Porphyrin-magnetite nanoconjugates for biological imaging

<p>Background: The use of silica coated magnetic nanoparticles as contrast agents has resulted in the production of highly stable, non-toxic solutions that can be manipulated via an external magnetic field. As a result, the interaction of these nanocomposites with cells is of vital importance in understanding their behaviour and biocompatibility. Here we report the preparation, characterisation and potential application of new “two-in-one” magnetic fluorescent nanocomposites composed of silica-coated magnetite nanoparticles covalently linked to a porphyrin moiety.</p> <p>Method: The experiments were performed by administering porphyrin functionalised silica-coated magnetite nanoparticles to THP-1 cells, a human acute monocytic leukaemia cell line. Cells were cultured in RPMI 1640 medium with 25 mM HEPES supplemented with heat-inactivated foetal bovine serum (FBS).</p> <p>Results: We have synthesised, characterised and analysed in vitro, a new multimodal (magnetic and fluorescent) porphyrin magnetic nanoparticle composite (PMNC). Initial co-incubation experiments performed with THP-1 macrophage cells were promising; however the PMNC photobleached under confocal microscopy study. bmercaptoethanol (b-ME) was employed to counteract this problem and resulted not only in enhanced fluorescence emission, but also allowed for elongated imaging and increased exposure times of the PMNC in a cellular environment.</p> <p>Conclusion: Our experiments have demonstrated that b-ME visibly enhances the emission intensity. No deleterious effects to the cells were witnessed upon co-incubation with b-ME alone and no increases in background fluorescence were recorded. These results should present an interest for further development of in vitro biological imaging techniques.</p&gt

Effects of the surroundings and conformerisation of n-dodecane molecules on evaporation/condensation processes.

The evaporation/condensation coefficient (β) and the evaporation rate (γ) for n-dodecane vs. temperature, gas pressure, gas and liquid density, and solvation effects at a droplet surface are analysed using quantum chemical density functional theory calculations of several ensembles of conformers of n-dodecane molecules in the gas phase (hybrid functional ωB97X-D with the cc-pVTZ and cc-pVDZ basis sets) and in liquid phase (solvation method: SMD/ωB97X-D). It is shown that β depends more strongly on a number of neighbouring molecules interacting with an evaporating molecule at a droplet surface (this number is estimated through changes in the surface Gibbs free energy of solvation) than on pressure in the gas phase or conformerisation and cross-conformerisation of molecules in both phases. Thus, temperature and the surrounding effects at droplet surfaces are the dominant factors affecting the values of β for n-dodecane molecules. These values are shown to be similar (at reduced temperatures T/Tc 0.8) than the values of β calculated by the molecular dynamics force fields (MD FF) methods. This endorses the reliability of the previously developed classical approach to estimation of β by the MD FF methods, except at temperatures close to the critical temperature

New two in one magnetic fluorescent nanocomposites

Magnetite nanoparticles have been coated by a porphyrin derivative to produce new magnetic materials with fluorescent properties. The magnetic nanoparticles were prepared using two different methods, one based on sol-gel techniques and ultrasonic processing, and the other via a controlled chemical co-precipitation. Different types of porphyrin functionalised magnetic nanoparticles have been prepared and have been characterised by electron microscopy (TEM and SEM), XRD, FTIR, Raman, UV-vis, and fluorescence spectroscopy. Microscopy results showed the formation of core-shell nanostructures, with IR and photoluminescence spectroscopy results confirming the presence of porphyrin in the shell

Preparation and biological investigation of luminescent water soluble CdTe nanoparticles

In this study CdTe quantum dots have been successfully prepared in aqueous medium using several different thiol stabilizers. The resulting nanocrystals were purified and the photoluminescence efficiency was subsequently enhanced through post preparative procedures such as photochemical etching and ageing. An optical study was carried out on the resulting CdTe nanocrystals as proof as their improvement. Preliminary tests of the thiol stabilised QDs as potential biolabels have been performed. It has been shown that L-cysteine stabilised QDs localising to the outer cell membrane in living cells. TGA stabilised CdTe QDs can potentially serve as live cell imaging tools as they exhibit strong luminescence and excellent photostability. In addition, the ability of TGA stabilised CdTe QDs to traverse the cell membrane of macrophages is a formidable quality that may potentially be harnessed for imaging and therapeutics. Modulating the delivery of QDs to subcellular locations in living cells opens a myriad of potential applications ranging from drug delivery to examination of intracellular processes

