scholarly journals Fluorescent Nanodiamond–Nanogels for Nanoscale Sensing and Photodynamic Applications

2020 ◽  
Author(s):  
Yingke Wu ◽  
Md Noor A Alam ◽  
Priyadharshini Balasubramanian ◽  
Pia Winterwerber ◽  
Anna Ermakova ◽  
...  
Keyword(s):  
Electrostatic Interactions ◽  
Colloidal Stability ◽  
Monomer Concentration ◽  
Biological Applications ◽  
Chemical Surface ◽  
Reactive Groups ◽  
Fluorescent Nanodiamonds ◽  
Nanoscale Sensing ◽  
Post Modification ◽  
The Impact

Fluorescent nanodiamonds (NDs) are carbon-based nanoparticles with various outstanding magneto-optical properties. After preparation, NDs have a variety of different surface groups that determine their physicochemical properties. For biological applications, surface modifications are crucial to impart a new interphase for controlled interactions with biomolecules or cells. Herein, a straight-forward synthesis concept denoted "adsorption-crosslinking" is applied for the efficient modification of NDs, which sequentially combines fast non-covalent adsorption based on electrostatic interactions and subsequent covalent cross-linking. As a result, a very thin and uniform nanogel coating surrounding the NDs is obtained, which imparts reactive groups as well as high colloidal stability. The impact of the reaction time, monomer concentration, molecular weight, and structure of the cross-linker on the resulting nanogel shell, the availability of reactive chemical surface functions and the quantum sensing properties of the coated NDs has been assessed and optimized. Post-modification of the nanogel-coated NDs was achieved with phototoxic ruthenium complexes yielding ND-based probes suitable for photodynamic applications. The adsorption-crosslinking ND functionalization reported herein provides new avenues towards functional probes and traceable nanocarriers for high resolution bioimaging, nanoscale sensing and photodynamic applications. <br>

scholarly journals Fluorescent Nanodiamond–Nanogels for Nanoscale Sensing and Photodynamic Applications

2020 ◽  
Author(s):  
Yinke Wu ◽  
Md Noor A Alam ◽  
Priyadharshini Balasubramanian ◽  
Pia Winterwerber ◽  
Anna Ermakova ◽  
...  
Keyword(s):  
Electrostatic Interactions ◽  
Colloidal Stability ◽  
Monomer Concentration ◽  
Biological Applications ◽  
Chemical Surface ◽  
Reactive Groups ◽  
Fluorescent Nanodiamonds ◽  
Nanoscale Sensing ◽  
Post Modification ◽  
The Impact

Fluorescent nanodiamonds (NDs) are carbon-based nanoparticles with various outstanding magneto-optical properties. After preparation, NDs have a variety of different surface groups that determine their physicochemical properties. For biological applications, surface modifications are crucial to impart a new interphase for controlled interactions with biomolecules or cells. Herein, a straight-forward synthesis concept denoted "adsorption-crosslinking" is applied for the efficient modification of NDs, which sequentially combines fast non-covalent adsorption based on electrostatic interactions and subsequent covalent cross-linking. As a result, a very thin and uniform nanogel coating surrounding the NDs is obtained, which imparts reactive groups as well as high colloidal stability. The impact of the reaction time, monomer concentration, molecular weight, and structure of the cross-linker on the resulting nanogel shell, the availability of reactive chemical surface functions and the quantum sensing properties of the coated NDs has been assessed and optimized. Post-modification of the nanogel-coated NDs was achieved with phototoxic ruthenium complexes yielding ND-based probes suitable for photodynamic applications. The adsorption-crosslinking ND functionalization reported herein provides new avenues towards functional probes and traceable nanocarriers for high resolution bioimaging, nanoscale sensing and photodynamic applications. <br>

Fluorescent Nanodiamond–Nanogels for Nanoscale Sensing and Photodynamic Applications

