Search

We reported a novel strategy that combined a Cu-based metal–organic gel (Cu-MOG) with an entropy-driven circuit (EDC) to detect miR-155 as a proof-of-principle target.

Carbon dots have promising prospects for analytical and monitoring purposes, but are greatly hindered by the aggregation-induced luminescence quenching owing to the π-π interaction or the non-radiation-excited radical complex formation. Herein hydrothermally prepared orange-yellow fluorescent carbon dots (O-CDs) show an aggregation-induced fluorescence enhancement (AIFE) with Cu

Inspired by the specific optical properties of DNA photonic nanowires (PNs) on which fluorescent dyes are to be precisely positioned and photonic energy transfer over nanometers can be achieved, he...

The expression level of nucleic acids is closely related to a variety of diseases. Herein, a highly sensitive detection of a nucleic acid based on a CoOOH-luminol chemiluminescence (CL) system without the addition of oxidants was proposed by the toehold-mediated strand displacement reaction (TSDR) and the liposome dual signal amplification strategy with the hybrid probe formed by linking soft nanoballs (SNBs) to magnetic beads (MBs) through DNA hybridization. Inspired by the free radical scavenging effect of the as-prepared carbon dots (CDs), CDs were successfully employed to quench the CL intensity of the CoOOH-luminol system. And the CDs were further encapsulated into liposomes to construct SNBs, which avoided the complex modification of CDs to maintain their original properties, as well as loaded a large number of CDs to scavenge free radicals to achieve signal amplification. Based on this, target DNA (tDNA) could be sensitively detected based on the reduced CL intensity, which achieved a dynamic detection range from 0.1 nM to 20 nM with a limit of detection as low as 59 pM (3σ/k), showing amazing promise in the biosensing of nucleic acid biomarkers.

DNA nanomachines, a delicate type of molecular machines, have been a research hotspot in biotechnology and materials. Here a two-dimensional (2D) DNA walking nanomachine with high working efficiency and low cost was easily assembled by using graphene oxide (GO) as the working platform for precisely fluorescent bioassay through the binding of target hepatitis B virus DNA (HBV-DNA) and the driving force of Exonuclease III (Exo III). The presence of HBV-DNA made continuous Exo III digestion of the FAM-modified DNA (FAM-DNA) in double-strand DNA (dsDNA) part in a burnt-bridge mechanism to output a "one-to-more" amplified signal. Accordingly, a 2D DNA walking nanomachine with simple operation and high cost-performance ratio was constructed. The walking speed of nanomachine was found to be regulated by loading DNA density on single sheet of GO. Furthermore, this nanomachine had low background since the dual energy transfer including fluorescence resonance energy transfer (FRET) from FAM to BHQ1 and the long-range resonance energy transfer (LrRET) from FAM to GO, making the biosensing applications highly promising.

DNA-based nanomachines have aroused tremendous interest because of their potential applications in bioimaging, biocomputing, and diagnostic treatment. Herein, we constructed a novel exonuclease III-propelled and signal-amplified stochastic DNA walker that autonomously walked on a spherical particle-based 3D track through a burnt-bridge mechanism, during which nanosurface energy transfer (NSET) occurred between the fluorescent dye modified on hairpin DNA and the surface of gold nanoparticles (AuNPs). As a proof of concept, this stochastic DNA walker achieves prominent detection performance of HIV DNA in the range of 0.05–1.2 nM with a detection limit of 12.7 pM and satisfactory recovery in blood serum, showing high promise in biosensing applications with complicated media.

Fluorescent labeled single-stranded DNA (ssDNA) molecules physisorbed on graphene oxide (GO) have been extensively explored as a useful sensing platform. However, this approach faces challenges when applied to complex biological samples due to heavy nonspecific desorption of nontarget molecules from GO. To overcome this problem, we introduced a capture DNA (cDNA) fragment with a poly adenine (poly-A) extension into the physisorption system that greatly reduces nonspecific desorption and false positive signal due to strong binding between poly-A and GO. Fluorescence from the dye can be effectively quenched by BHQ, which thus provides a second guarantee of anti-interference to avoid possible nonspecific poly-A DNA displacement. As a proof of concept, we have successfully developed a novel DNA-adsorbing GO nanocomplex probe (DNA-GO nanocomplex probe). This probe has a high anti-interference capability and low background due to the presence of both GO and black hole quencher (BHQ) as a dual-quencher that reduces the background in live cell imaging due to resonance energy transfer (RET). We then employed the DNA-GO nanocomplex probe for simultaneous detection of miR-630 and miR-21 and also for simultaneous in situ dynamic monitoring of intracellular miR-630 and miR-21 in apoptotic cells. We discovered that miR-630 expression was up-regulated during the first 120 min. This simple but powerful protocol has great potential in precise detection and imaging of various substances in complex biological samples with improved accuracy.

