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Browsing Scopus by Department "Fraunhofer-Institut für Angewandte Polymerforschung IAP"
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Publication3D Printable Hybrid Gel Made of Polymer Surface-Modified Cellulose Nanofibrils Prepared by Surface-Initiated Controlled Radical Polymerization (SI-SET-LRP) and Upconversion Luminescent Nanoparticles( 2023)
;Jiang, Xuehe ;Mietner, Jakob Benedikt ;Harder, Constantin ;Komban, Rajesh ;Chen, Shouzheng ;Strelow, Christian ;Sazama, Uta ;Fröba, Michael ;Gimmler, Christoph ;Müller-Buschbaum, Peter ;Roth, Stephan VolkherNavarro, Julien R.G.A cellulose nanofibril-based hybrid gel material was developed by grafting the polymerized stearyl acrylate (PSA) and upconversion nanoparticles (UCNPs) onto cellulose nanofibrils (CNFs) via Cu0-mediated radical polymerization (SET-LRP) to create a highly cross-linked CNF system. A two-step strategy was exploited to surface-exchange the ligand of the UCNPs from a hydrophobic ligand (oleic acid) to a hydrophilic small-molecule ligand (2-acrylamido-2-methyl-1-propanesulfonic acid, AMPS) and therefore be suitable for SET-LRP. The characteristics and properties of the hybrid material (UCNP-PSA-CNF) were monitored by Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), rheology, X-ray diffraction (XRD), and microscopic analysis. Those characterization techniques prove the efficient modification of the CNF, with the presence of 1.8% UCNPs. The luminescence measurement was carried out using a homebuilt confocal microscope with a 980 nm laser source. The nanostructure of UCNPs and their incorporated CNF species were measured by small-angle X-ray scattering (SAXS). In addition, this CNF-based hybrid gel has decisive rheological properties, such as good viscoelasticity (loss tangent was below 0.35 for the UCNP-PSA-CNF gel, while the PSA-CNF gel reached the highest value of 0.42), shear-thinning behavior, and shape retention, and was successfully applied to three-dimensional (3D) gel printing throughout various 3D print models. -
PublicationA Dual pH- and Light-Responsive Spiropyran-Based Surfactant: Investigations on its Switching Behavior and Remote Control over Emulsion Stability( 2022)
;Bekir, Marek ;Bapolisi, Alain M. ;Titov, Evgenii ;Nußhardt, Fabian ;Nowaczyk, Julius ;Sharma, Anjali ;Saalfrank, Peter ;Santer, Svetlana ;Hartlieb, MatthiasA cationic surfactant containing a spiropyran unit is prepared exhibiting a dual-responsive adjustability of its surface-active characteristics. The switching mechanism of the system relies on the reversible conversion of the non-ionic spiropyran (SP) to a zwitterionic merocyanine (MC) and can be controlled by adjusting the pH value and via light, resulting in a pH-dependent photoactivity: While the compound possesses a pronounced difference in surface activity between both forms under acidic conditions, this behavior is suppressed at a neutral pH level. The underlying switching processes are investigated in detail, and a thermodynamic explanation based on a combination of theoretical and experimental results is provided. This complex stimuli-responsive behavior enables remote-control of colloidal systems. To demonstrate its applicability, the surfactant is utilized for the pH-dependent manipulation of oil-in-water emulsions. -
PublicationA Fibre Optic Temperature Sensor based on Thermoresponsive Polymer( 2023)
;Schilling, Ryan ;Oehrl, AlexanderSchukar, MarcusWe present a temperature sensor based on a polymer exhibiting a Lower Critical Solution Temperature (LCST) in aqueous solution encapsulated in a capillary. Parameters are chosen such that the solution exhibits a cloud point in a temperature range of 30° C to 39° C. The characteristic of thermoresponsive polymers with an LCST, is that above that temperature phase separation of the polymer takes place which leads to a temperature-dependent formation of a cloudy suspension. An optical intensity measurement over the desired temperature range is established by an increase of optical attenuation inside the polymer solution caused by a rising temperature. For our purpose, the polymer capillary is connected to transmitter and receiver via a Polymer Optical Fibre (POF). Our intensity measurement is, to the best of our knowledge, a novel method and can be considered simple when compared to existing fibre-based temperature measurement techniques. Due to the lack of electrical components at the probe, this sensor is suitable for measurements in strong electromagnetic fields and environments for which flying sparks are hazardous, i.e., inflammable fluids or gases. Furthermore, all manufactured sensors share the same temperature dependence and, therefore, are well-suited for comparative measurement, e.g., flow measurement systems. With the given temperature range, a body temperature measurement is also suitable. -
