Biomedical subjects

Cameron D Skinner

Publications and source records attributed to Cameron D Skinner.

6 recordsLinked to original sources

PubMed2006

Pore size characterization of monolith for electrochromatography via atomic force microscopy studies in air and liquid phase.

This paper investigates the use of scanning electron microscopy (SEM) and atomic force microscopy (AFM) for the characterization of monoliths used in capillary electrochromatography (CEC) while focusing on the nature of the information available from both techniques. SEM imaging revealed a compact structure of non-porous micrometer sized particles homogeneously agglomerated. With a simple AFM methodology, we found by direct observation that the same material exhibits mesopores in the nanometer range while SEM showed non-porous surfaces. These results obtained by AFM clearly showed that micrometer sized particles shrank and micrometer sized pores increased in the monolith when wetted. Thus, AFM was capable of demonstrating the morphological differences between wet and dried monolithic materials that are not possible by other imaging methods at micrometer resolution.

Chromatography, Micellar Electrokinetic Capillary↗

PubMed2006

Characterization of UV-transparent capillaries for CEC and CE.

This short communication describes features of UV-transparent capillaries employed for CEC and CE. A waveguide effect was observed when using UV-transparent capillaries. Through imaging with SEM, the UV-transparent coating was found to be highly porous unlike polyimide coating, which did not exhibit any porosity at all. Prolonged exposure to several commonly employed solvents with elevated pH caused abrasion of the coating at the capillary tip but no swelling of the UV-transparent coating was observed. Lastly, four different cutting techniques were compared to obtain smooth capillary tips.

Chromatography, Liquid↗

PubMed2005

Insulin-like growth factor II and binding proteins 1 and 3 from second trimester human amniotic fluid are associated with infant birth weight.

The developing fetus begins to swallow amniotic fluid (AF) early in gestation, a process that results in ingestion of numerous growth factors. Our objectives were 2-fold: 1) to assess the concentration and distribution of insulin-like growth factor II (IGF II) and its binding proteins (BP) 1 and 3 in 2nd trimester amniotic fluid using ELISA, and 2) to establish whether concentrations of AF IGF II and its binding proteins IGF BP1 and 3, measured early in pregnancy, were associated with and predictive of infant birth weight. Birth weights were categorized using recently developed birth-weight-for-gestational-age percentiles for fetal growth in which infants < 10% were classified as SGA (small-for-gestational-age) and those > 90% as LGA (large-for-gestational-age). AF samples were collected after routine genetic testing (15.1 +/- 0.04 wk, range 12-20 wk) from 543 mother-infant pairs in Montreal, QC, Canada. Maternal and fetal characteristics were obtained from questionnaires and medical chart review. Multivariate regression analysis that controlled for maternal height, prepregnancy weight, smoking behavior, infant gender, gestational age, parity, as well as amniocentesis week showed that higher AF IGF BP1 was associated with lower birth weight (partial r2 = 0.0062). Regression analyses revealed that AF IGF BP3 was positively associated with birth weight within LGA and macrosomia subpopulations (partial r2 = 0.0283 and 0.0404, respectively). These results show that 2nd trimester AF IGF BP1, BP3, and IGF II may emerge as early indicators of fetal growth.

Amniotic Fluid↗

PubMed2004

Capillary electrochromatography of peptides and proteins.

This review surveys the accomplishments in the separation of peptides and proteins by capillary electrochromatography (CEC) over the last decade. A significant number of research articles have been published on this topic since the last review. Peptide and proteins separations have been carried out in all three formats of CEC, i.e., packed bed, continuous bed and open-tubular (OT) format. In addition to electrophoresis, different chromatographic modes have been successfully exploited with the most prevalent being reversed-phase mode followed by ion-exchange. Although many researchers continue to use model proteins and peptides primarily to evaluate the performance of novel stationary phases some researchers have also applied CEC to the analysis of real-life samples. The potential of CEC to yield complementary information and sometimes a superior separation with respect to established techniques, i.e., microbore HPLC and capillary electrophoresis has been demonstrated. Instrumental modifications in order to facilitate coupling of CEC to mass spectrometry have further upgraded the value of CEC for proteomic analysis. Capillaries are still the separation vehicle of choice for most researchers yet the microfluidic platform is gaining momentum, propelled particularly by its potential for multitasking, e.g., performing different chromatographic modes in series.

Chromatography, Micellar Electrokinetic Capillary↗

PubMed2003

Protein separation by monolithic capillary electrochromatography.

This work presents the separation of model proteins by capillary electrochromatography involving a monolithic stationary phase with C4 functionality. The monolith was fabricated in UV-transparent capillaries by employing a slight modification of a recently published photopolymerization procedure. With the number of theoretical plates per column ranging between 11000 and 33000, the separation efficiency proved to be lower than capillary zone electrophoresis where plate numbers ranged between 18000 and 66000. However, higher resolution was obtained due to the additional chromatographic separation mechanism. Inter- and intra-column reproducibility were evaluated, the latter could be significantly improved when using a rinsing procedure that contained 0.05% sodium dodecylsulfate in the mobile phase. Plate heights became nearly independent of mobile phase velocities higher than 0.5 mm/s indicating that high velocities can be applied without sacrificing efficiency. Furthermore, peak heights showed a dependence on injection times. For proteins, an increase in capacity factors was found when increasing the percentage of organic solvent in the mobile phase.

Chromatography, Micellar Electrokinetic Capillary↗

PubMed2003

A two bead immunoassay in a micro fluidic device using a flat laser intensity profile for illumination.

Recently it was demonstrated that a collimated Gaussian beam can be converted to a flattop beam using a Keplerian beam reshaper consisting of two aspheric lenses. Here, using the same optical system, we demonstrate that this flattop profile can be maintained when used in a confocal detection system that focuses the laser beam into a diameter of only 33 microm. The intensity profile of the reshaped beam was determined by imaging the excitation of a constant stream of fluorescein inside a microfluidic device. The resulting shape had a 6.38% RSD intensity across the flat profile when imaged with a CCD camera. This flat illumination profile was then used in a two bead multiplex immunoassay where the colour combination and/or the intensities can be used to determine the presence of an antigen. Detection limits of TNF-alpha and IL-6 were comparable with standard ELISA immunoassays.

Journal Article↗