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Biofilm formation and detachment in drinking water distribution systems (DWDS) can lead to several operational issues. Here, an alternative biofilm control strategy of limiting bacterial adhesion by application of a poly(N-isopropylmethacrylamide)-based nanogel coating on DWDS pipe walls was investigated. The nanogel coatings were successfully deposited on surfaces of four polymeric pipe materials commonly applied in DWDS construction. Nanogel-coated and non-coated pipe materials were characterized in terms of their surface hydrophilicity and roughness. Four DWDS relevant bacterial strains, representing Sphingomonas and Pseudomonas, were used to evaluate the anti-adhesive performance of the coating in 4 h adhesion and 24 h biofilm assays. The presence of the nanogel coating resulted in adhesion reduction up to 97%, and biofilm reduction up to 98%, compared to non-coated surfaces. These promising results motivate further investigation of nanogel coatings as a strategy for biofilm prevention in DWDS.

Dynamic covalent chemistry (DCC) has proven to be a valuable tool in creating fascinating molecules, structures, and emergent properties in fully synthetic systems. Here we report a system that uses two dynamic covalent bonds in tandem, namely disulfides and hydrazones, for the formation of hydrogels containing biologically relevant ligands. The reversibility of disulfide bonds allows fiber formation upon oxidation of dithiol-peptide building block, while the reaction between NH-NH2 functionalized C-terminus and aldehyde cross-linkers results in a gel. The same bond-forming reaction was exploited for the "decoration" of the supramolecular assemblies by cell-adhesion-promoting sequences (RGD and LDV). Fast triggered gelation, cytocompatibility and ability to "on-demand" chemically customize fibrillar scaffold offer potential for applying these systems as a bioactive platform for cell culture and tissue engineering.

Fibrosis results from aberrant wound healing and is characterized by an accumulation of extracellular matrix, impairing the function of an affected organ. Increased deposition of extracellular matrix proteins, disruption of matrix degradation, but also abnormal post‐translational modifications alter the biochemical composition and biophysical properties of the tissue microenvironment – the stroma. Macrophages are known to play an important role in wound healing and tissue repair, but the direct influence of fibrotic stroma on macrophage behaviour is still an under‐investigated element in the pathogenesis of fibrosis. In this review, the current knowledge on interactions between macrophages and (fibrotic) stroma will be discussed from biochemical, biophysical, and cellular perspectives. Furthermore, we provide future perspectives with regard to how macrophage–stroma interactions can be examined further to ultimately facilitate more specific targeting of these interactions in the treatment of fibrosis. © 2021 The Authors. The Journal of Pathology published by John Wiley & Sons, Ltd. on behalf of The Pathological Society of Great Britain and Ireland.

Designing new dynamic matrices in combination with a highly diverse material formation approach as Pickering emulsions provides the tools to engineer innovative dynamic porous microstructures in a highly controllable fashion. Here, nanogels (nGels) are used, which exhibit dynamic covalent cross-linking capabilities, as surface stabilizing agents in view of their highly controllable physiochemical properties. The method provides the successful formation of dynamic covalent cross-linked hydrogel microstructures based on ketone and amine-functionalized nGels using Pickering emulsions. In this system, a pH-triggerable responsive behavior is incorporated. The physiochemical properties of the resulting microstructure can be further tailored by modifying the intramolecular interactions at the interface, making these systems interesting for a wide range of applications.

The implementation of nanotechnology to develop efficient antimicrobial systems has a significant impact on the prospects of the biomedical field. Nanogels are soft polymeric particles with an internally cross-linked structure, which behave as hydrogels and can be reversibly hydrated/dehydrated (swollen/shrunken) by the dispersing solvent and external stimuli. Their excellent properties, such as biocompatibility, colloidal stability, high water content, desirable mechanical properties, tunable chemical functionalities, and interior gel-like network for the incorporation of biomolecules, make them fascinating in the field of biological/biomedical applications. In this review, various approaches will be discussed and compared to the newly developed nanogel technology in terms of efficiency and applicability for determining their potential role in combating infections in the biomedical area including implant-associated infections., Graphical abstract Image 1, Highlights • Nanogels are novel soft nanoparticles with high potential impact with the biomedical field. • Nanogels are applied both as bioactive materials in suspension and at interfaces. • Hydrogel nanoparticles have tremendous impact on infection related issues. • Nanogels offer antifouling possibilities and provided controlled release possibilities. • Nanogels can be tuned in their physicochemical properties to match the biomedical application.

