The effects of glass surfaces and probe GC content on signal intensities of a 60-mer diagnostic microarray

The effects of glass surfaces and probe GC content on signal intensities of a 60-mer diagnostic microarray were studied. Twelve virus-specific oligonucleotide probes for severe acute respiratory syndrome coronavirus (SARS-CoV) were divided into a high GC content group (≥ 50%) and a low GC content group (< 50%), and spotted onto four different chemically-modified glass surfaces: a poly-amine coating activated by 1,4-phenylene diisothiocyanate (Poly-Amine surface), an acrylic acid-co-acrylamide copolymer coating activated by 1-(3-dimethylamino propyl)-3-ethylcarbodiimide hydrochloride and N-hydroxysuccinimide (AACA-Copolymer surface), a commercial Corning CMT-GAPS amino surface, and a Telechem SuperAmine amino surface. RNA samples from cultured SARS-CoV strain were labelled using direct cDNA labelling with restriction display in a single colour format. The background-subtracted signal intensities were analysed using two-way analysis of variance. The effects of glass surfaces on background-subtracted signal intensities were significant (p=0.003). Multiple comparisons showed that differences existed mainly between the AACA-Copolymer surface and the other glass surfaces, and that the AACA-Copolymer surface had the highest background-subtracted signal intensity. The probe GC content had no significant effect on signal intensities in the narrow range of GC content represented (p=0.07). The results suggested that the AACA-Copolymer surface may be a novel choice of microorganism survey based on long oligonucleotide microarray.