A DNA origami-based platform for detecting aflatoxin B1 has been constructed with the assistance of aptamer probes and its complementary ssDNA-modified gold nanoparticles. This work may open new horizons for the application of DNA origami in the detection of a variety of small molecules.

Silver nanoparticles (AgNPs) have been extensively studied as antimicrobial materials, but their capability of suppressing aflatoxin production has not been investigated. In this work, AgNPs with an average size of 4.5 nm were synthesized to inhibit the growth of Aspergillus flavus (A. flavus). Based on the anti-fungal assay, the concentration of 5 μg mL−1 was chosen to study the direct inhibiting effects of AgNPs on aflatoxin production. Results show that AgNP treatment could significantly decrease secretion of aflatoxin B1 from A. flavus. Real-time measurements of O2− with an electrochemical sensor reveal that the AgNPs could trigger the release of O2− from fungal mycelia. A mechanism involving O2− release is proposed to explain AgNP-caused depression of aflatoxin production from A. flavus. This is the first attempt to study AgNP-induced inhibition on aflatoxin generation and its possible mechanisms.

In the present study, a ferric ion (Fe3+)-assisted in situ synthesis approach was developed to grow silver (Ag) nanoplates on the polydopamine (PDA)-coated silk without the use of additional reductants. The essential role of Fe3+ in the formation of Ag nanoplates is revealed by comparing the morphologies of Ag nanostructures prepared on the silk-coated PDA film with/without Fe3+ doping. Scanning electron micrographs show that high-density Ag nanoplates could be synthesized in the reaction system containing 50 μg/mL FeCl3 and 50 mM AgNO3. The size of the Ag nanoplate could be tuned by adjusting the reaction duration. Based on the data, a mechanism involving the Fe3+-selected growth of Ag atoms along the certain crystal faces was proposed to explain the fabrication process. Transmission electron microscopy and X-ray diffractometry indicate that the Ag nanoplates possess good crystalline structures. Raman spectra demonstrate that the nanoplates could strongly enhance the Raman scattering of the PDA molecules. The Ag nanoplate-coated silk could be utilized as a flexible substrate for the development of surface-enhanced Raman scattering biosensors.

Layer-by-layer (LbL) assembly is a versatile technique for the preparation of multilayered polymeric films. However, fabrication of LbL polymetic film on silk for the in situ growth of high-density silver nanoparticles (AgNPs) has not been realized. Herein poly(acrylic acid) (PAA)/poly(dimethyldiallylammonium chloride) (PDDA) multilayers are constructed on silk via the LbL approach, subsequently serving as a 3-dimensional matrix for in situ synthesis of AgNPs. After 8 rounds of LbL assembly, the silk is fully covered with a layer of polymeric film. AgNPs with good crystalline structures could be in-situ generated in the silk-coated multilayers and their amount could be tailored by adjusting the bilayer numbers. The as-prepared silk could effectively kill the existing bacteria and inhibit the bacterial growth, demonstrating the antimicrobial activity. Moreover, the release of Ag+ from the modified silk can last for 120 h, rendering the modified silk sustainable antimicrobial activity. This work may provide a novel method to prepare AgNPs-functionalized antimicrobial silk for potential applications in textile industry.

Effects of oligonucleotide length and probe number on the assembly of gold nanoparticles (AuNPs) with DNA origami templates were investigated for the first time. The optimal length and probe number are proposed to efficiently anchor AuNPs for the construction of plasmonic chiral nanostructures.

Development of biomass-derived carbon/MnO2 composites for energy applications has recently been attracting tremendous attention. However, the combination of MnO2 nanosheets and conidia-derived hollow carbon spheres for supercapacitor applications has never been realized. In this work, we develop a facile method to grow MnO2 nanosheets on hollow carbon spheres derived from Aspergillus flavus conidia. Ultrathin MnO2 nanosheets are uniformly grown on the surface of conidium-derived hollow carbon spheres. Sulfur element from the conidia is doped in the composites and the amount of MnO2 in the material is ∼50.2 wt%. The as-prepared MnO2–carbon sphere composited electrode possesses a high specific capacitance of 263.5 F g−1 at 1 A g−1. After 2000 cycles, the specific capacitance value remains 83% of retention and the coulombic efficiency remains as high as 94%, demonstrating the excellent cycling stability.

