Rational Strategy for Space-Confined Atomic Layer Deposition.

Atomic layer deposition (ALD) offers excellent controllability of spatial uniformity, film thickness at the Angstrom level, and film composition even for high-aspect-ratio nanostructured surfaces, which are rarely attainable by other conventional deposition methodologies. Although ALD has been successfully applied to various substrates under open-top circumstances, the applicability of ALD to confined spaces has been limited because of the inherent difficulty of supplying precursors into confined spaces. Here, we propose a rational methodology to apply ALD growths to confined spaces (meter-long microtubes with an aspect ratio of up to 10 000). The ALD system, which can generate differential pressures to confined spaces, was newly developed. By using this ALD system, it is possible to deposit TiOx layers onto the inner surface of capillary tubes with a length of 1000 mm and an inner diameter of 100 µm with spatial deposition uniformity. Furthermore, we show the superior thermal and chemical robustness of TiOx-coated capillary microtubes for molecular separations when compared to conventional molecule-coated capillary microtubes. Thus, the present rational strategy of space-confined ALD offers a useful approach to design the chemical and physical properties of the inner surfaces of various confined spaces.

Interfacial Molecular Compatibility for Programming Organic-Metal Oxide Superlattices.

Artificially programming a sequence of organic-metal oxide multilayers (superlattices) by using atomic layer deposition (ALD) is a fascinating and challenging issue in material chemistry. However, the complex chemical reactions between ALD precursors and organic layer surfaces have limited their applications for various material combinations. Here, we demonstrate the impact of interfacial molecular compatibility on the formation of organic-metal oxide superlattices using ALD. The effects of both organic and inorganic compositions on the metal oxide layer formation processes onto self-assembled monolayers (SAM) were examined by using scanning transmission electron microscopy, in situ quartz crystal microbalance measurements, and Fourier-transformed infrared spectroscopy. These series of experiments reveal that the terminal group of organic SAM molecules must satisfy two conflicting requirements, the first of which is to promptly react with ALD precursors and the second is not to bind strongly to the bottom metal oxide layers to avoid undesired SAM conformations. OH-terminated phosphate aliphatic molecules, which we have synthesized, were identified as one of the best candidates for such a purpose. Molecular compatibility between metal oxide precursors and the -OHs must be properly considered to form superlattices. In addition, it is also important to form densely packed and all-trans-like SAMs to maximize the surface density of reactive -OHs on the SAMs. Based on these design strategies for organic-metal oxide superlattices, we have successfully fabricated various superlattices composed of metal oxides (Al-, Hf-, Mg-, Sn-, Ti-, and Zr oxides) and their multilayered structures.

Clinical and Laboratory Characteristics in Children with Alagille Syndrome: Experience of a Single Center.

Background: This study aimed to explore the clinical predictors of Alagille syndrome (ALGS) in children and to provide a basis for early diagnosis. Methods: We retrospectively analyzed the clinical data of 14 children diagnosed with ALGS at the First People's Hospital of Lianyungang City from March 2016 to March 2021 and followed up the children. Results: Among the 14 patients, 9 (64.28%) had cholestasis, 12 (85.71%) had heart malformations, 13 (92.85%) had characteristic facial features, 2 (14.28%) had pruritus, and 2 (14.28%) had a positive family history. Among the 13 patients who were examined by pediatric ophthalmologists, 3 patients had ocular lesions. Among the 13 patients who underwent spine radiography, 2 had typical butterfly vertebrae. Among the 6 patients with hepatic pathology, 2 had intracellular cholestasis, 2 had reduced or no small bile duct in the portal area, 2 had small bile duct hyperplasia with massive fibrous hyperplasia and extensive inflammatory cell infiltration, and 2 underwent biliary tract exploration. Genetic testing of 12 children with ALGS revealed JAG1 gene mutations in 7 cases and NOTCH2 gene mutations in 2 cases. The abovementioned two mutant genes were not detected in any of the 3 cases. Among the 12 followed-up patients, 7 were in stable condition, 5 underwent liver transplantation, and 1 died of severe pneumonia. Conclusion: Cholestatic liver disease, cardiac malformations, and abnormal facial development are predictors of ALGS in children and can be definitively diagnosed by genetic testing.

Breath odor-based individual authentication by an artificial olfactory sensor system and machine learning.

Breath odor sensing-based individual authentication was conducted for the first time using an artificial olfactory sensor system. Using a 16-channel chemiresistive sensor array and machine learning, a mean accuracy of >97% was successfully achieved. The impact of the number of sensors on the accuracy and reproducibility was also demonstrated.

Correction: Breath odor-based individual authentication by an artificial olfactory sensor system and machine learning.

