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Hanigan-Diebel J, Costin RJ, Myers LC, Vandermeer CI, Willis MS, Takhar K, Odinakachukwu OV, Carroll MG, Schiffbauer JE, Lohse SE. Affinity Constants of Bovine Serum Albumin for 5 nm Gold Nanoparticles (AuNPs) with ω-Functionalized Thiol Monolayers Determined by Fluorescence Spectroscopy. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2024; 40. [PMID: 39013805 PMCID: PMC11295198 DOI: 10.1021/acs.langmuir.4c01234] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/02/2024] [Revised: 07/09/2024] [Accepted: 07/10/2024] [Indexed: 07/18/2024]
Abstract
A detailed understanding of the binding of serum proteins to small (dcore <10 nm) nanoparticles (NPs) is essential for the mediation of protein corona formation in next generation nanotherapeutics. While a number of studies have investigated the details of protein adsorption on large functionalized NPs, small NPs (with a particle surface area comparable in size to the protein) have not received extensive study. This study determined the affinity constant (Ka) of BSA when binding to three different functionalized 5 nm gold nanoparticles (AuNPs). AuNPs were synthesized using three ω-functionalized thiols (mercaptoethoxy-ethoxy-ethanol (MEEE), mercaptohexanoic acid (MHA), and mercaptopentyltrimethylammonium chloride (MPTMA)), giving rise to particles with three different surface charges. The binding affinity of bovine serum albumin (BSA) to the different AuNP surfaces was investigated using UV-visible absorbance spectroscopy, dynamic light scattering (DLS), and fluorescence quenching titrations. Fluorescence titrations indicated that the affinity of BSA was actually highest for small AuNPs with a negative surface charge (MHA-AuNPs). Interestingly, the positively charged MPTMA-AuNPs showed the lowest Ka for BSA, indicating that electrostatic interactions are likely not the primary driving force in binding of BSA to these small AuNPs. Ka values at 25 °C for MHA, MEEE, and MPTMA-AuNPs were 5.2 ± 0.2 × 107, 3.7 ± 0.2 × 107, and 3.3 ± 0.16 × 107 M-1 in water, respectively. Fluorescence quenching titrations performed in 100 mM NaCl resulted in lower Ka values for the charged AuNPs, while the Ka value for the MEEE-AuNPs remained unchanged. Measurement of the hydrodynamic diameter (Dh) by dynamic light scattering (DLS) suggests that adsorption of 1-2 BSA molecules is sufficient to saturate the AuNP surface. DLS and negative-stain TEM images indicate that, despite the lower observed Ka values, the binding of MPTMA-AuNPs to BSA likely induces significant protein misfolding and may lead to extensive BSA aggregation at specific BSA:AuNP molar ratios.
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Affiliation(s)
- Jennifer
L. Hanigan-Diebel
- Chemistry
Department, Central Washington University, 400 East University Way, Ellensburg, Washington 98926, United States
| | - Robert J. Costin
- Department
of Physical and Environmental Sciences, Colorado Mesa University, 1100 North Ave, Grand Junction, Colorado 81501, United States
| | - Logan C. Myers
- Department
of Physical and Environmental Sciences, Colorado Mesa University, 1100 North Ave, Grand Junction, Colorado 81501, United States
| | - Christopher I. Vandermeer
- Department
of Physical and Environmental Sciences, Colorado Mesa University, 1100 North Ave, Grand Junction, Colorado 81501, United States
| | - Miles S. Willis
- Department
of Physical and Environmental Sciences, Colorado Mesa University, 1100 North Ave, Grand Junction, Colorado 81501, United States
| | - Kiran Takhar
- Chemistry
Department, Central Washington University, 400 East University Way, Ellensburg, Washington 98926, United States
| | - Ogechukwu V. Odinakachukwu
- Chemistry
Department, Central Washington University, 400 East University Way, Ellensburg, Washington 98926, United States
| | - Matthias G. Carroll
- Chemistry
Department, Central Washington University, 400 East University Way, Ellensburg, Washington 98926, United States
| | - Jarrod E. Schiffbauer
- Department
of Physical and Environmental Sciences, Colorado Mesa University, 1100 North Ave, Grand Junction, Colorado 81501, United States
| | - Samuel E. Lohse
- Chemistry
Department, Central Washington University, 400 East University Way, Ellensburg, Washington 98926, United States
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2
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Dillion Lima Cavalcanti I, Humberto Xavier Junior F, Stela Santos Magalhães N, Cajubá de Britto Lira Nogueira M. ISOTHERMAL TITRATION CALORIMETRY (ITC) AS A PROMISING TOOL IN PHARMACEUTICAL NANOTECHNOLOGY. Int J Pharm 2023; 641:123063. [PMID: 37209790 DOI: 10.1016/j.ijpharm.2023.123063] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2023] [Revised: 05/10/2023] [Accepted: 05/13/2023] [Indexed: 05/22/2023]
