2020, Nittala, Aditya Shekhar, Khan, Arshad, Kruttwig, Klaus, Kraus, Tobias, Steimle, Jürgen, Bernhaupt, Regina

Advances in rapid prototyping platforms have made physiological sensing accessible to a wide audience. However, off-the-shelf electrodes commonly used for capturing biosignals are typically thick, non-conformal and do not support customization. We present PhysioSkin, a rapid, do-it-yourself prototyping method for fabricating custom multi-modal physiological sensors, using commercial materials and a commodity desktop inkjet printer. It realizes ultrathin skin-conformal patches (~1μm) and interactive textiles that capture sEMG, EDA and ECG signals. It further supports fabricating devices with custom levels of thickness and stretchability. We present detailed fabrication explorations on multiple substrate materials, functional inks and skin adhesive materials. Informed from the literature, we also provide design recommendations for each of the modalities. Evaluation results show that the sensor patches achieve a high signal-to-noise ratio. Example applications demonstrate the functionality and versatility of our approach for prototyping a next generation of physiological devices that intimately couple with the human body.

2021, Trenkenschuh, Eduard, Richter, Maximilian, Heinrich, Eilien, Koch, Marcus, Fuhrmann, Gregor, Friess, Wolfgang

Extracellular vesicles (EV) are an emerging technology as immune therapeutics and drug delivery vehicles. However, EVs are usually stored at −80 °C which limits potential clinical applicability. Freeze-drying of EVs striving for long-term stable formulations is therefore studied. The most appropriate formulation parameters are identified in freeze-thawing studies with two different EV types. After a freeze-drying feasibility study, four lyophilized EV formulations are tested for storage stability for up to 6 months. Freeze-thawing studies revealed improved colloidal EV stability in presence of sucrose or potassium phosphate buffer instead of sodium phosphate buffer or phosphate-buffered saline. Less aggregation and/or vesicle fusion occurred at neutral pH compared to slightly acidic or alkaline pH. EVs colloidal stability can be most effectively preserved by addition of low amounts of poloxamer 188. Polyvinyl pyrrolidone failed to preserve EVs upon freeze-drying. Particle size and concentration of EVs are retained over 6 months at 40 °C in lyophilizates containing 10 mm K- or Na-phosphate buffer, 0.02% poloxamer 188, and 5% sucrose. The biological activity of associated beta-glucuronidase is maintained for 1 month, but decreased after 6 months. Here optimized parameters for lyophilization of EVs that contribute to generate long-term stable EV formulations are presented. © 2021 The Authors. Advanced Healthcare Materials published by Wiley-VCH GmbH

2021, Richter, Robert, Kamal, Mohamed A.M., Koch, Marcus, Niebuur, Bart-Jan, Huber, Anna-Lena, Goes, Adriely, Volz, Carsten, Vergalli, Julia, Kraus, Tobias, Müller, Rolf, Schneider-Daum, Nicole, Fuhrmann, Gregor, Pagès, Jean-Marie, Lehr, Claus-Michael

When searching for new antibiotics against Gram-negative bacterial infections, a better understanding of the permeability across the cell envelope and tools to discriminate high from low bacterial bioavailability compounds are urgently needed. Inspired by the phospholipid vesicle-based permeation assay (PVPA), which is designed to predict non-facilitated permeation across phospholipid membranes, outer membrane vesicles (OMVs) of Escherichia coli either enriched or deficient of porins are employed to coat filter supports for predicting drug uptake across the complex cell envelope. OMVs and the obtained in vitro model are structurally and functionally characterized using cryo-TEM, SEM, CLSM, SAXS, and light scattering techniques. In vitro permeability, obtained from the membrane model for a set of nine antibiotics, correlates with reported in bacterio accumulation data and allows to discriminate high from low accumulating antibiotics. In contrast, the correlation of the same data set generated by liposome-based comparator membranes is poor. This better correlation of the OMV-derived membranes points to the importance of hydrophilic membrane components, such as lipopolysaccharides and porins, since those features are lacking in liposomal comparator membranes. This approach can offer in the future a high throughput screening tool with high predictive capacity or can help to identify compound- and bacteria-specific passive uptake pathways.

2022, Alhayek, Alaa, Khan, Essak S., Schönauer, Esther, Däinghaus, Tobias, Shafiei, Roya, Voos, Katrin, Han, Mitchell K. L., Ducho, Christian, Posselt, Gernot, Wessler, Silja, Brandstetter, Hans, Haupenthal, Jörg, Del Campo, Aránzazu, Hirsch, Anna K. H.