PublicationAggregation-Induced Emission in a Flexible Phosphine Oxide and its Zn(II) Complexes - A Simple Approach to Blue Luminescent Materials( 2023)
;Kirst, Christin ;Knechtel, Fabian ;Fischermeier, David ;Petersen, Jens ;Danaf, Nader Al ;Tietze, Jonathan ;Lamb, Don C. ;Mitric, RolandKaraghiosoff, Konstantin LudmilovEasily accessible blue-emitting materials are in the focus of ongoing research, as they still lack the efficiency and lifetime of their red and green counterparts. The new multidentate phosphine oxide ligands and two respective ZnCl2 complexes presented here combine a straightforward synthesis with high yields and show interesting luminescent properties. The free ligand exhibits blue luminescence in the crystalline state, but not in amorphous films or diluted solution. In contrast, the Zn(II) complexes shows intense blue luminescence in the crystalline state as well as in amorphous thin films and in solution. Fluorescence lifetime imaging microscopy measurements show luminescence lifetimes of 3-6 ns indicative of fluorescence. By combining the experimental data with quantum chemical calculations, we propose a model where the conformation of the molecule is restricted, either via the crystal environment, aggregation, or the steric fixation by the coordinating central atom, blocking the nonradiative relaxation from the excited into the ground electronic state. However, this nonradiative relaxation is still possible in the gas phase via elongation of a P-C bond. These results may provide a general mechanism to explain the luminescence properties in a whole class of organic phosphine oxides. -
PublicationAnti-Cancer Prodrug Cyclophosphamide Exerts Thrombogenic Effects on Human Venous Endothelial Cells Independent of CYP450 Activation - Relevance to Thrombosis( 2023)
;Köhler, Susanne ;Laube, Markus ;Haileka, Vanessa ;Lemm, Sandy ;Majchrzak, Karolina ;Kammerer, Sarah ;Schulz, Christian ;Pietzsch, Jens ;Küpper, Jan-HeinerJung, FriedrichCancer patients are at a very high risk of serious thrombotic events, often fatal. The causes discussed include the detachment of thrombogenic particles from tumor cells or the adverse effects of chemotherapeutic agents. Cytostatic agents can either act directly on their targets or, in the case of a prodrug approach, require metabolization for their action. Cyclophosphamide (CPA) is a widely used cytostatic drug that requires prodrug activation by cytochrome P450 enzymes (CYP) in the liver. We hypothesize that CPA could induce thrombosis in one of the following ways: (1) damage to endothelial cells (EC) after intra-endothelial metabolization; or (2) direct damage to EC without prior metabolization. In order to investigate this hypothesis, endothelial cells (HUVEC) were treated with CPA in clinically relevant concentrations for up to 8 days. HUVECs were chosen as a model representing the first place of action after intravenous CPA administration. No expression of CYP2B6, CYP3A4, CYP2C9 and CYP2C19 was found in HUVEC, but a weak expression of CYP2C18 was observed. CPA treatment of HUVEC induced DNA damage and a reduced formation of an EC monolayer and caused an increased release of prostacyclin (PGI2) and thromboxane (TXA) associated with a shift of the PGI2/TXA balance to a prothrombotic state. In an in vivo scenario, such processes would promote the risk of thrombus formation. -
PublicationAntimicrobial Polymers of Linear and Bottlebrush Architecture: Probing the Membrane Interaction and Physicochemical Properties( 2022)
