Biomedical subjects

Bo Zou

Publications and source records attributed to Bo Zou.

7 recordsLinked to original sources

PubMed2006

Dynamic light-scattering analysis of the electrostatic interaction of hexahistidine-tagged cytochrome P450 enzyme with semiconductor quantum dots.

Currently, there is great interest in the development of methods suitable for determining the stoichiometry of biomolecules attached to nanoparticles. We describe the use of the dynamic light-scattering technique (DLS) to determine the stoichiometry of the protein cytochrome P450(BSbeta) attached to CdS and CdSe quantum dots (QDs). The enzyme-conjugated QDs have different diffusion characteristics compared to the QD and enzyme precursors, expressed in their size, scattering intensity as well as zeta-potential values. The significant enhancement of the scattering intensity of QDs observed upon conjugation with the P450(BSbeta) due to the refractive-index increment and the systematic variation in zeta potential resulting from charge neutralization of the anionic QDs by the cationic histidine-tagged P450(BSbeta) have been used for stoichiometry determination.

Anions↗

PubMed2006

Synthesis and surface properties of new ureas and amides at different interfaces.

The influence of the urea and amide group in the alkyl chain of methyl nonadecanoate on the surface properties is investigated and compared. For that purpose, the ureas CH3O2C-(CH2)m-NHCONH-(CH2)n-CH3 (n + m = 14) [1 (m = 2), 3 (m = 3), and 5 (m = 4)] and the amides CH3O2C-(CH2)m-NHCO-(CH2)n-CH3 (n + m = 15) [2(m = 2), 4 (m = 3), and 6 (m = 4)] were synthesized. The pi/A isotherms of the ureas show up to the attainable temperature of 313 K no LE phase, which indicates a very stable LC phase. The amides exhibit a two phase plateau region, with the exception of 2. The different behavior is connected with the hydrogen bond energies, which are stronger with the ureas in the LC than in the LE phase, whereas those of the amides have a similar strength in both phases. The effect of hydrogen bonds in self-assembled molecules of N,N'-dialkylurea CH3-(CH2)m-NHCONH-(CH2)n-CH3 (m + n = 14) [7 (n = 2)] was visualized by STM at the octylbenzene/graphite interface. Compound 7 forms a lamella structure with a periodicity of one molecule length. The tilt angle of 86 degrees +/- 2 degrees to the edge of the lamella points to a nearly orthogonal arrangement of the molecules. It indicates two equivalent bonds between the aza-hydrogens and the carbonyl oxygen. A similar arrangement is proposed for the LC phase of the ureas at the air/water interface.

Amides↗

PubMed2006

[Application of functionally generated path technique in computer-aided-design modeling of occlusal surface of full crown].

OBJECTIVE: To apply the functionally generated path (FGP) technique for modeling the occlusal surface of a computer-aided-design (CAD) posterior full crown to obtain anatomic morphology. METHODS: A patient with defected left mandibular first molar was employed. After tooth preparation and impression making, the gypsum working cast and die were scanned with a digitized mechanical scanner and the surface data was acquired. The interocclusal records at intercuspal position (ICP) and FGP were made in the patient's mouth. These records were placed on the working cast and their surfaces were scanned. In the process of the computer-aided designing full crown, the cusps and fossae of the occlusal surfaces were accurately modified according to the digitized information of ICP and FGP interocclusal records. RESULTS: A full crown was designed and the occlusal morphology of the restoration was adapted to dynamic occlusion as well as static occlusion. CONCLUSIONS: The FGP technique was practical for the CAD of full crown and could avoid potential occlusal interferences with opposing teeth during function.

Adult↗

PubMed2005

Simple and complex lattices of N-alkyl fatty acid amides on a highly oriented pyrolytic graphite surface.

STM investigations of three N-alkyl fatty acid amide molecules have been carried out to get information of their molecular arrangement on a highly oriented pyrolytic graphite surface. With variable positions of amide along the alkyl chain, complex lattices with different lattice constants were observed. Besides the lattices with a repeat unit matching one or two molecular lengths, a lattice with a repeat unit corresponding to three molecular lengths was found. In addition, the portion of different lattices depends on the length of the shorter alkyl chain. DFT-D calculations point to interactions of antiparallel oriented dipoles due to the amide group, which are distance dependent and thus larger for shorter N-alkyl chains.

Journal Article↗

PubMed2003

Stabilizing bolaform amphiphile interfacial assemblies by introducing mesogenic groups.

We describe the synthesis and characterization of the mesogen-bearing bolaform amphiphile 4,4'-dihydroxybiphenylbis(11-pyridinium-N-yl-undecanoic ester) dibromide (BP-10) and its solid/liquid interfacial self-assembly. Cylindrical micelles are directly observed by atomic force microscopy (AFM) at the interface between mica and the aqueous solution above the critical micelle concentration (cmc). In situ and ex situ AFM studies indicate that the cylindrical micelles are stable both at the mica/solution interface and in the dry state. The enhanced stability of the micellar structures enables a detailed investigation of their self-assembly behavior and supramolecular structures at the interface. The adsorption model proposed here is supported by the variation of the interfacial self-assemblies on changing the solution concentration and substrate temperature.

Journal Article↗

PubMed2002

Confined supramolecular nanostructures of mesogen-bearing amphiphiles.

Stable surface nanostructures with different morphology have been successfully constructed by modifying the chemical structure of synthetic amphiphiles; by introducing mesogenic groups into bolaform amphiphiles, stable spaghetti-like or stripe-like nanostructures can be obtained; it is believed that such a kind of surface structure could be used for templating synthesis and assembly.

Journal Article↗

PubMed2002

The research and development of CAD-CAM system in restorative dentistry.

OBJECTIVE: To develop a dental CAD/CAM system with the autonomic intellectual property. METHOD: 28 standard teeth crowns were scanned using a newly 3-D laser scanner. As a development platform the Matlab 5.3 were used to process the acquired data, also be used to define the characterized areas on the surfaces of the crowns and to change the crowns form. The software of Surfacer 10.5 to develop a new CAD software for fixed prosthetics, and the 3.5 axis numerical controlled machine to manufacture the prosthetics were used. RESULT: It is the first time, the 3D graphic data bank of Chinese teeth crowns with a standard form was established. A software of the occlusal adjustment and the form modification were developed. It is also the first time, the authors realized the whole process to use the CAD-CAM for the manufacture of a crown. CONCLUSION: The successful result shows, that we have already mastered well the base theory, the mathematics method, the technology of a CAD-CAM system. It provides the basics for the future development.

Computer-Aided Design↗