Despite the progress in surgical techniques and antibiotic prophylaxis, opportunistic wound infections with Bacillus cereus remain a public health problem. Secreted toxins are one of the main factors contributing to B. cereus pathogenicity. A promising strategy to treat such infections is to target these toxins and not the bacteria. Although the exoenzymes produced by B. cereus are thoroughly investigated, little is known about the role of B. cereus collagenases in wound infections. In this report, the collagenolytic activity of secreted collagenases (Col) is characterized in the B. cereus culture supernatant (csn) and its isolated recombinantly produced ColQ1 is characterized. The data reveals that ColQ1 causes damage on dermal collagen (COL). This results in gaps in the tissue, which might facilitate the spread of bacteria. The importance of B. cereus collagenases is also demonstrated in disease promotion using two inhibitors. Compound 2 shows high efficacy in peptidolytic, gelatinolytic, and COL degradation assays. It also preserves the fibrillar COLs in skin tissue challenged with ColQ1, as well as the viability of skin cells treated with B. cereus csn. A Galleria mellonella model highlights the significance of collagenase inhibition in vivo.

2019, Nittala, Aditya Shekhar, Kruttwig, Klaus, Lee, Jaeyeon, Bennewitz, Roland, Arzt, Eduard, Steimle, Jürgen, Brewster, Stephen

The emerging class of epidermal devices opens up new opportunities for skin-based sensing, computing, and interaction. Future design of these devices requires an understanding of how skin-worn devices affect the natural tactile perception. In this study, we approach this research challenge by proposing a novel classification system for epidermal devices based on flexural rigidity and by testing advanced adhesive materials, including tattoo paper and thin films of poly (dimethylsiloxane) (PDMS). We report on the results of three psychophysical experiments that investigated the effect of epidermal devices of different rigidity on passive and active tactile perception. We analyzed human tactile sensitivity thresholds, two-point discrimination thresholds, and roughness discrimination abilities on three different body locations (fingertip, hand, forearm). Generally, a correlation was found between device rigidity and tactile sensitivity thresholds as well as roughness discrimination ability. Surprisingly, thin epidermal devices based on PDMS with a hundred times the rigidity of commonly used tattoo paper resulted in comparable levels of tactile acuity. The material offers the benefit of increased robustness against wear and the option to re-use the device. Based on our findings, we derive design recommendations for epidermal devices that combine tactile perception with device robustness.

2019, Menina, S., Eisenbeis, J., Kamal, M.A.M., Koch, M., Bischoff, M., Gordon, S., Loretz, B., Lehr, C.-M.

Bacterial invasion into eukaryotic cells and the establishment of intracellular infection has proven to be an effective means of resisting antibiotic action, as anti-infective agents commonly exhibit a poor permeability across the host cell membrane. Encapsulation of anti-infectives into nanoscaled delivery systems, such as liposomes, is shown to result in an enhancement of intracellular delivery. The aim of the current work is, therefore, to formulate colistin, a poorly permeable anti-infective, into liposomes suitable for oral delivery, and to functionalize these carriers with a bacteria-derived invasive moiety to enhance their intracellular delivery. Different combinations of phospholipids and cholesterol are explored to optimize liposomal drug encapsulation and stability in biorelevant media. These liposomes are then surface-functionalized with extracellular adherence protein (Eap), derived from Staphylococcus aureus. Treatment of HEp-2 and Caco-2 cells infected with Salmonella enterica using colistin-containing, Eap-functionalized liposomes resulted in a significant reduction of intracellular bacteria, in comparison to treatment with nonfunctionalized liposomes as well as colistin alone. This indicates that such bio-invasive carriers are able to facilitate intracellular delivery of colistin, as necessary for intracellular anti-infective activity. The developed Eap-functionalized liposomes, therefore, present a promising strategy for improving the therapy of intracellular infections. © 2019 The Authors. Published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

2020, Dumitru, Andra C., Mohammed, Danahe, Maja, Mauriane, Yang, Jinsung, Verstraeten, Sandrine, del Campo, Aranzazu, Mingeot-Leclercq, Marie-Paule, Tyteca, Donatienne, Alsteens, David

Tumor cells present profound alterations in their composition, structural organization, and functional properties. A landmark of cancer cells is an overall altered mechanical phenotype, which so far are linked to changes in their cytoskeletal regulation and organization. Evidence exists that the plasma membrane (PM) of cancer cells also shows drastic changes in its composition and organization. However, biomechanical characterization of PM remains limited mainly due to the difficulties encountered to investigate it in a quantitative and label‐free manner. Here, the biomechanical properties of PM of a series of MCF10 cell lines, used as a model of breast cancer progression, are investigated. Notably, a strong correlation between the cell PM elasticity and oncogenesis is observed. The altered membrane composition under cancer progression, as emphasized by the PM‐associated cholesterol levels, leads to a stiffening of the PM that is uncoupled from the elastic cytoskeletal properties. Conversely, cholesterol depletion of metastatic cells leads to a softening of their PM, restoring biomechanical properties similar to benign cells. As novel therapies based on targeting membrane lipids in cancer cells represent a promising approach in the field of anticancer drug development, this method contributes to deciphering the functional link between PM lipid content and disease.

