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The prepared Co(OH)2@Ti3C2Tx composite shows good gas sensing performance for ammonia at room temperature, making it a promising candidate for a practical detector for NH3.

Ammonia (NH

Herein, a fluorescence turn-on nanosensor (MnIO@pep-FITC) has been proposed for detecting trypsin activity in vitro and in vivo through covalently immobilizing an FITC modified peptide substrate of trypsin (pep-FITC) on manganese-doped iron oxide nanoparticle (MnIO NP) surfaces via a polyethylene glycol (PEG) crosslinker. The conjugation of pep-FITC with MnIO NPs results in the quenching of FITC fluorescence. After trypsin cleavage, the FITC moiety is released from the MnIO NP surface, leading to a remarkable recovery of FITC fluorescence signal. Under the optimum experimental conditions, the recovery ratio of FITC fluorescence intensity is linearly dependent on the trypsin concentration in the range of 2 to 100 ng mL−1 in buffer and intracellular trypsin in the lysate of 5 × 102 to 1 × 104 HCT116 cells per mL, respectively. The detection limit of trypsin is 0.6 ng mL−1 in buffer or 359 cells per mL HCT116 cell lysate. The MnIO@pep-FITC is successfully employed to noninvasively monitor trypsin activity in the ultrasmall (ca. 4.9 mm3 in volume) BALB/c nude mouse-bearing HCT116 tumor by in vivo fluorescence imaging with external magnetic field assistance, demonstrating that it has excellent practicability.

The self-assembly of metal-organic frameworks (MOFs) is crucial for the functional design of materials, including energy storage materials, catalysts, selective separation materials and optical crystals. However, oriented self-assembly of MOFs is still a challenge. Herein, we propose a novel strategy to drive oriented self-assembly of MOF polyhedral particles at the water-liquid interface by photoinitiated monomer polymerization. The MOF polyhedral particles self-assemble into ordered close-packed structures with obvious orientation in the polymer film, and the orientation is determined by the casting solvent on the water surface. The prepared large-area MOF polymer films show a Janus structure, containing a MOF monolayer and a polymer layer, and can be easily transferred to a variety of substrates. In addition, mixed MOF particles with different sizes and morphologies can also be assembled by this method. This novel method can be foreseen to provide a powerful driving force for the development of MOF self-assembly and to create more possibilities for utilizing the anisotropic properties of MOFs.

Metallic nanoparticles showed potent efficacy for diagnosis and therapy of cancer, but their clinical applications are limited by their poor tumor-targeting ability. Herein, peptide-functionalized 9 nm NaGdF4 nanoparticles (termed as, NaGdF4@bp-peptide NPs) have been synthesized through the Gd–phosphate coordination reaction of the spherical NaGdF4 nanoparticles with phosphopeptides (sequence: KLAKLAKKLAKLAKG(p-S)GAKRGARSTA, p-S means phosphorylated serine) including a p32 protein binding motif incorporating a cell-penetrating function, and a proapoptotic domain. The NaGdF4@bp-peptide NPs are ready to be efficiently internalized by cancer cells; they show a much higher cytotoxicity in MCF-7 breast cancer cells than the casein phosphopeptide (CPP) modified NaGdF4 nanoparticles (termed as, NaGdF4@CPP NPs). Using mouse-bearing MCF-7 breast cancer as a model system, the in vivo experimental results demonstrate that NaGdF4@bp-peptide NPs have integration of T1-weighted magnetic resonance imaging (MRI) contrast and tumor-targeting functionalities, and are able to suppress tumor growth without causing systemic toxicity.

Herein, a fluorescence turn-on nanosensor (MnIO@pep-FITC) has been proposed for detecting trypsin activity

