In Situ 3D-Printing using a Bio-ink of Protein-photosensitizer Conjugates for Single-cell Manipulation.

Living tissues dynamically modulate their structure and functions through physical and biochemical interactions in the three-dimensional (3D)-microenvironment for their homeostasis or the developmental process of an embryo. However, the manipulation of cellular functions in vitro is still challenging due to the lack of a dynamic material system that can vary the 3D-cellular microenvironment in time and space. Here, we show an in situ 3D-printing technique based on multiphoton lithography using a biocompatible photoresist, bio-ink. The bio-ink composed of protein-photosensitizer conjugates has the ability to cause singlet oxygen and cross-linking reaction to fabricate protein gels with submicrometer-scale precision. Remarkably, the conjugates substantially improve the cytocompatibility and the efficiency of gelation due to the stealth effect of rose bengal (RB) and efficient transfer of singlet oxygen to bovine serum albumin (BSA). 3D-printing in the presence of cells allows for the microfabrication of a protein scaffold and controlled single-cell behavior. This dynamic material system to direct cell fate may offer emerging applications for drug discovery and regenerative medicine.

3D-Printing of Structure-Controlled Antigen Nanoparticles for Vaccine Delivery.

Targeted delivery of antigens to immune cells using micro/nanocarriers may serve as a therapeutic application for vaccination. However, synthetic carriers have potential drawbacks including cytotoxicity, low encapsulation efficiency of antigen, and lack of a morphological design, which limit the translation of the delivery system to clinical use. Here, we report a carrier-free and three-dimensional (3D)-shape-designed antigen nanoparticle by multiphoton lithography-based 3D-printing. This simple, versatile 3D-printing approach provides freedom for the precise design of particle shapes with a nanoscale resolution. Importantly, shape-designed antigen nanoparticles with distinct aspect ratios show shape-dependent immune responses. The 3D-printing approach for the rational design of nanomaterials with increasing safety, complexity, and efficacy offers an emerging platform to develop vaccine delivery systems and mechanistic understanding.

Long-Term and Clinically Relevant Full-Thickness Human Skin Equivalent for Psoriasis.

Psoriasis is an incurable, immune-mediated inflammatory disease characterized by the hyperproliferation and abnormal differentiation of keratinocytes. To study in depth the pathogenesis of this disease and possible therapy options suitable, pre-clinical models are required. Three-dimensional skin equivalents are a potential alternative to simplistic monolayer cultures and immunologically different animal models. However, current skin equivalents lack long-term stability, which jeopardizes the possibility to simulate the complex disease-specific phenotype followed by long-term therapeutic treatment. To overcome this limitation, the cell coating technique was used to fabricate full-thickness human skin equivalents (HSEs). This rapid and scaffold-free fabrication method relies on coating cell membranes with nanofilms using layer-by-layer assembly, thereby allowing extended cultivation of HSEs up to 49 days. The advantage in time is exploited to develop a model that not only forms a disease phenotype but can also be used to monitor the effects of topical or systemic treatment. To generate a psoriatic phenotype, the HSEs were stimulated with recombinant human interleukin 17A (rhIL-17A). This was followed by systemic treatment of the HSEs with the anti-IL-17A antibody secukinumab in the presence of rhIL-17A. Microarray and RT-PCR analysis demonstrated that HSEs treated with rhIL-17A showed downregulation of differentiation markers and upregulation of chemokines and cytokines, while treatment with anti-IL-17A antibody reverted these gene regulations. Gene ontology analysis revealed the proinflammatory and chemotactic effects of rhIL-17A on the established HSEs. These data demonstrated, at the molecular level, the effects of anti-IL-17A antibody on rhIL-17A-induced gene regulations. This shows the physiological relevance of the developed HSE and opens venues for its use as an alternative to ex vivo skin explants and animal testing.

The swimming of a deforming helix.

