128 research outputs found

    Enumerasi Total Populasi Mikroba Tanah Gambut Di Teluk Meranti Kabupaten Riau

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    Teluk Meranti is one of the peatland area in Riau province. Most of these lands have beenchanged into palm oil plantation, timber plantation, agricultural area and settlement. Theaim of this research was to analyze the impact of land use changes on soil physical-chemical characteristics and microbial cell number. Soil samples were taken from eightdifferent locations, namely primary forest as control, secondary forest, rubber plantation(15 monthsyears old), rubber forest (40-60 years old), palm oil plantation (7-8 years old),acacia plantation (2-3 years old), corn field, and cassava field. Microbial cell number wasdetermined by spread plate method, employing appropriate media for the growth ofbacteria, fungi and actinomycetes. The results showed that the soil humidity, soiltemperature, percentage of soil dry weight, water content, soil bulk density and pH rangedfrom 29,63-55,88%, 27-31,5 o C, 14,9-35,5%, 64,9-85,1%, 0,16-0,39 g/cm 3 and 3,63-4,00,respectively. The copiotrophic bacterial cell number ranged from 0,6x10 5 -1,8x10 5 CFU/gsoil where the highest population was at the palm oil plantation,whereas the oligotrophicbacterial cell number ranged from 0,5x10 5 -1,4x10 5 CFU/g soil where the highest populationwas at the palm oil plantation. The population of fungi ranged from 0,4x10 5 -1,0x10 5 CFU/gsoil where the highest population was at the corn field. The population of actinomycetesranged from 0,4x10 5 -10,7x10 5 CFU/g soil where the highest population was at the palm oilplantation. Land use changes caused microbial cell number increased. The results indicatedthat land use changes influenced the microbial cell numbers

    Synthesis of pH-Responsive Inorganic Janus Nanoparticles and Experimental Investigation of the Stability of Their Pickering Emulsions

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    Pickering emulsions exhibit outstanding stability, especially those prepared with Janus particles, whose desorption energy is expected to be up to 3-fold greater than emulsions of homogeneous particles from theoretical calculations. To the best of our knowledge, however, there remains no experimental proof of this behavior in practice. In this study, inorganic Janus nanoparticles were fabricated by regioselective modification of the separate side of SiO<sub>2</sub> nanoparticles with a judiciously selected mixture of trimethoxysilylpropyldiethylenetriamine and <i>n</i>-octyltrimethoxysilane. Janus nanoparticles demonstrated excellent interfacial activity, forming Pickering emulsions with oil phases at oil–water interfacial tensions ranging from 6.6–52.8 mN m<sup>–1</sup>. Furthermore, as the interface of the Janus nanoparticles was regionally functionalized with −NH<sub>2</sub> groups, phase inversion could be realized by tuning pH. This is the first example for the Pickering emulsions stabilized with inorganic Janus particles. Importantly, based on the results of centrifugation experiment, the desorption energy of Janus nanoparticles at the interface was 3.2 times larger than that of homogeneous nanoparticles, which is in accordance with the result from theoretical calculations. These experimental results will substantially enrich our understanding of Janus nanoparticle Pickering emulsions and their interfacial assembly behavior

    Aboveground biomass in pure soils

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    Aboveground biomass in pure soil

    From Nonporous to Porous Doubly-Pillared-Layer Framework: Control over Interpenetration via Shape Alteration of Layer Apertures

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    By introducing an amino substituent group on the dicarboxylate ligand, a porous doubly pillared-layer framework [Co<sub>2</sub>(abdc)<sub>2</sub>(bpy)<sub>2</sub>]·8DMF (<b>2</b>; abdc = 2-amino-1,4-benzene dicarboxylate, bpy = 4,4′-bipyridine) has been obtained, which represents a shape/size modulation of the layer apertures to control over 2-fold interpenetration arising from the nonporous structure of [Co<sub>2</sub>(bdc)<sub>2</sub>(bpy)<sub>2</sub>] (<b>1</b>; bdc = 1,4-benzene dicarboxylate). The bulk-phase purity, framework robustness and permanent porosity of <b>2</b> have been confirmed by powder X-ray diffraction, thermogravimetric analysis, and gas adsorption isotherms

