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Wanselius M, Al-Tikriti Y, Hansson P. Utilizing a microfluidic platform to investigate drug-eluting beads: Binding and release of amphiphilic antidepressants. Int J Pharm 2023; 647:123517. [PMID: 37871867 DOI: 10.1016/j.ijpharm.2023.123517] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2023] [Revised: 09/25/2023] [Accepted: 10/15/2023] [Indexed: 10/25/2023]
Abstract
Drug-eluting beads made of responsive polyelectrolyte networks are used in the treatment of liver cancer. Aggregates of loaded drugs in complex with the networks dissolve upon release, causing swelling of the network. According to a recent mechanism the release and swelling rates are controlled by the mass transport of drug through a depletion layer created in the microgel. We hypothesise that the mechanism, in which the stability of the drug aggregates and the swelling properties of the network play crucial roles, offers means to control the release profile also for other drugs. To test this, we investigated the loading and release properties of amitriptyline, chlorpromazine and doxepin in polyacrylate, hyaluronate and DCbead™ microgels in a microfluidic setup. Loaded drugs could be released to a medium with physiological ionic strength and pH. The binding strength increased with decreasing critical micelle concentration of the drugs and increasing linear charge density of network chains. Microgels displayed drug-rich core/swollen shell coexistence, and swelled during release at a rate in agreement with the depletion layer mechanism, indicating its generality. The results demonstrate the potential of microgels as vehicles for amphiphilic drugs and the usefulness of the microfluidics method for in vitro studies of such systems.
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Affiliation(s)
- Marcus Wanselius
- Department of Medicinal Chemistry, Uppsala University, BMC P.O. Box 574, SE-751 23 Uppsala, Sweden
| | - Yassir Al-Tikriti
- Department of Medicinal Chemistry, Uppsala University, BMC P.O. Box 574, SE-751 23 Uppsala, Sweden
| | - Per Hansson
- Department of Medicinal Chemistry, Uppsala University, BMC P.O. Box 574, SE-751 23 Uppsala, Sweden.
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Moncho-Jordá A, Göth N, Dzubiella J. Liquid structure of bistable responsive macromolecules using mean-field density-functional theory. SOFT MATTER 2023; 19:2832-2846. [PMID: 37000605 DOI: 10.1039/d2sm01523d] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/19/2023]
Abstract
Macromolecular crowding typically applies to biomolecular and polymer-based systems in which the individual particles often feature a two-state folded/unfolded or coil-to-globule transition, such as found for proteins and peptides, DNA and RNA, or supramolecular polymers. Here, we employ a mean-field density functional theory (DFT) of a model of soft and bistable responsive colloids (RCs) in which the size of the macromolecule is explicitly resolved as a degree of freedom living in a bimodal 'Landau' energy landscape (exhibiting big and small states), thus directly responding to the crowding environment. Using this RC-DFT we study the effects of self-crowding on the liquid bulk structure and thermodynamics for different energy barriers and softnesses of the bimodal energy landscape, in conditions close to the coil-to-globule transition. We find substantial crowding effects on the internal distributions, a complex polydispersity behavior, and quasi-universal compression curves for increasing (generalized) packing fractions. Moreover, we uncover distinct signatures of bimodal versus unimodal behavior in the particle compression. Finally, the analysis of the pair structure - derived from the test particle route - reveals that the microstructure of the liquid is quite inhomogeneous due to local depletion effects, tuneable by particle softness.
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Affiliation(s)
- Arturo Moncho-Jordá
- Institute Carlos I for Theoretical and Computational Physics, Facultad de Ciencias, Universidad de Granada, Campus Fuentenueva S/N, 18071 Granada, Spain.
- Departamento de Física Aplicada, Universidad de Granada, Campus Fuentenueva S/N, 18071 Granada, Spain
| | - Nils Göth
- Physikalisches Institut, Albert-Ludwigs-Universität Freiburg, Hermann-Herder Straße 3, D-79104 Freiburg, Germany.
| | - Joachim Dzubiella
- Physikalisches Institut, Albert-Ludwigs-Universität Freiburg, Hermann-Herder Straße 3, D-79104 Freiburg, Germany.
