A novel photoelectrochemical self-screening aptamer biosensor based on CAU-17-derived Bi2WO6/Bi2S3 for rapid detection of quorum sensing signal molecules.

Quorum sensing signal molecule is an important biomarker released by some microorganisms, which can regulate the adhesion and aggregation of marine microorganisms on the surface of engineering facilities. Thus, it is significant to exploit a convenient method that can effectively monitor the formation and development of marine biofouling. In this work, an advanced photoelectrochemical (PEC) aptamer biosensing platform was established and firstly applied for the rapid and ultrasensitive determination of N-(3-Oxodecanoyl)-l-homoserine lactone (3-O-C10-HL) released from marine fouling microorganism Ponticoccus sp. PD-2. The visible-light-driven Bi2WO6/Bi2S3 heterojunction derived from metal-organic frameworks (MOFs) CAU-17 and self-screened aptamer were employed as the photoactive materials and bioidentification elements, respectively. Appropriate amount of MoS2 quantum dots (QDs) conjugated with single-stranded DNA were introduced by hybridization to enhance the photocurrent response of the PEC biosensor. The self-screening aptamer can specifically recognize 3-O-C10-HL, accompanied by increasing the steric hindrance and forcing MoS2 QDs to leave the electrode surface, resulting in an obvious reduction of photocurrent and achieving a dual-inhibition signal amplification effect. Under the optimized conditions, the photocurrent response of PEC aptasensor was linear with 3-O-C10-HL concentration from 1 nM to 10 µM, and the detection limit was as low as 0.26 nM. The detection strategy also showed a high reproducibility, superior specificity and good stability. This work not only provides a simple, rapid and ultrasensitive PEC aptamer biosensing strategy for monitoring quorum sensing signal molecules in marine biofouling, but also broadens the application of MOFs-based heterojunctions in PEC sensors.

Corrosion of Q235 carbon steel induced by sulfate-reducing bacteria in groundwater: corrosion behavior, corrosion product, and microbial community structure.

Microbiologically influenced corrosion (MIC) is one of the reasons leading to the service failure of pipelines buried in the soil. In this work, the effect of sulfate-reducing bacteria (SRB) on the corrosion behavior of Q235 carbon steel in groundwater was investigated by electrochemical methods, surface analysis, and biological analysis. The results show that SRB utilizes iron as electron donor to sustain the vital activities of organic carbon-starved groundwater during the 14-day experimental period. The microbial community composition analysis at the genus level demonstrate that the diversity and richness decrease after corrosion, and the dominant SRB species has changed from Desulfovibrio to Desulfosporosinus. Moreover, the impedance of the carbon steel in the presence of biofilm was 1 order of magnitude higher than that of other periods in the electrochemical test, indicating that the biofilm and formed ferrous sulfide layer impeded the occurrence of corrosion. Although the 3D topography indicated that the surface of carbon steel was more uneven and pits were increased in the presence of SRB, the average weight loss (0.0396 ± 0.0050 g) was much higher than that without SRB (0.0139 ± 0.0007 g). These results implied that the growth of SRB makes the corrosion process of Q235 carbon steel more complicated.

The Yellow Sea green tide: A risk of macroalgae invasion.

Large scale green tides have bloomed successively in the Yellow Sea since 2007. The floating ecotype of Ulva prolifera, which is responsible for the environmental disaster, drifted a long distance during the blooming time and was exotic to the coastal area. The Yellow Sea green tide can be a potential source to incur bio-invasion. In this study, the distribution pattern and propagule pressure of the floating ecotype was investigated along the Qingdao coastline, which was seriously impacted by the green tide. Two out of 661 attached Ulva specimens collected in different seasons were identified as the floating ecotype by molecular markers, indicating that a few individuals of the floating ecotype had settled down, and their attached population could have spontaneously established. In seawater and sediments, the proportion of the floating ecotype in Ulva propagules reached up to 32% and 69% respectively when the floating algae was accumulating on seashore, which was a great propagule pressure to the local ecosystem. Results of the field test indicated that the available resources and the competition between the floating ecotype and the local Ulva species might be the main restrictions for settlement. Though the current scale of the established population is still small, the risk of biological invasion by the floating ecotype exists and it deserves more attention.

