In this review a strategy for the design of bioinspired, smart, multiscale interfacial (BSMI) materials is presented and put into context with recent progress in the field of BSMI materials spanning natural to artificial to reversibly stimuli‐sensitive interfaces. BSMI materials that respond to single/dual/multiple external stimuli, e.g., light, pH, electrical fields, and so on, can switch reversibly between two entirely opposite properties. This article utilizes hydrophobicity and hydrophilicity as an example to demonstrate the feasibility of the design strategy, which may also be extended to other properties, for example, conductor/insulator, p‐type/n‐type semiconductor, or ferromagnetism/anti‐ferromagnetism, for the design of other BSMI materials in the future.

We have demonstrated a novel sensing strategy employing single-stranded probe DNA, unmodified gold nanoparticles, and a positively charged, water-soluble conjugated polyelectrolyte to detect a broad range of targets including nucleic acid (DNA) sequences, proteins, small molecules, and inorganic ions. This nearly "universal" biosensor approach is based on the observation that, while the conjugated polyelectrolyte specifically inhibits the ability of single-stranded DNA to prevent the aggregation of gold-nanoparticles, no such inhibition is observed with double-stranded or otherwise "folded" DNA structures. Colorimetric assays employing this mechanism for the detection of hybridization are sensitive and convenient-picomolar concentrations of target DNA are readily detected with the naked eye, and the sensor works even when challenged with complex sample matrices such as blood serum. Likewise, by employing the binding-induced folding or association of aptamers we have generalized the approach to the specific and convenient detection of proteins, small molecules, and inorganic ions. Finally, this new biosensor approach is quite straightforward and can be completed in minutes without significant equipment or training overhead.biosensor | aptamer | visual detection | thrombin detection | cocaine detection G old nanoparticle colorimetric biosensors have seen significant applications in diagnostics, environmental monitoring, and antibioterrorism supporting unaided, visual readout (1-12). Commonly, the relevant nanoparticles are covalently modified with either a probe DNA or an aptamer such that hybridization (13-16) or aptamer-target interactions (17-27), for example the scanometric method developed by Mirkin (25), which is a very sensitive and specific tool, crosslink them, inducing aggregation. The second broad approach utilizes unmodified nanoparticles. (28-30) These two approaches, however, suffer from timeconsuming (20-40 h of assembly) and relatively poor (low nanomolar) detection limits, respectively. Here, a unique, colorimetric sensing strategy employing a simple but selective combination of a single-stranded DNA probe, a positively charged, water-soluble conjugated polyelectrolyte, and unmodified gold nanoparticles is demonstrated. The universality of this method allows detection of a broad range of targets, including nucleic acid (DNA) sequences, proteins, small molecules, and ino rganic ions. Our approach is rapid (turnaround time is 5-10 min) and sensitive (picomolar concentrations of target DNA are readily detected with the naked eye, even in complex sample matrices like blood serum). Hence, an operator with minimum scientific overhead can easily employ this technique.Generally, the gold nanoparticle applications typically rely on a quantitative coupling between target recognition and the aggregation of the nanoparticles, which, in turn, leads to a dramatic change in the photonic properties-and thus the color-of the nanoparticle solution. This colorimetric "readout" avoids the relative complexity inherent...

A limitation of many traditional approaches to the detection of specific oligonucleotide sequences, such as molecular beacons, is that each target strand hybridizes with (and thus activates) only a single copy of the relevant probe sequence. This 1:1 hybridization ratio limits the gain of most approaches and thus their sensitivity. Here we demonstrate a nuclease-amplified DNA detection scheme in which exonuclease III is used to "recycle" target molecules, thus leading to greatly improved sensitivity relative to, for example, traditional molecular beacons without any significant restriction in the choice of target sequences. The exonuclease-amplified assay can detect target DNA at concentrations as low as 10 pM when performed at 37 degrees C, which represents a significant improvement over the equivalent molecular beacon alone. Moreover, at 4 degrees C we can obtain a detection limit as low as 20 aM, albeit at the cost of a 24 h incubation period. Finally, our assay can be easily interrogated with the naked eye and is thus amenable to deployment in the developing world, where fluorometric detection is more problematic.

The exponentially growing works on 2D materials have resulted in both high scientific interest and huge potential applications in nanocatalysis, optoelectronics, and spintronics. Of especial note is that the newly emerged and promising family of metal phosphorus trichalcogenides (MPX 3 ) contains semiconductors, metals, and insulators with intriguing layered structures and architectures. The bandgaps of the members in this family range from 1.3 to 3.5 eV, significantly enriching the application of 2D materials in the broad wavelength spectrum. In this review, emphasizing their remarkable structural, physicochemical, and magnetic properties, as well as the numerous applications in various fields, the innovative progress on layered MPX 3 crystals is summarized. Different from other layered materials, these crystals will advance a fascinating frontier in magnetism and spintronic devices with their especially featured atomic layered nanosheets. Thus, their crystal and electronic structures, along with some related researches in magnetism, are discussed in detail. The assortments of growth methods are then summarized. Considering their potential applications, the prominent utilization of these 2D MPX 3 nanoscrystals in catalysis, batteries, and optoelectronics is also discussed. Finally, the outlook of these kinds of layered nanomaterials is provided. Metal Phosphorus Trichalcogenidesions. Friedel [17] and Ferrand [18,19] discovered them in the late 1800s. Based on the interesting structure of these materials, significant research works were reported in the early 2000s. As expected, 2D MPX 3 phases share most of the abovementioned specific properties of 2D TMDs. According to the theoretical and experimental results, MPX 3 compounds are the most sought functional materials for their intermediate bandgaps ranging from 1.3 to 3.5 eV, [20,21] indicating their enhanced light absorption efficiency as compared to the TMD materials. In addition, their unusual intercalation-substitution or intercalation-reduction behavior as well as the incipient ionic conductivity promote their usage in Li-ion batteries, [22,23] gas storage, [24] and photo-electrochemical reactions. [25] Unlike TMDs, several MPX 3 materials show intrinsic anti-ferromagnetism below the Neel temperatures of 78 K for MnPS 3 , 116 K for FePS 3 , and 155 K for NiPS 3 . [26,27] Recently, Li et al. [28] predicted that transformation from the anti-ferromagnetism to ferromagnetism for exfoliated MnPSe 3 nanosheet will be reduced by carrier doping. And the Monte Carlo simulation reveals the Curie temperature of the doped MnPSe 3 nanosheets can reach 206 K, rendering it with potential for utilizations in spintronic devices at high temperature. Therefore, the members in the MPX 3 family have the abovementioned properties along with structural flexibility stemming from their van der Waals nature; thus, it is reasonable to assume that they will contribute to the next major frontier in 2D vdW layered materials.Herein, we emphasize on reviewing the impressive recent progress...