;Bapolisi, A.M. ;Kielb, P. ;Bekir, M. ;Lehnen, Anne ;Radon, C. ;Laroque, S. ;Wendler, P. ;Müller-Werkmeister, H.M.Hartlieb, MatthiasPolymeric antimicrobial peptide mimics are a promising alternative for the future management of the daunting problems associated with antimicrobial resistance. However, the development of successful antimicrobial polymers (APs) requires careful control of factors such as amphiphilic balance, molecular weight, dispersity, sequence, and architecture. While most of the earlier developed APs focus on random linear copolymers, the development of APs with advanced architectures proves to be more potent. It is recently developed multivalent bottlebrush APs with improved antibacterial and hemocompatibility profiles, outperforming their linear counterparts. Understanding the rationale behind the outstanding biological activity of these newly developed antimicrobials is vital to further improving their performance. This work investigates the physicochemical properties governing the differences in activity between linear and bottlebrush architectures using various spectroscopic and microscopic techniques. Linear copolymers are more solvated, thermo-responsive, and possess facial amphiphilicity resulting in random aggregations when interacting with liposomes mimicking Escheria coli membranes. The bottlebrush copolymers adopt a more stable secondary conformation in aqueous solution in comparison to linear copolymers, conferring rapid and more specific binding mechanism to membranes. The advantageous physicochemical properties of the bottlebrush topology seem to be a determinant factor in the activity of these promising APs. -
PublicationAssessing Cellular Uptake of Exogenous Coenzyme Q10 into Human Skin Cells by X-ray Fluorescence Imaging( 2022)
;Staufer, Theresa ;Schulze, Mirja L. ;Schmutzler, Oliver ;Körnig, Christian ;Welge, Vivienne ;Burkhardt, Thorsten ;Vietzke, Jens Peter ;Vogelsang, Alexandra ;Weise, Julia Maxi ;Blatt, Thomas ;Dabrowski, Oliver ;Falkenberg, Gerald ;Brückner, Dennis ;Sánchez-Cano, CarlosGrüner, Florian J.J.X-ray fluorescence (XRF) imaging is a highly sensitive non-invasive imaging method for detection of small element quantities in objects, from human-sized scales down to single-cell organelles, using various X-ray beam sizes. Our aim was to investigate the cellular uptake and distribution of Q10, a highly conserved coenzyme with antioxidant and bioenergetic properties. Q10 was labeled with iodine (I2-Q10) and individual primary human skin cells were scanned with nano-focused beams. Distribution of I2-Q10 molecules taken up inside the screened individual skin cells was measured, with a clear correlation between individual Q10 uptake and cell size. Experiments revealed that labeling Q10 with iodine causes no artificial side effects as a result of the labeling procedure itself, and thus is a perfect means of investigating bioavailability and distribution of Q10 in cells. In summary, individual cellular Q10 uptake was demonstrated by XRF, opening the path towards Q10 multi-scale tracking for biodistribution studies. -
PublicationBlue cadmium-free and air-fabricated quantum dot light-emitting diodes( 2023)
;Hänsch, Paul ;Solak, Selen ;Ligorio, Giovanni ;Kim, Jiyong ;List-Kratochvil, Emil J.W.Hermerschmidt, FelixQuantum dot (QD) materials have found increasing use in display applications because of their high color purity and fluorescence quantum yield, enabling devices with higher brightness and efficiency. However, to access large-area printing and coating methods that are carried out in ambient conditions, it is necessary to, first, move away from toxic cadmium, and second, to target materials that can be air-processed. Herein, we synthesize zinc selenide-based blue QD material and air-fabricate light-emitting diodes (LEDs) and single-carrier devices. The encapsulated devices were also measured under ambient conditions. Multi-shell-structured ZnSeTe/ZnSe/ZnS (core/shell/shell) QDs show pure deep blue/purple fluorescence emission with a high photoluminescence quantum yield of 78%. The blue QD-LED devices are fabricated in a conventional structure with bottom light emission with two electron transport materials (ZnO and ZnMgO). The QD-LED devices with ZnO electron transport layer show a maximum luminance of ∼6200 cd m-2 at 9 V with a turn-on voltage of 3.5 V and current efficacy of 0.38 cd A-1, while with ZnMgO electron transport layer, the devices show a maximum luminance of 3000 cd m-2 at 7 V with a turn-on voltage of 3 V and current efficacy of 0.6 cd A-1. Electron-only and hole-only devices were fabricated to show and confirm the underlying charge transport mechanisms. To our knowledge, these results show for the first-time air-fabricated ZnSe-based QD-LEDs, paving the way for scaling up display applications and moving toward high-performance printed electronics. -
PublicationBottlebrush copolymers for gene delivery: Influence of architecture, charge density, and backbone length on transfection efficiency( 2022)
