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Schiff base hydrogels have attracted much attention in recent years in the field of biomedical applications, due to the reversibility of the imine bond, granting the gels degradation properties. Commonly used multifunctional amines include proteins and polysaccharides like bovine serum albumin and chitosan, that exhibit low water solubility. One of the most commonly used dialdehydes, utilized for Schiff base formation, is glutaric aldehyde, that is known to be toxic. We are presenting a new two component Schiff-base-crosslinked hydrogel based on an aminoterminated hyperbranched polyglycerol (hPG-NH2) and a polyethyleneglycol dialdehyde (PEG-DA), that shows promising mechanical properties. The hPG-NH2 is synthesized by a photoinitiated thiolene coupling reaction, following a previously established copolymerization of glycidol and allyl glycidyl ether. The PEG-DA was synthesized in a one-pot synthesis, by the addition of isophorone diisocyanate (IPDI) and hydroxymethylfurfural (HMF). The hydrogels were characterized regarding their mechanical properties with a texture analyzer. With this method, the impact of the solid content, the ratio of the components and the pH on the gel properties was studied.

Aqueous processes yielding hybrid or composite materials are widespread in natural environments and their control is fundamental for a multiplicity of living organisms. Their design and in vitro engineering require knowledge about the spatiotemporal evolution of the interactions between the involved liquid and solid phases and, especially, the interphases governing the development of adhesion during solidification. The present study illustrates the effects of distinct proteins on the precipitation of sodium chloride encompassing the size, shape and distribution of halite crystals formed during the drying of droplets containing equally concentrated saline protein solutions. The precipitates obtained from aqueous sodium chloride formulations buffered with tris(hydroxymethyl)aminomethane (Tris) contained either bovine serum albumin (BSA), fibrinogen or collagen and were characterized with respect to their structure and composition using optical and electron microscopy as well as x-ray analysis. The acquired findings highlight that depending on the protein type present during droplet drying the halite deposits predominantly exhibit cubic or polycrystalline dendritic structures. Based on the phenomenological findings, it is suggested that the formation of the interphase between the growing salt phase and the highly viscous saline aqueous jelly phase containing protein governs not only the material transport in the liquid but also the material exchange between the solid and liquid phases.

Although alginate-based hydrogels are widely used, determining their mechanical properties and explaining their ability to form a hydrogel in situ remains a challenge. A new method of external gelation using calcium chloride (CaCl2) is proposed to quantify the formation of alginate hydrogel and its mechanical properties as well as to observe its temporal behaviour. To this end, small inhomogeneous alginate beads were formed, which comprised a shell and a core. The bead’s shell consisted of calcium alginate hydrogel, while its core was sodium alginate sol. The beads were mechanically tested with a texture analyser to provide a detailed description of the structure. Different alginate samples could be clearly identified, and the M(mannuron)/G(guluron) acid ratios could be extrapolated quickly and easily from the test results if calibrated by NMR. This enables a fast and cost-effective characterisation of different alginates with regard to their composition and gel formation properties.

Biofouling is a major challenge in the application of textiles, biosensors, and biomedical implants. In the current work, a straightforward method for the solvent-free polymerization of antifouling dendritic polyglycerol (dPG) from mussel-inspired dendritic polyglycerol (MI-dPG) coatings on hydrophilic titanium dioxide (TiO2) and hydrophobic polydimethylsiloxane (PDMS) is reported. Surface characterization is performed by static water contact angle (CA) measurements, X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM). Significant lower CA values are obtained after dPG grafting from MI-dPG-coated TiO2 and MI-dPG coated PDMS. Furthermore, XPS shows a time-dependent increase of the CO bond content upon dPG grafting from MI-dPG-coated TiO2 and MI-dPG-coated PDMS. Analysis of the surface morphology by SEM shows a clear time-dependent increase in the surface roughness upon dPG grafting from MI-dPG-coated TiO2 and MI-dPG-coated PDMS. When the viability of two adhesive cell types is studied via LIVE/DEAD staining, a strong reduction in the cell density is observed after the dPG grafting from MI-dPG-coated TiO2 and MI-dPG-coated PDMS (a decrease of >95% in all cases). The combined results show that biocompatible but highly cell-repelling surfaces are efficiently constructed via the grafting of dPG from MI-dPG-coated TiO2 and MI-dPG-coated PDMS.

The development of new bone adhesives is severely restricted due to the lack of a standard test method to examine their bond strength. Therefore, this study presents an in vitro bone-to-bone adhesion test method based on a compression shear test using cortical bone specimens (35 × 15 × 3 mm). The zero-gap lap joint test configuration was used to measure the bonding strengths of two soft tissue adhesives (Histoacryl® and BSA-Glue) and a bone cement (Palacos® LV). For reproducible bonding results, it is crucial to work with specimen having reproducible surface, dimensions and where and how they were taken from a bone. Therefore, this is a focus of the work. The adhesive strengths were determined under dry and physiological conditions to evaluate the reliability of the test procedure. Furthermore, the influence of previous acid etching of the bone surface was also investigated. The adhesives achieved bond strengths of 5.5 MPa (Histoacryl®), 3.2 MPa (BSA-Glue) and 2.8 MPa (Palacos® LV) under dry conditions. Under physiological conditions, the measured adhesive strengths of all three bonding materials decreased by around 90%. The acid etching led to a higher presence of reactive amino groups on the bone surface and improved the adhesion of Histoacryl® and BSA-Glue. The Palacos® LV bone cement suffered a reduction in adhesion as the acid smoothened the bone surface, resulting in less mechanical interlocking. The proposed test method is based on known standards and enables the usability of medical adhesives as a bone adhesive to be evaluated in a reproducible manner.

