Electrochemical determination of caspase-3 using signal amplification by HeLa cells modified with silver nanoparticles.

An electrochemical sensor capable of quantitative determination of caspase-3 activities was developed. A thiolated peptide whose sequence contained a caspase-3 cleaved site and a cell penetration sequence was preimmobilized onto an electrode. The quantification of caspase-3 was accomplished after cell penetration and the subsequent adsorption of silver nanoparticles (AgNPs). The oxidation current of AgNPs was found to be inversely proportional to the concentration of caspase-3 between 0.02 and 0.2 U/mL. A detection limit of 0.02 U/mL for caspase-3 was achieved due to the large number of positively charged AgNPs adsorbed onto the negatively charged cells. The proof of concept was demonstrated by monitoring the cleavage of surface-confined peptide substrates by caspase-3 in cell lysates. The current sensor could be extended to detect cells by replacing the surface-confined peptide with aptamers that recognize cells. Thus, the use of a cell as a matrix for AgNPs shows excellent potential for constructing electrochemical sensors and provides a useful alternative for sensor development in the future. Cells modified with silver nanoparticles were utilized as the electrochemical readout of an electrochemical assay.

Hyaluronic Acid-Modified Porous Carbon-Coated Fe3O4 Nanoparticles for Magnetic Resonance Imaging-Guided Photothermal/Chemotherapy of Tumors.

Chemotherapy is an effective method for treating cancer, clinically. However, side effects of drug and multidrug resistance restrict its application. In recent years, the combined treatment of chemotherapy and photothermal therapy (PTT) is becoming a promising method for treating cancer. PTT utilizes nanomaterials absorbing near-infrared light and producing heat to acquire advanced hyperthermia strategy for cancer treatment. Carbon nanomaterials with good biocompatibility, high surface area, and excellent photothermal properties are an excellent nanoplatform for drug delivery and PTT. Herein, porous carbon-coated magnetite nanoparticles (PCCMNs) were successfully synthesized by a one-pot solvothermal method. Magnetite, a contrast agent, can be used for magnetic resonance imaging. Hyaluronic acid was used to modify the PCCMNs to achieve targeted therapy. The obtained nanohybrid with a good photothermal effect can realize combined PTT/chemotherapy and will be a promising nanoplatform for high efficacy theranostics.

Sensitive Hg2+ Sensing via Quenching the Fluorescence of the Complex between Polythymine and 5,10,15,20-tetrakis(N-methyl-4-pyridyl) Porphyrin (TMPyP).

The interaction between polythymine (dTn) and 5,10,15,20-tetrakis(N-methyl-4-pyridyl) porphyrin (TMPyP) was systematically studied using various techniques. dTn remarkably enhanced the fluorescence intensity of TMPyP as compared to other oligonucleotides. The enhanced fluorescence intensity and the shift of the emission peaks were ascribed to the formation of a π-π complex between TMPyP and dTn. And the quenching of the dTn-enhanced fluorescence by Hg2+ through a synergistic effect occurs due to the heavy atom effect. The binding of Hg2+ to TMPyP plays an important role in the Hg-TMPyP-dT30 ternary complex formation. A TMPyP-dT30-based Hg2+ sensor was developed with a dynamic range of Hg2+ from 5 nM to 100 nM. The detection limit of 1.3 nM was low enough for Hg2+ determination. The sensor also exhibited good selectivity against other metal ions. Experiments for tap water and river water demonstrated that the detection method was applicable for Hg2+ determination in real samples. The Hg2+ sensor based on oligonucleotide dT30-enhanced TMPyP fluorescence was fast and low-cost, presenting a promising platform for practical Hg2+ determination.

Duplex-specific nuclease-based electrochemical biosensor for the detection of microRNAs by conversion of homogeneous assay into surface-tethered electrochemical analysis.