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Wanselius M, Searle S, Rodler A, Tenje M, Abrahmsén-Alami S, Hansson P. Microfluidics Platform for Studies of Peptide – Polyelectrolyte Interaction. Int J Pharm 2022; 621:121785. [DOI: 10.1016/j.ijpharm.2022.121785] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2022] [Revised: 04/12/2022] [Accepted: 04/26/2022] [Indexed: 02/01/2023]
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Al-Tikriti Y, Hansson P. Drug-Induced Phase Separation in Polyelectrolyte Microgels. Gels 2021; 8:gels8010004. [PMID: 35049539 PMCID: PMC8774790 DOI: 10.3390/gels8010004] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2021] [Revised: 12/08/2021] [Accepted: 12/18/2021] [Indexed: 01/28/2023] Open
Abstract
Polyelectrolyte microgels may undergo volume phase transition upon loading and the release of amphiphilic molecules, a process important in drug delivery. The new phase is “born” in the outermost gel layers, whereby it grows inward as a shell with a sharp boundary to the “mother” phase (core). The swelling and collapse transitions have previously been studied with microgels in large solution volumes, where they go to completion. Our hypothesis is that the boundary between core and shell is stabilized by thermodynamic factors, and thus that collapsed and swollen phases should be able to also coexist at equilibrium. We investigated the interaction between sodium polyacrylate (PA) microgel networks (diameter: 400–850 µm) and the amphiphilic drug amitriptyline hydrochloride (AMT) in the presence of NaCl/phosphate buffer of ionic strength (I) 10 and 155 mM. We used a specially constructed microscopy cell and micromanipulators to study the size and internal morphology of single microgels equilibrated in small liquid volumes of AMT solution. To probe the distribution of AMT micelles we used the fluorescent probe rhodamine B. The amount of AMT in the microgel was determined by a spectrophotometric technique. In separate experiments we studied the binding of AMT and the distribution between different microgels in a suspension. We found that collapsed, AMT-rich, and swollen AMT-lean phases coexisted in equilibrium or as long-lived metastable states at intermediate drug loading levels. In single microgels at I = 10 mM, the collapsed phase formed after loading deviated from the core-shell configuration by forming either discrete domains near the gel boundary or a calotte shaped domain. At I = 155 mM, single microgels, initially fully collapsed, displayed a swollen shell and a collapsed core after partial release of the AMT load. Suspensions displayed a bimodal distribution of swollen and collapsed microgels. The results support the hypothesis that the boundary between collapsed and swollen phases in the same microgel is stabilized by thermodynamic factors.
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Affiliation(s)
- Yassir Al-Tikriti
- Department of Pharmacy, Uppsala University, P.O. Box 580, 75123 Uppsala, Sweden;
- Department of Medicinal Chemistry, Uppsala University, P.O. Box 574, 75123 Uppsala, Sweden
| | - Per Hansson
- Department of Pharmacy, Uppsala University, P.O. Box 580, 75123 Uppsala, Sweden;
- Department of Medicinal Chemistry, Uppsala University, P.O. Box 574, 75123 Uppsala, Sweden
- Correspondence: ; Tel.: +46-18-4714027
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Hansson P. Volume Transition and Phase Coexistence in Polyelectrolyte Gels Interacting with Amphiphiles and Proteins. Gels 2020; 6:gels6030024. [PMID: 32823773 PMCID: PMC7558656 DOI: 10.3390/gels6030024] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2020] [Revised: 08/04/2020] [Accepted: 08/06/2020] [Indexed: 11/16/2022] Open
Abstract
Polyelectrolyte gels have the capacity to absorb large amounts of multivalent species of opposite charge from aqueous solutions of low ionic strength, and release them at elevated ionic strengths. The reversibility offers the possibility to switch between “storage” and “release” modes, useful in applications such as drug delivery. The review focuses on systems where so-called volume phase transitions (VPT) of the gel network take place upon the absorption and release of proteins and self-assembling amphiphiles. We discuss the background in terms of thermodynamic driving forces behind complex formation in oppositely charged mixtures, the role played by cross-links in covalent gels, and general aspects of phase coexistence in networks in relation to Gibbs’ phase rule. We also briefly discuss a gel model frequently used in papers covered by the review. After that, we review papers dealing with collapse and swelling transitions of gels in contact with solution reservoirs of macroions and surfactants. Here we describe recent progress in our understanding of the conditions required for VPT, competing mechanisms, and hysteresis effects. We then review papers addressing equilibrium aspects of core–shell phase coexistence in gels in equilibrium. Here we first discuss early observations of phase separated gels and results showing how the phases affect each other. Then follows a review of recent theoretical and experimental studies providing evidence of thermodynamically stable core–shell phase separated states, and detailed analyses of the conditions under which they exist. Finally, we describe the results from investigations of mechanisms and kinetics of the collapse/swelling transitions induced by the loading/release of proteins, surfactants, and amphiphilic drug molecules.