To evaluate a recently reported new bioadhesive system for the retrieval of small residual fragments (RFs) after intracorporeal lithotripsy, we systematically compared this system with coagulum lithotomy in retrograde intrarenal surgery.We extracted 30 human stone fragments (≤1 mm) in an ex vivo porcine kidney model using a flexible ureteroscope for three groups: (1) the novel bioadhesive, (2) autologous blood as a natural adhesive, and (3) (control group) a conventional retrieval basket. Each group consisted of 15 test runs. Outcomes were evaluated regarding the macroscopic stone-free rate (SFR), retrieval time, and number of ureteral passages.For groups 1 and 2, a significant advantage in stone clearance, mean retrieval time, and number of retrievals was detected compared to the control group (p = 0.001). The time and number of retrievals were significantly lower in group 1 (10:36 minutes, p = 0.001) than in group 2 (26:12 minutes, p = 0.001), with shorter clotting time and better visibility.These data show the general feasibility of intrarenal RF embedding to improve the SFR. Our data furthermore suggest the superiority of the artificial bioadhesive embedding agent over the application of native blood. Further in vivo studies and other research are necessary to confirm the adhesive's effect in patients.

Aim of this investigation was to demonstrate in laboratory and field experiments, the ability of relevantly selected non-ionic surfactant, non-toxic antioxidant and their combinations to reduce sharply marine biofilm development on polysiloxane coatings totally preventing marine macro-fouling on slowly moving and static immersed surfaces. Their superior antifouling properties: reduced to zero mussel and algae adhesion, as well as multispecies macro-fouling, and 6–10 folds reduced marine biofilm, were attributed to a formation of a thin, plane, “bioactive” surface layer. Its excellent anti-biofouling action was supposed to be due to the presence of impeding the initial microbial attachment non-ionic surfactant that together with the non-toxic antioxidant inhibits a supposed oxidative cross-linking of secreted exopolymeric substances and later assists the biofilm dispersal.

The present study reports for the first time the presence of giant crystals in mitochondria of equine chondrocytes. These structures show dark contrast in TEM images as well as a granular substructure of regularly aligned 1–2 nm small units. Different zone axes of the crystalline structure were analysed by means of Fourier transformation of lattice-resolution TEM images proving the crystalline nature of the structure. Elemental analysis reveals a high content of nitrogen referring to protein. The outer shape of the crystals is geometrical with an up to hexagonal profile in cross sections. It is elongated, spanning a length of several micrometres through the whole cell. In some chondrocytes, several crystals were found, sometimes combined in a single mitochondrion. Crystals were preferentially aligned along the long axis of the cells, thus appearing in the same orientation as the chondrocytes in the tissue. Although no similar structures have been found in the cartilage of any other species investigated, they have been found in cartilage repair tissue formed within a mechanically stimulated equine chondrocyte construct. Crystals were mainly located in superficial regions of cartilage, especially in joint regions of well-developed superficial layers, more often in yearlings than in adult horses. These results indicate that intramitochondrial crystals are related to the high mechanical stress in the horse joint and potentially also to the increased metabolic activity of immature individuals. Electronic supplementary material The online version of this article (doi:10.1007/s00418-016-1516-6) contains supplementary material, which is available to authorized users.

Residual fragments related to endoscopic intracorporeal lithotripsy are a challenging problem. The impact of residual fragments remains a subject of discussion and growing evidence highlights that they have a central role in recurrent stone formation. Therefore, we developed a novel bioadhesive system for intrarenal embedding and retrieval of residual fragments after endoscopic lithotripsy in an ex vivo porcine kidney model.In a standardized setting 30 human stone fragments 1 mm or less were inserted in the lower pole of an ex vivo porcine kidney model. We assessed the extraction efficacy of flexible ureteroscopy using the bioadhesive system in 15 preparations and a conventional retrieval basket in 15. Outcomes were compared regarding the endoscopic and macroscopic stone-free rate, and overall time of retrieval.Embedding and retrieving the residual fragment-bioadhesive complex were feasible in all trial runs. We observed no adverse effects such as adhesions between the adhesive and the renal collecting system or the instruments used. The stone-free rate was 100% and 60% in the bioadhesive and conventional retrieval groups, respectively (p = 0.017). Mean retrieval time was significantly shorter at 10 minutes 33 seconds vs 36 minutes 56 seconds in the bioadhesive group vs the conventional group (p = 0.001).This novel method involving adhesive based complete removal of residual fragments from the collecting system has proved to be feasible. Our evaluation in a porcine kidney model revealed that this technology performed well. Further tests, including inpatient studies, are required to thoroughly evaluate the benefit and potential drawbacks of bioadhesive based extraction of residual fragments after intracorporeal lithotripsy.

