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Caselli L, Parra-Ortiz E, Micciulla S, Skoda MWA, Häffner SM, Nielsen EM, van der Plas MJA, Malmsten M. Boosting Membrane Interactions and Antimicrobial Effects of Photocatalytic Titanium Dioxide Nanoparticles by Peptide Coating. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2024; 20:e2309496. [PMID: 38402437 DOI: 10.1002/smll.202309496] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/19/2023] [Revised: 01/30/2024] [Indexed: 02/26/2024]
Abstract
Photocatalytic nanoparticles offer antimicrobial effects under illumination due to the formation of reactive oxygen species (ROS), capable of degrading bacterial membranes. ROS may, however, also degrade human cell membranes and trigger toxicity. Since antimicrobial peptides (AMPs) may display excellent selectivity between human cells and bacteria, these may offer opportunities to effectively "target" nanoparticles to bacterial membranes for increased selectivity. Investigating this, photocatalytic TiO2 nanoparticles (NPs) are coated with the AMP LL-37, and ROS generation is found by C11-BODIPY to be essentially unaffected after AMP coating. Furthermore, peptide-coated TiO2 NPs retain their positive ζ-potential also after 1-2 h of UV illumination, showing peptide degradation to be sufficiently limited to allow peptide-mediated targeting. In line with this, quartz crystal microbalance measurements show peptide coating to promote membrane binding of TiO2 NPs, particularly so for bacteria-like anionic and cholesterol-void membranes. As a result, membrane degradation during illumination is strongly promoted for such membranes, but not so for mammalian-like membranes. The mechanisms of these effects are elucidated by neutron reflectometry. Analogously, LL-37 coating promoted membrane rupture by TiO2 NPs for Gram-negative and Gram-positive bacteria, but not for human monocytes. These findings demonstrate that AMP coating may selectively boost the antimicrobial effects of photocatalytic NPs.
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Affiliation(s)
- Lucrezia Caselli
- Department of Pharmacy, University of Copenhagen, Copenhagen, DK-2100, Denmark
- Department of Physical Chemistry 1, Lund University, Lund, SE-22100, Sweden
| | - Elisa Parra-Ortiz
- Department of Pharmacy, University of Copenhagen, Copenhagen, DK-2100, Denmark
- Novonesis, Biologiens Vej 2, Lyngby, DK-2800 Kgs, Denmark
| | - Samantha Micciulla
- Institut Laue-Langevin, CS 20156, Grenoble Cedex 9, 38042, France
- Laboratoire Interdisciplinaire de Physique (LIPhy), Saint Martin d'Hères, 38402, France
- Centre National de la Recherche Scientifique (CNRS), Saint-Martin-d'Hères, Auvergne-Rhône-Alpes, France
| | - Maximilian W A Skoda
- ISIS Pulsed Neutron and Muon Source, Rutherford Appleton Laboratory, Harwell, OX11 0QX, UK
| | - Sara Malekkhaiat Häffner
- Department of Pharmacy, University of Copenhagen, Copenhagen, DK-2100, Denmark
- RISE Research Institutes of Sweden, Malvinas väg 3, Stockholm, 114 86, Sweden
| | | | | | - Martin Malmsten
- Department of Pharmacy, University of Copenhagen, Copenhagen, DK-2100, Denmark
- Department of Physical Chemistry 1, Lund University, Lund, SE-22100, Sweden
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2
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Muthwill MS, Bina M, Paracini N, Coats JP, Merget S, Yorulmaz Avsar S, Messmer D, Tiefenbacher K, Palivan CG. Planar Polymer Membranes Accommodate Functional Self-Assembly of Inserted Resorcinarene Nanocapsules. ACS APPLIED MATERIALS & INTERFACES 2024. [PMID: 38422470 DOI: 10.1021/acsami.3c18687] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/02/2024]
Abstract
Solid-supported polymer membranes (SSPMs) offer great potential in material and life sciences due to their increased mechanical stability and robustness compared to solid-supported lipid membranes. However, there is still a need for expanding the functionality of SSPMs by combining them with synthetic molecular assemblies. In this study, SSPMs served as a flexible matrix for the insertion of resorcinarene monomers and their self-assembly into functional hexameric resorcinarene capsules. Resorcinarene capsules provide a large cavity with affinity specifically for cationic and polyhydroxylated molecules. While the capsules are stable in apolar organic solvents, they disassemble when placed in polar solvents, which limits their application. Here, a solvent-assisted approach was used for copolymer membrane deposition on solid support and simultaneous insertion of the resorcinarene monomers. By investigation of the molecular factors and conditions supporting the codeposition of the copolymer and resorcinarene monomers, a stable hybrid membrane was formed. The hydrophobic domain of the membrane played a crucial role by providing a sufficiently thick and apolar layer, allowing for the self-assembly of the capsules. The capsules were functional inside the membranes by encapsulating cationic guests from the aqueous environment. The amount of resorcinarene capsules in the hybrid membranes was quantified by a combination of quartz-crystal microbalance with dissipation and liquid chromatography-mass spectrometry, while the membrane topography and layer composition were analyzed by atomic force microscopy and neutron reflectometry. Functional resorcinarene capsules inside SSPMs can serve as dynamic sensors and potentially as cross-membrane transporters, thus holding great promise for the development of smart surfaces.