Dietary acrylamide has attracted widespread concern due to its toxic effects; however, its adverse impact on the intestines is less assessed. Protein glycation of the Maillard-type is widely used for property modification, but its potential effect on preventive efficacy of protein digest against the acrylamide-induced intestinal barrier dysfunction is quite unknown. Caseinate was thus glycated with lactose. Two tryptic digests from the glycated caseinate and untreated caseinate (namely GCN digest and CN digest) were then assessed for their protective effects against acrylamide-induced intestinal barrier dysfunction in the IEC-6 cell model. The results showed that acrylamide at 1.25–10 mmol L−1 dose-dependently had cytotoxic effects on IEC-6 cells, leading to decreased cell viability and increased lactate dehydrogenase release. Acrylamide also brought about barrier dysfunction, including decreased trans-epithelial electrical resistance (TEER) value and increased epithelial permeability. However, the two digests at 12.5–100 μg mL−1 could alleviate this dysfunction via enhancing cell viability by 70.2–83.9%, partly restoring TEER values, and decreasing epithelial permeability from 100% to 76.6–94.1%. The two digests at 25 μg mL−1 strengthened the tight junctions via increasing tight junction proteins ZO-1, occludin, and claudin-1 expression by 11.5–68.6%. However, the results also suggested that the GCN digest always showed lower protective efficacy than the CN digest in the cells. It is concluded that Maillard-type caseinate glycation with lactose endows the resultant tryptic digest with impaired preventive effect against acrylamide-induced intestinal barrier dysfunction, highlighting another adverse effect of the Maillard reaction on food proteins.

As the new representative in the carbonaceous family, carbon dots (CDs) have gained remarkable research interests over the past decade. Herein, we report the facile preparation and thorough performance comparison of three types of carbon dots with the adoption of ubiquitous natural fruit juice as precursors and demonstrate their application in pH sensing, patterning and bioimaging. All the yielded CDs show interesting optical properties including evident single- or two-photon absorption and excitation-dependent photoluminescence along with the high fluorescent yield. A detailed study on the physical properties by EPR and Stokes shift analysis and structural composition analysis by XPS and Raman spectroscopy suggest that the fluorescence of CDs originates from the electron–hole recombination via the defect state. In addition, through the regulation of non-radiative recombination rate of CDs, all the obtained CDs could be applied as fluorescent sensing platforms toward the sensitive detection of the solution pH changes by the indication of CDs' fluorescent yield and lifetime variation. Moreover, it was also proven that the resulting CDs could be employed as fluorescent inks for printing patterns in anti-counterfeit applications and as fluorescent probes for bioimaging of osteoblasts.

Penicillium cyclopium lipase I (PCL) is a thermolabile triacylglycerol lipase with very low activity against monoacylglycerols, and there have been no reports on the transesterification of oil to produce biodiesel. A mutant PCLG47I with an improved thermostability was previously obtained through replacing Gly47 with Ile in PCL. In this study, a novel Pichia pastoris whole-cell biocatalyst (WCB) with overexpression of PCLG47I was constructed and characterized for biodiesel production from soybean oil. The optimum conditions for biodiesel preparation were 1 g soybean oil, 1 : 2 initial oil/methanol molar ratio with 3 times methanol addition of 1 : 0.75 oil/methanol molar ratio at 4 h intervals, 7% water content, 400 U lipase, temperature of 25 °C, and reaction time of 20 h. Under the optimum conditions, the FAME yield reached 60.7% and remained 47.3% after 4 batch cycles, and no glycerol was generated as a byproduct. These findings indicated that this WCB is a promising biocatalyst for biodiesel production in a relatively cost-effective manner. Additionally, the resulting enzymatic process may provide a potential method for biodiesel production at an industrial scale.

Lipases have been used in a wide range of applications, and thermostable lipases are highly required. Lipase I (PCL) from Penicillium cyclopium with alkali stability showed poor thermostability, resulting in a limited application in industrial processes with high temperatures. In this study, to expand the functionality of PCL, the thermostability of PCL was enhanced through direct evolution with error-prone PCR. Using a high-throughput activity assay, the double mutant PCL (L41P/G47I) with improved thermostability was selected, and then the single mutants L41P and G47I were constructed via site-directed mutagenesis. The mutant PCLs exhibited an optimum temperature 5 °C higher than the wild-type (WT). WT showed no activity with incubation at 40 °C for 90 min, whereas L41P, G47I, and L41P/G47I displayed 11%, 44%, and 23% of their maximal activity after incubation at 45 °C for 60 min. Meanwhile, the half-life at 45 °C of L41P, G47I, and L41P/G47I was 7-, 13-, and 9-fold higher, respectively, than that of WT. Moreover, G47I, L41P/G47, L41P, and WT were successfully applied in the synthesis of ethyl propionate with conversions of 45%, 27%, 23%, and 8%. The studies of circular dichroism spectroscopy and fluorescence spectroscopy indicated the lower flexibility and higher compactness of the structure of the mutant PCLs as compared with WT. Combining these results and analysis of the three-dimensional structure modeling, the mechanism responsible for the improvement of the thermostability was elucidated, which demonstrated that Leu41Pro and Gly47Ile could stabilize the structure of PCL through hydrophilic/hydrophobic interactions, proline substitution, and helix propensity.

