Screening of Nanocomposite Scaffolds Arrays Using Superhydrophobic‐Wettable Micropatterns

Platforms containing multiple arrays for high‐throughput screening are demanded in the development of biomaterial libraries. Here, an array platform for the combinatorial analysis of cellular interactions and 3D porous biomaterials is described. Using a novel method based on computer‐aided manufacturing, wettable regions are printed on superhydrophobic surfaces, generating isolated spots. This freestanding benchtop array is used as a tool to deposit naturally derived polymers, chitosan and hyaluronic acid, with bioactive glass nanoparticles (BGNPs) to obtain a scaffold matrix. The effect of fibronectin adsorption on the scaffolds is also tested. The biomimetic nanocomposite scaffolds are shown to be osteoconductive, non‐cytotoxic, promote cell adhesion, and regulate osteogenic commitment. The method proves to be suitable for screening of biomaterials in 3D cell cultures as it can recreate a multitude of combinations on a single platform and identify the optimal composition that drives to desired cell responses. The platforms are fully compatible with commercially routine cell culture labware and established characterization methods, allowing for a standard control and easy adaptability to the cell culture environment. This study shows the value of 3D structured array platforms to decode the combinatorial interactions at play in cell microenvironments.     

High Throughput,Polymeric Aqueous Two‐Phase Printing of Tumor Spheroids

This paper presents a new 3D culture microtechnology for high throughput production of tumor spheroids and validates its utility for screening anti‐cancer drugs. Two immiscible polymeric aqueous solutions are used and a submicroliter drop of the “patterning” phase containing cells is microprinted into a bath of the “immersion” phase. Selecting proper formulations of biphasic systems using a panel of biocompatible polymers results in the formation of a round drop that confines cells to facilitate spontaneous formation of a spheroid without any external stimuli. Adapting this approach to robotic tools enables straightforward generation and maintenance of spheroids of well‐defined size in standard microwell plates and biochemical analysis of spheroids in situ, which is not possible with existing techniques for spheroid culture. To enable high throughput screening, a phase diagram is established to identify minimum cell densities within specific volumes of the patterning drop to result in a single spheroid. Spheroids show normal growth over long‐term incubation and dose‐dependent decrease in cellular viability when treated with drug compounds, but present significant resistance compared to monolayer cultures. The unprecedented ease of implementing this microtechnology and its robust performance will benefit high throughput studies of drug screening against cancer cells with physiologically relevant 3D tumor models.     

Design of Multistimuli Responsive Hydrogels Using Integrated Modeling and Genetically Engineered Silk–Elastin‐Like Proteins

Elastomeric, robust, and biocompatible hydrogels are rare, while the need for these types of biomaterials in biomedical‐related uses remains high. Here, a new family of genetically engineered silk–elastin‐like proteins (SELPs) with encoded enzymatic crosslinking sites is developed for a new generation of stimuli‐responsive yet robust hydrogels. Input into the designs is guided by simulation and realized via genetic engineering strategies. The avoidance of gamma irradiation or chemical crosslinking during gel fabrication, in lieu of an enzymatic process, expands the versatility of these new gels for the incorporation of labile proteins and cells. In the present study, the new SELP hydrogels offer sequence‐dependent, reversible stimuli‐responsive features. Their stiffness covers almost the full range of the elasticity of soft tissues. Further, physical modification of the silk domains provides a secondary control point to fine‐tune mechanical stiffness while preserving stimuli‐responsive features, with implications for a variety of biomedical material and device needs.     