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Affiliation(s)
- Per Hansson
- Department of Pharmacy, Uppsala University, Box 532, SE-75123 Uppsala, Sweden
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Al-Tikriti Y, Hansson P. Drug-Eluting Polyacrylate Microgels: Loading and Release of Amitriptyline. J Phys Chem B 2020; 124:2289-2304. [PMID: 32105083 DOI: 10.1021/acs.jpcb.0c00030] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
We investigated the loading of an amphiphilic drug, amitriptyline hydrochloride (AMT), onto sodium polyacrylate hydrogels at low ionic strength and its release at high ionic strength. The purpose was to show how the self-assembling properties of the drug and the swelling of the gel network influenced the loading/release mechanisms and kinetics, important for the development of improved controlled-release systems for parenteral administration of amphiphilic drugs. Equilibrium studies showed that single microgels (∼100 μm) in a large solution volume underwent a discrete transition between swollen and dense states at a critical drug concentration in the solution. For single macrogels in a small solution volume, the transition progressed gradually with increasing amount of added drug, with swollen and dense phases coexisting in the same gel; in a suspension of microgels, swollen and collapsed particles coexisted. Time-resolved micropipette-assisted microscopy studies showed that drug self-assemblies accumulated in a dense shell enclosing the swollen core during loading and that a dense core was surrounded by a swollen shell during release. The time evolution of the radius of single microgels was determined as functions of liquid flow rate, network size, and AMT concentration in the solution. Mass transport of AMT in the surrounding liquid, and in the dense shell, influenced the deswelling rate during loading. Mass transport in the swollen shell controlled the swelling rate during release. A steady-state kinetic model taking into account drug self-assembly, core-shell phase separation, and microgel volume changes was developed and found to be in semiquantitative agreement with the experimental loading and release data.
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Affiliation(s)
- Yassir Al-Tikriti
- Department of Pharmacy, Uppsala University, Box 580, 751 23 Uppsala, Sweden
| | - Per Hansson
- Department of Pharmacy, Uppsala University, Box 580, 751 23 Uppsala, Sweden
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Single bead investigation of a clinical drug delivery system - A novel release mechanism. J Control Release 2018; 292:235-247. [PMID: 30419268 DOI: 10.1016/j.jconrel.2018.11.011] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2018] [Revised: 11/06/2018] [Accepted: 11/08/2018] [Indexed: 11/22/2022]
Abstract
Microgels, such as polymeric hydrogels, are currently used as drug delivery devices (DDSs) for chemotherapeutics and/or unstable drugs. The clinical DDS DC bead® was studied with respect to loading and release, measured as relative bead-volume, of six amphiphilic molecules in a micropipette-assisted microscopy method. Theoretical models for loading and release was used to increase the mechanistic understanding of the DDS. It was shown that equilibrium loading was independent of amphiphile concentration. The loading model showed that the rate-determining step was diffusion of the molecule from the bulk to the bead surface ('film control'). Calculations with the developed and applied release model on the release kinetics were consistent with the observations, as the amphiphiles distribute unevenly in the bead. The rate determining step of the release was the diffusion of the amphiphile molecule through the developed amphiphile-free depletion layer. The release rate is determined by the diffusivity and the tendency for aggregation of the amphiphile where a weak tendency for aggregation (i.e. a large cacb) lead to faster release. Salt was necessary for the release to happen, but at physiological concentrations the entry of salt was not rate-determining. This study provides valuable insights into the loading to and release from the DDS. Also, a novel release mechanism of the clinically used DDS is suggested.
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Andersson M, Hansson P. Phase Behavior of Salt-Free Polyelectrolyte Gel-Surfactant Systems. J Phys Chem B 2017; 121:6064-6080. [PMID: 28541037 DOI: 10.1021/acs.jpcb.7b02215] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Ionic surfactants tend to collapse the outer parts of polyelectrolyte gels, forming shells that can be used to encapsulate other species including protein and peptide drugs. In this paper, the aqueous phase behavior of covalently cross-linked polyacrylate networks containing sodium ions and dodecyltrimethylammonium ions as counterions is investigated by means of swelling isotherms, dye staining, small-angle X-ray scattering, and confocal Raman spectroscopy. The equilibrium state is approached by letting the networks absorb pure water. With an increasing fraction of surfactant ions, the state of the water-saturated gels is found to change from being swollen and monophasic, via multiphasic states, to collapsed and monophasic. The multiphasic gels have a swollen, micelle-lean core surrounded by a collapsed, micelle-rich shell, or a collapsed phase forming a spheroidal inner shell separating two micelle-lean parts. It is shown that the transition between monophasic and core-shell states can be induced by variation of the osmotic pressure and variation of the charge of the micelles by forming mixed micelles with the nonionic surfactant octaethyleneglycol monododecylether. The experimental data are compared with theoretical predictions of a model derived earlier. In the calculations, the collapsed shell is assumed to be homogeneous, an approximation introduced here and shown to be excellent for a wide range of compositions. The theoretical results highlight the electrostatic and hydrophobic driving forces behind phase separation.