Abstract
Isothermal titration calorimetry (ITC) is a technique for evaluating the thermodynamic profiles of connection between two molecules, allowing the experimental design of nanoparticles systems with drugs and/or biological molecules. Taking into account the relevance of ITC, we conducted, therefore, an integrative revision of the literature, from 2000 to 2023, on the main purposes of using this technique in pharmaceutical nanotechnology. The search were carried out in the Pubmed, Sciencedirect, Web of Science, and Scifinder databases using the descriptors "Nanoparticles", "Isothermal Titration Calorimetry", and "ITC". We have observed that the ITC technique has been increasingly used in pharmaceutical nanotechnology, seeking to understand the interaction mechanisms in the formation of nanoparticles. Additionally, to understand the behavior of nanoparticles with biological materials (proteins, DNA, cell membranes, among others), thereby helping to understand the behavior of nanocarriers in vivo studies. As a contribution, we intended to reveal the importance of ITC in the laboratory routine, which is itself a quick and easy technique to obtain relevant results that help to optimize the nanosystems formulation process.
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Affiliation(s)
- Iago Dillion Lima Cavalcanti
- Keizo Asami Institute (iLIKA), Federal University of Pernambuco (UFPE), Av. Prof. Moraes Rego - Cidade Universitária, Recife - PE, Brazil
| | - Francisco Humberto Xavier Junior
- Keizo Asami Institute (iLIKA), Federal University of Pernambuco (UFPE), Av. Prof. Moraes Rego - Cidade Universitária, Recife - PE, Brazil; Department of Pharmacy, Pharmaceutical Biotechnology Laboratory (BioTecFarm), Federal University of Paraíba (UFPB), Campus I Lot. Cidade Universitaria, PB, 58051-900, Brazil
| | - Nereide Stela Santos Magalhães
- Keizo Asami Institute (iLIKA), Federal University of Pernambuco (UFPE), Av. Prof. Moraes Rego - Cidade Universitária, Recife - PE, Brazil
| | - Mariane Cajubá de Britto Lira Nogueira
- Keizo Asami Institute (iLIKA), Federal University of Pernambuco (UFPE), Av. Prof. Moraes Rego - Cidade Universitária, Recife - PE, Brazil; Laboratory of Nanotechnology, Biotechnology and Cell Culture (NanoBioCel), Academic Center of Vitória, Federal University of Pernambuco (CAV/UFPE), R. Alto do Reservatório - Alto José Leal, Vitória de Santo Antão - PE, 55608-680, Brazil.
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3
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Peng Y, Shen Y, Ge M, Pan Z, Chen W, Gong B. Efficient extraction of heavy metals from collagens by sulfonated polystyrene nanospheres. Food Chem 2019; 275:377-384. [DOI: 10.1016/j.foodchem.2018.09.111] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2018] [Revised: 08/26/2018] [Accepted: 09/18/2018] [Indexed: 11/30/2022]
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4
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Chen Z, McDonald S, FitzGerald P, Warr GG, Atkin R. Small angle neutron scattering study of the conformation of poly(ethylene oxide) dissolved in deep eutectic solvents. J Colloid Interface Sci 2017; 506:486-492. [DOI: 10.1016/j.jcis.2017.07.068] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2017] [Revised: 07/11/2017] [Accepted: 07/13/2017] [Indexed: 10/19/2022]
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5
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Bertolino V, Cavallaro G, Lazzara G, Milioto S, Parisi F. Biopolymer-Targeted Adsorption onto Halloysite Nanotubes in Aqueous Media. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2017; 33:3317-3323. [PMID: 28276693 DOI: 10.1021/acs.langmuir.7b00600] [Citation(s) in RCA: 63] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Studies on the adsorption of biopolymers onto halloysite nanotubes (HNTs) in water were conducted. Three polymers with different charges-anionic (pectin), neutral (hydroxypropyl cellulose), and cationic (chitosan)-were chosen. The thermodynamic parameters for the adsorption of polymers onto the HNT surface were determined by isothermal titration calorimetry (ITC). The experimental data were interpreted based on a Langmuir adsorption model. The standard variations in free energy, enthalpy, and entropy of the process were obtained and discussed. Turbidimetry was used to evaluate the stability of functionalized nanoparticles in water. The ζ-potential clarified the surface charge properties of functionalized nanotubes upon polymer adsorption. The interaction of modified nanotubes with polymers led to the formation of a colloidal system with tunable stability and surface properties, which offers different perspectives on new applications of these dispersions, such as carriers for substances to be released in response to external stimuli.
