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Biomolecular markers, particularly circulating microRNAs (miRNAs) play an important role in diagnosis, monitoring, and therapeutic intervention of cancers. However, existing detection strategies remain intricate, laborious, and far from being developed for point-of-care testing. Here, we report a portable colorimetric sensor that utilizes the hetero-assembly of nanostructures driven by base pairing and recognition for direct detection of miRNAs. Following hybridization, two sizes of nanoparticles modified with single-strand DNA can be robustly assembled into heterostructures with strong optical resonance, exhibiting distinct structure colors. Particularly, the large nanoparticles are first arranged into nanochains to enhance scattering signals of small nanoparticles, which allows for sensitive detection and quantification of miRNAs without the requirement of target extraction, amplification, and fluorescent labels. Furthermore, we demonstrate the high specificity and single-base selectivity of testing different miRNA samples, which shows great potential in the diagnosis, staging, and monitoring of cancers. These heterogeneous assembled nanostructures provide an opportunity to develop simple, fast, and convenient tools for miRNAs detection, which is suitable for many scenarios, especially in low-resource setting.

SignificanceAdjusting the floating states when objects float on water shows great potential for assembly, mineral flotation, nanostructured construction, and floating robot design, but the real-time regulation of floating states is challenging. Inspired by the different floating states of a falling fruit, we propose a facile strategy to transform the object between different floating states based on a three-segment three-phase contact line evolution. In addition, the potential of floating state transformation in solar-powered water evaporation, interface catalysis, and drug delivery is demonstrated. These findings provide insights into floating regulation and show great potential for floating-related applications.

In nature, biological machines can perform sophisticated and subtle functions to maintain the metabolism of organisms. Inspired from these gorgeous works of nature, scientists have developed various artificial molecular motors and machines. However, selective transport of biomolecules across membrane has remained a great challenge. Here, we establish an ATP transport system by assembling photocontrolled DNA nanomachines into the artificial nanochannels. With alternant light irradiation, these ATP transport lines can selectively shepherd cargoes across the polymer membrane. These findings point to new opportunities for manipulating and improving the mass transportation and separation with light-controlled biomolecular motors, and can be used for other molecules and ions transmembrane transport powered by light.

The feather-like Ag@TiO2 nanostructures including 1-dimensional (1D) Ag nanowires and 2-dimensional (2D) TiO2 possess the features of fast electron transmission by one-dimensional metal nanomaterials, high light harvesting and electron collection by feather-like nanostructures like "plasmonic antenna" at the same time. We introduce them into photoanodes to enhance the conversion efficiency in DSSCs. The best efficiency (η) of the electrode reaches 8.16% compared with that of the pure TiO2 electrode (6.41%). The energy conversion efficiency and photocurrent density of photoanodes with Ag@TiO2 nanostructures are enhanced by about 14.5% and 27.8%, respectively, as compared with those of the pure TiO2 cells. The photoelectric properties of electrodes are investigated by optical and electrochemical measurements. Hence, the improved performances are attributed to the "plasmonic antenna" effect due to Ag@TiO2 anchored in TiO2 films.

Artificial single nanochannels have emerged as possible candidates for mimicking the process of ionic transport in ion channels and boosting the development of bioinspired intelligent nanomachines for real-world applications, such as biosensors, molecular filtration, and nanofluidic devices. One challenge that remains is to make the artificial nanochannel "smart", with various functions like an organism in Nature. The components of ion channels are asymmetrically distributed between membrane surfaces, which are significant for the implementation of the complex biological function. Inspired by this natural asymmetrical design, here we develop a biomimetic asymmetric responsive single nanochannel system that displays the advanced feature of providing control over pH- and temperature-tunable asymmetric ionic transport properties through asymmetric modifications inside the single nanochannels, which could be considered as a primal platform for the simulation of different ionic transport processes as well as the enhancement of the functionality of ion channels.

