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Khanra P, Rajdev P, Das A. Seed-Induced Living Two-Dimensional (2D) Supramolecular Polymerization in Water: Implications on Protein Adsorption and Enzyme Inhibition. Angew Chem Int Ed Engl 2024; 63:e202400486. [PMID: 38265331 DOI: 10.1002/anie.202400486] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2024] [Revised: 01/22/2024] [Accepted: 01/24/2024] [Indexed: 01/25/2024]
Abstract
In biological systems, programmable supramolecular frameworks characterized by coordinated directional non-covalent interactions are widespread. However, only a small number of reports involve pure water-based dynamic supramolecular assembly of artificial π-amphiphiles, primarily due to the formidable challenge of counteracting the strong hydrophobic dominance of the π-surface in water, leading to undesired kinetic traps. This study reveals the pathway complexity in hydrogen-bonding-mediated supramolecular polymerization of an amide-functionalized naphthalene monoimide (NMI) building block with a hydrophilic oligo-oxyethylene (OE) wedge. O-NMI-2 initially produced entropically driven, collapsed spherical particles in water (Agg-1); however, over a span of 72 h, these metastable Agg-1 gradually transformed into two-dimensional (2D) nanosheets (Agg-2), favoured by both entropy and enthalpy contributions. The intricate self-assembly pathways in O-NMI-2 enable us to explore seed-induced living supramolecular polymerization (LSP) in water for controlled synthesis of monolayered 2D assemblies. Furthermore, we demonstrated the nonspecific surface adsorption of a model enzyme, serine protease α-Chymotrypsin (α-ChT), and consequently the enzyme activity, which could be regulated by controlling the morphological transformation of O-NMI-2 from Agg-1 to Agg-2. We delve into the thermodynamic aspects of such shape-dependent protein-surface interactions and unravel the impact of seed-induced LSP on temporally controlling the catalytic activity of α-ChT.
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Affiliation(s)
- Payel Khanra
- School of Applied and Interdisciplinary Sciences, Indian Association for the Cultivation of Science (IACS), 2A & 2B Raja S. C. Mullick Road, Jadavpur, Kolkata, 700032, India
| | - Priya Rajdev
- School of Applied and Interdisciplinary Sciences, Indian Association for the Cultivation of Science (IACS), 2A & 2B Raja S. C. Mullick Road, Jadavpur, Kolkata, 700032, India
| | - Anindita Das
- School of Applied and Interdisciplinary Sciences, Indian Association for the Cultivation of Science (IACS), 2A & 2B Raja S. C. Mullick Road, Jadavpur, Kolkata, 700032, India
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2
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Walkowiak JJ, Nikam R, Ballauff M. Adsorption of Mono- and Divalent Ions onto Dendritic Polyglycerol Sulfate (dPGS) as Studied Using Isothermal Titration Calorimetry. Polymers (Basel) 2023; 15:2792. [PMID: 37447437 DOI: 10.3390/polym15132792] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2023] [Revised: 06/20/2023] [Accepted: 06/21/2023] [Indexed: 07/15/2023] Open
Abstract
The effective charge of highly charged polyelectrolytes is significantly lowered by a condensation of counterions. This effect is more pronounced for divalent ions. Here we present a study of the counterion condensation to dendritic polyglycerol sulfate (dPGS) that consists of a hydrophilic dendritic scaffold onto which sulfate groups are appended. The interactions between the dPGS and divalent ions (Mg2+ and Ca2+) were analyzed using isothermal titration calorimetry (ITC) and showed no ion specificity upon binding, but clear competition between the monovalent and divalent ions. Our findings, in line with the latest theoretical studies, demonstrate that a large fraction of the monovalent ions is sequentially replaced with the divalent ions.
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Affiliation(s)
- Jacek J Walkowiak
- DWI-Leibniz-Institute for Interactive Materials e.V, Forckenbeckstraße 50, 52074 Aachen, Germany
- Institute of Technical and Macromolecular Chemistry, RWTH Aachen University, Worringerweg 2, 52074 Aachen, Germany
- Aachen-Maastricht Institute for Biobased Materials (AMIBM), Maastricht University, Urmonderbaan 22, 6167 RD Geleen, The Netherlands
| | - Rohit Nikam
- Helmholtz-Zentrum Berlin für Materialien und Energie, Hahn-Meitner-Platz 1, 14109 Berlin, Germany
| | - Matthias Ballauff
- Institut für Chemie und Biochemie, Freie Universität Berlin, Taktstraße 3, 14195 Berlin, Germany
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3
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Schulze M, Nie C, Hartmann G, Nickl P, Kulka MW, Ballauff M, Haag R. Virus removal from aqueous environments with polyelectrolyte coatings on a polypropylene fleece. J Appl Polym Sci 2022. [DOI: 10.1002/app.53444] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Maiko Schulze
- Institute of Chemistry and Biochemistry Freie Universität Berlin Berlin Germany
| | - Chuanxiong Nie
- Institute of Chemistry and Biochemistry Freie Universität Berlin Berlin Germany
| | - Greta Hartmann
- Institute of Chemistry and Biochemistry Freie Universität Berlin Berlin Germany
| | - Philip Nickl
- Institute of Chemistry and Biochemistry Freie Universität Berlin Berlin Germany
| | - Michaël W. Kulka
- Institute of Chemistry and Biochemistry Freie Universität Berlin Berlin Germany
| | - Matthias Ballauff
- Institute of Chemistry and Biochemistry Freie Universität Berlin Berlin Germany
| | - Rainer Haag
- Institute of Chemistry and Biochemistry Freie Universität Berlin Berlin Germany
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4
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Khamrui R, Manna RN, Rajdev P, Paul A, Ghosh S. Impact of the Hydrogen-Bonding Functional Group on Hydrogelation of Amphiphilic Naphthalene-diimide Derivatives and Nonspecific Protein Adsorption. ACS APPLIED BIO MATERIALS 2022; 5:5410-5417. [PMID: 36251686 DOI: 10.1021/acsabm.2c00761] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