Blood‐Inert Surfaces via Ion‐Pair Anchoring of Zwitterionic Copolymer Brushes in Human Whole Blood

A strategy to create blood‐inert surfaces in human whole blood via ion‐pair anchoring of zwitterionic copolymer brushesand a systematic study of how well‐defined chain lengths and well‐controlled surface packing densities of zwitterionic polymers affect blood compatibility are reported. Well‐defined diblock copolymers, poly(11‐mercaptoundecyl sulfonic acid)‐block‐poly(sulfobetaine methacrylate) (PSA‐b‐PSBMA) with varying zwitterionic PSBMA or negatively charged PSA lengths, are synthesized via atom‐transfer radical polymerization (ATRP). PSA‐b‐PSBMA is grafted onto a surface covered with polycation brushes as a mimic polar/hydrophilic biomaterial surface via ion‐pair anchoring at a range of copolymer concentrations. Protein adsorption from single‐protein solutions, 100% blood serum, and 100% blood plasma onto the surfaces covered with PSA‐b‐PSBMA brushes is evaluated using a surface plasmon resonance sensor. Copolymer brushes containing a high amount of zwitterionic SBMA units are further challenged with human whole blood. Low protein‐fouling surfaces with >90% reduction with respect to uncoated surfaces are achieved with longer PSA blocks and higher concentrations of PSA‐b‐PSBMA copolymers using the ion‐pair anchoring approach. This work provides a platform to achieve the control of various surface parameters and a practical method to create blood‐inert surfaces in whole blood by grafting ionic‐zwitterionic copolymers to charged biomaterials via charge pairing.     

Spatiotemporal Control over Molecular Delivery and Cellular Encapsulation from Electropolymerized Micro‐ and Nanopatterned Surfaces

Bioactive, patterned micro‐ and nanoscale surfaces that can be spatially engineered for three‐dimensional ligand presentation and sustained release of signaling molecules represent a critical advance for the development of next‐generation diagnostic and therapeutic devices. Lithography is ideally suited to patterning such surfaces due to its precise, easily scalable, high‐throughput nature; however, to date polymers patterned by these techniques have not demonstrated the capacity for sustained release of bioactive agents. Here a class of lithographically defined, electropolymerized polymers with monodisperse micro‐ and nanopatterned features capable of sustained release of bioactive drugs and proteins is demonstrated. It is shown that precise control can be achieved over the loading capacity and release rates of encapsulated agents and this aspect is illustrated using a fabricated surface releasing a model antigen (ovalbumin) and a cytokine (interleukin‐2) for induction of a specific immune response. Furthermore, the ability of this technique to enable three‐dimensional control over cellular encapsulation is demonstrated. The efficacy of the described approach is buttressed by its simplicity, versatility, and reproducibility, rendering it ideally suited for biomaterials engineering.     

Cell‐Instructive Multiphasic Gel‐in‐Gel Materials

Developing tissue is typically soft, highly hydrated, dynamic, and increasingly heterogeneous matter. Recapitulating such characteristics in engineered cell‐instructive materials holds the promise of maximizing the options to direct tissue formation. Accordingly, progress in the design of multiphasic hydrogel materials is expected to expand the therapeutic capabilities of tissue engineering approaches and the relevance of human 3D in vitro tissue and disease models. Recently pioneered methodologies allow for the creation of multiphasic hydrogel systems suitable to template and guide the dynamic formation of tissue‐ and organ‐specific structures across scales, in vitro and in vivo. The related approaches include the assembly of distinct gel phases, the embedding of gels in other gel materials and the patterning of preformed gel materials. Herein, the capabilities and limitations of the respective methods are summarized and discussed and their potential is highlighted with some selected examples of the recent literature. As the modularity of the related methodologies facilitates combinatorial and individualized solutions, it is envisioned that multiphasic gel‐in‐gel materials will become a versatile morphogenetic toolbox expanding the scope and the power of bioengineering technologies.     

Highly Scalable,Closed‐Loop Synthesis of Drug‐Loaded,Layer‐by‐Layer Nanoparticles