Adhesives are not only being used increasingly in the design of medical devices, but also in the field of application, both directly on and in humans, for example as a replacement for the suturing and stapling of tissue through adhesive bonding. The advantages of using adhesives include less tissue damage, no incorporated materials that require removal, and a better biocompatibility. In this context, adhesives in the broader sense also perform functions that conventional methods cannot, for example as sealants or blood hemostats. In addition to fully synthetic and semi-synthetic adhesives, an increasing number of formulations are finding their way into research as well as clinical trials or clinical applications that are based on concepts taken from nature (biomimetic) or are a combination of biological and chemical components or are of completely biological origin. The importance of medical adhesives is evident not only in the almost double-digit annual growth rates, but also in the number of publications in this field. The constantly increasing requirements for the approval (CE marking in the EU, 510k or PMA in the USA) of new adhesives (fully synthetic, semi-synthetic, or biological) and the development of such systems in accordance with these requirements and those of the user (medical practitioners) still represent major challenges. This is partly due to the fact that development scenarios, such as the technology-push and market-pull approaches, are currently not being applied in a holistic and interdisciplinary manner.

Peptides and proteins have been largely neglected in the analysis of insect tarsal adhesives. After extraction of the protein fraction of the tarsal secretion of the desert locust, Schistocerca gregaria, and Madagascar hissing cockroach, Gromphadorhina portentosa, we combined Fourier transform infrared spectroscopy (FTIR), sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) and matrix-assisted laser desorption/ionization mass spectrometry (MALDI-TOF MS) analyses for protein mass detection. In both these insects, SDS-PAGE analysis revealed several protein bands ranging from 8-190 kDa in both the tarsal secretion and the tibia control sample. Two (S. gregaria) and one (G. portentosa) protein bands exclusively occurred in the tarsal secretion and can be considered to belong to peptides and proteins specific to this secretion. MALDI-TOF analyses revealed 83 different proteins/peptides of 1-7 kDa in S. gregaria, and 48 of 1-11 kDa in G. portentosa. 59 (S. gregaria) and 27 (G. portentosa) proteins exclusively occurred in the tarsal secretion. In G. portentosa, a characteristic series of signal peaks occurred in the range of c. 10-12 kDa, each peak being approximately 160 Da apart. Such a pattern is indicative of proteins modified by glycosylation. Our approach demonstrates that extensive sampling involving considerable time and manpower to sample the adhesive fluid directly from the tarsi opens up a perspective for extracting peptides and proteins in sufficient quantities. This makes them accessible to the field of proteomics and thus to elucidate their possible function in the adhesive process.

Die gestielte Meereichel Dosima fascicularis nutzt ein Flos aus einem schaumartigen Proteinhydrogel zum Uberleben. Das Gel ware aufgrund seines Aufbaus und der Zusammensetzung ein idealer Klebstoff fur die Medizin.

Continuous‐flow ventricular assist devices (VADs) have established themselves as a lifesaving therapy option in patients with severe cardiovascular disease. Unfortunately, complications with VADs resulting from the shear‐induced formation of surface blood clots are common. In the current work, an antifouling coating based on the combination of mussel‐inspired dendritic polyglycerol (MI‐dPG) and linear polyglycerol (lPG) is tested for its cell‐repelling properties, biocompatibility, and complement activating properties. Furthermore, the adhesion and activation of blood platelets are tested under static and flow conditions. The adhesion and proliferation of two cell types are studied by means of LIVE/DEAD cell staining, and it is clearly observed that the lPG‐functionalized MI‐dPG coating prevents cell adhesion. Additionally, no cell mortality is observed on all substrates, indicating the biocompatibility of the tested coatings. All coatings show lower (or equal) complement‐activating properties than bare titanium, which is considered a highly biocompatible material. Most importantly, the lPG‐functionalized system prevents the adhesion and activation of blood platelets under static and flow conditions. Finally, a prototype VAD is successfully coated with MI‐dPG under flow conditions. In the current study, the efficient lPG‐functionalization of the MI‐dPG coating is proved to obtain cell‐ and platelet‐repelling surfaces.

This work describes the fabrication and evaluation of a transparent hydrogel based spray coating to reduce marine biofouling on glass surfaces. A glycerol based copolymer was synthesized and covalently immobilized by applying a simple spray coating procedure. To test its nonfouling behavior, modified glass surfaces were exposed to different marine fouling species including bacteria, green algae, and blue mussels. For all tested species the coating could considerably reduce the settlement as compared to pristine glass surfaces. The settlement of blue mussels on coated surfaces was additionally compared to polytetrafluoroethylene (PTFE) substrates. The glycerol based copolymer showed an even better resistance against blue mussel adhesion than PTFE. Furthermore, the nonfouling performance of the coating was tested via fibrinogen adsorption after aging coated silica slides under marine conditions. The major aim of this study is to provide an easy synthesis and application procedure for a polyglycerol based nonfouling coating and the evaluation of its nonfouling properties in marine environments.

Bacterial adhesion to the surface of implants in bone tissue may result in serious peri-implant diseases and cannot always be avoided by sterilization prior to implantation. For this reason, different strategies to confer the implant surfaces with intrinsic antibacterial properties are being developed. A major difficulty is that effective antibacterial materials may be detrimental to the adhesion of eukaryotic cells, and be poorly integrated into the host tissue. Here, we develop and characterize a composite coating material comprising silver nanoparticles deeply buried inside a matrix of plasma-polymerized hexamethyldisiloxane. Applied to titanium dental screws, the coating shows a good resistance against stresses from sterilization with β-irradiation and drilling into bone tissue. By varying the parameters of the plasma-depositing process, we are able to either induce or hinder the adhesion of epithelial cells. Through a fluorescence microscopy analysis, we demonstrate that the inclusion of silver nanoparticles in the polymer matrix does not influence the adhesion of fibroblasts and osteoblasts. However, the presence of silver in the coating layer results in dramatically reduced adhesion of Escherichia coli bacteria with respect to uncoated or silver-free coated surfaces.