The complex interaction of cells with biomaterials (i.e., materiobiology) plays an increasingly pivotal role in the development of novel implants, biomedical devices, and tissue engineering scaffolds to treat diseases, aid in the restoration of bodily functions, construct healthy tissues, or regenerate diseased ones. However, the conventional approaches are incapable of screening the huge amount of potential material parameter combinations to identify the optimal cell responses and involve a combination of serendipity and many series of trial-and-error experiments. For advanced tissue engineering and regenerative medicine, highly efficient and complex bioanalysis platforms are expected to explore the complex interaction of cells with biomaterials using combinatorial approaches that offer desired complex microenvironments during healing, development, and homeostasis. In this review, we first introduce materiobiology and its high-throughput screening (HTS). Then we present an in-depth of the recent progress of 2D/3D HTS platforms (i.e., gradient and microarray) in the principle, preparation, screening for materiobiology, and combination with other advanced technologies. The Compendium for Biomaterial Transcriptomics and high content imaging, computational simulations, and their translation toward commercial and clinical uses are highlighted. In the final section, current challenges and future perspectives are discussed. High-throughput experimentation within the field of materiobiology enables the elucidation of the relationships between biomaterial properties and biological behavior and thereby serves as a potential tool for accelerating the development of high-performance biomaterials.

Although transplantation of single genes in yeast plays a key role in elucidating gene functionality in metazoans, technical challenges hamper humanization of full pathways and processes. Empowered by advances in synthetic biology, this study demonstrates the feasibility and implementation of full humanization of glycolysis in yeast. Single gene and full pathway transplantation revealed the remarkable conservation of glycolytic and moonlighting functions and, combined with evolutionary strategies, brought to light context-dependent responses. Human hexokinase 1 and 2, but not 4, required mutations in their catalytic or allosteric sites for functionality in yeast, whereas hexokinase 3 was unable to complement its yeast ortholog. Comparison with human tissues cultures showed preservation of turnover numbers of human glycolytic enzymes in yeast and human cell cultures. This demonstration of transplantation of an entire essential pathway paves the way for establishment of species-, tissue-, and disease-specific metazoan models.

3D printed hydrogels have emerged as a novel tissue engineering and regeneration platform due to their ability to provide a suitable environment for cell growth. To obtain a well-defined scaffold with good post-printing shape fidelity, a proper hydrogel ink formulation plays a crucial role. In this regard, alginate has received booming interest owing to its biocompatibility, biodegradability, easy functionalization, and fast gelling behavior. Hence, this review highlights the significance of alginate-based hydrogel inks for fabricating 3D printed scaffolds for bone and cartilage regeneration. Herein, we discuss the fundamentals of direct extrusion 3D bioprinting method and provide a comprehensive overview of various alginate-based hydrogel ink formulations that have been used so far. We also summarize the requirements of hydrogel inks and 3D printed scaffolds to achieve similarity to the native tissue environment. Finally, we discuss the challenges, and research directions relevant for future clinical translation.

A multimodal approach for hydrogel‐based nanoparticles was developed to selectively allow molecular conjugated species to either be released inside the cell or remain connected to the polymer network. Using the intrinsic difference in reactivity between esters and amides, nanogels with an amide‐conjugated dye could be tracked intracellularly localizing next to the nucleus, while ester‐conjugation allowed for liberation of the molecular species from the hydrogel network inside the cell, enabling delivery throughout the cytoplasm. The release was a result of particle exposure to the intracellular environment. The conjugation approach and polymer network building rely on the same chemistry and provide a diverse range of possibilities to be used in nanomedicine and theranostic approaches., Nanogels are highly versatile hydrogel nanoparticles that have much potential in nanomedicine and theranostics. The key issue remains to control the location of release of active conjugated moieties and controlling when and if conjugated structures will be liberated. Here, a versatile approach is presented that allows selective intracellular release of small molecules, which would tremendously affect the field of nanomedicine.

