTRACT FROM AUTHOR]

An approach is reported based on the combination of aptamer and metal organic frameworks (MOF) to prepare a molecularly imprinted sensor that recognizes viruses with high specificity and sensitivity. Using MIL-101-NH2 as a polymer carrier, viral aptamers were introduced into the carrier surface through an amide reaction to specifically identify the target, and surface imprinting is carried out through tetraethyl silicate (TEOS) self-polymerization. The MIL-101-NH2 is also used as the reference fluorescence signal (λex/λem = 290/460 nm) and rhodamine B as the change signal (λex/λem = 550/570 nm). The ratiometric fluorescence detection and dual recognition strategy not only reduce environmental interference but also greatly improve the sensor’s anti-interference ability, the obtained imprinting factor was 5.72, and the detection limit as low as 1.8 pmol L−1. Therefore, the molecular imprinting sensor designed realizes the specific and highly sensitive identification of viruses, which provides theoretical support for the application of molecular imprinting technology in clinical diagnosis of viruses. [ABSTRACT FROM AUTHOR]

Highly selective and highly efficient identification of large viruses has been a major obstacle in the field of virus detection. In this work, a novel sandwich resonance light scattering sensor was designed based on molecularly imprinted polymers (MIPs) and aptamers for the first time. One of the recognition probes was obtained by molecular imprinting using environmentally friendly carbon spheres as carriers and the other by modification of the aptamer that can specifically recognize hepatitis B virus (HBV) on the surface of silicon spheres. In the presence of both probes, an MIP-HBV-aptamer sandwich structure was formed continuously in the system with the increase in HBV concentration, resulting in a strong resonance light scattering response. Finally, satisfactory selectivity and sensitivity were obtained, and the imprinting factor was as high as 7.56, which was higher than that reported in previous works of viral molecular imprinting sensor. In addition, it is of great significance to solve the problem of insufficient selectivity of traditional detection methods for macromolecular targets. [ABSTRACT FROM AUTHOR]

A sensitive ratiometric fluorescence probe based on hybridization chain reaction (HCR) was constructed for sensitive detection of miRNA-21 by using G-triplex and silver nanocluster pairs (AgNC pairs) as an enzyme-free and label-free signal output group. miRNA-21 was used as the primer for the hybridization chain reaction of molecular beacon 1 (MB1) containing the locked G-triplex sequence and molecular beacon 2 (MB2) with intact AgNC pairs at the 5′ and 3′ end activation. The double-stranded product was obtained along with the opening of the G-triplex and the separation of the AgNC pairs. A detection limit of 67 pM and a linear detection range of 0.1–300 nM were obtained for miRNA-21 determination. The proposed strategy enabled the monitoring of miRNA-21 levels in at least three cell lines, indicating that it provided new ideas for detecting miRNA in real samples. [ABSTRACT FROM AUTHOR]

An ultra-sensitive paper-based molecularly imprinted sensor for detection of H5N1 was described. The results can not only be detected quantitatively by fluorescence, but also can be directly read with naked eyes under visible light or ultraviolet light within 10 min. With naked eye detection, its sensitivity is obviously better than that of commercial kits. In particular, the cost of the sensor is cheap (Original size: RMB 1.53 Yuan each; Smaller size: RMB 0.08 Yuan each), which is beneficial to application. [Display omitted] • Paper-based molecularly imprinted sensor; • Ultra-sensitive detection of H5N1 (LOD, 0.58 fM); • Rapid visual detection of influenza H5N1 within 10 min; • More intuitive and sensitive results than commercially available kit; • Low cost (Original size, 1.53 yuan/piece; Smaller size, 0.08 yuan/piece). The rapid detection of pathogens is important to the control of epidemics. Here, a paper-based molecularly imprinted sensor has been developed for the visual detection of influenza H5N1 virus. Firstly, the paper-based molecularly imprinted was prepared by a sol–gel reaction. Then, H5N1 ∼ Apt was covalently bound to the surface of the ZIF-8-NH 2 coated with rhodamine B (RhB) through an amide bond, to produce the fluorescent and colorimetric probe ZIF-8-NH 2 @RhB ∼ Apt. When H5N1 and ZIF-8-NH 2 @RhB ∼ Apt are added to the paper-based MIPs, the H5N1 will be combined with MIPs through the synergistic effects of shape and size compatibility and interaction with the functional groups of the monomers, and ZIF-8-NH 2 @RhB ∼ Apt will bind to H5N1 through its aptamers to form a sandwich structure. The sensor has ultra-high sensitivity and the detection limit is 0.58 fmol/L by using fluorescence spectroscopy. A semi-quantitative signal can also be observed with the naked eye within 10 min. A comparative study showed that direct visual detection was highly reliable, and the sensitivity was better than that achieved with a commercially available kit. Importantly, the paper-based sensor is low in produce cost (Original size: RMB 1.53 Yuan each; Smaller size: RMB 0.08 Yuan each) and is easy to cut, store and carry. This sensor is expected to allow self-service, visual, high-throughput, and real-time virus detection, which is of great significance for epidemic prevention and control. [ABSTRACT FROM AUTHOR]

