Bioinspired Stimuli‐Responsive and Antifreeze‐Secreting Anti‐Icing Coatings

The detrimental impacts of icing on transportation and power industries are well‐known. Inspired by natural systems that secrete a functional liquid in response to stimuli, this work introduces an anti‐icing coating that responds to surface icing by releasing antifreeze liquid. It consists of an outer porous superhydrophobic epidermis and a wick‐like underlying dermis that is infused with antifreeze liquid. The functionality of the new coating is validated through condensation frosting, simulated freezing fog, and freezing rain experiments. In the tested conditions, the introduced anti‐icing skin delays onset of frost, rime, and glaze accumulation at least ten times longer than anti‐icing superhydrophobic and lubricant impregnated surfaces. Furthermore, the coating delays onset of glaze formation ten times longer than surfaces flooded with a thin film of antifreeze. In each of the icing scenarios, the fundamental mechanisms responsible for antifreeze release and their relation to required antifreeze replenishment rates are described.     

Bioinspired Surfaces with Superwettability for Anti‐Icing and Ice‐Phobic Application: Concept,Mechanism, and Design

Ice accumulation poses a series of severe issues in daily life. Inspired by the nature, superwettability surfaces have attracted great interests from fundamental research to anti‐icing and ice‐phobic applications. Here, recently published literature about the mechanism of ice prevention is reviewed, with a focus on the anti‐icing and ice‐phobic mechanisms, encompassing the behavior of condensate microdrops on the surface, wetting, ice nucleation, and freezing. Then, a detailed account of the innovative fabrication and fundamental research of anti‐icing materials with special wettability is summarized with a focus on recent progresses including low‐surface energy coatings and liquid‐infused layered coatings. Finally, special attention is paid to a discussion about advantages and disadvantages of the technologies, as well as factors that affect the anti‐icing and ice‐phobic efficiency. Outlooks and the challenges for future development of the anti‐icing and ice‐phobic technology are presented and discussed.     

Biotinylated Photopolymers for 3D‐Printed Unibody Lab‐on‐a‐Chip Optical Platforms

The present work reports the first demonstration of straightforward fabrication of monolithic unibody lab‐on‐a‐chip (ULOCs) integrating bioactive micrometric 3D scaffolds by means of multimaterial stereolithography (SL). To this end, a novel biotin‐conjugated photopolymer is successfully synthesized and optimally formulated to achieve high‐performance SL‐printing resolution, as demonstrated by the SL‐fabrication of biotinylated structures smaller than 100 µm. By optimizing a multimaterial single‐run SL‐based 3D‐printing process, such biotinylated microstructures are incorporated within perfusion microchambers whose excellent optical transparency enables real‐time optical microscopy analyses. Standard biotin‐binding assays confirm the existence of biotin‐heads on the surfaces of the embedded 3D microstructures and allow to demonstrate that the biofunctionality of biotin is not altered during the SL‐printing, thus making it exploitable for further conjugation with other biomolecules. As a step forward, an in‐line optical detection system is designed, prototyped via SL‐printing and serially connected to the perfusion microchambers through customized world‐to‐chip connectors. Such detection system is successfully employed to optically analyze the solution flowing out of the microchambers, thus enabling indirect quantification of the concentration of target interacting biomolecules. The successful application of this novel biofunctional photopolymer as SL‐material enables to greatly extend the versatility of SL to directly fabricate ULOCs with intrinsic biofunctionality.     

ta‐C beschichtete Werkzeuge für die Trockenumformung von Aluminiumblechen

ta‐C coated tools for dry forming of aluminum sheets The suitability of ta‐C coated tool surfaces for sheet forming of aluminum alloys was examined by strip‐draw testing. It was shown that ta‐C coatings, which are known as DLC coatings with superior wear resistance are also favourable concerning the anti‐adhesive behaviour. In attempts with AlMg5Mn‐ as well as Al99Mg1‐sheet materials several hundred sheets could be formed without noticeable aluminum adhering at the ta‐C coated tool surface. Neither the coefficients of friction nor the surface qualities of the aluminum sheets worsened during the observed period. Compared with tests of uncoated tools in combination with lubricants, the dry ta‐C coated tool behaves comparable with a good lubricant. In a real clinch test with aluminum sheets the positive results from strip‐draw experiments were confirmed. Using ta‐C coated clinching stamps and no lubricants a large number of clinching processes could be performed without noticeable adhering and increase of stripping forces.     

