Quantitative detection of C-reactive protein using phosphocholine-labelled enzyme or microspheres

Abstract

C-reactive protein (CRP) is a positive, acute-phase protein. Plasma levels rise dramatically in response to tissue injury or inflammation and fall rapidly after recovery or treatment. Antibody-based human CRP test systems do not readily detect CRP from other animals due to the species specificity of antibodies directed against human CRP. Thus, generic systems for CRP detection, based solely on the interaction between CRP and phosphocholine (PC), have been developed. PC-bovine serum albumin (PC-BSA) conjugates were produced and either labeled with horseradish peroxidase to facilitate CRP detection in a CRP enzyme-linked sorbent assay (ELSA) or coupled to carboxy-modified microspheres to facilitate the nonenzymatic, turbidimetric detection of CRP. The CRP-ELSA is a competitive assay, where the total assay time is 45 min, the assay sensitivity is 1.06 mg/L CRP, and the dynamic range of the assay is 0-500 mg/L. When PC-BSA conjugate is covalently coupled to carboxylated microspheres, agglutination occurs in the presence of CRP, the extent of which depends on the quantity of CRP present in the sample. Total assay time is 5 min with a dynamic range of 25-500 mg/L. Both assay formats are capable of accurately detecting human CRP and the CRP-ELSA can detect canine CRP as a disease state indicator.

A new turbidimetric method for assaying serum C-reactive protein based on phosphocholine interaction

“…Therefore, the development of an affordable non-immunological method for CRP assay could also be applied for veterinary purposes (9,10).…”

A new high-sensitive nephelometric method for assaying serum C-reactive protein based on phosphocholine interaction

“…Calcium-mediated CRP binding to phosphocholine has been the subject of several studies, using different reagents such as synthetic globular polymers as scaffolds for the phosphocholine molecules, or soy oil emulsions [11][12][13]. Both in vitro and in vivo, CRP has been reported to produce agglutination ('creaming') of the intravenously administered lipid suspension Intralipid [14,15].…”

Aptamer–antibody on-chip sandwich immunoassay for detection of CRP in spiked serum

“…One well-established and effective method for detecting immunoproteins, such as CRP, is based on the colloidal agglutination of antibody-coated particles upon addition of the antigen (Watkin et al, 2007;Deegan et al, 2003;Ortega-Vinuesa et al, * Corresponding author. Tel.…”

“…The assay principle is usually based on the formation of an antibody-antigen complex. Moreover, alternative approaches have been recently reported, such as those relying on the interaction between phosphocholine and CRP (Deegan et al, 2003;Roper et al, 2006), on the use of a chemically modified thermoresponsive copolymer (Raj et al, 2007) or on a CRP-reactive aptamer (Bini et al, 2008;Kim et al, 2004).…”