Publications by authors named "Da Xiong"

10 Publications

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Hierarchically Microstructure-Bioinspired Flexible Piezoresistive Bioelectronics.

ACS Nano 2021 Jun 15. Epub 2021 Jun 15.

Key Laboratory of Advanced Technologies of Materials (Ministry of Education), School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu 610031, P. R. China.

The naturally microstructure-bioinspired piezoresistive sensor for human-machine interaction and human health monitoring represents an attractive opportunity for wearable bioelectronics. However, due to the trade-off between sensitivity and linear detection range, obtaining piezoresistive sensors with both a wide pressure monitoring range and a high sensitivity is still a great challenge. Herein, we design a hierarchically microstructure-bioinspired flexible piezoresistive sensor consisting of a hierarchical polyaniline/polyvinylidene fluoride nanofiber (HPPNF) film sandwiched between two interlocking electrodes with microdome structure. Ascribed to the substantially enlarged 3D deformation rates, these bioelectronics exhibit an ultrahigh sensitivity of 53 kPa, a pressure detection range from 58.4 to 960 Pa, a fast response time of 38 ms, and excellent cycle stability over 50 000 cycles. Furthermore, this conformally skin-adhered sensor successfully demonstrates the monitoring of human physiological signals and movement states, such as wrist pulse, throat activity, spinal posture, and gait recognition. Evidently, this hierarchically microstructure-bioinspired and amplified sensitivity piezoresistive sensor provides a promising strategy for the rapid development of next-generation wearable bioelectronics.
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http://dx.doi.org/10.1021/acsnano.1c01606DOI Listing
June 2021

Understanding the Percolation Effect in Triboelectric Nanogenerator with Conductive Intermediate Layer.

Research (Wash D C) 2021 4;2021:7189376. Epub 2021 Feb 4.

Key Laboratory of Advanced Technologies of Materials, Ministry of Education, School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu 610031, China.

Introducing the conductive intermediate layer into a triboelectric nanogenerator (TENG) has been proved as an efficient way to enhance the surface charge density that is attributed to the enhancement of the dielectric permittivity. However, far too little attention has been paid to the companion percolation, another key element to affect the output. Here, the TENG with MXene-embedded polyvinylidene fluoride (PVDF) composite film is fabricated, and the dependence of the output capability on the MXene loading is investigated experimentally and theoretically. Specifically, the surface charge density mainly depends on the dielectric permittivity at lower MXene loadings, and in contrast, the percolation becomes the degrading factor with the further increase of the conductive loadings. At the balance between the dielectric and percolation properties, the surface charge density of the MXene-modified TENG obtained 350% enhancement compared to that with the pure PVDF. This work shed new light on understanding the dielectric and percolation effect in TENG, which renders a universal strategy for the high-performance triboelectronics.
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http://dx.doi.org/10.34133/2021/7189376DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7881766PMC
February 2021

Understanding the Potential Screening Effect through the Discretely Structured ZnO Nanorods Piezo Array.

Nano Lett 2020 Jun 20;20(6):4270-4277. Epub 2020 May 20.

Key Laboratory of Advanced Technologies of Materials (Ministry of Education), School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu 610031, China.

The potential screening effect of one-dimensional ZnO nanorods from carriers has been theoretically proved to severely limit its piezoelectricity, but its exact mechanism needs to be further revealed in experiments to guide the design of piezoelectric semiconductors. Here, a discretely structured design was proposed to prevent the free carriers from tunneling among adjacent ZnO nanorods for suppressing the screening effect. Piezoresponse force microscope and finite element analysis were employed in combination to uncover the underlying mechanism in experiment. Further, the output voltage of this discretely structured device was 1.62 times higher than that of the nondesigned device, which clearly authenticates this suppression behavior. Besides, this design prompts an unexpected improvement in flexibility, where the flexural modulus of this piezo-film was reduced by 35.74%. Notably, this work opens a new way to understand the potential screening effect, as expected, and to advance the development of piezo-electronics toward better piezoelectricity and more excellent flexibility.
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http://dx.doi.org/10.1021/acs.nanolett.0c00793DOI Listing
June 2020

Unraveling and Regulating Self-Discharge Behavior of TiCT MXene-Based Supercapacitors.