Controllable molecular release from delivery vehicles is essential to successfully reduce drug toxicity and improve therapeutic efficacy. Light-powered hydrophobic molecular motors were therefore incorporated in liposomes to use molecular rotation to facilitate on-demand release. The extent of the release was precisely controlled by irradiation times, providing a simple yet sophisticated responsive molecular nanocarrier. This journal is

Background In-stent restenosis (ISR) is a complex disease that occurs after coronary stenting procedures. The development of quality materials and improvement of our understanding on significant factors regulating ISR are essential for enhancing prognosis. Vascular smooth muscle cells (VSMCs) are the main constituent cells of blood vessel walls, and dysfunction of VMSCs can exacerbate ISR. Accordingly, in this study, we explored the influence of wrinkled material topography on the biological functions of VSMCs. Methods Polydimethylsiloxane with a wrinkled topography was synthesized using elastomer base and crosslinking and observed by atomic force microscopy. VSMC proliferation, apoptosis, and morphology were determined by Cell Counting Kit-8 assays, fluorescence-assisted cell sorting, and phalloidin staining. α-Smooth muscle actin (α-SMA), major histocompatibility complex (MHC), and calponin 1 (CNN-1) expression levels were measured by quantitative real-time polymerase chain reaction and western blotting. Moreover, p53 and cleaved caspase-3 expression levels were evaluated by western blotting in VSMCs to assess apoptotic induction. Results Surface topographies were not associated with a clear orientation or elongation of VSMCs. The number of cells was increased on wrinkled surfaces (0.7 μm in amplitude, and 3 μm in wavelength [W3]) compared with that on other surfaces, contributing to continuously increased cell proliferation. Moreover, interactions of VSMCs with the W3 surface suppressed phenotypic switching, resulting in ISR via regulation of α-SMA, calponin-1, and SM-MHC expression. The surface with an amplitude of 0.05 μm and a wavelength of 0.5 μm (W0.5) promoted apoptosis by inducing caspase 3 and p53 activities. Conclusion Introduction of aligned topographies on biomaterial scaffolds could provide physical cues to modulate VSMC responses for engineering vascular constructs. Materials with wrinkled topographies could have applications in the development of stents to reduce ISR.

Cell-derived matrices (CDMs) are an interesting alternative to conventional sources of extracellular matrices (ECMs) as CDMs mimic the natural ECM composition better and are therefore attractive as a scaffolding material for regulating the functions of stem cells. Previous research on stem cell differentiation has demonstrated that both surface topography and CDMs have a significant influence. However, not much focus has been devoted to elucidating possible synergistic effects of CDMs and topography on osteogenic differentiation of human bone marrow-derived mesenchymal stem cells (hBM-MSCs). In this study, polydimethylsiloxane (PDMS)-based anisotropic topographies (wrinkles) with various topography dimensions were prepared and subsequently combined with native ECMs produced by human fibroblasts that remained on the surface topography after decellularization. The synergistic effect of CDMs combined with topography on osteogenic differentiation of hBM-MSCs was investigated. The results showed that substrates with specific topography dimensions, coated with aligned CDMs, dramatically enhanced the capacity of osteogenesis as investigated using immunofluorescence staining for identifying osteopontin (OPN) and mineralization. Furthermore, the hBM-MSCs on the substrates decorated with CDMs exhibited a higher percentage of (Yes-associated protein) YAP inside the nucleus, stronger cell contractility, and greater formation of focal adhesions, illustrating that enhanced osteogenesis is partly mediated by cellular tension and mechanotransduction following the YAP pathway. Taken together, our findings highlight the importance of ECMs mediating the osteogenic differentiation of stem cells, and the combination of CDMs and topography will be a powerful approach for material-driven osteogenesis.

High-throughput screening (HTS) methods based on anisotropically topography gradients have been broadly used to investigate the interactions between cells and biomaterials. However, few studies focus on the optimum parameters of topography for osteogenic differentiation because the structures of topography are complex with multiple combinations of parameters. In this study, we developed polydimethylsiloxane (PDMS)-based wrinkled topography gradients (amplitudes between 144 and 2854 nm and wavelengths between 0.91 and 13.62 mu m) and decoupled the wavelength and amplitude via imprinting lithography and shielded plasma oxidation. The PDMS wrinkle gradient was then integrated with the bottomless 96-well plate to constitute the wrinkled HTS platform, which consists of 70 different wrinkle parameters. From the in vitro culture of bone marrow stem cells, it was observed that aligned topography has an important influence on the macroscopic cell behavior (i.e., cell area, elongation, and nucleus area). Furthermore, the optimum wrinkle parameter (wavelength: 1.91 mu m; amplitude: 360 nm) for osteogenic differentiation of stem cells was determined via this screening plate approach. This screening platform is not only beneficial for a better understanding of the interactions between topography and biomaterials but also advances the development of bone tissue engineering developments.

