A high-pressure resistant ternary network hydrogel based flexible strain sensor with a uniaxially oriented porous structure toward gait detection.

Gait abnormalities have been widely investigated in the diagnosis and treatment of neurodegenerative diseases. However, it is still a great challenge to achieve a comfortable, convenient, sensitive and high-pressure resistant flexible gait detection sensor for real-time health monitoring. In this work, a polyaniline (PANI)@(polyacrylic acid (PAA)-polyvinyl alcohol (PVA)) (PANI@(PVA-PAA)) ternary network hydrogel with a uniaxially oriented porous featured structure was successfully prepared using a simple freeze-thaw method and in situ polymerization. The PANI@(PVA-PAA) hydrogel shows excellent compressive mechanical properties (423.44 kPa), favorable conductivity (2.02 S m-1) and remarkable durability (500 loading-unloading cycle), and can sensitively detect the effect of pressure with a fast response time (200 ms). The PANI@(PVA-PAA) hydrogel assembled into a flexible sensor can effectively identify the movement state of the shoulder, knee and even the sole of the plantar for gait detection. The uniaxially oriented porous structure enables the hydrogel-based sensor to have a high rate of change in the longitudinal direction and can effectively distinguish various gaits. The construction of a hydrogen bond between PANI and the PVA-PAA hydrogel ensures the uniform distribution of PANI in the hydrogel to form a ternary network structure, which improves the pressure resistance and conductivity of the PANI@(PVA-PAA) hydrogel. Thus, PANI@(PVA-PAA) hydrogel flexible sensor for gait detection can not only effectively monitor some serious diseases but also detect some unscientific exercise in people's daily life.

Cell-membrane-targeted near-infrared fluorescent probe for detecting extracellular ATP.

Extracellular adenosine triphosphate (ATP) as a signal molecule plays a key role in tumor progression and metastasis. Therefore, the development of a fluorescent probe to detect extracellular ATP is crucial for tumor treatment. However, small-molecule fluorescent probes have better advantages than biological probes, such as low price, easy modification, and optical tunability, but still remain highly challenging and rarely explored in extracellular ATP detection. Here, a near-infrared small molecule fluorescent probe (NIR-P) with hydrophobic alkyl chains and hydrophilic macrocyclic polyamines was prepared for the detection of extracellular ATP. The NIR-P exhibited enhanced fluorescence upon binding to ATP by electrostatic interaction and π-π interaction between phosphates and macrocyclic polyamines, adenines and benzene rings with a limit of detection (LOD) of 21 nM. In addition, with similarity and intermiscibility to the cell membrane, the NIR-P can specifically target cell membranes and image extracellular ATP. This work provides a cell-membrane-targeted fluorescent probe used for extracellular ATP detection.

Three-dimensional MoS2-graphene aerogel nanocomposites for electrochemical sensing of quercetin.

A facile and novel electrochemical sensing platform is reported for quercetin determination with MoS2 nanoflowers-3D graphene aerogel (3D MoS2-GA) nanocomposite as signal amplified material. The 3D MoS2-GA nanocomposite was synthesized through a two-step hydrothermal method, in which MoS2 nanoflowers were prepared in advance. Characterizations of 3D MoS2-GA were performed by scanning electron microscopy, transmission electron microscopy, Raman spectroscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. The 3D MoS2-GA-modified glassy carbon electrode (3D MoS2-GA/GCE) was used to investigate the electrochemical behaviors of quercetin with electrochemical parameters calculated, reaction mechanism discussed, and experimental conditions optimized. Notably, the redox peak current densities of quercetin on 3D MoS2-GA/GCE raised 5.14 and 6.40 times compared with those on a bare GCE. Furthermore, a novel electroanalytical approach was proposed for the sensitive determination of quercetin within the concentration range 0.01 ~ 5.0 µmol/L, accompanied by a low detection limit of 0.0026 µmol/L (at a working potential of 0.38 V vs. Ag/AgCl). The recovery for practical sample analysis ranges from 97.0 to 105%, and the relative standard deviation is less than 4.2%. This established method shows reliable performance in determination of quercetin in tablets and urine samples.

Biomimetic Modification and In Vivo Safety Assessment of Superparamagnetic Iron Oxide Nanoparticles.