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Affiliation(s)
- Moritz S Muthwill
- Biointerfacing Nanomaterials Group, Department of Chemistry, University of Basel, Mattenstrasse 22, BPR 1096, 4058 Basel, Switzerland
- NCCR Molecular Systems Engineering, Mattenstrasse 22, BPR 1095, 4058 Basel, Switzerland
| | - Maryame Bina
- Biointerfacing Nanomaterials Group, Department of Chemistry, University of Basel, Mattenstrasse 22, BPR 1096, 4058 Basel, Switzerland
| | - Nicolò Paracini
- Institut Laue-Langevin, 71 Avenue des Martyrs, CS 20156, 38042 Grenoble Cedex 9, France
| | - John Peter Coats
- Biointerfacing Nanomaterials Group, Department of Chemistry, University of Basel, Mattenstrasse 22, BPR 1096, 4058 Basel, Switzerland
| | - Severin Merget
- NCCR Molecular Systems Engineering, Mattenstrasse 22, BPR 1095, 4058 Basel, Switzerland
- Department of Chemistry, University of Basel, Mattenstrasse 22, BPR 1096, 4058 Basel, Switzerland
| | - Saziye Yorulmaz Avsar
- Biointerfacing Nanomaterials Group, Department of Chemistry, University of Basel, Mattenstrasse 22, BPR 1096, 4058 Basel, Switzerland
| | - Daniel Messmer
- Biointerfacing Nanomaterials Group, Department of Chemistry, University of Basel, Mattenstrasse 22, BPR 1096, 4058 Basel, Switzerland
| | - Konrad Tiefenbacher
- NCCR Molecular Systems Engineering, Mattenstrasse 22, BPR 1095, 4058 Basel, Switzerland
- Department of Chemistry, University of Basel, Mattenstrasse 22, BPR 1096, 4058 Basel, Switzerland
| | - Cornelia G Palivan
- Biointerfacing Nanomaterials Group, Department of Chemistry, University of Basel, Mattenstrasse 22, BPR 1096, 4058 Basel, Switzerland
- NCCR Molecular Systems Engineering, Mattenstrasse 22, BPR 1095, 4058 Basel, Switzerland
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Liu L, Shen Z, Wang C. Recent advances and new insights on the construction of photocatalytic systems for environmental disinfection. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2024; 353:120235. [PMID: 38310793 DOI: 10.1016/j.jenvman.2024.120235] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2023] [Revised: 01/16/2024] [Accepted: 01/24/2024] [Indexed: 02/06/2024]
Abstract
Photocatalysis, as a sustainable and environmentally friendly green technology, has garnered widespread recognition and application across various fields. Especially its potential in environmental disinfection has been highly valued by researchers. This study commences with foundational research on photocatalytic disinfection technology and provides a comprehensive overview of its current developmental status. It elucidates the complexity of the interface reaction mechanism between photocatalysts and microorganisms, providing valuable insights from the perspectives of materials and microorganisms. This study reviews the latest design and modification strategies (Build heterojunction, defect engineering, and heteroatom doping) for photocatalysts in environmental disinfection. Moreover, this study investigates the research focuses and links in constructing photocatalytic disinfection systems, including photochemical reactors, light sources, and material immobilization technologies. It studies the complex challenges and influencing factors generated by different environmental media during the disinfection process. Simultaneously, a comprehensive review extensively covers the research status of photocatalytic disinfection concerning bacteria, fungi, and viruses. It reveals the observable efficiency differences caused by the microstructure of microorganisms during photocatalytic reactions. Based on these influencing factors, the economy and effectiveness of photocatalytic disinfection systems are analyzed and discussed. Finally, this study summarizes the current application status of photocatalytic disinfection products. The challenges faced by the synthesis and application of future photocatalysts are proposed, and the future development in this field is discussed. The potential for research and innovation has been further emphasized, with the core on improving efficiency, reducing costs, and strengthening the practical application of photocatalysis in environmental disinfection.