Many microorganisms and artificial microswimmers use helical appendages in order to generate locomotion. Though often rotated so as to produce thrust, some species of bacteria such Spiroplasma, Rhodobacter sphaeroides and Spirochetes induce movement by deforming a helical-shaped body. Recently, artificial devices have been created which also generate motion by deforming their helical body in a non-reciprocal way (A. Mourran et al. Adv. Mater. 29, 1604825, 2017). Inspired by these systems, we investigate the transport of a deforming helix within a viscous fluid. Specifically, we consider a swimmer that maintains a helical centreline and a single handedness while changing its helix radius, pitch and wavelength uniformly across the body. We first discuss how a deforming helix can create a non-reciprocal translational and rotational swimming stroke and identify its principle direction of motion. We then determine the leading-order physics for helices with small helix radius before considering the general behaviour for different configuration parameters and how these swimmers can be optimised. Finally, we explore how the presence of walls, gravity, and defects in the centreline allow the helical device to break symmetries, increase its speed, and generate transport in directions not available to helices in bulk fluids.

Students' Learning Experiences from Didactic Teaching Sessions Including Patient Case Examples as Either Text or Video: A Qualitative Study.

OBJECTIVES: The aim of this study was to explore medical students' learning experiences from the didactic teaching formats using either text-based patient cases or video-based patient cases with similar content. The authors explored how the two different patient case formats influenced students' perceptions of psychiatric patients and students' reflections on meeting and communicating with psychiatric patients. METHODS: The authors conducted group interviews with 30 medical students who volunteered to participate in interviews and applied inductive thematic content analysis to the transcribed interviews. RESULTS: Students taught with text-based patient cases emphasized excitement and drama towards the personal clinical narratives presented by the teachers during the course, but never referred to the patient cases. Authority and boundary setting were regarded as important in managing patients. Students taught with video-based patient cases, in contrast, often referred to the patient cases when highlighting new insights, including the importance of patient perspectives when communicating with patients. CONCLUSION: The format of patient cases included in teaching may have a substantial impact on students' patient-centeredness. Video-based patient cases are probably more effective than text-based patient cases in fostering patient-centered perspectives in medical students. Teachers sharing stories from their own clinical experiences stimulates both engagement and excitement, but may also provoke unintended stigma and influence an authoritative approach in medical students towards managing patients in clinical psychiatry.

Glycan-Functionalized Microgels for Scavenging and Specific Binding of Lectins.

Lectins are proteins with a well-defined carbohydrate recognition domain. Many microbial proteins such as bacterial toxins possess lectin or lectin-like binding domains to interact with cell membranes that are decorated with glycan recognition motifs. We report a straightforward way to prepare monodisperse and biocompatible polyethylene glycol microgels, which carry glycan motifs for specific binding to lectins. The sugar-functionalized colloids exhibit a wide mesh size and a highly accessible volume. The microgels are prepared via drop-based microfluidics combined with radical polymerization. GSII and ECL are used as model lectins that bind specifically to the corresponding carbohydrates, namely, GlcNAc and LacNAc. LacNAc microgels bind ECL with a high capacity and high affinity (Kd ≈ 0.5 to 1 µM), suggesting multivalent binding of the lectin to the LacNAc-decorated flexible microgel network. Glycan-functionalized microgels present a useful tool for lectin scavenging in biomedical applications.

Large-scale, thick, self-assembled, nacre-mimetic brick-walls as fire barrier coatings on textiles.

Highly loaded polymer/clay nanocomposites with layered structures are emerging as robust fire retardant surface coatings. However, time-intensive sequential deposition processes, e.g. layer-by-layer strategies, hinders obtaining large coating thicknesses and complicates an implementation into existing technologies. Here, we demonstrate a single-step, water-borne approach to prepare thick, self-assembling, hybrid fire barrier coatings of sodium carboxymethyl cellulose (CMC)/montmorillonite (MTM) with well-defined, bioinspired brick-wall nanostructure, and showcase their application on textile. The coating thickness on the textile is tailored using different concentrations of CMC/MTM (1-5 wt%) in the coating bath. While lower concentrations impart conformal coatings of fibers, thicker continuous coatings are obtained on the textile surface from highest concentration. Comprehensive fire barrier and fire retardancy tests elucidate the increasing fire barrier and retardancy properties with increasing coating thickness. The materials are free of halogen and heavy metal atoms, and are sourced from sustainable and partly even renewable building blocks. We further introduce an amphiphobic surface modification on the coating to impart oil and water repellency, as well as self-cleaning features. Hence, our study presents a generic, environmentally friendly, scalable, and one-pot coating approach that can be introduced into existing technologies to prepare bioinspired, thick, fire barrier nanocomposite coatings on diverse surfaces.