The efficacy of superparamagnetic iron oxide nanoparticles (SPIONs) for biomedical applications depends on the magnetic properties, long time stability in biological fluids, and specific targeting capacity. The properties of SPIONs were generally improved by surface modification, but common modification technologies were usually conducted with multi-steps under rigid conditions. In this work, a facile and simple approach to synthesize functionalized SPIONs contrast agents was set up. First of all, SPIONs were prepared by an improved ultrasonic co-precipitation method. Then the surfaces of these SPIONs were modified biomimeticly by dopamine (DA) with strong adhesion. At last, the c(RGDyK), a biomolecule with the capacity of specific targeting capacity towards liver tumor cells, were coupled with DA on SPIONs via Mannich reaction. Thus the novel magnetic composite nanoparticles (abbreviated as c(RGDyK)-PDA-SPIONs) were successfully prepared. The as-synthesized nanoparticles were characterized by scanning electron microscope (SEM), dynamic light scattering, magnetic hysteresis loop measuring instrument. As a result, that the c(RGDyK)-PDA-SPIONs had an average size of about 50 nm and uniform distribution, and had superparamagnetic properties, good water dispersion stability. The acute toxicity test of the assynthesized c(RGDyK)-PDA-SPIONs to mice was also investigated. It was observed that LD50 of c(RGDyK)-PDA-SPIONs was 4.38 g/kg, with a 95% confidence interval ranging from 3.49 g/kg to 5.87 g/kg. These results indicated the novel c(RGDyK)-PDA-SPIONs had excellent biocompatibility, which was endowed with a potential capacity to serve as MRI contrast agents in diagnosis and treatment of the liver tumor.

Gene expression profiling analysis of locus coeruleus in idiopathic Parkinson's disease by bioinformatics.

This study aimed to explore the underlying molecular mechanisms of idiopathic Parkinson's disease (IPD) by bioinformatics analysis. Gene expression profile GSE34516 was downloaded from the Gene Expression Omnibus. Eight locus coeruleus post-mortem tissue samples derived from four IPD patients and four neurological healthy controls were used to identify the differentially expressed genes (DEGs) by paired t test. Based on the DEGs, principal components were analyzed. The Gene Ontology functional and Kyoto Encyclopedia of Genes and Genomes pathway analysis of the genome microarray data were then performed. Finally, protein-protein interaction (PPI) network of the DEGs was constructed. Total 261 DEGs including 195 up-regulated and 66 down-regulated DEGs were identified. Intracellular protein transport and RNA splicing via transesterification reactions were selected as the most two significantly enriched functions. Mismatch repair, N-glycan biosynthesis, spliceosome and nucleotide excision repair were the significantly enriched pathways. In the PPI network, CTSS, CD53, IGSF6, PTPRC and LAPTM5 were the hub nodes. Intracellular protein transport and RNA splicing via transesterification reactions were closely associated with IPD. The DEGs, such as CX3CR1, SLC5A7, CD53 and PTPRC may be the potential targets for IPD diagnosis and treatment.

Triple-Responsive, Multimodal, Visual Electronic Skin toward All-in-One Health Management for Gestational Diabetes Mellitus.

Gestational diabetes mellitus (GDM) is one of the most common metabolic disorders during pregnancy, leading to serious complications for pregnant women and a threat to life safety of infants. Therefore, it is particularly important to establish a multipurpose monitoring pathway to important physiological indicators of pregnant women. In this work, three kinds of double network hydrogels are prepared with poly(vinyl alcohol) (PVA), borax, and cellulose ethers with varying substituents of methyl (methyl cellulose, MC), hydroxypropyl (hydroxypropyl cellulose, HPC), or both (hydroxypropyl methyl cellulose, HPMC), respectively. The corresponding toughness (143.9, 102.3, and 135.9 kJ cm-3) and conductivity (0.69, 0.45, and 0.51 S m-1) of the hydrogels demonstrate that PB-MC was endowed with the prominent performance. Molecular dynamics simulations further revealed the essence that hydrogen bond interactions between PVA and cellulose ethers play a critical role in regulating the structure and properties of hydrogels. Thermochromic capsule powders (TCPs) were subsequently doped in to achieve a composite hydrogel (TCPs@PB-MC) to indicate the change in human body temperature. Furthermore, the process of the TCPs@PB-MC response to glucose, pH, and temperature was tracked in-depth through the electrochemical window. This work provides a novel strategy for all-in-one health management of GDM.

