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Start date: 1999 × Type: Text × Subject: Biocompatibility × WGL Institute: IPF ×

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Now showing 1 - 7 of 7
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    A “built-up” composite film with synergistic functionalities on Mg–2Zn–1Mn bioresorbable stents improves corrosion control effects and biocompatibility
    ([Bejing] : KeAi Publishing, 2023) Dou, Zhenglong; Chen, Shuiling; Wang, Jiacheng; Xia, Li; Maitz, Manfred F.; Tu, Qiufen; Zhang, Wentai; Yang, Zhilu; Huang, Nan
    Control of premature corrosion of magnesium (Mg) alloy bioresorbable stents (BRS) is frequently achieved by the addition of rare earth elements. However, limited long-term experience with these elements causes concerns for clinical application and alternative methods of corrosion control are sought after. Herein, we report a “built-up” composite film consisting of a bottom layer of MgF2 conversion coating, a sandwich layer of a poly (1, 3-trimethylene carbonate) (PTMC) and 3-aminopropyl triethoxysilane (APTES) co-spray coating (PA) and on top a layer of poly (lactic-co-glycolic acid) (PLGA) ultrasonic spray coating to decorate the rare earth element-free Mg–2Zn–1Mn (ZM21) BRS for tailoring both corrosion resistance and biological functions. The developed “built-up” composite film shows synergistic functionalities, allowing the compression and expansion of the coated ZM21 BRS on an angioplasty balloon without cracking or peeling. Of special importance is that the synergistic corrosion control effects of the “built-up” composite film allow for maintaining the mechanical integrity of stents for up to 3 months, where complete biodegradation and no foreign matter residue were observed about half a year after implantation in rabbit iliac arteries. Moreover, the functionalized ZM21 BRS accomplished re-endothelialization within one month.
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    A non-cytotoxic resin for micro-stereolithography for cell cultures of HUVECs
    (Basel : MDPI, 2020) Männel, Max J.; Fischer, Carolin; Thiele, Julian
    Three-dimensional (3D) printing of microfluidic devices continuously replaces conventional fabrication methods. A versatile tool for achieving microscopic feature sizes and short process times is micro-stereolithography (µSL). However, common resins for µSL lack biocompatibility and are cytotoxic. This work focuses on developing new photo-curable resins as a basis for µSL fabrication of polymer materials and surfaces for cell culture. Different acrylate-and methacrylate-based compositions are screened for material characteristics including wettability, surface roughness, and swelling behavior. For further understanding, the impact of photo-absorber and photo-initiator on the cytotoxicity of 3D-printed substrates is studied. Cell culture experiments with human umbilical vein endothelial cells (HUVECs) in standard polystyrene vessels are compared to 3D-printed parts made from our library of homemade resins. Among these, after optimizing material composition and post-processing, we identify selected mixtures of poly(ethylene glycol) diacrylate (PEGDA) and poly(ethylene glycol) methyl ethyl methacrylate (PEGMEMA) as most suitable to allow for fabricating cell culture platforms that retain both the viability and proliferation of HUVECs. Next, our PEGDA/PEGMEMA resins will be further optimized regarding minimal feature size and cell adhesion to fabricate microscopic (microfluidic) cell culture platforms, e.g., for studying vascularization of HUVECs in vitro. © 2020 by the authors.