Chlorhexidine Loaded Cyclodextrin Containing PMMA Nanogels as Antimicrobial Coating and Delivery Systems.

Antimicrobial nanogels, aggregates, and films are prepared by complexation of the antiseptic and bacteriostatic agent chlorhexidine (CHX) for medical and dental applications. A series of α-, ß-, and γ-cyclodextrin methacrylate (CD-MA) containing hydrophobic poly(methyl methacrylate) (PMMA) based nanogels are loaded quantitatively with CHX in aqueous dispersion. The results show that CHX is enhancedly complexed by the use of CD-MA domains in the particles structure. ß-CD-MA nanogels present the highest uptake of CHX. Furthermore, it is observed that the uptake of CHX in nanogels is influenced by the hydrophobic PMMA structure. CHX acts as external cross-linker of nanogels by formation of 1:2 (CHX:CD-MA) inclusion complexes of two ß-CD-MA units on the surfaces of two different nanogels. The nanogels adsorb easily onto glass surfaces by physical self-bonding and formation of a dense crosslinked nanogel film. Biological tests of the applied CHX nanogels with regard to antimicrobial efficiency are successfully performed against Staphylococcus aureus.

High-Throughput Generation of Emulsions and Microgels in Parallelized Microfluidic Drop-Makers Prepared by Rapid Prototyping.

We describe the preparation of rapid prototyped parallelized microfluidic drop-maker devices. The manufacturing technique facilitates stacking of the drop-makers vertically on top of each other allowing for a reduced footprint and minimized dead-volume through efficient design of the distribution channels. We showcase the potential of the additive manufacturing technique for microfluidics and the performance of the parallelized device by producing large amounts of microgels with a diameter of ca. 500 µm, a size that is inaccessible using traditional synthetic approaches.

Stable biochemically micro-patterned hydrogel layers control specific cell adhesion and allow long term cyclic tensile strain experiments.

Poly(dimethylsiloxane) can be covalently coated with ultrathin NCO-sP(EO-stat-PO) hydrogel layers which permit covalent binding of cell adhesive moieties, while minimizing unspecific cell adhesion on non-functionalized areas. We applied long term uniaxial cyclic tensile strain (CTS) and revealed (a) the preservation of protein and cell-repellent properties of the NCO-sP(EO-stat-PO) coating and (b) the stability and bioactivity of a covalently bound fibronectin (FN) line pattern. We studied the adhesion of human dermal fibroblast (HDFs) on non-modified NCO-sP(EO-stat-PO) coatings and on the FN. HDFs adhered to FN and oriented their cell bodies and actin fibers along the FN lines independently of the direction of CTS. This mechanical long term stability of the bioactive, patterned surface allows unraveling biomechanical stimuli for cellular signaling and behavior to understand physiological and pathological cell phenomenon. Additionally, it allows for the application in wound healing assays, tissue engineering, and implant development demanding spatial control over specific cell adhesion.

Monolayer properties of asymmetrically substituted sexithiophene.