Graphene has been proven to have great potential in medical applications. The goal of this study is to evaluate the toxicity of graphene on human microvascular endothelial cells (HMEC-1) under flowing conditions mimicking blood circulation. Graphene was prepared by the electrochemical exfoliation method and conjugated with poly(sodium-4-styrenesulfonate) (PSS) to improve its hydrophilicity and dispersion behavior. Under static cell growth conditions, 80 mg ml−1 of graphene reduced cell viability to 60% of the control. Graphene was observed to aggregate on the cell surface by interacting with filopodia. In contrast, graphene applied to cells under flowing conditions showed no significant negative influence on the cells regardless of graphene concentration, incubation time, and the exerted shear force. Graphene also showed lower toxicity towards cells in a flowing culture than multi-walled carbon nanotubes (MWCNTs) and carbon black. Together, these results suggest that the prolonged interaction of graphene with the cell surface is critical in causing cell damage. The lower circulatory toxicity of graphene compared to MWCNTs and carbon black also suggests that graphene is more suitable for use in drug delivery systems.

Metallic nanoparticles showed potent efficacy for diagnosis and therapy of cancer, but their clinical applications are limited by their poor tumor-targeting ability. Herein, peptide-functionalized 9 nm NaGdF

A novel set of nanoporous organic polytriazines with cyanate ester linkages, termed the NOP-14 series, have been designed and constructed from a new triangular monomer 2,4,6-tris(4-cyanatophenyl)-1,3,5-triazine. Four different concentrations of reactive groups in the same solvent medium, have been employed to allow an easy modulation of pore size. The cyanate ester-bridged networks demonstrates somewhat acceptable biocompatibility as identified by cell viability assays with HeLa cells using an MTT assay, and were used as new matrices for in vitro drug delivery of a model drug ibuprofen (IBU). This kind of nanoscale solid with limited surface areas ranging from 25 to 144 m2 g−1, however, can adsorb around 54 wt% of IBU (IBU/NOP-14 mass ratio 2 : 1, immersion time 24 h), demonstrating that the amount of inserted drug does not depend on the surface areas, but correlates more closely with the pore structure. The release behavior of IBU, depending on the porosities and structure of NOP-14 for host–drug interactions, is even better than that of its analogous PAF-6 as well as MCM-41. This study offers the possibility to facilely engineer pore structures through optimization of reaction conditions to control in vivo fate and also extends the controlled release of drugs to general polymers.

Improved thermal transport efficiency of carbon-based composites has been achieved by inserting metallic spacers within the temperature range of 50–150 °C. Al2O3, Ni, and SnO nano-particles are used as nanospacers in the graphite-like thin films, forming well-developed carbon framework. The composites show 42.5–57.7% increase in thermal conductivity (k), as compared with the pristine carbon. Among all the samples Al-inserted carbon composites exhibited the highest k value of 1128 W m−1 K−1 at 50 °C. The metallic nanopowders serve not only as filler but also as connective points for creating additional path for the heat conduction, leading to highly-efficient thermal diffusion. The apparent k value is found to be an increasing function of electrical conductivity, revealing that the conduction of free electrons is analogous to the thermal transport. The present work provided useful information concerning the thermal conduction and heat dissipation efficiencies of carbon-based composites, benefiting the design of thermal devices, e.g., heat sink and heat exchanger.