Biophysical stimuli including topography play a crucial role in the regulation of cell morphology, adhesion, migration, and cytoskeleton organization and have been known to be important in biomaterials design for tissue engineering. However, little is known about the individual effects of topographic direction, structure repetition, and feature size of the substrate on which wound healing occurs. We report on the design of a topographical gradient with wavelike features that gradually change in wavelength and amplitude, which provides an efficient platform for an in vitro wound healing assay to investigate fibroblast migration. The wound coverage rate was measured on selected areas with wavelength sizes of 2, 5, and 8 mu m in perpendicular and parallel orientations. Furthermore, a method was developed to produce independently controlled wavelength and amplitude and study which parameter has greater influence. Cell movement was guided by topographical properties, with a lower wrinkle wavelength (2 mu m) eliciting the fastest migration speed, and the migration speed increased with decreasing amplitude. However, when the amplitudes were matched, cells migrated faster on a larger wavelength. This study also highlights the sensitivity of fibroblasts to the topographic orientation, with cells moving faster in the parallel direction of the topography. The overall behavior indicated that the wavelength and amplitude both play an important role in directing cell migration. The collective cell migration was found not to be influenced by altered cell proliferation. These findings provide key insights into topography-triggered cell migration and indicate the necessity for better understanding of material-directed wound healing for designing bio-inductive biomaterials.

Endothelial cell (EC) monolayers located in the inner lining of blood vessels serve as a semipermeable barrier between circulating blood and surrounding tissues. The structure and function of the EC monolayer affect the recruitment and adhesion of monocytes, which plays a pivotal role in the development of inflammation and atherosclerosis. Here we investigate the effect of material wrinkled topographies on the responses of human umbilical vein endothelial cells (HUVECs) and adhesion of monocytes to HUVECs. It is found that HUVEC responses are non-linearly mediated by surface topographies with different dimensions. Specifically, more cell elongation and better cell orientation on the wrinkled surface with a 3.5 μm amplitude and 10 μm wavelength (W10) are observed compared to other surfaces. The proliferation rate of HUVECs on the W10 surface is higher than that on other surfaces due to more 5-ethynyl-2′-deoxyuridine (EdU) detected on the W10 surface. Also, greater expression of inflammatory cytokines from HUVECs and adhesion of monocytes to HUVECs on the W10 surface is shown than other surfaces due to greater expression of p-AKT and ICAM, respectively. This study offers a new in vitro system to understand the interplay between HUVEC monolayers and monocytes mediated by aligned topographies, which may be useful for vascular repair and disease modeling for drug testing.

Mimicking the native extracellular matrix (ECM) as a cell culture scaffold has long attracted scientists from the perspective of supramolecular chemistry for potential application in regenerative medicine. However, the development of the next-generation synthetic materials that mimic key aspects of ECM, with hierarchically oriented supramolecular structures, which are simultaneously highly dynamic and responsive to external stimuli, remains a major challenge. Herein, we present supramolecular assemblies formed by motor amphiphiles (MAs), which mimic the structural features of the hydrogel nature of the ECM and additionally show intrinsic dynamic behavior that allow amplifying molecular motions to macroscopic muscle-like actuating functions induced by light. The supramolecular assembly (named artificial muscle) provides an attractive approach for developing responsive ECM mimetic scaffolds for human bone marrow-derived mesenchymal stem cells (hBM-MSCs). Detailed investigations on the photoisomerization by nuclear magnetic resonance and UV-vis absorption spectroscopy, assembled structures by electron microscopy, the photoactuation process, structural order by X-ray diffraction, and cytotoxicity are presented. Artificial muscles of MAs provide fast photoactuation in water based on the hierarchically anisotropic supramolecular structures and show no cytotoxicity. Particularly important, artificial muscles of MAs with adhered hBM-MSCs still can be actuated by external light stimulation, showing their ability to convert light energy into mechanical signals in biocompatible systems. As a proof-of-concept demonstration, these results provide the potential for building photoactuating ECM mimetic scaffolds by artificial muscle-like supramolecular assemblies based on MAs and offer opportunities for signal transduction in future biohybrid systems of cells and MAs.