Salamanders have evolved a wide variety of antipredator mechanisms and behavior patterns, including toxins and noxious or adhesive skin secretions. The high bonding strength of the natural bioadhesives makes these substances interesting for biomimetic research and applications in industrial and medical sectors. Secretions of toxic species may help to understand the direct effect of harmful substances on the cellular level. In the present study, the biocompatibility of adhesive secretions from four salamander species (Plethodon shermani, Plethodon glutinosus, Ambystoma maculatum, Ambystoma opacum) were analyzed using the MTT assay in cell culture and evaluated against toxic secretions of Pleurodeles waltl, Triturus carnifex, Pseudotriton ruber, Tylototriton verrucosus, and Salamandra salamandra. Their effect on cells was tested in direct contact (direct culture) or under the influence of the extract (indirect exposure) in accordance with the protocol of the international standard norm ISO 10993-5. Human dermal fibroblasts (NHDF), umbilical vein endothelial cells (HUVEC), and articular chondrocytes (HAC), as well as the cell lines C2C12 and L929 were used in both culture types. While the adhesive secretions from Plethodon shermani are cytocompatible and those of Ambystoma opacum are even advantageous, those of Plethodon glutinosus and Ambystoma maculatum appear to be cytotoxic to NDHF and HUVEC. Toxic secretions from Salamandra salamandra exhibited harmful effects on all cell types. Pseudotriton ruber and Triturus carnifex secretions affected certain cell types marginally; those from Pleurodeles waltl and Tylototriton verrucosus were generally well tolerated. The study shows for the first time the effect of salamander secretions on the viability of different cell types in culture. Two adhesive secretions appeared to be cell compatible and are therefore promising candidates for future investigations in the field of medical bioadhesives. Among the toxic secretions tested, only two of the five had a harmful effect on cells, indicating different cell toxicity mechanisms.

A set of new catecholic monolayer coatings was developed to improve the antifouling performance of TiO2 surfaces. To solve the problem of the weak charge-transfer interaction between a single catechol anchor and TiO2, multiple catechol groups were combined with hyperbranched polyglycerol (hPG) which is a distinct dendritic scaffold that exposes its multivalent anchor groups on the surface. Thus, multivalent catecholic hPGs can be easily prepared for surface modification. The immobilization of the compounds was monitored by quartz crystal microbalance with dissipation monitoring. Surface properties of the coatings were analyzed by water contact angle, X-ray photoelectron spectroscopy, and atomic force microscopy. The antifouling ability and stability were investigated by protein adsorption and cell adhesion. By increasing the number of catechol groups on the hPG scaffold, the stability and surface coverage could be significantly enhanced. Moreover, the inner-layer crosslinking of the coatings by grafting and initiating vinyl groups clearly improved their long-term stability. As a result, hPG with a catecholic functional degree of 10% (hPG-Cat10) and hPG with both catecholic and vinylic functional degree of 5% (hPG-Cat5-V5) were identified as the best catecholic hPGs to prepare bioinert and stable monolayer coatings on TiO2.

The goose barnacle Dosima fascicularis produces an excessive amount of adhesive (cement), which has a double function, being used for attachment to various substrata and also as a float (buoy). This paper focuses on the chemical composition of the cement, which has a water content of 92%. Scanning electron microscopy with EDX was used to measure the organic elements C, O and N in the foam-like cement. Vibrational spectroscopy (FTIR, Raman) provided further information about the overall secondary structure, which tended towards a β-sheet. Disulphide bonds could not be detected by Raman spectroscopy. The cystine, methionine, histidine and tryptophan contents were each below 1% in the cement. Analyses of the cement revealed a protein content of 84% and a total carbohydrate content of 1.5% in the dry cement. The amino acid composition, 1D/2D-PAGE and MS/MS sequence analysis revealed a de novo set of peptides/proteins with low homologies with other proteins such as the barnacle cement proteins, largely with an acidic pI between 3.5 and 6.0. The biochemical composition of the cement of D. fascicularis is similar to that of other barnacles, but it shows interesting variations.

In this work, we combine nature's amazing bioadhesive catechol with the excellent bioinert synthetic macromolecule hyperbranched polyglycerol (hPG) to prepare antifouling surfaces. hPG can be functionalized by different amounts of catechol groups for multivalent anchoring and cross-linking because of its highly branched architecture. The catecholic hPGs can be immobilized on various surfaces including metal oxides, noble metals, ceramics, and polymers via simple incubation procedures. The effect of the catechol amount on the immobilization, surface morphology, stability, and antifouling performance of the coatings was studied. Both anchoring and cross-linking interactions provided by catechols can enhance the stability of the coatings. When the catechol groups on the hPG are underrepresented, the tethering of the coating is not effective; while an overrepresentation of catechol groups leads to protein adsorption and cell adhesion. Thus, only a well-balanced amount of catechols as optimized and described in this work can supply the coatings with both good stability and antifouling ability.