Preparation of fluorescent polyurethane microspheres and their applications as reusable sensor for 4-nitrophenol detection and as microplastics model for visualizing polyurethane in cells and zebrafish.

Fluorescent microspheres are of significant interests due to their wide applications in biotechnology fields. However, their preparation presents several challenges, such as the need for dye labeling, the complexity of materials and often sophisticated preparation conditions. Here a simple process for hydrophilic and crosslinked polyurethane (CPU) microspheres, with carboxyl groups on the surface via one-step precipitation polymerization in 40 min, is presented. The microsphere size is easily adjusted by varying experimental conditions. CPU microspheres exhibit high thermal and pH stability with good redispersibility in water, and emit fluorescence without any modification or dye labeling. The emission mechanism is discussed. CPU microspheres are used as fluorescent probe to detect 4-nitrophenol (4-NP) based on their emission in UV light region, with excellent selectivity and sensitivity. In addition, they are reusable with detection limit unchanged after 7 cycles of reuses, a significant feature of this work. The mechanism of fluorescence detection is thoroughly explored and ascribed to the internal filtration effect. Based on the emission in visible light region, CPU microspheres are used as a model of PU microplastics (MPs) to visualize their biodistribution in HeLa and macrophage cells, as well as in zebrafish larvae, providing a reliable tracer for the visualization and tracking of PU MPs in organisms.

Easy regulation of chitosan-based hydrogel microstructure with citric acid as an efficient buffer.

Being an important soft material, the chitosan-based hydrogel exhibits colorful features and widespread applications stemmed mainly from its intrinsic microstructure. In particular, the design of hydrogels with oriented channel structures is of significance importance. In this paper, polyvinyl alcohol (PVA)/chitosan (CS)/MXene-CA hydrogels with directional channel structure were obtained by simple freezing and thawing method with citric acid (CA) as a buffer. The introduction of CS increased the tensile strength of PVA hydrogel from 5.38 kPa to 29.22 kPa. The uniform distribution of MXene was efficiently enhanced within the constructed channel microstructure, and conductivity was increased to 1.91 S/m. The response time of the flexible sensor based on the hydrogel was 200 ms. It can sensitively detect large-scale deformation (blending of joints), small-scale activity (frowning), and electrocardiogram. Therefore, the paper provided an efficient way to regulate the microstructure in hydrogel network and enhance the uniform dispersion of functional nanomaterials.

Metallic nanoparticles for catalytic reduction of toxic hexavalent chromium from aqueous medium: A state-of-the-art review.

The ever increasing concentration of toxic and carcinogenic hexavalent chromium (Cr (VI)) in various environmental mediums including water-bodies due to anthropogenic activities with rapid civilization and industrialization have become the major issue throughout the globe during last few decades. Therefore, developing new strategies for the treatment of Cr(VI) contaminated wastewaters are in great demand and have become a topical issue in academia and industry. To date, various techniques have been used for the remediation of Cr(VI) contaminated wastewaters including solvent extraction, adsorption, catalytic reduction, membrane filtration, biological treatment, coagulation, ion exchange and photo-catalytic reduction. Among these methods, the transformation of highly toxic Cr(VI) to benign Cr(III) catalyzed by metallic nanoparticles (M-NPs) with reductant has gained increasing attention in the past few years, and is considered to be an effective approach due to the superior catalytic performance of M-NPs. Thus, it is a timely topic to review this emerging technique for Cr(VI) reduction. Herein, recent development in synthesis of M-NPs based non-supported, supported, mono-, bi- and ternary M-NPs catalysts, their characterization and performance for the reduction of Cr(VI) to Cr(III) are reviewed. The role of supporting host to stabilize the M-NPs and leading to enhance the reduction of Cr(VI) are discussed. The Cr(VI) reduction mechanism, kinetics, and factors affecting the kinetics are overviewed to collect the wealthy kinetics data. Finally, the challenges and perspective in Cr(VI) reduction catalyzed by M-NPs are proposed. We believe that this review will assist the researchers who are working to develop novel M-NPs catalysts for the reduction of Cr(VI).