Solid‐Supported Biomolecules on Modified Silica Surfaces—A Tool for Fast Physicochemical Characterization and High‐Throughput Screening

Biofunctionalization for a wide variety of applications can be achieved by coating silica surfaces with biomolecules such as lipids or proteins. However, specific surface optimization of the inorganic SiO₂ is necessary to achieve biocompatible surfaces. Surface shielded porous silica beads can be non‐covalently coated with a single lipid bilayer. The lipids retain their fluidity in this handy solid‐supported system, perfectly mimicking the soft‐surface properties of cellular membranes. A supramolecular architecture can also be used for functional immobilization of membrane proteins: An artificial cytosolic compartment can be created with the aid of polymers; coating by lipid membranes and integration of membrane proteins results in a solid‐supported biofunctional cellular surface. Another surface modification enables a direct immobilization of human serum albumin (HSA) molecules onto silica surfaces. The HSA on this otherwise passivated surface provides a convenient material for the investigation of unspecific protein binding of pharmaceuticals on a high‐throughput scale.     

Plasma‐Induced Hetero‐Nanostructures on a Polymer with Selective Metal Co‐Deposition

Plasma‐induced pattern formation is explored on polyethylene terephthalate (PET) using an oxygen plasma glow discharge. The nanostructures on PET are formed through preferential etching directed by the co‐deposition of metallic elements, such as Cr or Fe, sputtered from a stainless‐steel cathode. The local islands formed by metal co‐deposition have significantly slower etching rates than those of the pristine regions on PET, generating anisotropic nanostructures in pillar‐ or hair‐like form during plasma etching. By covering the cathode with the appropriate material, the desired metallic or polymeric elements can be co‐deposited onto the target surfaces. When the cathode is covered by a relatively soft material composed of only carbon and hydrogen, such as polystyrene, nanostructures typically induced by preferential etching are not observed on the PET surface, and the surfaces are uniformly etched. A variety of metals, such as Ag, Cu, Pt, or Si, can be successfully co‐deposited onto the PET surfaces by simply using a cathode covered in the desired metal; high‐aspect‐ratio nanostructures coated with the co‐deposited metal are subsequently formed. Therefore this simple single‐step method for forming hetero‐nanostructures—that is, nanoscale hair‐like polymer structures decorated with metals—can be used to produce nanostructures for various applications, such as catalysts, sensors, or energy devices.     

Energy transfer: Visualizing Resonance Energy Transfer in Supramolecular Surface Patterns of β‐CD‐Functionalized Quantum Dot Hosts and Organic Dye Guests by Fluorescence Lifetime Imaging (Small 24/2010)

Detection of an analyte via supramolecular host–guest binding and quantum dot (QD)‐based fluorescence resonance energy transfer (FRET) signal transduction mechanism is demonstrated. Surface patterns consisting of CdSe/ZnS QDs functionalized at their periphery with β‐cyclodextrin (β‐CD) were obtained by immobilization of the QDs from solution onto glass substrates patterned with adamantyl‐terminated poly(propylene imine) dendrimeric “glue.” Subsequent formation of host–guest complexes between vacant β‐CD on the QD surface and an adamantyl‐functionalized lissamine rhodamine resulting in FRET was confirmed by fluorescence microscopy, spectroscopy, and fluorescence lifetime imaging microscopy (FLIM).     

Designing Lubricant‐Impregnated Textured Surfaces to Resist Scale Formation

Scale formation is a widespread problem in industries and households—from scaling of cooking pots in ancient times to the plugging of pipelines in the modern age. Developing surfaces that have a low affinity to scale has been an area of great interest in the last decade. In this work, we demonstrate the anti‐scaling properties of textured surfaces impregnated with a lubricant. Since scale deposition can be reduced by lowering the nucleation rate, which depends on the properties of the substrate, we optimize the design of the lubricant‐impregnated surfaces (LIS) based on the surface tension of the lubricant and its spreading coefficient on the solid. Scale deposition experiments show that the nucleation rate on optimized LIS is reduced owing to their low surface energy and low density of nucleation sites. Mass gain measurements indicate that the optimized LIS perform 10 times better than uncoated smooth surfaces. This idea is extended to an engineering material like stainless steel and, along with low scale deposition, low adhesion of scale to LIS is also achieved.     

Achieving One‐Step Surface Coating of Highly Hydrophilic Poly(Carboxybetaine Methacrylate) Polymers on Hydrophobic and Hydrophilic Surfaces

It is highly desirable to develop a universal nonfouling coating via a simple one‐step dip‐coating method. Developing such a universal coating method for a hydrophilic polymer onto a variety of surfaces with hydrophobic and hydrophilic properties is very challenging. This work demonstrates a versatile and simple method to attach zwitterionic poly(carboxybetaine methacrylate) (PCB), one of the most hydrophilic polymers, onto both hydrophobic and hydrophilic surfaces to render them nonfouling. This is achieved by the coating of a catechol chain end carboxybetaine methacrylate polymer (DOPA‐PCB) assisted by dopamine. The coating process was carried out in water. Water miscible solvents such as methanol and tetrahydrofuran (THF) are added to the coatings if surface wettability is an issue, as for certain hydrophobic surfaces. This versatile coating method was applied to several types of surfaces such as polypropylene (PP), polydimethyl siloxane (PDMS), Teflon, polystyrene (PS), polymethylmethacrylate (PMMA), polyvinyl chloride (PVC) and also on metal oxides such as silicon dioxide.     

