Superassembled Biocatalytic Porous Framework Micromotors with Reversible and Sensitive pH‐Speed Regulation at Ultralow Physiological H2O2 Concentration

Synthetic nano/micromotors are a burgeoning class of materials with vast promise for applications ranging from environmental remediation to nanomedicine. The motility of these motors is generally controlled by the concentration of accessible fuel, and therefore, engineering speed‐regulation mechanisms, particularly using biological triggers, remains a continuing challenge. Here, control over the movement of superassembled porous framework micromotors via a reversible, biological‐relevant pH‐responsive regulatory mechanism is demonstrated. Succinylated β‐lactoglobulin and catalase are superassembled in porous framework particles, where the β‐lactoglobulin is permeable at neutral pH. This permeability allows the fuel (H₂O₂) to access catalase, leading to autonomous movement of the micromotors. However, at mild acidic pH, succinylated β‐lactoglobulin undergoes a reversible gelation process, preventing the access of fuel into the micromotors where the catalase resides. To one's knowledge, this study represents the first example of chemically driven motors with rapid, reversible pH‐responsive motility. Furthermore, the porous framework significantly enhances the biocatalytic activity of catalase, allowing ultralow H₂O₂ concentrations to be exploited at physiological conditions. It is envisioned that the simultaneous exploitation of pH and chemical potential of such nanosystems could have potential applications as stimulus‐responsive drug delivery vehicles that benefit from the complex biological environment.     

A Magneto-Responsive Hydrogel System for the Dynamic Mechano-Modulation of Stem Cell Niche

The biophysical microenvironment of cells dynamically evolves during embryonic development, leading to defined tissue specification. A versatile and highly adaptive magneto-responsive hydrogel system composed of magnetic nanorods (MNRs) and a stress-responsive polymeric matrix is developed to dynamically regulate the physical stem cell niche. The anisotropic magnetic/shape factor of nanorods is utilized to maximize the strains on the polymeric network, thus regulating the hydrogel modulus in a physiologically relevant range under a minimal magnitude of the applied magnetic fields below 4.5 mT. More significantly, the pre-alignment of MNRs induces greater collective strains on the polymeric network, resulting in a superior stiffening range, over a 500% increase as compared to that with randomly oriented nanorods. The pre-alignment of nanorods also enables a fast and reversible response under a magnetic field of the opposite polarity as well as spatially controlled heterogeneity of modulus within the hydrogel by applying anisotropic magnetic fields. The mechano-modulative capability of this system is validated by a mechanotransduction model with human-induced pluripotent stem cells where the locally controlled hydrogel modulus regulates the activation of mechano-sensitive signaling mediators and subsequent stem cell differentiation. Therefore, this magneto-responsive hydrogel system provides a platform to investigate various cellular behaviors under dynamic mechanical microenvironments.     

Functional Hydrogel Surfaces: Binding Kinesin‐Based Molecular Motor Proteins to Selected Patterned Sites

Hydrogel microstructures with micrometer‐scale topography and controllable functionality have great potential for numerous nanobiotechnology applications including, for example, three‐dimensional structures that exhibit controlled interactions with proteins and cells. Taking advantage of the strong affinity of histidine (His) residues for metal‐ion–nitrilotriacetic acid (NTA) complexes, we have chemically modified hydrogels to enable protein immobilization with retention of activity by incorporating 2‐methacrylamidobutyl nitrilotriacetic acid, an NTA‐containing monomer that can be copolymerized with a series of monomers to form NTA‐containing hydrogels. By varying the NTA‐monomer composition in the hydrogels, it is possible to control the amount of protein bound to the hydrogel surface. The retention of biological activity was demonstrated by microtubule gliding assays. Normally, hydrogels are resistant to protein binding, but we have selected these materials because of their porous nature. Bringing together hydrogel functionalization and soft‐lithography patterning techniques, it was possible to create a hybrid hydrogel superstructure that possesses binding specificity to His‐tagged protein in selected sites. This type of surface and microstructure is not only advantageous for motor protein integration, but it can also be generally applied to the formation of His‐tagged molecules for sensors and biochip applications.     

