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Peng X.,State Engineering Laboratory of Bio Resource Eco Utilization | Peng X.,Northeast Forestry University | Fu H.,Beihang University | Liu R.,State Engineering Laboratory of Bio Resource Eco Utilization | And 9 more authors.
Scanning | Year: 2015

It is important to know the adsorption behavior and assembly structure of human serum albumin (HSA) molecules onto a carbonaceous substrate for further application of carbon nanomaterials in biomedical field. Individual HSA molecules and oligmers (dimer and trimer) adsorbed onto HOPG surface have been imaged by atomic force microscopy (AFM). Individual HSA molecule appeared as an ellipsoid on HOPG surface with average length of 12.6, width of 6.5, and height of 1.9 nm when they were incubated at the physiological condition (pH 7.4). HSA molecules also can form the interconnected chains, uniform network, and monolayer by tuning the initial concentrations and adsorption time. Furthermore, HSA molecules can assemble into quite different network structures and irregular chains at pH of 2, 5, and 10. This study could expand our knowledge of the interactions between protein and carbonaceous surfaces. SCANNING 37:158-164, 2015. © 2015 Wiley Periodicals, Inc. © Wiley Periodicals, Inc. Source


Liu Z.,Northeast Forestry University | Liu Z.,State Engineering Laboratory of Bio Resource Eco Utilization | Xu F.,Northeast Forestry University | Xu F.,State Engineering Laboratory of Bio Resource Eco Utilization | And 6 more authors.
Microscopy Research and Technique | Year: 2016

Recent studies have revealed that water-dispersible colloids play an important role in the transport of nutrients and contaminants in soils. In this study, water-dispersible colloids extracted from saline-alkali soils have been characterized by atomic force microscopy (AFM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and UV absorption spectra. AFM observation indicated that the water-dispersible colloids contain some large plates and many small spherical particles. XRD, XPS, and UV absorption measurement revealed that the water-dispersible colloids are composed of kaolinite, illite, calcite, quartz and humic acid. In addition, UV absorption measurement demonstrated that the humic acids are associated with clay minerals. Water-dispersible colloids in the saline-alkali soils after hydrolyzed polymaleic anhydride treatment and an agricultural soil (nonsaline-alkali soil) were also investigated for comparison. The obtained results implied that the saline-alkali condition facilitates the formation of a large quantity of colloids. The use of AFM combined with spectrometric methods in the present study provides new knowledge on the colloid characteristics of saline-alkali soils. Microsc. Res. Tech. 79:525-531, 2016. © 2016 Wiley Periodicals, Inc. Source


Mu F.,Northeast Forestry University | Mu F.,State Engineering Laboratory of Bio Resource Eco Utilization | Yang L.,Northeast Forestry University | Yang L.,State Engineering Laboratory of Bio Resource Eco Utilization | And 11 more authors.
Molecules | Year: 2012

In the present study, an improved method termed negative-pressure cavitation extraction (NPCE) followed by reverse phase high-performance liquid chromatography (RP-HPLC) was developed for the extraction and quantification of vindoline (VDL), catharanthine (CTR), vincristine (VCR) and vinblastine (VLB) from Catharanthus roseus leaves. The optimized method employed 60-mesh particles, 80% ethanol, a negative pressure of -0.075 MPa, a solid to liquid ratio of 1:20, 30 min of extraction and three extraction cycles. Under these optimized conditions, the extraction yields of VDL, CTR, VCR and VLB are 0.5783, 0.2843, 0.018 and 0.126 mg/g DW, respectively. These extraction yields are equivalent to those from the well-known ultrasonic extraction method and higher than the yields from maceration extraction and heating reflux extraction. Our results suggest that NPCE-RP-HPLC represents an excellent alternative for the extraction and quantification of vinca alkaloids for pilot- and industrial-scale applications. Source


Liu Z.,Northeast Forestry University | Liu Z.,State Engineering Laboratory of Bio Resource Eco Utilization | Zhao L.,Northeast Forestry University | Zhao L.,State Engineering Laboratory of Bio Resource Eco Utilization | And 8 more authors.
Microscopy and Microanalysis | Year: 2013

It is important to know the detailed DNA structure on carbonaceous surfaces for further application of DNA-functionalized carbonaceous materials in diverse research areas. In this study, the topographic and structural characteristics of the separated single DNA molecules and their assembly on highly oriented pyrolytic graphite (HOPG) surfaces have been investigated by atomic force microscopy (AFM). AFM results indicate that both circular and linear DNA molecules tend to form hexagonal patterns along with some unusual structures that include node, protrusion, cruciform, parallel single-stranded DNA (ssDNA), and compact zigzag. Furthermore, parallel ssDNA patterns and their crossed structures have been obtained under high-temperature conditions. Our AFM results reveal that a bare HOPG surface can induce DNA molecules to form various unusual structures. This finding is helpful for understanding the adsorption behavior of DNA on other carbonaceous surfaces such as carbon nanotubes and graphene. In addition, the hexagonal DNA patterns in this study are similar to those formed on the alkylamine-modified HOPG surface, which implies that a bare HOPG, without any chemical modification, has a strong ability to align biomolecules. This study could expand our knowledge of the diversities of DNA structures and the aligning ability of carbonaceous surfaces. Copyright © Microscopy Society of America 2013 Â. Source


Liu Z.,State Engineering Laboratory of Bio Resource Eco Utilization | Liu Z.,Northeast Forestry University | Liu R.,State Engineering Laboratory of Bio Resource Eco Utilization | Liu R.,Northeast Forestry University | And 6 more authors.
Biochemical and Biophysical Research Communications | Year: 2015

Interaction between long DNA molecules and activated cisplatin is believed to be crucial to anticancer activity. However, the exact structural changes of long DNA molecules induced by cisplatin are still not very clear. In this study, structural changes of long linear double-stranded DNA (dsDNA) and short single-stranded DNA (ssDNA) induced by activated cisplatin have been investigated by atomic force microscopy (AFM). The results indicated that long DNA molecules gradually formed network structures, beads-on-string structures and their large aggregates. Electrostatic and coordination interactions were considered as the main driving forces producing these novel structures. An interesting finding in this study is the beads-on-string structures. Moreover, it is worth noting that the beads-on-string structures were linked into the networks, which can be ascribed to the strong DNA-DNA interactions. This study expands our knowledge of the interactions between DNA molecules and cisplatin. © 2015 Elsevier Inc. All rights reserved. Source

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