Dual-Responsive hollow mesoporous organosilicon nanocarriers for photodynamic therapy.

HYPOTHESIS: The nano-delivery platform, -SS-HMONs@MB@MnO2 nanoparticles (SMM NPs) loaded with methylene blue (MB) as photosensitizer have excellent photodynamic therapy (PDT) effect. The disulfide bond and MnO2 give the shell redox-responsive properties. SMM NPs consume glutathione (GSH) in tumor cells, reducing the scavenging of reactive oxygen species (ROS) by GSH and enhancing the PDT effect of MB. EXPERIMENTS: The GSH dual-responsive nano-delivery platform, was designed and constructed by using disulfide-doped hollow mesoporous organosilicon nanoparticles (-SS-HMONs) as intermediate responsive layer, loaded with MB as photosensitizer and coated with MnO2 as shells. The MB photosensitizer release and GSH response were characterized. The PDT effect of nanoparticles was evaluated. FINDINGS: The SMM NPs were uniform in size and well dispersed. The nanoparticles could react with GSH, leading to the decomposition of MnO2 shells and the breakage of disulfide bonds in -SS-HMONs, resulted in the release of MB photosensitizer. The cell experiment showed that SMM NPs had good ROS generating ability and PDT effect after being sucked by tumor cells, which could effectively kill tumor cells. However, in vivo experiments demonstrated that SMM NPs showed slight inhibition on tumor growth. The actual effect in animals was different from the effect in cells.

A pathway for promoting bioelectrochemical performance of microbial fuel cell by synthesizing graphite carbon nitride doped on single atom catalyst copper as cathode catalyst.

In this study, a simple distributed feeding method was used to dope graphite phase carbon nitride (g-C3N4) on single atom catalyst (SAC) copper (Cu) to form composite material (Cu-SA/CN). Cu-SA/CN was formed by mutual doping of polyhedral block Cu and irregular g-C3N4. There were obvious crystal face peaks at 28.4, 43.3, 47.3 and 56.2°. Large solid Cu and small irregular g-C3N4 were successfully combined and C, Cu, N and O elements were uniformly distributed on the surface of Cu-SA/CN. The valence bond of N-CN, C-NC, CC and OH was found. When the Cu content was 0.03 mol, Cu-SA/CN3 showed excellent redox activity. The maximum power density of Cu-SA/CN3-MFC was 456.976 mW/m2, the maximum voltage was 599 mV, which could be stable for 7 d. Cu-SA/CN3 was proved to provide more electrically active sites, strong catalytic oxygen reduction ability and conductivity.

A Selenium-Substituted Heptamethine Cyanine Photosensitizer for Near-Infrared Photodynamic Therapy.

Photodynamic therapy (PDT) is a relatively safe approach to cancer treatment without significant systemic side effects or drug resistance. However, the current PDT efficiency is unsatisfactory due to the lack of near-infrared (NIR) photosensitizers. Heptamethine cyanine (Cy7) dyes are well-known NIR fluorophores and are also used as photosensitizers. But their singlet oxygen quantum yields (ΦΔ ) are not ideal. Herein, we developed an NIR photosensitizer with a long-lived excited triplet state (τ=4.3 µs) by introducing a selenium atom into the structure of a Cy7 dye. The new NIR photosensitizer exhibits a significantly high singlet oxygen quantum yield (ΦΔ =0.11). Its good PDT effect was demonstrated in the living cells. Considering that the selenium-substituted photosensitizer has a very low dark cytotoxicity and good chemical stability, we conclude that it will have a promising future in biomedical and clinical applications.

Au@mSiO2 core-shell nanoparticles loaded with fluorescent dyes: synthesis and application for imaging performance.

Here, Au@mSiO2 core-shell nanoparticles were easily synthesized by a one-pot method. Positively charged alkyl chains with different lengths were modified on the surface of the particles. Thus composite nanoparticles with different potentials and hydrophilic interface properties were prepared. Based on the charge properties of the shell surface, the process of loading dyes was simplified by the strong electrostatic adsorption between the particle surface and the heterogeneous negatively charged dyes. The fluorescence intensity and fluorescence lifetime of the loaded fluorescent dyes showed that the dyes could not produce effective tunneling in the mesoporous materials, which was limited to the surface of the particles, which is beneficial for the subsequent research on the loading or release of nanoparticles. After loading, the nanoparticles still exhibit a high fluorescence intensity, enabling dual-mode microscopic imaging (TEM and fluorescence).

Enhancing Intersystem Crossing to Achieve Thermally Activated Delayed Fluorescence in a Water-Soluble Fluorescein Derivative with a Flexible Propenyl Group.

It is a challenge to rationally design an organic molecule with thermally activated delayed fluorescence (TADF) due to the intrinsically spin-forbidden transition. Meanwhile, those reported TADF organic molecules have difficulty to be directly applied in the field of biological and medical imaging because they usually have no water solubility. Here, a water-soluble TADF organic molecule DCF-BXJ was developed by introducing a flexible propenyl group into the commercial traditional fluorophore DCF (2,7-dichlorofluorescein). The flexible group provides nonradiative rotational motion, which causes an efficient energy level cross between the S1 state and the T2 state of DCF-BXJ. Results of transient absorption spectra and theoretical calculations supported that nonradiative rotational motion of the flexible group can enhance intersystem crossing (ISC) and bring out TADF. This work provides a new mechanism explanation for TADF existing in organic molecules.

Triboelectric effect-modulated varifocal liquid lens.

Electrically modulated varifocal liquid lenses, which are usually modulated by an external high voltage power source, have attracted much attention due to their bright application prospects in artificial optical systems. Here, a triboelectric nanogenerator (TENG)-based varifocal liquid lens (TVLL) has been demonstrated, in which the focal length can be directly modulated by external mechanical sliding. A dielectrophoretic force is generated by the TENG through the transfer of triboelectric charges in the asymmetric electrodes, which is used to continuously change the shape of the air-liquid interface between concave and convex without any complicated boost converter. Moreover, a triboelectric magnifying glass based on the accurate modulation effect of the TVLL on a light beam has been demonstrated. In this work, the TENG is used as a medium to modulate and accurately control the focal length of the liquid lens by an external mechanical stimulus, which may have great applications in micro-optical-electro-mechanical systems (MOEMS), human-machine interaction, artificial vision systems, etc.

Perspective to the Potential Use of Graphene in Li-Ion Battery and Supercapacitor.

Graphene is a hot star in materials science with various potential application aspects, including in Li-ion battery and supercapacitor. The burst of scientific papers in this area seems to validate the performance of graphene, but also arouses large dispute. Herein, we share our judgment of these trends to all, encouraging the discussion and enhancing the understanding of the structure-performance relationship of graphene.