Boronate affinity molecularly imprinted materials have been widely used for the separation of glycoproteins under alkaline conditions that is not conducive to the structural stability of the protein. In this work, a kind of novel molecularly imprinted polymer (MIP/TBA/MOF@Fe3O4) was prepared via grafting self‐assembled molecular team of boronic acids on the surface of the magnetic metal–organic framework core. The teamed boronate affinity was formed by 2‐mercaptoethylamine and 4‐mercaptophenylboronic acid for specific separation of glycoproteins under physiological pH (pH 7.4). The obtained nanoparticles show high binding capacities (337.8 mg/g), fast adsorption equilibrium time (20 min), and good specificity (imprinting factor, 4.52) for glycoproteins under physiological pH. Furthermore, the prepared imprinted polymer still shows good adsorption capacity for glycoprotein after five times of repeated use, and its adsorption capacity only dropped by 4.7%. More importantly, the prepared nanoparticles have good potential to adsorb glycoproteins from real biological samples. [ABSTRACT FROM AUTHOR]

Molecularly imprinted polymer (HM@MIP) nanoprobes were designed form the pH-responsive polymer (dimethylaminoethyl methacrylate (DMA)) and MIL-101. This probe was applied to the selective determination of hepatitis A virus (HAV) through Resonance light scattering (RLS) technique. DMA adjusts pH of the system to facilitate the capture and release of virus by HM@MIPs as anticipated. And it results in the enhancement or weaken of RLS intensity. According to RLS intensity at 470 nm, a linear concentration of 0.02–2.0 nmol·L−1 and a limit of detection of 0.1 pmol·L−1 were obtained within 20 min. The excellent recoveries ranges from 88% to 107%, and it indicates the prominent ability of the HM@MIPs to determination HAV in human serum and their potential ability to determination virus in real applications. [ABSTRACT FROM AUTHOR]

A method is described for the simultaneous determination of hepatocellular carcinoma-associated microRNA-122 and microRNA-199a/b-3p. This probe consists of two kinds of nanomaterials. The first comprises CdTe@CdS core-shell quantum dots which, on excitation at 375 nm give two emissions, with peak wavelengths at 543 (g-QDs) and at 627 nm (r-QDs). The second comprises gold nanoparticles acting as a quencher. In the absence of the target, g-QD-N1 and r-QD-N2 are stable due to the fluorescence stability. With the addition of microRNA-122 and microRNA-199a/b-3p, g-QD-N1 and r-QD-N2 are conjugated to the surface of AuNP-S1/S2 through base complementary pairing. As a result, fluorescence resonance energy transfer (FRET) occurs, resulting in a decrease at 550 nm and 635 nm respectively, which can realize the simultaneous detection of two different microRNAs. Detection is achieved within 50 min. The detection limits (3σ/k) are 0.2 nM for microRNA-122 and 0.5 nM for microRNA-199a/b-3p. The clinical applicability of the assay was demonstrated by detecting microRNAs in human serum and different cell lysates. [ABSTRACT FROM AUTHOR]