3D bioprinting is a powerful fabrication technique in biomedical engineering, which is currently limited by the number of available materials that meet all physicochemical and cytocompatibility requirements for biomaterial inks. Inspired by the key role of coacervations in the extrusion and spinning of many natural materials, hyaluronic acid-chitosan complex coacervates are proposed here as tunable biomaterial inks. Complex coacervates are obtained through an associative liquid-liquid phase separation driven by electrostatic attraction between oppositely charged macromolecules. They offer bioactive properties as well as facile modulation of their mechanical properties through mild physicochemical changes in the environment, rendering them attractive for 3D bioprinting. Fine-tuning the salt concentration, pH, and molecular weight of the constituent polymers results in biomaterial inks that are printable in air and water. The biomaterial ink, initially a viscoelastic fluid, transitions into a viscoelastic solid upon printing due to dehydration (for printing in air) or due to a change in pH and ionic composition (for printing in water). Consequently, scaffolds printed using the complex coacervate inks are stable without the need for post-printing processing. Cell culture scaffolds fabricated in this way are cytocompatible and show long-term topological stability. These results pave the way to a new class of easy-to-handle tunable biomaterials for biofabrication.

The strength of the extracellular matrix (ECM) is that it is hierarchical in terms of matrix built-up, matrix density and fiber structure, which allows for hormones, cytokines, and other small biomolecules to be stored within its network. The ECM-like hydrogels that are currently used do not possess this ability, and long-term storage, along with the need for free diffusion of small molecules, are generally incompatible requirements. Nanogels are able to fulfill the additional requirements upon successful integration. Herein, a stable hierarchical nanogel–gelatin methacryloyl (GelMA) composite hydrogel system is provided by covalently embedding nanogels inside the micropore network of GelMA hydrogel to allow a controlled local functionality that is not found in a homogenous GelMA hydrogel. Nanogels have emerged as a powerful tool in nanomedicine and are highly versatile, due to their simplicity of chemical control and biological compatibility. In this study, an N-isopropylacrylamide-based nanogel with primary amine groups on the surface was modified with methacryloyl groups to obtain a photo-cross-linking ability similar to GelMA. The nanogel-GelMA composite hydrogel was formed by mixing the GelMA and the photo-initiator within the nanogel solution through UV irradiation. The morphology of the composite hydrogel was observed by scanning electron microscopy, which clearly showed the nanogel wrapped within the GelMA network and covering the surface of the pore wall. A release experiment was conducted to prove covalent bonding and the stability of the nanogel inside the GelMA hydrogel. In addition, 3D printability studies showed that the nanogel-GelMA composite ink is printable. Therefore, the suggested stable hierarchical nanogel-GelMA composite hydrogel system has great potential to achieve the in situ delivery and controllable release of bioactive molecules in 3D cell culture systems.

Tissue engineering of skeletal muscle aims to replicate the parallel alignment of myotubes on the native tissue. Directional topography gradients allow the study of the influence of topography on cellular orientation, proliferation, and differentiation, resulting in yield cues and clues to develop a proper in vitro environment for muscle tissue engineering. In this study, we used a polydimethylsiloxane-based substrate containing an aligned topography gradient with sinusoidal features ranging from wavelength (lambda) = 1,520 nm and amplitude (A) =176 nm to lambda = 9,934 nm and A = 2,168 nm. With this topography gradient, we evaluated the effect of topography on human myoblasts distribution, dominant orientation, cell area, nuclei coverage, cell area per number of nuclei, and nuclei area of myotubes. We showed that human myoblasts aligned and differentiated irrespective of the topography section. In addition, aligned human myotubes showed functionality and maturity by contracting spontaneously and nuclei peripheral organization resembling natural myotubes.