CuZn dendritic alloys: their template-free electrochemical preparation and morphology-dependent wettability.

In this paper, we report a preparation of CuZn dendritic microstructures through a tunable template-free electrochemical approach. By simply tunning the applied depositing current, the morphology of the product can be well controlled. The growth mechanism of CuZn dendritic alloys was also verified. The experimental results suggest that the growth of the grass-like structures obtained at 5 mA is driven by diffusion limited aggregation, while the driving force of the formation of CuZn dendrites obtained at 10 mA and 15 mA is gas bubbling worked as the dynamic template. The contact angle test shows the modified CuZn dendritic products possess superhydrophobic property. Additionally, through annealing of CuZn alloys in argon as the protective gas, derivative Cu/ZnO composite materials can be produced.

New development and application of ultrasound targeted microbubble destruction in gene therapy and drug delivery.

Ultrasound is a common used technique for clinical imaging. In recent years, with the advances in preparation technology of microbubbles and the innovations in ultrasound imaging, ultrasound is no longer confined to detection of tissue perfusion, but extends to specific ultrasound molecular imaging and target therapy gradually. With the development of research, ultrasound molecular imaging and target therapy have made great progresses. Targeted microbubbles for molecular imaging are achieved by binding target molecules, specific antibody or ligand to the surface of microbubbles to obtain specific imaging by attaching to target tissues. Meanwhile, it can also achieve targeting gene therapy or drug delivery by ultrasound targeted microbubble destruction (UTMD) mediating genes or drugs to specific target sites. UTMD has a number of advantages, such as target-specific, highly effective, non-invasivity, relatively low-cost and no radiation, and has broad application prospects, which is regarded as one hot spot in medical studies. We reviewed the new development and application of UTMD in gene therapy and drug delivery in this paper. With further development of technology and research, the gene or drug delivery system and related methods will be widely used in application and researches.

Optimization and apoptosis induction by RNAi with UTMD technology in vitro.

Apoptosis induction by short hairpin RNA (shRNA) expression vectors may be an efficient and promising strategy for cancer gene therapy. Ultrasound-targeted microbubble destruction (UTMD) is an appealing technique; however, there few data are available to demonstrate the feasibility and to optimize the methodology for this technology. The aim of this study was to optimize this technique and to elucidate the effects on gene inhibition and apoptosis induction in vitro. Human cervical cancer cell lines were obtained and cultured.shRNA vectors were constructed, and the UTMD technique was examined to determine whether or not it was suitable for shRNA transfection into cells. Cells were then examined using flow cytometry. The results revealed that the optimal irradiation parameters obtained higher transfection efficiency and did not affect the integrity of plasmid DNA. We concluded that survivin downregulation with shRNA expression vectors, mediated by the optimal UTMD parameters, markedly induced cell apoptosis and caused cell cycle arrest, laying a foundation for further investigation of this cancer therapy.

One-dimensional ferromagnetic dendritic iron wire array growth by facile electrochemical deposition.

One-dimensional ferromagnetic iron dendritic wire array film is prepared by facile electrodeposition. The space hindrance effect caused by neighbouring crystals resists the free growth directions parallel to the substrate, which is considered as a possible growth mechanism of one-dimensional morphology. Dendritic iron wire can be transformed into α-Fe(2)O(3) without destroying the dendritic morphology by thermal oxidation.

Augmentation of transgenic expression by ultrasound­mediated liposome microbubble destruction.