2020 ◽  
Author(s):  
Yingke Wu ◽  
Md Noor A Alam ◽  
Priyadharshini Balasubramanian ◽  
Pia Winterwerber ◽  
Anna Ermakova ◽  
...  
Keyword(s):  
Electrostatic Interactions ◽  
Colloidal Stability ◽  
Monomer Concentration ◽  
Biological Applications ◽  
Chemical Surface ◽  
Reactive Groups ◽  
Fluorescent Nanodiamonds ◽  
Nanoscale Sensing ◽  
Post Modification ◽  
The Impact

Fluorescent nanodiamonds (NDs) are carbon-based nanoparticles with various outstanding magneto-optical properties. After preparation, NDs have a variety of different surface groups that determine their physicochemical properties. For biological applications, surface modifications are crucial to impart a new interphase for controlled interactions with biomolecules or cells. Herein, a straight-forward synthesis concept denoted "adsorption-crosslinking" is applied for the efficient modification of NDs, which sequentially combines fast non-covalent adsorption based on electrostatic interactions and subsequent covalent cross-linking. As a result, a very thin and uniform nanogel coating surrounding the NDs is obtained, which imparts reactive groups as well as high colloidal stability. The impact of the reaction time, monomer concentration, molecular weight, and structure of the cross-linker on the resulting nanogel shell, the availability of reactive chemical surface functions and the quantum sensing properties of the coated NDs has been assessed and optimized. Post-modification of the nanogel-coated NDs was achieved with phototoxic ruthenium complexes yielding ND-based probes suitable for photodynamic applications. The adsorption-crosslinking ND functionalization reported herein provides new avenues towards functional probes and traceable nanocarriers for high resolution bioimaging, nanoscale sensing and photodynamic applications. <br>

scholarly journals A Microwave-Assisted Synthesis of Zinc Oxide Nanocrystals Finely Tuned for Biological Applications

Nanomaterials ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 212 ◽  
Author(s):  
Nadia Garino ◽  
Tania Limongi ◽  
Bianca Dumontel ◽  
Marta Canta ◽  
Luisa Racca ◽  
...  
Keyword(s):  
Zinc Oxide ◽  
Colloidal Stability ◽  
Cell Uptake ◽  
Biological Behavior ◽  
Microwave Assisted Synthesis ◽  
Biological Applications ◽  
Uniform Size ◽  
Chemical Surface ◽  
Microwave Assisted ◽  
Synthesis Procedure

Herein we report a novel, easy, fast and reliable microwave-assisted synthesis procedure for the preparation of colloidal zinc oxide nanocrystals (ZnO NCs) optimized for biological applications. ZnO NCs are also prepared by a conventional solvo-thermal approach and the properties of the two families of NCs are compared and discussed. All of the NCs are fully characterized in terms of morphological analysis, crystalline structure, chemical composition and optical properties, both as pristine nanomaterials or after amino-propyl group functionalization. Compared to the conventional approach, the novel microwave-derived ZnO NCs demonstrate outstanding colloidal stability in ethanol and water with long shelf-life. Furthermore, together with their more uniform size, shape and chemical surface properties, this long-term colloidal stability also contributes to the highly reproducible data in terms of biocompatibility. Actually, a significantly different biological behavior of the microwave-synthesized ZnO NCs is reported with respect to NCs prepared by the conventional synthesis procedure. In particular, consistent cytotoxicity and highly reproducible cell uptake toward KB cancer cells are measured with the use of microwave-synthesized ZnO NCs, in contrast to the non-reproducible and scattered data obtained with the conventionally-synthesized ones. Thus, we demonstrate how the synthetic route and, as a consequence, the control over all the nanomaterial properties are prominent points to be considered when dealing with the biological world for the achievement of reproducible and reliable results, and how the use of commercially-available and under-characterized nanomaterials should be discouraged in this view.