    Cell Penetrating Peptide-Based Redox-Sensitive Vaccine Delivery System for Subcutaneous Vaccination

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    In immunotherapy, induction of potent cellular immunity by vaccination is essential to treat intracellular infectious diseases and tumors. In this work, we designed a new synthetic peptide carrier, Cys-Trp-Trp-Arg<sub>8</sub>-Cys-Arg<sub>8</sub>-Cys-Arg<sub>8</sub>-Cys, for vaccine delivery by integrating a redox-responsive disulfide bond cross-linking and cell-penetrating peptide arginine octamer. The carrier peptide bound to the antigen protein ovalbumin (OVA) via electrostatic self-assembly to form peptide/OVA nanocomposites. Then, the spontaneous oxidization of the thiols of the cysteine residues induced interpeptide disulfide bond cross-linking to construct denser peptide/OVA condensates. The cell-penetrating peptides incorporated in the carrier peptide could increase antigen uptake by antigen presenting cells. After being internalized by antigen presenting cells, the antigen could be rapidly released in cytoplasm along with degradation of the disulfide bonds by intracellular glutathione, which could promote potent CD8<sup>+</sup> T cell immunity. The cross-linked peptide/OVA condensates were used for subcutaneous vaccination. The results showed that the peptide carrier mediated potent antigen-specific immune response by significantly increasing IgG titer; splenocyte proliferation; the secretion level of cytokines INF-γ, IL-12, IL-4, and IL-10; immune memory function, and the activation and maturation of dendritic cells. From the results, the low-molecular weight vaccine-condensing peptide with definite chemical composition could be developed as a novel class of vaccine delivery systems

    Tumor-Penetrating Peptide-Functionalized Redox-Responsive Hyperbranched Poly(amido amine) Delivering siRNA for Lung Cancer Therapy

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    Biosafety and the targeting ability of gene delivery systems are critical aspects for gene therapy of cancer. In this study, we report the synthesis and use of redox-responsive poly­(amido amine) (PAA) with good biocompatibility and biodegradation as a gene carrier material. A tumor-specific tissue penetration peptide, internalizing-RGD (iRGD) was then conjugated to PAA with an amidation reaction. In experiments using H1299 cells, PAA-iRGD was found to have a lower cytotoxicity and higher cellular uptake efficiency compared to PAA. An siRNA, specific to epidermal growth factor receptor (EGFR) that is overexpressed on the lung cancer cell surface and often targeted in lung cancer treatment, was designed to silence EGFR (i.e., siEGFR) for delivery by the gene carrier PAA-iRGD. <i>EGFR</i> gene silencing, apoptosis, antiproliferation, and antitumor effects of PAA-iRGD/siEGFR were evaluated <i>in vitro</i> and <i>in vivo</i>. PAA-iRGD/siEGFR displayed a much higher gene silencing ability compared to PAA and polyethylenimine (25 kDa), significantly inhibited the proliferation and migration of H1299 cells, and elicited significant cell apoptosis. Moreover, intravenously injected PAA-iRGD/siEGFR inhibited lung tumor growth <i>in vivo</i>. These results suggest that PAA-iRGD with good biocompatibility, biodegradation, and targeting ability could be a promising gene delivery system for gene therapy of cancers

    Combined Chemo-photothermal Antitumor Therapy Using Molybdenum Disulfide Modified with Hyperbranched Polyglycidyl

