November 2023
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11 Reads
Polyhedron
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November 2023
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11 Reads
Polyhedron
January 2023
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2 Reads
May 2019
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31 Reads
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5 Citations
Chemical Communications
Climate change necessitates the need for new renewable energy technologies. Luminescent solar concentrators (LSCs) could decrease the cost of solar photovoltaic (PV) systems. However highly fluorescent dyes suffer from high levels of reabsorption, compounding losses. We explore the covalent attachment of three organic chromophore ligands (an anthracene carboxylic acid and two perylene diimide carboxylic acids) to silicon dioxide nanoparticles. This allows us to study inter-ligand energy transfer when attached to SiO2 nanoparticles, since these cannot couple to the wide-bandgap silicon dioxide, creating a simple system with a large ratio of donors to acceptors – reducing reabsorption. Using steady-state and transient spectroscopy measurements we quantify this energy transfer between ligands. We show a maximum transfer efficiency of 30% and measure the 2D diffusion length of anthracene carboxylic acid on SiO2 to be between 0.6 and 2.2 nm. This study proves the feasibility of a new approach to increasing LSC efficiency with cheap and scalable chemistry.
January 2019
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252 Reads
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34 Citations
Indium phosphide quantum dots (QDs) passivated with zinc sulphide in a core/shell architecture (InP/ZnS) with different surface chemistries were introduced to RAW 264.7 murine “macrophage-like” cells to understand their potential toxicities. The InP/ZnS quantum dots were conjugated with an oligonucleotide, a carboxylic acid, or an amino-polyethylene glycol ligand, and cell viability and cell proliferation were investigated via a metabolic assay. Membrane integrity was measured through the production of lactate dehydrogenase. Fluorescence microscopy showed cellular uptake. All quantum dots exhibited cytotoxic behaviour less than that observed from cadmium- or lead-based quantum dots; however, this behaviour was sensitive to the ligands used. In particular, the amino-polyethylene glycol conjugated quantum dots proved to possess the highest cytotoxicity examined here. This provides quantitative evidence that aqueous InP/ZnS quantum dots can offer a safer alternative for bioimaging or in therapeutic applications.
October 2018
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11 Reads
October 2018
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219 Reads
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27 Citations
Sensors
Quantum dots are attractive alternatives to organic fluorophores for the purposes of fluorescent labeling and the detection of biomarkers. They can also be made to specifically target a protein of interest by conjugating biomolecules, such as antibodies. However, the majority of the fluorescent labeling using quantum dots is done using toxic materials such as cadmium or lead due to the well-established synthetic processes for these quantum dots. Here, we demonstrate the use of indium phosphide quantum dots with a zinc sulfide shell for the purposes of labeling and the detection of exosomes derived from the THP-1 cell line (monocyte cell line). Exosomes are nano-sized vesicles that have the potential to be used as biomarkers due to their involvement in complex cell processes. However, the lack of standardized methodology around the detection and analysis of exosomes has made it difficult to detect these membrane-containing vesicles. We targeted a protein that is known to exist on the surface of the exosomes (CD63) using a CD63 antibody. The antibody was conjugated to the quantum dots that were first made water-soluble using a ligand-exchange method. The conjugation was done using carbodiimide coupling, and was confirmed using a range of different methods such as dynamic light scattering, surface plasmon resonance, fluorescent microscopy, and Fourier transform infrared spectroscopy. The conjugation of the quantum dot antibody to the exosomes was further confirmed using similar methods. This demonstrates the potential for the use of a non-toxic conjugate to target nano-sized biomarkers that could be further used for the detection of different diseases.