Herein we demonstrate a fully abiotic smart single-nanopore device that rectifies ionic current in response to the temperature. The temperature-responsive nanopore ionic rectifier can be switched between a rectifying state below 34 degrees C and a non-rectifying state above 38 degrees C actuated by the phase transition of the poly(N-isopropylacrylamide) [PNIPAM] brushes. On the rectifying state, the rectifying efficiency can be enhanced by the dehydration of the attached PNIPAM brushes below the LCST. When the PNIPAM brushes have sufficiently collapsed, the nanopore switches to the non-rectifying state. The concept of the temperature-responsive current rectification in chemically-modified nanopores paves a new way for controlling the preferential direction of the ion transport in nanofluidics by modulating the temperature, which has the potential to build novel nanomachines with smart fluidic communication functions for future lab-on-chip devices.

Learning from nature has inspired the creation of intelligent materials to better understand and imitate biology. Recent studies on bioinspired responsive surfaces that can switch between different states are shown, which open up new avenues for the development of smart materials in two dimensions. Based on this strategy, biomimetic nanochannel systems have been produced by introducing responsive molecules, which closely mimic the gating mechanism of biological nanochannels and show potential applications in many fields such as photoelectric-conversion systems demonstrated in this paper.

Potassium is especially crucial in modulating the activity of muscles and nerves whose cells have specialized ion channels for transporting potassium. Normal body function extremely depends on the regulation of potassium concentrations inside the ion channels within a certain range. For life science, undoubtedly, it is significant and challenging to study and imitate these processes happening in living organisms with a convenient artificial system. Here we report a novel biomimetic nanochannel system which has an ion concentration effect that provides a nonlinear response to potassium ion at the concentration ranging from 0 to 1500 microM. This new phenomenon is caused by the G-quadruplex DNA conformational change with a positive correlation with ion concentration. In this work, G-quadruplex DNA was immobilized onto a synthetic nanopore, which undergoes a potassium-responsive conformational change and then induces the change in the effective pore size. The responsive ability of this system can be regulated by the stability of G-quadruplex structure through adjusting potassium concentration. The situation of the grafting G-quadruplex DNA on a single nanopore can closely imitate the in vivo condition because the G-rich telomere overhang is attached to the chromosome. Therefore, this artificial system could promote a potential to conveniently study biomolecule conformational change in confined space by the current measurement, which is significantly different from the nanopore sequencing. Moreover, such a system may also potentially spark further experimental and theoretical efforts to simulate the process of ion transport in living organisms and can be further generalized to other more complicated functional molecules for the exploitation of novel bioinspired intelligent nanopore machines.

High-yield three-dimensional (3D) flower-like nanostructures self-assembled from 1 D ZnO nanorods and nanotubes are experimentally demonstrated. The Zn and O terminated crystal planes of ZnO nanorods results in positively and negatively charged top (001) and bottom (00-1) surfaces, respectively. The nanorods self-assembled into 3D nanostructures via the electrostatic interaction between the crystal planes with opposite charges. Moreover, on the basis of the different stability of polar and nonpolar planes in wurtzite-type ZnO, the nanorods based 3D nanostructures transformed into nanotubes based ones spontaneously. This provides a new approach to prepare multi-dimensional materials without the necessity to employ any external intervention.

Solution‐processed, high‐gain, and wavelength‐tunable perovskite single‐crystal microdisk (PVKsc‐MD) lasers have emerged as prospective coherent light sources in advanced nanophotonic designs. However, the inevitable multi‐directional emission from a highly symmetrical cavity leads to low light collection efficiency which greatly hinders its application in integrated optical circuits. Here, we report on surface‐patterned MAPbBr3 PVKsc‐MDs synthesized by a cost‐efficient bottom‐up solution process employing spin‐coating and confined‐growth nanoimprinting. The patterned microdisks have high crystal quality with regular shape and sharp edges and nano‐grating structure on the upper surface. This straightforward process yields surface‐patterned PVKsc‐MD lasers with a low lasing threshold and high quality (Q) factor. In addition, the grating structure patterned on the PVKsc‐MDs reduces the original symmetry of the laser cavity, which improves the emission directionality four times. [ABSTRACT FROM AUTHOR]

