Here, a three-dimensional (3D) oligonucleotide microarray-based fluorescent assay has been developed for single nucleotide polymorphisms (SNPs) and allele frequency determination. The 3D oligonucleotide microarray is fabricated on a home-made polyacrylamide hydrogel microarray which is generated by UV light photopolymerization of tiny acrylamide monomer droplets on a PEG terminated glass slide. After activation by glutaraldehyde (GA), the polyacrylamide hydrogel is able to react with NH2-modified oligonucleotides with high efficiency to generate a high signal-to-background ratio without the conventional blocking step. We demonstrate that the assay is able to detect complimentary 25 mer oligonucleotide target (fragment of a tumor suppressor gene P53) down to 100 pM and SNP with true-to-false ratios (the ratio of fluorescence signal from perfect matched DNA strands to that from the one-base mismatched DNA strands) above 20. Taking advantage of the high specificity of the assay, allele frequency as low as 2% can be accurately determined.

Here, a three-dimensional (3D) carbohydrate microarray-based plasmon resonance light scattering (RLS) assay has been established for studying carbohydrate–lectin binding with high selectivity. The 3D carbohydrate microarray is fabricated by immobilizing amino-modified carbohydrates on the home-made fourth-generation (G4) NH2-terminated poly(amidoamine) dendrimers (PAMAM)-modified substrate. After marking the carbohydrate–lectin binding events by 13 nm peptide-stabilized gold nanoparticles through the biotin–avidin reaction, the 3D microarray can be directly detected by the RLS scanner without the conventional silver enhancement step. The well defined recognition systems: three monosaccharides (Man-α, Glc-α and Gal-β) with two lectins (Con A and RCA 120), have been chosen here to establish the RLS assay, respectively. Quantitative determination of the surface dissociation constants (KD,surf) for surface carbohydrates and lectins has been achieved. In addition, inhibition values (i.e. the inhibition constants (Ki) and the concentrations of inhibitors required to produce 50% inhibition (IC50)) for inhibitors in solution are also demonstrated by the saccharide competing assays.

Here, a three-dimensional (3D) oligonucleotide microarray-based fluorescent assay has been developed for single nucleotide polymorphisms (SNPs) and allele frequency determination. The 3D oligonucleotide microarray is fabricated on a home-made polyacrylamide hydrogel microarray which is generated by UV light photopolymerization of tiny acrylamide monomer droplets on a PEG terminated glass slide. After activation by glutaraldehyde (GA), the polyacrylamide hydrogel is able to react with NH2-modified oligonucleotides with high efficiency to generate a high signal-to-background ratio without the conventional blocking step. We demonstrate that the assay is able to detect complimentary 25 mer oligonucleotide target (fragment of a tumor suppressor gene P53) down to 100 pM and SNP with true-to-false ratios (the ratio of fluorescence signal from perfect matched DNA strands to that from the one-base mismatched DNA strands) above 20. Taking advantage of the high specificity of the assay, allele frequency as low as 2% can be accurately determined.