This manuscript reports the effect of hydrogen-bonding functionality on the supramolecular assembly of naphthalene-diimide (NDI)-derived amphiphilic building blocks in water. All the molecules contain a central NDI chromophore, functionalized with a hydrophilic oligo-oxyethylene (OE) wedge in one arm and a phenyl group on the opposite arm. They differ by a single H-bonding functionality, which links the NDI chromophore and the phenyl moiety. The H-bonding functionalities are amide, thioamide, urea, and urethane in NDI-A, NDI-TA, NDI-U, and NDI-UT, respectively. All of these molecules exhibit π-stacking in water, as evident from their distinct UV/vis absorption spectra when compared to that of the monomeric dye in THF. However, among these four, only NDI-A and NDI-TA show hydrogelation, while the other two precipitate out of the medium. The NDI-A hydrogel also exhibits transient stability and leads to a crystalline precipitate within ∼5 h. Only NDI-TA produces stable transparent hydrogel with the entangled fibrillar morphology that is typical for gelators. Both NDI-A and NDI-TA showed a thermoresponsive property with a lower critical solution temperature of about 41-42 °C. Powder XRD studies show a parallel orientation for NDI-A and an antiparallel orientation for NDI-TA. Computational studies support this experimental observation and indicate that the NDI-A assembly is highly stabilized by strong H-bonding among the amide groups and π-stacking interaction in the parallel orientation. On the other hand, due to weak H-bonding among the thioamide groups, the binding energy of the parallelly oriented NDI-TA was significantly lower and the optimized structure was disordered. Instead, its antiparallel orientation was more stable, with criss-cross aligned H-bonding interactions and π-π interactions between adjacent aromatic rings. The NDI-TA hydrogel with less ordered OE chains on the surface showed prominent adsorption of serum protein BSA. In sharp contrast, NDI-A did not exhibit any notable interaction with BSA, as evident from the ITC studies.
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Affiliation(s)
- Rajesh Khamrui
- School of Applied and Interdisciplinary Sciences, Indian Association for the Cultivation of Science, 2A and 2B Raja S. C. Mullick Road, Kolkata 700032, India
| | - Rabindra Nath Manna
- School of Chemical Sciences, Indian Association for the Cultivation of Science, 2A and 2B Raja S. C. Mullick Road, Kolkata 700032, India
| | - Priya Rajdev
- School of Applied and Interdisciplinary Sciences, Indian Association for the Cultivation of Science, 2A and 2B Raja S. C. Mullick Road, Kolkata 700032, India
| | - Ankan Paul
- School of Chemical Sciences, Indian Association for the Cultivation of Science, 2A and 2B Raja S. C. Mullick Road, Kolkata 700032, India
| | - Suhrit Ghosh
- School of Applied and Interdisciplinary Sciences, Indian Association for the Cultivation of Science, 2A and 2B Raja S. C. Mullick Road, Kolkata 700032, India
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5
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Malicka W, Haag R, Ballauff M. Interaction of Heparin with Proteins: Hydration Effects. J Phys Chem B 2022; 126:6250-6260. [PMID: 35960645 DOI: 10.1021/acs.jpcb.2c04928] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
We present a thermodynamic investigation of the interaction of heparin with lysozyme in the presence of potassium glutamate (KGlu). The binding constant Kb is measured by isothermal titration calorimetry (ITC) in a temperature range from 288 to 310 K for concentrations of KGlu between 25 and 175 mM. The free energy of binding ΔGb derived from Kb is strongly decreasing with increasing concentration of KGlu, whereas the dependence of ΔGb on temperature T is found to be small. The decrease of ΔGb can be explained in terms of counterion release: Binding of lysozyme to the strong polyelectrolyte heparin liberates approximately three of the condensed counterions of heparin, thus increasing the entropy of the system. The dependence of ΔGb on T, on the other hand, is traced back to a change of hydration of the protein and the polyelectrolyte upon complex formation. This dependence is quantitatively described by the parameter Δw that depends on T and vanishes at a characteristic temperature T0. A comparison of the complex formation in the presence of KGlu with the one in the presence of NaCl demonstrates that the parameters related to hydration are changed considerably. The characteristic temperature T0 in the presence of KGlu solutions is considerably smaller than that in the presence of NaCl solutions. The change of specific heat Δcp is found to become more negative with increasing salt concentration: This finding agrees with the model-free analysis by the generalized van't Hoff equation. The entire analysis reveals a small but important change of the free energy of binding by hydration. It shows that these ion-specific Hofmeister effects can be modeled quantitatively in terms of a characteristic temperature T0 and a parameter describing the dependence of Δcp on salt concentration.
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Affiliation(s)
- Weronika Malicka
- Institut für Chemie und Biochemie, Freie Universität Berlin, 14195 Berlin, Germany
| | - Rainer Haag
- Institut für Chemie und Biochemie, Freie Universität Berlin, 14195 Berlin, Germany
| | - Matthias Ballauff
- Institut für Chemie und Biochemie, Freie Universität Berlin, 14195 Berlin, Germany
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Xu X. Development of the Sequential Binding Model and Application for Anticooperative Protein Adsorption onto Charged Dendrimers. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:4102-4110. [PMID: 35324205 DOI: 10.1021/acs.langmuir.2c00173] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
The Langmuir binding model provides one of the simplest and elegant methods for characterizing an adsorption process. Despite its wide-ranging applications, enormous effort has been spent to further integrate complexity onto the standard Langmuir isotherm to incorporate a wide breadth of binding kinetics with the heterogeneity and cooperative effect among ligands and receptors. Here, we use statistical mechanics as a convenient theoretical framework to depict several adsorption processes on a Langmuir-like description. With regard to the system with a two-component mixture of macromolecular binders, we have derived the two-group sequential binding isotherm as an important extension of the original sequential model with more applications, including systems of non-identical binders. Via comparison of the Langmuir equilibrium with the Boltzmann equilibrium, for the first time the binding free energy defined in the Langmuir-like models can be meaningfully compared with simulations. In a practical example of the adsorption between the lysozyme protein and charged dendrimer, we have demonstrated how the calorimetry data of this system could be interpreted by the binding models described above, with an accurate description of the adsorption process, including the cooperative effect and dendrimer heterogeneity. Using the computer simulation as a benchmark, we also reveal and discuss the strengths and limitations of the proposed binding models. The entire analysis serves as a starting point for extending the standard Langmuir model to access more complicated binding processes.