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    Poly(propylene imine) dendrimers with histidine-maltose shell as novel type of nanoparticles for synapse and memory protection
    (Basel : MDPI, 2019) Aso, Ester; Martinsson, Isak; Appelhans, Dietmar; Effenberg, Christiane; Benseny-Cases, Nuria; Cladera, Josep; Gouras, Gunnar; Ferrer, Isidre; Klementieva, Oxana
    Poly(propylene imine) dendrimers have been shown to be promising 3-dimensional polymers for the use in the pharmaceutical and biomedical applications. Our aims of this study were first, to synthesize a novel type of dendrimer with poly(propylene imine) core and maltose-histidine shell (G4HisMal) assessing if maltose-histidine shell can improve the biocompatibility and the ability to cross the blood-brain barrier, and second, to investigate the potential of G4HisMal to protect Alzheimer disease transgenic mice from memory impairment. Our data demonstrate that G4HisMal has significantly improved biocompatibility and ability to cross the blood-brain barrier in vivo. Therefore, we suggest that a maltose-histidine shell can be used to improve biocompatibility and ability to cross the blood-brain barrier of dendrimers. Moreover, G4HisMal demonstrated properties for synapse and memory protection when administered to Alzheimer disease transgenic mice. Therefore, G4HisMal can be considered as a promising drug candidate to prevent Alzheimer disease via synapse protection. © 2019 The Authors
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    Systematic evaluation of oligodeoxynucleotide binding and hybridization to modified multi-walled carbon nanotubes
    (London : Biomed Central, 2017) Kaufmann, Anika; Hampel, Silke; Rieger, Christiane; Kunhardt, David; Schendel, Darja; Füssel, Susanne; Schwenzer, Bernd; Erdmann, Kati
    Background: In addition to conventional chemotherapeutics, nucleic acid-based therapeutics like antisense oligodeoxynucleotides (AS-ODN) represent a novel approach for the treatment of bladder cancer (BCa). An efficient delivery of AS-ODN to the urothelium and then into cancer cells might be achieved by the local application of multi-walled carbon nanotubes (MWCNT). In the present study, pristine MWCNT and MWCNT functionalized with hydrophilic moieties were synthesized and then investigated regarding their physicochemical characteristics, dispersibility, biocompatibility, cellular uptake and mucoadhesive properties. Finally, their binding capacity for AS-ODN via hybridization to carrier strand oligodeoxynucleotides (CS-ODN), which were either non-covalently adsorbed or covalently bound to the different MWCNT types, was evaluated. Results: Pristine MWCNT were successfully functionalized with hydrophilic moieties (MWCNT-OH, -COOH, -NH2, -SH), which led to an improved dispersibility and an enhanced dispersion stability. A viability assay revealed that MWCNT-OH, MWCNT-NH2 and MWCNT-SH were most biocompatible. All MWCNT were internalized by BCa cells, whereupon the highest uptake was observed for MWCNT-OH with 40% of the cells showing an engulfment. Furthermore, all types of MWCNT could adhere to the urothelium of explanted mouse bladders, but the amount of the covered urothelial area was with 2-7% rather low. As indicated by fluorescence measurements, it was possible to attach CS-ODN by adsorption and covalent binding to functionalized MWCNT. Adsorption of CS-ODN to pristine MWCNT, MWCNT-COOH and MWCNT-NH2 as well as covalent coupling to MWCNT-NH2 and MWCNT-SH resulted in the best binding capacity and stability. Subsequently, therapeutic AS-ODN could be hybridized to and reversibly released from the CS-ODN coupled via both strategies to the functionalized MWCNT. The release of AS-ODN at experimental conditions (80 °C, buffer) was most effective from CS-ODN adsorbed to MWCNT-OH and MWCNT-NH2 as well as from CS-ODN covalently attached to MWCNT-COOH, MWCNT-NH2 and MWCNT-SH. Furthermore, we could exemplarily demonstrate that AS-ODN could be released following hybridization to CS-ODN adsorbed to MWCNT-OH at physiological settings (37 °C, urine). Conclusions: In conclusion, functionalized MWCNT might be used as nanotransporters in antisense therapy for the local treatment of BCa.
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    Interaction between immobilized polyelectrolyte complex nanoparticles and human mesenchymal stromal cells
    (Auckland : DOVE Medical Press, 2014) Woltmann, B.; Torger, B.; Müller, M.; Hempel, U.