;Floyd, T.G. ;Song, J.I. ;Hapeshi, A. ;Laroque, S. ;Hartlieb, MatthiasPerrier, S.The influence of polymer architecture of polycations on their ability to transfect mammalian cells is probed. Polymer bottle brushes with grafts made from partially hydrolysed poly(2-ethyl-2-oxazoline) are used while varying the length of the polymer backbone as well as the degree of hydrolysis (cationic charge content). Polyplex formation is investigated via gel electrophoresis, dye-displacement and dynamic light scattering. Bottle brushes show a superior ability to complex pDNA when compared to linear copolymers. Also, nucleic acid release was found to be improved by a graft architecture. Polyplexes based on bottle brush copolymers showed an elongated shape in transmission electron microscopy images. The cytotoxicity against mammalian cells is drastically reduced when a graft architecture is used instead of linear copolymers. Moreover, the best-performing bottle brush copolymer showed a transfection ability comparable with that of linear poly(ethylenimine), the gold standard of polymeric transfection agents, which is used as positive control. In combination with their markedly lowered cytotoxicity, cationic bottle brush copolymers are therefore shown to be a highly promising class of gene delivery vectors. -
PublicationCarboxymethyl Chitosan-Functionalized Polyaniline/Polyacrylonitrile Nano-Fibers for Neural Differentiation of Mesenchymal Stem Cells( 2023)
;Arbab Solimani, Sahar ;Irani, Shiva ;Mohamadali, MarjanElectroconductive scaffolds based on polyaniline (PANi)/polyacrylonitrile (PAN) were fabricated and surface-functionalized by carboxymethyl chitosan (CMC) as efficient scaffolds for nerve tissue regeneration. The results of scanning electron microscopy (SEM), Fourier-transform infrared (FTIR) spectroscopy, and water contact angle measurement approved the successful fabrication of CMC-functionalized PANi/PAN-based scaffolds. Human adipose-derived mesenchymal stem cells (hADMSCs) were cultured on the scaffolds for 10 d in the presence or absence of β-carotene (βC, 20 µM) as a natural neural differentiation agent. The MTT and SEM results confirmed the attachment and proliferation of hADMSCs on the scaffolds. The expression of MAP2 at the mRNA and protein levels showed the synergic neurogenic induction effect of CMC-functionalization and βC for hADMSCs on the scaffolds. The CMC-functionalized nanofibrous PANi/PAN-based scaffolds are potential candidates for nerve tissue engineering. -
PublicationChemical Immobilization of Carboxymethyl Chitosan on Polycaprolactone Nanofibers as Osteochondral Scaffolds( 2023)
;Kabirkoohian, A. ;Irani, S.Sharifi, F.Carboxymethyl chitosan (CMC) as a bio-based osteochondral inductive material was chemically immobilized on the surface of polycaprolactone (PCL) nanofibers to fabricate scaffolds for osteochondral tissue engineering applications. The chemical immobilization process included the aminolysis of ester bonds and bonding of the primary amines with glutaraldehyde as a coupling agent. The SEM and FTIR results confirmed the successfulness of the CMC immobilization. The fabricated scaffolds presented cell viabilities of > 82% and supported the attachment and proliferation of the human bone marrow mesenchymal stem cells (hBM-MSCs). The CMC-immobilized scaffolds concentration dependently induced the diverse osteochondral differentiation pathways for the hBM-MSCs without using any external differential agents. According to the Alcian Blue and Alizarin Red staining and immunocytochemistry results, scaffolds with a higher content of CMC presented more chondro-inductivity and less osteoinductivity. Thus, the CMC-immobilized scaffolds can be employed as great potential candidates for osteochondral tissue engineering applications. -
PublicationCombination of 2-tert-Butyl-1,4-Benzoquinone (TBQ) and ZnO Nanoparticles, a New Strategy To Inhibit Biofilm Formation and Virulence Factors of Chromobacterium violaceum( 2023)