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Affiliation(s)
- Xiao Xu
- School of Chemistry and Chemical Engineering, Nanjing University of Science and Technology, 200 Xiao Ling Wei, Nanjing 210094, P. R. China
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7
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Sorokina SA, Shifrina ZB. Dendrimers as Antiamyloid Agents. Pharmaceutics 2022; 14:pharmaceutics14040760. [PMID: 35456594 PMCID: PMC9031116 DOI: 10.3390/pharmaceutics14040760] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Revised: 03/25/2022] [Accepted: 03/29/2022] [Indexed: 02/07/2023] Open
Abstract
Dendrimer–protein conjugates have significant prospects for biological applications. The complexation changes the biophysical behavior of both proteins and dendrimers. The dendrimers could influence the secondary structure of proteins, zeta-potential, distribution of charged regions on the surface, the protein–protein interactions, etc. These changes offer significant possibilities for the application of these features in nanotheranostics and biomedicine. Based on the dendrimer–protein interactions, several therapeutic applications of dendrimers have emerged. Thus, the formation of stable complexes retains the disordered proteins on the aggregation, which is especially important in neurodegenerative diseases. To clarify the origin of these properties and assess the efficiency of action, the mechanism of protein–dendrimer interaction and the nature and driving force of binding are considered in this review. The review outlines the antiamyloid activity of dendrimers and discusses the effect of dendrimer structures and external factors on their antiamyloid properties.
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8
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Ballauff M. Denaturation of proteins: electrostatic effects vs. hydration. RSC Adv 2022; 12:10105-10113. [PMID: 35424951 PMCID: PMC8968186 DOI: 10.1039/d2ra01167k] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2022] [Accepted: 03/23/2022] [Indexed: 11/25/2022] Open
Abstract
The unfolding transition of proteins in aqueous solution containing various salts or uncharged solutes is a classical subject of biophysics. In many cases, this transition is a well-defined two-stage equilibrium process which can be described by a free energy of transition ΔGu and a transition temperature Tm. For a long time, it has been known that solutes can change Tm profoundly. Here we present a phenomenological model that describes the change of Tm with the solute concentration cs in terms of two effects: (i) the change of the number of correlated counterions Δnci and (ii) the change of hydration expressed through the parameter Δw and its dependence on temperature expressed through the parameter dΔcp/dcs. Proteins always carry charges and Δnci describes the uptake or release of counterions during the transition. Likewise, the parameter Δw measures the uptake or release of water during the transition. The transition takes place in a reservoir with a given salt concentration cs that defines also the activity of water. The parameter Δnci is a measure for the gain or loss of free energy because of the release or uptake of ions and is related to purely entropic effects that scale with ln cs. Δw describes the effect on ΔGu through the loss or uptake of water molecules and contains enthalpic as well as entropic effects that scale with cs. It is related to the enthalpy of transition ΔHu through a Maxwell relation: the dependence of ΔHu on cs is proportional to the dependence of Δw on temperature. While ionic effects embodied in Δnci are independent of the kind of salt, the hydration effects described through Δw are directly related to Hofmeister effects of the various salt ions. A comparison with literature data underscores the general validity of the model. A phenomenological approach to the unfolding transition of proteins is given. The model treats quantitatively the effect of electrostatics as well as of hydration (Hofmeister effects).![]()
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Affiliation(s)
- Matthias Ballauff
- Institut für Chemie und Biochemie, Freie Universität Berlin Takustraße 3 14195 Berlin Germany
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9
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Interaction of Linear Polyelectrolytes with Proteins: Role of Specific Charge-Charge Interaction and Ionic Strength. Biomolecules 2021; 11:biom11091377. [PMID: 34572590 PMCID: PMC8472085 DOI: 10.3390/biom11091377] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2021] [Revised: 09/10/2021] [Accepted: 09/13/2021] [Indexed: 11/26/2022] Open
Abstract
We present a thermodynamic study of the interaction of synthetic, linear polyelectrolytes with bovine serum albumin (BSA). All polyelectrolytes are based on poly(allyl glycidyl ether) which has been modified by polymer-analogous reaction with anionic (-SO3Na), cationic (-NH3Cl or -NHMe2Cl) or zwitterionic groups (-NMe2(CH2)3SO3). While the anionic polymer shows a very weak interaction, the zwitterionic polymer exhibits no interaction with BSA (pI = 4.7) under the applied pH = 7.4, ionic strength (I = 23–80 mM) and temperature conditions (T = 20–37 °C). A strong binding, however, was observed for the polycations bearing primary amino or tertiary dimethyl amino groups, which could be analysed in detail by isothermal titration calorimetry (ITC). The analysis was done using an expression which describes the free energy of binding, ΔGb, as the function of the two decisive variables, temperature, T, and salt concentration, cs. The underlying model splits ΔGb into a term related to counterion release and a term related to water release. While the number of released counter ions is similar for both systems, the release of bound water is more important for the primary amine compared to the tertiary N,N-dimethyl amine presenting polymer. This finding is further traced back to a closer contact of the polymers’ protonated primary amino groups in the complex with oppositely charged moieties of BSA as compared to the bulkier protonated tertiary amine groups. We thus present an investigation that quantifies both driving forces for electrostatic binding, namely counterion release and change of hydration, which contribute to a deeper understanding with direct impact on future advancements in the biomedical field.
