Luminescent Gold Surfaces for Sensing and Imaging: Patterning of Transition Metal Probes

Abstract

Luminescent transition metal complexes are introduced for the microcontact printing of optoelectronic devices. Novel ruthenium(II), RubpySS, osmium(II), OsbpySS, and cyclometalated iridium(III), IrbpySS, bipyridyl complexes with long spacers between the surface-active groups and the metal were developed to reduce the distance-dependent, nonradiative quenching pathways by the gold surface. Indeed, surface-immobilized RubpySS and IrbpySS display strong red and green luminescence, respectively, on planar gold surfaces with luminescence lifetimes of 210 ns (RubpySS·Au) and 130 and 12 ns (83%, 17%) (IrbpySS·Au). The modified surfaces show enhancement of their luminescence lifetime in comparison with solutions of the respective metal complexes, supporting the strong luminescence signal observed and introducing them as ideal inorganic probes for imaging applications. Through the technique of microcontact printing, complexes were assembled in patterns defined by the stamp. Images of the red and green patterns rendered by the RubpySS·Au and IrbpySS·Au monolayers were revealed by luminescence microscopy studies. The potential of the luminescent surfaces to respond to biomolecular recognition events is demonstrated by addition of the dominant blood-pool protein, bovine serum albumin (BSA). Upon treatment of the surface with a BSA solution, the RubpySS·Au and IrbpySS·Au monolayers display a large luminescence signal increase, which can be quantified by time-resolved measurements. The interaction of BSA was also demonstrated by surface plasmon resonance (SPR) studies of the surfaces and in solution by circular dichroism spectroscopy (CD). Overall, the assembly of arrays of designed coordination complexes using a simple and direct μ-contact printing method is demonstrated in this study and represents a general route toward the manufacture of micropatterned optoelectronic devices designed for sensing applications.

Physico-Chemical Condition Optimization during Biosynthesis lead to development of Improved and Catalytically Efficient Gold Nano Particles

“…In the rapidly growing area of nanomaterial research, gold nanoparticles have entered into a new arena, opening new possibilities in catalysis 1 , diagnostics and biomedicine 2 , optics 3 12 , imaging 4 , electronics 13 , sensing 5 6 , and agriculture 7 . The functions of gold nanoparticles heavily rely upon their structure, size and morphology, so finding a way to modulate nanoparticles biosynthesis is an important aspect of the research 8 9 10 .…”

Highly luminescent gold nanoparticles: effect of ruthenium distance for nanoprobes with enhanced lifetimes

“…The enhancement of the RuS12 complex on the AuNP is significantly larger than that of RuS1 and RuS6, even though the effect of the Zonyl surfactant is less pronounced than in RuS6. 22 It is not surprising than for the AuNP, the enhancement can be observed at this distance based on the nanoparticle induced characteristics It is expected that the closer the luminescent probe is to the surface, the larger the quenching effect.…”

“…22 Luminescence lifetime experiments were carried out using an Edinburgh Instruments EPL-445 laser as the excitation source. UV−vis spectra were collected using 1 cm path length quartz cuvettes.…”

“…20 In our approach the fluorosurfactant coating of the particles has shown to have an effect of protecting the ruthenium probe excited state from quenching by oxygen, increasing the lifetime of the complex on the nanoparticles. 16,22,23 We have also varied the size of the AuNP to examine if there is an influence on the luminescence lifetime of the probes. 21 In this study we examine the effect of the luminescence of the ruthenium probe by varying the distance of the attachment of the probe to the surface of the AuNP.…”

Surfactant‐Enhanced Luminescence Lifetime for Biomolecular Detection on Luminescent Gold Surfaces Decorated with Transition Metal Complexes

“…We have previously introduced transition metal complexes with long tethers MbpySS M=Ru, Ir, Os for attachment to gold. The complexes formed luminescent monolayers on gold surfaces as the long tethers positioned the luminescent probe further away from the gold surface which has been shown to quench luminescence emission of transition metal complexes . It was also reported that the ruthenium and iridium metal complexes could be assembled in a controlled manner through micropatterning techniques, forming red and green luminescent patterns upon stamping the surface .…”