Te. Campbell et al., Incorporation of erythrocytes into polypyrrole to form the basis of a biosensor to screen for Rhesus (D) blood groups and rhesus (D) antibodies, ELECTROANAL, 11(4), 1999, pp. 215-222
Antibodies to Rhesus (Rh) antigens are important indicators in screening fo
r haemolytic disease of the new-born (HDN) and autoimmune haemolytic anaemi
a (AIHA). Identification of the Rh antibodies formed by immune stimulation
is also essential in order to maximize the in vivo survival rime of transfu
sed erythrocytes. Currently this is performed by agglutination based assays
that are time consuming.
A prototype of an immuno-biosensor for detecting antibodies recognizing the
Rhesus blood group antigen, Rh (D), was constructed. Human erythrocytes we
re incorporated into a conducting polypyrrole, polyelectrolyte matrix. The
process was followed by using oximetry and light microscopy to demonstrate
the integrity of the erythrocytes in the polymerization solution and in the
polymer matrix; cyclic voltammetry and resistometry for electrochemical ch
aracterization of the polymer and then agglutination, ELISA techniques and
cyclic resistometry for analysis of the immune response from antigen/antibo
dy binding. Antigen/antibody binding could be detected qualitatively by usi
ng resistometry while cycling the polymer between +0.35V and -0.7V (vs. Ag/
AgCl). A characteristic cyclic change in resistance (a resistogram) was rec
orded. After addition of Anti-Rh (D) antibody (250 mu g/mL), the change in
resistance during the resistogram decreased by 1.1 Omega(p < 0.0008) in pol
ymers containing Rh (D) positive erythrocytes, whereas polymers without ery
throcytes showed no significant change.