Solvent-Ligand Interactions in Colloidal Nanocrystals

2018 ◽  
Author(s):  
Jonathan De Roo ◽  
Nuri Yazdani ◽  
Emile Drijvers ◽  
Alessandro Lauria ◽  
Jorick Maes ◽  
...  
Keyword(s):  
Direct Method ◽  
Line Broadening ◽  
H Nmr ◽  
Size Dependent ◽  
Line Shape Analysis ◽  
Wide Range ◽  
Nanocrystal Synthesis ◽  
Ligand Interactions ◽  
Indispensable Tool ◽  
Theoretical Evidence

<p>Although solvent-ligand interactions play a major role in nanocrystal synthesis, dispersion formulation and assembly, there is currently no direct method to study this. Here we examine the broadening of <sup>1</sup>H NMR resonances associated with bound ligands, and turn this poorly understood descriptor into a tool to assess solvent-ligand interactions. We show that the line broadening has both a homogeneous and a heterogeneous component. The former is nanocrystal-size dependent and the latter results from solvent-ligand interactions. Our model is supported by experimental and theoretical evidence that correlates broad NMR lines with poor ligand solvation. This correlation is found across a wide range of solvents, extending from water to hexane, for both hydrophobic and hydrophilic ligand types, and for a multitude of oxide, sulfide and selenide nanocrystals. Our findings thus put forward NMR line shape analysis as an indispensable tool to form, investigate and manipulate nanocolloids.</p>

Solvent-Ligand Interactions in Colloidal Nanocrystals

2018 ◽  
Author(s):  
Jonathan De Roo ◽  
Nuri Yazdani ◽  
Emile Drijvers ◽  
Alessandro Lauria ◽  
Jorick Maes ◽  
...  
Keyword(s):  
Direct Method ◽  
Line Broadening ◽  
H Nmr ◽  
Size Dependent ◽  
Line Shape Analysis ◽  
Wide Range ◽  
Nanocrystal Synthesis ◽  
Ligand Interactions ◽  
Indispensable Tool ◽  
Theoretical Evidence

<p>Although solvent-ligand interactions play a major role in nanocrystal synthesis, dispersion formulation and assembly, there is currently no direct method to study this. Here we examine the broadening of <sup>1</sup>H NMR resonances associated with bound ligands, and turn this poorly understood descriptor into a tool to assess solvent-ligand interactions. We show that the line broadening has both a homogeneous and a heterogeneous component. The former is nanocrystal-size dependent and the latter results from solvent-ligand interactions. Our model is supported by experimental and theoretical evidence that correlates broad NMR lines with poor ligand solvation. This correlation is found across a wide range of solvents, extending from water to hexane, for both hydrophobic and hydrophilic ligand types, and for a multitude of oxide, sulfide and selenide nanocrystals. Our findings thus put forward NMR line shape analysis as an indispensable tool to form, investigate and manipulate nanocolloids.</p>

Determination of the Accurate Values of the Rate Constant and Thermodynamic Parameters for the Rotation About the C(sp2)-C(aryl) Bond; Adamantan-1-yl 3-Bromo-2,4,6-trimethylphenyl Ketone

1998 ◽  
Vol 63 (7) ◽  
pp. 955-966
Author(s):  
Eva Přibylová ◽  
Miroslav Holík
Keyword(s):  
Thermodynamic Parameters ◽  
Shape Analysis ◽  
Rate Constants ◽  
Line Shape ◽  
Microsoft Excel ◽  
Hindered Rotation ◽  
H Nmr ◽  
Line Shape Analysis ◽  
Coalescence Temperature

Four programs for the 1H NMR line shape analysis: two commercial - Winkubo (Bruker) and DNMR5 (QCPE 165) and two written in our laboratory - Newton (in Microsoft Excel) and Simtex (in Matlab) have been tested in order to get highly accurate rate constants of the hindered rotation about a single bond. For this purpose four testing criteria were used, two of them were also developed by us. As supplementary determinations the rate constants obtained for the coalescence temperature and for the thermal racemization of chromatographically separated enantiomers were used which fitted well the temperature dependence of the rate constants determined by the line shape analysis. As a test compound adamantan-1-yl 3-bromo-2,4,6-trimethylphenyl ketone was prepared and studied. It was shown that supermodified simplex method used in our algorithm (Simtex), though time consuming, gives the most accurate values of the rate constants and consequently the calculated thermodynamic parameters Ea, ∆H≠, and ∆S≠ lay in relatively narrow confidence intervals.

