Analytical Sciences

Colorimetric Detection of Polynucleotides on Polypropylene Slices

Libo NIE,* Jianxin TANG,* Huishi GUO,* Hong CHEN,** Pengfeng XIAO,* and Nongyue HE*

*Key Laboratory of Molecular and Biomolecular Electronics (Southeast University), Ministry of Education, Nanjing 210096, China
**Life Science and Technology Department of Central South Forestry University, Changsha 410004, China

The gold-label-silver-stain method (GLSS) for DNA hybridization detection has been receiving increased interest as a colorimetric detective method, demonstrating the advantages of non-radioactivity, non-quenching effect of fluorescence and simplicity for analytical equipment. A colorimetric detection based on the GLSS method was applied to DNA arrays in situ synthesized on polypropylene (PP) slices. In this paper a simple plasma treatment was employed to graft amino (-NH₂) on the polypropylene slice surfaces, where DNA probes were immobilized via in situ synthesis. Hybridization was accomplished by a sandwich hybridization format. With the amplification of Silver Enhancer Solution, the hybridization signals were recorded with a scanner. A target DNA concentration as low as 100 fM was detected. Complementary and mismatched sequences were clearly distinguished, and the ratio of the background-subtracted gray scale values for a perfect match, single-base mismatch, 2-base mismatch and 3-base mismatch is 22:16:9:4. The sensitivity of the in situ synthesis system was 3 orders of magnitude higher than that of the spotting system, and the signals of the former were about 2-times stronger than that of the latter under the same target DNA concentration.

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