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Patel S, McNelles SA, Adronov A, Duhamel J. Intramacromolecular Conformational Changes in Low Generation PAMAM Dendrimers Probed by Pyrene Excimer Formation. J Phys Chem B 2023; 127:8040-8048. [PMID: 37673692 DOI: 10.1021/acs.jpcb.3c04053] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/08/2023]
Abstract
Pyrene excimer formation (PEF) was used to probe the intramacromolecular conformational change experienced by low generation pyrene-labeled PAMAM dendrimers referred to as PyCX-PAMAM-GY, where X (=4, 8, or 12) and Y (=0, 1, or 2) represent the number of atoms in the pyrenyl linker and the dendrimer generation, respectively. Each sample was studied in N,N-dimethylformamide (DMF) and dimethyl sulfoxide (DMSO) with and without 5 mM HCl. Global analysis of the monomer and excimer time-resolved fluorescence decays using the model free analysis (MFA) yielded the average rate constant of excimer formation, ⟨k⟩, which was compared with the local pyrene concentration ([Py]loc) of the PyCX-PAMAM-GY samples calculated by assuming that the oligomeric segments constituting the dendrimer's interior obeyed Gaussian statistics. A notable decrease in ⟨k⟩ was observed upon the addition of 5 mM HCl to the PyCX-PAMAM-GY solutions and was attributed to swelling of the dendrimers resulting from the protonation of the internal tertiary amines. The reversibility of this conformational change could also be monitored via PEF. Solvent differences between DMF and DMSO were accounted for by dividing ⟨k⟩ by kdiff, the bimolecular rate constant for diffusive PEF of a n-hexyl-1-pyrenebutyramide model compound, to yield the ⟨k⟩/kdiff ratio. Comparison between the ⟨k⟩/kdiff ratios obtained for all the PyCX-PAMAM-GY samples with and without 5 mM HCl revealed a 13% increase in the radius of the PAMAM-GY dendrimers upon protonation of their internal tertiary amines in agreement with earlier reports. These experiments illustrate that PEF represents a powerful experimental means to quantitatively probe the intramacromolecular conformational changes of complex macromolecules in solution, in a manner that complements scattering techniques.
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Affiliation(s)
- Sanjay Patel
- Institute for Polymer Research, Waterloo Institute for Nanotechnology, Department of Chemistry, University of Waterloo, 200 University Avenue West, Waterloo, ON N2L 3G1, Canada
| | - Stuart A McNelles
- Department of Chemistry and Chemical Biology, Brockhouse Institute for Materials Research, McMaster University, 1280 Main Street W., Hamilton, ON L8S 4M1, Canada
| | - Alex Adronov
- Department of Chemistry and Chemical Biology, Brockhouse Institute for Materials Research, McMaster University, 1280 Main Street W., Hamilton, ON L8S 4M1, Canada
| | - Jean Duhamel
- Institute for Polymer Research, Waterloo Institute for Nanotechnology, Department of Chemistry, University of Waterloo, 200 University Avenue West, Waterloo, ON N2L 3G1, Canada
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Maity T, Aggarwal A, Dasgupta S, Velachi V, Singha Deb AK, Ali SM, Maiti PK. Efficient Removal of Uranyl Ions Using PAMAM Dendrimer: Simulation and Experiment. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2023; 39:6794-6802. [PMID: 37126805 DOI: 10.1021/acs.langmuir.3c00332] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
In this work, using atomistic molecular dynamics (MD) simulations and polymer-assisted ultrafiltration experiments, we explore the adsorption and removal of uranyl ions from aqueous solutions using poly(amidoamine) (PAMAM) dendrimers. The effects of uranyl ion concentration and the pH of the solution were examined for PAMAM dendrimers of generations 3, 4, and 5. Our simulation results show that PAMAM has a high adsorption capacity for the uranyl ions. The adsorption capacity increases with increasing concentration of uranyl ions for all 3 generations of PAMAM in agreement with experimental findings. We find that the number of uranyl ions bound to PAMAM is significantly higher in acidic solutions (pH < 3) as compared to neutral solutions (pH ∼ 7) for all uranyl ion concentrations. Additionally, we find an increase in the number of adsorbed uranyl ions to PAMAM with the increase in the dendrimer generation. This increase is due to the greater number of binding sites present for higher-generation PAMAM dendrimers. Our simulation study shows that nitrate ions form a solvation shell around uranyl ions, which allows them to bind to PAMAM binding sites, including the amide, amine, and carbonyl groups. In polymer-assisted ultrafiltration (PAUF) experiments, the removal percentage of uranyl ions by G3 PAMAM dendrimer increased from 36.3% to 42.6% as the metal ion concentration increased from 2.1 × 10-5 M to 10.5 × 10-5 M at a pH of 2. Our combined experiment and simulation study suggests that PAMAM is an effective adsorbent for removing uranyl ions from aqueous solutions.