Nitrite (NO2−) is one of the important pollutants in food and the environment, which can seriously endanger the health of human beings. Therefore, detecting nitrite in food, environmental and biological samples is very significant for health monitoring. Herein, polymer carbon dots (PCDs) doped with nitrogen and phosphorus were prepared by polymerization of ascorbic acid (AA) and polyethylenimine (PEI) with phosphoric acid, and exhibited excellent stability, adjustable fluorescence emissions and good biocompatibility. It was found that the PCDs presented a sensitive response to nitrite (NO2−), and they were successfully applied for NO2− analysis in water and milk samples, and the dynamic monitoring of nitrite entry into Hep-2 cells.

A simple and fast method for copper ions (Cu2+) and silver ions (Ag+) detection was established with cadmium telluride quantum dots (CdTe QDs) as fluorescent probes. In the presence of Cu2+ or Ag+, the fluorescence intensity of TGA-CdTe QD can be significantly quenched, which fitted a linear relationship between the fluorescence quenching degree (F0-F)/F0 and the concentration of metal ions. In this work, the lowest detected concentration for Cu2+ and Ag+ was 35.0 nM and 25.3 nM, respectively. In addition, the differentiation of Cu2+ and Ag+ at different concentrations was realized with the principal component analysis (PCA). Furthermore, Cu2+ was successfully detected in body fluids. This method provides a good potential for copper ions and silver ions detection with simplicity, rapidity, and excellent selectivity.

Gemcitabine (Gem) is currently the first-line chemotherapeutic drug in management of pancreatic cancer, however the therapeutic efficacy of Gem is limited due to its short half-life and poor cell membrane permeability. Here we designed mesoporous silica vesicles (MSVs) with large pore sizes as a novel drug delivery system. The MSVs were synthesized using cetyltrimethyl ammonium bromide (CTAB) as a structure-directing agent, tetraethoxysilane (TEOS) as silica source in n-hexane/water biliquid system. By virtue of the large pore size and large pore volume of the MSVs, Gem was loaded into the mesoporous of MSVs via nanocasting method. In vitro drug release experiments of gemcitabine-loaded MSVs showed an accelerating release of gemcitabine in acidic condition. These fluorescently labeled MSVs could be effectively internalized by both a human (BxPC-3) and a mouse pancreatic cancer cell lines (Pan02). Additionally, some MSVs could even reach the nuclei of the pancreatic cancer cells. Cell viability assays demonstrated that gemcitabine-loaded MSVs exhibited enhanced anticancer activity in inhibiting the proliferation of BxPC-3 and Pan02 cells compared with free Gem, while the MSVs alone showed no significant cytotoxicity. Our results indicate that our synthesized MSVs might represent a promising novel drug delivery platform for the treatment of pancreatic cancer. This work was supported by National Natural Science Foundation of China (Nos. 51372041, 51422202), the Shanghai Committee of Science and Technology (No. 13140902401), the ShuGuang Project (No. 13SG02) of Shanghai Municipal Education Commission, Shanghai Municipal Science and Technology Commission (No. 13140902401), National Youth Top-notch Talent Support Program in China, and Qatar University (No. QUUG-CAS-DMST-1516-18). The authors extend their sincere appreciations to the Deanship of Scientific Research at King Saud University for its funding this Prolific Research group (No. PRG-1437-32). Scopus

Six typical red clay profiles were sampled from Tangxi (TX), Langyaz (LYZ), South Shangshanwen (SSW), Xianqiao (XQ), Qijian (QJ) and Huhaitang (HHT) of Jinhua-Quzhou Basin, Zhejiang Province of China to evaluate the characteristics of grain size composition, distribution and parameters of red clays and to reveal the origin of red clays and interpret possible implications for paleoclimate in subtropical China. The results showed that red clays in TX, LYZ and SSW were fine and uniform, with no > 2 mm gravels and little > 63 μm fraction. They had a high content of 10–50 μm fraction, so-called “basic dust fraction”, and showed unimodal distributions, which were very comparable to those of the Xiashu Loess in southeastern China and the loess in North China. All these features reflected marked aeolian characteristics of the red clays in these areas. Red clays in XQ and QJ were much coarser than those in TX, LYZ and SSW, with high contents of > 63 μm fraction and even containing > 2 mm gravels in some layers. The grain size distribution patterns showed significantly progressive trends from the lower profile to the upmost layer and could not be compared with those of the loess in North China or the Xiashu Loess, implying they might be derived from underlying parent rocks and had some inherited properties from bedrock. Red clays in HHT had high contents of > 63 μm fraction and contain many > 2 mm gravels in each layer. The grain size frequency curves showed multiple-peaks and some abrupt variations were also observed on the profile, revealing its alluvial or diluvial origin in HHT. The multiple origins of red clays reflected the diversity and complexity of the Quaternary environment in South China. It can be concluded that grain size is an effective proxy indicator for the origin of most deposits.