The Impact of Bioconjugation on the Interfacial Activity of a Protein Biosurfactant

2018 ◽  
Author(s):  
Hossam H Tayeb ◽  
Marina Stienecker ◽  
Anton Middelberg ◽  
Frank Sainsbury
Keyword(s):  
Polyethylene Glycol ◽  
Colloidal Stability ◽  
Point Mutations ◽  
Pharmaceutical Formulations ◽  
Industrial Processes ◽  
Parent Molecule ◽  
Site Specific ◽  
Interfacial Activity ◽  
Surface Active ◽  
The Impact

Biosurfactants, are surface active molecules that can be produced by renewable, industrially scalable biologic processes. DAMP4, a designer biosurfactant, enables the modification of interfaces via genetic or chemical fusion to functional moieties. However, bioconjugation of addressable amines introduces heterogeneity that limits the precision of functionalization as well as the resolution of interfacial characterization. Here we designed DAMP4 variants with cysteine point mutations to allow for site-specific bioconjugation. The DAMP4 variants were shown to retain the structural stability and interfacial activity characteristic of the parent molecule, while permitting efficient and specific conjugation of polyethylene glycol (PEG). PEGylation results in a considerable reduction on the interfacial activity of both single and double mutants. Comparison of conjugates with one or two conjugation sites shows that both the number of conjugates as well as the mass of conjugated material impacts the interfacial activity of DAMP4. As a result, the ability of DAMP4 variants with multiple PEG conjugates to impart colloidal stability on peptide-stabilized emulsions is reduced. We suggest that this is due to constraints on the structure of amphiphilic helices at the interface. Specific and efficient bioconjugation permits the exploration and investigation of the interfacial properties of designer protein biosurfactants with molecular precision. Our findings should therefore inform the design and modification of biosurfactants for their increasing use in industrial processes, and nutritional and pharmaceutical formulations.

scholarly journals Cooperation/Competition between Halogen Bonds and Hydrogen Bonds in Complexes of 2,6-Diaminopyridines and X-CY3 (X = Cl, Br; Y = H, F)

Symmetry ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 766
Author(s):  
Barbara Bankiewicz ◽  
Marcin Palusiak
Keyword(s):  
Complex Formation ◽  
Hydrogen Bonds ◽  
Dft Calculations ◽  
Electrostatic Interactions ◽  
Dipole Moments ◽  
Main Role ◽  
Halogen Bonds ◽  
Topological Parameters ◽  
Leading Role ◽  
The Impact

The DFT calculations have been performed on a series of two-element complexes formed by substituted 2,6-diaminopyridine (R−PDA) and pyridine (R−Pyr) with X−CY3 molecules (where X = Cl, Br and Y = H, F). The primary aim of this study was to examine the intermolecular hydrogen and halogen bonds in the condition of their mutual coexistence. Symmetry/antisymmetry of the interrelation between three individual interactions is addressed. It appears that halogen bonds play the main role in the stabilization of the structures of the selected systems. However, the occurrence of one or two hydrogen bonds was associated with the favourable geometry of the complexes. Moreover, the impact of different substituent groups attached in the para position to the aromatic ring of the 2,6-diaminopyridine and pyridine on the character of the intermolecular hydrogen and halogen bonds was examined. The results indicate that the presence of electron-donating substituents strengthens the bonds. In turn, the presence of electron-withdrawing substituents reduces the strength of halogen bonds. Additionally, when hydrogen and halogen bonds lose their leading role in the complex formation, the nonspecific electrostatic interactions between dipole moments take their place. Analysis was based on geometric, energetic, and topological parameters of the studied systems.

scholarly journals ATP and Tri-Polyphosphate (TPP) Suppress Protein Aggregate Growth by a Supercharging Mechanism

Biomedicines ◽  
2021 ◽  
Vol 9 (11) ◽  
pp. 1646
Author(s):  
Jordan Bye ◽  
Kiah Murray ◽  
Robin Curtis
Keyword(s):  
Protein Interactions ◽  
Electrostatic Interactions ◽  
Colloidal Stability ◽  
Conformational Stability ◽  
Kinetic Studies ◽  
Structural Factors ◽  
Protein Protein Interactions ◽  
Protein Aggregate ◽  
Aggregate Growth