ACS Nano 2020 Apr 23;14(4):4916-4924. Epub 2020 Mar 23.

Key Laboratory of Advanced Technologies of Materials (Ministry of Education), School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu 610031, P.R. China.

Rich chemistry and surface functionalization provide MXenes enhanced electrochemical activity yet severely exacerbate their self-discharge behavior in supercapacitors. However, this self-discharge behavior and its related mechanism are still remaining issues. Herein, we propose a chemically interface-tailored regulation strategy to successfully unravel and efficiently alleviate the self-discharge behavior of TiCT MXene-based supercapacitors. As a result, TiCT MXenes with fewer F elements (∼0.65 atom %) show a positive self-discharge rate decline of ∼20% in comparison with MXenes with higher F elements (∼8.09 atom %). Such decline of the F elements can highly increase tight-bonding ions corresponding to an individual self-discharge process, naturally resulting in a dramatic 50% increase of the transition potential (). Therefore, the mixed self-discharge rate from both tight-bonding (contain fewer F elements) and loose-bonding ions (contain more F elements) is accordingly lowered. Through chemically interface-tailored engineering, the significantly changed average oxidation state and local coordination information on MXene affected the interaction of ion counterparts, which was evidently revealed by X-ray absorption fine structures. Theoretically, this greatly improved self-discharge performance was proven to be from higher adsorption energy between the interface of the electrode and the electrolyte by density functional theory. Therefore, this chemically interface-tailored regulation strategy can guide the design of high-performance MXene-based supercapacitors with low self-discharge behavior and will promote its wider commercial applications.
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http://dx.doi.org/10.1021/acsnano.0c01056DOI Listing
April 2020

Upregulation of miR‑423 improves autologous vein graft restenosis via targeting ADAMTS‑7.

Int J Mol Med 2020 Feb 5;45(2):532-542. Epub 2019 Dec 5.

Department of Cardiovascular Surgery, The First People's Hospital of Yunnan Province, The Affiliated Hospital of Kunming University of Science and Technology, Kunming, Yunnan 650000, P.R. China.

Coronary artery bypass graft (CABG) is one of the primary methods of treating coronary heart disease (CHD); however, vein graft restenosis is a major limiting factor of the effectiveness of CABG. Emerging evidence has indicated that miR‑423 is associated with vascular diseases. Additionally, upregulation of a disintegrin and metalloproteinase with thrombospondin motifs‑7 (ADAMTS‑7) contributes to neointima formation by promoting the proliferation and migration of vascular smooth muscle cells and inhibiting the proliferation and migration of endothelial cells. The aim of the present study was to examine the effects of miR‑423 target, ADAMTS‑7, on regulating vein graft disease and identify novel biomarkers for use in therapy of vein graft failure (VGF). Aberrant expression of miR‑423 in plasma of patients with CHD prior to and following CABG confirms that miR‑423 may be a suitable target for preventing VGF. Furthermore, a dual‑luciferase reporter gene assay indicated that miR‑423 directly interacted with ADAMTS‑7 and suppressed its expression. Ectopic expression of miR‑423 suppressed ADAMTS‑7, resulting in decreased proliferation and migration rates of human umbilical vein smooth muscle cells by targeting ADAMTS‑7, but resulted in increased proliferation and migration of human umbilical vein endothelial cells in vitro. Overexpression of miR‑423 also enhanced re‑endothelialization and decreased neointimal formation in a rat vein graft model. In conclusion, the results of the present study demonstrated that the miR‑423/ADAMTS‑7 axis may possess potential clinical value for the prevention and treatment of restenosis in patients with CHD following CABG.
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http://dx.doi.org/10.3892/ijmm.2019.4419DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6984782PMC
February 2020

Surface pre-optimization of a mixed halide perovskite toward high photoluminescence quantum yield in the blue spectrum range.