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Affiliation(s)
- Tarun Maity
- Center for Condensed Matter Theory, Department of Physics, Indian Institute of Science, Bangalore 560012, India
| | - Abhishek Aggarwal
- Center for Condensed Matter Theory, Department of Physics, Indian Institute of Science, Bangalore 560012, India
| | - Subhadeep Dasgupta
- Center for Condensed Matter Theory, Department of Physics, Indian Institute of Science, Bangalore 560012, India
| | - Vasumathi Velachi
- PG & Research Department of Physics, Affiliated to Bharathidasan University, Holy Cross College, Tiruchirappalli 620002, India
| | | | - Sk Musharaf Ali
- Chemical Engineering Division, Bhabha Atomic Research Centre, Mumbai 91-400085, India
| | - Prabal K Maiti
- Center for Condensed Matter Theory, Department of Physics, Indian Institute of Science, Bangalore 560012, India
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Michna A, Pomorska A, Ozcan O. Biocompatible Macroion/Growth Factor Assemblies for Medical Applications. Biomolecules 2023; 13:biom13040609. [PMID: 37189357 DOI: 10.3390/biom13040609] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2023] [Revised: 03/24/2023] [Accepted: 03/26/2023] [Indexed: 03/31/2023] Open
Abstract
Growth factors are a class of proteins that play a role in the proliferation (the increase in the number of cells resulting from cell division) and differentiation (when a cell undergoes changes in gene expression becoming a more specific type of cell) of cells. They can have both positive (accelerating the normal healing process) and negative effects (causing cancer) on disease progression and have potential applications in gene therapy and wound healing. However, their short half-life, low stability, and susceptibility to degradation by enzymes at body temperature make them easily degradable in vivo. To improve their effectiveness and stability, growth factors require carriers for delivery that protect them from heat, pH changes, and proteolysis. These carriers should also be able to deliver the growth factors to their intended destination. This review focuses on the current scientific literature concerning the physicochemical properties (such as biocompatibility, high affinity for binding growth factors, improved bioactivity and stability of the growth factors, protection from heat, pH changes or appropriate electric charge for growth factor attachment via electrostatic interactions) of macroions, growth factors, and macroion-growth factor assemblies, as well as their potential uses in medicine (e.g., diabetic wound healing, tissue regeneration, and cancer therapy). Specific attention is given to three types of growth factors: vascular endothelial growth factors, human fibroblast growth factors, and neurotrophins, as well as selected biocompatible synthetic macroions (obtained through standard polymerization techniques) and polysaccharides (natural macroions composed of repeating monomeric units of monosaccharides). Understanding the mechanisms by which growth factors bind to potential carriers could lead to more effective delivery methods for these proteins, which are of significant interest in the diagnosis and treatment of neurodegenerative and civilization diseases, as well as in the healing of chronic wounds.