Because rapid, convenient, and selective methods for HIV detection are urgently needed, herein, a simple label-free and enzyme-free strategy is constructed for sensitive fluorescence detection of HIV DNA using the fluorescent intercalating dye thioflavin T (THT) as the detection signal source. This strategy utilizes a hairpin DNA sequence (H1) and two assistant strands. H1 is wisely designed with a G-quadruplex sequence in the stem. Target DNA, when present in solution, will hybridize with H1 to form H1/target duplexes and release the G-quadruplexes. Additionally, the assistant probes hybridize with the unfolded H1 to form a stable DNA double strand, resulting in the displacement of the target to participate in another similar reaction cycle. Consequently, many G-quadruplex structures are generated, leading to a significantly amplified fluorescence signal of THT. The linear range is from 0.1 nM to 50.0 nM with a limit of detection of 13 pM. Results can be achieved within 40 min, because the cyclic amplification involves only one DNA hairpin and two auxiliary chains. Furthermore, this platform exhibited good selectivity with one base mismatch or other DNA sequences. This strategy could be used as a simple, sensitive, and selective tool to detect other DNA biomarkers. [ABSTRACT FROM AUTHOR]

A molecular beacons (MBs) loaded on molybdenum disulfide (MoS 2) nanosheets as fluorescence probes for sensitive and versatile detection of microRNAs (miRNAs) through hybridization chain reaction (HCR) has been designed. MoS 2 was used as a adsorbent to capture the MBs and a selective fluorescence quencher to reduce the background signal. In the absence of miRNAs, HCR could not be triggered due to the stability of MB probes. The probes attached to the MoS 2 surface, efficiently quenching fluorescence of the G-quadruplex/Thioflavin T. However, the presence of target miRNAs triggers the HCR process to generate large amount of HCR products. Meanwhile, the HCR products of long nanowires chain with abundant G-quadruplexes could not be adsorbed on the surface of MoS 2 , and therefore detach from the MoS 2. Consequently, Thioflavin T could be embedded in G-quadruplexes and produced strong fluorescence signal. This fluorescence emission signal could achieve detection of miRNA as low as 4.2 pM and a wide linear ranges from 0.1 to 100 nM. In addition, a versatile fluorescence probe has been developed for detection of miRNA-21 by changing the miRNA-recognition domain of MB. Thus, the fluorescent probe would be a potential alternative tool for biomedical research and clinical molecular diagnostics. MB1 and MB2 hairpins DNA can absorb onto MoS 2 nanosheets without target miRNA. In the presence of target, it can opened the hairpin structure of MB1 and caused the rest sequence of MB1 to bind with parts of MB2. Similarly, after MB2 was opened, the exposed parts of MB1 hybridized with the complementary sequences of another MB2. Such HCRs can generate a long MB1-MB2 duplex chain which desorbed from MoS 2 nanosheets and the fluorescence intensity of G-quadruplex/ThT was recoveried. Image 1 • A low-background MoS 2 nanosheets-loaded molecular beacon probe with signal amplification by HCR technology for different miRNAs detection. • This lable-free and enzyme-free, high selectivity, cost-saving miRNAs detection assay with the limit of detection as low as 4.2 pM. • MiRNAs detection in cell lysates with satisfactory results. [ABSTRACT FROM AUTHOR]

A magnetic surface molecularly imprinted-resonance light scattering sensor was developed for rapid and highly sensitive detection of Japanese encephalitis virus (JEV). To prepare the surface imprinted polymer, Fe 3 O 4 microspheres were selected as imprinting substrates which coated by silicon. Aminopropyl-triethoxysilane (APTES) as functional monomers for fixing template molecules JEV through a polymerization process of tetraethyl-orthosilicate (TEOS). The target virus JEV could be captured by the imprinted particles fastly and selectively, resulting in an increase of the RLS intensity. The results of RLS analysis proved that the obtained imprinted nanoparticles exhibited excellent specific recognition ability and high selectivity for the template virus (JEV). Furthermore, the response time of the sensor is within 20 min, which is much shorter than the previous works. The sensor with convenient separation and the limit of detection was 1.3 pM. These experimental results show that the proposed strategy is expected to achieve rapid and sensitive detection of JEV in practical applications. Amino-modified Fe 3 O 4 @ SiO 2 nanoparticles were prepared by modifying Fe 3 O 4 with tetraethylorthosilicate and aminopropyltriethoxysilane. JEV was used as a template to obtain virus-imprinted polymer. The resulting imprinted nanoparticles can capture the target virus quickly and sensitively, resulting in increased RLS intensity. This method can not only show high selectivity, but also can be used for quantitative detection of JEV in a wide linear range, thus it provides new ideas for the effective detection of viruses. Image 1 • This MIPs-RLS sensor can detect JEV selectively with a detection limit of 1.3 pM. • The obtained nanoparticles can be magnetically separated and eluted by using Fe 3 O 4. • The proposed assay can achieve rapid detection for JEV within 20 min. [ABSTRACT FROM AUTHOR]