;Liu, Junsheng ;Chang, Zengyan ;Chang, Xiaosa ;Li, JunjianJia, AiqunDrug-resistant bacteria have been raising serious social problems. Bacterial biofilms and different virulence factors are the main reasons for persistent infections. As a conditioned pathogen, Chromobacterium violaceum has evolved a vast network of regulatory mechanisms to modify and fine-tune biofilm development, contributing to multidrug resistance. However, there are few therapies to combat drug-resistant bacteria. Quorum sensing (QS) inhibitors (QSIs) are a promising strategy to solve antibiotic resistance. Our previous work suggested that 2-tert-butyl-1,4-benzoquinone (TBQ) is a potent QSI. In this study, the combination of zinc oxide nanoparticles (ZnO-NPs) and TBQ (ZnO-TBQ) was investigated for the treatment of Chromobacterium violaceum ATCC 12472 infection. ZnO-NPs attach to cell walls or biofilms, and the local dissolution of ZnO-NPs can lead to increased Zn21 concentrations, which could destroy metal homeostasis, corresponding to disturbances in amino acid metabolism and nucleic acid metabolism. ZnO-NPs significantly improved the efficiency of TBQ in inhibiting the QS-related virulence factors and biofilm formation of C. violaceum ATCC 12472. ZnO-TBQ effectively reduces the expression of genes related to QS, which is conducive to limiting the infectivity of C. violaceum ATCC 12472. Caenorhabditis elegans nematodes treated with ZnO-TBQ presented a significant improvement in the survival rate by 46.7%. Overall, the combination of ZnO-NPs and TBQ offers a new strategy to attenuate virulence factors and biofilm formation synergistically in some drug-resistant bacteria. IMPORTANCE The combination of ZnO-NPs and TBQ (ZnO-TBQ) can compete with the inducer N-decanoyl-homoserine lactone (C10-HSL) by binding to CviR and down-regulate genes related to the CviI/CviR system to interrupt the QS system of C. violaceum ATCC 12472. The downstream genes responding to cviR were also downregulated so that virulence factors and biofilm formation were inhibited. Furthermore, ZnO-TBQ presents multiple metabolic disturbances in C. violaceum ATCC 12472, which results in the reduced multidrug resistance and pathogenicity of C. violaceum ATCC 12472. In an in vivo assay, C. elegans nematodes treated with ZnO-TBQ presented a significant improvement in the survival rate by 46.7% by limiting the infectivity of C. violaceum ATCC 12472. In addition, ZnO-TBQ inhibited the generation of virulence factors and biofilm formation 2-fold compared to either ZnO-NPs or TBQ alone. The combination of ZnO-NPs with TBQ offers a potent synergistic strategy to reduce multidrug resistance and pathogenicity. -
PublicationCorrection to: Quantitative considerations about the size dependency for cellular entry and excretion of colloidal nanoparticles for different cell types (ChemTexts, (2022), 8, 1, (9), 10.1007/s40828-021-00159-6)( 2022)
;Kang, Y. ;Nack, L. ;Liu, Y. ;Qi, B. ;Huang, Y. ;Liu, Z. ;Chakraborty, I. ;Schulz, F. ;Ahmed, A. ;Clavo Poveda, Mirco ;Hafizi, Fereshta ;Roy, Sathi ;Mutas, Marina ;Cano, C.S. ;Wegner, K.D.Parak, W.J.We regret to inform that the labels "NPs which remain in endosomes/lysosomes" and "exocytosed NPs" had been erroneously swapped in the sketch on the right side in Figure 2. The corrected Fig. 2 is displayed below. WJP apologizes for this error. -
PublicationDevelopment of Topical Formulations with Antibacterial Efficacy from Peel Extract of Mangifera indica: Emulsions and Micro-emulsions( 2022)
;Sriamornsak, Pornsak ;Polat, Arzu ;Torabi, Bighan ;Krongrawa, Wantanwa ;Seidler, TassiloKumpugdee-Vollrath, MontBecause some pathogenic bacteria are becoming more resistant to known antibiotics, more research into the development of new antibacterial agents is required. The main study objective was to develop several formulations containing peel extract of Mangifera indica (mango) and evaluate their antibacterial efficacy. The macerating extraction process was used to produce the mango peel extract. Cytotoxicity of the mango peel extract was also evaluated. The emulsions and microemulsions were prepared and assessed based on their appearance, phase separation, consistency, viscosity, and conductivity. The formulations were then evaluated for antibacterial and growth inhibitory effects against gram-negative (Escherichia coli) and gram-positive (Staphylococcus aureus) bacteria. The findings revealed that no cytotoxic effects on skin keratinocyte cells were identified. Most formulations were physico-chemically acceptable. Only S. aureus bacteria were inhibited by emulsions and microemulsions containing mango peel extract. -
PublicationEnabling X-ray fluorescence imaging for in vivo immune cell tracking( 2023)