Patterned nanostructures with ultrasmall features endow functional devices with unique nanoconfinement and performance enhancements. The increasing demand for miniaturization has stimulated the development of sub‐100 nm nanopatterning techniques. Beyond conventional lithography—which is limited by unavoidable factors—advanced patterning techniques have been reported to produce nanoscale features down to molecular or even atomic scale. In this review, unconventional techniques for sub‐100 nm nanopatterning are discussed, in particular the principles by which to achieve the desired patterns (among other important issues). Such techniques can be classified into three categories: template‐replica, template‐induced, and template‐free techniques. Moreover, multi‐dimensional nanostructures consist of various building materials, the unique properties of which are summarized. Finally, the remaining challenges and opportunities for large‐scale patterning, the improvement of device performance, the multi‐dimensional nanostructures of biocompatible materials, molecular‐scale patterning, and the carbon footprint requirements for future nanofabrication processes are discussed. [ABSTRACT FROM AUTHOR]

A key issue of micro/nano devices is how to integrate micro/nanostructures with specified chemical components onto various curved surfaces. Hydrodynamic printing of micro/nanostructures on three‐dimensional curved surfaces is achieved with a strategy that combines template‐induced hydrodynamic printing and self‐assembly of nanoparticles (NPs). Non‐lithography flexible wall‐shaped templates are replicated with microscale features by dicing a trench‐shaped silicon wafer. Arising from the capillary pumped function between the template and curved substrates, NPs in the colloidal suspension self‐assemble into close‐packed micro/nanostructures without a gravity effect. Theoretical analysis with the lattice Boltzmann model reveals the fundamental principles of the hydrodynamic assembly process. Spiral linear structures achieved by two kinds of fluorescent NPs show non‐interfering photoluminescence properties, while the waveguide and photoluminescence are confirmed in 3D curved space. The printed multiconstituent micro/nanostructures with single‐NP resolution may serve as a general platform for optoelectronics beyond flat surfaces. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Systematical summary and discussion of colloidal PC sensors from materials, structures, and analysis methods. • MOF-based PCs, shape-memory polymer PCs, PCs composed of nature materials etc. are firstly summarized. • Hollow mesoporous PC, metastable PCs etc. are reviewed to emphasize the significance of structures in developing colloidal PC sensors. • PC sensor array for cross-reactive analysis system and time/spatial resolved reflection spectra are highlighted and discussed in details. • Firstly present 'time/spatial resolved reflection spectra' analysis method. Abstract Colloidal photonic crystal (PC) sensors have been well developed due to their unique advantages in preparation and functionalization, and have been applied into diverse sensing systems. Recently, many breakthroughs about new-type colloidal PC sensors with fast respond speed, high sensitivity and excellent selectivity have been achieved. In this review, we summarize the recent advances of colloidal PC sensors from aspects of materials, structures, and analysis methods, to exhibit the diverse developing strategies. Firstly, an overview of colloidal PC sensors composed of new responsive materials is presented. Next, the unique structures are systematically summarized according to their scale increasing from nanoscale to macroscale, including the colloidal nanoparticles with novel structures and morphologies, the micro-sized PC units, and the integrated PC devices. Then, two series of new analysis methods, cross-reactive analysis based on PC sensors and time/spatial resolved reflection spectra analysis, are highlighted and discussed in details because they can greatly improve the selectivity of recognitions. Finally, a summary and some perspectives on several development directions in this attractive research field are presented. [ABSTRACT FROM AUTHOR]

Abstract: The formation of polystyrene (PS) sphere nanostructures through vertical deposition can provide large surface roughness, which effectively enhances the hydrophobicity of the films. Moreover, well-ordered PS sphere arrays bring about structural colors, which can be controlled through the sphere diameter. All the water contact angles of colloidal crystal films prepared from monodisperse PS sphere solutions with diameters from 225 to 605 nm were larger than 120°, showing highly hydrophobic character. [Copyright &y& Elsevier]

The interfacial-dependent self-organization of a chiral amino acid amphiphile was observed on various substrates with different surface hydrophobicity. Three kinds of organizations are induced at different substrates, which appear as helical aggregates on hydrophobic surface (e.g. highly oriented pyrolytic graphite), molecular flat layer on hydrophilic surface, (e.g. mica) and a transition state between them on silicon wafer. The strength of the interactions between the helical aggregates formed in solution and the substrate is the key factor to the self-organization of the chiral molecule. The results reported here provide insight into how the surface hydrophobicity of substrates affects the self-organization of chiral molecules. [Copyright &y& Elsevier]