Comparisons of simple and complex coacervations for preparation of sprayable insect sex pheromone microcapsules and release control of the encapsulated pheromone molecule.

With dodecanol (C12OH) as a model molecule of insect sex pheromone as core material, natural polymers gelatin (GE) and acacia gum (AG) as wall materials, microcapsules aiming to be a sprayable environment-friendly pesticide were prepared via GE simple coacervation and complex coacervation of GE and AG. C12OH encapsulation in complex coacervation was higher than those in simple coacervation. Its encapsulation was enhanced with increase in wall material cross-linking. C12OH release revealed that samples from simple coacervation reached their end in 7 days, whereas those from complex coacervation manifested a quick release followed by a constant release. With increase in wall material cross-linking, the release was slowed down. SEM observation confirmed that core-shell morphology existed in the capsules.

Spreadable dispersion of insect sex pheromone capsules, preparation via complex coacervation and release control of the encapsulated pheromone component molecule.

Using insect female pheromone to disrupt their mating process is a new technology, which has been applied as environment friendly pesticides in agricultural and forestry industries to control pest infestation. Dodecanol (C(12)OH), as one of the simple pheromone component, was chosen and encapsulated as core material using gelatin (GE) and acacia gum (AG) as wall materials via complex coacervation. Through variations in capsule preparations, particularly the crosslinking density of the wall materials, release controllability of C(12)OH was studied. A series of C(12)OH-containing capsules were prepared with different concentrations of GE and AG and different crosslinkings. Crosslinking and C(12)OH encapsulation were enhanced when more crosslinker, either formaldehyde or glutaraldehyde, were used. At same level of crosslinker, lower crosslinking and higher C(12)OH encapsulation were obtained in microcapsules done with formaldehyde than those with glutaraldehyde. Constant release of C(12)OH was achieved in capsules prepared with glutaraldehyde. Mechanisms of C(12)OH release were discussed based on the results. Scanning electron microscopy was used to characterize the structure and morphology of the microcapsules, which seemingly confirmed existence of a core-shell structure in the capsules, with the coacervated polymers as the shell and C(12)OH the core.

Solvent annealing of PbI2 for the high-quality crystallization of perovskite films for solar cells with efficiencies exceeding 18.

While most work carried out to date has focused on the solvent annealing of perovskite, in the present work, we focused on the solvent annealing of lead iodide. Based on the two-step spin-coating method, we designed a screening method to search for an effective solvent annealing process for PbI2. PbI2 films were annealed in diverse solvent atmospheres, including DMF, DMSO, acetone, and isopropanol (IPA). We found that the solvent annealing of PbI2 in the DMF, acetone, and IPA atmospheres resulted in dense PbI2 films, which impeded the complete conversion of PbI2 to CH3NH3PbI3. Surprisingly, employing the DMSO solvent annealing process for PbI2 led to porous PbI2, which facilitated the complete conversion of PbI2 to perovskite with larger grain sizes. Solar cells fabricated using the DMSO solvent annealing process exhibited the best efficiency of 18.5%, with a fill factor of 76.5%. This unique solvent annealing method presents a new way of controlling the perovskite film quality for highly efficient solar cells.

Preparation and characterization of nanosized P(NIPAM-MBA) hydrogel particles and adsorption of bovine serum albumin on their surface.

Thermosensitive polymer hydrogel particles with size varying from 480 to 620 nm were prepared through precipitation copolymerization of N-isopropylacrylamide with N,N'-methylenebisacrylamide (MBA) in water with ammonium persulfate as the initiator. Only polymer hydrogels without any coagula were obtained when MBA concentration in the monomer mixture was kept between 2.5 and 10.0 wt%; with increased MBA concentration, the monomer conversion was enhanced, the size of the hydrogels was increased, and their shrinking was lessened when heated from 25°C to 40°C. Bovine serum albumin adsorption on the surface of the hydrogels of different MBA content was measured at different pH levels and under different temperatures. The results demonstrated that the adsorption of the protein on the hydrogels could be controlled by adjusting the pH, the temperature of adsorption, and the crosslinking in the hydrogels. The results were interpreted, and the mechanisms of the polymerization were proposed.