Tissue phantoms constructed with hydrophobic nanoporous silica particles.

We describe a protocol to create tissue phantoms with hydrophobic nanoporous particles. The nanopores of the particles are loaded with biological molecules at the desired compositions. Tissue phantoms are prepared by immersing dried particles into aqueous biological matrixes.

Analysis of cationic liposomes by reversed-phase HPLC with evaporative light-scattering detection.

Cationic lipid-mediated drug delivery of small pharmaceutical molecules and biological molecules, such as proteins and DNA, has gained increasing popularity for many in vitro and in vivo applications. For this purpose, 1,2-dioleoyl-3-trimethylammonium propane (DOTAP) is one of the most widely used and efficient cationic lipids. In this work, a simple and rapid reversed-phase HPLC method was developed for the simultaneous determination of cationic lipid DOTAP and neutral co-lipids cholesterol and phosphatidylcholine (DPPC or DSPC) as well as their degradation products in liposome-based drug formulations.

Calibration of probe volume in fluorescence correlation spectroscopy.

In fluorescence correlation spectroscopy (FCS), an accurate evaluation of the probe volume is the basis of correct interpretation of experimental data and solution of an appropriate diffusion model. Poor fitting convergence has been a problem in the determination of the dimensional parameters, the beam radius, omega, and the distance along the optical axis of the probe volume, l. In this work, the instability of fitting during the calibration process is investigated by examining the chi(2) surfaces.

Microscopic origins of band broadening in chromatography. Polarity distribution in C(18) stationary phase probed by confocal ratiometric imaging of Nile red.

Band broadening is a major factor that influences the efficiency and resolution of chromatographic separations. Studies of microscopic origins of band broadening, such as the micropolarity distribution of chromatographic stationary phase, can provide a better understanding of many chromatographic phenomena and retention behavior. In this work, we probe the chemical environments of C18 chromatographic stationary phase with quantitative confocal fluorescence microscopy under real reversed-phase liquid chromatography conditions.

Probing strong adsorption of solute onto C18-silica gel by fluorescence correlation imaging and single-molecule spectroscopy under RPLC conditions.

Understanding molecular adsorption at a chromatographic interface is of great interest for addressing the tailing problem in chemical separations. Single-molecule spectroscopy and confocal fluorescence correlation imaging are used to study the adsorption sites of C(18) silica beads under RPLC chromatographic conditions. The experiments show that cationic molecule rhodamine 6G laterally diffuses through the chromatographic interface of a C(18) hydrocarbon monolayer and acetonitrile with occasional reversible strong adsorptions.

[Effect of oxygen on the fluorescence of sol-gel with ruthenium complexes].

Different Ru complexes were used in an organically modified sol-gel (ormosil) sensing film to character their quenching behaviors to oxygen. The sensing film with tris-(4,7-diphenyl-1, 10-phenanthroline) ruthenium(II) [Ru(dpp)(2+)3] as an indicator was selected because of its characteristics with high quenching efficiency, fast response time, high luminescence intensity and long-term stability. The quenching behavior of the sensing film greatly depended on the content of dimethyldimethoxysilane (DiMe-DMOS) in ormosil because DiMe-DMOS changed the polarity of sensing film.

Direct observation of frits and dynamic air bubble formation in capillary electrochromatography using confocal fluorescence microscopy.

Confocal fluorescence microscopy has been used to study the capillary electrochromatography (CEC) frits and dynamic air bubble formation under real chromatographic conditions. Confocal fluorescence microscopy provides a nondestructive way to view the three-dimensional structure of the frits with high spatial resolution. Frits prepared with four different procedures were studied: (1) sintering bare silica beads with sodium silicate; (2) sintering bare silica beads wetted with water; (3) sintering C18 beads wetted with water; and (4) sintering C18 beads wetted with water and then surfaced-recovered with C18.

Coordination-driven self-assembly directs a single-crystal-to-single-crystal transformation that exhibits photocontrolled fluorescence.

Coordination-driven self-assembly is employed to direct a single-crystal-to-single-crystal [2 + 2] photodimerization that exhibits tunable fluorescence.

[Oxygen sensing film based on organically modified sol-gel with ruthenium complexes and their fluorescent spectra studies].

A new kind of organically modified sol-gel (ormosil) as a matrix for oxygen-sensitive sensor, in which dimethyldimethoxysilane was selected as an organic modifier in the precursor is described. The fluorescent behaviors of different ruthenium complexes in solution and ormosil film were studied. The sensing film with different kind ruthenium complex as an indicator developed in this paper was characterized in terms of efficiently quenched by oxygen.