Physicochemical, Antibacterial Properties, and Compatibility of ZnO-NP/Chitosan/β-Glycerophosphate Composite Hydrogels

( Pingping Huang ),( Wen Su ),( Rui Han ),( Hao Lin ),( Jing Yang ),( Libin Xu ),( Lei Ma ) 한국미생물생명공학회 2022 Journal of microbiology and biotechnology Vol.32 No.4

In this study we aimed to develop novel ZnO-NP/chitosan/β-glycerophosphate (ZnO-NP/CS/β-GP) antibacterial hydrogels for biomedical applications. According to the mass fraction ratio of ZnO-NPs to chitosan, mixtures of 1, 3, and 5% ZnO-NPs/CS/β-GP were prepared. Using the test-tube inversion method, scanning electron microscopy and Fourier-transform infrared spectroscopy, the influence of ZnO-NPs on gelation time, chemical composition, and cross-sectional microstructures were evaluated. Adding ZnO-NPs significantly improved the hydrogel's antibacterial activity as determined by bacteriostatic zone and colony counting. The hydrogel's bacteriostatic mechanism was investigated using live/dead fluorescent staining and scanning electron microscopy. In addition, crystal violet staining and MTT assay demonstrated that ZnO-NPs/CS/β-GP exhibited good antibacterial activity in inhibiting the formation of biofilms and eradicating existing biofilms. CCK-8 and live/dead cell staining methods revealed that the cell viability of gingival fibroblasts (L929) cocultured with hydrogel in each group was above 90% after 24, 48, and 72 h. These results suggest that ZnO-NPs improve the temperature sensitivity and bacteriostatic performance of chitosan/β-glycerophosphate (CS/β-GP), which could be injected into the periodontal pocket in solution form and quickly transformed into hydrogel adhesion on the gingiva, allowing for a straightforward and convenient procedure. In conclusion, ZnO-NP/CS/β-GP thermosensitive hydrogels could be expected to be utilized as adjuvant drugs for clinical prevention and treatment of peri-implant inflammation.

Bayesian Approach for Two-Phase Degradation Data Based on Change-Point Wiener Process With Measurement Errors

Wang, Pingping,Tang, Yincai,Bae, Suk Joo,Xu, Ancha Institute of Electrical and Electronics Engineers 2018 IEEE transactions on reliability Vol. No.

<P>Degradation test is an effective method in assessing product reliability when measurements of degradation leading to failure can be observed. The accuracy of reliability inference in degradation analysis highly depends on the fitted model to the observed degradation data. Sometimes, observed degradation paths of the products exhibit multiphase pattern over the testing period. In this paper, we propose a change-point Wiener process with measurement errors (CPWPME) to fit two-phase degradation paths of organic light-emitting diodes (OLEDs). We assume the unit-specific parameters of the CPWPME model by using hierarchical Bayesian method. Based upon the proposed approach, the failure-time distribution and the remaining useful life distribution along with mean time to failure and mean residual life function are derived in closed form. A simulation study shows the utility of the proposed CPWPME model and the validity of the hierarchical Bayesian approach for the degradation data possessing two-phase degradation characteristics. In the analysis of OLED degradation data, the hierarchical Bayesian CPWPME model provides higher modeling flexibility and prediction power for future testing units than existing three degradation models.</P>

Fast pulse current control of multiphase pulse power supply converters using feedback linearization

Zhibao Yuan,Pingping Wen,Haiping Xu,Zengquan Yuan 전력전자학회 2021 JOURNAL OF POWER ELECTRONICS Vol.21 No.12

To improve the performance of multiphase pulse power supply (MPPS) converters, a current control strategy based on feedback linearization (FL) is proposed for flat-top current control by using an average model of the MPPS converter in thisstudy. A nonlinear state function model of a MPPS converter is presented and transformed to a linearized and decoupled form with the input–output feedback linearization technique. Based on the linearized system, simple linear controllers are designed to regulate the current among different phases and output current of the MPPS, which significantly reduces the difficulty in controller design and tuning. Moreover, a pre-charge method is adopted to improve current rising edge, which improves the current response of the flat-top current control. To test its effectiveness, the proposed strategy is employed in a 10 kW MPPS prototype. When compared to the conventional PI-based current control for MPPS converters, the proposed strategy provides a better dynamic performance in terms of current regulation and its flexibility can be extended to any of the paralleled phases of a MPPS system.

