Nano

Magnetic field-assisted drug delivery is a fascinating strategy to transport chemotherapeutic drugs. Ferrite nanoparticles (NPs) of the form MFe₂O₄ are a good choice for utilization as magnetic nanocarriers. Although many ferrite NPs have been tested for their function as nanocarriers, their nonspecific toxicity must be minimized. In this work, calcium–nickel ferrite nanoparticles (CNF MNPs) coated with dextran–$\beta$-cyclodextrin and dextran–$\beta$-cyclodextrin–dextran polymers are reported. The synthesized NPs are characterized using XRD, TEM, EDX and XPS. The magnetic properties are investigated by vibrating sample magnetometry. The 20 nm-sized CNF MNPs fall in the size range suitable for cancer drug transport. The magnetic nanocarriers containing the polymers are superparamagnetic. The camptothecin (CPT) loading efficiency is observed as 88%. The in vitro CPT release profiles are sustained, displaying a continuous release for a period of above 45 h. The cytotoxicity studies on A549 cell lines reveal that the CPT-loaded CNF MNPs are active against them and can be used as an anticancer drug carrier.

Graphite carbon nitride (g-C₃N${}_4)$ polymer with two-dimensional planar structure is a new star in nanodrug delivery systems in recent years because it shows characteristics of low cost, nontoxicity, biocompatibility and easy functionalization. However, conventional g-C₃N₄ shows bulk, macro size, small specific surface area and poor water solubility. To improve this, most works are always confined to physical ultrasound, oxidative peeling or template-strategy, which have the disadvantages of redundant steps, environment-unfriendliness and high cost. In this paper, a modified supramolecular self-assembled strategy was carried out to construct a novel graphitic carbon nitride nanoplatform (named by CA-MA${}_X)$ using melamine and cyanuric as precursors. The chemical structure characterization, drug loading experiment and cell tests in vitro of the CA-MA${}_X$ nanoplatform were carried out and discussed in detail. Results indicated that the obtained samples show enhanced specific surface area, more exposed groups and good biocompatibility. Compared to the traditional carbon nitride (named by MA-CN), the newly prepared CA-MA${}_X$ carrier shows improved drug loading efficiency and good pH-responsive loading, as well as releasing. Cell uptake experiment demonstrates that CA-MA₂-DOX can be swallowed by cancer cells and during treatment of the cancer cell process, the CA-MA₂-DOX complex experiences phagocytizing by the cancer cell, controlled-release DOX and kills the cancer cell after DOX was passively diffused into the nucleus. CA-MA₂-DOX exhibited significant in vitro antitumor activity. To our knowledge, this is the first time the supramolecular self-assembled method was used in carbon nitride nanocarrier construction for cancer treatment.

Rechargeable nonaqueous Li-O₂ batteries are considered as one of the most promising energy storage systems due to their super-high theoretical energy density. However, some technical obstacles, such as high overpotential and poor cycle stability, need to be overcome urgently, so that it is possible to make Li-O₂ batteries commercially viable. The key is to develop effective bifunctional cathode catalysts. Herein, Ni-doped TiO₂ (Ni-TiO${}_2)$ with microtubule structure was prepared by hydrothermal method and used as the cathode catalyst of Li-O₂ batteries. At a current density of 100mAg${}^{-1}$, Li-O₂ batteries with Ni-TiO₂ catalysts showed an initial discharge capacity of 5100mAh g${}^{-1}$ and can maintain 52 stable cycles at 100mAg${}^{-1}$ with a fixed capacity of 500mAhg${}^{-1}$. The microtubule structure composed of nanosheets not only facilitates the diffusion of O₂ and electrolyte, but also provides abundant catalytic sites for oxygen reduction reactions and oxygen evolution reactions (ORR/OER). In addition, the Ni doping into the structure of TiO₂ can significantly enhance the catalytic activity of ORR/OER, resulting in a reduced discharge/charge overpotential and enhanced discharge-specific capacity.

To improve the activation efficiency of PMS to efficiently degrade antibiotic sulfadiazine (SD), herein, a Co@MoS₂ catalyst was prepared by a one-step hydrothermal process. The unique petal-like structure of MoS₂ enables the transition metal Co to achieve high dispersion and avoid agglomeration. Mo(IV) and unsaturated S accelerate the electron transfer between Co${}^{2+}$ and Co${}^{3+}$ to improve the cycling efficiency and thus realize the efficient activation of PMS. The results of active substance quenching experiment and ESR analysis show that the main active substance for the efficient degradation of SD by Co@MoS₂ is the non-radical ¹O₂, while the other three radicals $\cdot {\mathrm{\text{O}}}_2^{-}$, ⋅OH and ${\mathrm{\text{SO}}}_4^{•-}$ contribute significantly to the efficient degradation of SD. And after 5 cycles, the degradation could still be as high as 90%. The strong consolidation of Co on the petal-shaped sheet of MoS₂ ensures the stability of Co@MoS₂ catalyst.