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Flores-Mejía R, Fragoso-Vázquez MJ, Pérez-Blas LG, Parra-Barrera A, Hernández-Castro SS, Estrada-Pérez AR, Rodrígues J, Lara-Padilla E, Ortiz-Morales A, Correa-Basurto J. Chemical characterization (LC-MS-ESI), cytotoxic activity and intracellular localization of PAMAM G4 in leukemia cells. Sci Rep 2021; 11:8210. [PMID: 33859258 PMCID: PMC8050087 DOI: 10.1038/s41598-021-87560-w] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2020] [Accepted: 03/23/2021] [Indexed: 02/08/2023] Open
Abstract
Generation 4 of polyamidoamine dendrimer (G4-PAMAM) has several biological effects due to its tridimensional globular structure, repetitive branched amides, tertiary amines, and amino-terminal subunit groups liked to a common core. G4-PAMAM is cytotoxic due to its positive charges. However, its cytotoxicity could increase in cancer cells due to the excessive intracellular negative charges in these cells. Furthermore, this work reports G4-PAMAM chemical structural characterization using UHPLC-QTOF-MS/MS (LC-MS) by electrospray ionization to measure its population according to its positive charges. Additionally, the antiproliferative effects and intracellular localization were explored in the HMC-1 and K-562 cell lines by confocal microscopy. The LC-MS results show that G4-PAMAM generated multivalent mass spectrum values, and its protonated terminal amino groups produced numerous positive charges, which allowed us to determine its exact mass despite having a high molecular weight. Additionally, G4-PAMAM showed antiproliferative activity in the HMC-1 tumor cell line after 24 h (IC50 = 16.97 µM), 48 h (IC50 = 7.02 µM) and 72 h (IC50 = 5.98 µM) and in the K-562 cell line after 24 h (IC50 = 15.14 µM), 48 h (IC50 = 14.18 µM) and 72 h (IC50 = 9.91 µM). Finally, our results showed that the G4-PAMAM dendrimers were located in the cytoplasm and nucleus in both tumor cell lines studied.
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Affiliation(s)
- R Flores-Mejía
- Laboratorio 103, Sección de Estudios de Posgrado e Investigación, Escuela Superior de Medicina, Instituto Politécnico Nacional, CDMX, Mexico
| | - M J Fragoso-Vázquez
- Departamento de Química Orgánica, Escuela Nacional de Ciencias Biológicas del Instituto Politécnico Nacional, Ciudad de México, Mexico.
| | - L G Pérez-Blas
- Laboratorio 103, Sección de Estudios de Posgrado e Investigación, Escuela Superior de Medicina, Instituto Politécnico Nacional, CDMX, Mexico
| | - A Parra-Barrera
- Laboratorio de Medicina Regenerativa y Estudios del Cancer, Sección de Estudios de Posgrado e Investigación, Escuela Superior de Medicina, Instituto Politécnico Nacional, CDMX, Mexico
| | - S S Hernández-Castro
- Laboratorio de Diseño y Desarrollo de Nuevos Fármacos e Innovación Biotécnológica (Laboratory for the Design and Development of New Drugs and Biotechnological Innovation), Escuela Superior de Medicina, Instituto Politécnico Nacional, Plan de San Luis y Díaz Mirón, 11340, Ciudad de México, Mexico
| | - A R Estrada-Pérez
- Laboratorio de Diseño y Desarrollo de Nuevos Fármacos e Innovación Biotécnológica (Laboratory for the Design and Development of New Drugs and Biotechnological Innovation), Escuela Superior de Medicina, Instituto Politécnico Nacional, Plan de San Luis y Díaz Mirón, 11340, Ciudad de México, Mexico
| | - J Rodrígues
- CQM - Centro de Química da Madeira, Universidade da Madeira, Campus Universitário da Penteada, 9020-105, Funchal, Portugal
- School of Materials Science and Engineering/Center for Nano Energy Materials, Northwestern Polytechnical University, Xi'an, 710072, China
| | - E Lara-Padilla
- Laboratorio de Bioquímica de la Escuela Superior de Medicina, Instituto Politécnico Nacional, Ciudad de México, Mexico
| | - A Ortiz-Morales
- Laboratorio 103, Sección de Estudios de Posgrado e Investigación, Escuela Superior de Medicina, Instituto Politécnico Nacional, CDMX, Mexico
| | - J Correa-Basurto
- Laboratorio de Diseño y Desarrollo de Nuevos Fármacos e Innovación Biotécnológica (Laboratory for the Design and Development of New Drugs and Biotechnological Innovation), Escuela Superior de Medicina, Instituto Politécnico Nacional, Plan de San Luis y Díaz Mirón, 11340, Ciudad de México, Mexico.