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Affiliation(s)
- Martin Andersson
- Department of Pharmacy, Uppsala University , Box 580, Uppsala SE-75123, Sweden
| | - Per Hansson
- Department of Pharmacy, Uppsala University , Box 580, Uppsala SE-75123, Sweden
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Jidheden C, Hansson P. Single Microgels in Core-Shell Equilibrium: A Novel Method for Limited Volume Studies. J Phys Chem B 2016; 120:10030-42. [PMID: 27581555 DOI: 10.1021/acs.jpcb.6b06086] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The interactions of cationic surfactant dodecyltrimethylammonium bromide and cationic protein cytochrome c with anionic polyacrylate microgels have been investigated in microscopic liquid droplets by means of a micropipette technique at ionic strength 0.01 M and pH 8. Experiments on single microgels in solutions of limited amounts of the surfactant provide the first evidence of microgels in a stable biphasic core-shell state with the surfactant partitioned to the shell. Under the same conditions, the protein is found to distribute uniformly in the microgels. Quantitative data in the form of swelling and binding isotherms are presented and compared with literature data for macrogels and with predictions of a recent gel theory. Theory is found to be in semiquantitative agreement with the experiments. The importance of polyion-mediated attractions between the protein molecules is analyzed theoretically and proposed to explain the continuous but highly cooperative binding isotherms.
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Affiliation(s)
- Claes Jidheden
- Department of Pharmacy, Uppsala University , Box 532, SE-75123 Uppsala, Sweden
| | - Per Hansson
- Department of Pharmacy, Uppsala University , Box 532, SE-75123 Uppsala, Sweden
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Gernandt J, Hansson P. Surfactant-induced core/shell phase equilibrium in hydrogels. J Chem Phys 2016; 144:064902. [DOI: 10.1063/1.4941326] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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Bračič M, Hansson P, Pérez L, Zemljič LF, Kogej K. Interaction of Sodium Hyaluronate with a Biocompatible Cationic Surfactant from Lysine: A Binding Study. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2015; 31:12043-12053. [PMID: 26474215 DOI: 10.1021/acs.langmuir.5b03548] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Mixtures of natural and biodegradable surfactants and ionic polysaccharides have attracted considerable research interest in recent years because they prosper as antimicrobial materials for medical applications. In the present work, interactions between the lysine-derived biocompatible cationic surfactant N(ε)-myristoyl-lysine methyl ester, abbreviated as MKM, and the sodium salt of hyaluronic acid (NaHA) are investigated in aqueous media by potentiometric titrations using the surfactant-sensitive electrode and pyrene-based fluorescence spectroscopy. The critical micelle concentration in pure surfactant solutions and the critical association concentration in the presence of NaHA are determined based on their dependence on the added electrolyte (NaCl) concentration. The equilibrium between the protonated (charged) and deprotonated (neutral) forms of MKM is proposed to explain the anomalous binding isotherms observed in the presence of the polyelectrolyte. The explanation is supported by theoretical model calculations of the mixed-micelle equilibrium and the competitive binding of the two MKM forms to the surface of the electrode membrane. It is suggested that the presence of even small amounts of the deprotonated form can strongly influence the measured electrode response. Such ionic-nonionic surfactant mixtures are a special case of mixed surfactant systems where the amount of the nonionic component cannot be varied independently as was the case for some of the earlier studies.
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Affiliation(s)
- Matej Bračič
- Institute for the Engineering and Design of Materials, University of Maribor , Smetanova 17, 2000 Maribor, Slovenia
| | - Per Hansson
- Department of Pharmacy, Biomedical Centre, Uppsala University , SE-75123 Uppsala, Sweden
| | - Lourdes Pérez
- Department of Chemical and Surfactant Technology, Instituto de Química Avanzada de Cataluña, CSIC , Jordi Girona 18-26, 08034 Barcelona, Spain
| | - Lidija F Zemljič
- Institute for the Engineering and Design of Materials, University of Maribor , Smetanova 17, 2000 Maribor, Slovenia
| | - Ksenija Kogej
- Department of Chemistry and Biochemistry, Faculty of Chemistry and Chemical Technology, University of Ljubljana , Večna pot 113, 1000 Ljubljana, Slovenia
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