Determination of human serum albumin using aurothiomalate as electroactive label

Abstract

A new electroactive label has been used to monitor immunoassays in the determination of human serum albumin (HSA) using glassy-carbon electrodes as supports for the immunological reactions. The label was a gold(I) complex, sodium aurothiomalate, which was bound to rabbit IgG anti-human serum albumin (anti-HSA-Au). The HSA was adsorbed on the electrode surface and the immunological reaction with gold-labelled anti-HSA was then performed for one hour by non-competitive or competitive procedures. The gold(I) bound to the anti-HSA was electrodeposited in 0.1 mol L-1 HCl at -1.00 V for 5 min then oxidised in 0.1 mol L-1 H2SO4 solution at +1.40 V for 1 min. Silver electrodeposition at -0.14 V for 1 min followed by anodic stripping voltammetry were then performed in aqueous 1.0 mol L-1 NH(3)-2.0x10(-4) mol L-1 AgNO3. For both non-competitive and competitive formats, calibration plots in the ranges 5.0x10(-10) to 1.0x10(-8) mol L-1 and 1.0x10(-10) to 1.0x10(-9) mol L-1 HSA, respectively, with estimated detection limits of 1.5x10(-10) mol L-1 (10 ng mL-1) and 1.0x10(-10) mol L-1 (7 ng mL-1), respectively, were obtained. Levels of HSA in two healthy volunteer urine samples were also evaluated, using both immunoassay formats.

DNA hybridization sensor based on aurothiomalate electroactive label on glassy carbon electrodes

“…The conjugation of aurothiomalate to single strands was carried out according to the procedure described in a previous work to label immunoglobulins (de la Escosura-Muñiz et al, 2004a). An aliquot of 50 L of a 200 ng L −1 target strand solution was mixed with an aliquot of 450 L of a 390 ng L −1 sodium aurothiomalate solution.…”

“…This analytical procedure, based on the catalytic effect of electrodeposited gold on the electroreduction of silver ions (de la Escosura-Muñiz et al, 2004b) has been previously optimized, using bovine serum albumin (BSA) and a rabbit immunoglobulin G (RIgG) labeled with aurothiomalate (de la Escosura-Muñiz et al, 2004a). Briefly, this detection protocol involves a reduction step at −1.00 V in HCl 0.1 M for the gold label electrodeposition on the electrode surface, followed by an oxidation step in 0.1 M H 2 SO 4 necessary to remove the hydrogen generated in the gold deposition step and to oxidize this gold.…”

“…This gold(I) complex has been previously used in our laboratory with success as electroactive label for immunosensor devices using glassy carbon electrodes (GCEs) as electrochemical transducers (de la Escosura-Muñiz et al, 2004a). This gold(I) complex has been previously used in our laboratory with success as electroactive label for immunosensor devices using glassy carbon electrodes (GCEs) as electrochemical transducers (de la Escosura-Muñiz et al, 2004a).…”

DNA hybridization biosensors using polylysine modified SPCEs

“…In this work, two electrochemical DNA hybridization sensors are developed using both the enzyme alkaline phosphate (AP) and the Au(I) complex, sodium aurothiomalate, as label. This Au(I) complex has been previously used in our laboratory with success as electroactive label for immunosensor (De la Escosura Muñiz et al, 2004a, 2006a and genosensor (De la Escosura Muñiz et al, 2007) devices using glassy carbon electrodes as transducers. The electrochemical detection in these biosensors is based on the catalytic effect of ionic gold on silver electrodeposition (De la Escosura Muñiz et al, 2004b).…”

Interface potential sensing from adsorption of human serum albumin (HSA) on carbon nanotube (CNT) monitored by zero current potentiometry for HSA determination

“…Various strategies for immobilizing antibody or antigen at the electrode surface, accomplishing appropriate immunoreaction and subsequently electrochemical detection were cleverly integrated. Electrochemical technique used included the current detection by voltammetry (de la Escosura-Muniz et al, 2006;Omidfar et al, 2011;Akter et al, 2013), impedance detection (Sargent et al, 1999;Dawan et al, 2013) and capacitance detection by EIS (Mirsky et al, 1997) and so on. These immunosensors have high sensitivity and excellent specificity, and bear the potential for the clinic applications.…”