We present a structural comparison of monolayers on a SiO2 substrate of two asymmetrically substituted sexithiophenes (6T). Molecule 1 consists of 6T with a branched alkyl chain at one end only and shows a crystalline structure. In molecule 2, the bifunctional 6T has in addition at the other end a linear alkyl chain. It displays thermotropic liquid crystalline (LC) behavior. Both compounds form readily single molecular layers from solution. Remarkably, full monolayer coverage can be achieved before multilayer growth starts. LC properties promote preordering near the interface as well as exchange of molecules between the growing domains, thus regulating the domain sizes. As a result, the LC compound 2 forms single-molecule islands with larger domain sizes compared to compound 1. Surface X-ray investigations indicate that the 6T cores are tilted relative to the layer normal. The tilt angle is as large as 54° for compound 2 compared to 28° for compound 1. For molecule 2, interfacial constraints and packing requirements because of the asymmetric substitution cause a rather loosely organized core structure.

Nanogels with high active ß-cyclodextrin content as physical coating system with sustained release properties.

We present the application of nanogels with high functional ß-cyclodextrin (ß-CD) content as new and versatile method for the modification and protection of textiles. The complexation potential of covalently embedded ß-CD in nanogels is demonstrated for the common insecticide permethrin in aqueous environment. It is shown that permethrin containing ß-CD nanogels can be applied easily, homogeneously and safely on keratin fibers like wool fabrics and human hairs. The permethrin concentration on fibers is directly controlled by the permethrin content in nanogels. We tested the permanence of permethrin on treated fibers with regard to washing and UV fastness. Our results show that permethrin complexed in nanogels is removed from the textile during washing, but that the complexation of permethrin by ß-CD domains in the nanogels protects the active ingredient from UV degradation. Bioassay tests against the larvae of Tineola bisselliella and Anthrenocerus australis show that the activity of the ingredients does not decrease after complexation in ß-CD gels and it results in protection of the wool fibers against degradation by the insect larvae.

Unidirectional control of anisotropic wetting through surface modification of PDMS microstructures.

It has been shown before that anisotropically microstructured surfaces exhibit anisotropic wetting phenomena. This study presents a possibility to control the anisotropy of wetting by tailoring the surface chemistry. PDMS microchannels were permanently hydrophilized and subsequently functionalized further. Thereby, systematic studies on the effect of the surface modification on the wetting properties of microstructures have been possible. Importantly, we found that the wetting parallel to the groove strongly depended on the chemical modification of the structure although the wetting perpendicular to the groove is almost unaffected. Through immobilization of a monolayer of Si nanoparticles (SiNPs) exclusively on the elevations of the hydrogel-coated microstructured PDMS substrate, the anisotropic wetting could be selectively altered unidirectionally along the pattern direction.

Ultrathin sP(EO-stat-PO) hydrogel coatings are biocompatible and preserve functionality of surface bound growth factors in vivo.

Hydrogel coatings prepared from reactive star shaped polyethylene oxide based prepolymers (NCO-sP(EO-stat-PO)) minimize unspecific protein adsorption in vitro, while proteins immobilized on NCO-sP(EO-stat-PO) coatings retain their structure and biological function. The aim of the present study was to assess biocompatibility and the effect on early osseointegrative properties of a NCO-sP(EO-stat-PO) coating with additional RGD-peptides and augmentation with bone morphogenetic protein-4 (BMP) used on a medical grade high-density polyethylene (HDPE) base under in vivo circumstances. For testing of biocompatibility dishes with large amounts of bulk NCO-sP(EO-stat-PO) were implanted subcutaneously into 14 Wistar rats. In a second set-up functionalization of implants with ultrathin surface layers by coating ammonia-plasma treated HDPE with NCO-sP(EO-stat-PO), functionalization with linear RGD-peptides, and augmentation with RGD and BMP-4 was analyzed. Therefore, implants were placed subcutaneously in the paravertebral tissue and transcortically in the distal femur of another 14 Wistar rats. Both tests revealed no signs of enhanced inflammation of the surrounding tissue analyzed by CD68, IL-1ß-/TNF-α-antibody staining, nor systemic toxic reactions according to histological analysis of various organs. The mean thickness of the fibrous tissue surrounding the femoral implants was highest in native HDPE-implants and tended to be lower in all NCO-sP(EO-stat-PO) modified implants. Micro-CT analysis revealed a significant increase of peri-implant bone volume in RGD/BMP-4 coated samples. These results demonstrate that even very low amounts of surface bound growth factors do have significant effects when immobilized in an environment that retains their biological function. Hence, NCO-sP(EO-stat-PO)-coatings could offer an attractive platform to improve integration of orthopedic implants.