Layer‐by‐layer (LbL) self‐assembly is a versatile technique from which multi­component and stimuli‐responsive nanoscale drug‐carriers can be constructed. Despite the benefits of LbL assembly, the conventional synthetic approach for fabricating LbL nanoparticles requires numerous purification steps that limit scale, yield, efficiency, and potential for clinical translation. In this report, a generalizable method for increasing throughput with LbL assembly is described by using highly scalable, closed‐loop diafiltration to manage intermediate purification steps. This method facilitates highly controlled fabrication of diverse nanoscale LbL formulations smaller than 150 nm composed from solid‐polymer, mesoporous silica, and liposomal vesicles. The technique allows for the deposition of a broad range of polyelectrolytes that included native polysaccharides, linear polypeptides, and synthetic polymers. The cytotoxicity, shelf life, and long‐term storage of LbL nanoparticles produced using this approach are explored. It is found that LbL coated systems can be reliably and rapidly produced: specifically, LbL‐modified liposomes could be lyophilized, stored at room temperature, and reconstituted without compromising drug encapsulation or particle stability, thereby facilitating large scale applications. Overall, this report describes an accessible approach that significantly improves the throughput of nanoscale LbL drug‐carriers that show low toxicity and are amenable to clinically relevant storage conditions.     

HSG‐ad hoc network: A novel hierarchical star graph ad hoc network with self‐organization and routing discovery free

In ad hoc wireless networks, most data are delivered by multi‐hop routing (hop by hop). This approach may cause long delay and a high routing overhead regardless of which routing protocol is used. To mitigate this inherent characteristic, this work presents a novel ad hoc network structure that adopts dual‐card‐mode, self‐organization with specific IP naming and channel assignment to form a hierarchical star graph ad hoc network (HSG‐ad hoc). This network not only expedites data transmission but also eliminates the route discovery procedure during data transmission. Therefore, the overall network reliability and stability are significantly improved. Simulation results show that the proposed approach achieves substantial improvements over DSDV, AODV, and DSR in terms of average end‐to‐end delay, throughput, and packet delivery ratio. Copyright © 2009 John Wiley & Sons, Ltd.     

Biomimetic Miniaturized Platform Able to Sustain Arrays of Liquid Droplets for High‐Throughput Combinatorial Tests

The development of high‐throughput and combinatorial technologies is helping to speed up research that is applicable in many areas of chemistry, engineering, and biology. A new model is proposed for flat devices for the high‐throughput screening of accelerated evaluations of multiplexed processes and reactions taking place in aqueous‐based environments. Superhydrophobic (SH) biomimetic surfaces based on the so‐called lotus effect are produced, onto which arrays of micro‐indentations allow the fixing of liquid droplets, based on the rose‐petal effect. The developed platforms are able to sustain arrays of quasi‐spherical microdroplets, allowing the isolation and confinement of different combinations of substances and living cells. Distinct compartmentalized physical, chemical, and biological processes may take place and be monitored in each droplet. The devices permit the addition/removal of liquid and mechanical stirring by adding magnetic microparticles into each droplet. By facing the chip downward, it is possible to produce arrays of cell spheroids developed by gravity in the suspended droplets, with the potential to be used as microtissues in drug screening tests.     

High‐Throughput Combinatorial Optimizations of Perovskite Light‐Emitting Diodes Based on All‐Vacuum Deposition

Light‐emitting diodes (LEDs) based on lead halide perovskites demonstrate outstanding optoelectronic properties and are strong competitors for display and lighting applications. While previous halide perovskite LEDs are mainly produced via solution processing, here an all‐vacuum processing method is employed to construct CsPbBr₃ LEDs because vacuum processing exhibits high reliability and easy integration with existing OLED facilities for mass production. The high‐throughput combinatorial strategies are further adopted to study perovskite composition, annealing temperature, and functional layer thickness, thus significantly speeding up the optimization process. The best rigid device shows a current efficiency (CE) of 4.8 cd A^?1 (EQE of 1.45%) at 2358 cd m^?2, and best flexible device shows a CE of 4.16 cd A^?1 (EQE of 1.37%) at 2012 cd m^?2 with good bending tolerance. Moreover, by choosing NiO_x as the hole‐injection layer, the CE is improved to 10.15 cd A^?1 and EQE is improved to a record of 3.26% for perovskite LEDs produced by vacuum deposition. The time efficient combinatorial approaches can also be applied to optimize other perovskite LEDs.     

