Multifarious Transit Gates for Programmable Delivery of Bio‐functionalized Matters

Programmable delivery of biological matter is indispensable for the massive arrays of individual objects in biochemical and biomedical applications. Although a digital manipulation of single cells has been implemented by the integrated circuits of micromagnetophoretic patterns with current wires, the complex fabrication process and multiple current operation steps restrict its practical application for biomolecule arrays. Here, a convenient approach using multifarious transit gates is proposed, for digital manipulation of biofunctionalized microrobotic particles that can pass through the local energy barriers by a time‐dependent pulsed magnetic field instead of multiple current wires. The multifarious transit gates including return, delay, and resistance linear gates, as well as dividing, reversed, and rectifying T‐junction gates, are investigated theoretically and experimentally for the programmable manipulation of microrobotic particles. The results demonstrate that, a suitable angle of the gating field at a suitable time zone is crucial to implement digital operations at integrated multifarious transit gates along bifurcation paths to trap microrobotic particles in specific apartments, paving the way for flexible on‐chip arrays of biomolecules and cells.     

On‐Chip Magnetic Platform for Single‐Particle Manipulation with Integrated Electrical Feedback

Methods for the manipulation of single magnetic particles have become very interesting, in particular for in vitro biological studies. Most of these studies require an external microscope to provide the operator with feedback for controlling the particle motion, thus preventing the use of magnetic particles in high‐throughput experiments. In this paper, a simple and compact system with integrated electrical feedback is presented, implementing in the very same device both the manipulation and detection of the transit of single particles. The proposed platform is based on zig‐zag shaped magnetic nanostructures, where transverse magnetic domain walls are pinned at the corners and attract magnetic particles in suspension. By applying suitable external magnetic fields, the domain walls move to the nearest corner, thus causing the step by step displacement of the particles along the nanostructure. The very same structure is also employed for detecting the bead transit. Indeed, the presence of the magnetic particle in suspension over the domain wall affects the depinning field required for its displacement. This characteristic field can be monitored through anisotropic magnetoresistance measurements, thus implementing an integrated electrical feedback of the bead transit. In particular, the individual manipulation and detection of single 1‐μm sized beads is demonstrated.     

Magnetic particles as markers and carriers of biomolecules

The detection and manipulation of biomolecules on a common platform is of considerable interest not only for application in devices such as diagnostic tools but also for basic research in biological and medical systems. A promising approach is the utilisation of magnetic particles as markers and carriers for biomolecules. The principle functionality of this approach is demonstrated by the authors. Magnetic particles used as markers can be detected by highly sensitive magnetoresistive sensors resulting in a purely electronic signal. A direct comparison with the standard fluorescence method reveals the advantages of using the magnetic particles. In addition, magnetic particles used as carriers can be manipulated on-chip via currents running through especially designed line patterns. Some current drawbacks and future aspects are discussed. The combination of sensing and manipulating magnetic particles is a promising choice for future integrated lab-on-a-chip systems.     

Charge Transport in 2D DNA Tunnel Junction Diodes

Recently, deoxyribonucleic acid (DNA) is studied for electronics due to its intrinsic benefits such as its natural plenitude, biodegradability, biofunctionality, and low‐cost. However, its applications are limited to passive components because of inherent insulating properties. In this report, a metal–insulator–metal tunnel diode with Au/DNA/NiO_x junctions is presented. Through the self‐aligning process of DNA molecules, a 2D DNA nanosheet is synthesized and used as a tunneling barrier, and semitransparent conducting oxide (NiO_x) is applied as a top electrode for resolving metal penetration issues. This molecular device successfully operates as a nonresonant tunneling diode, and temperature‐variable current–voltage analysis proves that Fowler–Nordheim tunneling is a dominant conduction mechanism at the junctions. DNA‐based tunneling devices appear to be promising prototypes for nanoelectronics using biomolecules.     