Mobile access to biological databases on the Internet

We have developed a new way of accessing biological databases and bioinformatics applications on the Internet. This new service, bioinformatics wireless application protocol (BioWAP) service, which is accessible by mobile devices makes it possible to access bioinformatics services, where normal PC or personal digital assistant (PDA) connections are not feasible. The BioWAP service includes major biological databases and applications demonstrating a simple method of implementing WAP interfaces to uncompliant applications, i.e. the applications that are not WAP or Internet based. The BioWAP service can be browsed with any WAP terminal.     

Cellulose Gel Mechanoreceptors – Principles,Applications and Prospects

In order to effectively harness varieties of mechanical waves or vibrations for the purpose of monitoring and/or powering, developments in responsive materials and conversion technologies are taking place driven by the world's current and future demands. One of the most popular novelties of the last two decades is represented by hydrogel- or ionogel-based flexible iontronics which constitute a wide family of innovative smart (self-powered) mechanoreceptors relevant for various applications such as personal health care, identity and safety monitoring, intelligent human-machine operation interfaces, underwater listening and communication, and so on. Cellulosic gels (CGs), as a promising green substitute for fossil fuel-derived materials, are extensively studied due to the possibility to choose between different cellulose types and to formulate networks chemically or physically, according to the adaptability requirements for each target application. The aim of this review is to showcase the cellulose structural versatility and to provide a summary of the principles during the formulation of CGs used for mechanosensing and mechanical energy scavenging, as well as their practical applications. Such an outlook of current challenges and overall prospects will serve as a stimulus for research on CG-based mechanoreceptors in the future.     

Skin‐Inspired Antibacterial Conductive Hydrogels for Epidermal Sensors and Diabetic Foot Wound Dressings

Recently, artificial intelligence research has driven the development of stretchable and flexible electronic systems. Conductive hydrogels are a class of soft electronic materials that have emerging applications in wearable and implantable biomedical devices. However, current conductive hydrogels possess fundamental limitations in terms of their antibacterial performance and a mechanical mismatch with human tissues, which severely limits their applications in biological interfaces. Here, inspired by animal skin, a conductive hydrogel is fabricated from a supramolecular assembly of polydopamine decorated silver nanoparticles (PDA@Ag NPs), polyaniline, and polyvinyl alcohol, namely PDA@Ag NPs/CPHs. The resultant hydrogel has many desirable features, such as tunable mechanical and electrochemical properties, eye‐catching processability, good self‐healing ability as well as repeatable adhesiveness. Remarkably, PDA@Ag NPs/CPHs exhibit broad antibacterial activity against Gram‐negative and Gram‐positive bacteria. The potential application of this versatile hydrogel is demonstrated by monitoring large‐scale movements of the human body in real time. In addition, PDA@Ag NPs/CPHs have a significant therapeutic effect on diabetic foot wounds by promoting angiogenesis, accelerating collagen deposition, inhibiting bacterial growth, and controlling wound infection. To the best of the authors' knowledge, this is the first time that conductive hydrogels with antibacterial ability are developed for use as epidermal sensors and diabetic foot wound dressing.     

Exploitation of Diatom Frustules for Nanotechnology: Tethering Active Biomolecules

Diatoms are single‐celled microalgae with rigid walls (frustules) composed of amorphous silica. The intricate 3D microstructure of diatoms results in a high surface area formed by myriad pores and channels. The combination of the silica chemistry of the frustule coupled with the high surface area makes it particularly suitable for applications such as microscale total analysis systems. Here it is demonstrated that the diatom frustule can be chemically modified for the attachment of antibodies, and that the attached antibodies retain biological activity. These modified structures have potential applications in antibody arrays and may have use in techniques such as immunoprecipitation. These silica structures are produced in diatoms using only light and minimal nutrients and, therefore, generate an exceptionally cheap and renewable material.     