Bacterial infection is a severe problem especially when associated with biomedical applications. This study effectively demonstrates that poly-N-isopropylmethacrylamide based microgel coatings prevent bacterial adhesion. The coating preparation via a spraying approach proved to be simple, and both cost and time efficient creating a homogeneous dense microgel monolayer. In particular, the influence of cross-linking density, microgel size, and coating thickness was investigated on the initial bacterial adhesion. Adhesion of Staphylococcus aureus ATCC 12600 was imaged using a parallel plate flow chamber setup, which gave insights in the number of the total bacteria adhering per unit area onto the surface and the initial bacterial deposition rates. All microgel coatings successfully yielded more than 98% reduction in bacterial adhesion. Bacterial adhesion depends both on the cross-linking density/stiffness of the microgels and on the thickness of the microgel coating. Bacterial adhesion decreased when a lower cross-linking density was used at equal coating thickness and at equal cross-linking density with a thicker microgel coating. The highest reduction in the number of bacterial adhesion was achieved with the microgel that produced the thickest coating (h = 602 nm) and had the lowest cross-linking density. The results provided in this paper indicate that microgel coatings serve as an interesting and easy applicable approach and that it can be fine-tuned by manipulating the microgel layer thickness and stiffness.

Transport of therapeutics across the blood-brain barrier (BBB) is a fundamental requirement for effective treatment of numerous brain diseases. However, most therapeutics (>500 Da) are unable to permeate through the BBB and do not achieve therapeutic doses. Nanoparticles (NPs) are being investigated to facilitate drug delivery to the brain. Here, we investigate the effect of nanoparticle stiffness on NP transport across an in vitro BBB model. To this end, fluorescently labeled poly(N-isopropylmethacrylamide) (p(NIPMAM)) nanogels' stiffness was varied by the inclusion of 1.5 mol% (NG1.5), 5 mol% (NG5), and 14 mol% (NG14) N,N'-methylenebis(acrylamide) (BIS) cross-linker and nanogel uptake and transcytosis was quantified. The more densely cross-linked p(NIPMAM) nanogels showed the highest level of uptake by polarized brain endothelial cells, whereas the less densely cross-linked nanogels demonstrated the highest transcytotic potential. These findings suggest that nanogel stiffness has opposing effects on nanogel uptake and transcytosis at the BBB. (C) 2021 The Authors. Published by Elsevier Inc.

Understanding the response of endothelial cells to aligned myotubes is important to create an appropriate environment for tissue-engineered vascularized skeletal muscle. Part of the native tissue environment is the extracellular matrix (ECM). The ECM is a supportive scaffold for cells and allows cellular processes such as proliferation, differentiation, and migration. Interstitial matrix and basal membrane both comprise proteinaceous and polysaccharide components for strength, architecture, and volume retention. Virtually all cells are anchored to their basal lamina. One of the physical factors that affects cell behavior is topography, which plays an important role on cell alignment. We tested the hypothesis that topography-driven aligned human myotubes promote and support vascular network formation as a prelude to in vitro engineered vascularized skeletal muscle. Therefore, we used a PDMS-based topography substrate to investigate the influence of pre-aligned myotubes on the network formation of microvascular endothelial cells. The aligned myotubes produced a network of collagen fibers and laminin. This network supported early stages of endothelial network formation.

Introduction The presence of biofilms in drinking water distribution systems (DWDS) leads to a number of issues, i.e. secondary (biological) drinking water contamination, pipe damage and increased flow resistance. Among other operational factors, the selection of pipe material plays an important role in biofilm development. Up to now, the studies that have investigated this correlation provide contradictory results in terms of which material might be the most advantageous in the DWDS biofilm control strategy. Hence, to understand the influence of pipe material on biofilm formation, we focused on developing a standardized methodology that allows a multi-stage assessment of biofilm development on real pipe materials. Results Development of the methodology consisted of three steps: 1) material coupon sterilization, 2) biofilm cultivation and 3) biofilm analysis, using transparent polyvinyl chloride (PVC) as a study material. For the coupon sterilization, methods utilizing immersion in different disinfectant solutions with and without pre-cleaning by rubbing the coupons in a surfactant solution. The results showed that mechanical cleaning before washing is crucial and without it, reproducible sterilization was difficult to achieve. Biofilm formation on the PVC coupons was performed in a 6-well plate assay (24, 48 and 72 h; under agitation) using DWDS biofilm strains (Sphingomonas spp. and Pseudomonas extremorientalis) and Pseudomonas aeruginosa as a positive control. Bacterial fitness and ability to secrete EPS and form biofilms on the PVC surfaces were tested by monitoring optical density (OD600 nm), chemical oxygen demand (COD) and protein concentration. The formed biofilm and the morphology of attached bacteria were visualized using crystal violet staining (that allow qualitative (bright field microscopy) and quantitative (OD at 570 nm) evaluation), by scanning electron microscopy (SEM) and DNA staining (4′,6-diamidino-2-phenylindole; DAPI) with fluorescence microscopy. Combination of those techniques gave a complete overview of patterns involved in biofilm development by selected drinking water bacterial strains in presence of a PVC surface. The developed methodology was also applied for the analysis of bacterial growth on real-grade pipe materials, such as PVC and polyethylene (PE), to understand their role in biofilm formation. Conclusions Implementation of various analytical and microscopic techniques is important in understanding mechanisms behind biofilm development in DWDS and the influence of pipe material in the process. The proposed approach allows the observation of biofilm formation in time, but also of the typical bacterial morphology of attached cells. In this study it was shown that to obtain reproducible results, it is crucial to select an appropriate sterilization technique and the influence of mechanical cleaning cannot be ignored in preparation of polymeric surfaces.