We introduce a novel technique for an initial identification of peptide sequences that specifically bind to material surfaces based on the matrix assisted laser desorption ionization time of flight mass spectrometry (MALDI-ToF MS) depletion method. The technique relies upon time-resolved, sensitive measurements of the MALDI-ToF MS peak signals acquired from a solution containing several peptides placed in contact with an inorganic surface, in our case amorphous SiO2. Large errors intrinsic in the MALDI-ToF MS spectral analysis and uncertainties arising from the adsorption behaviour of peptide mixtures limit the predictive power of the method. However, when combined with other characterisation and modelling techniques, such as High-Performance Liquid Chromatography (HPLC), Atomic Force Microscopy (AFM), Quartz Crystal Microbalance with Dissipation (QCM-D) and Molecular Dynamics (MD), it can be used as a guide to identify novel material-binding peptide sequences, such as TPGSR for SiO2. The strategy presented in this work may have an impact on the design and synthesis of novel hybrid biomaterials based on the biomolecular recognition of inorganic surfaces.

Implant-associated infections represent a serious risk in human medicine and can lead to complications, revisions and in worst cases, amputations. To target these risks, the objective was to design a hybrid implant surface that allows a local burst release of antibiotics combined with long-term antimicrobial activity based on silver. The efficacy should be generated with simultaneous in vitro cytocompatibility. The investigations were performed on titanium K-wires and plates and gentamicin was selected as an illustrative antibiotic. A gentamicin depot (max 553 &micro, g/cm2) was created on the surface using laser structuring. The antibiotic was released within 15 min in phosphate buffered saline (PBS) or agar medium. Metallic silver particles (4 &micro, g/cm2) in a titanium dioxide layer were deposited using plasma vapor deposition (PVD). About 16% of the silver was released within 28 days in the agar medium. The local efficacy of the incorporated silver was demonstrated in a direct contact assay with a reduction of more than 99.99% (Escherichia coli). The local efficacy of the hybrid surface was confirmed in a zone of inhibition (ZOI) assay using Staphylococcus cohnii. The biocompatibility of the hybrid surface was proven using fibroblasts and osteoblasts as cell systems. The hybrid surface design seems to be promising as treatment of implant-associated infections, considering the achieved amount and release behavior of the active ingredients (gentamicin, silver). The generated in vitro results (efficacy, biocompatibility) proofed the concept. Further in vivo studies will be necessary translate the hybrid surface towards clinical applied research.

This article describes a new strategy for coupling the enzyme horseradish peroxidase to a two-component polyurethane (2C-PUR) coating. A stable polymer conjugate was achieved by combining the enzyme and the 2C-PUR coating which was modified with poly(dimethylsiloxane) (PDMS), located at the surface. An atmospheric pressure plasma jet system was used to convert alkyl groups from the PDMS into polar silanol functionalities. This conversion was proven by X-ray photoelectron spectroscopy and dynamic contact angle measurements. In addition, the stability of the activated 2C-PUR surface containing silanol groups was determined by measuring the contact angle as a function of time. Compared to the non-modified 2C-PUR systems the one with PDMS displayed a higher stability over a time period over 28 h. In a silanization process the coating was treated with (3-aminopropyl) trimethoxysilane and the enzyme was subsequently immobilized to the coating via the cross linker glutaraldehyde to receive new biomimetic catalytic/enzymatic functions. The chemical immobilization (chemisorption) of the enzyme to the surface showed statistically significant higher biological activity as compared to references samples without using a cross linker (physisorption). The presented technique offers the opportunity to design new and smart multifunctional surface coatings which employ biomimetic capabilities.

Antifreeze proteins (AFPs) are of great importance for applications in cryomedicine or the food industry. They are frequently used to lower the freezing point by preventing the growth of larger ice crystals; thus, it is paramount to determine their thermal hysteretic characteristics. However, the experimental analysis of the thermal hysteresis-an effect that is characteristic for AFPs-remains a challenging process. An easy-to-use test method for measuring the thermal hysteresis of AFPs was developed and tested with the type III AFPs. Traditional methods that have been used until now have their disadvantages and limitations. The new measurement method described in this paper allows detection of the complete cooling, freezing, heating, and melting process in a single measurement. This makes it possible to directly determine the thermal hysteresis as a functional effect of the antifreeze proteins. Measurements of the thermal hysteresis were performed by applying ultrasound to initiate the crystallization process of the antifreeze protein solution. This ultrasound technique also allows a crystallization process to be performed at defined temperature. The demonstrated results were highly reproducible and could be clearly read off the measurement curves. As a future perspective, this enables the design of automatic test devices that can be also miniaturized.

Barnacles produce a proteinaceous adhesive called cement to attach permanently to rocks or to other hard substrata. The stalked barnacle Dosima fascicularis is of special interest as it produces a large amount of foam-like cement that can be used as a float. The morphology of the cement apparatus and of the polymerized cement of this species is almost unknown. The current study aims at filling these gaps in our knowledge using light and electron microscopy as well as x-ray microtomography. The shape of the cement gland cells changes from round to ovoid during barnacle development. The cytoplasm of the gland cells, unlike that of some other barnacles, does not have distinct secretory and storage regions. The cement canals, which transport the cement from the gland cells to the base of the stalk, end at different positions in juvenile and mature animals. With increasing size of the cement float, the exit of the cement canals shift from the centrally positioned attachment disk of the vestigial antennules to more lateral positions on the stalk. The bubbles enclosed in the foam-like float are most likely filled with CO(2) that diffuses from the hemolymph into the cement canal system and from there into the cement.

