Publications by authors named "Jinglei Yang"

42 Publications

Interdigitated Three-Dimensional Heterogeneous Nanocomposites for High-Performance Mechanochromic Smart Membranes.

ACS Nano 2021 Nov 19. Epub 2021 Nov 19.

Department of Materials Science and Engineering, KAIST Institute for the Nanocentury, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Republic of Korea.

Mechanochromic smart membranes capable of optical modulation have great potential in smart windows, artificial skins, and camouflage. However, the realization of high-contrast optical modulation based on light scattering activated at a low strain remains challenging. Here, we present a strategy for designing mechanochromic scattering membranes by introducing a Young's modulus mismatch between the two interdigitated polydimethylsiloxane phases with weak interfaces in a periodic three-dimensional (3D) structure. The refractive index-matched interfaces of the nanocomposite provide a high optical transparency of 93%. Experimental and computational studies reveal that the 3D heterogeneity facilitates the generation of numerous nanoscale debonds or "nanogaps" at the modulus-mismatching interfaces, enabling incident light scattering under tension. The heterogeneous scatterer delivers both a high transmittance contrast of >50% achieved at 15% strain and a maximum contrast of 82%. When used as a smart window, the membrane demonstrates effective diffusion of transmitting sunlight, leading to moderate indoor illumination by eliminating extremely bright or dark spots. At the other extreme, such a 3D heterogeneous design with strongly bonded interfaces can enhance the coloration sensitivity of mechanophore-dyed nanocomposites. This work presents insights into the design principles of advanced mechanochromic smart membranes.
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http://dx.doi.org/10.1021/acsnano.1c06403DOI Listing
November 2021

Dopamine Imaging in Living Cells and Retina by Surface-Enhanced Raman Scattering Based on Functionalized Gold Nanoparticles.

Anal Chem 2021 08 20;93(31):10841-10849. Epub 2021 Jul 20.

School of Biomedical Engineering, School of Ophthalmology & Optometry, Wenzhou Medical University, Xueyuan Road 270, Wenzhou 325027, China.

Retinal dopamine is believed to be involved in the development of myopia, which is projected to affect almost half of the world population's visual health by 2050. Direct visualization of dopamine in the retina with high spatial precision is essential for understanding the biochemical mechanism during the development of myopia. However, there are very few approaches for the direct detection of dopamine in the visual system, particularly in the retina. Here, we report surface-enhanced Raman scattering (SERS)-based dopamine imaging in cells and retinal tissues with high spatial precision. The surface of gold nanoparticles is modified with -butylboronic acid-2-mercaptoethylamine and 3,3'-dithiodipropionic acid di(-hydroxysuccinimide ester), which shows excellent specific reaction with dopamine. The existence of dopamine triggers the aggregation of gold nanoparticles that subsequently form plasmonic hot spots to dramatically increase the Raman signal of dopamine. The as-synthesized SERS nanoprobes have been evaluated and applied for dopamine imaging in living cells and retinal tissues in form-deprivation (FD) myopia guinea pigs, followed by further investigation on localized dopamine levels in the FD-treated mice. The results suggest a declined dopamine level in mice retina after 2-week FD treatment, which is associated with the development of myopia. Our approach will greatly contribute to better understanding the localized dopamine level associated with myopia and its possible treatments. Furthermore, the imaging platform can be utilized to sensing other important small molecules within the biological samples.
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http://dx.doi.org/10.1021/acs.analchem.1c01108DOI Listing
August 2021

Anisotropic, Wrinkled, and Crack-Bridging Structure for Ultrasensitive, Highly Selective Multidirectional Strain Sensors.

Nanomicro Lett 2021 May 4;13(1):122. Epub 2021 May 4.

Department of Mechanical and Aerospace Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, People's Republic of China.

