Plasma Immersion Ion Implanted Polymers for Antibody Microarray Applications

Abstract

A novel platform for protein microarrays with improved sensitivity and reproducibility was developed. Plasma immersion ion implantation (PIII) treated polycarbonate (PC) was used as a substrate for anti-cluster of differentiation (CD) antibody microarrays. Compared to the current industrial standard, nitrocellulose-coated glass slides, the novel platform requires a three times lower concentration of anti-CD antibodies to achieve an equivalent signal strength and has about two times better reproducibility and three times higher sensitivity. For the first time, an anti-CD antibody microarray was used to directly observe the reaction of living human white blood cells to foreign antibodies. It was shown that anti-CD antibody microarrays can be successfully used to test for patient specific cross-reactivity and hemotoxicity of therapeutic antibodies. To select the most suitable parameters of PIII treatment, the kinetics of free radicals formed in polystyrene (PS) during PIII treatment was studied. The rates of free radical decay were determined. Post-treatment oxidation of PIII treated PS has shown a close relationship of oxidation kinetics to the free radical kinetics. Both oxidation and hydrophobic recovery had two stages with characteristic times of several hours and several days. The time of PIII treatment of PC slides was selected taking into account protein binding capacity, wettability, surface chemistry and transparency of the PIII treated PC. The effect of untreated and PIII treated surfaces on the conformation and orientation of anti-CD34 antibody was studied. It was shown that the conformation of the antibody was better preserved on the PIII treated surface than on untreated one. Also, compared to untreated PC, a larger fraction of the antibody immobilized on PIII treated PC had an orientation optimal for antigen binding.