Switchable ion channels that are made of membrane proteins play different roles in cellular circuits. Since gating nanopore channels made of proteins can only work in the environment of lipid membrane, they are not fully compatible to the application requirement as a component of those nanodevice systems in which lipid membranes are hard to establish. Here we report a synthetic nanopore-DNA system where single solid-state conical nanopores can be reversibly gated by switching DNA motors immobilized inside the nanopores. High- (on-state) and low- (off-state) conductance states were found within this nanopore-DNA system corresponding to the single-stranded and i-motif structures of the attached DNA motors. The highest gating efficiency indicated as current ratio of on-state versus off-state was found when the length of the attached DNA molecule matched the tip diameter of the nanopore well. This novel nanopore-DNA system, which was gated by collective folding of structured DNA molecules responding to the external stimulus, provided an artificial counterpart of switchable protein-made nanopore channels. The concept of this DNA motor-driven nanopore switch can be used to build novel, biologically inspired nanopore machines with more precisely controlled functions in the near future by replacing the DNA molecules with other functional biomolecules, such as polypeptides or protein enzymes.

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.

In general, superhydrophobic surfaces [1,2] with a water contact angle (CA) greater than 150°can be obtained by controlling the topography of hydrophobic surfaces, while superhydrophilic surfaces with a CA of about 0°can be realized through a three-dimensional (3D) [3] or two-dimensional (2D) capillary effect [4] on hydrophilic surfaces. The surface roughness dramatically enhances the CA on the hydrophobic surface but decreases the CA on the hydrophilic surface owing to the capillary effect, which is consistent with Wenzel's equation. [5] The fundamental mechanism of these phenomenaproposes that a combination of a hierarchical micro/nanostructure is essential for superhydrophilicity/superhydrophobicity. Recently, with the development of the combination of responsive materials and surface roughness, [6,7] several thermally, pH, or optically responsive smart interfacial materials that can switch between superhydrophilicity and superhydrophobicity have been reported: for example, a temperature-responsive polymer poly(N-isopropyl acrylamide (PNIPAAm); [6] photoresponsive materials, such as ZnO, [8] spiropyram, [8] two-level-structured self-adaptive surfaces, [9] the photoswitched wettability on an electrostatic self-assembled monolayer; [8] and a reversible pH-responsive surface. [10] However, all of these surfaces [11,12] are responsive to only one kind of external stimuli, such as temperature, [6] light, [8] or pH. [10] To the best of our knowledge, a dual-responsive surface that switches between hydrophilic and hydrophobic has never been reported, to say nothing of a dual-responsive surface that switches between superhydrophilic and superhydrophobic.In this communication, a dual-stimuli-responsive surface with tunable wettability, reversible switching between superhydrophilicity and superhydrophobicity, and responsivity to both temperature (T) and pH, is reported. Such surfaces are obtained by simply fabricating a poly(N-isopropyl acrylamide-co-acrylic acid) [P(NIPAAm-co-AAc)] copolymer thin film on both a flat and a roughly etched silicon substrate. Reversible switching between superhydrophilicity and superhydrophobicity can be realized over both a narrow temperature range of about 10°C and over a relatively wide pH range of about 10. This dual-responsive property is a result of the combined effect of the chemical variation of the surface and the surface roughness. In contrast to the roughness-enhanced homo-PNIPAAm film that is only responsive to temperature, the dual responsivity of the P(NIPAAm-co-AAc) films is due to the effective addition of the pH-sensitive component, acrylic acid (AAc). In addition, the lower critical solubility temperature (LCST) of the copolymer is tunable with increasing pH.The copolymer P(NIPAAm-co-AAc) thin films are fabricated on both a flat and a rough silicon substrate by a typical surface-initiated atom transfer radical polymerization. [13] Compared with Figure 1a (left), which shows the flat substrate, Figure 1a (right) shows a typical scanning electron microscopy ...

Through rational design of a functional molecular probe with high sequence specificity that takes advantage of sensitive isothermal amplification with simple operation, we developed a one-pot hairpin-mediated quadratic enzymatic amplification strategy for microRNA (miRNA) detection. Our method exhibits ultrahigh sensitivity toward miR-21 with detection limits of 10 fM at 37 °C and 1 aM at 4 °C, which corresponds to nine strands of miR-21 in a 15 μL sample, and it is capable of distinguishing among miRNA family members. More importantly, the proposed approach is also sensitive and selective when applied to crude extractions from MCF-7 and PC3 cell lines and even patient tissues from intraductal carcinoma and invasive ductal carcinoma of the breast.