Enhanced optical trapping of ZrO2@TiO2 photonic force probe with broadened solvent compatibility

Optical trapping and manipulating nanoparticles are essential tools for interrogating biomedicine at the limits of space and time. Typically, silica or polystyrene microspheres are used as photonic force probes. However, adapting those probes to organic solvents is an ongoing challenge due to the limited solvent compatibility and low refractive index mismatch. Here we report on the optical force enhancement and solvent compatibility that utilizes ZrO₂@TiO₂ core-shell nanoparticles. We experimentally demonstrate that the 450-nm-diameter ZrO₂@TiO₂ core-shell nanoparticles achieve the lateral and axial trap stiffness up to 0.45 pN µm^-1 mW^-1 and 0.43 pN µm^-1 mW^-1 in water, showing more than fivefold and ninefold improvement on the ordinary SiO₂ particle of the same size. In addition, ZrO₂@TiO₂ core-shell nanoparticles can realize stable three-dimensional trapping in both polyethylene glycol and glucose solutions. This optical trapping enhancement property, coupled with solvent compatibility, expands the range of feasible optical trapping experiments and will pave the way toward more advanced biological applications.

Facile Ionization of the Nanochannels of Lamellar Membranes for Stable Ionic Liquid Immobilization and Efficient CO2 Separation

Two-dimensional (2D) lamellar membranes, with highly ordered nanochannels between the adjacent layers, have revealed potential application prospects in various fields. To separate gases with similar kinetic diameters, intercalation of a functional liquid, especially an ionic liquid (IL), into 2D lamellar membranes is proved to be an efficient method due to the capacity of imparting solubility-based separation and sealing undesired defects. Stable immobilization of a high content of liquid is challenging but extremely required to achieve and maintain high separation performance. Herein, we describe the intercalation of a typical IL, 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM][BF₄]), into the ionized nanochannels of sulfonated MXene lamellar membranes, where the sulfonate groups are anchored onto MXene nanosheets through a facile method based on metal-catechol chelating chemistry. Thanks to the intrinsic benefits of MXene as building blocks and the decorated sulfonate groups, the optimal membrane possesses adequate interlayer spacing (∼1.8 nm) and high IL uptake (∼47 wt %) and therefore presents a CO₂ permeance of 519 GPU and a CO₂/N₂ selectivity of 210, outperforming the previously reported liquid-immobilized lamellar membranes. Moreover, the IL loss rate of the membrane within 7 days at elevated pressure (5 bar) is measured to be significantly decreased (from 43.2 to 9.0 wt %) after growing sulfonate groups on the nanochannel walls, demonstrating the excellent IL storage stability.

Flavin-Conjugated Iron Oxide Nanoparticles as Enzyme-Inspired Photocatalysts for Azo Dye Degradation

In this work, a new photocatalytic system consisting of iron oxide nanoparticles (IONPs), coated with a catechol-flavin conjugate (DAFL), is synthesized and explored for use in water remediation. In order to test the efficiency of the catalyst, the photodegradation of amaranth (AMT), an azo dye water pollutant, was performed under aerobic and anaerobic conditions, using either ethylenediaminetetraacetic acid (EDTA) or 2-(N-morpholino)ethanesulfonic acid (MES) as electron donors. Depending on the conditions, either dye photoreduction or photooxidation were observed, indicating that flavin-coated iron-oxide nanoparticles can be used as a versatile enzyme-inspired photocatalysts.

Synergy of Catechol-Functionalized Zinc Oxide Nanorods and Porphyrins in Layer-by-Layer Assemblies

Catechol-functionalized, positively charged ZnO nanorods (NRs) and anionic porphyrins were integrated into layer-by-layer (LbL) assemblies. In general, this study focuses on the impact that different porphyrins, varying in size and number of negative charges, exert on the LbL architecture in terms of morphology and spectroscopy. In particular, through a combination of analytical methods, including UV/Vis spectroscopy, SEM, and profilometry, valuable insights into LbL assembly formation were gathered. A key feature was the surface coverage in the resulting films. Denser films and surface coverages were realized when highly negatively charged and sterically demanding porphyrins were employed. As a complement to basic characterization, the LbL assembled films were used to fabricate proof-of-concept solar cells.

Durable defense: robust and varied attachment of non-leaching poly"-onium" bactericidal coatings to reactive and inert surfaces

Developing antimicrobial coatings to eliminate biotic contamination is a critical need for all surfaces, including medical, industrial, and domestic materials. The wide variety of materials used in these fields, from natural polymers to metals, require coatings that not only are antimicrobial, but also contain different surface chemistries for covalent immobilization. Alkyl "-onium" salts are potent biocides that have defied bacterial resistance mechanisms when confined to an interface. In this feature article, we highlight the various methods used to covalently immobilize bactericidal polymers to different surfaces and further examine the mechanistic aspects of biocidal action with these surface bound poly"-onium" salts.

Band edge engineering of TiO2@DNA nanohybrids and implications for capacitive energy storage devices

Novel mesoporous TiO2@DNA nanohybrid electrodes, combining covalently encoded DNA with mesoporous TiO2 microbeads using dopamine as a linker, were prepared and characterised for application in supercapacitors. Detailed information about donor density, charge transfer resistance and chemical capacitance, which have an important role in the performance of an electrochemical device, were studied by electrochemical methods. The results indicated the improvement of electrochemical performance of the TiO2 nanohybrid electrode by DNA surface functionalisation. A supercapacitor was constructed from TiO2@DNA nanohybrids with PBS as the electrolyte. From the supercapacitor experiment, it was found that the addition of DNA played an important role in improving the specific capacitance (Cs) of the TiO2 supercapacitor. The highest Cs value of 8 F g(-1) was observed for TiO2@DNA nanohybrids. The nanohybrid electrodes were shown to be stable over long-term cycling, retaining 95% of their initial specific capacitance after 1500 cycles.