The Devices,Experimental Scaffolds,and Biomaterials Ontology (DEB): A Tool for Mapping,Annotation, and Analysis of Biomaterials Data

The size and complexity of the biomaterials literature makes systematic data analysis an excruciating manual task. A practical solution is creating databases and information resources. Implant design and biomaterials research can greatly benefit from an open database for systematic data retrieval. Ontologies are pivotal to knowledge base creation, serving to represent and organize domain knowledge. To name but two examples, GO, the gene ontology, and CheBI, Chemical Entities of Biological Interest ontology and their associated databases are central resources to their respective research communities. The creation of the devices, experimental scaffolds, and biomaterials ontology (DEB), an open resource for organizing information about biomaterials, their design, manufacture, and biological testing, is described. It is developed using text analysis for identifying ontology terms from a biomaterials gold standard corpus, systematically curated to represent the domain's lexicon. Topics covered are validated by members of the biomaterials research community. The ontology may be used for searching terms, performing annotations for machine learning applications, standardized meta‐data indexing, and other cross‐disciplinary data exploitation. The input of the biomaterials community to this effort to create data‐driven open‐access research tools is encouraged and welcomed.     

Elemental characterisation of sub 20 nm structures in devices using new SEM-EDS technology

The continuing decrease in structure and defect size in devices has driven many applications away from SEM towards thin sample preparation and TEM investigation. The latest FIB/SEM technology has the capability to image structures down to less than 5 nm on a bulk or thin specimen but cannot provide supporting chemical information from EDS. Here we investigate a new more sensitive EDS detector, which for the first time provides chemical information at these high spatial resolutions in the SEM. We outline operating conditions that are suitable to chemically resolve semiconductor structures below 20 nm. Based on these results we propose workflows to speed up failure analysis by obtaining the analysis result directly in the FIB/SEM without the need for TEM analysis.     

Polymer‐Based Nitric Oxide Therapies: Recent Insights for Biomedical Applications

Since the discovery of nitric oxide (NO) in the 1980s, this cellular messenger has been shown to participate in diverse biological processes such as cardiovascular homeostasis, immune response, wound healing, bone metabolism, and neurotransmission. Its beneficial effects have prompted increased research in the past two decades, with a focus on the development of materials that can locally release NO. However, significant limitations arise when applying these materials to biomedical applications. This Feature Article focuses on the development of NO‐releasing and NO‐generating polymeric materials (2006–2011) with emphasis on recent in vivo applications. Results are compared and discussed in terms of NO dose, release kinetics, and biological effects, in order to provide a foundation to design and evaluate new NO therapies.     

A Possible Reaction Pathway to Fabricate a Half‐Metallic Wire on a Silicon Surface

Based on first‐principles electronic structure calculations and molecular dynamics simulations, a possible reaction pathway for fabricating half‐metallic Mo‐borine sandwich molecular wires on a hydrogen‐passivated Si(001) surface is presented. The molecular wire is chemically bonded to the silicon surface and is stable up to room temperature. Interestingly, the essential properties of the molecular wire are not significantly affected by the Si substrate. Furthermore, their electronic and magnetic properties are tunable by an external electric field, which allows the molecular wire to function as a molecular switch or a basic component for information storage devices, leading to applications in future molecular electronic and spintronic devices.     

Integrated PM Machine Design for an Aircraft EMA

This paper looks at the requirements and challenges of designing a permanent-magnet (PM) motor for a directly driven electromechanical actuator for aerospace applications. Having a directly driven system, the intermediate gearbox is eliminated, bringing advantages in terms of lower component count and reduced jamming probability. The design of a low-speed high pole number PM motor will be investigated as a potential solution. The main goals of the design are a high level of actuator integration in order to minimize weight and volume, fault tolerance, and high reliability. The design will be tailored to the requirements of a typical midspoiler actuation system for a large civil aircraft.      