Tumor-related mRNA detection is significant and interesting. The current mRNA detection method has the challenge of quantifying long mRNA sequences. Herein, a Y-shaped DNA probe with three target-binding segments was developed to detect tumor-related mRNA. This Y-shaped DNA probe (Y-probe) was assembled by six single DNA strands. Among these DNA strands, two DNA strands contained the split G-quadruplex sequence, and two DNA strands were modified with a pair of fluorophore and quencher, which were used to produce the detectable signal. In the presence of a long target mRNA sequence, target mRNA was hybridized with the three target-binding segments of the Y-probe, resulting in the increased fluorescence of G-quadruplex specific dye Thioflavin T and the decreased fluorescence of fluorophore, which could achieve the ratio detection of target mRNA. The Y-probe exhibited a low detection limit of 17.53 nM. Moreover, this probe showed high accuracy due to the benefits of three target-binding segments. Schematic illustration of the Y-probe for detection of survivin mRNA. [Display omitted] • A Y-shaped DNA probe with three target-binding segments was developed to detect tumor-related mRNA. • A ratiometric measurement probe was constructed using the spatial location of the fluorophore. • This mechanism showed high accuracy due to the benefits of three target-binding segments. [ABSTRACT FROM AUTHOR]

In the absence of target, GQDs-H coexisted stably in solution to produced a low resonance light scattering (RLS) signal. The addition of the target caused the self-assembly of catalytic hairpins of H1 and H2, and the release of the target initiated a cyclic reaction. A large amount of GQDs-H1:H2-GQDs aggregates were produced, resulting in a significantly RLS signal. • A novel GQDs-based RLS biosensor with signal amplification by CHA reaction was developed. • The proposed biosensor is simple, enzyme-free, highly selective and ultrasensitive for mutant DNA detection and the limit of detection is as low as 0.8 pmol L-1. • Targets in real sample were detected with satisfactory results. In this work, a simple, enzyme-free and ultrasensitive resonance light scattering (RLS) method was developed based on graphene quantum dots (GQDs) with a catalytic hairpin assembly amplification strategy for selective detection of mutant DNA. This method contains two probes, GQDs-H1 and GQDs-H2. Two partially complementary hairpins (H1 and H2) are ingeniously and rationally designed, and they can't spontaneously hybridize with each other in the absence of target. When the target is added, the target binds with GQDs-H1 and forms GQDs-H1: target intermediates. Then, GQDs-H2 hybridizes with the GQDs-H1: target and frees the target, triggering another reaction cycle. A large amount of GQDs-H1:H2-GQDs aggregates are formed, which obviously increase the RLS signals. A limit of detection of 0.8 pmol L−1 and two linear ranges of 1.0 pmol L−1–1.5 nmol L−1 and 1.5–50.0 nmol L−1 for target detection are obtained. This detection method is simple, available, and low-cost. It can be potentially applied to other DNA detection and broadens the sensing application of GQDs for the detection of other significant disease-related markers. [ABSTRACT FROM AUTHOR]