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Affiliation(s)
- Vanessa Bertolino
- Department of Physics and Chemistry, Università degli Studi di Palermo , Viale delle Scienze, pad. 17, 90128 Palermo, Italy
| | - Giuseppe Cavallaro
- Department of Physics and Chemistry, Università degli Studi di Palermo , Viale delle Scienze, pad. 17, 90128 Palermo, Italy
| | - Giuseppe Lazzara
- Department of Physics and Chemistry, Università degli Studi di Palermo , Viale delle Scienze, pad. 17, 90128 Palermo, Italy
| | - Stefana Milioto
- Department of Physics and Chemistry, Università degli Studi di Palermo , Viale delle Scienze, pad. 17, 90128 Palermo, Italy
| | - Filippo Parisi
- Department of Physics and Chemistry, Università degli Studi di Palermo , Viale delle Scienze, pad. 17, 90128 Palermo, Italy
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6
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Zou H, Wang X. Adsorption of Silica Nanoparticles onto Poly(N-vinylpyrrolidone)-Functionalized Polystyrene Latex. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2017; 33:1471-1477. [PMID: 28112949 DOI: 10.1021/acs.langmuir.6b03977] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
This paper presents a more general method to prepare silica-coated polystyrene (PS) particles with minimal excess silica by adsorption, highlighting the role of poly(N-vinylpyrrolidone) (PVP). The method is based on the addition of small silica nanoparticles onto submicrometer-sized near-monodisperse polymer latex particles under the conditions of monolayer silica coverage of the latex surface. Either a cationic or an anionic initiator could be used in the PVP-involved emulsion polymerization to prepare PS particles, and the adsorption was conducted successfully either under acidic or basic conditions. Neither a cationic initiator nor a basic condition is a prerequisite for the adsorption process, which should be related to the much stronger interaction between PVP and the silica surface. This method is expected to substantially extend the adsorption conditions of polymer-silica colloidal nanocomposite syntheses.
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Affiliation(s)
- Hua Zou
- School of Materials Science and Engineering, University of Shanghai for Science and Technology , 516 Jungong Road, Shanghai 200093, China
| | - Xia Wang
- School of Materials Science and Engineering, University of Shanghai for Science and Technology , 516 Jungong Road, Shanghai 200093, China
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7
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Biomolecule–nanoparticle interactions: Elucidation of the thermodynamics by isothermal titration calorimetry. Biochim Biophys Acta Gen Subj 2016; 1860:945-956. [DOI: 10.1016/j.bbagen.2016.01.027] [Citation(s) in RCA: 71] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2015] [Revised: 01/29/2016] [Accepted: 01/30/2016] [Indexed: 12/18/2022]
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8
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Spataro G, Dazzazi A, Fortuny S, Champouret Y, Coppel Y, Rubio-Garcia J, Bouhaouss A, Gauffre F, Kahn ML. Insight into the Role of Ligands in the Yellow Luminescence of Zinc Oxide Nanocrystals. Eur J Inorg Chem 2016. [DOI: 10.1002/ejic.201501186] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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9
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De Roo J, De Keukeleere K, Hens Z, Van Driessche I. From ligands to binding motifs and beyond; the enhanced versatility of nanocrystal surfaces. Dalton Trans 2016; 45:13277-83. [DOI: 10.1039/c6dt02410f] [Citation(s) in RCA: 78] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Surface chemistry bridges the gap between nanocrystal synthesis and their applications.