    Background: Implant loosening or deficient osseointegration is a major problem in patients with systemic bone diseases (eg, osteoporosis). For this reason, the stimulation of the regional cell population by local and sustained drug delivery at the bone/implant interface to induce the formation of a mechanical stable bone is promising. The purpose of this study was to investigate the interaction of polymer-based nanoparticles with human bone marrow-derived cells, considering nanoparticles' composition and surface net charge. Materials and methods: Polyelectrolyte complex nanoparticles (PECNPs) composed of the polycations poly(ethyleneimine) (PEI), poly(L-lysine) (PLL), or (N,N-diethylamino)ethyldextran (DEAE) in combination with the polyanions dextran sulfate (DS) or cellulose sulfate (CS) were prepared. PECNPs' physicochemical properties (size, net charge) were characterized by dynamic light scattering and particle charge detector measurements. Biocompatibility was investigated using human mesenchymal stromal cells (hMSCs) cultured on immobilized PECNP films (5-50 nmol·cm-2) by analysis for metabolic activity of hMSCs in dependence of PECNP surface concentration by MTS (3-[4,5-dimethylthiazol-2-yl]-5-[3-carboxymethoxyphenyl]-2-[4-sulfophenyl]-2H-tetrazolium, inner salt) assay, as well as cell morphology (phase contrast microscopy). Results: PECNPs ranging between ~50 nm and 150 nm were prepared. By varying the ratio of polycations and polyanions, PECNPs with a slightly positive (PEC+NP) or negative (PEC-NP) net charge were obtained. The PECNP composition significantly affected cell morphology and metabolic activity, whereas the net charge had a negligible influence. Therefore, we classified PECNPs into "variant systems" featuring a significant dose dependency of metabolic activity (DEAE/CS, PEI/DS) and "invariant systems" lacking such a dependency (DEAE/DS, PEI/CS). Immunofluorescence imaging of fluorescein isothiocyanate isomer I (FITC)-labeled PECNPs suggested internalization into hMSCs remaining stable for 8 days. Conclusion: Our study demonstrated that PECNP composition affects hMSC behavior. In particular, the PEI/CS system showed biocompatibility in a wide concentration range, representing a suitable system for local drug delivery from PECNP-functionalized bone substitute materials.
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    Deepening the insight into poly(butylene oxide)-block-poly(glycidol) synthesis and self-assemblies: micelles, worms and vesicles
    (Cambridge : RSC, 2020) Wehr, Riccardo; Gaitzsch, Jens; Daubian, Davy; Fodor, Csaba; Meier, Wolfgang
    Aqueous self-assembly of amphiphilic block copolymers is studied extensively for biomedical applications like drug delivery and nanoreactors. The commonly used hydrophilic block poly(ethylene oxide) (PEO), however, suffers from several drawbacks. As a potent alternative, poly(glycidol) (PG) has gained increasing interest, benefiting from its easy synthesis, high biocompatibility and flexibility as well as enhanced functionality compared to PEO. In this study, we present a quick and well-controlled synthesis of poly(butylene oxide)-block-poly(glycidol) (PBO-b-PG) amphiphilic diblock copolymers together with a straight-forward self-assembly protocol. Depending on the hydrophilic mass fraction of the copolymer, nanoscopic micelles, worms and polymersomes were formed as well as microscopic giant unilamellar vesicles. The particles were analysed regarding their size and shape, using dynamic and static light scattering, TEM and Cryo-TEM imaging as well as confocal laser scanning microscopy. We have discovered a strong dependence of the formed morphology on the self-assembly method and show that only solvent exchange leads to the formation of homogenous phases. Thus, a variety of different structures can be obtained from a highly flexible copolymer, justifying a potential use in biomedical applications. This journal is © The Royal Society of Chemistry.
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    A novel patch micro electrode array for sensing ionic membrane currents
    (Amsterdam [u.a.] : Elsevier, 2011) Aryasomayajula, A.; Perike, S.; Hensel, R.; Posseckardt, J.; Gerlach, G.; Funk, R.H.W.
    Ionic membrane currents play an important role during regeneration of nerve cells, embryonic development and wound healing processes. Measuring the intracellular ion currents across the cell membrane is important in understanding the cellular functions related to the ion activities. A novel patch micro electrode array (p-MEA) for measuring the ionic membrane currents without poisoning the cells due to emitting metal ions is described in this paper. Results on biocompatibility of the device are presented. We discuss the fabrication and working principle of p-MEA.