Electrochemiluminescent Metallopolymer−Nanoparticle Composites: Nanoparticle Size Effects

摘要

Metallopolymer-gold nanocomposites have been synthesizednin which the metal complex-Au nanoparticle (NP) mole ratio isnsystematically varied by mixing solutions of 4-(dimethylamino) pyridinenprotected gold nanoparticles and a [Ru(bpy)2PVP10]2þ metallopolymer;nbpy is 2,20-bipyridyl and PVP is poly-(4-vinylpyridine). The impact ofnchanging the gold nanoparticle diameter ranging from 4.0 ( 0.5 to 12.5 (n1 nm has been investigated. The photo induced emission of the metallopolymernundergoes static quenching by the metal nanoparticles irrespectivenof their size. When the volume ratio of AuNP-Ru is 1, the quenching efficiency increases from 38% to 93% on going from 4.0(n0.5 to 12.5 ( 1 nm diameter nanoparticles while the radius of the quenching sphere remains unaffected at 75 ( 5 Å. Thenconductivity of thin films is initially unaffected by nanoparticle incorporation until a percolation threshold is reached at a mole rationof 4.95 u0002 10-2 after which the conductivity increases before reaching a maximum. For thin films of the nanocomposites onnelectrodes, the electrochemiluminescence intensity of the nanocomposite initially increases as nanoparticles are added beforendecreasing for the highest loadings. The electrochemiluminescence intensity increases with increasing nanoparticle diameter. Thenelectrochemiluminescence (ECL) emission intensity of the nanocomposite formed using 12.5 nm particles at mole ratios betweenn5 u0002 10-3 and 10 u0002 10-3 is approximately 7-fold higher than that found for the parent metallopolymer. The application of thesenmaterials for low cost ECL-based point of care devices is discussed.