We proposed a simple and sensitive strategy for the detection of microRNAs (miRNAs) by converting homogeneous assay into surface-tethered electrochemical analysis. Specifically, the biotinylated detection probes (biotin-DNA-biotin) can trigger the in-situ assembly of tetrameric streptavidin (SA) proteins on an electrode surface via the SA-biotin interactions. The (SA-biotin-DNA-biotin)n assemblies electrically insulated the electrode interface, thereby blocking the electron transfer of [Fe(CN)6]3-/4-. When the probe was hybridized with the target miRNA, it would be cleaved into small fragments (denoted as biotin-DNA) by duplex-specific nuclease (DSN). The released target miRNA can enter into the next hybridization-enzymolysis cycle, thus leading to the generation of considerable amounts of biotin-DNA fragments. The released biotin-DNA competed with the detection probe to bind SA, thus limiting the in-situ formation of (SA-biotin-DNA-biotin)n assemblies. The surface-tethered electrochemical analysis by the dual signal amplification of DSN and (SA-biotin-DNA-biotin)n assemblies has been used for the determination of miRNAs in cell lysate with a satisfactory result. The method showed a detection limit down to 10 aM. The "one-step" immobilization-free strategy can be used to design novel biosensors for the detection of other biomarkers.

Magnetic bead-based electrochemical and colorimetric assays of circulating tumor cells with boronic acid derivatives as the recognition elements and signal probes.

Simple, sensitive and rapid detection of circulating tumor cells (CTCs) is of great importance for early diagnosis and therapy of cancers. Overexpression of sugar units on cell surface is related to the phenotypes of many cancers. Based on the boronate ester interaction, we reported the electrochemical and colorimetric detection of CTCs with high simplicity and sensitivity. Specifically, ferroceneboronic acid (FcBA) can be measured by differential pulse voltammetry and 4-mercaptophenylboronic acid (MPBA) can induce the aggregation and color change of gold nanoparticles (AuNPs). CTCs captured by the aptamer-modified magnetic beads (Apt-MBs) can sequestrate FcBA or MPBA molecules by the formation of boronate ester bonds, thus leading to the decrease in the electrochemical signal of FcBA or preventing the MPBA-triggered aggregation of AuNPs. Due to the overexpression of sugar groups on the surface of CTCs, the amplification-free methods exhibited high sensitivity and obviated the use of additional antibody or aptamer for the recognition of captured cells. With MCF-7 cancer cell as the model, 50 cells can be readily determined by the electrochemical and colorimetric methods. The proposed strategy is valuable for probing of cell glycosylation and designing of novel sensing devices for detection of sugar-containing biological macromolecules and cells.

1-(3,4-Dihy-droxy-phen-yl)hexan-1-one.

In the title compound, C(12)H(16)O(3), a fully extened hexyl carbon chain is attached to a benzene ring; the mean planes formed by the atoms in the benzene ring and the hexa-none are inclined at an angle 8.5 (2)° with respect to each other. In the crystal, inter-molecular O-H⋯O hydrogen bonds join the mol-ecules into an infinite sheet.

Recurrence in patients following curative resection of early gastric carcinoma.

OBJECTIVE: Post-gastrectomy recurrences of early gastric cancer occur in a few cases. We investigated the outcome of early gastric cancer patients treated surgically, with special respect to the risk factor(s) for tumor recurrence. PATIENTS AND METHODS: A total of 308 patients with mono-foci early gastric cancer underwent curative surgical resection. Clinicopathological variables and tumor recurrence patterns were analyzed retrospectively. RESULTS: Recurrence was observed in 30 out of 245 patients (12.24%) who had completed follow-up. The median interval from surgery to diagnosis of recurrence was 28 (range 3-188) months. Hematogenous recurrence (3.27%) was twice as frequent as peritoneal recurrence (1.63%). Gastric stump cancer occurred in 9 patients (3.67%), anastomotic recurrence in 7 patients (2.86%) and lymphatic recurrence in 4 patients (1.63%). Older patients (> or =60 years old) had a more frequent recurrence rate than younger patients (P < 0.05). Multivariate analyses identified lymph node metastasis and depth of invasion as risk factors of recurrence. All the patients with a positive family history of cancer got recurrence within 3 years after surgery. CONCLUSIONS: Early gastric cancer patients, who were elderly, had lymphatic and submucosal involvement, and patients with a positive family history of cancer, tended to have a greater risk of recurrence.

Fabrication of multifunctional monometallic nanohybrids for reactive oxygen species-mediated cell apoptosis and enhanced fluorescence cell imaging.