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Rajdev P, Ghosh S. Thermodynamic Insights into Protein Adsorption on Supramolecular Assemblies of π-Amphiphiles. J Phys Chem B 2021; 125:8981-8988. [PMID: 34324355 DOI: 10.1021/acs.jpcb.1c03283] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Nonspecific adsorption of proteins on the surface of nanocarriers plays a critical role in their cellular uptake and other biological functions. This article reports vesicular assemblies of two π-amphiphiles (NDI-1 and NDI-2) and thermodynamic aspects of their interaction with bovine serum albumin (BSA). Both contain a hydrophobic naphthalene-diimide (NDI) core and two oligo-oxyethylene (OE) wedges but differ by the presence of the hydrazide group in NDI-1. NDI-2 exhibits a constricted π-stacking and enthalpy-driven adsorption of BSA. In contrast, NDI-1 exhibits a stronger interaction due to enhanced entropy contribution. It is postulated that a tight packing of NDI chromophores in NDI-2 results in an inadequate space in the corona, leading to the dehydration of OE chains, which contributes to the observed enthalpy-driven binding. On the other hand, due to H-bonding along the direction of π-stacking in NDI-1, an enhanced interchromophoric distance provides more space in the shell, resulting in less dehydration of the OE chains, which results in an entropy gain from the BSA binding-induced release of water from the OE chains. Intercalation of an electron-rich pyrene in the electron-deficient NDI-1 stack further reduces the grafting density of the OE chains, resulting in negligible BSA adsorption, similar to a stealth polymer. A correlation can be seen between the thermodynamic landscape of the protein adsorption and the trend of their lower critical solution temperature (LCST), which follows the order NDI-1 + Py < NDI-1 < NDI-2.
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Braatz D, Dimde M, Ma G, Zhong Y, Tully M, Grötzinger C, Zhang Y, Mavroskoufis A, Schirner M, Zhong Z, Ballauff M, Haag R. Toolbox of Biodegradable Dendritic (Poly glycerol sulfate)-SS-poly(ester) Micelles for Cancer Treatment: Stability, Drug Release, and Tumor Targeting. Biomacromolecules 2021; 22:2625-2640. [PMID: 34076415 DOI: 10.1021/acs.biomac.1c00333] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
In this paper, we present well-defined dPGS-SS-PCL/PLGA/PLA micellar systems demonstrating excellent capabilities as a drug delivery platform in light of high stability and precise in vitro and in vivo drug release combined with active targetability to tumors. These six amphiphilic block copolymers were each targeted in two different molecular weights (8 or 16 kDa) and characterized using 1H NMR, gel permeation chromatography (GPC), and elemental analysis. The block copolymer micelles showed monodispersed size distributions of 81-187 nm, strong negative charges between -52 and -41 mV, and low critical micelle concentrations (CMCs) of up to 1.13-3.58 mg/L (134-527 nM). The serum stability was determined as 94% after 24 h. The drug-loading efficiency for Sunitinib ranges from 38 to 83% (8-17 wt %). The release was selectively triggered by glutathione (GSH) and lipase, reaching 85% after 5 days, while only 20% leaching was observed under physiological conditions. Both the in vitro and in vivo studies showed sustained release of Sunitinib over 1 week. CCK-8 assays on HeLa lines demonstrated the high cell compatibility (1 mg/mL, 94% cell viability, 48 h) and the high cancer cell toxicity of Sunitinib-loaded micelles (IC50 2.5 μg/mL). By in vivo fluorescence imaging studies on HT-29 tumor-bearing mice, the targetability of dPGS7.8-SS-PCL7.8 enabled substantial accumulation in tumor tissue compared to nonsulfated dPG3.9-SS-PCL7.8. As a proof of concept, Sunitinib-loaded dPGS-SS-poly(ester) micelles improved the antitumor efficacy of the chemotherapeutic. A tenfold lower dosage of loaded Sunitinib led to an even higher tumor growth inhibition compared to the free drug, as demonstrated in a HeLa human cervical tumor-bearing mice model. No toxicity for the organism was observed, confirming the good biocompatibility of the system.