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Affiliation(s)
- J. De Roo
- Department of Inorganic and Physical Chemistry
- Ghent University
- 9000 Gent
- Belgium
| | - K. De Keukeleere
- Department of Inorganic and Physical Chemistry
- Ghent University
- 9000 Gent
- Belgium
| | - Z. Hens
- Department of Inorganic and Physical Chemistry
- Ghent University
- 9000 Gent
- Belgium
| | - I. Van Driessche
- Department of Inorganic and Physical Chemistry
- Ghent University
- 9000 Gent
- Belgium
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10
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Sun CJ, Sun LZ, Sun XX. Graphical Evaluation of the Favorability of Adsorption Processes by Using Conditional Langmuir Constant. Ind Eng Chem Res 2013. [DOI: 10.1021/ie401571p] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/07/2022]
Affiliation(s)
- Cheng-Jun Sun
- College
of Materials and Textile Engineering, Jiaxing Univesity, Jiaxing 314001, China
| | - Ling-Zhi Sun
- Institute of Bioscience
and Technology, Yancheng Teachers University, Yancheng 224051, China
| | - Xian-Xiang Sun
- School of Petrochemical Engineering, Changzhou University, Changzhou 213164, China
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11
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Characterization of Cationic Polyelectrolytes Adsorption to an Anionic Emulsion via Zeta-Potential and Microcalorimetry. J SURFACTANTS DETERG 2013. [DOI: 10.1007/s11743-013-1522-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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12
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Interaction between poly (ethylene oxide) and silica nanoparticles in dilute solutions. CHINESE JOURNAL OF POLYMER SCIENCE 2013. [DOI: 10.1007/s10118-013-1321-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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13
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Cooper CL, Cosgrove T, van Duijneveldt JS, Murray M, Prescott SW. Colloidal particles in competition for stabilizer: a solvent relaxation NMR study of polymer adsorption and desorption. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2012; 28:16588-16595. [PMID: 23137265 DOI: 10.1021/la303864h] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
The competitive adsorption of poly(vinylpyrrolidone) onto silica and alumina-modified silica particles was studied using solvent relaxation nuclear magnetic resonance. The additive nature of the measured relaxation rate enabled predictions to be made of the relaxation rate in different polymer adsorption scenarios. Preferential adsorption of the poly(vinylpyrrolidone) onto the unmodified silica particles occurred when there was insufficient polymer in the system to coat the entire available surface area. Desorption was also found to occur when the polymer was initially adsorbed upon the alumina-modified particle and silica particles were added.
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Affiliation(s)
- Catherine L Cooper
- School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, UK.
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14
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Mota JA, Chagas RA, Vieira EFS, Cestari AR. Synthesis and characterization of a novel fish scale-immobilized chitosan adsorbent--preliminary features of dichlorophenol sorption by solution calorimetry. JOURNAL OF HAZARDOUS MATERIALS 2012; 229-230:346-353. [PMID: 22771344 DOI: 10.1016/j.jhazmat.2012.06.010] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/27/2012] [Revised: 06/04/2012] [Accepted: 06/07/2012] [Indexed: 06/01/2023]
Abstract
Brazilian Corvina fish scales were cross linked with polyglutaraldehyde and chemically modified with chitosan gel. Characterization has pointed that chitosan has good and stable adhesion on the fish scales. The sorption of dichlorophenol-2,6-indophenol (DPI) on the novel material was studied by isothermal solution calorimetry. The non-symmetric shapes of the calorimetric plots indicate that the DPI sorption sites of the adsorbent are not energetically uniform. The enthalpies of the DPI sorption processes were highly exothermic (from -536.7 to -50.9 kJ mol(-1)). The analysis of both the characterization of the materials and the calorimetric results has suggested that the interactions at the fish scales/DPI interface are due to surface reactions. The present work underlines the excellent features of the new fish scale-based adsorbent for use in phenol sorption applications at solid/solution interfaces.
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Affiliation(s)
- Jackeline A Mota
- Department of Materials Science/CCET, Federal University of Sergipe, CEP 49100-000, São Cristóvão, Sergipe, Brazil
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15
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van Gruijthuijsen K, Rufier C, Phou T, Obiols-Rabasa M, Stradner A. Light and neutron scattering study of PEG-oleate and its use in emulsion polymerization. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2012; 28:10381-10388. [PMID: 22708656 DOI: 10.1021/la301191n] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Steric stabilization of colloids forms a robust mechanism to obtain colloids that are stable in a variety of environments, and that can be used to study the phase behavior of hard or soft spheres. We report the synthesis of sterically stabilized colloids in an aqueous environment using readily dissolvable surfactants, with an unsaturated hydrophobic tail. We synthesized a new surfactant by esterification of a poly(ethylene glycol) (PEG) chain of 4.1 kg/mol with oleic acid, called PEG4OA. The micellization of PEG4OA was characterized by light and neutron scattering, which yielded values for the aggregation number and the overall size that are in excellent agreement with a comparable surfactant with a saturated octadecane chain, Brij 700. We successfully used PEG4OA in the emulsion polymerization of polystyrene colloids. In comparison with the smaller surfactant Tween 80, PEG4OA yielded smaller colloids with radii around 50 nm, and the addition of 1-dodecanethiol reduced the formation of aggregates during the synthesis. A contrast variation study with small angle neutron scattering (SANS) showed that a dense PEG layer was grafted to the colloid surface.
