Preparation of Inorganic Nanoparticles for Sensor and Bioapplications

Farooq, Asima (2013) Preparation of Inorganic Nanoparticles for Sensor and Bioapplications. Doctoral thesis (PhD), Manchester Metropolitan University.

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Abstract

A wide variety of silica based nanoparticles (NPs) were synthesised to engineer materials with properties for specific applications by manipulating the nanoparticle composition. These include luminescent core shell NPs and luminescent mesoporous silica which have been successfully synthesised. The particle size distribution and characteristics of the NPs were determined by photon correlation spectroscopy. The laser Doppler velocimetry was used to determine the NPs stability in suspension. Transmission and scanning electron microscopy analysis were used to assess morphology and size of the NPs. Diffuse reflectance infra-red Fourier transform spectroscopy was used to study the template removal to produce porous NPs. The particles were then utilized for assessing different applications. A novel dual oxygen (O2) and sulphur dioxide (SO2) gas sensor was produced by incorporating fluorophores within SiNPs. The fluorophore rhodamine B isothiocyanate (RBITC) was encapsulated within SiNPs (208±9 nm) to produce a nanosensor that is sensitive to SO2, while ruthenium-tris(4,7-diphenyl-1,10-phenanthroline) dichloride (Ru(dpp)3) was encapsulated within SiNPs (192±8 nm) to sense O2. The sensor utilises the fluorescence quenching phenomena as a detection mechanism and had high sensitivity for detection of low O2 gas concentrations (0.018 %). These novel nanosensors demonstrate potential to develop multisensor systems to capable of detecting multiple gasses simultaneously in a single matrix for a magnitude of future applications that require small robust gas sensing. Biocompatibility of SiNP number, size (smaller than 100 nm), and dye encapsulation on conduit arterial function, in vitro was assessed. Their effects on endothelial-dependent [acetylcholine (ACh); 0.01-200 M] and independent [sodium nitroprusside (SNP); 0.001-10 M] dilator responses were examined. When incubated with 1.96×1012 NP/ mL, both 30 nm, 70 nm SiNPs and RBITC encapsulated in silica nanoparticles (SiRBITC NPs) significantly reduced endothelium-dependent, but not independent vasodilation. Furthermore, attenuated dilation due to SiRBITC NPs, but not SiNPs, could be partially restored using superoxide dismutase. Our results suggest that the mechanism of attenuated dilation is different for SiNPs and SiRBITC NPs which has implications for the future fabrication of biocompatible nanoparticles for imaging diagnostics. Spherical mesoporous nanoparticles (MNP) and dye encapsulated MNP were synthesised via a sol-gel method in XXIII the presences of organic template. The template was removed using an acidic extraction. The average diameters of the MNP were 100 nm. The interior pores were loaded with SNP, these drug loaded MNP were placed in live tissue and release in real-time was observed, in vitro. We demonstrate that the initial instantaneous release is due to the surface adsorption of the drug followed by released from the pores. Furthermore, these drug loaded MNP were placed in live tissue and release in real-time was observed, in vitro.