Chuanfeng Zhu

Phage M13Ko7 Detection With Biosensor Based On Imaging Ellipsometry And Afm Microscopic Confirmation

Abstract A rapid detection and identification of pathogens is important for minimizing transfer and spread of disease. A label-free and multiplex biosensor based on imaging ellipsometry (BIE) had been developed for the detection of phage M13KO7. The surface of silicon wafer is modified with aldehyde, and proteins can be patterned homogeneously and simultaneously on the surface of silicon wafer in an array format by a microfluidic system. Avidin is immobilized on the surface for biotin-anti-M13 immobilization by means of interaction between avidin and biotin, which will serve as ligand against phage M13KO7. Phages M13KO7 are specifically captured by the ligand when phage M13KO7 solution passes over the surface, resulting in a significant increase of mass surface concentration of the anti-M13 binding phage M13KO7 layer, which could be detected by imaging ellipsometry with a sensitivity of 109 pfu/ml. Moreover, atomic force microscopy is also used to confirm the fact that phage M13KO7 has been directly captured by ligands on the surface. It indicates that BIE is competent for direct detection of phage M13KO7 and has potential in the field of virus detection.

A triphenylene-containing side chain liquid crystalline ladder-like polysiloxane and its highly ordered superstructure

A liquid crystalline discotic triphenylene-containing side chain ladder-like polysiloxane (LPS) derivative was prepared by hydrosilylation. The superstructure was investigated by X-ray diffraction (XRD), atomic force microscopy (AFM) and isotherm surface pressure (π)-area (A) diagrams based on LB-film experiments. The XRD results suggest that the discotic triphenylene units in the side chains stack to form a columnar structure and the columns further align with each other to form a board-like superstructure because of the semi-rigidity of the ladder-like backbone. This suggestion has been confirmed by parallel nanowire-like stripes observed in the AFM image. Mixing small amounts of the corresponding low molar mass molecules with the polymer leads to a more ordered and denser columnar stacking, as shown by sharpened XRD patterns and a π-A curve with a steeper slope, higher collapse pressure and lower collapse area than those obtained either for the low molar mass molecules or the polymer individually.

Scanning tunneling microscopy of silver containing salt of bis(ethylenedithio)tetrathiafulvalene

The surface of silver containing salt of bis(ethylenedithio)tetrathiafulvalene (BEDT‐TTF) was studied with the computer‐controlled scanning tunneling microscope developed in our laboratory. The crystal surface of the charge‐transfer complex is well ordered and a regular array of corrugations is clearly visible. The prominent feature of the experimental scanning tunneling microscopy images is in agreement with the bulk crystal structure obtained by x‐ray diffraction method.

A combined method based on rubbing and UV-irradiation for preparing stable alignment-layers with high pretilt angles

Abstract A novel two-step method combining rubbing and UV-irradiation based on ladderlike polysilsesquioxanes (LPS) containing cinnamate and azobenzene side chains was developed to obtain alignment layers which features a high surface pretilt angle and good stability. At the first step, a low pretilt angle of 1–3° was generated by rubbing and at the second step, an increased pretilt angle of about 11° was obtained through further UV-irradiation. The polarized optical micrograph and the conoscopic picture prove that good LC alignment state with a stable high pretilt angle can be obtained by in situ photo-crosslinking of the cinnamate side-chains through proper UV-irradiation. The high pretilt angle arises from the photo-induced tautomerization of azobenzene side chains and that is confirmed by AFM study. In particular, the annealing test near the clearing point indicates the high stability of the high pretilt state, which heralds their potential application in LCD such as producing a patterned alignment la...

Scanning tunneling microscopy of the phosphatidylcholine bilayers

The bare surface of the egg‐PC bilayers after being dried at room temperature was observed by the STM and images with angstrom resolution were obtained. Results indicate that the lipid heads form islands of an average of 210 A in diameter and 40 A in separation on the bilayers and that each island contains about 170 lipid heads of 7.5 A in diameter. The size of the lipid heads is correspondent with that calculated from the standard bond distances and the bond angles. The ordered distribution of the lipid heads in some areas may correspond to the ordered arrangement of the lipid heads on the egg‐PC bilayers before being dried. The STM results also show that there exists the ripple phase in the egg‐PC bilayers below its phase transition temperature.

Scanning tunneling microscopic imaging of doped polyaniline

Abstract Scanning tunneling microscopic images of doped polyaniline (PANI) with HCl are presented. Parallel chains with average separation of 0.4 nm are clearly visible, and the measured distance between the nearest two maxima in the polymer chain is about 1.04 nm. Molecular-mechanic calculations were used to optimize the conformation of a model polyaniline chain, and have yielded numerical values which agree well with measurements taken from the STM images.