Proposed methods for detecting circulatory system disease include targeting ultrasound contrast agents to inflammatory markers
on vascular endothelial cells. For antibody-based therapies, soluble forms of the targeted adhesion proteins of the immunoglobulin
superfamily (IgSF) reduce adhesion yet were left unaccounted in prior reports. Microspheres labeled simply with a maximum
level of antibodies can reduce the diagnostic sensitivity by adhering to proteins expressed normally at a low level, while
sparsely coated particles may be rendered ineffective by circulating soluble forms of the targeted proteins. A new microdevice
technique is applied to simultaneously measure the adhesion profile to a series of IgSF-protein-coated surfaces. In this investigation,
we quantify the in vitro binding characteristics of 5-μm microspheres to oriented intercellular adhesion molecule-1 (ICAM-1)
and vascular cell adhesion molecule-1 (VCAM-1) protein-coated surfaces in the presence of human serum at physiological concentrations.
Defined regions of a slide were coated with recombinant chimeric Fc-human ICAM-1 and VCAM-1 in variable ratios but constant
total concentration. Monoclonal human anti-ICAM-1 or anti-VCAM-1 antibodies in competition with non-binding mouse anti-rabbit
antibodies coat the microsphere surface at a constant surface density with variable yet controlled surface activities. Using
multiple slide surface IgSF protein and microsphere antibody concentrations, an adhesion profile was developed for the microspheres
with and without IgSF proteins from human serum, which demonstrated that exposure to serum reduced microsphere binding, on
average, more than 50% compared to the no-serum condition.. The serum effects were limited to antibodies on the microsphere,
since binding inhibition was reversed after rinsing serum from the system and fresh antibody-coated microspheres were introduced.
This analysis quantifies the binding effects of soluble IgSF proteins from human serum on antibody-based targeted ultrasound
detection and drug delivery methods. 相似文献
This article reviews progress in the application of electrophoretic techniques for the separation of nanoparticles. Numerous types of nanoparticles have recently been synthesised and integrated into different products and procedures. Consequently, analytical methods for the efficient characterisation of nanoparticles are now required. Several studies have revealed that gel electrophoresis can readily be used for separating nanoparticles according to their size or shape. However, many other studies focused on separation of nanoparticles by CE. In some cases nanoparticles could be separated by CZE, simply using pure buffer as the BGE. In other studies, buffer additives (most often SDS) were used, enabling fast separations of metallic nanoparticles by size. Other CE methods also allowed for separation of nanoparticle conjugates with biomolecules. Dielectrophoresis is yet another electrophoretic technique useful in separation and characterisation of nanoparticles; particularly nanotubes. Detection methods often used after electrophoretic separation include UV/Vis absorption and fluorescence spectroscopy. Examples of recent and relevant older reports are presented here. The authors conclude that electrophoretic methods for nanoanalysis can provide inexpensive and efficient tools for quality assurance and safety control; and as a consequence, they can augment transfer of nanotechnologies from research to industry. 相似文献
We report the structure–activity relationship in the antimicrobial activity of linear and branched poly(ethylene imine)s (L‐ and B‐PEIs) with a range of molecular weights (MWs) (500–12 000). Both L‐ and B‐PEIs displayed enhanced activity against Staphylococcus aureus over Escherichia coli. Both B‐ and L‐PEIs did not cause any significant permeabilization of E. coli cytoplasmic membrane. L‐PEIs induced depolarization of S. aureus membrane although B‐PEIs did not. The low MW B‐PEIs caused little or no hemolysis while L‐PEIs are hemolytic. The low MW B‐PEIs are less cytotoxic to human HEp‐2 cells than other PEIs. However, they induced significant cell viability reduction after 24 h incubation. The results presented here highlight the interplay between polymer size and structure on activity.
We report on infrared laser spectroscopic measurements of the isotopic composition of methane (12CH4, 13CH4) in natural air samples with a cavity ring-down technique. A CO overtone sideband laser is utilized to excite a high-finesse
cavity which provides an effective optical absorption path length of 3.6 km. We achieved a detection limit of 105 ppt methane
in ambient air using an integration time of 20 s. This corresponds to a minimum detectable absorption of 1.9×10-9 /cm. Rapid determination of the 13C/12Cisotopic ratio of methane in ambient air without sample preconcentration or gas processing is realized. The present system
requires only few minutes for an isotopic ratio measurement with a precision of 11%o .
Received: 14 July 2000 / Revised version: 25 October 2000 / Published online: 6 December 2000 相似文献
Recent high-voltage electron microscopy has provided evidence that substantial submicroscopic changes may occur in specimens examined in the HVEM under conditions where no visible radiation damage occurs. These are the introduction of vacancies by plastic deformation, rapid accumulation of invisible vacancy clusters by electron irradiation, and radiation-induced contamination and refining of materials. These processes are analysed in terms of defect interactions and the consequences for in-situ experiments are discussed. 相似文献
More than 800 Δk = ±2 and 60 Δk = ±3 forbidden transitions to the ν4 and 2ν2 vibrational levels, respectively, have been assigned in the Fourier transform spectra of 15NH3, recorded with a pathlength of 96 m. Combination differences derived from these transitions provide information on the spacing between the ground state energy levels with different rotational quantum numbers K in the interval from 0 to 16. These data along with wavenumbers of all the available allowed transitions pertaining to the ground and ν2 states have been subjected to a simultaneous least-squares analysis using two different parametrization models to obtain precise values of the inversion-rotation energy levels. 相似文献