Supramolecular Science最新文献

The CdS nanoparticles synthesized in AOT (bis(2-ethylhexyl) sulfosuccinate, disodium salt) reverse micelle in addition of the electric neutral surface-capping agent of pyridine are characterized by XPS, TEM and the absorption spectra. The values of the first-order hyperpolarizability β for two kinds of nanoparticles, CdS/AOT^- and CdS/pyridine/AOT^-, have been experimentally measured in solution by the newly developed hyper-Rayleigh scattering technique. The values of β are larger than 10^-27 esu, which are among the largest values reported for solution species.

A cyanobiphenyl molecular film mixed with nonamphiphilic azobenzene and benzimidazole derivative dichroic dyes was transferred from an air–water interface onto a hydrophilic quartz plate. 4-cyano-4-octylbiphenyl is a liquid crystal material which played the role of a host in the mixed films. The mole fraction of dye to cyanobiphenyl molecules was varied from 0.5 to 0.02. One layer was successfully deposited onto a quartz plate with the transfer ratio slightly higher than one. The films were deposited at a surface pressure π between 1 and 15 mN/m. The structure of the film at the air–water interface was observed by using a Brewster angle microscope. The orientation of cyanobiphenyl as well as dye molecules were estimated by polarized absorption spectra. The angle of the cyanobiphenyl $\text{(β}{}_{\mathrm{<mtext>H</mtext>}}\text{)}$ molecules between the long molecular axis and normal to the quartz surface in pure and mixed monolayers was found to be between 64° and 54°. These values depend on the surface pressure during deposition. The smaller angles were observed for mixed layers and for high surface pressure. Analyzing polarized spectra of dyes incorporated in the monolayer made similar observations. The dyes show a sharper angle $\text{β}{}_{\mathrm{<mtext>G</mtext>}}\text{=(60°–38°)}$ than host molecules $\text{(β}{}_{\mathrm{<mtext>H</mtext>}}\text{=(64°–54°)}$. The dye absorption spectra at the high dye concentration and surface pressure differ from those for the films deposited at low concentration or low surface pressure.

MCM-41 mesoporous molecular sieve materials with nanometer-sized pores show the very strong photoluminescent (PL) effect and the Al-depleted defect sites are responsible for this strong PL effect of the investigated MCM-41 samples. The porous channel structures of molecular sieves are another factor influencing the investigated PL effect.

In our experiment colloidal gold was used to enhance the signal obtained from the surface-plasmonresonance biosensor. Fab′ fragments of human IgG molecules were immobilized on the gold surface and reacted with the sheep-anti-human IgG(SAH-IgG) molecules in solution. It was found that when the colloidal gold labeling technique was introduced the sensitivity of surface plasmon resonance instruments increased by a factor of about 300.

The α-Fe₂O₃ ultrafine particles were dispersed in the solutions of stearic acid/n-hexane/chloroform by the ultrasonic method, and fabricated by the Langmuir–Blodgett film technology. α-Fe₂O₃ ultrafine particles/stearic acid composite LB films were characteried by π–A curve, UV-visible absorption spectrum, IR spectrum, small angle X-ray diffraction, TEM and electron diffraction. The results showed the following: the αFe₂O₃ ultrafine particles were uniformly dispersed in organic solvents; the film-forming characterization of the α-Fe₂O₃ ultrafine particles/stearic acid monolayer was fine, the α-Fe₂O₃ ultrafine particles in the composite film had a small orientation; the α-Fe₂O₃ ultrafine particles/stearic acid composite film had a lamellar structure.

This paper presents a strategy for immobilizing biomolecules onto a solid surface. We used the free thiol group directing method to immobilize Fab’ fragments to the MPTMS derived quartz substrate and results of X-ray photoelectron spectroscopic studies on the binding of MTPMS and Fab’ fragments on the quartz surfaces are reported. We also prepared a new type of immuno-labeled protein which was the rare earth element labeled antigen (human IgG) to recognize Fab’ fragment. Four characteristic peaks has been determined on the surface specifically bound human IgG labeled Tb³⁺.

We synthesized a novel amphiphilic polymer consisting of octadecylacrylamide and N,N-dimethylacrylamide with a molar ratio of 99 : 1. The polymer-induced aggregation of liposomes in an adequate lipid/polymer ratio. However, calcein, a water-soluble fluorescent dye entrapped in the large unilamellar liposomes (LUVs) did not leak out significantly although hydrophobic residues of the polymer penetrated into the lipid bilayer. Liposome aggregates by the polymer could be easily collected by low-speed centrifugation for 10 min at 1400×g and no significant leakage of the entrapped calcein inside the liposomes was observed. Dynamic light scattering (DLS) measurements showed that liposomes were enlarged in apparent particle size being coated with the polymer or aggregated by cross-linking. The polymer-coated liposomes were more stable against the detergent than the liposomes without a polymer coating.

Tin phthalocyanine (SnPc)-doped polymer films were used to align ferroelectric liquid crystals (FLC). A stripe-shaped domain structure was obtained spontaneously in the initial alignment of the surface-stabilized cells. Atomic force microscopy (AFM) was introduced to investigate the aligning films. It was discovered that the modified aligning films show a polymer aggregate chain structure oriented along the rubbing direction that may play an important role in the FLC alignment. The stability, memory capability and response time of the cell were improved and enhanced through the doping process.

The interaction between poly-L-lysine (PLL) and photosynthetic reaction center (RC) from Rodopseudomonas viridis was studied with special interest for the Langmuir–Blodgett (LB) film preparation. PLL of low concentration (0.5mM) in the subphase of the LB trough as a counterion stabilized the protein at the air/water interface and enhanced the protein deposition efficiency onto the substrate. PLLs of various degree of polymerization (n=1, 5, 10, 15 and 20) were synthesized and the effect of each PLL was examined. Enhancement of the deposition of RC was observed using high n peptide (n=10, 15 and 20) but not using low n one (n=1 and 5). When PLL (n=1, 5, 10, 15 and 20) was added to the RC solution, the protein–protein association and the subsequent precipitation of RC occurred. Highly polymerized PLLs were effective on both RC deposition and RC precipitation suggesting that RCs spread at air/water interface were linked by PLL. The number of PLL molecules which were adsorbed on one RC molecule was 9.0 (±1.5) and 6.6 (±0.5) in the case of n=10 and 20 of PLL, respectively.

Cross-linked complex between photosynthetic reaction center and horse heart cytochrome c (cyt c) was prepared for the control of molecular orientation in Langmuir–Blodgett (LB) method. The surface of cyt c is highly hydrophilic whereas that of RC is hydrophobic. A polar distribution of hydrophobicity/hydrophilicity in the complex was realized by the cross-linkage of the different protein molecules. An index was introduced to evaluate the hydrophobicity of the surface of the proteins. The orientation of RCs in an LB film was evaluated by the displacement current. The complex showed a response 1.5 times larger than that of RC.