First-principles study of dissociation processes of O2 molecular on the Al (111) surface

Shiyang Sun,Pingping Xu,Yuan Ren,Xin Tan,Geyang Li 한국물리학회 2018 Current Applied Physics Vol.18 No.12

The trajectories of adsorption and dissociation process of O2 on the Al (111) surface were studied by the spinpolarized ab initio molecular dynamics method, and the adsorption activation energy was clarified by the NEB method with hybrid functionals. Three typical dissociation trajectories were found through simulation of O2 molecule at different initial positions. When vertically approaches to the Al surface, the O2 molecule tends to rotate, and the activation energy is 0.66eV. If O2 molecule does not rotate, the activation energy will increase to 1.43 eV, and it makes the O atom enter the Al sublayer eventually. When the O2 molecules parallel approach to the Al surface, there is no activation energy, due to the huge energy released during the adsorption process.

Panax ginseng total protein promotes proliferation and secretion of collagen in NIH/3T3 cells by activating extracellular signal-related kinase pathway

Chen, Xuenan,Wang, Manying,Xu, Xiaohao,Liu, Jianzeng,Mei, Bing,Fu, Pingping,Zhao, Daqing,Sun, Liwei The Korean Society of Ginseng 2017 Journal of Ginseng Research Vol.41 No.3

Background: Recently, protein from ginseng was studied and used for the treatment of several kinds of diseases. However, the effect of ginseng total protein (GTP) on proliferation and wound healing in fibroblast cells remains unclear. Methods: In this study, cell viability was analyzed using the MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] assay. Cell cycle distribution was analyzed by flow cytometer. The levels of transforming growth factor ${\beta}1$, vascular endothelial growth factor, and collagens were analyzed by enzyme-linked immunosorbent assay and immunofluorescence staining. The expressions of cyclin A, phosphorylation of extracellular signal-related kinase (p-ERK1/2), and ERK1/2 were analyzed by Western blotting. Results: Our results showed that GTP promoted cell proliferation and increased the percentage of cells in S phase through the upregulation of cyclin A in NIH/3T3 cells. We also found that GTP induced the secretion of type I collagen, and promoted the expression of other factors that regulate the synthesis of collagen such as transforming growth factor ${\beta}1$ and vascular endothelial growth factor. In addition, the phosphorylation of ERK1/2 at Thr202/Tyr204 was also increased by GTP. Conclusion: Our studies suggest that GTP promoted proliferation and secretion of collagen in NIH/3T3 cells by activating the ERK signal pathway, which shed light on a potential function of GTP in promoting wound healing.

Multi-loop current control strategy based on predictive control for multiphase pulse power supplies

Yuan, Zhibao,Wen, Pingping,Xu, Haiping,Yuan, Zengquan The Korean Institute of Power Electronics 2021 JOURNAL OF POWER ELECTRONICS Vol.21 No.3

For high-power quasi-continuous laser drivers, the switched pulse power supply (PPS) is a promising technique due to its higher efficiency when compared with linear drivers. However, there are some digital control challenges with high precision, fast response and zero overshoot during the flat-top current stage. To promote the use of a switched PPS, this paper proposes a digital control strategy based on predictive current control under a multiphase PPS converter circuit. The key of the proposed control strategy is that predictive inner current control is only used for the master phase circuit. Meanwhile, the current sharing control is used for balancing the phase currents, and the setting outer current controller is used for keeping the whole converter control system stable and robust. Furthermore, to obtain fast and precise current tracking, a predictive average current control independent from the load values is derived. Moreover, a reducing gain method is applied to guarantee the stability of the inner current control. When compared with the conventional multiphase control, the proposed strategy possesses a faster dynamic response and a higher accuracy. In addition, it is more flexible under digital control implementation. A 360 W dual-interleaved PPS prototype is utilized for verifying the effectiveness of the proposed control strategy.

Fabrication of Stiffness Gradient Nanocomposite Hydrogels for Mimicking Cell Microenvironment

Yan Hu,Yang Yang,Fei Tian,Pingping Xu,Rongcheng Du,Xuehuan Xia,Shimei Xu 한국고분자학회 2021 Macromolecular Research Vol.29 No.7

It has attracted much attention to develop a gradient hydrogel for real mimic of the extracellular matrix. Despite simplicity and ease of electrophoresis preparation method, some drawbacks limit the application of the method including toxic organic crosslinker residual, specific ionic monomer types, as well as narrow gradient gaps. In this work, we successfully prepared gradiently crosslinked nonionic PNIPAm/Laponite nanocomposite (NC) hydrogels with controllable gradient structures by adjusting the intensity of the direct current electric field. The results showed that the stiffness, surface property and thermosensitivity of the hydrogel changed with gradient distributions of Laponite. The average stiffness gradients varied from 0.18 kPa/mm, 0.41 kPa/mm to 1.28 kPa/mm by simply adjusting the intensity of the direct current electric field from 0.13 V/mm, 0.20 V/mm to 0.27 V/mm accordingly. The stiffness reached in a range of 13.8~33.0 kPa. The growth behaviors of human cervical cancer cells (HeLa cells) on the gradient NC hydrogel surface were discussed. Spreading and proliferation, as well as morphology of HeLa cells were closely related to the stiffness of the gradient NC hydrogels. This work develops a stiffness-controllable gradient NC hydrogel and opens up a new insight into the better understanding of cells behaviors in different tissues and organs in vivo.