;Staufer, Theresa ;Körnig, Christian ;Liu, Beibei ;Liu, Yang ;Lanzloth, Clarissa ;Schmutzler, Oliver ;Bedke, Tanja ;Machicote, Andres ;Parak, Wolfgang J. ;Bosurgi, Lidia ;Huber, SamuelGrüner, FlorianThe infiltration of immune cells into sites of inflammation is one key feature of immune mediated inflammatory diseases. A detailed assessment of the in vivo dynamics of relevant cell subtypes could booster the understanding of this disease and the development of novel therapies. We show in detail how advanced X-ray fluorescence imaging enables such quantitative in vivo cell tracking, offering solutions that could pave the way beyond what other imaging modalities provide today. The key for this achievement is a detailed study of the spectral background contribution from multiple Compton scattering in a mouse-scaled object when this is scanned with a monochromatic pencil X-ray beam from a synchrotron. Under optimal conditions, the detection sensitivity is sufficient for detecting local accumulations of the labelled immune cells, hence providing experimental demonstration of in vivo immune cell tracking in mice. -
PublicationEnhanced Electroluminescence via a Nanohybrid Material Consisting of Aromatic Ligand-Modified InP Quantum Dots and an Electron-Blocking Polymer as the Single Active Layer in Quantum Dot-LEDs( 2022)
;Roddatis, V. ;Kim, JiyongElectron overcharge causes rapid luminescence quenching in the quantum dot (QD) emission layer in QD light-emitting diodes (QD-LEDs), resulting in low device performance. In this paper we describe the application of different aromatic thiol ligands and their influence on device performance as well as their behavior in combination with an electron blocking material (EBM). The three different ligands, 1-octanethiol (OcSH), thiophenol (TP), and phenylbutan-1-thiol (PBSH), were introduced on to InP/ZnSe/ZnS QDs referred to as QD-OcSH, QD-TP, and QD-PBSH. PBSH is in particular applied as a ligand to improve QD solubility and to enhance the charge transport properties synergistically with EBM probably via π-π interaction. We synthesized poly-[N,N-bis[4-(carbazolyl)phenyl]-4-vinylaniline] (PBCTA) and utilized it as an EBM to alleviate excess electrons in the active layer in QD-LEDs. The comparison of the three QD systems in an inverted device structure without the application of PBCTA as an EBM shows the highest efficiency for QD–PBSH. Moreover, when PBCTA is introduced as an EBM in the active layer in combination with QD-PBSH in a conventional device structure, the current efficiency shows a twofold increase compared to the reference device without EBM. These results strongly confirm the role of PBCTA as an EBM that effectively alleviates excess electrons in the active layer, leading to higher device efficiency. -
PublicationErratum to: Cold Atmosphere Plasma Modification on Beta-Carotene-Loaded Nanofibers to Enhance Osteogenic Differentiation (Fibers and Polymers, (2022), 23, 1, (18-27), 10.1007/s12221-021-0033-y)( 2022)
;Moradi, Yasamin ;Atyabi, Seyed Alireza ;Ghiassadin, Ali ;Irani, Shiva ;Atyabi, Seyed MohammadDadgar, NedaThe article Cold Atmosphere Plasma Modification on Beta-Carotene-Loaded Nanofibers to Enhance Osteogenic Differentiation, written by Yasamin Moradi, Seyed Alireza Atyabi, Ali Ghiassadin, Hadi Bakhshi, Shiva Irani, Seyed Mohammad Atyabi, and Neda Dadgar, was mistakenly originally published without open access. After publication in Vol.23, No.1, page 18–27 this was corrected and the article was made an open access publication. Therefore, the copyright of the article has been changed to and the article is forthwith distributed under the terms of the Creative Commons Attribution 4.0 International License (https://doi.org/10.1007/s12221-021-0033-y), which permits use, duplication, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The original article has been corrected. -
PublicationFabrication of Eco-Friendly Wearable Strain Sensor Arrays via Facile Contact Printing for Healthcare Applications( 2023)