Interfacially Polymerized Particles with Heterostructured Nanopores for Glycopeptide Separation

Porous polymer materials are extensively used for biomolecule separation. However, conventional homogeneous porous polymer materials cannot efficiently separate specific low‐abundance biomolecules from complex samples. Here, particles fabricated by emulsion interfacial polymerization featuring heterostructured nanopores with tunable size are reported, which can be used to realize low‐abundance glycopeptide (GP) separation from complex biofluids. The heterostructured surface inside the nanopores allows solvent‐dependent local adsorption of biomolecules onto hydrophilic or hydrophobic regions. Low‐abundance hydrophilic GPs in complex biofluids can be efficiently separated via the hydrophilic region of nanopores in low‐polarity solvent after the hydrophobic region removes high‐abundance hydrophobic proteins and non‐glycopeptides in high‐polarity solvent. It is expected that these particles with heterostructured nanopores can be used for separation of nucleic acids, saccharides, and proteins, and downstream clinical diagnosis.     

Laser‐Ignited Relay‐Domino‐Like Reactions in Graphene Oxide/CL‐20 Films for High‐Temperature Pulse Preparation of Bi‐Layered Photothermal Membranes

Light‐ignited combustions have been proposed for a variety of industrial and scientific applications. They suffer, however, from ultrahigh light ignition thresholds and poor self‐propagating combustion of typical high‐energy density materials, e.g., 2,4,6,8,10,12‐(hexanitrohexaaza)cyclododecane (CL‐20). Here, reported is that both light ignition and combustion performance of CL‐20 are greatly enhanced by embedding ε‐CL‐20 particles in a graphene oxide (GO) matrix. The GO matrix yields a drastic temperature rise that is sufficient to trigger the combustion of GO/CL‐20 under low laser irradiation (35.6 mJ) with only 6 wt% of GO. The domino‐like reduction‐combustion of the GO matrix can serve as a relay and deliver the decomposition‐combustion of CL‐20 to its neighbor sites, forming a relay‐domino‐like reaction. In particular, a synergistic reaction between GO and CL‐20 occurrs, facilitating more energy release of the GO/CL‐20 composite. The novel relay‐domino‐like reaction coupled with the synergistic reaction of CL‐20 and GO results in a deflagration of the material, which generates a high‐temperature pulse (HTP) that can be guided to produce advanced functional materials. As a proof of concept, a bi‐layered photothermal membrane is prepared by HTP treatment in an extremely simple and fast way, which can serve as a model architecture for efficient interfacial water evaporation.     

Biocomputing with Nanostructures on Lipid Bilayers

Biocomputation is the algorithmic manipulation of biomolecules. Nanostructures, most notably DNA nanostructures and nanoparticles, become active substrates for biocomputation when modified with stimuli‐responsive, programmable biomolecular ligands. This approach—biocomputing with nanostructures (“nano‐bio computing”)—allows autonomous control of matter and information at the nanoscale; their dynamic assemblies and beneficial properties can be directed without human intervention. Recently, lipid bilayers interfaced with nanostructures have emerged as a new biocomputing platform. This new nano‐bio interface, which exploits lipid bilayers as a chemical circuit board for information processing, offers a unique reaction space for realizing nanostructure‐based computation at a previously unexplored dimension. In this Concept, recent advances in nano‐bio computing are briefly reviewed and the newly emerging concept of biocomputing with nanostructures on lipid bilayers is introduced.     

A Lithography‐Free and Field‐Programmable Photonic Metacanvas

The unique correspondence between mathematical operators and photonic elements in wave optics enables quantitative analysis of light manipulation with individual optical devices. Phase‐transition materials are able to provide real‐time reconfigurability of these devices, which would create new optical functionalities via (re)compilation of photonic operators, as those achieved in other fields such as field‐programmable gate arrays (FPGA). Here, by exploiting the hysteretic phase transition of vanadium dioxide, an all‐solid, rewritable metacanvas on which nearly arbitrary photonic devices can be rapidly and repeatedly written and erased is presented. The writing is performed with a low‐power laser and the entire process stays below 90 °C. Using the metacanvas, dynamic manipulation of optical waves is demonstrated for light propagation, polarization, and reconstruction. The metacanvas supports physical (re)compilation of photonic operators akin to that of FPGA, opening up possibilities where photonic elements can be field programmed to deliver complex, system‐level functionalities.     