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Affiliation(s)
- Kitty van Gruijthuijsen
- Adolphe Merkle Institute, University of Fribourg, Rte de l'ancienne Papeterie 1, CH-1723 Marly, Switzerland
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16
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Ghai R, Falconer RJ, Collins BM. Applications of isothermal titration calorimetry in pure and applied research--survey of the literature from 2010. J Mol Recognit 2012; 25:32-52. [PMID: 22213449 DOI: 10.1002/jmr.1167] [Citation(s) in RCA: 117] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Isothermal titration calorimetry (ITC) is a biophysical technique for measuring the formation and dissociation of molecular complexes and has become an invaluable tool in many branches of science from cell biology to food chemistry. By measuring the heat absorbed or released during bond formation, ITC provides accurate, rapid, and label-free measurement of the thermodynamics of molecular interactions. In this review, we survey the recent literature reporting the use of ITC and have highlighted a number of interesting studies that provide a flavour of the diverse systems to which ITC can be applied. These include measurements of protein-protein and protein-membrane interactions required for macromolecular assembly, analysis of enzyme kinetics, experimental validation of molecular dynamics simulations, and even in manufacturing applications such as food science. Some highlights include studies of the biological complex formed by Staphylococcus aureus enterotoxin C3 and the murine T-cell receptor, the mechanism of membrane association of the Parkinson's disease-associated protein α-synuclein, and the role of non-specific tannin-protein interactions in the quality of different beverages. Recent developments in automation are overcoming limitations on throughput imposed by previous manual procedures and promise to greatly extend usefulness of ITC in the future. We also attempt to impart some practical advice for getting the most out of ITC data for those researchers less familiar with the method.
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Affiliation(s)
- Rajesh Ghai
- Institute for Molecular Bioscience (IMB), University of Queensland, St. Lucia, Queensland, 4072, Australia
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17
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Moura KO, Vieira EFS, Cestari AR. Poly(glutaraldehyde)-stabilized fish scale fibrillar collagen-some features of a new material for heavy metal sorption. J Appl Polym Sci 2011. [DOI: 10.1002/app.35398] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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18
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Yaremko ZM, Tkachenko NG, Fedushinskaya LB. Adsorption of polymethacrylic acid from aqueous solutions on disperse titanium dioxide. RUSSIAN JOURNAL OF PHYSICAL CHEMISTRY A 2011. [DOI: 10.1134/s0036024411100323] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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19
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Ruiz-Hitzky E, Aranda P, Darder M, Ogawa M. Hybrid and biohybrid silicate based materials: molecular vs. block-assembling bottom–up processes. Chem Soc Rev 2011; 40:801-28. [DOI: 10.1039/c0cs00052c] [Citation(s) in RCA: 185] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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20
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McFarlane NL, Wagner NJ, Kaler EW, Lynch ML. Poly(ethylene oxide) (PEO) and poly(vinyl pyrolidone) (PVP) induce different changes in the colloid stability of nanoparticles. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2010; 26:13823-13830. [PMID: 20684552 DOI: 10.1021/la101907s] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
The phase behavior of model polymer-colloid mixtures is measured for solutions approaching the "protein limit", that is, when the radius of gyration of the polymer (R(g)) is greater than or approximately equal to the radius of the colloid (R). Cationic nanoparticles are mixed with poly(ethylene oxide) (PEO) or poly(vinyl pyrolidone) (PVP) at size ratios of R(g)/R = 0.7 and 1.8. The addition of PEO to stable nanoparticle dispersions leads to depletion flocculation in both deionized water and buffer solutions. The instability mechanism for the PVP-nanoparticle system depends on the suspension medium. In water, bridging occurs below the saturation adsorption of PVP, whereas depletion phase separation is evident at concentrations exceeding those necessary to saturate the particle surface. In acidic buffer, PVP addition results in depletion phase separation. The difference between bridging and depletion is distinguished by both visual appearances and rheological measurements. There is no trend (within error bars) in the polymer concentration required to induce instability with increasing R(g)/R in contrast with theoretical predictions. This is most likely due to adsorption of polymer onto the particle surface.
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Affiliation(s)
- Naa Larteokor McFarlane
- Center for Molecular and Engineering Thermodynamics, Department of Chemical Engineering, University of Delaware, Newark, Delaware 19716, USA
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