Carbon nanotubes (CNTs) have been employed as supporting materials for the dispersion of gold nanoparticles (AuNPs) to achieve improved catalytic properties. However, the application of CNT–AuNP composites for the evaluation of chlorophenols (CPs) is not reported. Herein, gold nanoparticle/carboxyl functionalized multi-walled carbon nanotube (AuNPs@cMWCNT) nanocomposites were synthesized via an in situ reduction method and further characterized with field emission scanning electron microscopy (FESEM), ultraviolet-visible (UV-vis) spectroscopy and X-ray diffraction (XRD). The AuNPs@cMWCNT modified glassy carbon electrode was subsequently prepared as a sensor for the electrochemical detection of 4-chlorophenol (4-CP). The electro-oxidation of 4-CP on the sensor is an adsorption-controlled irreversible process, which undergoes a two-electron and two-proton transfer. Under the optimal conditions, the oxidation peak current was proportional to the 4-CP concentration in the range of 0.3 to 400 μM, with a detection limit of 0.11 μM. The experimental data demonstrate that the sensor has great reproducibility, long-term stability, high specificity and excellent feasibility. The AuNPs@cMWCNT based sensor could be a facile, low-cost and rapid tool for the potential on-line monitoring of 4-CP in practical applications.

Textile-based supercapacitors have recently attracted much attention owing to their great potential as energy storage components in wearable electronics. However, fabrication of a high-performance, fully printed, and ultraflexible supercapacitor based on a single textile still remains a great challenge. Herein, a facile, low-cost, and textile-compatible method involving screen printing and transfer printing is developed to construct all-solid-state supercapacitors on a single silk fabric. The system exhibits a high specific capacitance of 19.23 mF cm–2 at a current density of 1 mA cm–2 and excellent cycling stability with capacitance retention of 84% after 2000 charging/discharging cycles. In addition, the device possesses superior mechanical stability with stable performance and structures after 100 times of bending and twisting. A butterfly-patterned supercapacitor was manufactured to demonstrate the compatibility of the printing approaches to textile aesthetics. This work may provide a facile and versatile approach for fabricating rationally designed ultraflexible textile-based power-storage elements for potential applications in smart textiles and stretchable/flexible electronics.Keywords: flexibility; screen-printing technique; silk fabric; supercapacitor; wearable electronics;

A repeated coating-reduction approach was developed to directly immobilize graphene nanosheets on silk for high conductivity. The as-prepared highly conductive graphene-coated silk fabrics (1.5 kΩ sq−1) and fibers (3595 S m−1) are promising as the functional supporting matrix and conducting fabrics/wires in future wearable electronics.

Transient spikes from the bacteriorhodopsin (bR) photocycle are triggered with NIR irradiation for the first time by integrating bR with upconversion nanoparticles. This work may open new horizons for the bR applications in the IR wavelength range.

A polydopamine–Fe3O4 nanocomposite-based H2O2 electrochemical sensor is fabricated to real-time monitor the transmembrane release of reactive oxygen species from citral-treated Aspergillus flavus, revealing a mechanism involving transient transmembrane secretion of H2O2 for the citral-caused inhibition of aflatoxin production from a fungus for the first time.

A composite of selenium (Se) and a rich porous carbon material (PCM) with mesopores from silk cocoons is explored as a cathode for lithium–selenium (Li–Se) batteries for the first time. Elemental selenium is homogeneously dispersed inside the mesopores of the PCM by a melt-diffusion method based on several analyses. The synthetic PCM/Se composite can effectively suppress the dissolution of the active material and maintain mechanical stability. In the case of Li–Se batteries, it delivers a reversible capacity of more than 230 mA h g−1 after 510 cycles at 2C. The remarkable electrochemical performance may benefit from the favorable conductivity and the porous structure of the carbon material as the host matrix.