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Affiliation(s)
- Daniel Braatz
- Institut für Chemie und Biochemie, Freie Universität Berlin, Takustr. 3, 14195 Berlin, Germany
| | - Mathias Dimde
- Institut für Chemie und Biochemie, Freie Universität Berlin, Takustr. 3, 14195 Berlin, Germany
| | - Guoxin Ma
- Institut für Chemie und Biochemie, Freie Universität Berlin, Takustr. 3, 14195 Berlin, Germany
| | - Yinan Zhong
- Department of Pharmaceutical Engineering, China Pharmaceutical University, Nanjing 211198, P. R. China
| | - Michael Tully
- Institut für Chemie und Biochemie, Freie Universität Berlin, Takustr. 3, 14195 Berlin, Germany
| | - Carsten Grötzinger
- Department of Hepatology and Gastroenterology, Charité Universitätsmedizin Berlin, Augustenburger Platz 1, 13353 Berlin, Germany.,German Cancer Consortium (DKTK), Partner Site Berlin, 13353 Berlin, Germany
| | - Yuanyuan Zhang
- Department of Pharmaceutical Engineering, China Pharmaceutical University, Nanjing 211198, P. R. China
| | - Alexandros Mavroskoufis
- Institut für Chemie und Biochemie, Freie Universität Berlin, Takustr. 3, 14195 Berlin, Germany
| | - Michael Schirner
- Institut für Chemie und Biochemie, Freie Universität Berlin, Takustr. 3, 14195 Berlin, Germany
| | - Zhiyuan Zhong
- Biomedical Polymers Laboratory, College of Chemistry, Chemical Engineering and Materials Science, and State Key Laboratory of Radiation Medicine and Protection, Soochow University, Suzhou 215123, P. R. China
| | - Matthias Ballauff
- Institut für Chemie und Biochemie, Freie Universität Berlin, Takustr. 3, 14195 Berlin, Germany
| | - Rainer Haag
- Institut für Chemie und Biochemie, Freie Universität Berlin, Takustr. 3, 14195 Berlin, Germany
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12
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Walkowiak JJ, Ballauff M. Interaction of Polyelectrolytes with Proteins: Quantifying the Role of Water. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2021; 8:2100661. [PMID: 34194953 PMCID: PMC8224434 DOI: 10.1002/advs.202100661] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/17/2021] [Revised: 03/29/2021] [Indexed: 05/11/2023]
Abstract
A theoretical model is presented for the free energy ΔGb of complex formation between a highly charged polyelectrolyte and a protein. The model introduced here comprises both the effect of released counterions and the uptake or release of water molecules during complex formation. The resulting expression for ΔGb is hence capable of describing the dependence of ΔGb on temperature as well as on the concentration of salt in the system: An increase of the salt concentration in the solution increases the activity of the ions and counterion release becomes less effective for binding. On the other hand, an increased salt concentration leads to the decrease of the activity of water in bulk. Hence, release of water molecules during complex formation will be more advantageous and lead to an increase of the magnitude of ΔGb and the binding constant. It is furthermore demonstrated that the release or uptake of water molecules is the origin of the marked enthalpy-entropy cancellation observed during complex formation of polyelectrolytes with proteins. The comparison with experimental data on complex formation between a synthetic (sulfated dendritic polyglycerol) and natural polyelectrolytes (DNA; heparin) with proteins shows full agreement with theory.
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Affiliation(s)
- Jacek J. Walkowiak
- Institut für Chemie und BiochemieFreie Universität BerlinTaktstraße 3Berlin14195Germany
- Aachen‐Maastricht Institute for Biobased MaterialsMaastricht UniversityBrightlands Chemelot Campus, Urmonderbaan 22Geleen6167 RDThe Netherlands
| | - Matthias Ballauff
- Institut für Chemie und BiochemieFreie Universität BerlinTaktstraße 3Berlin14195Germany
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13
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Achazi K, Haag R, Ballauff M, Dernedde J, Kizhakkedathu JN, Maysinger D, Multhaup G. Understanding the Interaction of Polyelectrolyte Architectures with Proteins and Biosystems. Angew Chem Int Ed Engl 2021; 60:3882-3904. [PMID: 32589355 PMCID: PMC7894192 DOI: 10.1002/anie.202006457] [Citation(s) in RCA: 51] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2020] [Indexed: 02/06/2023]
Abstract
The counterions neutralizing the charges on polyelectrolytes such as DNA or heparin may dissociate in water and greatly influence the interaction of such polyelectrolytes with biomolecules, particularly proteins. In this Review we give an overview of studies on the interaction of proteins with polyelectrolytes and how this knowledge can be used for medical applications. Counterion release was identified as the main driving force for the binding of proteins to polyelectrolytes: Patches of positive charge become multivalent counterions of the polyelectrolyte and lead to the release of counterions from the polyelectrolyte and a concomitant increase in entropy. This is shown from investigations on the interaction of proteins with natural and synthetic polyelectrolytes. Special emphasis is paid to sulfated dendritic polyglycerols (dPGS). The Review demonstrates that we are moving to a better understanding of charge-charge interactions in systems of biological relevance. Research along these lines will aid and promote the design of synthetic polyelectrolytes for medical applications.
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Affiliation(s)
- Katharina Achazi
- Institut für Chemie und BiochemieFreie Universität BerlinTakustrasse 314195BerlinGermany
| | - Rainer Haag
- Institut für Chemie und BiochemieFreie Universität BerlinTakustrasse 314195BerlinGermany
| | - Matthias Ballauff
- Institut für Chemie und BiochemieFreie Universität BerlinTakustrasse 314195BerlinGermany
- IRIS AdlershofHumboldt Universität zu BerlinZum Grossen Windkanal 612489BerlinGermany
| | - Jens Dernedde
- Charité-Universitätsmedizin BerlinInstitute of Laboratory MedicineClinical Chemistry, and PathobiochemistryCVK Augustenburger Platz 113353BerlinGermany
| | - Jayachandran N. Kizhakkedathu
- Centre for Blood ResearchDepartment of Pathology and Laboratory MedicineLife Science InstituteDepartment of ChemistrySchool of Biomedical EngineeringUniversity of British ColumbiaVancouverV6T 1Z3Canada
| | - Dusica Maysinger
- Department of Pharmacology and TherapeuticsMcGill UniversityMontrealH3G 1Y6Canada
| | - Gerd Multhaup
- Department of Pharmacology and TherapeuticsMcGill UniversityMontrealH3G 1Y6Canada
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14
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Kang J, Kang AM. Comment on "Physicochemical stimuli as tuning parameters to modulate the structure and stability of nanostructured lipid carriers and release kinetics of encapsulated antileprosy drugs" by R. Kanwar, M. Gradzielski, S. Prevost, G. Kaur, M. S. Appavou and S. K. Mehta, J. Mater. Chem. B, 2019, 7, 6539. J Mater Chem B 2020; 8:10205-10208. [PMID: 33125021 DOI: 10.1039/d0tb01160f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
In a recent article [R. Kanwar et al., J. Mater. Chem. B, 2019, 7(42), 6539-6555], the authors characterized the interactions between drug-loaded nanostructured lipid carriers and bovine serum albumin using thermodynamics. They found that the interactions are spontaneous and driven by entropy. In this present paper, we report our analysis of these results in terms of equilibrium thermodynamics to show that the binding reactions exhibit enthalpy-entropy compensation. Our findings may prove useful for designing nanostructured lipid carriers.