Molecular interaction of a new antibacterial polymer with a supported lipid bilayer measured by an in situ label-free optical technique.

The interaction of the antibacterial polymer-branched poly(ethylene imine) substituted with quaternary ammonium groups, PEO and alkyl chains, PEI25QI5J5A815-with a solid supported lipid bilayer was investigated using surface sensitive optical waveguide spectroscopy. The analysis of the optogeometrical parameters was extended developing a new composite layer model in which the structural and optical anisotropy of the molecular layers was taken into consideration. Following in situ the change of optical birefringence we were able to determine the composition of the lipid/polymer surface layer as well as the displacement of lipid bilayer by the antibacterial polymer without using additional labeling. Comparative assessment of the data of layer thickness and optical anisotropy helps to reveal the molecular mechanism of antibacterial effect of the polymer investigated.

The role of SNAP-tag in technical approaches.

Biosensors are used for a variety of applications in medicine and biology. A critical step during the development of such devices is the coordination of biological and technical requirements. The design of the device, as well as of the sample chamber and its functionalized surface is of great importance. Depending on the surface, the method of coupling of the desired receptor has to be adapted to guarantee functionality and biological activity during the measuring process. By using the SNAP-tag technology, a site-specific coupling of molecules with unaltered activity to a variety of O(6)-benzylguanine functionalized surfaces is possible, making it a versatile tool for the setup of biomedical devices.

Microengineered PEG hydrogels: 3D scaffolds for guided cell growth.

Designing three-dimensional (3D) scaffolds for selective manipulation of cell growth is of high relevance for applications in regenerative medicine. Especially, scaffolds with oriented morphologies bear high potential to guide the restoration of specific tissues. The fabrication of hydrogel scaffolds that support long-term survival, proliferation, and unidirectional growth of embedded cells is presented here. Parallel channel structures are introduced into the bulk hydrogels by uniaxial freezing, providing stable, and uniform porosity suitable for cell invasion (pore diameters of 5-15 µm). In vitro assessment of the scaffolds with murine fibroblasts (NIH L929) shows a remarkable unidirectional movement along the channels, with the cells traveling several millimeters through the hydrogel.

Tenside-free preparation of nanogels with high functional ß-cyclodextrin content.

We present the preparation of ultrafine (R(h), 50 -150 nm) nanogels through tenside-free condensation of reactive prepolymers with ß-cyclodextrin (ß-CD) in water. These nanogels possess a maximum content of 60 wt % functional ß-CD that can form inclusion complexes as demonstrated by dye sorption with phenolphthalein. Aside of this extremely high uptake capacity to hydrophobic molecules, the nanogels also show good adhesion to surfaces in homogeneous distribution with size of R(h) of 25 nm under dry conditions.

Membrane affinity and antibacterial properties of cationic polyelectrolytes with different hydrophobicity.

The antibacterial behavior of cationic polyelectrolytes is studied using model membrane experiments and in vitro bacterial investigations. The molecular interaction with lipid films is evaluated by the degree of penetration of the polymers into Langmuir monolayers of neutral or negatively charged lipids. The polymer/lipid interaction results in structural changes of the penetrated lipid layer visualized using AFM. The polymers are found to be effective in inhibiting the proliferation of E. coli, B. subtilis and S. aureus. The influence of the chemical structure on the functional behavior is related to the conformational properties. An optimum structure is identified on the basis of antibacterial and hemolytic tests as well as membrane-destroying efficacy of the antimicrobial polymers.

Solution-processable septithiophene monolayer transistor.

Septithiophene with endgroups designed to form liquid crystalline phases and allows controlled deposition of an electrically connected monolayer. Field effect mobilies mobilities of charge carriers and spectroscopic properties of the monolayer provide evidence of sustainable transport and delocalization of the excitation through intermolecular interactions within the layer.