Poly[oligo(ethylene glycol) methacrylate‐co‐glycidyl methacrylate] Brush Substrate for Sensitive Surface Plasmon Resonance Imaging Protein Arrays

Surface plasmon resonance imaging (SPRi) is a unique microarray method for label‐free and multiplexed bio‐assays. However, it currently cannot be used to detect human serum samples due to its low sensitivity and poor specificity. A poly[oligo(ethylene glycol) methacrylate‐co‐glycidyl methacrylate] (POEGMA‐co‐GMA) brush was synthesized by surface‐initiated atom transfer radical polymerization (SI‐ATRP) and used as a unique supporting matrix for SPRi arrays to efficiently load probe proteins for high sensitivity while reducing nonspecific adsorptions for good selectivity. Results indicate that the polymer brush has a high protein loading capacity (1.8 protein monolayers), low non‐specific protein adsorption (below the SPR detection limit), and high immobilization stability. Three model biomarkers, α‐fetoprotein, carcinoembryonic antigen, and hepatitis B surface antigen were simultaneously detected in human serum samples by a SPRi chip for the first time, showing detection limits of 50, 20, and 100 ng mL^?1, respectively. This work demonstrates great potential for a SPRi biochip as a powerful label‐free and high‐throughput detection tool in clinical diagnosis and biological research. Since the SPR detection is limited by the sensing film thickness, this approach particularly offers a unique way to significantly improve the sensitivity in the SPR detecting thickness range.     

New Roll‐to‐Roll Processable PEDOT‐Based Polymer with Colorless Bleached State for Flexible Electrochromic Devices

Conjugated electrochromic (EC) polymers for flexible EC devices (ECDs) generally lack a fully colorless bleached state. A strategy to overcome this drawback is the implementation of a new sidechain‐modified poly(3,4‐ethylene dioxythiophene) derivative that can be deposited in thin‐film form in a customized high‐throughput and large‐area roll‐to‐roll polymerization process. The sidechain modification provides enhanced EC properties in terms of visible light transmittance change, Δτ_v = 59% (ΔL* = 54.1), contrast ratio (CR = 15.8), coloration efficiency (η = 530 cm² C^?1), and color neutrality (L* = 83.8, a* = ?4.3, b* = ?4.1) in the bleached state. The intense blue‐colored polymer thin films exhibit high cycle stability (10 000 cycles) and fast response times. The design, synthesis, and polymerization of the modified 3,4‐ethylene dioxythiophene derivative are discussed along with a detailed optical, electrochemical, and spectroelectrochemical characterization of the resulting EC thin films. Finally, a flexible see‐through ECD with a visible light transmittance change of Δτ_v = 47% (ΔL* = 51.9) and a neutral‐colored bleached state is developed.     

Rapid and Facile Microwave‐Assisted Surface Chemistry for Functionalized Microarray Slides

This report describes a rapid and facile method for surface functionalization and ligand patterning of glass slides based on microwave‐assisted synthesis and a microarraying robot. The optimized reaction enables surface modification 42‐times faster than conventional techniques and includes a carboxylated self‐assembled monolayer, polyethylene glycol linkers of varying length, and stable amide bonds to small molecule, peptide, or protein ligands to be screened for binding to living cells. Customized slide racks that permit functionalization of 100 slides at a time to produce a cost‐efficient, highly reproducible batch process. Ligand spots can be positioned on the glass slides precisely using a microarraying robot, and spot size adjusted for any desired application. Using this system, live cell binding to a variety of ligands is demonstrate and PEG linker length is optimized. Taken together, the technology we describe should enable high‐throughput screening of disease‐specific ligands that bind to living cells.     

Nanoengineering Hybrid Supramolecular Multilayered Biomaterials Using Polysaccharides and Self‐Assembling Peptide Amphiphiles