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    In the treatment of cancers, molybdenum disulfide (MoS<sub>2</sub>) has shown great potential as a photoabsorbing agent in photothermal therapy and also as an antitumor drug delivery system in chemotherapy. However, the poor dispersibility and stability of MoS<sub>2</sub> in aqueous solutions limit its applications in cancer therapy. To overcome the shortcomings, MoS<sub>2</sub> was modified mainly by surface adsorption of linear polymers, such as chitosan and poly­(ethylene glycol). As reported, the linear polymers could be more rapidly cleared from blood circulation than their branched counterparts. Herein, we developed hyperbranched polyglycidyl (HPG)-modified MoS<sub>2</sub> (MoS<sub>2</sub>–HPG) by absorbing HPG on the MoS<sub>2</sub> surface. The MoS<sub>2</sub>–HPG as a novel photoabsorbing agent was also used as a nanoscaled carrier to load antitumor drug doxorubicin hydrochloride (DOX) (MoS<sub>2</sub>–HPG–DOX) for combined chemo-photothermal therapy. The physicochemical and photothermal properties of MoS<sub>2</sub>–HPG were measured, and the results indicate that MoS<sub>2</sub>–HPG had good dispersion and stability in aqueous solutions and also high photothermal conversion efficiency. MoS<sub>2</sub>–HPG displayed good biocompatibility in hemocompatibility and cytotoxicity evaluations in vitro. Furthermore, the combined chemo-photothermal therapy using MoS<sub>2</sub>–HPG–DOX demonstrated better anticancer effect than the individual chemotherapy or photothermal therapy alone. From the results, MoS<sub>2</sub>–HPG with combined chemo-photothermal therapy could be developed as a promising therapeutic formulation for clinical cancer treatment

    Polyethylenimine-Induced Alterations of Red Blood Cells and Their Recognition by the Complement System and Macrophages

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    In practical applications, biomedical materials introduced in vivo may interact with various host cells and/or biomacromolecules and alter their physiological characteristics. Biomaterial-altered cells and/or biomacromolecules may be recognized as “non-self” by the host immune system and may consequently cause further immune responses. In the present work, the gene carrier material branched polyethylenimine (1.8 kDa) (BPEI-1.8k) induced a series of alterations of human red blood cells (RBCs), such as a morphological transition from biconcave disks to spheroechinocytes, vesiculation, a size decrease, a change in surface charge from negative to positive, a cell density reduction, membrane oxidation, and PS externalization. Furthermore, BPEI-1.8k-treated RBCs caused autologous complement activation and were recognized by autologous macrophages. This implies that the biomedical material BPEI-1.8k changed the identity of the RBCs, leading to their recognition by the autologous immune system. This study provides novel insights for the biocompatibility evaluation and clinical application of biomedical materials

    Blood Compatibility Evaluations of Fluorescent Carbon Dots

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    Because of their unique advantages, fluorescent carbon dots are gaining popularity in various biomedical applications. For these applications, good biosafety is a prerequisite for their use in vivo. Studies have reported the preliminary biocompatibility evaluations of fluorescent carbon dots (mainly cytotoxicity); however, to date, little information is available about their hemocompatibility, which could impede their development from laboratory to bedside. In this work, we evaluated the hemocompatibility of fluorescent carbon dots, which we prepared by hydrothermal carbonization of α-cyclodextrin. The effects of the carbon dots on the structure and function of key blood components were investigated at cellular and molecular levels. In particular, we considered the morphology and lysis of human red blood cells, the structure and conformation of the plasma protein fibrinogen, the complement activation, platelet activation, and in vitro and in vivo blood coagulation. We found that the carbon dots have obvious concentration-dependent effects on the blood components. Overall, concentrations of the fluorescent carbon dots at ≤0.1 mg/mL had few adverse effects on the blood components, but at higher doses, the carbon dots impair the structure and function of the blood components, causing morphological disruptions and lysis of red blood cells, interference in the local microenvironments of fibrinogen, activation of the complement system, and disturbances in the plasma and whole blood coagulation function in vitro. However, the carbon dots tend to activate platelets only at low concentrations. Intravenous administration of the carbon dots at doses up to 50 mg/kg did not impair the blood coagulation function. These results provide valuable information for the clinical application of fluorescent carbon dots