September 2018
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60 Reads
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26 Citations
Bioconjugate Chemistry
Research over the past decade has identified several of the key limiting features in multidrug resistance (MDR) cancer ther-apy applications, such as evolving glycoprotein receptors at the surface of the cell that limit therapeutic uptake, metabolic changes leading to protection from multidrug resistant mediators by enhanced degradation or efflux of therapeutics, and difficulty ensuring retention of intact and functional drugs once endocytosed. Nanoparticles have been demonstrated to be effective delivery vehicles for a plethora of therapeutic agents and, in the case of nucleic acid-based agents, they provide protective advantages. Functionalizing cell penetrating peptides (CPPs), also known as protein transduction domains, onto the surface of a fluorescent quantum dots creates a labelled delivery package to investigate the nuances and difficulties of drug transport in MDR cancer cells for potential future clinical applications of diverse nanoparticle therapeutic delivery strategies. In this study, eight distinct cell penetrating peptides were used (CAAKA, VP-22, HIV-TAT, Ku-70, and hCT(9-32), integrin-β3, HIV-gp41, and K-FGF) to examine the different cellular uptake profiles in cancer versus drug resistant melano-ma (A375 & A375-R), mesothelioma (MSTO & MSTO-R), and glioma (rat 9L & 9L-R, and human U87 & LN18), cell lines. The results of this study demonstrate that cell penetrating peptide uptake varies with the amount of drug resistance and cell type, likely due to changes in cell surface markers. This study provides insight to developing functional nanoplatform deliv-ery systems in drug resistant cancer models.
April 2018
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100 Reads
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43 Citations
Nanoscale
The synthesis of colloidal indium phosphide quantum dots (InP QDs) has always been plagued by difficulties arising from limited P3− sources. Being effectively restricted to the highly pyrophoric tris(trimethylsilyl) phosphine (TMS3P) creates complications for the average chemist and presents a significant risk for industrially scaled reactions. The adaptation of tris(dialkylamino) phos- phines for these syntheses has garnered attention, as these new phosphines are much safer and can generate nanoparticles with competitive photoluminescent properties to those from (TMS)3P routes. Until now, the reaction mechanics of this precursor were elusive due to many experimental optimizations, such as the inclusion of a high concentration of zinc salts, being atypical of previous InP syntheses. Herein, we utilize density functional theory calculations to outline a logical reaction mechanism. The aminophosphine precursor is found to require activation by a zinc halide before undergoing a disproportionation reaction to self-reduce this P(III) material to a P(-III) source. We use this understanding to adapt this precursor for a two-pot nanoparticle synthesis in a nonco- ordinating solvent outside of glovebox conditions. This allowes us to generate spherical InP/ZnS nanoparticles possessing fluorescent quantum yields >55% and lifetimes as fast as 48 ns, with tunable emission according to varying zinc halide acidity. The development of high quality and efficient InP QDs with this safer aminophosphine under simple Schlenk environments will enable a broader range of researchers to synthesize these nontoxic materials for a variety of high-value applications.
January 2018
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75 Reads
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3 Citations
September 2017
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122 Reads
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29 Citations
ACS Sustainable Chemistry & Engineering
... The cytotoxicity study was performed with the silver lixiviation aliquots (extractions) as described above and using the AlamarBlueTM method. Cytotoxicity was found by calculating the percentage of live cells after their exposure to the different extractions [31,32]. ...
January 2019
... Typical emission spectra resulted from 3 scans of 0.2 s dwell time each, utilising moderate excitation (Δλ = 1 − 4 nm) and fine emission (Δλ < 0.5 nm) bandwidths, optimising peak signal to ∼700,00 counts per second (cps) with sample optical density of less than 0.1 au at the excitation wavelength. Quantum yields for these QDs have been previously measured [14,19,20]. ...
October 2018
Sensors
... As underlined before, MDR of cancer cells is a major concern in all nanohybrid-based treatment strategies. Regarding the administration of functionalized QDs, the uptake of the fluorescent nanocarriers has been reported to differ depending on the drug-resistance profile of the cells [203]. Thus, the application of nanocarriers that are superior emitters for cell labeling and two-photon imaging may be considered, such as the recently described 2D cadmium chalcogenide nanoplatelets that display a 10 times greater two-photon absorption coefficient and better fluorescence response than QDs [204]. ...