Non-invasive, efficient and tissue-specific transgenic technologies could be valuable in gene therapy. Although non-viral carriers may be safer and cheaper, they have a much lower transfection efficiency than viral gene carriers. The present study was designed to test the transgenic expression and safety of red fluorescent protein (RFP) in HeLa cells in vitro and in transplanted tumors of nude mice in vivo under ultrasound-mediated liposome microbubble destruction (UMLMD) conditions. Plasmids containing RFP were gently mixed with liposome microbubbles (LMs). The mixture was added to HeLa cells or injected into BALB/c mice by the tail vein under various ultrasound exposure and LM parameters, and then the transfection efficiencies were examined. The results in vivo and in vitro demonstrated that, following a comparison of the plasmid group, the ultrasound + plasmid group and the LM + plasmid group, UMLMD significantly increased the transgenic expression (P<0.01) without causing any apparent detrimental effect. From the study, we concluded that UMLMD could be a non-invasive, effective and promising non-viral technique for gene therapy and transgenic research.

Ultrasound- and liposome microbubble-mediated targeted gene transfer to cardiomyocytes in vivo accompanied by polyethylenimine.

OBJECTIVES: Gene transfer to cardiomyocytes in vivo has received much research attention in the last decade but remains a substantial hurdle. Gene transfer using ultrasound-targeted microbubble destruction is a promising tool for gene therapy. Little data have shown the feasibility and optimization of this method for primary myocardial disease. In this study, we sought to determine the feasibility and efficiency of in vivo gene transfer to the myocardium mediated by ultrasound-targeted microbubble destruction accompanied by polyethylenimine. METHODS: Three plasmids (luciferase reporter, red fluorescent protein reporter, and enhanced green fluorescent protein reporter) were used in this study. The ultrasound parameters were also optimized. A solution containing phosphate-buffered saline, a plasmid, plasmid complex, or polyethylenimine/plasmid, and liposome microbubbles was injected via a tail vein with (study) or without (control) transthoracic ultrasound irradiation. The efficiency of reporter gene transfer was determined by detection of luciferase activity or microscopy, and histologic investigations of the tissue specimens were performed. RESULTS: Ultrasound-targeted microbubble destruction significantly increased luciferase activity in vivo compared to plasmids and microbubbles alone (P < .001). More importantly, the increase in transgene expression was significantly related to ultrasound-targeted microbubble destruction in the presence of polyethylenimine (P < .001). In addition, fluorescein expression was present in all sections that received ultrasound-targeted microbubble destruction. The fluorescent reporter genes and luciferase plasmid all had similar results. Regardless of ultrasound exposure, expression in other organs was close to a background level except for the liver and lung. Hematoxylin-eosin staining showed no notable myocardial injury or death in control and treated mice. CONCLUSIONS: An atraumatic targeted gene delivery technique based on ultrasound-targeted microbubble destruction and polyethylenimine has been developed to transfect cardiomyocytes in vivo. If a suitable target gene is added, the novel technique could be highly effective in many kinds of heart disease.

Enhancing microRNA transfection to inhibit survivin gene expression and induce apoptosis: could it be mediated by a novel combination of sonoporation and polyethylenimine?

Apoptosis is a physiologically essential mechanism of cell and plays an important role in reducing the development and progression of tumors. The appealing strategy for cancer therapy is to target the lesions that induce apoptosis in cancer cells. Survivin, the smallest member of the mammalian inhibitors of the apoptosis protein family, is upregulated in various malignancies to protect cells from apoptosis. Survivin knockdown could induce cancer cell apoptosis and inhibit tumor-angiogenesis. Survivin expression would be silenced by microRNA (miRNA)-mediated RNA interference. However, noninvasive and tissue-specific gene delivery techniques remain absent recently and the utilizations of miRNA expression vectors have been limited by inefficient delivery technique, especially in vivo. On the other hand, safe and promising technologies of gene transfection would be valuable in clinical gene therapy. Successful treatment of gene transfer method would lead to a new and readily available approach in the anticancer research. Sonoporation is an alternative technique of gene delivery that uses ultrasound targeted microbubble destruction to create pores in the cell membrane. Based on our previous studies, in this article, we postulated that the transfection of miRNA could be mediated by the combination of sonoporation and polyethylenimine (PEI) which was one of the most effective poly-cationic gene vectors and enhance the endocytosis of plasmids DNA and hypothesized that the gene silencing and apoptosis induction with miRNA targeting human Survivin would be improved by this novel technique. In our opinion, this novel combination of sonoporation and PEI could enhance targeted gene delivery effectively and might be a feasible, novel candidate for gene therapy.