A common strategy to increase aggregation resistance is through rational mutagenesis to supercharge proteins, which leads to high colloidal stability, but often has the undesirable effect of lowering conformational stability. We show this trade-off can be overcome by using small multivalent polyphosphate ions, adenosine triphosphate (ATP) and tripolyphosphate (TPP) as excipients. These ions are equally effective at suppressing aggregation of ovalbumin and bovine serum albumin (BSA) upon thermal stress as monitored by dynamic and static light scattering. Monomer loss kinetic studies, combined with measurements of native state protein–protein interactions and ζ-potentials, indicate the ions reduce aggregate growth by increasing the protein colloidal stability through binding and overcharging the protein. Out of three additional proteins studied, ribonuclease A (RNaseA), α-chymotrypsinogen (α-Cgn), and lysozyme, we only observed a reduction in aggregate growth for RNaseA, although overcharging by the poly-phosphate ions still occurs for lysozyme and α-Cgn. Because the salts do not alter protein conformational stability, using them as excipients could be a promising strategy for stabilizing biopharmaceuticals once the protein structural factors that determine whether multivalent ion binding will increase colloidal stability are better elucidated. Our findings also have biological implications. Recently, it has been proposed that ATP also plays an important role in maintaining intracellular biological condensates and preventing protein aggregation in densely packed cellular environments. We expect electrostatic interactions are a significant factor in determining the stabilizing ability of ATP towards maintaining proteins in non-dispersed states in vivo.

scholarly journals Wetting transition of ionic liquids at metal surfaces: A computational molecular approach to electronic screening using a virtual Thomas-Fermi fluid

2020 ◽  
Author(s):  
Alexander Schlaich ◽  
Dongliang Jin ◽  
Lyderic Bocquet ◽  
Benoit Coasne
Keyword(s):  
Ionic Liquids ◽  
Energy Storage ◽  
Electrostatic Interactions ◽  
Debye Length ◽  
Wetting Transition ◽  
Molecular Fluids ◽  
Thomas Fermi ◽  
Electronic Screening ◽  
Novel Approach ◽  
The Impact

Abstract Of particular relevance to energy storage, electrochemistry and catalysis, ionic and dipolar liquids display a wealth of unexpected fundamental behaviors – in particular in confinement. Beyond now well-documented adsorption, overscreening and crowding effects1,2,3, recent experiments have highlighted novel phenomena such as unconventional screening4 and the impact of the electronic nature – metallic versus insulating – of the confining surface on wetting/phase transitions5,6. Such behaviors, which challenge existing theoretical and numerical modeling frameworks, point to the need for new powerful tools to embrace the properties of confined ionic/dipolar liquids. Here, we introduce a novel atom-scale approach which allows for a versatile description of electronic screening while capturing all molecular aspects inherent to molecular fluids in nanoconfined/interfacial environments. While state of the art molecular simulation strategies only consider perfect metal or insulator surfaces, we build on the Thomas-Fermi formalism for electronic screening to develop an effective approach that allows dealing with any imperfect metal between these asymptotes. The core of our approach is to describe electrostatic interactions within the metal through the behavior of a `virtual' Thomas-Fermi fluid of charged particles, whose Debye length sets the Thomas-Fermi screening length λ in the metal. This easy-to-implement molecular method captures the electrostatic interaction decay upon varying λ from insulator to perfect metal conditions, while describing very accurately the capacitance behavior – and hence the electrochemical properties – of the metallic confining medium. By applying this strategy to a nanoconfined ionic liquid, we demonstrate an unprecedented wetting transition upon switching the confining medium from insulating to metallic. This novel approach provides a powerful framework to predict the unsual behavior of ionic liquids, in particular inside nanoporous metallic structures, with direct applications for energy storage and electrochemistry.

