Luminescent ruthenium(II) tris-bipyridyl complex caged in nanoscale silica for particle velocimetry studies in microchannels

Abstract

Luminescence and imaging studies of 500 nm diameter colloidal silica stained with the transition metal complex [Ru(bpy)3Cl2], [Ru(bpy)3⊂SiNP], have been detailed and suggest that such particles are ideal for particle tracking velocimetry (PTV) or particle imaging velocimetry (PIV) for analysis of fluid flow in microchannels. Silica particles were synthesized using a modification to the Stöber synthesis to cage the transition metal complex within the core of the nanoscale particles. The particles [Ru(bpy)3⊂SiNP] exhibit luminescence at 620 nm, characteristic of the caged [Ru(bpy)3]2+ species with a lifetime of 790 ns upon excitation at 450 nm. A collection of the luminescence spectra from the images of the particles in a microchannel have the same profile as the spectra collected from solutions of [Ru(bpy)3⊂SiNP], confirming that the luminescence images are attributed to [Ru(bpy)3]2+ luminescence. PIV and PTV measurements from image sequences give flow velocities that match well with the theoretical velocity profile for a rectangular-sided microchannel of 100 µm depth.

A Label-Free Microfluidic Biosensor for Activity Detection of Single Microalgae Cells Based on Chlorophyll Fluorescence

“…Microfluidic chips or Labs-on-a-Chip (LOCs) are a promising technique for fast in situ detection of small amounts of samples. They are applied widely in chemistry, biology, medicine and the environment [ 12 – 23 ]. In recent years, impedance methods based on the Coulter principle have been used in LOC for detecting all kinds of microparticles [ 24 – 26 ].…”

The deposition and imaging of silica sub-micron particles in dentine

“…The silica particles used in this project have a porous structure and therefore have the potential to be a carrier for a range of molecules including calcium based compounds. These particles may also serve as a carrier for antimicrobial compounds and therefore offer a novel approach to treating contaminated hard tissues (16,17).…”

“…The properties of this preparation are such that the particles achieve suitable interaction with the surface and clustered to achieve optimum tubule occlusion, compared to the other preparations investigated. The use of luminescent particles also provides an avenue for the use of luminescence imaging to investigate their use on dental surfaces (17).…”

“…The particles used in this investigation consisted of spherical silica encapsulated with a luminescent complex, tris-(2,2'-bipyridyl) ruthenium(II) dichloride, represented as SiO2-Ru 17 , with a size of 640nm were designated as SiO2-Ru-640 (640±90 nm). The effect of polymer coating did not change the size within the error limit of the particle size analysed.…”

Penetration of sub-micron particles into dentinal tubules using ultrasonic cavitation

“…In this study we used silica (SiO2) sub-micron particles prepared in the same manner as those used by Claire et al to compare the effect of the cavitation and acetone addition on the particle distribution on the dentine surface. The silica particles were prepared according to a published method [16] containing a luminescent ruthenium complex (tris-(2,2'bipyridyl)ruthenium(II) dichloride) for introducing a luminescent core for potential luminescence imaging. Dynamic Light Scattering (DLS) was used to estimate the particle size distribution (Zetasizer Nano ZSP, Malvern Instruments, UK).…”