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Affiliation(s)
- Jonghoon Kang
- Department of Biology, Valdosta State University, Valdosta, Georgia, USA.
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15
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Merzougui CE, Roblin P, Aimar P, Venault A, Chang Y, Causserand C, Bacchin P. Pearl-necklace assembly of human serum albumin with the poly(acrylic acid) polyelectrolyte investigated using small angle X-ray scattering (SAXS). SOFT MATTER 2020; 16:9964-9974. [PMID: 33034602 DOI: 10.1039/d0sm01221a] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
In this comprehensive study, the interaction of human serum albumin (HSA) with poly(acrylic acid) (PAA) was explored using small angle X-ray scattering (SAXS) combined with chromatography. The results revealed the formation of a complex between HSA macromolecules and PAA chains but solely under some specific conditions of the ionic strength and pH of the medium. In fact, this binding was found to take place only at pH close to 5 and at low ionic strength (0.15 M). Otherwise, for a higher pH and a salt concentration of 0.75 M the HSA-PAA complex tends to dissociate completely showing the reversibility of the complexation. The assessment of the influence of the HSA/PAA molar ratio on the radius of gyration of the complex suggests that 4 HSA molecules could bind to each 100 kDa PAA chain. In addition, the Porod volume evaluation for the same range of the HSA/PAA ratio confirms this assumption. Finally, an all-atom SAXS modelling study using the BUNCH program was conducted to find a compatible model that fits the HSA-PAA complex scattering data. This model allows us to portray the HSA/PAA complex as a pearl-necklace assembly with 4 HSA molecules on the 100 kDa PAA chain.
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Affiliation(s)
- Charaf E Merzougui
- Laboratoire de Génie Chimique, Université de Toulouse, CNRS, INPT, UPS, Toulouse, France.
| | - Pierre Roblin
- Laboratoire de Génie Chimique, Université de Toulouse, CNRS, INPT, UPS, Toulouse, France.
| | - Pierre Aimar
- Laboratoire de Génie Chimique, Université de Toulouse, CNRS, INPT, UPS, Toulouse, France.
| | - Antoine Venault
- R&D Center for Membrane Technology, Chung Yuan Christian University, Chung Li, Taiwan
| | - Yung Chang
- R&D Center for Membrane Technology, Chung Yuan Christian University, Chung Li, Taiwan
| | - Christel Causserand
- Laboratoire de Génie Chimique, Université de Toulouse, CNRS, INPT, UPS, Toulouse, France.
| | - Patrice Bacchin
- Laboratoire de Génie Chimique, Université de Toulouse, CNRS, INPT, UPS, Toulouse, France.
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16
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Walkowiak JJ, Ballauff M, Zimmermann R, Freudenberg U, Werner C. Thermodynamic Analysis of the Interaction of Heparin with Lysozyme. Biomacromolecules 2020; 21:4615-4625. [DOI: 10.1021/acs.biomac.0c00780] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Jacek Janusz Walkowiak
- Institut für Chemie und Biochemie, Freie Universität Berlin, Takustrasse 3, 14195 Berlin, Germany
| | - Matthias Ballauff
- Institut für Chemie und Biochemie, Freie Universität Berlin, Takustrasse 3, 14195 Berlin, Germany
| | - Ralf Zimmermann
- Leibniz Institute of Polymer Research Dresden, Max Bergmann Center for Biomaterials Dresden, Hohe Str. 6, 01069 Dresden, Germany
| | - Uwe Freudenberg
- Leibniz Institute of Polymer Research Dresden, Max Bergmann Center for Biomaterials Dresden, Hohe Str. 6, 01069 Dresden, Germany
| | - Carsten Werner
- Leibniz Institute of Polymer Research Dresden, Max Bergmann Center for Biomaterials Dresden, Hohe Str. 6, 01069 Dresden, Germany
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17
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Probing the protein corona around charged macromolecules: interpretation of isothermal titration calorimetry by binding models and computer simulations. Colloid Polym Sci 2020. [DOI: 10.1007/s00396-020-04648-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
AbstractIsothermal titration calorimetry (ITC) is a widely used tool to experimentally probe the heat signal of the formation of the protein corona around macromolecules or nanoparticles. If an appropriate binding model is applied to the ITC data, the heat of binding and the binding stoichiometry as well as the binding affinity per protein can be quantified and interpreted. However, the binding of the protein to the macromolecule is governed by complex microscopic interactions. In particular, due to the steric and electrostatic protein–protein interactions within the corona as well as cooperative, charge renormalization effects of the total complex, the application of standard (e.g., Langmuir) binding models is questionable and the development of more appropriate binding models is very challenging. Here, we discuss recent developments in the interpretation of the Langmuir model applied to ITC data of protein corona formation, exemplified for the well-defined case of lysozyme coating highly charged dendritic polyglycerol sulfate (dPGS), and demonstrate that meaningful data can be extracted from the fits if properly analyzed. As we show, this is particular useful for the interpretation of ITC data by molecular computer simulations where binding affinities can be calculated but it is often not clear how to consistently compare them with the ITC data. Moreover, we discuss the connection of Langmuir models to continuum binding models (where no discrete binding sites have to be assumed) and their possible extensions toward the inclusion of leading order cooperative electrostatic effects.
