Gene Diagnosis Using DNA-Linked Colloidal Nanoparticles

The graft copolymer consisting of poly(N-isopropylacrylamide) (PNIPAAm) and single-stranded DNA was found to form nanoparticles above physiological temperature. We found that non-crosslinking aggregation of the DNA-PNIPAAm nanoparticles was induced by the hybridization of the surface DNA with the full-match complementary DNA. We showed that this novel aggregation mechanism was applicable for the target 24mer DNA corresponding to k-ras (oncogene) codon 10-17 as well as for SNP sites of CYP2C9. Each nanoparticle aggregated by the hybridization with its full-match complementary DNA fragment, but not with one-base mismatch. These results demonstrated that the non-crosslinking aggregation of DNA- PNIPAAm nanoparticles is useful for analyzing various SNPs.

Single Nucleotide Polymorphisms Assay Using DNA-Linked Colliodal Nanoparticles

We have proven that the non-crosslinking aggregation is not a unique property of the DNA-PNIPAAm system. It also occurs with DNA-modified gold nanoparticles. The aggregation can be detected by colorimetric change of the colloidal solution into purple. The nanoparticles aggregate together when the probe DNA is hybridized with fully complementary DNA. In contrast, the terminal-mismatched DNA did not cause any discernible change. The non-crosslinking aggregation has unusual sensitivity for single-base mismatch at the terminus opposite to the anchored side.

Single-base Mutation Detection Using gold Nanoparticle Aggregation

References

(1)	Sato K., Onoguchi M., Sato Y., Hosokawa K., and Maeda M.; “Non-cross-linking gold nanoparticle aggregation for sensitive detection of single-nucleotide polymorphisms: Optimization of the particle diameter” Anal. Biochem., 350, 162-164 (2006).
(2)	Sato K., Hosokawa K., and Maeda M.; “Non-cross-linking gold nanoparticle aggregation as a detection method for single-base substitutions” Nucleic Acids Research, 33, 1, e4 (2005).
(3)	Mori T. and Maeda M.: “Temperature-responsive formation of colloidal nanoparticles from poly(N-isopropylacrylamide) grafted with single-stranded DNA” Langmuir 20, 313-319 (2004).
(4)	Tang Z. L., Takarada, T., Sato Y., and Maeda M.: “Colloidal nanoparticles from poly(N-isopropylacrylamide)-graft-DNA for single nucleotide discrimination based on salt-induced aggregation: extension to long target DNA” Chem. Lett. 33, 1602-1603 (2004).
(5)	Sato K., Sawayanagi M., Hosokawa K., and Maeda M.: "Single-base mutation detection using neutravidin-modified polystyrene nanoparticle aggregation." Anal. Sci. 20, 893-894 (2004).
(6)	Sato, K., Hosokawa, K., and Maeda, M.: "Rapid aggregation of gold nanoparticles induced by non-cross-linking DNA hybridization" J. Am. Chem. Soc. 125 (27), 8102-8103 (2003).
(7)	Mori T. and Maeda M.: “Stability Change of DNA-Carrying Colloidal Particle Induced by Hybridization with Target DNA” Polym. J. 34, 624-628, (2002).
(8)	Tang Z. L., Mori T., Takarada T., and Maeda M.: “Single Nucleotide Polymorphisms (SNPs) Assay Using Reversible Association and Dispersion of DNA-Linked Colloidal Nanoparticles” Nucleic Acids Res. Suppl. 1, 165-166, (2001).
(9)	Tang Z. L., Mori T., Takarada T., and Maeda M.: “Recognition of DNA Sequence and Chain Length by Using DNA-Linked Nanoparticle” Anal. Sci. Supple. 17, a357-a359, (2001).

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