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Flores-Mejía R, Fragoso-Vázquez MJ, Pérez-Blas LG, Parra-Barrera A, Hernández-Castro SS, Estrada-Pérez AR, Rodrígues J, Lara-Padilla E, Ortiz-Morales A, Correa-Basurto J. Chemical characterization (LC–MS–ESI), cytotoxic activity and intracellular localization of PAMAM G4 in leukemia cells. Sci Rep 2021. [DOI: https://doi.org/10.1038/s41598-021-87560-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
AbstractGeneration 4 of polyamidoamine dendrimer (G4-PAMAM) has several biological effects due to its tridimensional globular structure, repetitive branched amides, tertiary amines, and amino-terminal subunit groups liked to a common core. G4-PAMAM is cytotoxic due to its positive charges. However, its cytotoxicity could increase in cancer cells due to the excessive intracellular negative charges in these cells. Furthermore, this work reports G4-PAMAM chemical structural characterization using UHPLC-QTOF-MS/MS (LC–MS) by electrospray ionization to measure its population according to its positive charges. Additionally, the antiproliferative effects and intracellular localization were explored in the HMC-1 and K-562 cell lines by confocal microscopy. The LC–MS results show that G4-PAMAM generated multivalent mass spectrum values, and its protonated terminal amino groups produced numerous positive charges, which allowed us to determine its exact mass despite having a high molecular weight. Additionally, G4-PAMAM showed antiproliferative activity in the HMC-1 tumor cell line after 24 h (IC50 = 16.97 µM), 48 h (IC50 = 7.02 µM) and 72 h (IC50 = 5.98 µM) and in the K-562 cell line after 24 h (IC50 = 15.14 µM), 48 h (IC50 = 14.18 µM) and 72 h (IC50 = 9.91 µM). Finally, our results showed that the G4-PAMAM dendrimers were located in the cytoplasm and nucleus in both tumor cell lines studied.
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Gosika M, Mandal T, Maiti PK. Modulating Interdendrimer Interactions through Surface Adsorption. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2020; 36:5492-5501. [PMID: 32364387 DOI: 10.1021/acs.langmuir.0c00208] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Physical confinement of polymers not only affects their structure but also modifies their effective interaction profiles. In this article, we investigate the nature of graphene-adsorbed poly(amidoamine) (PAMAM) dendrimers' interactions using fully atomistic molecular dynamics simulations. Using the umbrella sampling technique, we calculate the potential of mean force (PMF) profiles for the interaction between two graphene-adsorbed PAMAM dendrimers of generations 3 and 4 as a function of their protonation levels. We find that the attractive PMF profile observed for the interaction between two nonprotonated (high pH) PAMAM dendrimers in bulk becomes repulsive upon adsorption. Also, the repulsive interdendrimer interactions known in bulk for the protonated dendrimers become enhanced for the adsorbed case. We further explain these weakened interactions by explicitly showing that the dendrimer-graphene interaction is an order of magnitude larger than the dendrimer-dendrimer bulk interaction. Using the force integration method, we obtain the contributions from various subinteractions present in the system, that is, dendrimer-water, dendrimer-ions, dendrimer-graphene, and dendrimer-dendrimer to the total PMF. From these contributions, we conclude that the reduced dendrimer-dendrimer interactions in the adsorbed case, as compared to those in bulk, lead to the enhanced repulsive effective interdendrimer interactions. Our PMF profiles fit well with the sum of exponential and Gaussian functions, proposed in the bulk interdendrimer interaction study. We hope the current results provide the microscopic origin of how adsorption weakens the interpolymer interactions in general.