Abstract A rapid, label-free, and multifunctional fluorescent probe for simultaneous detection of multiple targets was fabricated based on G-quadruplexes and DNA-templated silver nanoclusters (AgNCs). In this work, a probe with two capitated recognized regions was coupled with a locked G-quadruplex at the 5′-terminus and dark AgNC at the 3′-terminus. Upon the addition of the virus subtype H5N1 gene or microRNA-141, only the sequence of the G-quadruplex was released and bound with Thioflavin T (ThT) for a specific fluorescent response. On the contrary, with the presence of the influenza virus subtype H1N1 gene or microRNA-21, the fluorescence intensity was enhanced because of two split AgNCs approaching closely to produce a nanocluster dimer. Subsequently, with multiple target addition, fluorescence signals were produced for both G-quadruplexes and AgNCs. Moreover, this single and duplex detection for virus DNAs and microRNAs, which provides a versatile platform for different targets, was sufficiently sensitive for the expected detection limit, and still possessed unique selectivity with similar oligonucleotides. The simultaneous detection of targets in biological fluids indicated that there is great opportunity for this strategy to be further applied in biomedical research and clinical diagnosis. Graphical abstract Image 1 Highlights • A rapid, label-free and multifunctional fluorescent probe was fabricated to overcome cumbersome labeling procedures. • The system based on G-quadruplexes and DNA-templated silver nanoclusters (AgNCs) was designed for improving the sensitivity for simultaneous detection of virus DNA and microRNA. • The proposed strategy exhibited special selectivity in similar oligonucleotides and could be well applied in biological fluids. • The detection limit for H5N1 and H1N1 was estimated to be 0.45 nM and 10 nM respectively, and for miRNA-141 and miRNA-21was 1 nM and 10 nM respectively. [ABSTRACT FROM AUTHOR]

Highlights • The plasma concentration of iPLA2 was increased in schizophrenia while cPLA2 not. • Meta-analysis showed the iPLA2 in schizophrenia was increased while cPLA2 was not. • The correlation between the iPLA2 and skin flushing response was positive. Abstract Evidence indicates that abnormal phospholipase A2 (PLA2) levels and niacin insensitivity are present in individuals with schizophrenia. This study was designed to determine whether differences in plasma calcium-independent phospholipase A2 (iPLA2) and cytosolic phospholipase A2 (cPLA2) exist between those with schizophrenia and healthy controls, and to explore the correlation between PLA2s and the niacin skin reaction in schizophrenic patients. We performed ELISA experiments to measure the concentrations of plasma iPLA2 and cPLA2 and we conducted a series of niacin skin tests on schizophrenic patients from the Chinese Han population. In addition, a meta-analysis of the relationship between PLA2 and schizophrenia was conducted. The plasma concentration of iPLA2 in patients with schizophrenia was significantly higher than that in healthy controls while the plasma concentration of cPLA2 did not differ. The meta-analysis also revealed that the activity level of iPLA2 in individuals with schizophrenia was higher than that in healthy controls, whereas that of cPLA2 was not. Furthermore, a significant positive correlation was found between the concentration of iPLA2 and the score for the skin flushing response within 20 min. The abnormal plasma iPLA2 concentration and its relationship with the niacin skin test in schizophrenic patients has contributed to a deeper understanding of the pathology of schizophrenia, which may in turn provide new insights into the clinical diagnoses and treatment of schizophrenia. [ABSTRACT FROM AUTHOR]

Abstract A fluorescent biosensing strategy based on three helix molecular beacons (tMBs) for simultaneous simple and rapid detection of HIV related genes was developed. This tMBs contain outer loop sequences and fluorescent probes. The outer loop sequences consist of target capture sequences (cDNA) and the stems can lock the fluorescent probes (P). Initially, the probes were tethered to display weak fluorescence signals in the tMBs. Once the target DNAs opened loops, the stems of tMBs were dehybridized which resulted in turning on the fluorescence. By applying tMBs fluorescent switch detection strategy, the fluorescence response at 484 nm and 367 nm were corresponding to thioflavin (THT) and 2-aminopurine (2-AP) respectively with high selectivity and sensitivity. The detection limits were calculated to be 227 pM for HIV-1 and 352 pM for HIV-2, respectively. As a general detection model for multiple species, the proposed strategy exhibits outstanding analytical performance such as simple, low-cost, and high anti-interference capability, which provides a new and ultrasensitive biosensing platform for multiple DNAs simultaneous detection in biomedical research and early clinical diagnosis. [ABSTRACT FROM AUTHOR]