Monitoring the encapsulation of chlorin e6 derivatives into polymer carriers by NMR spectroscopy

2019 ◽  
Vol 23 (11n12) ◽  
pp. 1576-1586 ◽  
Author(s):  
Sara Pfister ◽  
Luca Sauser ◽  
Ilche Gjuroski ◽  
Julien Furrer ◽  
Martina Vermathen
Keyword(s):  
Relaxation Time ◽  
Nmr Spectroscopy ◽  
Core Region ◽  
Chlorin E6 ◽  
Polypropylene Glycol ◽  
Polymer Carriers ◽  
H Nmr ◽  
Line Shape Analysis ◽  
Dynamic Methods ◽  
Derivatives Of

The encapsulation of five derivatives of chlorin e6 with different hydrophobicity and aggregation properties into a series of five poloxamer-type triblock copolymer micelles (BCMs) with varying numbers of polyethylene and polypropylene glycol (PEG, PPG) units was monitored using 1H NMR spectroscopy. NMR chemical shift and line shape analysis, as well as dynamic methods including diffusion ordered spectroscopy (DOSY) and T1 and T2 relaxation time measurements of the chlorin and the polymer resonances, proved useful to assess the chlorin–BCM compatibility. The poloxamers had high capability to break up aggregates formed by chlorins up to intermediate hydrophobicity. Physically entrapped chlorins were always localized in the BCM core region. The loading capacity correlated with chlorin polarity for all poloxamers among which those with the lowest number of PPG units were most efficient. DOSY data revealed that relatively weakly aggregating chlorins partition between the aqueous bulk and micellar environment whereas more hydrophobic chlorins are well retained in the BCM core region, rendering these systems more stable. T1 and T2 relaxation time measurements indicated that motional freedom in the BCM core region contributes to encapsulation efficiency. The BCM corona dynamics were rather insensitive towards chlorin entrapment except for the poloxamers with short PEG chains. The presented data demonstrate that 1H NMR spectroscopy is a powerful complementary tool for probing the compatibility of porphyrinic compounds with polymeric carriers such as poloxamer BCMs, which is a prerequisite in the development of stable and highly efficient drug delivery systems suitable for medical applications like photodynamic therapy of tumors.

Synthesis and characterization of a new series of thiadiazole derivatives as potential anticancer agents

2020 ◽  
Vol 26 (1) ◽  
pp. 6-13 ◽  
Author(s):  
Ulviye Acar Çevik ◽  
Derya Osmaniye ◽  
Serkan Levent ◽  
Begüm Nurpelin Sağlik ◽  
Betül Kaya Çavuşoğlu ◽  
...  
Keyword(s):  
Anticancer Agents ◽  
Biological Activities ◽  
Cancer Cell Line ◽  
Chemotherapeutic Agents ◽  
Anticancer Activities ◽  
Normal Tissues ◽  
H Nmr ◽  
Wide Range ◽  
Thiadiazole Derivatives ◽  
Low Efficiency

AbstractCancer is one of the most common causes of death in the world. Despite the importance of combating cancer in healthcare systems and research centers, toxicity in normal tissues and the low efficiency of anticancer drugs are major problems in chemotherapy. Nowadays the aim of many medical research projects is to discover new safer and more effective anticancer agents. 1,3,4-Thiadiazole compounds are important fragments in medicinal chemistry because of their wide range of biological activities, including anticancer activities. The aim of this study was to determine the capacity of newly synthesized 1,3,4-thiadiazole compounds as chemotherapeutic agents. The structures of the obtained compounds were elucidated using 1H-NMR, 13C-NMR and mass spectrometry. Although the thiadiazole derivatives did not prove to be significantly cytotoxic to the tumour tissue cultures, compound 4i showed activity against the C6 rat brain cancer cell line (IC50 0.097 mM) at the tested concentrations.