Flexible multidirectional strain sensors are crucial to accurately determining the complex strain states involved in emerging sensing applications. Although considerable efforts have been made to construct anisotropic structures for improved selective sensing capabilities, existing anisotropic sensors suffer from a trade-off between high sensitivity and high stretchability with acceptable linearity. Here, an ultrasensitive, highly selective multidirectional sensor is developed by rational design of functionally different anisotropic layers. The bilayer sensor consists of an aligned carbon nanotube (CNT) array assembled on top of a periodically wrinkled and cracked CNT-graphene oxide film. The transversely aligned CNT layer bridge the underlying longitudinal microcracks to effectively discourage their propagation even when highly stretched, leading to superior sensitivity with a gauge factor of 287.6 across a broad linear working range of up to 100% strain. The wrinkles generated through a pre-straining/releasing routine in the direction transverse to CNT alignment is responsible for exceptional selectivity of 6.3, to the benefit of accurate detection of loading directions by the multidirectional sensor. This work proposes a unique approach to leveraging the inherent merits of two cross-influential anisotropic structures to resolve the trade-off among sensitivity, selectivity, and stretchability, demonstrating promising applications in full-range, multi-axis human motion detection for wearable electronics and smart robotics.
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http://dx.doi.org/10.1007/s40820-021-00615-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8096879PMC
May 2021

Ecofriendly Microencapsulated Phase-Change Materials with Hybrid Core Materials for Thermal Energy Storage and Flame Retardancy.

Langmuir 2021 Jun 17;37(21):6380-6387. Epub 2021 May 17.

School of Civil and Environmental Engineering, Nanyang Technological University (NTU), 639798 Singapore.

Microencapsulated phase-change material (ME-PCM) employing octadecane as a core material has been practiced for thermal-energy-storage (TES) applications in buildings. However, octadecane as a hydrocarbon-based PCM is flammable. Herein, silica-shelled microcapsules (SiO-MCs) and poly(urea-formaldehyde)-shelled microcapsules (PUF-MCs) were successfully prepared, loaded with octadecane/tributyl phosphate (TBP) as hybrid core materials, which not only exhibited good TES properties but also high-effective flame retardancy. SiO-MC (Δ = 124.6 J g and Δ = 124.1 J g) showed weaker TES capacity than PUF-MC (Δ = 186.8 J g, Δ = 188.5 J g) but better flame retardancy with a lower peak heat-release rate (HRR) of 460.9 W g (556.9 W g for PUF-MCs). As compared with octadecane (38.7 kJ g), the reduction in total heat release (THR) for SiO-MC was up to 22% (30.1 kJ g) with combustion time shortened by 1/6. SiO-MC had a typical diameter of 150-210 μm, shell thickness of ∼6.5 μm, and a core fraction of 84 wt %. SiO-MC showed better thermal stability with a higher initial evaporation/pyrolysis temperature than PUF-MC. The thermal decomposition of MCs with its mechanism of flame retardancy was significantly studied using thermogravimetric analysis/infrared spectrometry (TG-IR). The strategy presented in this study should inspire the development of microcapsules with PCMs/flame retardants as hybrid core materials for structural applications.
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http://dx.doi.org/10.1021/acs.langmuir.0c03587DOI Listing
June 2021

Solid-State Thermal Memory of Temperature-Responsive Polymer Induced by Hydrogen Bonds.

Nano Lett 2021 May 21;21(9):3843-3848. Epub 2021 Apr 21.

CAS Key Laboratory of Mechanical Behavior and Design of Materials, University of Science and Technology of China, Hefei 230026, P. R. China.

Memory is an essential element for a computer to process information, which is integrated by logical circuits. Like electronic computing, thermal information can also be stored and read out by a thermal memory. Here, we show that a phase-changing polymer with hysteretic thermal transport properties can be experimentally processed into thermal memories at room temperature. We used a temperature-responsive and reversible polymer synthesized with melamine (M) and 6,7-dimethoxy-2,4[1H,3H]-quinazolinedione (Q) as a model system to demonstrate the manipulation of thermal transport at a molecular level. Fourier transform infrared spectroscopy and differential scanning calorimetry measurements indicate that this hysteretic behavior is based on the interaction of hydrogen bonds at high (317 K) and low (297 K) temperatures. This work demonstrates a controllable phonon transport process through the manipulation of hydrogen bonds, and thus it has potential applications in thermal memories.
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http://dx.doi.org/10.1021/acs.nanolett.1c00289DOI Listing
May 2021

Author Correction: A role of color vision in emmetropization in C57BL/6J mice.

Sci Rep 2021 Apr 14;11(1):8556. Epub 2021 Apr 14.

School of Ophthalmology and Optometry and Eye Hospital, Wenzhou Medical University, 270 Xueyuan Road, Wenzhou, 325027, Zhejiang, China.

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http://dx.doi.org/10.1038/s41598-021-88185-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8046967PMC
April 2021

Robust Microcapsules with Durable Superhydrophobicity and Superoleophilicity for Efficient Oil-Water Separation.