Correction for 'Breath odor-based individual authentication by an artificial olfactory sensor system and machine learning' by Chaiyanut Jirayupat et al., Chem. Commun., 2022, DOI: https://doi.org/10.1039/D1CC06384G.

Nanocellulose Paper Semiconductor with a 3D Network Structure and Its Nano-Micro-Macro Trans-Scale Design.

Semiconducting nanomaterials with 3D network structures exhibit various fascinating properties such as electrical conduction, high permeability, and large surface areas, which are beneficial for adsorption, separation, and sensing applications. However, research on these materials is substantially restricted by the limited trans-scalability of their structural design and tunability of electrical conductivity. To overcome this challenge, a pyrolyzed cellulose nanofiber paper (CNP) semiconductor with a 3D network structure is proposed. Its nano-micro-macro trans-scale structural design is achieved by a combination of iodine-mediated morphology-retaining pyrolysis with spatially controlled drying of a cellulose nanofiber dispersion and paper-crafting techniques, such as microembossing, origami, and kirigami. The electrical conduction of this semiconductor is widely and systematically tuned, via the temperature-controlled progressive pyrolysis of CNP, from insulating (1012 Ω cm) to quasimetallic (10-2 Ω cm), which considerably exceeds that attained in other previously reported nanomaterials with 3D networks. The pyrolyzed CNP semiconductor provides not only the tailorable functionality for applications ranging from water-vapor-selective sensors to enzymatic biofuel cell electrodes but also the designability of macroscopic device configurations for stretchable and wearable applications. This study provides a pathway to realize structurally and functionally designable semiconducting nanomaterials and all-nanocellulose semiconducting technology for diverse electronics.

Edge-Topological Regulation for in Situ Fabrication of Bridging Nanosensors.

In situ fabrication of well-defined bridging nanostructures is an interesting and unique approach to three-dimensionally design nanosensor structures, which are hardly attainable by other methods. Here, we demonstrate the significant effect of edge-topological regulation on in situ fabrication of ZnO bridging nanosensors. When employing seed layers with a sharp edge, which is a well-defined structure in conventional lithography, the bridging angles and electrical resistances between two opposing electrodes were randomly distributed. The stochastic nature of bridging growth direction at the sharp edges inherently causes such unintentional variation of structural and electrical properties. We propose an edgeless seed layer structure using a two-layers resist method to solve the above uncontrollability of bridging nanosensors. Such bridging nanosensors not only substantially improved the uniformity of structural and electrical properties between two opposing electrodes but also significantly enhanced the sensing responses for NO2 with the smaller variance and the lower limit of detection via in situ controlled electrical contacts.

Surface Dissociation Effect on Phosphonic Acid Self-Assembled Monolayer Formation on ZnO Nanowires.

Understanding the formation process of self-assembled monolayers (SAMs) of organophosphonic acids on ZnO surfaces is essential to designing their various applications, including solar cells, heterogeneous catalysts, and molecular sensors. Here, we report the significant effect of surface dissociation on SAM formation of organophosphonic acids on single-crystalline ZnO nanowire surfaces using infrared spectroscopy. When employing the most conventional solvent-methanol (relative permittivity εr = 32.6), the production of undesired byproducts (layered zinc compounds) on the surface was identified by infrared spectral data and microscopy. On the other hand, a well-defined SAM structure with a tridentate coordination of phosphonic acids on the surface was confirmed when employing toluene (εr = 2.379) or tert-butyl alcohol (εr = 11.22-11.50). The observation of layered zinc compounds as byproducts highlights that the degree of Zn2+ dissociation from the ZnO solid surface into a solvent significantly affects the surface coordination of phosphonic acids during the SAM formation process. Although the ZnO nanowire surface (m-plane) is hydrophilic, the present results suggest that a weaker solvent polarity is preferred to form well-defined phosphonic acid SAMs on ZnO nanowire surfaces without detrimental surface byproducts.

Water-Selective Nanostructured Dehumidifiers for Molecular Sensing Spaces.

Humidity and moisture effects, frequently called water poisoning, in surroundings are inevitable for various molecular sensing devices, strongly affecting their sensing characteristics. Here, we demonstrate a water-selective nanostructured dehumidifier composed of ZnO/TiO2/CaCl2 core-shell heterostructured nanowires for molecular sensing spaces. The fabricated nanostructured dehumidifier is highly water-selective without detrimental adsorptions of various volatile organic compound molecules and can be repeatedly operated. The thermally controllable and reversible dehydration process of CaCl2·nH2O thin nanolayers on hydrophilic ZnO/TiO2 nanowire surfaces plays a vital role in such water-selective and repeatable dehumidifying operations. Furthermore, the limitation of detection for sensing acetone and nonanal molecules in the presence of moisture (relative humidity ∼ 90%) was improved more than 20 times using nanocomposite sensors by operating the developed nanostructured dehumidifier. Thus, the proposed water-selective nanostructured dehumidifier offers a rational strategy and platform to overcome water poisoning issues for various molecular and gas sensors.