2021, Nair, Roshna V., Farrukh, Aleeza, del Campo, Aránzazu

The application of growth factor based therapies in regenerative medicine is limited by the high cost, fast degradation kinetics, and the multiple functions of these molecules in the cell, which requires regulated delivery to minimize side effects. Here a photoactivatable peptidomimetic of the vascular endothelial growth factor (VEGF) that allows the light-controlled presentation of angiogenic signals to endothelial cells embedded in hydrogel matrices is presented. A photoresponsive analog of the 15-mer peptidomimetic Ac-KLTWQELYQLKYKGI-NH2 (abbreviated PQK) is prepared by introducing a 3-(4,5-dimethoxy-2-nitrophenyl)-2-butyl (DMNPB) photoremovable protecting group at the Trp4 residue. This modification inhibits the angiogenic potential of the peptide temporally. Light exposure of PQK modified hydrogels provide instructive cues to embedded endothelial cells and promote angiogenesis at the illuminated sites of the 3D culture, with the possibility of spatial control. PQK modified photoresponsive biomaterials offer an attractive approach for the dosed delivery and spatial control of pro-angiogenic factors to support regulated vascular growth by just using light as an external trigger.

2021, Mehanny, Mina, Kroniger, Tobias, Koch, Marcus, Hoppstädter, Jessica, Becher, Dörte, Kiemer, Alexandra K., Lehr, Claus-Michael, Fuhrmann, Gregor

Streptococcus pneumoniae infections are a leading cause of death worldwide. Bacterial membrane vesicles (MVs) are promising vaccine candidates because of the antigenic components of their parent microorganisms. Pneumococcal MVs exhibit low toxicity towards several cell lines, but their clinical translation requires a high yield and strong immunogenic effects without compromising immune cell viability. MVs are isolated during either the stationary phase (24 h) or death phase (48 h), and their yields, immunogenicity and cytotoxicity in human primary macrophages and dendritic cells have been investigated. Death-phase vesicles showed higher yields than stationary-phase vesicles. Both vesicle types displayed acceptable compatibility with primary immune cells and several cell lines. Both vesicle types showed comparable uptake and enhanced release of the inflammatory cytokines, tumor necrosis factor and interleukin-6, from human primary immune cells. Proteomic analysis revealed similarities in vesicular immunogenic proteins such as pneumolysin, pneumococcal surface protein A, and IgA1 protease in both vesicle types, but stationary-phase MVs showed significantly lower autolysin levels than death-phase MVs. Although death-phase vesicles produced higher yields, they lacked superiority to stationary-phase vesicles as vaccine candidates owing to their similar antigenic protein cargo and comparable uptake into primary human immune cells.

2021, Lana, Gabriela Moreira, Sorg, Katharina, Wenzel, Gentiana Ioana, Hecker, Dietmar, Hensel, René, Schick, Bernhard, Kruttwig, Klaus, Arzt, Eduard

Inspired by the gecko foot, polymeric microstructures have demonstrated reliable dry adhesion to both stiff objects and sensitive surfaces such as skin. Microstructured silicone patches are proposed, herein, for the treatment of tympanic membrane perforations with the aim of serving as an alternative for current surgical procedures that require anesthesia and ear canal packing. Sylgard 184 PDMS micropillars of 20 μm in diameter and 60 μm in length are topped by a Soft Skin Adhesive (SSA) MG7-1010 terminal layer, of about 25 μm thickness. The adhesion is evaluated by specially designed tack tests against explanted murine eardrums and, for comparison, against a rigid substrate. Functional effects are evaluated using auditory brainstem responses (ABRs) and distortion product otoacoustic emissions (DPOAE). The adhesion strength of the microstructure and unstructured controls to explanted murine tympanic membranes is comparable (typically 12 kPa), but the microstructured patches are easier to handle by the surgeon. For the first time, partial recovery of hearing performance is measured immediately after patch application. The novel patches adhere without the need for further fixation, removing the need for ear canal packing. The proposed material design holds great promise for improving clinical treatments of tympanic membrane perforations.