The interface between materials and cells plays a critical role in many biomedical applications. Inspired by the hierarchical architecture of collagen, most abundant structure in the extracellular matrix (ECM), a multiscale hierarchical topography is designed to mimic the collagen nano/micro hierarchical topography. It is hypothesized that the ECM topography affects osteogenesis of human mesenchymal stem cells but until now, it cannot be studied without the biochemical and mechanical influences of the ECM. The multiscale hierarchical topography is achieved by innovatively using sequentially aligned topography preparation via a silicone stretch-oxidation-release method and imprinting lithography. The anisotropically hierarchical topography influences stem cell morphology, orientation, and osteogenic differentiation. Intriguingly, the design resembling that of assembled collagen, exhibits the highest degree of osteogenesis. The hierarchical topotaxis effects are further exemplified by the enhanced vinculin expression, cell contractility, and more pronounced nuclear translocation of Yes-associated protein with the collagen-mimicking topography, indicative for enhanced osteogenesis. The developed multiscale hierarchical system provides insights into the importance of specific biological ECM-like topography by decoupling the biochemical influence. Various diseases, cancer, osteoarthritis, and fibrosis display impaired ECM structures, and therefore this system may have a great potential for tissue engineering approaches and developing in vitro disease models.

Biophysical factors such as anisotropic topography composed of micro/nanosized structures are important for directing the fate of human bone marrow-derived mesenchymal stem cells (hBM-MSCs) and have been applied to neuronal differentiation. Via high-throughput screening (HTS) methods based on topography gradients, the optimum topography is determined and translated toward a hierarchical architecture designed to mimic the nerve nano/microstructure. The polydimethylsiloxane (PDMS)-based topography gradient with amplitudes (A) from 541 to 3073 nm and wavelengths (W) between 4 and 30 µm is developed and the fate commitment of MSC toward neuron lineage is investigated. The hierarchical structures, combining nano- and microtopography (W0.3/W26 parallel/perpendicular) are fabricated to explore the combined topography effects on neuron differentiation. From the immunofluorescent staining results (Tuj1 and MAP2), the substrate characterized by W: 26 µm; A: 2.9 µm shows highest potential for promoting neurogenesis. Furthermore, the hierarchical features (W0.3/W26 parallel) significantly enhance neural differentiation. The hBM-MSCs on the hierarchical substrates exhibit a significantly lower percentage of nuclear Yes-associated protein (YAP)/TAZ and weaker cell contractility indicating that the promoted neurogenesis is mediated by the cell tension and YAP/TAZ pathway. This research provides new insight into designing biomaterials for applications in neural tissue engineering and contributes to the understanding of topography-mediated neuronal differentiation.

In this contribution, we describe ways to introduce additional complexity and functionality to protein mediated capsule formation based on biomineralization in Pickering templated systems in order to enable possible post-mineralization modifications. Here the shell morphology is influenced by addition of ionic additives to the reaction system which significantly alters the surface structure. By changing the oil-phase (tetraethyl orthosilicate), even more complexity is introduced as well as reactive groups by adding (3-aminopropyl)trimethoxysilane to the oil phase. The incorporated amino-functionality is easily addressed via mild peptide coupling reaction.