In this study, an intelligent and label-free sensor is utilized for the first time to one-spot simultaneous detection hepatocellular carcinoma markers AFP and miRNA-122 by a resonance light scattering (RLS) sensor. cDNA1 hybridizes with cDNA2 to form double-stranded DNA (dsDNA). The construction of dsDNA and methyl violet is used to form the RLS sensor via the electronic interaction. When AFP or miRNA-122 is present, the cDNA (cDNA1 or cDNA2) can bindings of target, thereby RLS intensity changed proportionally with the concentration of AFP or that of miRNA-122. The detection limits of AFP and miRNA-122 are 0.94 μg/L and 98 pM respectively, and their good linear which ranges from 5 to 100 μg/L and 200 pM to 10 nM are achieved using the assay. In the presence of miRNA-122 and AFP mixtures, AFP bound to the AFP aptamer to increase the RLS signal, and miRNA-122 bound to the miRNA-122 complementary strand to decrease the RLS signal. The RLS signal changed in response to changing AFP and miRNA-122 concentrations, so that one-spot simultaneous detection of alpha fetal protein and miRNA-122 is achieved. This method has potential practical applications in the research of hepatocellular carcinoma. [ABSTRACT FROM AUTHOR]

An efficient dual-amplification system based on catalyzed hairpin assembly (CHA) amplification and hybridization chain reaction (HCR) circuits is developed for G-quadruplex-based and non-enzymatic fluorescence detection of microRNA. Four hairpin probes, namely, H1, H2, H3, and H4, are excellently designed to coexist metastably without a target. Upon the addition of the target, H1 recognizes the target and releases the G-quadruplexes. Meanwhile, H2 fully hybridizes with H1 to form stable H1/H2 duplex that leads to the replacement of the target for participating in another cycle. Moreover, the newly formed product of CHA cycles, H1/H2 duplex, hybridizes with H3 and frees the trigger to open HCR circuits, resulting in the cross-opening of H3 and H4 and self-assembling into a long DNA nanowire with abundant G-quadruplexes. Consequently, many G-quadruplex structures are formed and further combined with thioflavin T for significant fluorescence enhancement. The proposed system can detect miRNA in a wide concentration range with the detection limit as low as 36 fM and can exhibit special selectivity in homologous miRNA sequences. Moreover, this detection assay can be well applied in cancer cell samples, which possesses enormous potential to show novel perspectives in the analysis of biomarkers, clinical diagnostics, and biomedical applications. [ABSTRACT FROM AUTHOR]

Rapid and sensitive detection of thrombin has very important significance in biomedical and bioanalytical applications. In this study, a label-free and simple resonance light scattering (RLS) sensor based on MoS 2 nanomaterial is developed for ultrasensitive and highly selective detection of thrombin. In the presence of thrombin, the thrombin aptamer can transform into a G-quartet structure and combine with thrombin, resulting in dissociation of the random DNA (rDNA) in the solution. Once MoS 2 is introduced, the free rDNA can be adsorbed on the surface of MoS 2 to form a stable DNA1–thrombin–MoS 2 complex, which increases RLS signals. The sensor shows two linear ranges of 10 pM to 500 pM and 1 nM to 60 nM, and a detection limit of 0:71 pMfor detection of thrombin. Our sensor is a promising tool for clinical diagnosis of thrombin in human serum. Moreover, this work can offer new opportunities for the development of convenient sensor for detecting other proteins. [ABSTRACT FROM AUTHOR]

This study demonstrated fluorescent detection of Japanese encephalitis virus (JEV) by surface molecularly imprinted technique. After dansyl chloride (DNS-Cl) was immobilized on silica microspheres (SiMP) with JEV as the template, (3-aminopropyl)triethoxysilane (APTES) as the monomer and tetraethyl orthosilicate (TEOS) as the cross-linker was mixed with SiMP, and the polymerization was performed in mild condition. After polymerization, templates were removed to obtain JEV-imprinted polymers (JEV-MIPs). The obtained JEV-MIPs can selectively recognize JEV in the presence of Hepatitis A virus (HAV), Simian virus 40 (SV40) and Rabies virus (RV), and also sensitively detect JEV with a picomolar detection limit. [ABSTRACT FROM AUTHOR]