Nautiloidea is the oldest group within the cephalopoda, and modern Nautilus differs much in its outer morphology from all other recent species; its external shell and pinhole camera eye are the most prominent distinguishing characters. A further unique feature of Nautilus within the cephalopods is the lack of suckers or hooks on the tentacles. Instead, the animals use adhesive structures present on the digital tentacles. Earlier studies focused on the general tentacle morphology and put little attention on the adhesive gland system. Our results show that the epithelial parts on the oral adhesive ridge contain three secretory cell types (columnar, goblet, and cell type 1) that differ in shape and granule size. In the non-adhesive aboral epithelium, two glandular cell types (cell types 2 and 3) are present; these were not mentioned in any earlier study and differ from the cells in the adhesive area. The secretory material of all glandular cell types consists mainly of neutral mucopolysaccharide units, whereas one cell type in the non-adhesive epithelium also reacts positive for acidic mucopolysaccharides. The present data indicate that the glue in Nautilus consists mainly of neutral mucopolysaccharides. The glue seems to be a viscous carbohydrate gel, as known from another cephalopod species. De-attachment is apparently effectuated mechanically, i.e., by muscle contraction of the adhesive ridges and tentacle retraction.

To evaluate the viability and biocompatibility of a novel, patented bioadhesive system for intrarenal embedding and retrieval of residual fragments after endoscopic lithotripsy. Complete stone clearance via active removal of residual fragments (RF) after intracorporeal laser lithotripsy may be time-consuming and fail in many cases. Therefore, the novel adhesive has been developed and evaluated for the first time in an in vivo pig model in the present work. Four female domestic pigs underwent flexible ureteroscopy (RIRS) or percutaneous nephrolithotomy (PNL) under general anesthesia (8 kidneys, 4 × RIRS, 4 × PNL) evaluating the bioadhesive system. Interventions: RIRS without adhesive system (sham procedure, kidney I); 3 × RIRS using the bioadhesive system (kidneys II–IV); and 4 × PNL using the bioadhesive system (V–VIII). We endoscopically inserted standardized human stone probes followed by comminution using Ho:YAG lithotripsy. The bioadhesive (kidney II–VIII) was then applied and the adhesive-stone fragment complex extracted. After nephrectomy, all kidneys were evaluated by two independent, blinded pathologists. Endpoints were the procedure’s safety and adhesive system’s biocompatibility. We observed no substantial toxic effects. We were able to embed and remove 80–90% of fragments. However, because of the pig’s hampering pyelocaliceal anatomy, a quantified, proportional assessment of the embedded fragments was compromised. For the first time, we demonstrated the proven feasibility and safety of this novel bioadhesive system for embedding and endoscopically removing small RF in conjunction with a lack of organ toxicity in vivo.

Siloxane fouling release coatings are currently the only viable non-toxic commercial alternative to toxic biocide antifouling paints. However, they only partially inhibit biofouling since biofilms remain a major issue. With the aim to improve the bacterial resistance of siloxane coatings modified with non-ionic surfactant (NIS), antioxidant (AO) or both NIS/AO, the ability of PEG-silane co-cross-linker was investigated to reduce Cobetia marina adhesion and multispecies biofilm formation from natural seawater. Surface physical-chemical and physical-mechanical parameters relevant to bio-adhesion were estimated before the testing of the biofilm formation. Slightly reduced biofilm from C. marina and sharply reduced multispecies biofilm, formed in natural sea water, were found on the PEG-silane co-cross-linked coatings without modifying additives. However, both C. marina growth and biofilm formation from natural sea water were sharply reduced on the PEG-silane co-cross-linked coatings containing NIS or AO, even more, no C. marina adhesion was seen on the coating containing NIS and AO simultaneously. Possible explanations of the observed effects are presented in this article. It was concluded that the PEG-silane co-cross-linker, toghether with NIS and AO, can be used as an efficient tool to additionally reduce the bioadhesion of Gram-negative marine bacteria and multispecies biofilm formation on siloxane antifouling coatings.

Proteins are ubiquitous biopolymers that adopt distinct three-dimensional structures and fulfil a multitude of elementary functions in organisms. Recent systematic studies in molecular biology and biotechnology have improved the understanding of basic functional and architectural principles of proteins, making them attractive candidates as concept generators for technological development in material science, particularly in biomedicine and nano(bio)technology. This paper highlights the potential of molecular biomimetics in mimicking high-performance proteins and provides concepts for applications in four case studies, i.e. spider silk, antifreeze proteins, blue mussel adhesive proteins and viral ion channels.

The inflammatory and proapoptotic cytokine TNF possesses a compelling potential as an antitumoral therapeutic agent. Possible target cells include the malignant cells themselves, the tumor vasculature, or the immune system. As the clinical use of TNF is limited by systemic toxicity, targeting strategies using TNF-based fusion proteins are currently used. A major obstacle, however, is that homotrimeric TNF ligands are prone to activity loss due to dissociation into their monomers. In this study, we report the construction of single-chain TNF molecule, a TNF mutant consisting of three TNF monomers fused by short peptide linkers. In comparison to wild-type TNF, single-chain TNF was found to possess increased stability in vitro and in vivo, displayed reduced systemic toxicity yet slightly enhanced antitumoral activity in mouse models. Creation of single-chain variants is a new approach for improvement of functional activity of therapeutics based on TNF family ligands.