Novel fluorescent monometallic Ag nanohybrids (Ag NHs) have been synthesized via polycytosine-mediated biomineralization on Ag nanoparticles (Ag NPs). Thiolated polycytosine dC12 was anchored on the Ag NPs, followed by dC12-templated synthesis of the Ag nanoclusters (Ag NCs). The Ag NHs exhibited strong fluorescence emission and improved resistance to dissolved oxygen in solution as compared to the Ag NCs. As an efficient therapeutic agent, the delivery of aptamer-functionalized Ag NHs into target cells induced reactive oxygen species (ROS) generation and cell apoptosis. The ROS-mediated apoptotic effect of the Ag NHs was stronger than that of the Ag NCs. For cell imaging, the target cells treated with aptamer-functionalized Ag NHs exhibited a higher fluorescence brightness than those treated with Ag NCs. Due to the fluorescence quenching of Ag NHs by the intracellularly generated ROS, the Ag NHs served as a fluorescent indicator for real-time monitoring of ROS-mediated cell apoptosis. The In vivo antitumor efficacy of the Ag NHs was also evaluated.

TMPyP Inhibits Amyloid-ß Aggregation and Alleviates Amyloid-Induced Cytotoxicity.

The aggregation or misfolding of amyloid-ß (Aß) is a major pathological hallmark of Alzheimer's disease (AD). The regulation of Aß aggregation is thought to be an effective strategy for AD treatment. The capability of a water-soluble porphyrin, 5,10,15,20-tetrakis(N-methyl-4-pyridyl)porphyrin (TMPyP), to inhibit Aß aggregation and to lower Aß-induced toxicity was demonstrated. As evidenced by surface plasmon resonance and circular dichroism, TMPyP can not only disrupt Aß aggregation but also disassemble the preformed Aß aggregates. The atomic force microscopy imaging proves that TMPyP inhibits the formation of both oligomers and fibrils. Molecular dynamic simulations provide an insight into the interaction between TMPyP and Aß at the molecular level. The half-maximal inhibitory concentrations of TMPyP acting on the oligomers and fibrils were determined to be 0.6 and 0.43 µM, respectively. As a member of porphyrin family, TMPyP is of rather low cytotoxicity, and the cytotoxicity of the Aß aggregates was also relieved upon coincubation with TMPyP. The excellent performance of TMPyP thus makes it a potential drug candidate for AD therapy.

Amplified voltammetric detection of miRNA from serum samples of glioma patients via combination of conducting magnetic microbeads and ferrocene-capped gold nanoparticle/streptavidin conjugates.

MicroRNA (miRNA) plays a key regulatory role in many biological processes, emerging as an important biomarker for a large variety of cancer diseases. Employing gold nanoparticle (AuNP)-coated magnetic microbeads (AuNP-MMBs) as an immobilization matrix for higher loading density of hairpin-structured DNA probes and then ferrocene (Fc)-capped gold nanoparticle/streptavidin conjugates, amplified electrochemical assay of miRNA has been performed. In the presence of target miRNA, a novel assembly was formed via linking biotinylated hairpin DNA probe-covered AuNP-MMBs with Fc-capped gold nanoparticle/streptavidin conjugates and then collected by magnetic electrodes for voltammetric detection. The enlarged surface area, good conductivity of AuNP-MMBs and the multiple Fc tags on the electrode surface ensure high sensitivity of the method. The oxidation peak current of Fc tags is proportional to the concentrations of miRNA ranging from 5 fM to 100 fM, and a detection limit of 0.14 fM was achieved. The proposed assay is highly selective and reproducible, serving as a viable alternative for the detection of miRNA-182 from serum samples of glioma patients.

Dumbbell-shaped metallothionein-templated silver nanoclusters with applications in cell imaging and Hg(2+) sensing.

Metallothionein (MT) is a cysteine-rich, low-molecular-weight protein, which adopts a unique dumbbell-shaped structure with a stable C-terminal α-domain and a reactive N-terminal ß-domain. The specific configuration serves as a unique scaffold for the synthesis of ultra-small fluorescent metal nanoclusters (NCs). For the first time, MT-templated Ag NCs (MT-Ag NCs) with excellent antioxidant capacity and superior biocompatibility were facilely synthesized. The NCs were thoroughly characterized by various techniques. Zn(2+) in the ß-domain was preferentially replaced by Ag(+), which was then reduced by NaBH4 to yield Ag NCs, while Zn(2+) in the α-domain was intactly tetrahedrally-coordinated through thiolate ligands in MT. Fluorescent imaging of HeLa cells was achieved by attaching folic acid (FA) to MT-Ag NCs. Due to the strong binding capacity toward the thiolate ligands in the α-domain, Hg(2+) was assayed via quenching the fluorescence of Ag NCs by an energy transfer process. The methodology described herein may be extended to the synthesis of other metal NCs with potential applications in biosensing and cell imaging.