scholarly journals Size matters: Size Dependency of Gold Nanoparticles Interacting with Model Membranes

2019 ◽  
Author(s):  
Claudia Contini ◽  
James W. Hindley ◽  
Tom Macdonald ◽  
Joseph Barritt ◽  
Oscar Ces ◽  
...  
Keyword(s):  
Gold Nanoparticles ◽  
Lipid Bilayers ◽  
Lipid Membrane ◽  
Rapid Development ◽  
Membrane System ◽  
Size Dependent ◽  
Research Fields ◽  
Large Unilamellar Vesicles ◽  
Wide Range ◽  
Experimental Characterisation

<p><b>The rapid development of nanomaterials has led to an increase in the number and variety of engineered nanomaterials (ENMs) in the environment. Gold nanoparticles (AuNPs) are an example of a commonly studied ENM whose highly tailorable properties have generated significant interest through a wide range of research fields. In the present work, we report the first qualitative as well as quantitative experimental characterisation of the AuNP-membrane interaction. We investigate the interactions between citrate-stabilised AuNPs (diameters 5, 10, 25, 35, 50, 60 nm) and large unilamellar vesicles (LUVs) acting as a model membrane system. LUVs were prepared in two different formulations using 1-palmitoyl-2-oleoyl-glycero-3-phosphocholine (POPC) and 1,2-dileoyl-sn-glycero-3-phosphocholine (DOPC). Our results show that the interaction between AuNPs and LUVs is size dependent; in particular, we reveal the existence of two AuNP’s critical diameters which determine the fate of AuNPs in contact with a lipid membrane. The results provide a new understanding of the size dependent interaction between AuNPs and lipid bilayers of direct relevance to nanotoxicology and to the design of NP vectors.</b></p>

Functionalization of Gold Nanoparticles with Monosaccharide Mannose

2021 ◽  
pp. 6281-6284
Author(s):  
Sambit Dash ◽  
Pragna Rao ◽  
Ullas Kamath ◽  
Aparna R Pai ◽  
Prasanna Kumar Reddy Gayam ◽  
...  
Keyword(s):  
Gold Nanoparticles ◽  
Phase Transfer ◽  
Colour Change ◽  
Cost Effective ◽  
Biomedical Sciences ◽  
Size Dependent ◽  
Nanoparticles Dispersion ◽  
Wide Range ◽  
Three Stages ◽  
Transfer Method

Gold nanoparticles have found a wide range of application in biomedical sciences. Unique properties of these metal nanoparticles include surface plasmon resonance and size dependent colour change. Various molecules have been functionalized on the gold nanoparticles surface but carbohydrates have garnered attention due to their properties and their role in living systems. However certain challenges make carbohydrate-gold nanoparticles association difficult to obtain and stabilize. This study was carried out to chemically remodel gold nanoparticles by adding a monosaccharide mannose to its surface. A modified phase transfer method was used to synthesize gold nanoparticles. The surface of the nanoparticles was fixed with cyanuric chloride to serve as a linker. Mannose was then linked to the linker molecule. All three stages of the process, gold nanoparticles, and gold nanoparticles with linker and gold nanoparticles with the carbohydrate were analyzed for size and stability. Zeta potential and UV-vis data exhibited stable gold nanoparticles dispersion, successful binding of linker molecule as well as the carbohydrate. This study shows a simple, cost-effective and robust method of glycomodification of gold nanoparticles surface which can further find use in wide ranging applications.

Information Systems Outsourcing in Large Companies

2012 ◽  
pp. 1554-1568
Author(s):  
Mark Leeney ◽  
João Varajão ◽  
António Trigo Ribeiro ◽  
Ricardo Colomo-Palacios
Keyword(s):  
Project Management ◽  
Information Systems ◽  
Software Development ◽  
Focus Attention ◽  
Communications Networks ◽  
Republic Of Ireland ◽  
The Past ◽  
Wide Range ◽  
The Republic ◽  
Indispensable Tool