ACS Appl Mater Interfaces 2020 Dec 10;12(51):57547-57559. Epub 2020 Dec 10.

Department of Mechanical and Aerospace Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong SAR, China.

The poor ultraviolet (UV) resistance and insufficient solvent compatibility are challenges for long-term storage and service of oil-water separation materials in practical applications. Herein, a superhydrophobic/superoleophilic surface with nano- to microscale hierarchical structures was formed spontaneously on robust microcapsules (MCs) via in situ polymerization and a sol-gel surface treatment. The resultant MCs possessed superior UV-resistant and solvent-proof superhydrophobicity. The water contact angles (WCAs) of the MC coating remained above 160° and the sliding angles (SAs) were below 3° after 9 days of UV aging test or 20 days of nonpolar and polar aprotic solvent immersion tests. More interestingly, these MCs can be used to separate the oil phase from its aqueous emulsion effectively, achieving a high and reusable separation efficiency with over 90% oil purity after 10 cycles of filtrations even after 13 days of UV aging. Therefore, these novel MCs will exhibit effective oil-water separation performance, superior chemical stability, outstanding reusability, and long-term storage stability for promising practical applications.
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http://dx.doi.org/10.1021/acsami.0c15455DOI Listing
December 2020

A role of color vision in emmetropization in C57BL/6J mice.

Sci Rep 2020 09 10;10(1):14895. Epub 2020 Sep 10.

School of Ophthalmology and Optometry and Eye Hospital, Wenzhou Medical University, 270 Xueyuan Road, Wenzhou, 325027, Zhejiang, China.

Spectral composition affects emmetropization in both humans and animal models. Because color vision interacts the effects of chromatic defocus, we developed a method to bypass the effects of longitudinal chromatic aberration by placing a spectral filter behind the optics of the eye, using genetic tools. Newborn C57BL/6J (B6) mice were reared in quasi-monochromatic red (410-510 nm) or blue (585-660 nm) light beginning before eye-opening. Refractive states and ocular dimensions were compared at 4, 6, 8, and 10 weeks with mice reared in normal white light. Cre recombinase-dependent Ai9 reporter mice were crossed with Chx10-Cre to obtain Chx10-Cre;Ai9 mice, expressing red fluorescent protein in retinal Cre-positive cells. Ai9 offsprings, with and without Cre, were reared under a normal visual environment. Refraction and axial components were measured as described above. Expression levels of M and S opsin were quantified by western blotting at 10 weeks. Compared with those reared in white light, B6 mice reared in red light developed relative hyperopia, principally characterized by flattening of corneal curvature. Emmetropization was not affected by blue light, possibly because the reduction in vitreous chamber depth compensated for the increase in corneal curvature. Compared with Cre-negative littermates, the refraction and axial dimensions of Chx10-Cre;Ai9 mice were not significantly different at the follow-up timepoints. M opsin levels were higher in Chx10-Cre;Ai9 mice at 10 weeks while S opsin levels were not different. Red light induced a hyperopic shift in mouse refractive development. Emmetropization was not impacted in mice with perturbed color vision caused by intrinsic red-fluorescent protein, suggesting that color vision may not be necessary in mouse emmetropization when other mechanisms are present.
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http://dx.doi.org/10.1038/s41598-020-71806-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7483713PMC
September 2020

Reversible visible/near-infrared light responsive thin films based on indium tin oxide nanocrystals and polymer.

Sci Rep 2020 Jul 30;10(1):12808. Epub 2020 Jul 30.

Department of Mechanical and Aerospace Engineering, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, 999077, China.

In this study, we design a novel thermo- and photo-responsive nanocomposite film prepared by depositing indium tin oxide nanocrystals via the coating of amphiphilic copolymer on polycaprolactone substrates (INCP). The INCP film shows reversible surface morphology change properties by changing temperature as well as turning ON/OFF NIR laser. Especially, as the temperature changes from 25 to 75 °C, the film could regulate light transmittance from 75 to 90% across the visible and near-infrared region (500-1,750 nm). In addition, the film also exhibits excellent recycle and thermal stability at different temperature. Our results reveal that reversible surface morphology change properties are caused by curvature adjustment of film, which is owing to the coupling effect between copolymer and PCL with different thermal expansion strains. Our results suggest a possible strategy for the preparation of smart responsive materials in the future, which provides a reference for the development of new energy-saving materials.
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http://dx.doi.org/10.1038/s41598-020-69110-yDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7393154PMC
July 2020

Mechanochromic Fluorescent Polymers Enabled by AIE Processes.