Exploring the Nickel–Graphene Nanocomposite Coatings for Superior Corrosion Resistance: Manipulating the Effect of Deposition Current Density on its Morphology,Mechanical Properties,and Erosion‐Corrosion Performance

The use of graphene‐based composite as anti‐corrosion and protective coatings for metallic materials is still a provocative topic worthy of debate. Nickel–graphene nanocomposite coatings have been successfully fabricated onto the mild steel by electrochemical co‐deposition technique. This research demonstrates the properties of nickel–graphene composite coatings influenced by different electrodeposition current densities. The effect of deposition current density on the; surface morphologies, composition, microstructures, grain sizes, mechanical, and electrochemical properties of the composite coatings are executed. The coarseness of deposited coatings increases with the increasing of deposition current density. The carbon content in the composite coatings increases first and then decreases by further increasing of current density. The improved mechanical properties and superior anti‐corrosion performance of composite coatings are obtained at the peak value of current density of 9 A dm^?2. The incorporation of graphene sheets into nickel metal matrix lead to enhance the micro hardness, surface roughness, and adhesion strength of produced composite coatings. Furthermore, the presence of graphene in composite coating exhibits the reduced grain sizes and the enhanced erosion–corrosion resistance properties.

     

Kunststoffoptiken mit Antireflex‐ und Antibeschlageigenschaften durch Plasmaätzen und Beschichtung

Plastic optics exhibiting anti‐reflection and anti‐fogging properties produced by plasma etching and coating Plasma treatments are capable to generate antireflective surface structures on various polymers. On PMMA a self organized surface with nep‐like bumps exhibits excellent optical properties. Many other materials like polycarbonate, zeonex and lacquers can be etched after depositing a very thin initial layer to form a more holey structure. These surfaces attain high transmission values too and can be better stabilized by coatings than the nep‐ structure on PMMA. Interesting for practical applications are hydrophilic top‐layers to provide anti‐fogging properties in combination with improved transmission.     

Schäden wälzbeanspruchter DLC‐Schichten auf Stahlsubstraten unterschiedlicher Härte

Damages of slip‐rolling tested DLC coatings on steel substrates of different hardness Extremely hard diamond coatings on hard SSiC substrates, various hard DLC coatings on 100Cr6 substrates (HRC60) as well as selected DLC coatings on unhardened steel substrates (HRC20) were tested under slip‐rolling conditions. Unadditivated paraffin oil was used as a lubricant. The tests were carried out in an Amsler type twin disc tester at initial maximum pressures of P₀=2.3 GPa according to Hertz. The tests were terminated after n=1.000.000 revolutions (endurance tests: n=10.000.000 revolutions) or if a coherent damaged area of A>1 mm² occurred. The slip‐rolling tests showed that the SSiC had a supportive influence on the diamond coatings which, however, failed due to fractures in the substrate. At least two of the DLC coatings on 100Cr6 substrates (HRC60) withstood the slip‐rolling test for up to n=10.000.000 revolutions with nearly no visible damage. These coatings deposited onto a soft, nitrogen alloyed steel (HRC20) were able to adjust to the deformation of the substrate without major damaged areas (A>1 mm²).     

The Human In Vivo Biomolecule Corona onto PEGylated Liposomes: A Proof‐of‐Concept Clinical Study

The self‐assembled layered adsorption of proteins onto nanoparticle (NP) surfaces, once in contact with biological fluids, is termed the “protein corona” and it is gradually seen as a determinant factor for the overall biological behavior of NPs. Here, the previously unreported in vivo protein corona formed in human systemic circulation is described. The human‐derived protein corona formed onto PEGylated doxorubicin‐encapsulated liposomes (Caelyx) is thoroughly characterized following the recovery of liposomes from the blood circulation of ovarian carcinoma patients. In agreement with previous investigations in mice, the in vivo corona is found to be molecularly richer in comparison to its counterpart ex vivo corona. The intravenously infused liposomes are able to scavenge the blood pool and surface‐capture low‐molecular‐weight, low‐abundance plasma proteins that cannot be detected by conventional plasma proteomic analysis. This study describes the previously elusive or postulated formation of protein corona around nanoparticles in vivo in humans and illustrates that it can potentially be used as a novel tool to analyze the blood circulation proteome.     

Anti‐Icing Superhydrophobic Surfaces Based on Core‐Shell Fossil Particles

A novel approach for the design of functional coatings using fossil diatomaceous earth particles decorated by a thin layer of grafted polymer chains is reported. The polymer‐modified diatomaceous earth particles are able to form liquid marbles, superhydrophobic surfaces, and are highly promising for the design of anti‐icing coatings.     

