Colorimetric Detection
Bryce Nelson, Ph.D., vp, R&D at Gentel Biosciences, discussed the need for a workable and affordable multiplexed protein detection system designed around a traditional ELISA format.
“Our focus is to make protein arrays accessible to laboratories currently using ELISA technology,” Dr. Nelson stated. Gentel explores the familiar goal of disease biomarker discovery aimed toward validation through clinical trials using nitrocellulose surface platforms. Such markers could monitor therapeutic interventions and identify new therapeutic targets.
The microarrays are evaluated using either a fluorescence-based or a colorimetric-based assay system. For fluorescent determination Gentel uses PATH® Protein Microarray Slides, composed of transparent nitrocellulose on glass substrates and formatted in standard microarray slide and 96-well format. Alternatively, for colorimetric determination, the APiX™ Protein Microarray Slides use transparent nitrocellulose on plastic or glass substrates.
The system is compatible with Gentel’s forthcoming APiX Colorimetric Reader and detection reagents, and both systems can be automated. Subsequent investigations demonstrated that the colorimetric assay system is quite sensitive, can multiplex several hundred protein in a well, and can read plates in minutes by a simple, low cost reader, Dr. Nelson reported.
The APiX colorimetric system uses a gold particle-enhanced silver deposition technology that is “basically a silver stain for microarrays. We have shown that the system yields higher sensitivity than bead-based and fluorescence-based microarrays,” he added.
Gentel has used the APiX colorimetric system in conjunction with antibody array methods to screen serum protein glycosylation changes in hundreds of proteins as potential cancer biomarkers. The APiX GlycoBiomarker array kit, designed for the characterization of disease-associated glycan alterations, is used for the identification of new biomarkers and the analysis of factors that regulate glycan structures.
Dr. Nelson and his colleagues at Gentel have also validated the performance of the APiX colorimetric system using a number of different array formats, including Eprogen’s multidimensional liquid-phase protein fractionation system. “As these technologies mature, there will be a need for an affordable multiplex protein detection format for diagnostics that doesn’t sacrifice performance,” Dr. Nelson added. “We believe the features of our gold particle-enhanced silver deposition platform move us closer to this goal.”