The chemistry and use of cellulose derivatives for the study of biological systems

Cellulose chemistry and applications as carrier for proteins, polymers, and organic molecule

Chromatographic Separation Apparatus

An apparatus for the monitoring of a column chromatography separation process includes a segmented column with a seal positioned at the joint defined by the segments of the column. A connector is provided for connecting the segments of the column together. The apparatus further includes a sensor for monitoring an analyte in an eluant within a separation zone of the column. The sensor includes a mesh grid made of optical fibers or metal wires which is placed so as to extend through the separation zone of the column. The metal wires or optical fibers extend through the seal of the joint in the segmented column and connect to signal processing and data analysis equipment for purposes of monitoring the movements and concentration of an analyte in an eluant at various locations within the column. Certain segments of the optical fibers or metal wires which make up the mesh grid are coated so as to be desensitized and other segments are uncoated for sensing the analyte. This provides an effective apparatus to monitor in detail the cross-section of a column chromatography process in-situ

Electrochemically synthesized polymers in molecular imprinting for chemical sensing

This critical review describes a class of polymers prepared by electrochemical polymerization that employs the concept of molecular imprinting for chemical sensing. The principal focus is on both conducting and nonconducting polymers prepared by electropolymerization of electroactive functional monomers, such as pristine and derivatized pyrrole, aminophenylboronic acid, thiophene, porphyrin, aniline, phenylenediamine, phenol, and thiophenol. A critical evaluation of the literature on electrosynthesized molecularly imprinted polymers (MIPs) applied as recognition elements of chemical sensors is presented. The aim of this review is to highlight recent achievements in analytical applications of these MIPs, including present strategies of determination of different analytes as well as identification and solutions for problems encountered

Comparing recovering efficiency of immunomagnetic separation and centrifugation of mycobacteria in metalworking fluids

The accurate detection and enumeration of Mycobacterium immunogenum in metalworking fluids (MWFs) is imperative from an occupational health and industrial fluids management perspective. We report here a comparison of immunomagnetic separation (IMS) coupled to flow-cytometric enumeration, with traditional centrifugation techniques for mycobacteria in a semisynthetic MWF. This immunolabeling involves the coating of laboratory-synthesized nanometer-scale magnetic particles with protein A, to conjugate a primary antibody (Ab), specific to Mycobacterium spp. By using magnetic separation and flow-cytometric quantification, this approach enabled much higher recovery efficiency and fluorescent light intensities in comparison to the widely applied centrifugation technique. This IMS technique increased the cell recovery efficiency by one order of magnitude, and improved the fluorescence intensity of the secondary Ab conjugate by 2-fold, as compared with traditional techniques. By employing nanometer-scale magnetic particles, IMS was found to be compatible with flow cytometry (FCM), thereby increasing cell detection and enumeration speed by up to two orders of magnitude over microscopic techniques. Moreover, the use of primary Ab conjugated magnetic nanoparticles showed better correlation between epifluorescent microscopy counts and FCM analysis than that achieved using traditional centrifugation techniques. The results strongly support the applicability of the flow-cytometric IMS for microbial detection in complex matrices.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/47949/1/10295_2005_Article_238.pd

An evanescent wave sensor for the detection of organophosphorus compounds based on the inhibition of cholinesterase

261-265<span style="font-size:11.0pt;line-height: 115%;font-family:Calibri;mso-fareast-font-family:" times="" new="" roman";mso-bidi-font-family:="" "times="" roman";mso-ansi-language:en-us;mso-fareast-language:en-us;="" mso-bidi-language:ar-sa"="" lang="EN-US">A flow injection analysis (FIA) system coupled with an evanescent wave (EW) sensor employing total internal reflection of fluorescence radiation (TIRF) for the detection of the organophosphorus compounds is reported. The detection is based on the measurement of acetylcholinesterase (AChE) inhibition in the presence of organophosphorus compounds. AChE was immobilized on controlled pore glass (CPG) particles and packed into a teflon column which was then coupled to the evanescent wave sensor. A constant concentration of acetylthiocholine in Tris-HCI buffer (10 mM, pH 7.5) was pumped through the enzyme column. The thiocholine formed as a result of the AChE catalyzed reaction in the column was monitored by the injection of 7-diethylamino-3-( 4' -maleimidylphenyl)-4-methylcoumarin (CPM) which forms a highly fluorescent compound with thiocholine. The CPM-thiocholine complex was excited with the evanescent wave and the resulting fluorescence was detected by a Himamastsu S-2387/66R detector. Varying concentrations of paraoxon were injected through the enzyme column and the extent of enzyme inhibition was recorded by the injection of the optimum concentration of the CPM. The difference of the two responses in the presence and absence of the paraoxon determines the extent of inhibition. The acetycholinesterase activity was then reactivated by the injection of pyridine 2-aldoxime methiodide (2-PAM) which results in the recovery of the initial response.</span