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Affiliation(s)
- Liming Liu
- School of Environmental Science and Engineering, Tianjin University, Tianjin, 300350, PR China
| | - Zhurui Shen
- School of Materials Science and Engineering, Nankai University, Tianjin, 300350, PR China.
| | - Can Wang
- School of Environmental Science and Engineering, Tianjin University, Tianjin, 300350, PR China.
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4
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Krupnik L, Joshi P, Kappler A, Flühmann B, Alston AB, Digigow R, Wick P, Neels A. Critical nanomaterial attributes of iron-carbohydrate nanoparticles: Leveraging orthogonal methods to resolve the 3-dimensional structure. Eur J Pharm Sci 2023; 188:106521. [PMID: 37423578 DOI: 10.1016/j.ejps.2023.106521] [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: 01/19/2023] [Revised: 06/08/2023] [Accepted: 07/06/2023] [Indexed: 07/11/2023]
Abstract
Intravenous iron-carbohydrate nanomedicines are widely used to treat iron deficiency and iron deficiency anemia across a wide breadth of patient populations. These colloidal solutions of nanoparticles are complex drugs which inherently makes physicochemical characterization more challenging than small molecule drugs. There have been advancements in physicochemical characterization techniques such as dynamic light scattering and zeta potential measurement, that have provided a better understanding of the physical structure of these drug products in vitro. However, establishment and validation of complementary and orthogonal approaches are necessary to better understand the 3-dimensional physical structure of the iron-carbohydrate complexes, particularly with regard to their physical state in the context of the nanoparticle interaction with biological components such as whole blood (i.e. the nano-bio interface).
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Affiliation(s)
- Leonard Krupnik
- Laboratory for Particles-Biology Interactions, Materials meet Life, Swiss Federal Laboratories for Materials Science and Technology (Empa), St. Gallen, Switzerland; Center for X-ray Analytics, Materials meet Life, Swiss Federal Laboratories for Materials Science and Technology (Empa), St. Gallen, Switzerland; Department of Chemistry, University of Fribourg, Fribourg 1700, Switzerland
| | - Prachi Joshi
- Geomicrobiology, Department of Geosciences, University of Tuebingen, Tuebingen 72076, Germany
| | - Andreas Kappler
- Geomicrobiology, Department of Geosciences, University of Tuebingen, Tuebingen 72076, Germany; Cluster of Excellence: EXC 2124: Controlling Microbes to Fight Infection, Tuebingen 72076, Germany
| | - Beat Flühmann
- CSL Vifor, Flughofstrasse 61, Glattbrug 8152, Switzerland
| | | | | | - Peter Wick
- Laboratory for Particles-Biology Interactions, Materials meet Life, Swiss Federal Laboratories for Materials Science and Technology (Empa), St. Gallen, Switzerland
| | - Antonia Neels
- Center for X-ray Analytics, Materials meet Life, Swiss Federal Laboratories for Materials Science and Technology (Empa), St. Gallen, Switzerland; Department of Chemistry, University of Fribourg, Fribourg 1700, Switzerland
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5
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Perini DA, Parra-Ortiz E, Varó I, Queralt-Martín M, Malmsten M, Alcaraz A. Surface-Functionalized Polystyrene Nanoparticles Alter the Transmembrane Potential via Ion-Selective Pores Maintaining Global Bilayer Integrity. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:14837-14849. [PMID: 36417698 PMCID: PMC9974068 DOI: 10.1021/acs.langmuir.2c02487] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
Although nanoplastics have well-known toxic effects toward the environment and living organisms, their molecular toxicity mechanisms, including the nature of nanoparticle-cell membrane interactions, are still under investigation. Here, we employ dynamic light scattering, quartz crystal microbalance with dissipation monitoring, and electrophysiology to investigate the interaction between polystyrene nanoparticles (PS NPs) and phospholipid membranes. Our results show that PS NPs adsorb onto lipid bilayers creating soft inhomogeneous films that include disordered defects. PS NPs form an integral part of the generated channels so that the surface functionalization and charge of the NP determine the pore conductive properties. The large difference in size between the NP diameter and the lipid bilayer thickness (∼60 vs ∼5 nm) suggests a particular and complex lipid-NP assembly that is able to maintain overall membrane integrity. In view of this, we suggest that NP-induced toxicity in cells could operate in more subtle ways than membrane disintegration, such as inducing lipid reorganization and transmembrane ionic fluxes that disrupt the membrane potential.