Amphibians have evolved a wide variety of mechanisms that provide a certain degree of protection against predators, including camouflage, tail autonomy, encounter behavior and noxious or toxic skin secretions. In addition to these strategies, some amphibians release a glue-like secretion onto the surface of their skin when threatened. While some information regarding the origin and production of these adhesive secretions is available for frogs such as Notaden bennetti, these aspects are only partially understood in salamanders. We contribute to an earlier study and provide additional information regarding the origin, production, and characterization of the adhesive secretion in the red-legged salamander (Plethodon shermani) at a microanatomical level. When stressed, this salamander secretes a milky, viscous liquid from its dorsal and ventral skin. This secretion is extremely adhesive and hardens within seconds upon exposure to air. This study describes two cutaneous gland types (mucous and granular) in the dorsal and ventral epithelial tissue that differ considerably in their secretory content. While the smaller mucous glands contains flocculent to granular material, mostly acidic glycoproteins, the granular glands synthesize various granules of differing size and density that consist of basic proteinaceous material. The results strongly indicate that the secretions of both gland types from the dorsal as well as the ventral side form the adhesive mucus in Plethodon shermani, consisting of basic and acidic glycoproteins, glycoconjugates with mannose and alpha-L-fucose residues as well as lipid components. (C) 2015 Elsevier GmbH. All rights reserved.

The results of the first chemical analysis of the adhesive of Lepas anatifera , a stalked barnacle, are presented. A variety of elements were identified in scanning electron microscopy with energy dispersive spectrometry (SEM-EDS) of the adhesive, including Na, Mg, Ca, Cl, S, Al, Si, K and Fe; however, protein–metal interactions were not detected in Raman spectra of the adhesive. Elemental signatures from SEM-EDS of L. anatifera adhesive glands were less varied. Phosphorous was mostly absent in adhesive samples; supporting previous studies showing that phosphoserines do not play a significant role in adult barnacle adhesion. Disulfide bridges arising from Cys dimers were also investigated; Raman analysis showed weak evidence for S–S bonds in L. anatifera . In addition, there was no calcium carbonate signal in the attenuated total reflectance Fourier transform infrared spectra of L. anatifera adhesive, unlike several previous studies in other barnacle species. Significant differences were observed between the Raman spectra of L. anatifera and Balanus crenatus ; these and a range of Raman peaks in the L. anatifera adhesive are discussed. Polysaccharide was detected in L. anatifera adhesive but the significance of this awaits further experiments. The results demonstrate some of the diversity within barnacle species in the chemistry of their adhesives.

The main driving force behind water transport in plants is the air's low water potential. In the presence of high humidity, the transpiration process is halted and water transport is mainly sustained by the root pressure. The surplus of water following the removal of essential components (e.g. salts) is excreted by the plant via guttation through the hydathodes. When guttation occurs, the plant surface is wetted. These are the conditions that will allow epiphytic living, motile bacteria to move and to eventually enter the plant's interior via the hydathodes. The question arose as to whether the plant has developed a protection mechanism against motile bacteria in the vicinity of the hydathodes. Such a protection mechanism could use the well known pathogenesis-related (PR) proteins. Indeed, an analysis of the guttation fluid using one- and two-dimensional electrophoresis showed a clustering of approximately 200 proteins, primarily with isoelectric points in the acidic pH. Proteins identified using electrospray ionization mass spectroscopic analysis and western blot analysis belong mostly to the family of PR-proteins suggesting a role in plant protection against invaders. The protein profile of the guttation fluid was remarkably modified by treating plants with methyl jasmonic acid suggesting that the protein composition of the guttation fluid is controlled by internal and/or external stimuli.

A rapid and universal approach for multifunctional material coatings was developed based on a mussel-inspired dendritic polymer. This new kind of polymer mimics not only the functional groups of mussel foot proteins (mfps) but also their molecular weight and molecular structure. The large number of catechol and amine groups set the basis for heteromultivalent anchoring and crosslinking. The molecular weight reaches 10 kDa, which is similar to the most adhesive mussel foot protein mfp-5. Also, the dendritic structure exposes its functional groups on the surface like the folded proteins. As a result, a very stable coating can be prepared on virtually any type of material surface within 10 min by a simple dip-coating method, which is as fast as the formation of mussel byssal threads in nature.

A new coupling strategy for biomacromolecules with (3-mercaptopropyl)trimethoxysilane (3MPTMS) and 11-(triethoxysilyl)undecanal (TESU) on gold surfaces is. This immobilization protocol was utilized for the enzyme horseradish peroxidase (HRP). To study the reactions and resulting structures, PM-IRRAS measurements were performed. PM-IRRAS shows there is structure preservation of the HRP when the new coupling strategy is used in contrast to non-specific adsorption on gold. The biological activity of adsorbed and immobilized HRP was measured by the enzyme catalyzed oxidation of 3,5,3',5'-tetramethylbenzidine. Covalent immobilization of HRP on TESU film compared to physisorption of HRP shows higher enzyme activity on gold surfaces, confirming the structural preservation detected by PM-IRRAS.

Material-independent and bioinert hierarchical polymer multilayer coatings are presented. Chemically active catecholic hyperbranched polyglycerols (hPGs) form a foundation layer on a versatile surface via multivalent anchoring and crosslinking, the activity of which is shielded by the bioinert catecholic hPGs. Mono-catecholic hPGs finally terminate all of the free catechols to build a flexible bioinert top layer. These coatings perfectly prevent protein and cell adhesion.

