Mussel-inspired polydopamine-encapsulated carbon dots with dual emission for detection of 4-nitrophenol and Fe3.

Carbon dots (CDs) with excellent optical properties are widely used in biomedicine, fluorescence sensing, and light-emitting diodes (LEDs). However, it is still a challenge to prepare CDs that can stably emit red fluorescence in the water environment. In this study, polydopamine-encapsulated luminescent carbon dots (CDs@PDA) with an encapsulating structure were synthesized at room temperature from p-phenylenediamine-derived red-light CDs as the core and using mussel-inspired chemical properties of polydopamine (PDA). In the binary system of water:ethanol = 1: 3 (volume ratio), the as-prepared CDs@PDA had a dual emission of ultraviolet light (330 nm) and red light (640 nm) with the fluorescence quantum yields of 8.0 and 15.5%, respectively, at the same time under 285 nm light excitation. The as-prepared CDs@PDA could be directly used for fluorescence selective sensing of 4-nitrophenol (4-NP) and Fe3+ through simultaneously quenching of ultraviolet and red fluorescence based on the internal filtration effect mechanism with detection limits of 3.44 and 3.75 µM, respectively. This research showed that PDA-coated CDs can significantly improve the photoluminescence stability of CDs with new optical features. This means that the encapsulated structure of mussel chemistry is very helpful for expanding the application range of CDs in the water environment.

A facile strategy to fabricate thermoresponsive polymer functionalized CdTe/ZnS quantum dots: assemblies and optical properties.

Novel thermoresponsive CdTe/ZnS quantum dots (QDs) decorated with a copolymer ligand (CPL) containing 8-hydroxyquinoline and NIPAM units are prepared through coordinate bonding in aqueous solution. The dependence of the morphology and optical properties of the QDs/CPL assemblies formed via coordinate bonding on the experimental conditions is studied. The coordinate induced self-assemblies are observed by controlling the molar ratio of QDs and CPL. The self-organized structure of QDs/CPL proceeds through a first step of QDs-chains, followed by a necklace-like single annular chain, and subsequently increases its annular chain structure, forming a network. The CPL functionalized QDs can emit multiple colors from the cooperating interaction between the inherent emission (606 nm) of the QDs and the surface-coordinated emission (517 nm) of the CPL complex formed on the QD surface. For QDs-CPL systems, both Förster resonance energy transfer (FRET) and a high rate of photoinduced electron transfer (PET) are simultaneous, the latter mainly contributing to PL quenching. The thermoresponsive QDs/CPL assemblies also exhibit dual reversible PL properties between the inherent emission of QDs and surface-coordinated emission.

Fabrication of biomimetic high performance antireflective and antifogging film by spin-coating.

In this paper, we report a facile way to fabricate biomimetic high performance optical hybrid films with excellent antireflective and antifogging properties by one-step spin-coating the mixture of mesoporous SiO(2) particles and SiO(2) sol. The production process of the films is easy, low-cost, and time-efficient. Mesoporous SiO(2) particles containing surfactants disperse in SiO(2) sol stably without any chemical modification, which decrease the effective refractive index and increase the transmittance of the films. In addition, such films possess superhydrophilic properties and exhibit high performance antifogging properties. Due to the good film forming performance of SiO(2) sol, mesoporous SiO(2) particles are embedded in the films and impart the films high mechanical stability and durability. The surface morphology of the films can maintain well after repeated friction, and the performances of antireflective and antifogging also do not change as well.

Biomimetic polyimide nanotube arrays with slippery or sticky superhydrophobicity.

In this paper, we report the fabrication of superhydrophobic polyimide (PI) nanotube arrays with different topographies, which possess slippery or "sticky" superhydrophobicity. The PI nanotube arrays were fabricated by the porous alumina membrane molding method. We regulated three kinds of solvent evaporation and drying processes, which controlled different congregated and noncongregated topographies of PI nanotube arrays. Large scale comb-like congregated topography possesses a small sliding angle (SA<5 degrees), small scale comb-like congregated topography possesses a medium sliding angle (SA is about 30 degrees), noncongregated topography possesses a large sliding angle (strong adhesive force to water droplet). Moreover, the as-prepared superhydrophobic PI nanotube arrays have remarkable resistivity to acid, weak base, high temperature (up to 350 degrees C) and various organic solvents. Our work provides a facile and promising strategy to fabricate superhydrophobic surfaces with controlled sliding angles by utilizing self-organization effect, and such high performance superhydrophobic PI nanotube arrays can be used as coating materials in various harsh conditions.