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18
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Walkowiak J, Lu Y, Gradzielski M, Zauscher S, Ballauff M. Thermodynamic Analysis of the Uptake of a Protein in a Spherical Polyelectrolyte Brush. Macromol Rapid Commun 2019; 41:e1900421. [DOI: 10.1002/marc.201900421] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2019] [Revised: 09/19/2019] [Indexed: 12/14/2022]
Affiliation(s)
- Jacek Walkowiak
- Institut für Chemie und BiochemieFreie Universität Berlin Takustraße 3 14195 Berlin Germany
| | - Yan Lu
- Soft Matter and Functional MaterialsHelmholtz‐Zentrum Berlin für Materialen und Energie Hahn‐Meitner‐Platz 1 14109 Berlin Germany
- Institute of ChemistryUniversity of Potsdam 14467 Potsdam Germany
| | - Michael Gradzielski
- Stranski Laboratorium für Physikalische Chemie und Theoretische ChemieInstitut für ChemieStraße des 17. Juni 124Sekr. TC7Technische Universität Berlin D‐10623 Berlin Germany
| | - Stefan Zauscher
- Mechanical Engineering and Material ScienceDuke University Durham NC 27708 USA
| | - Matthias Ballauff
- Soft Matter and Functional MaterialsHelmholtz‐Zentrum Berlin für Materialen und Energie Hahn‐Meitner‐Platz 1 14109 Berlin Germany
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19
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Xu X, Ballauff M. Interaction of Lysozyme with a Dendritic Polyelectrolyte: Quantitative Analysis of the Free Energy of Binding and Comparison to Molecular Dynamics Simulations. J Phys Chem B 2019; 123:8222-8231. [DOI: 10.1021/acs.jpcb.9b07448] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Affiliation(s)
- Xiao Xu
- School of Chemical Engineering, Nanjing University of Science and Technology, 200 Xiao Ling Wei, 210094 Nanjing, P. R. China
| | - Matthias Ballauff
- Soft Matter and Functional Materials, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, 14109 Berlin, Germany
- Institut für Physik, Humboldt-Universität zu Berlin, 12489 Berlin, Germany
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20
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Santos PP, da Silva Nunes A, Exposito de Queiroz AAA, Alencar de Queiroz AA. Interactions of polyglycerol dendrimers with human serum albumin: insights from fluorescence spectroscopy and computational modeling analysis. JOURNAL OF BIOMATERIALS SCIENCE-POLYMER EDITION 2019; 30:1575-1590. [PMID: 31354070 DOI: 10.1080/09205063.2019.1650242] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Polyglycerol dendrimer synthesized from glycerol core (PGLyD) is an interesting reservoir macromolecule for the design of drug delivery systems due to their adequate blood biocompatibility. However, important features as the comprehension of the structural and dynamic characteristics and the interactions of PGLyD with blood proteins receptors remain unresolved. The high affinity and transport of HSA with drugs stimulated the docking simulations utilizing PGLyD as a ligand for the main HSA docking sites IIA and IIIA. HSA and the PGLyD structures were generated with the aid of Autodock Vina and the best conformations were determined by employing molecular docking. The molecular docking results indicate a thermodynamically favorable interaction suggesting a charge transfer complex formation between HSA and PGLyD. The interaction between PGLyD and HSA was investigated by fluorescence and the quenching mechanism of fluorescence of HSA by PGLyD was discussed. The binding constants and the number of binding sites were measured. The values of thermodynamic parameters ΔG, ΔH, and ΔS were calculated at three different temperatures. The experimental and computational results suggest that hydrophobic forces play a major role in stabilizing the HSA-PGLyD complex.
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Affiliation(s)
- Pedro Palhari Santos
- High Voltage Laboratory Prof. Manuel Luís Barreira Martinez (LAT-EFEI)/Institute of Electrical Systems and Energy (ISEE), Federal University of Itajubá-UNIFEI , Itajubá , Brazil
| | - Alexandro da Silva Nunes
- High Voltage Laboratory Prof. Manuel Luís Barreira Martinez (LAT-EFEI)/Institute of Electrical Systems and Energy (ISEE), Federal University of Itajubá-UNIFEI , Itajubá , Brazil
| | | | - Alvaro Antonio Alencar de Queiroz
- High Voltage Laboratory Prof. Manuel Luís Barreira Martinez (LAT-EFEI)/Institute of Electrical Systems and Energy (ISEE), Federal University of Itajubá-UNIFEI , Itajubá , Brazil
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21
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A biophysical insight into structural and functional state of human serum albumin in uremia mimic milieu. Int J Biol Macromol 2019; 131:697-705. [DOI: 10.1016/j.ijbiomac.2019.03.123] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2018] [Revised: 03/19/2019] [Accepted: 03/19/2019] [Indexed: 02/06/2023]
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22
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Xu X, Angioletti-Uberti S, Lu Y, Dzubiella J, Ballauff M. Interaction of Proteins with Polyelectrolytes: Comparison of Theory to Experiment. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:5373-5391. [PMID: 30095921 DOI: 10.1021/acs.langmuir.8b01802] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
We discuss recent investigations of the interaction of polyelectrolytes with proteins. In particular, we review our recent studies on the interaction of simple proteins such as human serum albumin (HSA) and lysozyme with linear polyelectrolytes, charged dendrimers, charged networks, and polyelectrolyte brushes. In all cases discussed here, we combined experimental work with molecular dynamics (MD) simulations and mean-field theories. In particular, isothermal titration calorimetry (ITC) has been employed to obtain the respective binding constants Kb and the Gibbs free energy of binding. MD simulations with explicit counterions but implicit water demonstrate that counterion release is the main driving force for the binding of proteins to strongly charged polyelectrolytes: patches of positive charges located on the surface of the protein become multivalent counterions of the polyelectrolyte, thereby releasing a number of counterions condensed on the polyelectrolyte. The binding Gibbs free energy due to counterion release is predicted to scale with the logarithm of the salt concentration in the system, which is verified by both simulations and experiment. In several cases, namely, for the interaction of proteins with linear polyelectrolytes and highly charged hydrophilic dendrimers, the binding constant could be calculated from simulations to very good approximation. This finding demonstrated that in these cases explicit hydration effects do not contribute to the Gibbs free energy of binding. The Gibbs free energy can also be used to predict the kinetics of protein uptake by microgels for a given system by applying dynamic density functional theory. The entire discussion demonstrates that the direct comparison of theory with experiments can lead to a full understanding of the interaction of proteins with charged polymers. Possible implications for applications, such as drug design, are discussed.