Mechanistic Approach for Long-Term Stability of a Polyethylene Glycol-Carbon Black Nanocomposite Sensor.

Polymer-carbon nanocomposite sensor is a promising molecular sensing device for electronic nose (e-nose) due to its printability, variety of polymer materials, and low operation temperature; however, the lack of stability in an air environment has been an inevitable issue. Here, we demonstrate a design concept for realizing long-term stability in a polyethylene glycol (PEG)-carbon black (CB) nanocomposite sensor by understanding the underlying phenomena that cause sensor degradation. Comparison of the sensing properties and infrared spectroscopy on the same device revealed that the oxidation-induced consumption of PEG is a crucial factor for the sensor degradation. According to the mechanism, we introduced an antioxidizing agent (i.e., ascorbic acid) into the PEG-CB nanocomposite sensor to suppress the PEG oxidation and successfully demonstrated the long-term stability of sensing properties under an air environment for 30 days, which had been difficult in conventional polymer-carbon nanocomposite sensors.

Nanowire-based sensor electronics for chemical and biological applications.

Detection and recognition of chemical and biological species via sensor electronics are important not only for various sensing applications but also for fundamental scientific understanding. In the past two decades, sensor devices using one-dimensional (1D) nanowires have emerged as promising and powerful platforms for electrical detection of chemical species and biologically relevant molecules due to their superior sensing performance, long-term stability, and ultra-low power consumption. This paper presents a comprehensive overview of the recent progress and achievements in 1D nanowire synthesis, working principles of nanowire-based sensors, and the applications of nanowire-based sensor electronics in chemical and biological analytes detection and recognition. In addition, some critical issues that hinder the practical applications of 1D nanowire-based sensor electronics, including device reproducibility and selectivity, stability, and power consumption, will be highlighted. Finally, challenges, perspectives, and opportunities for developing advanced and innovative nanowire-based sensor electronics in chemical and biological applications are featured.

Image Processing and Machine Learning for Automated Identification of Chemo-/Biomarkers in Chromatography-Mass Spectrometry.

We present a method named NPFimg, which automatically identifies multivariate chemo-/biomarker features of analytes in chromatography-mass spectrometry (MS) data by combining image processing and machine learning. NPFimg processes a two-dimensional MS map (m/z vs retention time) to discriminate analytes and identify and visualize the marker features. Our approach allows us to comprehensively characterize the signals in MS data without the conventional peak picking process, which suffers from false peak detections. The feasibility of marker identification is successfully demonstrated in case studies of aroma odor and human breath on gas chromatography-mass spectrometry (GC-MS) even at the parts per billion level. Comparison with the widely used XCMS shows the excellent reliability of NPFimg, in that it has lower error rates of signal acquisition and marker identification. In addition, we show the potential applicability of NPFimg to the untargeted metabolomics of human breath. While this study shows the limited applications, NPFimg is potentially applicable to data processing in diverse metabolomics/chemometrics using GC-MS and liquid chromatography-MS. NPFimg is available as open source on GitHub (http://github.com/poomcj/NPFimg) under the MIT license.

The impact of surface Cu2+ of ZnO/(Cu1-x Zn x )O heterostructured nanowires on the adsorption and chemical transformation of carbonyl compounds.

The surface cation composition of nanoscale metal oxides critically determines the properties of various functional chemical processes including inhomogeneous catalysts and molecular sensors. Here we employ a gradual modulation of cation composition on a ZnO/(Cu1-x Zn x )O heterostructured nanowire surface to study the effect of surface cation composition (Cu/Zn) on the adsorption and chemical transformation behaviors of volatile carbonyl compounds (nonanal: biomarker). Controlling cation diffusion at the ZnO(core)/CuO(shell) nanowire interface allows us to continuously manipulate the surface Cu/Zn ratio of ZnO/(Cu1-x Zn x )O heterostructured nanowires, while keeping the nanowire morphology. We found that surface exposed copper significantly suppresses the adsorption of nonanal, which is not consistent with our initial expectation since the Lewis acidity of Cu2+ is strong enough and comparable to that of Zn2+. In addition, an increase of the Cu/Zn ratio on the nanowire surface suppresses the aldol condensation reaction of nonanal. Surface spectroscopic analysis and theoretical simulations reveal that the nonanal molecules adsorbed at surface Cu2+ sites are not activated, and a coordination-saturated in-plane square geometry of surface Cu2+ is responsible for the observed weak molecular adsorption behaviors. This inactive surface Cu2+ well explains the mechanism of suppressed surface aldol condensation reactions by preventing the neighboring of activated nonanal molecules. We apply this tailored cation composition surface for electrical molecular sensing of nonanal and successfully demonstrate the improvements of durability and recovery time as a consequence of controlled surface molecular behaviors.