;Wu, Shin-Da ;Hsu, Shan-hui ;Ketelsen, Bendix ;Bittinger, Sophia C.Voßmeyer, TobiasWearable flexible strain sensors with spatial resolution enable the acquisition and analysis of complex actions for noninvasive personalized healthcare applications. To provide secure contact with skin and to avoid environmental pollution after usage, sensors with biocompatibility and biodegradability are highly desirable. Herein, wearable flexible strain sensors composed of crosslinked gold nanoparticle (GNP) thin films as the active conductive layer and transparent biodegradable polyurethane (PU) films as the flexible substrate are developed. The patterned GNP films (micrometer- to millimeter-scale square and rectangle geometry, alphabetic characters, and wave and array patterns) are transferred onto the biodegradable PU film via a facile, clean, rapid and high-precision contact printing method, without the need of a sacrificial polymer carrier or organic solvents. The GNP-PU strain sensor with low Young's modulus (≈17.8 MPa) and high stretchability showed good stability and durability (10 000 cycles) as well as degradability (42% weight loss after 17 days at 74 °C in water). The GNP-PU strain sensor arrays with spatiotemporal strain resolution are applied as wearable eco-friendly electronics for monitoring subtle physiological signals (e.g., mapping of arterial lines and sensing pulse waveforms) and large-strain actions (e.g., finger bending). -
PublicationFabrication of Patchy Silica Microspheres with Tailor-Made Patch Functionality using Photo-Iniferter Reversible-Addition-Fragmentation Chain-Transfer (PI-RAFT) Polymerization( 2023)
;Akarsu, Pinar ;Lehnen, Anne ;Bekir, Marek ;Hartlieb, MatthiasTheir inherent directional information renders patchy particles interesting building blocks for advanced applications in materials science. In this study, a feasible method to fabricate patchy silicon dioxide microspheres is demonstrated, which they are able to equip with tailor-made polymeric materials as patches. Their fabrication method relies on a solid-state supported microcontact printing (µCP) routine optimized for the transfer of functional groups to capillary-active substrates, which is used to introduce amino functionalities as patches to a monolayer of particles. Acting as anchor groups for polymerization, photo-iniferter reversible addition-fragmentation chain-transfer (RAFT) is used to graft polymer from the patch areas. Accordingly, particles with poly(N-acryloyl morpholine), poly(N-isopropyl acrylamide), and poly(n-butyl acrylate) are prepared as representative acrylic acid-derived functional patch materials. To facilitate their handling in water, a passivation strategy of the particles for aqueous systems is introduced. The protocol introduced here, therefore, promises a vast degree of freedom in engineering the surface properties of highly functional patchy particles. This feature is unmatched by other techniques to fabricate anisotropic colloids. The method, thus, can be considered a platform technology, culminating in the fabrication of particles that possess locally precisely formed patches on particles at a low µm scale with a high material functionality. -
PublicationFormulation of Microemulsions Containing Rambutan Peel Extract and Their Antibacterial Activities( 2023)
;Sriamornsak, Pornsak ;Polat, Arzu ;Krongrawa, Wantanwa ;Seidler, TassiloKumpugdee-Vollrath, MontNowadays, numerous pathogens have become increasingly resistant to antibiotics. To address this issue, it is important to undertake additional research to develop alternative antibacterial agents. The goal of this investigation was to fabricate microemulsions from rambutan (Nephelium lappaceum L.) peel extract and test their antibacterial activity. The cytotoxicity of the rambutan peel extract was studied. The other assessments were conducted on the visual, physical, and electrical properties of microemulsions, which include their appearance, phase separation, viscosity, and conductivity. Moreover, the research also examined the potential antibacterial effects of microemulsions against both gram-negative (Escherichia coli) and gram-positive (Staphylococcus aureus) bacteria by exploring their ability to inhibit bacterial growth. The findings indicated that even when the extract was used at the highest concentration (100 µg/mL), there were no cytotoxic effects on skin keratinocyte cells. Using the pseudoternary phase diagram, a blend of rosemary oil, water, and a combination of surfactant (Tween® 80) and co-surfactant (Ethanol) were employed to create microemulsions containing different quantities of rambutan peel extract. According to the results, a stable microemulsion was observed as the ratio of Tween® 80 and ethanol was higher than 38%. The microemulsions containing extract at concentrations of 1% w/w, 5% w/w, and 10% w/w were clear and transparent, with no phase separation. All formulations were physiochemically acceptable. Microemulsions containing 1% w/w – 10% w/w rambutan peel extracts were shown to be efficient in suppressing only gram-positive S. aureus.