Rare earth doped silica nanoparticles via thermolysis of a single source metallasilsesquioxane precursor

Rare earth metal doped silica nanoparticles have significant advantages over traditional organic dyes and quantum dots. Silsesquioxanes are promising precursors in the production of silica nanoparticles by thermolysis, due to their structural similarities with silica materials. This manuscript describes the production of a new Eu(3+)-based metallasilsesquioxane species and its use as a single source precursor in the thermolytic production of luminescent rare earth metal doped silica nanoparticles with characteristic emission in the visible region of the spectrum

In-situ optical characterisation of the spatial dynamics of liquid crystalline nanocomposites

Liquid crystalline nanocomposites are a novel class of hybrid fluid materials, which are currently attracting significant interest from the photonics community. Such fluid nano-composites are based on low-dimensional nanoparticles (carbon nanotubes, graphene, transition metal dichalcogenides (TMDCs), metal nanoparticles etc.) dispersed in a fluidic host material. Liquid crystalline properties can either be provided by using a liquid crystal host fluid, or, through the solvent-induced self-assembly of particles. They possess a unique capability to interact with light, utilising many possibilities in plasmonics and quantum optics while they can also be integrated on Si chip by means of microfluidic technology. Integration of the nanocomposites on chip allows for dynamic control of the dispersed particle ordering through the application of various external stimuli. However, this dynamic control requires a suitable characterisation technique to fully understand the time evolution of metastructure formation. Integrated nanocomposites are characterised by the particle concentration at different points on chip, while the individual particles are defined by their sizes, xyz positions and orientation relative to the chip architecture. Here, we present a method by which all the required information for complete characterisation of the system can be obtained using a single spectroscopic technique- Raman spectroscopy- and how changes in the system can then be monitored during device operation. Liquid crystalline nanocomposites have been synthesised based on two-dimensional (2D) materials including graphene oxide (GO) and TMDCs dispersed in either commercially available liquid crystals or various organic solvents. We present both numerical analysis of the theoretical practicability of the use of Raman spectroscopy to extrapolate the desired nanocomposite properties and the experimental confirmation of the achievability of these measurements for the full range of synthesised nanocomposites

Dynamic in-situ sensing of fluid-dispersed 2D materials integrated on microfluidic Si chip

This is the author accepted manuscript. The final version is available from Nature Publishing Group via the DOI in this record.The supplementary videos associated with this article are located in ORE at: https://doi.org/10.24378/exe.1643In this work, we propose a novel approach for wafer-scale integration of 2D materials on CMOS photonics chip utilising methods of synthetic chemistry and microfluidics technology. We have successfully demonstrated that this approach can be used for integration of any fluid-dispersed 2D nano-objects on silicon-on-insulator photonics platform. We demonstrate for the first time that the design of an optofluidic waveguide system can be optimised to enable simultaneous in-situ Raman spectroscopy monitoring of 2D dispersed flakes during the device operation. Moreover, for the first time, we have successfully demonstrated the possibility of label-free 2D flake detection via selective enhancement of the Stokes Raman signal at specific wavelengths. We discovered an ultra-high signal sensitivity to the xyz alignment of 2D flakes within the optofluidic waveguide, which in turn enables precise in-situ alignment detection for the first practicable realisation of 3D photonic microstructure shaping based on 2D-fluid composites and CMOS photonics platform while also representing a useful technological tool for the control of liquid phase deposition of 2D materials.We acknowledge financial support from: The Engineering and Physical Sciences Research Council (EPSRC) of the United Kingdom via the EPSRC Centre for Doctoral Training in Electromagnetic Metamaterials (Grant No. EP/L015331/1) and also via Grant Nos. EP/N035569/1, EP/G036101/1, EP/M002438/1, and EP/M001024/1, Science Foundation Ireland Grant No. 12/IA/1300, the Ministry of Education and Science of the Russian Federation (Grant No. 14.B25.31.0002) and the Royal Society International Exchange Grant 2015/R3. The microfluidic structures were fabricated at Tyndall National Institute under the Science Foundation Ireland NAP368 and NAP94 programs