Search

Abstract The inactivation of natural enzymes by radiation poses a great challenge to their applications for radiotherapy. Single-atom nanozymes (SAzymes) with high structural stability under such extreme conditions become a promising candidate for replacing natural enzymes to shrink tumors. Here, we report a CuN3-centered SAzyme (CuN3-SAzyme) that exhibits higher peroxidase-like catalytic activity than a CuN4-centered counterpart, by locally regulating the coordination environment of single copper sites. Density functional theory calculations reveal that the CuN3 active moiety confers optimal H2O2 adsorption and dissociation properties, thus contributing to high enzymatic activity of CuN3-SAzyme. The introduction of X-ray can improve the kinetics of the decomposition of H2O2 by CuN3-SAzyme. Moreover, CuN3-SAzyme is very stable after a total radiation dose of 500 Gy, without significant changes in its geometrical structure or coordination environment, and simultaneously still retains comparable peroxidase-like activity relative to natural enzymes. Finally, this developed CuN3-SAzyme with remarkable radioresistance can be used as an external field-improved therapeutics for enhancing radio-enzymatic therapy in vitro and in vivo. Overall, this study provides a paradigm for developing SAzymes with improved enzymatic activity through local coordination manipulation and high radioresistance over natural enzymes, for example, as sensitizers for cancer therapy.

Abstract In this study, we successfully constructed the new graphene oxide/poly-L-lactic acid (GO/PLLA) nanofiber scaffolds with a hydrophilic surface and porous network structure that were highly favorable for cell infiltration. When employed these new nanofiber scaffolds for a wide range of tissue engineering applications, it was expected to promote graft tissue survival and angiogenesis. The new GO/PLLA nanofiber scaffold with an appropriate concentration of 1.0 wt% was applied for the restoration of ovarian function and reserve in mice with primary ovarian insufficiency (POI). After co-transplanting the normal ovarian cortex loaded on these new nanomaterials into the in situ ovarian tissue of POI mice, the fusion of transplanted ovarian cortex with damaged ovarian tissue was improved, as well as the ovarian function and the follicle numbers. Moreover, angiogenesis was observed clearly and proved to exist in the transplanted tissue and nanomaterials, with the most conspicuous effect after co-transplantation with 1.0 wt% GO/PLLA nanofiber scaffold. In addition, nitric oxide (NO) production by phosphorylated endothelial nitric oxide synthase (p-eNOS) in vivo was proven to be involved in the effect of GO and PLLA on the improved survival rate of the transplanted ovarian cortex. This study provides a new method for the fertility preservation of ovarian tissue cryopreservation and transplantation, as well as a new strategy for the transplantation of other organs.

A lot of adaptive signal decomposition methods have been applied for nonstationary DPMIG electrical signals as they are always affected by noise. Recently, to solve the problems of former methods caused by the Gibbs phenomenon and the calculation of extremas when dealing with broadband electrical signals such as square signals and sawtooth signals with “sharp corners”, broadband mode decomposition (BMD) method was proposed and the application of the algorithm showed a good performance. The main idea of BMD is searching in the associative dictionary contains both broadband and narrowband signals using a regulated differential operator as the optimal object. However, when applied to a broadband signal interfered by strong noise, as the relative bandwidth is not small enough, the BMD algorithm may treat the broadband signal to be several narrowband components. Therefore, modulated broadband mode decomposition (MBMD) is proposed in this paper to denoise broadband electrical signals based on modulated differential operator. By multiplying a high frequency mono-frequency signal, the relative bandwidth of the effective broadband signal is translated to be far less than 1, and the broadband signals are treated as approximate broadband signals to get more accurate decomposition results. For the further feature extraction of the electrical signals, locality preserving projection (LPP) is applied combined with MBMD. The effectiveness of the proposed method is testified by simulation and experimental signals, results show that it is effective when drawing broadband feature from noise, as well as is adaptive for the feature extraction of double pulse metal inert gas welding.

Adaptive sparsest narrow-band decomposition is the most sparse solution to search for signals in the over-complete dictionary library containing intrinsic mode functions, which transform the signal decomposition into an optimization problem, but the calculation accuracy must be improved in the case of strong noise interference. Therefore, in combination with the algorithm of the complementary ensemble empirical mode decomposition, a new method of the complementary ensemble adaptive sparsest narrow-band decomposition is obtained. In the complementary ensemble adaptive sparsest narrow-band decomposition, the white noise opposite to the paired symbol is added to the target signal to reduce the reconstruction error and realize the adaptive decomposition of the signal in the process of optimizing the filter parameters. The analysis results of the simulation and experimental data show this method is superior to complementary ensemble empirical mode decomposition and adaptive sparsest narrow-band decomposition in inhibiting the mode confusion, endpoint effect, improving the component orthogonality and accuracy, and effectively identifying the gears fault types.

With the increasing application of nanomaterials in aerospace technology, the long-term space exposure to nanomaterials especially in the space full of radiation coupled with microgravity condition has aroused great health concerns of the astronauts. However, few studies have been conducted to assess these effects, which are crucial for seeking the possible intervention strategy. Herein, using a random positioning machine (RPM) to simulate microgravity, we investigated the behaviors of cells under simulated microgravity and also evaluated the possible toxicity of titanium dioxide nanoparticles (TiO2 NPs), a multifunctional nanomaterial with potential application in aerospace. Pulmonary epithelial cells A549 were exposed to normal gravity (1 g) and simulated gravity (~10−3 g), respectively. The results showed that simulated microgravity had no significant effect on the viability of A549 cells as compared with normal gravity within 48 h. The effects of TiO2 NPs exposure on cell viability and apoptosis were marginal with only a slightly decrease in cell viability and a subtle increase in apoptosis rate observed at a high concentration of TiO2 NPs (100 μg/mL). However, it was observed that the exposure to simulated microgravity could obviously reduce A549 cell migration compared with normal gravity. The disruption of F-actin network and the deactivation of FAK (Tyr397) might be responsible for the impaired mobility of simulated microgravity-exposed A549 cells. TiO2 NPs exposure inhibited cell migration under two different gravity conditions, but to different degrees, with a milder inhibition under simulated microgravity. Meanwhile, it was found that A549 cells internalized more TiO2 NPs under normal gravity than simulated microgravity, which may account for the lower cytotoxicity and the lighter inhibition of cell migration induced by the same exposure concentration of TiO2 NPs under simulated microgravity at least partially. Our study has provided some tentative information on the effects of TiO2 NPs exposure on cell behaviors under simulated microgravity.