Information systems outsourcing is an indispensable tool in the management of information systems. The set of services contracted to outside suppliers, originally more limited to services of an operational nature, has expanded over the past two decades, and today there is a wide range of services subject to outsourcing. Among them are: the hiring of software development; maintenance of applications; services and communications networks; security of information systems; and many others. Depending on the nature of the services contracted and on the range that the contracting of services has on departments of information systems, the issues involved in project management vary considerably. This article presents the results of a survey conducted among large companies in the Republic of Ireland to characterize, among other things, the range of services that are most often outsourced. The results are relevant in the sense that not only do they enable a better understanding of the reality of information systems departments of large Irish companies, but also enable the management to focus attention on specific services.

scholarly journals Three routine methods for measuring high-density lipoprotein cholesterol compared with the Reference Method

1996 ◽  
Vol 42 (5) ◽  
pp. 738-743 ◽  
Author(s):  
N Harris ◽  
V Galpchian ◽  
N Rifai
Keyword(s):  
High Density Lipoprotein ◽  
High Density Lipoprotein Cholesterol ◽  
Dextran Sulfate ◽  
Direct Method ◽  
Density Lipoprotein ◽  
Reference Method ◽  
High Density ◽  
Lipoprotein Cholesterol ◽  
Direct Assay ◽  
Wide Range

Abstract We compared the performance of three methods for quantifying high-density lipoprotein cholesterol (HDL-C) with the Reference Method for HDL-C, using samples with a wide range of triglyceride (TG) concentrations (290-18000 mg/L). All three comparison assays-- utilizing a magnetic dextran sulfate precipitating reagent, a direct method, and a standard MgCl2-dextran sulfate reagent--were precise, with a run-to-run CV of less than or equal to 4.1%. However, the systematic error of these assays exceeded the National Cholesterol Education Program (NCEP) performance goal of less than or equal to 10% in half of the concentration ranges tested. Nevertheless, the total error of the assays generally meets the current 22% limit set by the NCEP. Although both the magnetic dextran sulfate precipitation reagent and the direct assay can be performed more rapidly than the MgCl2-dextran sulfate assay, the direct assay involves no sample preparation and requires only 4 microL of sample excluding the dead space. Although precipitation is frequently inadequate with the MgCl2-dextran sulfate reagent at TG concentrations &gt;6000 mg/L, both the magnetic and the direct reagent show no interference from high TG concentrations as great as 18 000 mg/L.

scholarly journals Extracellular Vesicles as Nanotherapeutics for Parkinson’s Disease

Biomolecules ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 1327 ◽  
Author(s):  
Loredana Leggio ◽  
Greta Paternò ◽  
Silvia Vivarelli ◽  
Francesca L’Episcopo ◽  
Cataldo Tirolo ◽  
...  
Keyword(s):  
Extracellular Vesicles ◽  
Cell Communication ◽  
Bioactive Molecules ◽  
Substantia Nigra Pars Compacta ◽  
Diagnostic Tools ◽  
Target Cells ◽  
Small Interfering Rnas ◽  
Wide Range ◽  
Ligand Interactions ◽  
The Central Nervous System

Extracellular vesicles (EVs) are naturally occurring membranous structures secreted by normal and diseased cells, and carrying a wide range of bioactive molecules. In the central nervous system (CNS), EVs are important in both homeostasis and pathology. Through receptor–ligand interactions, direct fusion, or endocytosis, EVs interact with their target cells. Accumulating evidence indicates that EVs play crucial roles in the pathogenesis of many neurodegenerative disorders (NDs), including Parkinson′s disease (PD). PD is the second most common ND, characterized by the progressive loss of dopaminergic (DAergic) neurons within the Substantia Nigra pars compacta (SNpc). In PD, EVs are secreted by both neurons and glial cells, with either beneficial or detrimental effects, via a complex program of cell-to-cell communication. The functions of EVs in PD range from their etiopathogenetic relevance to their use as diagnostic tools and innovative carriers of therapeutics. Because they can cross the blood–brain barrier, EVs can be engineered to deliver bioactive molecules (e.g., small interfering RNAs, catalase) within the CNS. This review summarizes the latest findings regarding the role played by EVs in PD etiology, diagnosis, prognosis, and therapy, with a particular focus on their use as novel PD nanotherapeutics.

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