Panax ginseng total protein promotes proliferation and secretion of collagen in NIH/3T3 cells by activating extracellular signal-related kinase pathway

Xuenan Chen,Manying Wang,Xiaohao Xu,Jianzeng Liu,Bing Mei,Pingping Fu,Da-Qing Zhao,Liwei Sun 고려인삼학회 2017 Journal of Ginseng Research Vol.41 No.3

Background: Recently, protein from ginseng was studied and used for the treatment of several kinds of diseases. However, the effect of ginseng total protein (GTP) on proliferation and wound healing in fibroblast cells remains unclear. Methods: In this study, cell viability was analyzed using the MTT [3-(4,5-dimethylthiazol-2-yl)-2,5- diphenyltetrazolium bromide] assay. Cell cycle distribution was analyzed by flow cytometer. The levels of transforming growth factor b1, vascular endothelial growth factor, and collagens were analyzed by enzyme-linked immunosorbent assay and immunofluorescence staining. The expressions of cyclin A, phosphorylation of extracellular signal-related kinase (p-ERK1/2), and ERK1/2 were analyzed byWestern blotting. Results: Our results showed that GTP promoted cell proliferation and increased the percentage of cells in S phase through the upregulation of cyclin A in NIH/3T3 cells. We also found that GTP induced the secretion of type I collagen, and promoted the expression of other factors that regulate the synthesis of collagen such as transforming growth factor b1 and vascular endothelial growth factor. In addition, the phosphorylation of ERK1/2 at Thr202/Tyr204 was also increased by GTP. Conclusion: Our studies suggest that GTP promoted proliferation and secretion of collagen in NIH/3T3 cells by activating the ERK signal pathway, which shed light on a potential function of GTP in promoting wound healing.

Expression of RUNX2/LAPTM5 in the Induction of MC3T3-e1 Mineralization and Its Possible Relationship with Autophagy

Xing Lei,Li Yanqin,Li Wenhao,Liu Rong,Geng Yuanming,Ma Weiqun,Qiao Yu,Li Jianwen,Lv Yingtao,Fang Ying,Xu Pingping 한국조직공학과 재생의학회 2022 조직공학과 재생의학 Vol.19 No.6

BACKGROUND: The study aims to correlate osteogenesis with autophagy during the mineralization induction of MC3T3-e1 through exploring the expression of runt-related transcription factor 2 (RUNX2)/lysosomal-associated transmembrane protein 5 (LAMPT5). METHODS: The induction of mineralization in MC3T3-e1 was followed by detecting the expressions of osteogenesisrelated indexes such as RUNX2, alkaline phosphatase (ALP), osteocalcin (OCN), and LAPTM5 using RT-qPCR and Western blot from 0 to 14 days. Transmission electron microscope was utilised in visualizing the alterations of autophagosomes, which was followed by immunofluorescence detecting the subcellular localization of autophagy-related index sequestosome 1 (P62) and microtubule-associated protein 1 light 3 (LC3) protein and scrutinising the expression of P62 mRNA and P62 and LC3 proteins. RESULTS: Induction of MC3T3-e1 mineralization demonstrated an increased expression of osteogenesis-related indicators such as RUNX2, ALP, OCN, and LAPTM5 (p\0.05), as evident from the results of RT-qPCR and Western blot. Meanwhile, the expression of autophagosomes increased one day after mineralization induction and then experienced a gradual decline, and enhanced expression of LC3 protein was noted on days 1–2 of mineralization induction but was then followed by a corresponding reduce. In contrast, a continuous increase was reported in the expression of P62 mRNA and protein, respectively (p\0.05). Up- and down-regulating RUNX2/LAPTM5 expression alone confirmed the aforementioned results. CONCLUSION: It was therefore proposed that RUNX2 may be responsible for an early increase and then a gradual decrease in LAPTM5-mediated autophagy through the regulation of its high expression. Meanwhile, increased LAPTM5 expression in osteogenic mineralization presumed that RUNX2/LAPTM5 promoted autophagy and osteogenic expression, which may play a bridging role in the regulation of autophagy and osteogenesis.