The influence of adhesion on molecular conformations—besides solely molecule orientation—and vice versa was rarely considered in adhesion science due to the difficult analysis of conformational equilibria, in general, and the high number of possible conformations in classical polymers, in particular. Fortunately, some insight is available from the interphase chemistry of proteins due to the importance regarding their biological function in heterogeneous systems. Peptides and proteins are, thus, ideal model systems for the experimental and theoretical investigation of conformational changes in interphases. The conformational equilibrium of any kind of compound or, more specifically, a polymer interacting with a surface must differ in the interphase when compared with the bulk. This is also the case for common adhesives. Therefore, we define that the interphase of an adhesive bond is the area in which the chemical composition or the conformational equilibrium differs from that of the bulk phase.

Adhesion in cephalopods is either mechanical, involving a reduced-pressure system of the arm and tentacle suckers, or is chemically mediated by special adhesive gland structures (as proposed for Euprymna, Idiosepius, and Nautilus). Four species of Sepia (S. typica, S. papillata, S. pulchra, and S. tuberculata) possess grooved structures on the ventral mantle surface and on the fourth arm pair, which are used to attach mechanically to the substratum. Because these areas are often partly covered with sand or debris, it has been hypothesized that chemical substances were involved in this attachment process. This study provides a histochemical and ultrastructural description of the glandular epithelium in the adhesive area of Sepia tuberculata. Two specific glandular cells (Type 1 and Type 2) are present in the epithelium, which differ clearly in their granule size and cellular structure. The aggregation of both cell types and their simultaneous secretion suggest that the secretions of both cell types work synergistically providing a two-component adhesive system which supports the primarily mechanical sucker adhesion by making the arm surface sticky. J. Morphol. 2011. © 2011 Wiley-Liss, Inc.

The work described in this paper demonstrates that very small protein and DNA structures can be applied to various substrates without denaturation using aerosol printing technology. This technology allows high-resolution deposition of various nanoscaled metal and biological suspensions. Before printing, metal and biological suspensions were formulated and then nebulized to form an aerosol which is aerodynamically focused on the printing module of the system in order to achieve precise structuring of the nanoscale material on a substrate. In this way, it is possible to focus the aerosol stream at a distance of about 5 mm from the printhead to the surface. This technology is useful for printing fluorescence-marked proteins and printing enzymes without affecting their biological activity. Furthermore, higher molecular weight DNA can be printed without shearing. The advantages, such as printing on complex, non-planar 3D structured surfaces, and disadvantages of the aerosol printing technology are also discussed and are compared with other printing technologies. In addition, miniaturized sensor structures with line thicknesses in the range of a few micrometers are fabricated by applying a silver sensor structure to glass. After sintering using an integrated laser or in an oven process, electrical conductivity is achieved within the sensor structure. Finally, we printed BSA in small micrometre-sized areas within the sensor structure using the same deposition system. The aerosol printing technology combined with material development offers great advantages for future-oriented applications involving biological surface functionalization on small areas. This is important for innovative biomedical micro-device development and for production solutions which bridge the disciplines of biology and electronics.

Magnetic iron oxide nanoparticles are considered for various diagnostic and therapeutic applications in brain including their use as contrast agent for magnetic resonance imaging or as tool for magnetic drug delivery. However, little is known so far on the consequences of a treatment of brain cells with such nanoparticles. In order to study the biocompatibility of iron oxide nanoparticles and the accumulation of iron from such particles in brain cells, we have used astrocyte-rich primary cultures as model system. Iron oxide nanoparticles were chemically synthesized with a yield of about 80% regarding the iron content. Transmission electron microscopy revealed that the synthesized iron oxide nanoparticles had a diameter of about 10 nm. Exposure of astrocyte cultures to 100 microM iron that were supplied as citrate-coated iron oxide nanoparticles did not cause any acute loss in cell viability but resulted in an almost linear increase in the cellular iron content that reached after 6 h of incubation at 37 degrees C a total cellular iron content of about 300 nmol/mg protein. The rate of iron accumulation from iron oxide nanoparticles was significantly higher than that from the low molecular weight iron complex ferric ammonium citrate (FAC). Lowering the incubation temperature from 37 degrees C to 4 degrees C reduced the iron accumulation rate from iron oxide nanoparticles or FAC by about 60%. In addition, presence of ferric or ferrous iron chelators did not affect the cellular iron accumulation from iron oxide nanoparticles. These data suggest that cultured astrocytes are able to accumulate intact iron oxide nanoparticles.

Magnetic iron oxide nanoparticles (Fe-NP) are considered for various applications in the brain. However, little is known so far on the uptake and the metabolism of such nanoparticles in brain cells. Since astrocytes are strategically localized between capillaries and neurons, astrocytes are of particular interest concerning uptake and fate of nanoparticles in the brain. Using astrocyte-rich primary cultures as model system we have investigated the accumulation of citrate-coated Fe-NP by astrocytes. Viable cultured astrocytes accumulate iron from citrate-coated Fe-NP in a time-, concentration-, and temperature-dependent manner. The cellular iron content determined after 4 h of incubation increases proportional to the concentration of Fe-NP, if the particles were applied in concentrations of up to 1000 x 10 -6 M of total iron. The iron accumulation from 500 or 1000 × 10- 6 M iron as Fe-NP is significantly slowed by lowering the incubation temperature from 37 to 4 °C. Transmission electron microscopy of the cells revealed that most of the cellular Fe-NP are present in intracellular vesicles. These data demonstrate that astrocytes accumulate efficiently citrate-coated Fe-NP, most likely by an endocytotic pathway.