Nanoscale 2019 Aug;11(32):15206-15215

Key Laboratory of Advanced Technologies of Materials (Ministry of Education), School of Materials Science and Engineering, State Key Laboratory of Traction Power, Southwest Jiaotong University, Chengdu 610031, PR China.

The photoluminescence quantum yields (PLQYs) of all-inorganic halide perovskites in the green and red spectral ranges have approached over 90%, overwhelmingly arousing burgeoning interests for creating a revolution in next-generation high-definition displays. However, obtaining pure blue-emitting perovskites with high PLQYs still remains a challenge. Herein, we designed a novel strategy to pre-optimize CsPbCl3 quantum dots (QDs) using praseodymium(iii) chloride (PrCl3), and then efficient blue-emitting CsPbBrxCl3-x QDs were obtained through halide exchange between the optimized CsPbCl3 and efficient CsPbBr3 QDs. Specifically, the PrCl3 optimization simultaneously and efficiently passivated the surface vacancy defects and appropriately reduced the surface long-chain organic ligands of the CsPbCl3 QDs, synergistically eliminating the deep trap states, and hence considerably suppressing nonradiative recombination. As a result, the radiative recombination rate was enhanced by more than one order of magnitude from 4.3 to 79 μs-1. Benefiting from this, the blue-emitting CsPbBrxCl3-x QDs exhibited an admirable PLQY of up to 89%, which is competitive compared with that of the state-of-the-art red and green-emitting perovskites. This strategy provides a unique understanding regarding the low PLQY of blue-emitting perovskites and an efficient method to boost it, which is especially attractive for constructing efficient blue and white light-emitting diodes.
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http://dx.doi.org/10.1039/c9nr05217hDOI Listing
August 2019

Endothelial retinoblastoma protein reduces abdominal aortic aneurysm development via promoting DHFR/NO pathway-mediated vasoprotection.

Mol Cell Biochem 2019 Oct 18;460(1-2):29-36. Epub 2019 Jun 18.

Department of Cardiovascular Surgery, The First Peoples' Hospital of Yunnan Province, No. 157, Jinbi road, Kunming, Yunnan, People's Republic of China.

Cardiovascular disease (CVD) is a major cause of global mortality. The proper functioning of the endothelial layer of arteries is crucial to cardiovascular health. Retinoblastoma protein (Rb), encoded by the Rb1 gene, has been shown to offer vasoprotective effects. Herein, we investigated endothelial Rb's effects on arterial function using an endothelial-specific conditional Rb1 knockout (Rb cKO) mouse model. We found that Rb deficiency reduced dihydrofolate reductase (DHFR) activity and downstream NO production in mouse aortic endothelial cells and blocked arterial vasodilation in an endothelial DHFR-dependent manner. Rb deficiency also increased phenylephrine-triggered arterial vasoconstriction, BP levels, and pathological aortic remodeling without significantly affecting prostanoid synthesis. Employing an angiotensin II (AngII)-stimulated apolipoprotein E knockout (apoE -/-) mice fed a standard, non-atherogenic diet, Rb deficiency increased aortic diameter, stimulated abdominal aortic aneurysm (AAA) development, and reduced survival. These pathological responses to Rb deficiency in AngII-stimulated apoE-/- mice were rescued by DHFR overexpression. Cumulatively, our findings reveal that endothelial Rb positively impacts arterial function by supporting vasoprotective endothelial DHFR/NO pathway activity, leading to reduced AAA development.
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http://dx.doi.org/10.1007/s11010-019-03567-yDOI Listing
October 2019

A piezo-phototronic enhanced serrate-structured ZnO-based heterojunction photodetector for optical communication.

Nanoscale 2019 Feb;11(6):3021-3027

Key Laboratory of Advanced Technologies of Materials (Ministry of Education), School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu 610031, China.