Development of a low-cost hand-held nitric oxide (NO) sensor with high selectivity, sensitivity and low detection limit is attractive for environment and health monitoring applications. NO gas sensor was fabricated using hydrothermally grown ZnO nanorods (ZnO NRs). The sensing performance like sensor response, sensitivity, detection limit has been improved significantly by attaching gold nanoparticles (Au NPs) with ZnO NRs. Au NPs were synthesized by chemical reduction method from gold chloride trihydrate. The attachment of Au NPs on nanorods was done by spin coating method. The maximum sensor response and sensitivity were obtained at $\sim 100^{\circ }$C operating temperature with $300\mu$l gold loading. The interference study of the sensor was carried out with acetone, ammonia, carbon monoxide, hydrogen peroxide and propanol. It demonstrated high selectivity towards the interfering gases and high humid condition. Au-decorated ZnO NRs exhibited very low detection limit $\sim 6.6$ppb, which is attractive for biomedical applications.

Designing and developing sensitive electrochemical sensors have always been paid attention to achieve the accurate detection of ammonia–nitrogen in the aqueous environment. Herein, a two-step electrodeposition route was used to achieve a Ni foam-supported polypyrrole nanospheres and Pt nanostars sensing electrode (Pt-PPy-Ni foam) for ammonia–nitrogen detection. After controlling the deposition time of Pt nanostars, the optimal Pt-PPy-Ni foam electrode exhibited greater electrocatalytic ability for ammonia oxidation reaction with a current density of 41.73 mA cm${}^{-2}$ than that of Pt-Ni foam. This enhanced electrocatalytic ability could be attributed to the excellent adsorption of polypyrrole nanospheres for ammonia and the great catalytic activity of Pt nanostars for the ammonia oxidation reaction. This Pt-PPy-Ni foam electrode showed great detection performances with a sensitivity of 0.013 mA $\mu$M${}^{-1}$, and a detection limit of 8.72 $\mu$M. Moreover, accepted results were obtained for the recovery measurements of lake and seawater samples with recoveries from 101.05% to 102.27% and 90.73% to 91.70%. In addition, Pt-PPy-Ni foam sensor exhibited good anti-interference ability with low current charges, reproducibility (relative standard deviation = 1.58%) and stability (relative standard deviation = 6.11%), showing a great application potential.

The much thicker intrinsic absorption layer (IAL) in normal-incidence Ge-on-Si photodetectors (NIPD) usually causes a contradiction between responsivity and bandwidth. In response to this issue, here, we simulate the design of an NIPD with geranium (Ge) layers based on a “fishnet” metasurface, leading to a reduced device thickness as thin as 380nm. The optical simulation results show that the light field can be perfectly localized in the 210nm IAL, and the absorptivity is as high as 99.45% at 1550nm, which is even better than bulk materials. Moreover, the electrical simulation results suggest that the horizontal size of the photosensitive region can be reduced to 11.2 $\mu$m, while the responsivity of the photodetector is close to 1 A/W at −1V bias voltage, which is nearly 23 times that of a bulk device with the same thickness, and the 3dB bandwidth is up to 40GHz, which can be compared with waveguide photodetectors. Besides, this device also demonstrates a high signal-to-noise ratio with a low dark current of 28.68 nA, making it an excellent PD for opto-electrical communication.

With the continuous development of antibacterial nanotechnology, nanoparticle-mediated photothermal therapy (PTT) could treat dental implant bacterial infections. Here, a carbon quantum dots (CQDs) loading penicillin (CQDs@penicillin) was constructed as an innovative nanoplatforms to confer promising PTT and delivery of antibiotics. In this nanosystem, CQDs with distinct antibacterial application performance were utilized as an ideal nanocarrier for drug loading, evoking photothermal effects to generate heat under near-infrared (NIR) irradiation. The delivery of penicillin could induce damage to the bacterial cell wall and play a bactericidal effect during the reproduction period of bacterial cells. The antibacterial effects in vitro implied that CQDs@penicillin could significantly kill bacterial cells without severe toxicity. This study proposes a feasible therapeutic strategy for the delivery of antibiotics to dental implant bacterial infections and simultaneously the PTT effect.