September 2018
Bioconjugate Chemistry
... Thus, since temperature accelerates reactions, faster degradation of 1.5M oxalic acid solution occurred during the synthesis of FeC2O4·2H2O at 135 °C than at 115 °C, as indicated by the pressure profiles in Figure 1c. In addition to the classical nucleation theory, the critical supersaturation (S c ) phenomenon and the nucleation rate at the S c have been more recently reported [34,35]. The S c refers to the level of supersaturation above which spontaneous nucleation occurs instantly. ...
January 2018
... Typical emission spectra resulted from 3 scans of 0.2 s dwell time each, utilising moderate excitation (Δλ = 1 − 4 nm) and fine emission (Δλ < 0.5 nm) bandwidths, optimising peak signal to ∼700,00 counts per second (cps) with sample optical density of less than 0.1 au at the excitation wavelength. Quantum yields for these QDs have been previously measured [14,19,20]. ...
April 2018
Nanoscale
... Elmas et al. synthesized a platinum-group metal-selective electropolymerizable monomer (4-(terthiophenyl)-terpyridin) with a pendant terpyridine unit by utilizing a metal-selective ligand approach. The metallopolymer had highly active Pt SAs that catalyzed the HER [60]. ...
September 2017
ACS Sustainable Chemistry & Engineering
... In particular, high-quality solution phase synthesis routes have been used to produce low-dispersion colloidal suspensions containing nanocubes of the fully inorganic cesium lead bromide perovskite CsPbBr 3 with edge lengths ranging from 2 to 5 nm. 17,18 To the best of our knowledge, in this specific size range composed of ultrasmall cube-shaped CsPbBr 3 QDs (average edge length smaller than 5 nm), the influence of finite confinement potential on the energy spectra of the confined charge carriers has not yet been addressed. In fact, in the most prominent studies on nanosized perovskites, [17][18][19][20][21][22] the lowest excited state energy of the electron-hole pair is calculated assuming a priori an infinitely high confinement potential regardless of the considered particle size and its characteristic quantum regime. ...
March 2017
Chemistry of Materials
... The dense sp 2hybridized carbon atoms with zero-dimensional honeycomb lattices of GOQDs contribute to the exceptional optical properties, making them a promising fluorescent probe for in vivo imaging. 18 The synthesis of GOQDs mainly includes the chemical exfoliation of graphite nanoparticles, 19 electrochemical treatment of citric acid, 20 ammonia-treated oxidation of graphene oxide, 21 microwave heating of carbon nanotubes, mixed strong acid oxidation-assisted ultrasonication of graphite nanoparticles, 22 pulse lazar ablation of coal in ethanol, 23 and so forth. Most reported methods are complicated and timeconsuming, involving strong chemicals and demanding easy alternative methods. ...
March 2017
Microchimica Acta
... Chen et al. 44 assembled Au and TiO 2 NPs with the help of a Langmuir Blodgett trough to create Janus particles. Other approaches used for heterodimer assembly include the use of nanoscopic phase separation of different metals to form dimers, 45 the use of coordination chemistry to link nanoparticles through various molecules, 46-48 the use of solid supports during synthesis, 49 and the use of electron beam lithography 50 but many of these methods are designed for specific combinations of NPs or require significant experimental steps or costs. 51 There is not yet a general approach to the formation of heterodimers, like the methods mentioned above for the formation of homodimers, especially for dimers with the small gaps necessary for broader application purposes. ...
October 2015
Microchimica Acta
... [16] Alternatively, ligand exchange can be conducted in an indirect manner by introducing additional step(s) to facilitate the use of a ligand weaker in binding strength or with an opposite charge. [22] In one study, the original ligand was removed using acid treatment under sonication, followed by the deposition of the ligand of interest and then thermal treatment. [19] This approach tended to trigger aggregation if the pH of the solution is not optimized. ...
August 2014