Targeted gene delivery in tumor xenografts by the combination of ultrasound-targeted microbubble destruction and polyethylenimine to inhibit survivin gene expression and induce apoptosis.

BACKGROUND: Noninvasive and tissue-specific technologies of gene transfection would be valuable in clinical gene therapy. This present study was designed to determine whether it could enhance gene transfection in vivo by the combination of ultrasound-targeted microbubble destruction (UTMD) with polyethylenimine (PEI) in tumor xenografts, and illuminate the effects of gene silencing and apoptosis induction with short hairpin RNA (shRNA) interference therapy targeting human survivin by this novel technique. METHODS: Two different expression vectors (pCMV-LUC and pSIREN) were incubated with PEI to prepare cationic complexes (PEI/DNA) and confirmed by the gel retardation assay. Human cervical carcinoma (Hela) tumors were planted subcutaneously in both flanks of nude mice. Tumor-bearing mice were administered by tail vein with PBS, plasmid, plasmid and SonoVue microbubble, PEI/DNA and SonoVue microbubble. One tumor was exposed to ultrasound irradiation, while the other served as control. The feasibility of targeted delivery and tissue specificity facilitated by UTMD and PEI were investigated. Moreover, immunohistochemistry analyses about gene silencing and apoptosis induction were detected. RESULTS: Electrophoresis experiment revealed that PEI could condense DNA efficiently. The application of UTMD significantly increases the tissue transfection. Both expression vectors showed that gene expressions were present in all sections of tumors that received ultrasound exposure but not in control tumors. More importantly, the increases in transgene expression were related to UTMD with the presence of PEI significantly. Silencing of the survivin gene could induce apoptosis effectively by downregulating survivin and bcl-2 expression, also cause up-regulation of bax and caspase-3 expression. CONCLUSIONS: This noninvasive, novel combination of UTMD with PEI could enhance targeted gene delivery and gene expression in tumor xenografts at intravenous administration effectively without causing any apparently adverse effect, and might be a promising candidate for gene therapy. Silencing of survivin gene expression with shRNA could be facilitated by this non-viral technique, and lead to significant cell apoptosis.

[Experimental study of tissue-engineered skin loaded with keratinocyte growth factor nanocapsules for skin defect].

OBJECTIVE: To study the effect of tissue-engineered skin loaded with keratinocyte growth factor (KGF) nanocapsules for skin defect on athymic mice. METHODS: The acellular dermal matrix (ADM) loaded with KGF-ADM was constructed by means of phacoemulsification solvent evaporation and low temperature drying. The human epidermal stem cells and fibroblasts were captured and identified, then cultivated on the surface of the KGF-ADM. The cell growth was observed. The tissue-engineered skin without KGF was used as sham group. The autogenous skin graft was used as control group. 2 and 6 weeks after the skin was transplanted to the back of athymic mice, the contraction and histological healing of the transplanted skins were observed respectively. Then the immunofluorescence examination with anti-human K10-FITC and beta1-integrin-Cy3 were applied to detect the origin, growth and differentiation of epidermal and dermal cells in tissue-engineered skin. RESULTS: The epidermal stem cells grew well and attached tightly on KGF-ADM. There were small round stem cells and polygonal terminally-differentiated cells, which appeared a partly cloning growth and a tendency of merging. The tissue-engineered skin with KGF nanocapsules gained better result in repairing the skin defects as compared with the blank group and the control group 2 and 6 weeks after transplantation. The regenerative skin cells could connect and mix closely with the athymic mouse skin cells on the border of skin defect. Meanwhile, the regenerative skin existed some contraction. The histological observation with HE staining showed that the regenerative skin possessed intact epidermis with several cell layers and normal keratose stratum, among which there were still some beta1-integrin (+) cells which represented epidermal stem cells or transient amplifying cells when they were tested by immunofluorescence after 6 weeks of transplantation. CONCLUSIONS: The tissue-engineered skin loaded with KGF nanocapsules had a better result in repairing athymic mice skin defects than common tissue-engineered skin without KGF nanocapsules or skin auto-graft.