Real-time management of telephone operating company networks:issues and approaches

The authors briefly overview the basic characteristics of legacy network management systems used in telephone operating companies (telcos) and highlight their deficiencies for the emerging network. They further propose a network management methodology for supporting both the embedded base and the new generation of network technologies and services. The proposed approach differs from earlier network management methodologies in three major ways: it is driven by managing service performance and network robustness, rather than managing network equipment; it is based on a global network model that makes “end-to-end” management possible, in contrast to today's highly segmented management; and its decision support and automated applications are “network-state” dependent as opposed to being solely driven by “raw” network measurements     

Biohybrid Carbon Nanotube/Agarose Fibers for Neural Tissue Engineering

We report a novel approach for producing carbon nanotube fibers (CNF) composed with the polysaccharide agarose. Current attempts to make CNF's require the use of a polymer or precipitating agent in the coagulating bath that may have negative effects in biomedical applications. We show that by taking advantage of the gelation properties of agarose one can substitute the bath with distilled water or ethanol and hence reduce the complexity associated with alternating the bath components or the use of organic solvents. We also demonstrate that these CNF can be chemically functionalized to express biological moieties through available free hydroxyl groups in agarose. We corroborate that agarose CNF are not only conductive and nontoxic, but their functionalization can facilitate cell attachment and response both in vitro and in vivo. Our findings suggest that agarose/CNT hybrid materials are excellent candidates for applications involving neural tissue engineering and biointerfacing with the nervous system.     

Effects of Millimeter Waves Radiation on Cell Membrane - A Brief Review

The millimeter waves (MMW) region of the electromagnetic spectrum, extending from 30 to 300 GHz in terms of frequency (corresponding to wavelengths from 10 mm to 1 mm), is officially used in non-invasive complementary medicine in many Eastern European countries against a variety of diseases such gastro duodenal ulcers, cardiovascular disorders, traumatism and tumor. On the other hand, besides technological applications in traffic and military systems, in the near future MMW will also find applications in high resolution and high-speed wireless communication technology. This has led to restoring interest in research on MMW induced biological effects. In this review emphasis has been given to the MMW-induced effects on cell membranes that are considered the major target for the interaction between MMW and biological systems.     

Enzyme Mimics for Engineered Biomimetic Cascade Nanoreactors: Mechanism,Applications, and Prospects

Multiple enzyme-driven biological catalytic cascades occur in living organisms, guiding highly efficient and selective transformations of substrates. Inspired by the merits of these biological catalytic cascade systems, enormous efforts have been devoted to developing novel cascade catalytic systems to mimic biological cascade catalytic reactions over the past few years. Nanozymes, a class of enzyme mimics, are nanomaterials with enzyme-like catalytic activity. The emergence and development of nanozymes has significantly advanced the development of biomimetic cascade nanoreactors. Currently, biomimetic cascade nanoreactors driven by advanced nanozymes have been widely used and exhibit many advantages such as superior cascade catalytic efficiency and high stability, resulting in significant advancements in biosensing and biomedical applications. The latest advances in understanding the cascade catalytic mechanism of nanozyme-engineered biomimetic cascade catalytic nanoreactors and their progressive applications for biosensing and biomedical applications are comprehensively covered here. First, nanozyme and enzyme/nanozyme-engineered biomimetic cascade catalytic nanoreactors are categorized according to their catalytic mechanism and properties. Then, the biosensing and biomedical applications, including cancer therapy, antibacterial activity, antioxidation, and hyperuricemia therapy of the cascade catalytic systems are covered. The conclusion describes the most important challenges and opportunities remaining in this exciting area of research.     

Universal Approach to Rapid Amplified Plasmonic Sensing Using Helix Defect Phase Transition Polymers

Permittivity sensing is a critically important analytical tool for bioscience, environmental, and industrial applications. The response time for commonly used plasmonic permittivity sensors is fundamentally set by the reaction kinetics of chemically adsorbed analytes. In this work, the proposal is to overcome this limit by combining plasmonic sensors with phase transition materials possessing a rapid amplified electrostatic response such as quadrupole moment induced molecular helix reversal. As a proof-of-concept, rapid sensing of CO₂ on a phase transition polytetrafluoroethylene substrate and amplification of permittivity response in plasmonic Fabry–Perot sensor is shown. The demonstrated universal approach holds promise for a wide range of applications in fast, real time sensing and monitoring of biological and environmental processes.     