A series of polyimides (PIs) containing different weight ratios of polar piperazinyl and cholesterol side chains, denoted as PCPI, was synthesized in this study. These PIs were used as gate dielectrics of n-type organic field-effect transistors (OFETs) and as electrets of photo-assisted organic memories. The thermal properties of the PI/PCPI composite films were improved by increasing the spatial distribution of the PCPI molecules to form a thermally stable dielectric film. The performances of OFETs with PIs used as gate dielectrics, were gradually enhanced by increasing the mixture ratios of the PCPI molecules. A dipole field, which originated from the PCPI molecules into the OFETs, was introduced to observe the special phenomenon of output current growth over a long operation time. The application of these superior transistors with PCPI- and PI-mixed electrets to the field of organic memory resulted in a photo-assisted memory window of more than 38 V. The mechanisms of the carriers trapped in and released from the PI electrets were elucidated. Results showed that our devices possess excellent stability for OFETs and an extra-large memory window for organic memory devices.

The creation of stable and efficient photocatalysts that produce hydrogen from water under solar light is a burgeoning area of research. As a prospective candidate, TiO2 has been widely studied. Herein, we further designed and synthesized composites of mixed crystal TiO2 with high-performance carbon quantum dots (CQDs) via a facile approach. The CQDs were made by electrolyzing graphite rods and the mixed crystal TiO2 from titanium oxysulfate under a hydrothermal reaction, and then the resulting materials were heated to a high temperature under H2. All the characterization proved that the CQDs had been successfully modified onto TiO2 with both anatase and brookite phases. The newly synthesized samples showed an excellent performance for hydrogen evolution using AM 1.5 light sources. The large hydrogen evolution yield was 280 μmol h−1, which was higher than that produced by pure TiO2. It indicates that CQDs as electron storage could improve the separation of charges and inhibit the recombination of electron–hole pairs. Concurrently, the formation of heterostructures between the two phases of TiO2 would help electron–hole separation, which is another reason for the good performance of the photocatalyst.

Different TiO2 micro/nanostructures have been hydrothermally prepared through controlling the hydrolysis and nucleation rate of Ti4+ ions by urea and H2O2 in a (NH4)2TiF6 aqueous solution. Anatase TiO2 nanorods with diameters of 10–30 nm and lengths up to 300–500 nm were evolved from the intermediate monoclinic H2Ti5O11·3H2O in the presence of H2O2 and urea, whereas TiO2 core–shell nanospheres with diameters of 300–500 nm were obtained with the sole assistance of urea via the Ostwald ripening effect and TiO2 microspheres with diameters of about 1–2 μm were formed in the presence of only H2O2. Photocatalytic degradation of Rhodamine B (RhB) has been used to evaluate their activities. The results indicate that the anatase TiO2 nanorods have superior photocatalytic efficiency to the core–shell nanospheres and microspheres counterparts owing to their larger specific surface area and higher yield of ˙OH radicals. This work not only offers a simple and promising route to the controllable synthesis of various TiO2 architectures, but also provides new insight for improving the photocatalytic performance of TiO2 through morphological engineering, which will have potential applications in environmental remediation.

In this study, Co3O4 with different morphologies (leaf, sheet, and cube) are successfully synthesized by a facile hydrothermal method followed by calcination treatment. Representative samples with different morphological structures are compared and evaluated as anode materials in lithium-ion batteries. Relative to the Co3O4-sheet and Co3O4-cube samples, the Co3O4-leaf samples exhibit excellent electrochemical performance with high storage capacity (1245 mA h g−1 after 40 cycles at 0.1 C) and superior rate capability (0.1, 0.2, 0.5, 1, and 2 C for 1028, 1085, 1095, 1038, and 820 mA h g−1, respectively); interestingly, the thinner the samples are, the better their performance. Moreover, assisted by characterization by cyclic voltammetry and electrochemical impedance spectroscopy, we draw a conclusion that the ultra-thin structures result in shorter path lengths for the transport of lithium ions and electrons, benefiting conductivity and fast charge–discharge rates. More importantly, for Co3O4, the respective structure's degree of thickness has a great effect on the electrochemical performance in lithium-ion batteries. This new concept might be extended to prepare other anode and cathode materials for advanced energy storage and conversion devices.

A new kind of metal oxide nanoparticle coated with a uniform layer of N-doped carbon (e.g., Fe3O4@CNy, CoOx@CNy) was prepared readily in one-step. The nanoparticles show a high and stable lithium storage ability for lithium-ion battery applications.