Anti‐Eis‐Oberflächenbeschichtungen

Anti‐icing coating — optimization by means of plasma technology Ice on surfaces can significantly limit the function of devices and has to be removed by processes with high energy consumption. E. g., the formation of ice on rotor blades of wind turbines is not desired, on the wings of aircrafts it is even dangerous. With the aid of plasma technology, the Fraunhofer IGB has developed an anti‐icing coating for polymeric surfaces. Water‐repellent micro‐ and nanostructured coatings are applied to polymer foils made of impact‐resistant and shockproof polyurethane. Optimization of various process parameters has made it possible to produce ultra‐thin coatings, which reduces the ice's adhesion by over 90 percent. The new nanostructured foils open a wide range of applications.     

Aptamer‐Directed Synthesis of Multifunctional Lanthanide‐Doped Porous Nanoprobes for Targeted Imaging and Drug Delivery

Multifunctional lanthanide‐doped porous nanoparticles are prepared via a facile one‐step solvothermal route by employing aptamers as the biotemplate. The nanoparticles feature excellent aqueous dispersibility and biospecific properties and could work as effective nanoprobes for targeted imaging and drug delivery. With aptamer being in principle available for any kind of target, this synthetic strategy may open the door to a new generation of nanoprobes for bioapplications such as time‐resolved biodetection, multimode bioimaging/biolabeling, and targeted cancer therapy.     

Guiding Brain‐Tumor Surgery via Blood–Brain‐Barrier‐Permeable Gold Nanoprobes with Acid‐Triggered MRI/SERRS Signals

Surgical resection is a mainstay in the treatment of malignant brain tumors. Surgeons, however, face great challenges in distinguishing tumor margins due to their infiltrated nature. Here, a pair of gold nanoprobes that enter a brain tumor by crossing the blood–brain barrier is developed. The acidic tumor environment triggers their assembly with the concomitant activation of both magnetic resonance (MR) and surface‐enhanced resonance Raman spectroscopy (SERRS) signals. While the bulky aggregates continuously trap into the tumor interstitium, the intact nanoprobes in normal brain tissue can be transported back into the blood stream in a timely manner. Experimental results show that physiological acidity triggers nanoparticle assembly by forming 3D spherical nanoclusters with remarkable MR and SERRS signal enhancements. The nanoprobes not only preoperatively define orthotopic glioblastoma xenografts by magnetic resonance imaging (MRI) with high sensitivity and durability in vivo, but also intraoperatively guide tumor excision with the assistance of a handheld Raman scanner. Microscopy studies verify the precisely demarcated tumor margin marked by the assembled nanoprobes. Taking advantage of the nanoprobes' rapid excretion rate and the extracellular acidification as a hallmark of solid tumors, these nanoprobes are promising in improving brain‐tumor surgical outcome with high specificity, safety, and universality.     

Multiscale Plasma‐Catalytic On‐Surface Assembly

Controlled modification of surfaces is one of the key pursuits of the nanoscience and nanotechnology fields, allowing for the fabrication of bespoke materials with targeted functionalities. However, many surface modifications currently require painstakingly precise and/or energy intensive processing to implement, and are thus limited in scope and scale. Here, a concept which can enhance the capacity for control of surfaces is introduced: plasma‐assisted nucleation and self‐assembly at atomic to nanoscales, scalable at atmospheric pressures.     

Superhydrophobic Coatings on Cellulose‐Based Materials: Fabrication,Properties, and Applications

Wettability of a solid surface by a liquid plays an important role in several phenomena and applications, for example in adhesion, printing, and self‐cleaning. In particular, wetting of rough surfaces has attracted great scientific interest in recent decades. Superhydrophobic surfaces, which possess extraordinary water repelling properties due to their low surface energy and specific nanometer‐ and micrometer‐scale roughness, are of particular interest due to the great variety of potential applications ranging from self‐cleaning surfaces to microfluidic devices. In recent years, the potential of superhydrophobic cellulose‐based materials in the function of smart devices and functional clothing has been recognized, and in the past few years cellulose‐based materials have established themselves among the most frequently used substrates for superhydrophobic coatings. In this Review, over 40 different approaches to fabricate superhydrophobic coatings on cellulose‐based materials are discussed in detail. In addition to the anti‐wetting properties of the coatings, particular attention is paid to coating durability and other incorporated functionalities such as gas permeability, transparency, UV‐shielding, photoactivity, and self‐healing properties. Potential applications for the superhydrophobic cellulose‐based materials range from water‐ and stain‐repellent, self‐cleaning and breathable clothing to cheap and disposable lab‐on‐a‐chip devices made from renewable sources with reduced material consumption.