Human Serum

A sensitive optical method based on quantum dot (QD) technology is demonstrated for the detection of an important cancer marker, total prostate-specific antigen (TPSA) on a disposable carbon substrate surface. Immuno-recognition was carried out on a carbon substrate using a sandwich assay approach, where the primary antibody (Ab)-protein A complex covalently bound to the substrate surface, was allowed to capture TPSA. After the recognition event, the substrate was exposed to the biotinylated secondary Abs. After incubation with the QD streptavidin conjugates, QDs were captured on the substrate surface by the strong biotin-streptavidin affinity. Fluorescence imaging of the substrate surface illuminated the QDs, and provided a very sensitive tool for the detection of TPSA in undiluted human serum samples with a detection limit of 0.25ng/mL. The potential of this method for application as a simple and efficient diagnostic strategy for immunoassays is discussed.

Memory impairment is a process associated with alterations in neuronal plasticity, synapses formation, and stabilization. As the neural cell adhesion molecule (NCAM) plays a key role in synaptic bond stabilization, we analyzed the usefulness of soluble NCAM isoforms in the diagnosis of patients with dementia of the Alzheimer type (DAT).NCAM was measured in the sera of 70 control subjects and

In this paper, a novel graft copolymer, poly-(L-lysine)-graft-poly(ethylene glycol) (PLL-g-PEG) with part of the PEG chains carrying a terminal nitrilotriacetic acid group (NTA) was synthesized. Through electrostatic interactions, these polycationic graft co-polymers assemble spontaneously from aqueous solution onto negatively charged surfaces, forming polymeric monolayers that present NTA groups at controlled surface densities on a highly PEGylated background. The NTA-functionalized PLL-g-PEG surfaces proved to be highly resistant to nonspecific adsorption in contact with human serum while allowing the specific and reversible surface binding of GFPuv-6His and β-lactamase-6His in native conformation. Micropatterns consisting of NTA-functionalized PLL-g-PEG in a background of PLL-g-PEG were produced using the "molecular assembly patterning by lift-off" technique. Exposure to Ni<sup>2+</sup>and GFPuv-6His resulted in a protein pattern of excellent contrast a...

Background: The Dutch project" Calibration 2000" aims at harmonization of laboratory results via calibration by development of commutable, matrix-based, secondary reference materials. An alternative approach to the NCCLS EP14 protocol for studying commutability ...

Fluorescence spectroscopy and circular dichroism (CD) spectroscopy were used to investigate the interaction of coumarin-3-carboxylic acid with human serum albumin (HSA) and bovine serum albumin (BSA) under physiological conditions in a buffer solution of pH 7.4. Quenching constants were determined using the Lineweaver-Burk equation to provide a measure of the binding affinity of coumarin-3-carboxylic acid to HSA/BSA. Binding studies concerning

A periodate-resorcinol microassay for the quantitation of total sialic acid (TSA) has been developed. A 96-well microtiter plate format was used as a single reagent mixing well. The principle of this newly-developed assay is the periodate-resorcinol procedure. Conditions for the quantitation of sialic acid in serum, such as the concentration of periodate, resorcinol, incubation time and human serum volume, were optimized. It was found that the optimal concentration of periodic acid and resorcinol reagent were 1.3 mM and 0.6%, respectively. An incubation time of 60 minutes for the reaction of periodic acid and resorcinol with samples was found to give the highest absorbance. These new procedures were used for the quantitation of sialic acid in human serum. It was found that only 5 µL samples were needed to give a varied coefficient of the intra- and inter-assay of 0.79% and 4.68%, respectively. Furthermore, this method demonstrated the recovery percentage of 94.25% by the addition of...

A Glutathione (GSH) optical sensor with high sensitivity and exceptional selectivity was developed using one-step synthesized-upconversion nanoparticles (UCNPs, NaLuF4:Gd3+,Yb3+,Er3+) in conjunction with a Rhodamine B derivative (RBD). RBD was loaded on the surface of the UCNPs though non-covalent bonding to serve as an energy acceptor, while UCNPs served as energy donors. The sensor based on a coupling fluorescence resonance energy transfer (FRET) process at an excitation of 980 nm wavelength from UCNP to RBD with a ringopening process of RBD after the addition of GSH. The sensing probe exhibits a remarkable
limit of detection (LOD = 50 nM) for GSH through the enhancement of the fluorescence intensity of RBD at 592 nm, together with a concomitant reduction in the green band of the UCNPs. In addition, the sensing mechanism, characterization of UCNPs, and the selectivity of the fluorescence sensor toward GSH were discussed. The proposed sensor was evaluated on real human serum and urine samples and demonstrated as a highly selective and sensitive probe for the detection of GSH.