Topography-driven alterations in cell morphology tremendously influence cell biological processes, particularly stem cell differentiation. Aligned topography is known to alter the cell shape, which we anticipated to also induce altered physical properties of the cell. Here, we show that topography has a significant influence on single cell stiffness of human bone marrow derived-Mesenchymal Stem Cells (hBM-MSCs) and the osteogenic differentiation of these. Aligned topographies were used to control the cell elongation, depicted as the cell aspect ratio (C-AR). Intriguingly, an equal C-AR elicited from different topographies, resulted in highly altered differentiation behavior and the underlying single cell mechanics was found to be critical. The cell behavior was found to be focal adhesion-mediated and induced stiffness alterations rather than just influencing the cell elongation. The effect was further corroborated by investigations of the transcriptional regulators YAP. Our study provides insight into how mechanical properties of the cell, which are stimulated by topography, modulate the osteogenesis of hBM-MSCs, which is beneficial for improving the understanding of interactions between stem cells and topography for developing applications of tissue engineering and regenerative medicine.

Molecular motion of rotating motors delegates surface-adsorbed protein–stem cell interactions., Artificial rotary molecular motors convert energy into controlled motion and drive a system out of equilibrium with molecular precision. The molecular motion is harnessed to mediate the adsorbed protein layer and then ultimately to direct the fate of human bone marrow–derived mesenchymal stem cells (hBM-MSCs). When influenced by the rotary motion of light-driven molecular motors grafted on surfaces, the adsorbed protein layer primes hBM-MSCs to differentiate into osteoblasts, while without rotation, multipotency is better maintained. We have shown that the signaling effects of the molecular motion are mediated by the adsorbed cell-instructing protein layer, influencing the focal adhesion–cytoskeleton actin transduction pathway and regulating the protein and gene expression of hBM-MSCs. This unique molecular-based platform paves the way for implementation of dynamic interfaces for stem cell control and provides an opportunity for novel dynamic biomaterial engineering for clinical applications.

New high-throughput technologies for cell–material interaction studies provide researchers with powerful tools to speed up research in the field of biomaterial–cell interactions. However, sharing technologies is often difficult due to the necessity of specific knowledge and experiences. Engineered surfaces can elucidate effects of surface topography on cell behavior, which is of critical value for gaining control over cellular processes. Here, the translation of a gradient-based high-throughput cell screening approach for aligned nano/micro topographies interacting with cells is presented. An aligned topography 96-well plate is created by upscaling of highly specific gradient technology. The resulting cell culture dishes are compatible with general laboratory and imaging equipment, and the platform allows for studying cell behavior with regard to adhesion and alignment. The challenge lies in increasing the dimensions of the previous 1 × 1 cm gradient topography substrate, to be able to cover the span of a 96-well plate and translate it into a standardized cell-screening tool. Adhesion experiments of human bone marrow derived mesenchymal stem cells confirm the standardization, compatibility, and usability of the technology. In the process of using multi-system imaging and analysis, it becomes apparent that future challenges need to include universally applied data analysis approaches.

Multifunctional nanogel coatings provide a promising antimicrobial strategy against biomedical implant-associated infections. Nanogels can create a hydrated surface layer to promote antifouling properties effectively. Further modification of nanogels with quaternary ammonium compounds (QACs) potentiates antimicrobial activity owing to their positive charges along with the presence of a membrane-intercalating alkyl chain. This study effectively demonstrates that poly(N-isopropylacrylamide-coN-[3(dimethylamino)propyl]methacrylamide) (P(NIPAM-co-DMAPMA)-based nanogel coatings possess antifouling behavior against S. aureus ATCC 12600, a Gram-positive bacterium. Through the tertiary amine in the DMAPMA comonomer, nanogels are quaternized with a 1-bromo-dodecane chain via an N-alkylation reaction. The alkylation introduces the antibacterial activity due to the bacterial membrane binding and the intercalating ability of the aliphatic QAC. Subsequently, the quaternized nanogels enable the formation of intraparticle hydrophobic domains because of intraparticle hydrophobic interactions of the aliphatic chains allowing for Triclosan incorporation. The coating with Triclosan-loaded nanogels shows a killing efficacy of up to 99.99% of adhering bacteria on the surface compared to nonquaternized nanogel coatings while still possessing an antifouling activity. This powerful multifunctional coating for combating biomaterial-associated infection is envisioned to greatly impact the design approaches for future clinically applied coatings.