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Affiliation(s)
- Mounika Gosika
- Center for Condensed Matter Theory, Department of Physics, Indian Institute of Science, Bangalore 560012, India
| | - Taraknath Mandal
- Center for Condensed Matter Theory, Department of Physics, Indian Institute of Science, Bangalore 560012, India
- Department of Chemistry, Boston University, 590 Commonwealth Avenue, Boston, Massachusetts 02215, United States
| | - Prabal K Maiti
- Center for Condensed Matter Theory, Department of Physics, Indian Institute of Science, Bangalore 560012, India
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Flexibility and Hydration of Amphiphilic Hyperbranched Arabinogalactan-Protein from Plant Exudate: A Volumetric Perspective. COLLOIDS AND INTERFACES 2018. [DOI: 10.3390/colloids2010011] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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Gosika M, Maiti PK. pH and generation dependent morphologies of PAMAM dendrimers on a graphene substrate. SOFT MATTER 2018; 14:1925-1938. [PMID: 29473069 DOI: 10.1039/c8sm00179k] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The adsorption of PAMAM dendrimers at solid/water interfaces has been extensively studied, and is mainly driven by electrostatic and van der Waals interactions between the substrate and the dendrimers. However, the pH dependence of the adsorption driven predominantly by the van der Waals interactions is poorly explored, although it is crucial for investigating the potentiality of these dendrimers in supercapacitors and surface patterning. Motivated by this aspect, we have studied the adsorption behavior of PAMAM dendrimers of generations 2 (G2) to 5 (G5) with pH and salt concentration variation, on a charge neutral graphene substrate, using fully atomistic molecular dynamics simulations. The instantaneous snapshots from our simulations illustrate that the dendrimers deform significantly from their bulk structures. Based on various structural property calculations, we classify the adsorbed dendrimer morphologies into five categories and map them to a phase diagram. Interestingly, the morphologies we report here have striking analogies with those reported in star-polymer adsorption studies. From the fractional contacts and other structural property analyses we find that the deformations are more pronounced at neutral pH as compared to high and low pH. Higher generation dendrimers resist deformation following the deformation trend, G2 > G3 > G4 > G5 at any given pH level. As the adsorption here is mainly driven by van der Waals interactions, we observe no desorption of the dendrimers as the salt molarity is increased, unlike that reported in the electrostatically driven adsorption studies.
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Affiliation(s)
- Mounika Gosika
- Center for Condensed Matter Theory, Department of Physics, Indian Institute of Science, Bangalore - 560012, India.
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Sean D, Landsgesell J, Holm C. Computer Simulations of Static and Dynamical Properties of Weak Polyelectrolyte Nanogels in Salty Solutions. Gels 2017; 4:E2. [PMID: 30674778 PMCID: PMC6318681 DOI: 10.3390/gels4010002] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2017] [Revised: 12/21/2017] [Accepted: 12/23/2017] [Indexed: 12/02/2022] Open
Abstract
We investigate the chemical equilibria of weak polyelectrolyte nanogels with reaction ensemble Monte Carlo simulations. With this method, the chemical identity of the nanogel monomers can change between neutral or charged following the acid-base equilibrium reaction HA ⇌ A- + H⁺. We investigate the effect of changing the chemical equilibria by modifying the dissociation constant K a . These simulations allow for the extraction of static properties like swelling equilibria and the way in which charge-both monomer and ionic-is distributed inside the nanogel. Our findings reveal that, depending on the value of K a , added salt can either increase or decrease the gel size. Using the calculated mean-charge configurations of the nanogel from the reaction ensemble simulation as a quenched input to coupled lattice-Boltzmann molecular dynamics simulations, we investigate dynamical nanogel properties such as the electrophoretic mobility μ and the diffusion coefficient D.
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Affiliation(s)
- David Sean
- Institute for computational physics, University of Stuttgart, Allmandring 3, 70569 Stuttgart, Germany.
| | - Jonas Landsgesell
- Institute for computational physics, University of Stuttgart, Allmandring 3, 70569 Stuttgart, Germany.
| | - Christian Holm
- Institute for computational physics, University of Stuttgart, Allmandring 3, 70569 Stuttgart, Germany.
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