Abstract: In order to improve the hemocompatibility of polycarbonateurethane (PCU), the biomimetic phosphorylcholine (PC) group was introduced onto material surface. Brush structure having PC groups was formed by ultraviolet (UV) initiated polymerization of 2-methacryloyloxyethyl phosphorylcholine (MPC) to improve the hydrophilicity and hemocompatibility of PCU surfaces. Fourier transform infrared (FTIR), X-ray photoelectron spectroscopy (XPS), scanning electrical microscopy (SEM) and water contact angle were used to characterize the chemical and physical properties of the modified PCU surfaces. Compared with original PCU, the PC-grafted PCU surfaces showed significantly high hydrophilicity as indicating by low water contact angle. The hemocompatibility of the PC-grafted PCU surfaces was evaluated by platelet adhesion test. The PCU surfaces modified with phosphorylcholine zwitterionic brushes showed effective resistance to platelet adhesion and high hemocompatibility. These PC-grafted PCU materials will have potential application as blood-contacting materials or devices due to their good mechanical and hemocompatible properties.
Abstract: Dynamic control of cell-substrate interactions is useful for exploring signaling processes involved in cell adhesion and migration as well as patterning heterotypic cells to mimic living tissues. We have developed photoactivatable substrates whose surface was modified with photoreleasable cell-repellent blocking agents. The surfaces are initially non-cell adhesive because of the presence of the blocking agents, but become cell adhesive upon near-UV irradiation of the substrates via the photo-induced desorption of the blocking agents. Here, I overview the developmental process of our photoactivatable substrates and demonstrate their potential uses for bioanalysis.
Abstract: The influence of citric acid on phase evolution of calcium phosphate is studied by the electrical conductivity of reaction solutions. The conductance curves are divided into three distinct regions and assigned to the formation of amorphous calcium phosphate (ACP), hydroxyapatite (HA) and the solubility of HA, respectively. When more citric acid is added, the width of region I decreases because more Ca2+ ions would prefer to foster the nucleation of HA from ACP. Decreasing rate of conductivity in region II becomes smaller with more addition of citric acid because the supersaturation of HA decreases in solutions. And thus, HA powders with larger grain size are synthesized with more citric acid addition.
Abstract: Aqueous CdTe and organic CdSe/ZnS quantum dots (QDs) were encapsulated into SiO2 beads using various controlled sol-gel processes. Ligand exchange is a key to adjust the QD number in each bead and get a high photoluminescence (PL). Namely, partial ligand exchange from thioglycolic acid to 3-mercaptopropyotrimethoxysilane (MPS) on the CdTe QDs enables retention of the initial PL efficiency of the QDs in water, while the simultaneous addition of a poor solvent (ethanol) resulted in regulated assembly of the QDs through condensation of hydrolyzed MPS. SiO2 beads thus prepared had, for example, a diameter of 17 nm and contained 3 QDs each. The PL efficiency of these beads was 30%, while the initial PL efficiency was 38% in a colloidal solution. In addition, a method including surface silanization, phase transfer and self-assembly, and SiO2 shell growth has been developed to incorporate multiple hydrophobic CdSe/ZnS QDs into SiO2 beads where they are well suited for bio-application due to their high brightness, less-cytotoxic, and non-blinking nature. To investigate the potential use for labeling in bio-applications, SiO2 beads with multiple QDs were conjugated with IgG using streptavidin-maleimide as linkers. This preparation method is an important step towards fabricating intensely emitting biocompatible SiO2 beads impregnated with semiconductor QDs.
Abstract: In this work, glucose concentration in gastric cancer cell was determinaed based on a coupled enzyme catalyzed reaction. glucose oxidase (GOD) reacted with glucose to form gluconic acid and H2O2. In the presence of horseradish peroxidase (HRP), the H2O2 then reacted with 10-acetyl-3,7- dihydroxyphenoxazine (ADHP) in a 1:1 stoichiometry to generated the fluorescent products, resorufin. So that, the glucose concentration assay could be performed by fluorometric analysis resorufin. Glucose solution or Gastric cancer cells lysate were catalyzed and detected by epi-fluorescence microscopy in a quartz capillary fluorometer cell. The fluorescence intensity were analysis by the MetaMorph Software. The linear relationship of the glucose concentrations covered a range of 1.00×10-8-1.00×10-5 mol/L with a correlation coefficient of 0.9994. LOD was 5.30×10-9 mol/L(cL = ksB/b). The glucose concentration in cancer cells lysate was 8.03×10-6 mol/L (n =4).
Abstract: In this work, titanium oxide nanorod arrays were fabricated by using the hydrothermal method on fluorine-doped tin oxide (FTO) coated glass. The diameter of the nanorods could be controlled from 150 nm to 30 nm by changing the growth parameters. The surface morphology and the structure of the samples were characterized by SEM and XRD. The wetting properties were identified by contact angle measurement. Platelet attachment was investigated to evaluate the blood compatibility of the samples with different nanoscale topographies. Results show that the nanotopographical surfaces perform outstanding blood compatibility, and the adhering platelet decreased with the increasing diameter of the nanorods.
Abstract: A review is provided dealing with the definitions and classifications of biosensors, as well as their basic working principles. Then, their applications to the environmental monitoring, which include the monitor of biochemical oxygen demand (BOD), bacterial count and various organic and inorganic pollutants, e.g. nitrogen compounds, heavy metal ions, organophosphorus pesticides, phenolic compounds, toxic compounds, carcinogens, teratogens, benzenes, sulfur dioxide, aldehydes and ethanols are presented. In the end, some suggestions were given with respect to the current problems of biosensors and the future applications of biosensors were also discussed.
Abstract: Phase change PVA / PEG composite nanofibers were prepared by electrospinning, micro-morphology of PVA / PEG fibers with different weight content were analyzed, the phase change characteristics were also analyzed. The result showed that well distributed composite nanofibers which composed by PVA/PEG blend solution can be obtained by electrospinning.PVA fibreforming were influenced because of the existence of PEG, including bond, irregular block, small rough, uneven diameter distribution in fibers. PVA/PEG blend solution of 4:6 weight content was well fibreforming compared with other different weight content.The continuity of spinneret flow in electrospinning would directly affected by polymer solution consentrition and viscosity. Further research about which and the influence in fibers diameter and morphology will be explored. Composite nanofibers possessed reversible phase transition characteristics,Tm Essentially unchanged ,Tc were related to the weight percentage of PEG/PVA, at the same time, the enthalpy will increase along with the gradually increase in weight percentage of PEG.
Abstract: Thermo-sensitive hydrogel have broad application prospects in biochemistry, medicine and other fields. In this paper, PEG as low melting point polymer was grafted at PVA which was as polymer framework of high melting point by copolymerization, a serials of new reversible phase-change materials were obtained and thermo-sensitive hydrogel were prepared because of their swelling properties. The hydrogel swelling behavior was analyzed, thermo-sensitive properties analysis was made by using DSC method, xerogel phase transition behavior was also studied and through which the relationship between PEG phase transition temperature and thermo-sensitive behaviors of the hydrogel was studied. The results showed that the thermo-sensitive hydrogel phase transition temperature was in the range of 36.3~43°C,and the phase transition temperature and the temperature sensitivity existed a certain relationship.