ZnO-based heterojunction photodetectors have been widely used in various fields such as optical imaging and health monitoring. As for the traditional planar heterojunction interface, their limited optical absorption will place restrictions on the full photoelectric potential of ZnO nanorods, which severely restrains the commercial applications of ZnO-based photodetectors. Herein, using an intrinsically octahedral structure of p-type Cu2O and one-dimensional ZnO arrays, the newly designed serrate-structured heterojunction was constructed, whose unique serrate-structured interface of ZnO/Cu2O is highly conducive to the aggrandizing of optical absorption. The as-fabricated photodetector could achieve a high on/off ratio up to 1000 and an optimum photocurrent of 24.90 μA under 1.41 mW mm-2 (405 nm) illumination without bias voltage, which was 2.5 times higher than that of the planar-structured photodetector, and the response time was as quick as 1.6 ms. When the additional external strain was 0.39%, the performance was dramatically enhanced more than 5 times due to the synergism of the piezo-phototronic effect and the serrate-structured design. Based on this, we successfully developed designed photodetector arrays with an excellent optical communication performance of transmitting information. Prospectively, this kind of unique serrate-structured heterojunction design will open up a possible opportunity for high performance photodetectors based on structural engineering.
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http://dx.doi.org/10.1039/c8nr09418gDOI Listing
February 2019

An enhanced low-frequency vibration ZnO nanorod-based tuning fork piezoelectric nanogenerator.

Nanoscale 2018 Jan;10(2):843-847

Key Laboratory of Advanced Technologies of Materials (Ministry of Education), School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu 610031, China.

In this paper, a piezoelectric nanogenerator (PENG) based on a tuning fork-shaped cantilever was designed and fabricated, aiming at harvesting low frequency vibration energy in the environment. In the PENG, a tuning fork-shaped elastic beam combined with ZnO nanorods (NRs), instead of conventional rectangular cantilever beams, was adopted to extract vibration energy. Benefiting from the high flexibility and the controllable shape of the substrate, this PENG was extremely sensitive to vibration and can harvest weak vibration energy at a low frequency. Moreover, a series of simulation models were established to compare the performance of the PENG with that of different shapes. On this basis, the experimental results further verify that this designed energy harvester could operate at a low frequency which was about 13 Hz. The peak output voltage and current could respectively reach about 160 mV and 11 nA, and a maximum instantaneous peak power of 0.92 μW cm across a matched load of 9 MΩ was obtained. Evidently, this newly designed PENG could harvest vibration energy at a lower frequency, which will contribute to broaden the application range of the PENG in energy harvesting and self-powered systems.
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http://dx.doi.org/10.1039/c7nr07325aDOI Listing
January 2018

A novel vaccine delivery system: biodegradable nanoparticles in thermosensitive hydrogel.

Growth Factors 2011 Dec 10;29(6):290-7. Epub 2011 Oct 10.

State Key Laboratory of Biotherapy, West China Hospital, West China Medical School, and School of Life Sciences, Sichuan University, Chengdu, People's Republic of China.

In this work, a novel vaccine delivery system, biodegradable nanoparticles (NPs) in thermosensitive hydrogel, was investigated. Human basic fibroblast growth factor (bFGF)-loaded NPs (bFGF-NPs) were prepared, and then bFGF-NPs were incorporated into thermosensitive hydrogel to form bFGF-NPs in a hydrogel composite (bFGF-NPs/hydrogel). bFGF-NPs/hydrogel was an injectable sol at ambient temperature, but was converted into a non-flowing gel at body temperature. The in vitro release profile showed that bFGF could be released from bFGF-NPs or bFGF-NPs/hydrogel at an extended period, but the release rate of bFGF-NPs/hydrogel was much lower. In vivo experiments suggested that immunogenicity of bFGF improved significantly after being incorporated into the NPs/hydrogel composite, and strong humoral immunity was maintained for longer than 12 weeks. Furthermore, an in vivo protective anti-tumor immunity assay indicated that immunization with bFGF-NPs/hydrogel could induce significant suppression of the growth and metastases of tumors. Thus, the NPs/hydrogel composite may have great potential application as a novel vaccine delivery system.
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http://dx.doi.org/10.3109/08977194.2011.624517DOI Listing
December 2011
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