Multi-centric solid-pseudopapillary neoplasm (SPN) of the pancreas is a rare tumor: only 4 cases are reported in the literature. The clinical and pathological features have not yet been fully clarified. We report 3 cases of multi-centric SPN and discuss their clinical presentations and histological and immunohistochemical features, comparing with solitary SPN. Among the total of 7 cases, 6 were female and 1 was male. Patients had nonspecific symptoms at presentation. Tumors were often large and well demarcated with cystic degeneration and clear margin between lumps. Histologically, characteristic pseudopapilla was formed with uniform cells surrounding the delicate blood vessels. Tumor cells were positive for vimentin, synaptophysin, progesterone receptor, and CD10 and demonstrated nuclear localization of β-catenin. The prognosis of patients was excellent after complete surgical resections. Multi-centric SPN shares similar clinical and pathological features to solitary SPN.

e15266 Background: The preoperative identification of pancreatic cystic neoplasms (PCNs) is crucial to the surgical decision-making. Besides pursuing better imaging and laboratory techniques, this ...

To determine the contents of thymidine phosphorylase (TP) and dihydropyrimidine dehydrogenase (DPD) in pancreatic cancer to provide a basis for the clinical use of capecitabine in pancreatic cancer patients.The contents of TP and DPD in pancreatic cancer and adjacent normal tissues from 20 patients were determined by ELISA and the TP to DPD ratios in the cancer and adjacent normal tissue were compared.TP content was 5- to 283-fold higher in tumor tissue (mean 74-fold) than in the adjacent normal tissue (P0.01). DPD in the cancer tissue increased significantly. So did the TP to DPD ratio, when compared to that in normal pancreatic tissue (P0.01).The increased TP to DPD ratio in pancreatic cancer suggests that capecitabine could be activated by the cancer, these capable of selectively kill the tumor cells.

e14651 Background: Early lymph node metastasis is one of the most important characteristic features of pancreatic ductal adenocarcinoma (PDAC) with a dismal prognosis. MicroRNAs (miRNAs) have been shown to have a role in oncogenesis, invasion, and metastasis via epigenetic posttranscriptional gene regulation. However lymphatic metastasis related miRNAs of pancreatic cancer (PC) has not been well documented. Methods: Through microarray analysis aberrantly expressing miRNAs potentially regulating lymphatic metastasis in PC were gained from PDAC tissue specimens and cell lines. Candidate miRNAs were confirmed in total 40 resected PDAC cases and cell lines by quantitative reverse transcription-PCR (qRT-PCR). In situ hybridization was performed to elucidate the expression features of miRNA-218 in PDAC, precursor lesions, metastatic lymph nodes and cell lines. Results: MiRNA-218 and other five miRNAs were found aberrantly expressing both in PDAC and BxPC-3-LN5 (cell line with high-metastasis characteristics) by microarray analysis. Down-regulated expression of miRNA-218 was validated in PDAC tissue samples (4 fold decrease) compared to adjacent benign tissue (p=0.006) and cell line BxPC-3-LN5 (3 fold decrease) compared to BxPC-3 (p=0.01). Clinicopathological data demonstrated inverse correlation of miRNA-218 expression with lymph node metastasis (p=0.045). Expression of miRNA-218 was down-regulated in IPMN and even decreased in PDAC in a grade-dependent manner. Almost negative expression of miRNA-218 was revealed in metastatic lymph nodes. Conclusions: Down-regulated expression of miRNA-218 in PDAC and its expression features in precursor lesions suggests a tumor suppressor action of miRNA-218 in PDAC. Decreased expression of miRNA-218 may be associated with lymphatic metastasis of PDAC and interpret the high-metastasis ability of BxPC-3-LN5 cell line.

Systems Metabolic Engineering: The Creation of Microbial Cell Factories by Rational Metabolic Design and Evolution, by Chikara Furusawa, Takaaki Horinouchi, Takashi Hirasawa, Hiroshi Shimizu.- Impacts of Quorum Sensing on Microbial Metabolism and Human Health, by Yang-Chun Yong, Jian-Jiang Zhong.- CHO Glycosylation Mutants as Potential Host Cells to Produce Therapeutic Proteins with Enhanced Efficacy, by Peiqing Zhang, Kah Fai Chan, Ryan Haryadi, Muriel Bardor, Zhiwei Song.- Cell-Free Biosystems for Biomanufacturing, by Chun You, Y.-H. Percival Zhang.- Lipid Bilayer Membrane Arrays: Fabrication and Applications, by Xiaojun Han, Guodong Qi, Xingtao Xu, Lei Wang.- RNA Aptamers: A Review of Recent Trends and Applications, by Kyung-Nam Kang, Yoon-Sik Lee.