Shrinking hydrogel-DNA spots generates 3D microdots arrays

This report describes a straightforward approach for the achievement of sub-100 micrometers size hydrogel dots supporting DNA immobilization. Hydrogel-DNA spots are arrayed and UV-crosslinked on PolyShrink, an innovative polymer material having the remarkable property of isotropically shrinking under high temperature. Curing the microarray enables then spot miniaturization, resulting in 6 µm thick and 60 µm wide hydrogel dots in which oligonucleotides are immobilized in a 3D hydrophilic environment. The probe immobilization within the hydrogel network and its capacity to detect targets specifically and quantitatively is demonstrated using chemiluminescent as well as colorimetric detection techniques. The hydrogel material improves probe accessibility within the spot, leading to an enhanced sensitivity.

PCR-product microarray based on polyacrylic acid-modified surface for SNP genotyping

PCR-product microarray has great efficiency in SNP genotyping, mutation screening and epigenetic analyzing from a large number of samples. The current PCR-product microarray technology is mostly based on the 3-D gel microarray technologies due to its high loading capacity for PCR products, while there is little progress for PCR-product microarray on planar glass, which gives low background and convenient fabrication. In this study, we improved the PCR-product microarray on planar glass by employing a polyacrylic acid-covered slide. The raw amino-modified PCR products were simply precipitated with ethanol and directly spotted for DNA immobilization. Three detection methods of hybridization, solid-single base extension and solid-multiple bases elongation were carried out for single nucleotide variation identification on the PCR-product microarray. The experimental results showed that the high immobilization yield for raw PCR product was achieved, and the high specificity and high ratio of S/N for genotyping on the microarray were obtained. SNP genotyping of cytochrome P450 2D6 gene in 30 individuals was successfully demonstrated. This study has significantly increased the performances of PCR-product microarray, which could improve its applications in SNP genotyping and mutation screening in large number of individuals.

Tag-extension-based method for sensitive and specific genotyping of single nucleotide polymorphism on microarray

BACKGROUND

The obtainment of a large amount of single nucleotide polymorphism (SNP) information has emphasized a need for a sensitive, accurate and high-throughput strategy for SNP genotyping. We developed a reliable and potential microarray-based method to meet this demand.

METHODS

A tag extension strategy is described to identify SNPs. The strategy is based on a fluorescent nucleotide extension from an extending primer that is hybridized to a bi-functional linker, which acts as an allele-specific primer that hybridizes with a PCR-amplified target DNA immobilized on a 3-dimensional (3-D) polyacrylamide gel microarray, as well as an extending template with a specific tag itself hybridized with a universal extension primer. Multiple fluorescence-dNTPs are simultaneously incorporated into the tagged linker.

RESULTS

The method not only significantly enhanced the sensitivity, but also efficiently improved the specificity of SNP genotyping. 89 samples for 8025575C/G polymorphisms in gamma-aminobutyric acid A receptor, beta 3 (GABAB3) gene were accurately discriminated using this method. Sanger sequencing was performed to validate these results.

CONCLUSION

Our experiments successfully demonstrated that a tag-extension-based method on microarray could be used as a high-throughput and useful tool to obtain SNP information.