Enhanced Gas Sensing Properties of SnO2 Hollow Spheres Decorated with CeO2 Nanoparticles Heterostructure Composite Materials.

CeO2 decorated SnO2 hollow spheres were successfully synthesized via a two-step hydrothermal strategy. The morphology and structures of as-obtained CeO2/SnO2 composites were analyzed by various kinds of techniques. The SnO2 hollow spheres with uniform size around 300 nm were self-assembled with SnO2 nanoparticles and were hollow with a diameter of about 100 nm. The CeO2 nanoparticles on the surface of SnO2 hollow spheres could be clearly observed. X-ray photoelectron spectroscopy results confirmed the existence of Ce(3+) and the increased amount of both chemisorbed oxygen and oxygen vacancy after the CeO2 decorated. Compared with pure SnO2 hollow spheres, such composites revealed excellent enhanced sensing properties to ethanol. When the ethanol concentration was 100 ppm, the sensitivity of the CeO2/SnO2 composites was 37, which was 2.65-times higher than that of the primary SnO2 hollow spheres. The sensing mechanism of the enhanced gas sensing properties was also discussed.

Near-infrared fluorescence-based multiplex lateral flow immunoassay for the simultaneous detection of four antibiotic residue families in milk.

In this study, we developed a novel near-infrared fluorescence based multiplex lateral flow immunoassay by conjugating a near-infrared label to broad-specificity monoclonal antibody/receptor as detection complexes. Different antigens were dispensed onto separate test zones of nitrocellulose membrane to serve as capture reagents. This assay format allowed the simultaneous detection of four families of antibiotics (ß-lactams, tetracyclines, quinolones and sulfonamides) in milk within 20 min. Qualitative and quantitative analysis of target antibiotics were realized by imaging the fluorescence intensity of the near-infrared label captured on respective test lines. For qualitative analysis, the cut-off values of ß-lactams, tetracyclines, quinolones and sulfonamides were determined to be 8 ng/mL, 2 ng/mL, 4 ng/mL and 8 ng/mL respectively, which were much lower than the conventional gold nanoparticle based lateral flow immunoassay. For quantitative analysis, the detection ranges were 0.26-3.56 ng/mL for ß-lactams, 0.04-0.98 ng/mL for tetracyclines, 0.08-2.0 ng/mL for quinolones, and 0.1-3.98 ng/mL for sulfonamides, with linear correlation coefficients higher than 0.97. The mean spiked recoveries ranged from 93.7% to 108.2% with coefficient of variations less than 16.3%. These results demonstrated that this novel immunoassay is a promising approach for rapidly screening the four families of antibiotic residues in milk.

Hierarchical Assembly of α-Fe2O3 Nanosheets on SnO22Hollow Nanospheres with Enhanced Ethanol Sensing Properties.

We present the preparation of a hierarchical nanoheterostructure consisting of inner SnO2 hollow spheres (SHS) surrounded by an outer α-Fe2O3 nanosheet (FNS). Deposition of the FNS on the SHS outer surface was achieved by a facile microwave hydrothermal reaction to generate a double-shell SHS@FNS nanostructure. Such a composite with novel heterostructure acted as a sensing material for gas sensors. Significantly, the hierarchical composites exhibit excellent sensing performance toward ethanol, which is superior to the single component (SHS), mainly because of the synergistic effect and heterojunction.

Design of Au@ZnO yolk-shell nanospheres with enhanced gas sensing properties.

The Au@ZnO yolk-shell nanospheres with a distinctive core@void@shell configuration have been successfully synthesized by deposition of ZnO on Au@carbon nanospheres. Various techniques were employed for the characterization of the structure and morphology of as-obtained hybrid nanostructures. The results indicated that the Au@ZnO yolk-shell nanospheres have an average diameter of about 280 nm and the average thickness of the ZnO shell is ca. 40 nm. To demonstrate how such a unique structure might bring about more excellent gas sensing property, we carried out a comparison of the sensing performances of ZnO nanospheres with different inner structures. It was found that Au@ZnO yolk-shell nanospheres exhibited an obvious improvement in response to acetone compared with the pure ZnO nanospheres with hollow and solid inner structures. For instance, the response of the Au@ZnO nanospheres to 100 ppm acetone was about 37, which was about 2 (3) times higher than that of ZnO hollow (solid) nanostructures. The enhanced sensing properties were attributed to their unique microstructures (porous shell and internal voids) and the catalytic effect of the encapsulated Au nanoparticles.