Nanopore Sensing in Aqueous Two‐Phase System: Simultaneous Enhancement of Signal and Translocation Time via Conformal Coating

Nanofluidic resistive pulse sensing (RPS) has been extensively used to measure the size, concentration, and surface charge of nanoparticles in electrically conducting solutions. Although various methods have been explored for improving detection performances, intrinsic problems including the extremely low particle‐to‐pore volume ratio (<0.01%) and fast nanoparticle translocation (10–1000 µs) still induce difficulties in detection, such as low signal magnitudes and short translocation times. Herein, we present an aqueous two‐phase system (ATPS) in a nanofluidic RPS for amplifying translocation signals and decreasing translocation speeds simultaneously. Two immiscible aqueous liquids build a liquid‐liquid interface inside nanopores. As particles translocate from a high‐affinity liquid phase into a lower‐affinity one, the high‐affinity liquid forms a conformal coating on the particles, which increases the effective particle size and amplifies the current‐blockage signal. The translocation time is also increased, as the ATPS interface impedes the particle translocation. For 20 nm particles, 7.92‐fold and 5.82‐fold enhancements of signal magnitude and translocation time can be achieved. To our knowledge, this is the first attempt to improve nanofluidic RPS by treating an interface of solution reservoirs for manipulating target particles rather than nanopores. This direct particle manipulation allows us to solve the two intrinsic problems all at once.     

From an Organometallic Monolayer to an Organic Monolayer Covered by Metal Nanoislands: A Simple Thermal Protocol for the Fabrication of the Top Contact Electrode in Molecular Electronic Devices

In this contribution, a novel method for practical uses in the fabrication of the top contact electrode in a metal/organic monolayer/metal device is presented. The procedure involves the thermally induced decomposition of an organometallic compound, abbreviated as the TIDOC method. Monolayers incorporating the metal organic compounds (MOCs) [[4‐{(4‐carboxy)ethynyl}phenyl]ethynyl]‐(triphenylphosphine)‐gold, 1, or [1‐isocyano‐4‐methoxybenzene]‐[4‐amino‐phenylethynyl]‐gold, 2, were annealed at moderate temperatures (1: 150 °C for 2h and 2: 100 °C for 2 h), resulting in cleavage of the Au‐P or Au‐C bond and reduction of Au(I) to Au(0) as metallic gold nanoparticles (GNPs). These particles are distributed on the surface of the film resulting in formation of metal/molecule/GNP sandwich structures. Electrical properties of these nascent devices were determined by recording I–V curves with a conductive‐AFM. The I–V curves collected from these metal/organic monolayer/GNPs sandwich structures are typical of metal‐molecule‐metal junctions, with no low resistance traces characteristic of metallic short circuits observed over a wide range of set‐point forces. The TIDOC method is therefore an effective procedure for the fabrication of molecular junctions for the emerging area of molecular electronics.     

A Microfabricated Sandwiching Assay for Nanoliter and High‐Throughput Biomarker Screening

Cells secrete substances that are essential to the understanding of numerous immunological phenomena and are extensively used in clinical diagnoses. Countless techniques for screening of biomarker secretion in living cells have generated valuable information on cell function and physiology, but low volume and real‐time analysis is a bottleneck for a range of approaches. Here, a simple, highly sensitive assay using a high‐throughput micropillar and microwell array chip (MIMIC) platform is presented for monitoring of biomarkers secreted by cancer cells. The sensing element is a micropillar array that uses the enzyme‐linked immunosorbent assay (ELISA) mechanism to detect captured biomolecules. When integrated with a microwell array where few cells are localized, interleukin 8 (IL‐8) secretion can be monitored with nanoliter volume using multiple micropillar arrays. The trend of cell secretions measured using MIMICs matches the results from conventional ELISA well while it requires orders of magnitude less cells and volumes. Moreover, the proposed MIMIC is examined to be used as a drug screening platform by delivering drugs using micropillar arrays in combination with a microfluidic system and then detecting biomolecules from cells as exposed to drugs.     

