Gold-on-gold Film Formation On Polydimethylsiloxane Substrates For Cyanine 5 Fluorescence Enhancement

Based on seed-growth synthesis method,gold-on-gold(Au/Au)film was coated onto the surface of polydimethylsiloxane(PDMS)substrates,which enhanced the fluorescence of Cyanine 5(Cy5).After pH modification of HAuCl4 solution by ammonium hydroxide,Au3+ was bonded on the PDMS substrates and then reduced to Au0 to form Au nanoparticles.Hydroxylamine subsequently deposited more Au3+from HAuCl4 onto Au nanoparticles to grow to Au/Au film.Atomic force microscopy(AFM),scanning electron microscopy(SEM)and fluorescent microscopy were employed to quantitatively characterize the morphology as well as fluorescence enhancement performance of Au/Au films formed under different synthesis conditions.With 5 mM HAuCl4 as seeding solution and 1000 μM HAuCl4/NH2OH as growth solution,Au islands with average area of 92784 nm2 were obtained and they covered 68.36%area of the PDMS substrate,and this Au/Au film could achieve the maximum fluorescence enhancement performance.The morphology and fluorescence enhancement of the hydrophilic glass substrates and the hydropobic PDMS substrates were compared and better performance was obtained by the hydropobic PDMS substrates.