[Clinical analysis of 38 elderly patients with early double primary cancers].

OBJECTIVE: To study the clinical features and proper treatment of 38 elderly patients with early double primary cancers. METHODS: Thirty-eight elderly patients with early double primary cancers treated from January 1980 to March 2003 were retrospectively reviewed for involved organs, treatment and prognosis. RESULTS: Digestive tract was the most frequently involved, followed by urogenital system and lung. Long-term results of endoscopic mucosal resection (EMR), operation and radiotherapy were superior to other methods. The prognosis of gastrointestinal carcinoma was better than that of prostate carcinoma and hematopoietic system. The operation rate decreased with increasing age. The 5-year survival rates of EMR, operation and radiotherapy were 85.7%, 71.1% and 75.0%, respectively. The medium survival time was 120 months in first cancer and 39 months in the second primary cancer. The 5-year survival rates of the first cancer and second primary cancer were 88.6% and 53.8%. CONCLUSION: Yearly follow-up for elderly patients with endoscopy, beta ultrasonic scan and X-ray contribute to finding of early double primary cancers. Operation is the best treatment of early double primary cancers. Endoscopic mucosal resection is especially suitable for old patients with digestive tract and bladder cancer.

Suppression of CB1 cannabinoid receptor by lentivirus mediated small interfering RNA ameliorates hepatic fibrosis in rats.

It is recognized that endogenous cannabinoids, which signal through CB1 receptors in hepatic stellate cells (HSCs), exert a profibrotic effect on chronic liver diseases. In this study, we suppressed CB1 expression by lentivirus mediated small interfering RNA (CB1-RNAi-LV) and investigated its effect on hepatic fibrosis in vitro and in vivo. Our results demonstrated that CB1-RNAi-LV significantly inhibited CB1 expression, and suppressed proliferation and extracellular matrix production in HSCs. Furthermore, CB1-RNAi-LV ameliorated dimethylnitrosamine induced hepatic fibrosis markedly, which was associated with the decreased expression of mesenchymal cell markers smooth muscle α-actin, vimentin and snail, and the increased expression of epithelial cell marker E-cadherin. The mechanism lies on the blockage of Smad signaling transduction induced by transforming growth factor ß1 and its receptor TGF-ß RII. Our study firstly provides the evidence that CB1-RNAi-LV might ameliorate hepatic fibrosis through the reversal of epithelial-to-mesenchymal transition (EMT), while the CB1 antagonists AM251 had no effect on epithelial-mesenchymal transitions of HSCs. This suggests that CB1 is implicated in hepatic fibrosis and selective suppression of CB1 by small interfering RNA may present a powerful tool for hepatic fibrosis treatment.

A novel tyrosinase biosensor based on biofunctional ZnO nanorod microarrays on the nanocrystalline diamond electrode for detection of phenolic compounds.

A novel tyrosinase biosensor based on biofuncational ZnO nanorod microarrays on the boron-doped nanocrystalline diamond (BDND) substrates was developed. The ZnO nanorod microarrays were firstly deposited on BDND thin film surfaces via a low-temperature solution method, and then ZnO nanorods were functionalized with the mixture of 3-aminopropyltriethoxysilane (APTES) and tetraethoxysilane (TEOS) by a co-condensation approach, then tyrosinase was immobilized to amino-modification ZnO nanorod surfaces by the covalent binding. As-prepared tyrosinase biosensors were used for the detection of phenolic compounds. The tyrosinase-modified BDND electrode gave a linear response range of 1-175, 1-150 and 1-150 microM and sensitivity of 576.2, 339.3 and 287.1 microA mmol(-1) cm(-2) for p-cresol, 4-chlorophenol and phenol, respectively. The low detection limit was estimated to be 0.1, 0.25 and 0.2 microM (s(b)/m=3), respectively. Therefore, the biofunctional ZnO nanorod arrays have potential applications as platforms to immobilize other enzymes and bioactive molecules in biosensors.