Impact of Molecular Chain Structure of Suspension Phase on Giant Electrorheological Performance

2022 ◽  
Author(s):  
Hanqi Xu ◽  
Jinbo Wu ◽  
Yaying Hong ◽  
Weijia Wen
Keyword(s):  
Yield Stress ◽  
Chain Length ◽  
Colloidal Stability ◽  
Chain Structure ◽  
Solid Particles ◽  
High Yield ◽  
Suspension Stability ◽  
Chain Lengths ◽  
The Impact ◽  
Oil Particles

Abstract We demonstrate the impact of diester structure, in particular the alkyl chain length and branching structure, on the giant electrorheological (GER) effect and suspension stability. The existence of oil-particles interaction is of critical importance to induce the GER effect. To quantify GER performance and colloidal stability, we examine the yield stress, current density, field-off viscosity and sedimentation ratio with respect to the variation of chain length and branching structure. The oil-particles interaction is quantitatively analyzed by investigating the cluster size of particles in different diesters by a multiple light scattering analyzer, along with the wettability of different chain lengths of diesters and solid particles by the Washburn method. Our results indicate that long chain lengths favor the formation of particle agglomerates, thereby enhancing the GER effect (such as high yield stress). The attachment of branches on diester causes the formation of electronic correlation between branches and main chain, depending on the position of branches located, and hence results in superior GER performance and favorable suspension stability. An optimal GER fluid constituted by bis(2-ethylhexyl) sebacate is acquired with the achieved yield stress of 113 kPa at electric field strength of 4 kV/ mm and the prominent integrated GER properties.

Surfactant Effect on the Electrorheological Performance and Colloidal Stability

Soft Matter ◽  
2021 ◽  
Author(s):  
Hanqi Xu ◽  
Jinbo Wu ◽  
Yaying Hong ◽  
Weijia Wen
Keyword(s):  
Nonionic Surfactants ◽  
Colloidal Stability ◽  
Silicone Oil ◽  
Surfactant Effect ◽  
Barium Titanyl Oxalate ◽  
The Impact ◽  
Titanyl Oxalate

The impact of two nonionic surfactants, namely Span 20 and Span 85, on the electrorheological response and colloidal stability of urea-coated barium titanyl oxalate (BTRU)/silicone oil suspensions is investigated. We...

A model study on the impact of metal ions on pre-vulcanization of concentrated natural rubber latex and dipped-products

2021 ◽  
pp. 147776062110629
Author(s):  
Porntip Rojruthai ◽  
Narueporn Payungwong ◽  
Jitladda T Sakdapipanich
Keyword(s):  
Natural Rubber ◽  
Metal Ions ◽  
Colloidal Stability ◽  
Mechanical Stability ◽  
Testing Machine ◽  
Natural Rubber Latex ◽  
Tensile Testing Machine ◽  
Model Study ◽  
Stability Time ◽  
The Impact

A model study on the influence of some heavy metal ions on the stability and vulcanization efficiency of uncompounded and compounded high-ammonia natural rubber (HANR) latex was carried out by an exogenous addition and then determined by Brookfield viscometer, mechanical stability time (MST) tester, and tensile testing machine. The case of pre-vulcanized HANR latex with different aging times was determined by the change in the volatile fatty acid (VFA) number, MST, and viscosity. The compounded HANR latex was coagulated by adding Mn2+and Mg2+ while it was unaltered by adding Zn2+, Fe2+, and Cu2+ ions, leading to their colloidal stability. Therefore, these metal ions were chosen further to study the pre-vulcanization of compounded HANR latex. The presence of Zn2+, Fe2+, and Cu2+ in the latex is responsible for the delay in the vulcanization process and changes the appearance of compounded latex. Before compounding, the addition of such metal ions led to the reduction in tensile strength of the obtained gloves. At the same time, there was no effect on the tensile properties of the gloves made from the compounded HANR latex containing the metal ions.

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