Electroaddressed immobilization of recombinant HIV-1 P24 capsid protein onto screen-printed arrays for serological testing

A serological chemiluminescent biochip was designed based on screen-printed electrode arrays composed of nine 1-mm2 electrodes. Arrays were shown to be produced with good batch-to-batch reproducibility (standard deviations of 4.4 and 12.0% for ferricyanide oxidation potential and current, respectively) and very good reproducibility within a particular array (2.0 and 7.5% standard deviations for the same controls). Electrode arrays were used to electroaddress various bioconjugate structures comprising a recombinant HIV-1 P24 capsid protein (RH24K) in polypyrrole film. Entrapment of RH24K preimmobilized onto maleic anhydride-alt-methyl vinyl ether copolymer was shown to be the more efficient immobilization procedure. This addressed sensing layer enabled the detection of anti-P24 antibodies at a concentration of 3.5 ng/ml through peroxidase-labeled anti-human immunoglobulin G reaction. The biochip was used to perform an HIV-1 serological test in human sera. HIV-1 seropositive and seronegative sera were easily discriminated using serum dilutions greater than 1/10,000.