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Affiliation(s)
- D. Aurora Perini
- Laboratory
of Molecular Biophysics, Department of Physics, Universitat Jaume I, 12071Castellón, Spain
| | - Elisa Parra-Ortiz
- Department
of Pharmacy, University of Copenhagen, DK-2100Copenhagen, Denmark
| | - Inmaculada Varó
- Institute
of Aquaculture Torre de la Sal (IATS-CSIC), Ribera de Cabanes, 12595Castellón, Spain
| | - María Queralt-Martín
- Laboratory
of Molecular Biophysics, Department of Physics, Universitat Jaume I, 12071Castellón, Spain
| | - Martin Malmsten
- Department
of Pharmacy, University of Copenhagen, DK-2100Copenhagen, Denmark
- Department
of Physical Chemistry 1, University of Lund, SE-22100Lund, Sweden
| | - Antonio Alcaraz
- Laboratory
of Molecular Biophysics, Department of Physics, Universitat Jaume I, 12071Castellón, Spain
- . Tel.: +34 964 72 8044
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6
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Ferrara V, Marchetti M, Alfieri D, Targetti L, Scopelliti M, Pignataro B, Pavone F, Vetri V, Sancataldo G. Blue Light Activated Photodegradation of Biomacromolecules by N-doped Titanium Dioxide in a Chitosan Hydrogel Matrix. J Photochem Photobiol A Chem 2022. [DOI: 10.1016/j.jphotochem.2022.114451] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Parra-Ortiz E, Caselli L, Agnoletti M, Skoda MWA, Li X, Zhao D, Malmsten M. Mesoporous silica as a matrix for photocatalytic titanium dioxide nanoparticles: lipid membrane interactions. NANOSCALE 2022; 14:12297-12312. [PMID: 35960150 DOI: 10.1039/d2nr01958b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
In the present study, we investigate the combined interaction of mesoporous silica (SiO2) and photocatalytic titanium dioxide (TiO2) nanoparticles with lipid membranes, using neutron reflectometry (NR), cryo-transmission electron microscopy (cryo-TEM), fluorescence oxidation assays, dynamic light scattering (DLS), and ζ-potential measurements. Based on DLS, TiO2 nanoparticles were found to display strongly improved colloidal stability at physiological pH of skin (pH 5.4) after incorporation into either smooth or spiky ("virus-like") mesoporous silica nanoparticles at low pH, the latter demonstrated by cryo-TEM. At the same time, such matrix-bound TiO2 nanoparticles retain their ability to destabilize anionic bacteria-mimicking lipid membranes under UV-illumination. Quenching experiments indicated both hydroxyl and superoxide radicals to contribute to this, while NR showed that free TiO2 nanoparticles and TiO2 loaded into mesoporous silica nanoparticles induced comparable effects on supported lipid membranes, including membrane thinning, lipid removal, and formation of a partially disordered outer membrane leaflet. By comparing effects for smooth and virus-like mesoporous nanoparticles as matrices for TiO2 nanoparticles, the interplay between photocatalytic and direct membrane binding effects were elucidated. Taken together, the study outlines how photocatalytic nanoparticles can be readily incorporated into mesoporous silica nanoparticles for increased colloidal stability and yet retain most of their capacity for photocatalytic destabilization of lipid membranes, and with maintained mechanisms for oxidative membrane destabilization. As such, the study provides new mechanistic information to the widely employed, but poorly understood, practice of loading photocatalytic nanomaterials onto/into matrix materials for increased performance.