Developing complex supramolecular biomaterials through highly dynamic and reversible noncovalent interactions has attracted great attention from the scientific community aiming key biomedical and biotechnological applications, including tissue engineering, regenerative medicine, or drug delivery. In this study, the authors report the fabrication of hybrid supramolecular multilayered biomaterials, comprising high‐molecular‐weight biopolymers and oppositely charged low‐molecular‐weight peptide amphiphiles (PAs), through combination of self‐assembly and electrostatically driven layer‐by‐layer (LbL) assembly approach. Alginate, an anionic polysaccharide, is used to trigger the self‐assembling capability of positively charged PA and formation of 1D nanofiber networks. The LbL technology is further used to fabricate supramolecular multilayered biomaterials by repeating the alternate deposition of both molecules. The fabrication process is monitored by quartz crystal microbalance, revealing that both materials can be successfully combined to conceive stable supramolecular systems. The morphological properties of the systems are studied by advanced microscopy techniques, revealing the nanostructured dimensions and 1D nanofibrous network of the assembly formed by the two molecules. Enhanced C2C12 cell adhesion, proliferation, and differentiation are observed on nanostructures having PA as outermost layer. Such supramolecular biomaterials demonstrate to be innovative matrices for cell culture and hold great potential to be used in the near future as promising biomimetic supramolecular nanoplatforms for practical applications.     

Optimal Planar Array Architecture for Full‐Dimensional Multi‐user Multiple‐Input Multiple‐Output with Elevation Modeling

Research interest in three‐dimensional multiple‐input multiple‐output (3D‐MIMO) beamforming has rapidly increased on account of its potential to support high data rates through an array of strategies, including sector or user‐specific elevation beamforming and cell‐splitting. To evaluate the full performance benefits of 3D and full‐dimensional (FD) MIMO beamforming, the 3D character of the real MIMO channel must be modeled with consideration of both the azimuth and elevation domain. Most existing works on the 2D spatial channel model (2D‐SCM) assume a wide range for the distribution of elevation angles of departure (eAoDs), which is not practical according to field measurements. In this paper, an optimal FD‐MIMO planar array configuration is presented for different practical channel conditions by restricting the eAoDs to a finite range. Using a dynamic network level simulator that employs a complete 3D SCM, we analyze the relationship between the angular spread and sum throughput. In addition, we present an analysis on the optimal antenna configurations for the channels under consideration.     

Systematic Study of Widely Applicable N‐Doping Strategy for High‐Performance Solution‐Processed Field‐Effect Transistors

A specific design for solution‐processed doping of active semiconducting materials would be a powerful strategy in order to improve device performance in flexible and/or printed electronics. Tetrabutylammonium fluoride and tetrabutylammonium hydroxide contain Lewis base anions, F^? and OH^?, respectively, which are considered as organic dopants for efficient and cost‐effective n‐doping processes both in n‐type organic and nanocarbon‐based semiconductors, such as poly[[N,N′‐bis(2‐octyldodecyl)‐naphthalene‐1,4,5,8‐bis(dicarboximide)‐2,6‐diyl]‐alt‐5,5′‐(2,2′‐bithiophene)] (P(NDI2OD‐T2)) and selectively dispersed semiconducting single‐walled carbon nanotubes by π‐conjugated polymers. The dramatic enhancement of electron transport properties in field‐effect transistors is confirmed by the effective electron transfer from the dopants to the semiconductors as well as controllable onset and threshold voltages, convertible charge‐transport polarity, and simultaneously showing excellent device stabilities under ambient air and bias stress conditions. This simple solution‐processed chemical doping approach could facilitate the understanding of both intrinsic and extrinsic charge transport characteristics in organic semiconductors and nanocarbon‐based materials, and is thus widely applicable for developing high‐performance organic and printed electronics and optoelectronics devices.     

Polymers Containing Highly Polarizable Conjugated Side Chains as High‐Performance All‐Organic Nanodielectric Materials

The discovery of nanodipolar π‐conjugated oligomer‐containing polymers as high performance nanodielectric materials with high permittivity and low dielectric loss over a wide range of frequency (100 Hz–4 MHz) is reported. Terthiophene‐containing methacrylate polymers are synthesized by reversible addition fragmentation transfer (RAFT) polymerization. Both X‐ray and thermal studies indicate the formation of small crystalline domains of terthiophene side chains dispersed in amorphous matrix. The highly polarizable and fast‐responsive nanodipoles from the nanoscale crystalline domains (<2 nm) are believed to dictate the performance. These polymers uniquely satisfy nanodipole architectures conjectured two decades ago to guide the design of high performance nanodielectric materials. This unprecedented approach can be generalized to a variety of π‐conjugated oligomer‐containing polymers for the development of high energy density capacitor materials.     