A comparative study on two kinds of surgical procedures of penile corpora cavernosa augmentation.

OBJECTIVE: Penile augmentation surgery is still a controversial issue because of the uncertain indication, the possibility of severe complications and a variety of surgical techniques. The purpose of this study is to provide two surgical procedures of penile corpora cavernosa augmentation and to investigate its effect by implanting autogenous saphenous vein grafts or expanded polytetrafluoroethylene (ePTFE) vessel patches. METHODS: Between January 2001 and December 2005, 20 patients underwent surgeries in which bilateral longitudinal incisions were placed on the tunica albuginea and the penile corpora cavernosa were extended by means of implantation of saphenous grafts or PTFE artificial vessel patches. The patients included in this study presented either with congenital idiopathic micropenis or normal penile length and perimeter (dysmorphophobia). Before the operation, the penile length and perimeter in the flaccid and erectile states were as follows: flaccid length 2.5-7.5 cm and flaccid perimeter 3.0-7.5 cm; erectile length 4.9-10.5 cm and erectile perimeter 4.5-10.0 cm. RESULTS: Immediately after surgery, the penile corpus circumferential measurements (on table), showed remarkable increases which were 1.0-2.3 cm and 1.5-3.0 cm in the flaccid and erectile states, respectively; then, at 12 months to 5 years' follow-up, these girth gains had reduced by 0.5-1 cm in some cases. All cases in the two groups obtained satisfactory surgical results with satisfactory erection and no serious complications, such as infection and fistula. In 20 cases, 17 married cases resumed regular and satisfactory sexual activities 1 month after the operation without any functional limitation. CONCLUSION: The two kinds of surgical procedures for augmenting penile corpora cavernosa were proved to be effective and reliable, with few complications. Both saphenous grafts and ePTFE artificial vessel patches are excellent materials for reconstructing the tunica albuginea. These augmenting phalloplasties can not only be used for patients with micropenis, but also applied to satisfy the cosmetic and functional requests of patients with normal penile length and perimeter. However, the long-term outcomes of these surgical procedures need a further, detailed follow-up study.

Morphological transformation of Co(OH)2 microspheres from solid to flowerlike hollow core-shell structures.

We report, for the first time, a detailed investigation into the formation of highly uniform, 3D, flowerlike, hollow, spherical architectures of cobalt hydroxide through a facile solvothermal process. Various controlling parameters were examined, such as water content in starting materials, reaction time, cobalt(II) precursor concentration, and reaction temperature. On the basis of the experimental results, the formation mechanism of these flowerlike cobalt hydroxide hollow spheres involves aggregation of cobalt hydroxide building clusters into solid spheres and hollowing effect through subsequent dissolution, diffusion, and re-deposition of the smaller crystallites under the surface layer driven by an Ostwald ripening process. Metallic cobalt hollow spheres have also been obtained by thermal decomposition of cobalt hydroxide flowers in a mixed gas of Ar+4 % H(2) at 400 degrees C. The morphology and composition of the products were characterized by X-ray diffraction, field-emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, and (high resolution) transmission electron microscopy.

Synthesis and magnetic properties of one-dimensional zinc nickel oxide solid solution.

A novel facile method has been demonstrated for large-scale synthesis of zinc-oxide-based one-dimensional solid solution with a series percentage of nickel dopant. The obtained Zn1-xNixO nanorods were characterized by X-ray diffraction, transmission electron microscopy, selected area electron diffraction, and energy dispersed X-ray spectroscopy. The result shows that the obtained Zn1-xNixO nanorods are single crystalline with the Ni2+ dopants occupying tetrahedral Zn2+ cation sites of wurtzite ZnO. Moreover, the Zn1-xNixO nanorods exhibit robust high-Curie-temperature (TC) ferromagnetism at 300 K.