UV-VIS extinction spectra of gold particle coated by oligonucleotide shell

摘要

We describe synthesis process of an oligonucleotide-functionalized colloidal gold marker CG-15-T_(28), its optical properties and interaction with poly(A) in solution and on a solid-phase substrate. The marker is a complex of 15 nm diameter colloidal gold nanoparticles with covalently attached 5′-thiolated 28-base oligothymidine macromolecules. A positive hybridization reaction of the marker with poly(A) is observed by solid-phase analysis on hanging a spot color (from red to blue ) or on appearance of a red dye in dot-blot test as compared to control experiments with poly(L') target. The principles of spectrophotometric monitoring all stages of the marker preparation and application of spectrophotometry to detection of the polynucleotide hybridization in vitro are described. Experimental data were compared with theoretical calculations based on Mie theory for 2-layer model of gold core in polymeric shell with imaginary part of refractive index that typical for the real absorption spectra of NA. To explain the aggregation of CG-15-T_(28) caused by interaction with poly(A) in solution, we suggest a new model differing from a standard model of cross-linker binding.