Electrical conductivity imaging via contactless measurements: an experimental study

A data-acquisition system has been developed to image electrical conductivity of biological tissues via contactless measurements. This system uses magnetic excitation to induce currents inside the body and measures the resulting magnetic fields. The data-acquisition system is constructed using a PC-controlled lock-in amplifier instrument. A magnetically coupled differential coil is used to scan conducting phantoms by a computer controlled scanning system. A 10000-turn differential coil system with circular receiver coils of radii 15 mm is used as a magnetic sensor. The transmitter coil is a 100-turn circular coil of radius 15 mm and is driven by a sinusoidal current of 200 mA (peak). The linearity of the system is 7.2% full scale. The sensitivity of the system to conducting tubes when the sensor-body distance is 0.3 cm is 21.47 mV/(S/m). It is observed that it is possible to detect a conducting tube of average conductivity (0.2 S/m) when the body is 6 cm from the sensor. The system has a signal-to-noise ratio of 34 dB and thermal stability of 33.4 mV/degrees C. Conductivity images are reconstructed using the steepest-descent algorithm. Images obtained from isolated conducting tubes show that it is possible to distinguish two tubes separated 17 mm from each other. The images of different phantoms are found to be a good representation of the actual conductivity distribution. The field profiles obtained by scanning a biological tissue show the potential of this methodology for clinical applications.     

Is there a Biological Basis for Therapeutic Applications of Millimetre Waves and THz Waves?

Millimetre wave (MMW) and THz wave (THz) applications are already employed in certain industrial and medical environments for non-destructive quality control, and medical imaging, diagnosis, and therapy, respectively. The aim of the present study is to investigate if published experimental studies (in vivo and in vitro) provide evidence for “non-thermal” biological effects of MMW and THz. Such effects would occur in absence of tissue heating and associated damage and are the ones that can be exploited for therapeutic medical use. The investigated studies provide some evidence for both MMW and THz that can influence biological systems in a manner that is not obviously driven by tissue heating. However, the number of relevant studies is very limited which severely limits the drawing of any far-reaching conclusions. Furthermore, the studies have not addressed specific interaction mechanisms and do not provide hints for future mechanistic studies. Also, the studies do not indicate any specific importance regarding power density levels, frequencies, or exposure duration. It is also unclear if any specific biological endpoints are especially sensitive. Any therapeutic potential of MMW or THz has to be evaluated based on future high-quality studies dealing with physical, bio-physical, and biological aspects that have specific health-related perspectives in mind.     

Error and congestion control for wireless sensor networks

In the wireless sensors network (WSN) field, a wide variety of sensors produce a heterogeneous traffic mix, targeting diverse applications with different reliability requirements. We focus on emergency response scenarios, where a mobile rescuer moves through a, possibly disconnected, network, trying to talk to diverse sensors. We assume two types of sensors, event sensors triggered by an event and periodic sensors activated at predefined time intervals, as well as two types of transmission, either using the highest bit rate available or using predefined bit rates. Our reliable transport protocol for sensor networks with mobile sinks (RT‐SENMOS) takes into account all these parameters and tries to provide the best possible user experience under the current circumstances of the network, using a sink‐driven approach where an application‐specific sink is combined with generic sensors. RT‐SENMOS was implemented and tested over a real network with emulated losses and compared against rate‐controlled reliable transport (RCRT), a well‐known sink‐driven protocol. The results show that RT‐SENMOS fully exploits the available bandwidth in all cases, while RCRT only manages to exploit 60% to 90% of it. Furthermore, RT‐SENMOS adapts much faster to prevailing network conditions, while its protocol overhead, in terms of control messages exchanged, is much lower than that of RCRT.