In‐Plane Isotropic/Anisotropic 2D van der Waals Heterostructures for Future Devices

Mono‐ to few‐layers of 2D semiconducting materials have uniquely inherent optical, electronic, and magnetic properties that make them ideal for probing fundamental scientific phenomena up to the 2D quantum limit and exploring their emerging technological applications. This Review focuses on the fundamental optoelectronic studies and potential applications of in‐plane isotropic/anisotropic 2D semiconducting heterostructures. Strong light–matter interaction, reduced dimensionality, and dielectric screening in mono‐ to few‐layers of 2D semiconducting materials result in strong many‐body interactions, leading to the formation of robust quasiparticles such as excitons, trions, and biexcitons. An in‐plane isotropic nature leads to the quasi‐2D particles, whereas, an anisotropic nature leads to quasi‐1D particles. Hence, in‐plane isotropic/anisotropic 2D heterostructures lead to the formation of quasi‐1D/2D particle systems allowing for the manipulation of high binding energy quasi‐1D particle populations for use in a wide variety of applications. This Review emphasizes an exciting 1D–2D particles dynamic in such heterostructures and their potential for high‐performance photoemitters and exciton–polariton lasers. Moreover, their scopes are also broadened in thermoelectricity, piezoelectricity, photostriction, energy storage, hydrogen evolution reactions, and chemical sensor fields. The unique in‐plane isotropic/anisotropic 2D heterostructures may open the possibility of engineering smart devices in the nanodomain with complex opto‐electromechanical functions.     

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.     

Generation of High‐Order All‐Aqueous Emulsion Drops by Osmosis‐Driven Phase Separation

Droplets containing ternary mixtures can spontaneously phase‐separate into high‐order structures upon a change in composition, which provides an alternative strategy to form multiphase droplets. However, existing strategies always involve nonaqueous solvents that limit the potential applications of the resulting multiple droplets, such as encapsulation of biomolecules. Here, a robust approach to achieve high‐order emulsion drops with an all‐aqueous nature from two aqueous phases by osmosis‐induced phase separation on a microfluidic platform is presented. This technique is enabled by the existence of an interface of the two aqueous phases and phase separation caused by an osmolality difference between the two phases. The complexity of emulsion drops induced by phase separation could be controlled by varying the initial concentration of solutes and is systematically illustrated in a state diagram. In particular, this technique is utilized to successfully achieve high‐order all‐aqueous droplets in a different aqueous two‐phase system. The proposed method is simple since it only requires two initial aqueous solutions for generating multilayered, organic‐solvent‐free all‐aqueous emulsion drops, and thus these multiphase emulsion drops can be further tailored to serve as highly biocompatible material templates.     

Biopolymer Microparticles Prepared by Microfluidics for Biomedical Applications

Biopolymers are macromolecules that are derived from natural sources and have attractive properties for a plethora of biomedical applications due to their biocompatibility, biodegradability, low antigenicity, and high bioactivity. Microfluidics has emerged as a powerful approach for fabricating polymeric microparticles (MPs) with designed structures and compositions through precise manipulation of multiphasic flows at the microscale. The synergistic combination of materials chemistry afforded by biopolymers and precision provided by microfluidic capabilities make it possible to design engineered biopolymer‐based MPs with well‐defined physicochemical properties that are capable of enabling an efficient delivery of therapeutics, 3D culture of cells, and sensing of biomolecules. Here, an overview of microfluidic approaches is provided for the design and fabrication of functional MPs from three classes of biopolymers including polysaccharides, proteins, and microbial polymers, and their advances for biomedical applications are highlighted. An outlook into the future research on microfluidically‐produced biopolymer MPs for biomedical applications is also provided.     

Three‐Dimensional Exploration and Mechano‐Biophysical Analysis of the Inner Structure of Living Cells

A novel mechanobiological method is presented to explore qualitatively and quantitatively the inside of living biological cells in three dimensions, paving the way to sense intracellular changes during dynamic cellular processes. For this purpose, holographic optical tweezers, which allow the versatile manipulation of nanoscopic and microscopic particles by means of tailored light fields, are combined with self‐interference digital holographic microscopy. This biophotonic holographic workstation enables non‐contact, minimally invasive, flexible, high‐precision optical manipulation and accurate 3D tracking of probe particles that are incorporated by phagocytosis in cells, while simultaneously quantitatively phase imaging the cell morphology. In a first model experiment, internalized polystyrene microspheres with 1 μm diameter are three‐dimensionally moved and tracked in order to quantify distances within the intracellular volume with submicrometer accuracy. Results from investigations on cell swelling provoked by osmotic stimulation demonstrate the homogeneous stretching of the cytoskeleton network, and thus that the proposed method provides a new way for the quantitative 3D analysis of the dynamic intracellular morphology.     