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Affiliation(s)
- Xiao Xu
- School of Chemical Engineering , Nanjing University of Science and Technology , 200 Xiao Ling Wei , Nanjing 210094 , P. R. China
| | - Stefano Angioletti-Uberti
- Department of Materials , Imperial College London , London SW7 2AZ - UK , U.K
- International Research Centre for Soft Matter , Beijing University of Chemical Technology , 100099 Beijing , PR China
| | - Yan Lu
- Soft Matter and Functional Materials , Helmholtz-Zentrum Berlin für Materialien und Energie GmbH , 14109 Berlin , Germany
- Institute of Chemistry , University of Potsdam , 14467 Potsdam , Germany
| | - Joachim Dzubiella
- Soft Matter and Functional Materials , Helmholtz-Zentrum Berlin für Materialien und Energie GmbH , 14109 Berlin , Germany
- Physikalisches Institut , Albert-Ludwigs-Universität , 79104 Freiburg , Germany
| | - Matthias Ballauff
- Soft Matter and Functional Materials , Helmholtz-Zentrum Berlin für Materialien und Energie GmbH , 14109 Berlin , Germany
- Institut für Physik , Humboldt-Universität zu Berlin , 12489 Berlin , Germany
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23
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Umapathi R, Kumar K, Rani GM, Venkatesu P. Influence of biological stimuli on the phase behaviour of a biomedical thermoresponsive polymer: A comparative investigation of hemeproteins. J Colloid Interface Sci 2019; 541:1-11. [DOI: 10.1016/j.jcis.2019.01.062] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2018] [Revised: 01/09/2019] [Accepted: 01/15/2019] [Indexed: 12/31/2022]
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24
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Ran Q, Xu X, Dzubiella J, Haag R, Ballauff M. Thermodynamics of the Binding of Lysozyme to a Dendritic Polyelectrolyte: Electrostatics Versus Hydration. ACS OMEGA 2018; 3:9086-9095. [PMID: 31459043 PMCID: PMC6644519 DOI: 10.1021/acsomega.8b01493] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2018] [Accepted: 07/30/2018] [Indexed: 05/25/2023]
Abstract
The interaction between dendritic polyglycerol sulfate (dPGS) of the second generation and lysozyme was studied by isothermal titration calorimetry (ITC) at different temperatures and salt concentrations. Analysis by ITC showed that 2-3 lysozyme molecules were bound to each dPGS. The resulting binding constant K b and the Gibbs free energy ΔG o decreased markedly with increasing salt concentration but were nearly independent of temperature. The salt dependence of K b led to the conclusion that ca. 3 counterions bound to dPGS were released upon complex formation. The gain in entropy ΔG ci by this counterion-release scales logarithmically with salt concentration and is the main driving force for binding. The temperature dependence of ΔG o was analyzed by the nonlinear van't Hoff plot, taking into account a finite heat capacity change ΔC p,vH. This evaluation led to the binding enthalpy ΔH vH and the binding entropy ΔS vH. Both quantities varied strongly with temperature and even changed sign, but they compensated each other throughout the entire range of temperature. Coarse-grained computer simulations with explicit salt and implicit water were used to obtain the binding free energies that agreed with ITC results. Thus, electrostatic factors were the driving forces for binding whereas all hydration contributions leading to the strongly varying ΔH vH and ΔS vH canceled out. The calorimetric enthalpy ΔH ITC measured directly by ITC differed largely from ΔH vH. ITC measurements done in two buffer systems with different ionization enthalpies revealed that binding was linked to buffer ionization and a partial protonation of the protein.
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Affiliation(s)
- Qidi Ran
- Institute
of Chemistry and Biochemistry, Freie Universität
Berlin, Takustr. 3, 14195 Berlin, Germany
- Institute
of Soft Matter and Functional Materials, Helmholtz-Zentrum Berlin, Hahn-Meitner-Platz 1, 14109 Berlin, Germany
- Multifunctional
Biomaterials for Medicine, Helmholtz Virtual Institute, Kantstr. 55, 14513 Teltow-Seehof, Germany
| | - Xiao Xu
- School
of Chemical Engineering, Nanjing University
of Science and Technology, 200 Xiao Ling Wei, 210094 Nanjing, P. R. China
| | - Joachim Dzubiella
- Institute
of Soft Matter and Functional Materials, Helmholtz-Zentrum Berlin, Hahn-Meitner-Platz 1, 14109 Berlin, Germany
- Multifunctional
Biomaterials for Medicine, Helmholtz Virtual Institute, Kantstr. 55, 14513 Teltow-Seehof, Germany
- Physikalisches
Institut, Albert-Ludwigs-Universität, Hermann-Herder-Str. 3, 79104 Freiburg, Germany
| | - Rainer Haag
- Institute
of Chemistry and Biochemistry, Freie Universität
Berlin, Takustr. 3, 14195 Berlin, Germany
- Multifunctional
Biomaterials for Medicine, Helmholtz Virtual Institute, Kantstr. 55, 14513 Teltow-Seehof, Germany
| | - Matthias Ballauff
- Institute
of Soft Matter and Functional Materials, Helmholtz-Zentrum Berlin, Hahn-Meitner-Platz 1, 14109 Berlin, Germany
- Multifunctional
Biomaterials for Medicine, Helmholtz Virtual Institute, Kantstr. 55, 14513 Teltow-Seehof, Germany
- Institut
für Physik, Humboldt-Universität
zu Berlin, Newtonstr. 15, 12489 Berlin, Germany
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