One dimensional TiO2 nanomaterials have attracted tremendous attention due to their excellent photocatalytic properties. However, the synthesis of spherical-shaped carbon nanotubes (CNTs)–TiO2 nanorod composites for photocatalytic degradation of water pollutants has not been reported. In the present study we fabricated fluffy-ball-shaped multiwalled CNT–TiO2 nanorod composites via a facile hydrothermal approach. By using scanning electron microscopy (SEM) and transmission electron microscopy (TEM), it is found that morphologies of the nanocomposites could be controlled by changing the reaction duration, CNT amount and Ti source concentration. TEM images and X-ray powder diffraction (XRD) results show the excellent crystalline structure and the rutile phase of the TiO2 nanorods in the nanocomposites. Based on the results, a possible mechanism for the growth of the nanocomposites was proposed. Great potentials of the composited microspheres in water treatment were demonstrated through the photocatalytic degradation of methylene blue, in which a degradation efficiency as high as 93% could be reached. This study provides not only a new approach to developing CNT–TiO2 nanorod composites, but also a very promising photocatalyst for potential applications in waste water treatment.

A conidium-templated approach is developed to prepare carbon hollow microspheres, which demonstrate great potential to be applied as anode materials in lithium-ion batteries. This work may provide a novel method to fabricate conidium-derived carbon materials for energy systems.

Aflatoxin B1 (AFB1), a secondary fungal metabolite of Aspergillus flavus, was employed as a model mycotoxin to establish an aptamer based assay that exploits the quenching of the fluorescence of CdTe quantum dots (Q-dots) by graphene oxide (GO). A thiolated aptamer specific for AFB1 was linked to the surface of Q-dots via ligand exchange. The fluorescence of the aptamer modified-Q-dots is strongly quenched by GO. If, however, AFB1 is added, fluorescence is restored depending on the quantity of AFB1 added. The system was evaluated both in phosphate buffer solution and in peanut oil. If performed in an aqueous system, the assay possesses good selectivity, a wide dynamic range (from 3.2 nM to 320 μM) and a low limit of detection (1.0 nM). If performed in peanut oil solution, the dynamic range is from 1.6 nM to 160 μM, and the limit of detection is 1.4 nM. In our perception, this is a simple, sensitive and selective method for the determination of AFB1 that also may be extended to the analysis of other mycotoxins.

The BRAFV600E inhibitor PLX4032 (Vemurafenib) is an FDA-approved new drug for the treatment of metastatic melanomas, which specifically inhibits the RAS/MEK/ERK signaling pathway to control cell proliferation and adhesion. However, no study has been carried out to investigate the role of intracellular oxidative balance in PLX4032-induced tumor growth inhibition. Herein, for the first time, superoxide (O2˙−) and nitric oxide (NO) generated from PLX4032-challenged melanoma cells were monitored using electrochemical sensors and conventional fluorescein staining techniques. Impacts of superoxide dismutase (SOD) and NG-monomethyl-L-arginine monoacetate (L-NMMA), a nitric oxide synthase inhibitor, were also examined to demonstrate the specificity of ROS/NO generation and its biological consequences. PLX4032 specifically triggers production of O2˙− and NO from BRAFV600E mutant A375 cells. SOD and L-NMMA could abolish the PLX4032-induced increase in intracellular O2˙− and NO production, thereby rescuing cell growth in BRAF mutant A375 cells (A375BRAFV600E). In addition, PLX4032 treatment could decrease the mitochondrial membrane potential in A375BRAFV600E cells. The results suggest that PLX4032 can selectively cause ROS production and depolarization of mitochondrial membranes, potentially initiating apoptosis and growth inhibition of PLX4032-sensitive cells. This work not only proposes a new mechanism for PLX4032-induced melanoma cell inhibition, but also highlights potential applications of electrochemical biosensors in cell biology and drug screening.