Flipping the Switch on Clathrin‐Mediated Endocytosis using Thermally Responsive Protein Microdomains

A ubiquitous approach to studying protein function is to knock down activity (gene deletions, siRNA, small molecule inhibitors, etc.) and to study the cellular effects. Using a new methodology, this article describes how to rapidly and specifically switch off cellular pathways using thermally responsive protein polymers. A small increase in temperature stimulates cytosolic elastin‐like polypeptides (ELPs) to assemble microdomains. It is hypothesized that ELPs fused to a key effector in a target macromolecular complex will sequester the complex within these microdomains, which will bring the pathway to a halt. To test this hypothesis, ELPs are fused to clathrin‐light chain (CLC), a protein associated with clathrin‐mediated endocytosis. Prior to thermal stimulation, the ELP fusion is soluble and clathrin‐mediated endocytosis remains “on”. Increasing the temperature induces the assembly of ELP fusion proteins into organelle‐sized microdomains that switches clathrin‐mediated endocytosis “off”. These microdomains can be thermally activated and inactivated within minutes, are reversible, do not require exogenous chemical stimulation, and are specific for components trafficked within the clathrin‐mediated endocytosis pathway. This temperature‐triggered cell switch system represents a new platform for the temporal manipulation of trafficking mechanisms in normal and disease cell models and has applications for manipulating other intracellular pathways.     

Functional and Well‐Defined β‐Sheet‐Assembled Porous Spherical Shells by Surface‐Guided Peptide Formation

Polypeptides have attracted widespread attention as building blocks for complex materials due to their ability to form higher‐ordered structures such as β‐sheets. However, the ability to precisely control the formation of well‐defined β‐sheet‐assembled materials remains challenging as β‐sheet formation tends to lead to ill‐defined and unprocessable aggregates. This work reports a simple, rapid, and robust strategy to form well‐defined peptide β‐sheet‐assembled shells (i.e., hollow spheres) by employing surface‐initiated N‐carboxyanhydride ring‐opening polymerization under a highly efficient surface‐driven approach. The concept is demonstrated by the preparation of enzyme‐degradable rigid shell architectures composed of H‐bonded poly(L‐valine) (PVal) grafts with porous and sponge‐like surface morphology. The porous PVal‐shells exhibit a remarkable and unprecedented ability to non‐covalently entrap metal nanoparticles, proteins, drug molecules, and biorelevant polymers, which could potentially lead to a diverse range of biodegradable and functional platforms for applications ranging from therapeutic delivery to organic catalysis.     

High‐Strain Shape‐Memory Polymers

Shape‐memory polymers (SMPs) are self‐adjusting, smart materials in which shape changes can be accurately controlled at specific, tailored temperatures. In this study, the glass transition temperature (T_g) is adjusted between 28 and 55 °C through synthesis of copolymers of methyl acrylate (MA), methyl methacrylate (MMA), and isobornyl acrylate (IBoA). Acrylate compositions with both crosslinker densities and photoinitiator concentrations optimized at fractions of a mole percent demonstrate fully recoverable strains at 807% for a T_g of 28 °C, at 663% for a T_g of 37 °C, and at 553% for a T_g of 55 °C. A new compound, 4,4′‐di(acryloyloxy)benzil (referred to hereafter as Xini) in which both polymerizable and initiating functionalities are incorporated in the same molecule, was synthesized and polymerized into acrylate shape‐memory polymers, which were thermomechanically characterized yielding fully recoverable strains above 500%. The materials synthesized in this work were compared to an industry standard thermoplastic SMP, Mitsubishi's MM5510, which showed failure strains of similar magnitude, but without full shape recovery: residual strain after a single shape‐memory cycle caused large‐scale disfiguration. The materials in this study are intended to enable future applications where both recoverable high‐strain capacity and the ability to accurately and independently position T_g are required.