Ultrafast Sodium Full Batteries Derived from X?Fe (X = Co,Ni, Mn) Prussian Blue Analogs

Exploring high‐rate electrode materials with excellent kinetic properties is imperative for advanced sodium‐storage systems. Herein, novel cubic‐like X? Fe (X = Co, Ni, Mn) Prussian blue analogs (PBAs), as cathodes materials, are obtained through as‐tuned ionic bonding, delivering improved crystallinity and homogeneous particles size. As expected, Ni‐Fe PBAs show a capacity of 81 mAh g^?1 at 1.0 A g^?1, mainly resulting from their physical–chemical stability, fast kinetics, and “zero‐strain” insertion characteristics. Considering that the combination of elements incorporated with carbon may increase the rate of ion transfer and improve the lifetime of cycling stability, they are expected to derive binary metal‐selenide/nitrogen‐doped carbon as anodes. Among them, binary Ni_0.67Fe_0.33Se₂ coming from Ni‐Fe PBAs shows obvious core–shell structure in a dual‐carbon matrix, leading to enhanced electron interactions, electrochemical activity, and “metal‐like” conductivity, which could retain an ultralong‐term stability of 375 mAh g^?1 after 10 000 loops even at 10.0 A g^?1. The corresponding full‐cell Ni‐Fe PBAs versus Ni_0.67Fe_0.33Se₂ deliver a remarkable Na‐storage capacity of 302.2 mAh g^?1 at 1.0 A g^?1. The rational strategy is anticipated to offer more possibilities for designing advanced electrode materials used in high‐performance sodium‐ion batteries.     

Pick‐and‐Place Assembly of Single Microtubules

Intracellular transport is affected by the filament network in the densely packed cytoplasm. Biophysical studies focusing on intracellular transport based on microtubule–kinesin system frequently use in vitro motility assays, which are performed either on individual microtubules or on random (or simple) microtubule networks. Assembling intricate networks with high flexibility requires the manipulation of 25 nm diameter microtubules individually, which can be achieved through the use of pick‐and‐place assembly. Although widely used to assemble tiny objects, pick‐and‐place is not a common practice for the manipulation of biological materials. Using the high‐level handling capabilities of microelectromechanical systems (MEMS) technology, tweezers are designed and fabricated to pick and place single microtubule filaments. Repeated picking and placing cycles provide a multilayered and multidirectional microtubule network even for different surface topographies. On‐demand assembly of microtubules forms crossings at desired angles for biophysical studies as well as complex networks that can be used as nanotransport systems.     

Nitrogen and Luminescent Nitrogen‐Vacancy Defects in Detonation Nanodiamond

An efficient method to investigate the microstructure and spatial distribution of nitrogen and nitrogen‐vacancy (N‐V) defects in detonation nanodiamond (DND) with primary particle sizes ranging from approximately 3 to 50 nm is presented. Detailed analysis reveals atomic nitrogen concentrations as high as 3 at% in 50% of diamond primary particles with sizes smaller than 6 nm. A non‐uniform distribution of nitrogen within larger primary DND particles is also presented, indicating a preference for location within the defective central part or at twin boundaries. A photoluminescence (PL) spectrum with well‐pronounced zero‐phonon lines related to the N‐V centers is demonstrated for the first time for electron‐irradiated and annealed DND particles at continuous laser excitation. Combined Raman and PL analysis of DND crystallites dispersed on a Si substrate leads to the conclusion that the observed N‐V luminescence originates from primary particles with sizes exceeding 30 nm. These findings demonstrate that by manipulation of the size/nitrogen content in DND there are prospects for mass production of nanodiamond photoemitters based on bright and stable luminescence from nitrogen‐related defects.     

Single particle X-ray diffractive imaging

In nanotechnology, strategies for the creation and manipulation of nanoparticles in the gas phase are critically important for surface modification and substrate-free characterization. Recent coherent diffractive imaging with intense femtosecond X-ray pulses has verified the capability of single-shot imaging of nanoscale objects at suboptical resolutions beyond the radiation-induced damage threshold. By intercepting electrospray-generated particles with a single 15 femtosecond soft-X-ray pulse, we demonstrate diffractive imaging of a nanoscale specimen in free flight for the first time, an important step toward imaging uncrystallized biomolecules.