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Affiliation(s)
- Elisa Parra-Ortiz
- Department of Pharmacy, University of Copenhagen, DK-2100 Copenhagen, Denmark.
| | - Lucrezia Caselli
- Department of Pharmacy, University of Copenhagen, DK-2100 Copenhagen, Denmark.
| | - Monica Agnoletti
- Department of Pharmacy, University of Copenhagen, DK-2100 Copenhagen, Denmark.
| | - Maximilian W A Skoda
- ISIS Pulsed Neutron and Muon Source, Rutherford Appleton Laboratory, OX11 0QX Harwell, Oxfordshire, UK
| | - Xiaomin Li
- Department of Chemistry, Collaborative Innovation Center of Chemistry for Energy Materials, State Key Laboratory of Molecular Engineering of Polymers, Fudan University, 200433 Shanghai, P. R. China
| | - Dongyuan Zhao
- Department of Chemistry, Collaborative Innovation Center of Chemistry for Energy Materials, State Key Laboratory of Molecular Engineering of Polymers, Fudan University, 200433 Shanghai, P. R. China
| | - Martin Malmsten
- Department of Pharmacy, University of Copenhagen, DK-2100 Copenhagen, Denmark.
- Department of Physical Chemistry 1, University of Lund, SE-22100 Lund, Sweden
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Parra-Ortiz E, Malmsten M. Photocatalytic nanoparticles - From membrane interactions to antimicrobial and antiviral effects. Adv Colloid Interface Sci 2022; 299:102526. [PMID: 34610862 DOI: 10.1016/j.cis.2021.102526] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2021] [Revised: 09/24/2021] [Accepted: 09/24/2021] [Indexed: 12/23/2022]
Abstract
As a result of increasing resistance among pathogens against antibiotics and anti-viral therapeutics, nanomaterials are attracting current interest as antimicrobial agents. Such materials offer triggered functionalities to combat challenging infections, based on either direct membrane action, effects of released ions, thermal shock induced by either light or magnetic fields, or oxidative photocatalysis. In the present overview, we focus on photocatalytic antimicrobial effects, in which light exposure triggers generation of reactive oxygen species. These, in turn, cause oxidative damage to key components in bacteria and viruses, including lipid membranes, lipopolysaccharides, proteins, and DNA/RNA. While an increasing body of studies demonstrate that potent antimicrobial effects can be achieved by photocatalytic nanomaterials, understanding of the mechanistic foundation underlying such effects is still in its infancy. Addressing this, we here provide an overview of the current understanding of the interaction of photocatalytic nanomaterials with pathogen membranes and membrane components, and how this translates into antibacterial and antiviral effects.
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Affiliation(s)
- Elisa Parra-Ortiz
- Department of Pharmacy, University of Copenhagen, DK-2100 Copenhagen, Denmark
| | - Martin Malmsten
- Department of Pharmacy, University of Copenhagen, DK-2100 Copenhagen, Denmark; Physical Chemistry 1, University of Lund, S-221 00 Lund, Sweden.
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Bahja J, Dymond MK. Does membrane curvature elastic energy play a role in mediating oxidative stress in lipid membranes? Free Radic Biol Med 2021; 171:191-202. [PMID: 34000382 DOI: 10.1016/j.freeradbiomed.2021.05.021] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/02/2021] [Revised: 05/10/2021] [Accepted: 05/11/2021] [Indexed: 02/06/2023]
Abstract
The effects of oxidative stress on cells are associated with a wide range of pathologies. Oxidative stress is predominantly initiated by the action of reactive oxygen species and/or lipoxygenases on polyunsaturated fatty acid containing lipids. The downstream products are oxidised phospholipids, bioactive aldehydes and a range of Schiff base by-products between aldehydes and lipids, or other biomacromolecules. In this review we assess the impact of oxidative stress on lipid membranes, focusing on the changes that occur to the curvature preference (lipid spontaneous curvature) and elastic properties of membranes, since these biophysical properties modulate phospholipid homeostasis. Studies show that the lipid products of oxidative stress reduce stored curvature elastic energy in membranes. Based upon this observation, we hypothesize that the effects of oxidative stress on lipid membranes will be reduced by compounds that increase stored curvature elastic energy. We find a strong correlation appears across literature studies that we have reviewed, such that many compounds like vitamin E, Curcumin, Coenzyme Q10 and vitamin A show behaviour consistent with this hypothesis. Finally, we consider whether age-related changes in lipid composition represent the homeostatic response of cells to compensate for the accumulation of in vivo lipid oxidation products.