•Silk was coated with silver nanoparticles via a UV-assisted in situ synthesis approach.•The density of silver nanoparticles depends on the UV-irradiation time.•The immobilized silver nanoparticles possess good crystalline structures.•The antibacterial activity of the silver nanoparticles-coated silk was demonstrated.To overcome the bacteria-caused degradation of silk, an ultraviolet light (UV)-assisted in situ synthesis approach is developed to immobilize silver nanoparticles (AgNPs) on degummed silk fibers for antibacterial applications. Results show that AgNPs with excellent crystalline structures are efficiently attached on the silk surface in an irradiation time-dependent manner. The immobilization of AgNPs could greatly delay the thermal degradation of silk. The antibacterial activity of the AgNPs-coated silk is evaluated by the growth curve of bacteria, zone of inhibition and dual staining assays, clearly demonstrating its bacterial growth inhibition ability and bactericidal effects. This work offers potentials to produce specific AgNPs-coated antimicrobial silk for various applications in textile industry.

Nanosilver is regarded as a new generation of antibacterial agents and has great potential to be utilized in antibacterial surface coatings for medical devices, food package and industrial pipes. However, disadvantages such as easy aggregation, uncontrollable release of silver ions and potential cytotoxicity greatly hinder its uses. Recently, polymers possessing unique functions have been employed to fabricate nanocomposite coatings with nanosilver for better biocompatibility and enhanced antibacterial activity. This review starts with progress on antibacterial mechanism and cytotoxic effects of nanosilver. Antibacterial functions of polymers are subsequently discussed. Advances of fabrication of polymer/nanosilver composite coatings for antibacterial applications are surveyed. Finally, conclusions and perspectives, in particular future directions of polymer/nanosilver composite coatings for antibacterial applications are proposed. It is expected that this review is able to provide the updated accomplishments of the polymer/nanosilver composite coatings for antibacterial applications while attracting great interest of research and development in this area.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Progress on antibacterial mechanism and cytotoxic effects of nanosilver is presented. ► Antibacterial functions of polymers are described. ► Recent proceedings in fabrication of polymer/nanosilver composite coatings for antibacterial applications are surveyed. ► Future challenges and directions of polymer/nanosilver composite coatings for antibacterial applications are proposed.

•A layer-by-layer film incorporating quantum dots and poly-l-lysine was fabricated.•The film shows tunable optical properties and antibacterial activity.•The film is built up in a logarithmic growth mode.Tunable absorption/emission and antibacterial activity are highly desirable for antibacterial decorative coating layers. In this study, films with both tunable optical and effective antibacterial properties were fabricated with cadmium telluride quantum dots (QDs) and poly-l-lysine (PLL) via layer-by-layer assembly. Absorption and photoluminescence spectra as well as surface morphology were examined to monitor the film growth. The films are fabricated in a logarithmic growth mode, exhibiting effective antibacterial activity against Escherichia coli and good biocompatibility to Hela cells. By changing sizes of the incorporated QDs, optical properties of the films can be easily tailored. The PLL/QDs' multilayered films may be used as colorful coating layers for applications requiring both unique optical and antibacterial properties.

Transient spikes from the bacteriorhodopsin (bR) photocycle are triggered with NIR irradiation for the first time by integrating bR with upconversion nanoparticles. This work may open new horizons for the bR applications in the IR wavelength range.

A repeated coating-reduction approach was developed to directly immobilize graphene nanosheets on silk for high conductivity. The as-prepared highly conductive graphene-coated silk fabrics (1.5 kΩ sq−1) and fibers (3595 S m−1) are promising as the functional supporting matrix and conducting fabrics/wires in future wearable electronics.

A DNA origami-based platform for detecting aflatoxin B1 has been constructed with the assistance of aptamer probes and its complementary ssDNA-modified gold nanoparticles. This work may open new horizons for the application of DNA origami in the detection of a variety of small molecules.