Based on 2-aminopurine (2-AP) probe in conjunction with a G-quadruplex structure and signal amplification technique, a simple and highly sensitive fluorescence sensor for detecting microRNA (miRNA) is developed for high signal-to-background ratio and wide linear range. The proposed sensor contains two hairpins DNA: H1 and H2. H1 is labeled by 2-AP incorporated into a G-rich sequence. Upon the addition of a target miRNA, H1 is unfolded and forms DNA/RNA complexes that contain a G-quadruplex, thereby significantly enhancing 2-AP fluorescence due to the protection provided by the G-quadruplex. Subsequently, H2 can displace the miRNA from the DNA/RNA complexes and induce signal amplification, resulting in further enhanced fluorescence intensity. Hence, the sensor is highly sensitive and its low limit of detection (L.O.D.) can reach as low as 1.48 pM. Furthermore, the proposed sensor is used to detect overexpressed miRNA-21 from human breast cancer cell lysate. The result demonstrates the potential of the proposed sensor to monitor different miRNA biomarkers for the early diagnosis of various cancers. [ABSTRACT FROM AUTHOR]

A facile and cost-effective fluorescence biosensor is constructed for the accurate and sensitive determination of DNA. The G-quadruplex-forming sequence in hairpin DNA sequence (H1) is originally locked. When target DNA is present, the hairpin structure of H1 can be unfolded and part of H1 hybridized with the target DNA to form a double-stranded DNA and a G-quadruplex. The hairpin DNA sequence (H2) hybridizes with the unfolded H1 and displaces the target DNA. Finally, the displaced target DNA again hybridizes with the H1 and initiates cycle amplification. Thus, the numerous G-quadruplexs at the H1 ends are formed, resulting in the fluorescent enhancement after binding with N-methyl mesoporphyrin IX (NMM). Lower background signal improves the accuracy of assay. The enzyme-free method can detect down to 40 pM and a linear range of 3 orders of magnitude. Moreover, this strategy has an ability to discriminate the target DNA from even single-base mismatched or other sequence. The proposed method has potential applications in DNA-based molecular diagnostics. [ABSTRACT FROM AUTHOR]

In this study, a thermosensitive imprinted polymer coating SiO 2 was developed for a resonance light scattering (RLS) thermosensitive virus-affinity sensor, which exhibited high selectivity for virus monitoring. In this sensor, N -isopropylacrylamide was a temperature-sensitive element. The recognition performance of the nanosensor for viruses was regulated by temperature control for the specific capture of the target virus at 40 °C, resulting in the increase of RLS intensity and its release at 20 °C. Moreover, the RLS intensity of the nanosensor significantly increased within 30 min. Accordingly, a very good detection limit of 1.1 pmol L −1 was obtained. The nanosensor was successfully used to detect the additional hepatitis A virus from a dilution of human serum, and recoveries in the range of 90.8% to 108.3% were attained at three spiking levels of viruses. Overall, this study addressed the problems of high nonspecific adsorption and long duration of detection process. Furthermore, a facile, rapid, and efficient tool for virus detection was provided. [ABSTRACT FROM AUTHOR]

An interference-free and label-free sensing platform was developed for the highly sensitive detection of microRNA-21 (miRNA-21) in vitro by magnetic silicon microsphere (MNP)-reduced graphene oxide (rGO)-based sandwich probe. In this method, DNA capture probes (P 1 ) were connected with MNPs at the 5′ end and hybridized with completely complementary target miRNA. Subsequently, rGO was retained and induced the fluorescence quenching in the supernatant. Through the magnetic separation, the supernatant environment was simplified and the interference to analytical signal was eliminated. When DNA capture probe-modified magnetic silicon microspheres (MNP-P 1 ) were adsorbed through rGO in the absence of a target and formed a sandwich structure, the formed nanostructure was easily removed from the solution by a magnetic field and the fluorescence intensity was maximally recovered. This proposed strategy, which both overcame the expensive and cumbersome fluorescent labeling, and eliminated interference to analytical signal for guaranteeing high signal-to-background ratio, exhibited high sensitivity with a detection limit as low as 0.098 nM and special selectivity toward miRNA-21. The method was potentially applicable for not only detection of miRNA-21 but also various biomarker analyses just by changing capture probes. [ABSTRACT FROM AUTHOR]