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Affiliation(s)
- Julia Bahja
- Centre for Stress and Age-Related Disease, University of Brighton, Lewes Rd, Brighton, BN2 4GL, UK
| | - Marcus K Dymond
- Centre for Stress and Age-Related Disease, University of Brighton, Lewes Rd, Brighton, BN2 4GL, UK.
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Malekkhaiat Häffner S, Parra-Ortiz E, Skoda MWA, Saerbeck T, Browning KL, Malmsten M. Composition effects on photooxidative membrane destabilization by TiO 2 nanoparticles. J Colloid Interface Sci 2021; 584:19-33. [PMID: 33039680 DOI: 10.1016/j.jcis.2020.09.046] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2020] [Revised: 09/11/2020] [Accepted: 09/12/2020] [Indexed: 11/30/2022]
Abstract
Membrane interactions and photooxidative membrane destabilization of titanium dioxide (TiO2) nanoparticles were investigated, focusing on the effects of membrane composition, notably phospholipid headgroup charge and presence of cholesterol. For this, we employed a battery of state-of-the-art methods for studies of bilayers formed by zwitterionic palmitoyloleoylphosphatidylcholine (POPC) containing also polyunsaturated palmitoylarachidonoylphosphocholine (PAPC), as well as its mixtures with anionic palmitoyloleoylphosphatidylglycerol (POPG) and cholesterol. It was found that the TiO2 nanoparticles display close to zero charge at pH 7.4, resulting in aggregation. At pH 3.4, in contrast, the 6 nm TiO2 nanoparticles are well dispersed due to a strongly positive ζ-potential. Mirroring this pH dependence, TiO2 nanoparticles were observed to bind to negatively charged lipid bilayers at pH 3.4, but much less so at pH 7.4. While nanoparticle binding has some destabilizing effect alone, illumination with ultraviolet (UV) light accentuates membrane destabilization, a result of oxidative stress caused by generated reactive oxygen species (ROS). Neutron reflectivity (NR), quartz crystal microbalance (QCM), and small-angle X-ray scattering (SAXS) results all demonstrate that membrane composition strongly influences membrane interactions and photooxidative destabilization of lipid bilayers. In particular, the presence of anionic POPG makes the bilayers more sensitive to oxidative destabilization, whereas a stabilizing effect was observed in the presence of cholesterol. Also, structural aspects of peroxidation were found to depend strongly on membrane composition, notably the presence of anionic phospholipids. The results show that membrane interactions and UV-induced ROS generation act in concert and need to be considered together to understand effects of lipid membrane composition on UV-triggered oxidative destabilization by TiO2 nanoparticles, e.g., in the context of oxidative damage of bacteria and cells.
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Affiliation(s)
| | - E Parra-Ortiz
- Department of Pharmacy, University of Copenhagen, DK-2100 Copenhagen, Denmark
| | - M W A Skoda
- ISIS Pulsed Neutron and Muon Source, Rutherford Appleton Laboratory, Harwell, Oxfordshire OX11 OQX, UK
| | - T Saerbeck
- Institut Laue-Langevin, CS 20156, 38042 Grenoble Cedex 9, France
| | - K L Browning
- Department of Pharmacy, University of Copenhagen, DK-2100 Copenhagen, Denmark
| | - M Malmsten
- Department of Pharmacy, University of Copenhagen, DK-2100 Copenhagen, Denmark; Department of Physical Chemistry 1, University of Lund, SE-22100 Lund, Sweden
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