Macromol Rapid Commun 2021 Jan 10;42(1):e2000311. Epub 2020 Jul 10.

Center for AIE Research, College of Materials Science and Engineering, Shenzhen University, Shenzhen, 518060, China.

Polymeric materials are susceptible to the chain re-conformation, reorientation, slippage, and bond cleavage upon mechanical stimuli, which are likely to further grow into macro-damages and eventually lead to the compromise or loss of materials performance. Therefore, it is of great academic importance and practical significance to sensitively detect the local mechanical states in polymers and monitor the dynamic variations in polymer structures and properties under external forces. Mechanochromic fluorescent polymers (MFP) are a class of smart materials by utilizing sensitive fluorescent motifs to detect polymer chain events upon mechanical stimuli. Taking advantage of the unique aggregation-induced emission (AIE) effect, a variety of MFP systems that can self-report their mechanical states and mechano-induced structural and property changes through fluorescence signals have been developed. In this feature article, an overview of the recent progress on MFP systems enabled by AIE process is presented. The main design principles, including physically doping dispersed or microencapsulated AIE luminogens (AIEgens) into polymer matrix, chemically linking AIEgens in polymer backbones, and utilizing the clusterization-triggered emission of polymers containing nonconventional luminogens, are discussed with representative examples. Perspectives on the existing challenges and problems in this field are also discussed to guide future development.
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http://dx.doi.org/10.1002/marc.202000311DOI Listing
January 2021

Te Nanoneedles Induced Entanglement and Thermoelectric Improvement of SnSe.

Materials (Basel) 2020 Jun 1;13(11). Epub 2020 Jun 1.

School of Chemical Engineering & Materials Science, Chung-Ang University, Seoul 06974, Korea.

Chalcogenide-based materials have attracted widespread interest in high-performance thermoelectric research fields. A strategy for the application of two types of chalcogenide for improved thermoelectric performance is described herein. Tin selenide (SnSe) is used as a base material, and Te nanoneedles are crystallized in the SnSe, resulting in the generation of a composite structure of SnSe with Te nanoneedles. The thermoelectric properties with various reaction times are investigated to reveal the optimum conditions for enhanced thermoelectric performance. A reaction time of 4 h at 450 K generated a composite Te nanoneedles/SnSe sample with the maximum value, 3.2 times larger than that of the pristine SnSe. This result is attributed to both the reduced thermal conductivity from the effective phonon scattering of heterointerfaces and the improved electrical conductivity value due to the introduction of Te nanoparticles. This strategy suggests an approach to generating high-performance practical thermoelectric materials.
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http://dx.doi.org/10.3390/ma13112523DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7321485PMC
June 2020

MITF protects against oxidative damage-induced retinal degeneration by regulating the NRF2 pathway in the retinal pigment epithelium.

Redox Biol 2020 07 16;34:101537. Epub 2020 Apr 16.

Laboratory of Developmental Cell Biology and Disease, School of Ophthalmology and Optometry and Eye Hospital, Wenzhou Medical University, China; State Key Laboratory Cultivation Base and Key Laboratory of Vision Science of Ministry of Health and Zhejiang Provincial Key Laboratory of Ophthalmology, Wenzhou Medical University, Wenzhou, 325003, China.

Oxidative damage is one of the major contributors to retinal degenerative diseases such as age-related macular degeneration (AMD), while RPE mediated antioxidant defense plays an important role in preventing retinopathies. However, the regulatory mechanisms of antioxidant signaling in RPE cells are poorly understood. Here we show that transcription factor MITF regulates the antioxidant response in RPE cells, protecting the neural retina from oxidative damage. In the oxidative stress-induced retinal degeneration mouse model, retinal degeneration in Mitf+/- mice is significantly aggravated compared to WT mice. In contrast, overexpression of Mitf in Dct-Mitf transgenic mice and AAV mediated overexpression in RPE cells protect the neural retina against oxidative damage. Mechanistically, MITF both directly regulates the transcription of NRF2, a master regulator of antioxidant signaling, and promotes its nuclear translocation. Furthermore, specific overexpression of NRF2 in Mitf+/- RPE cells activates antioxidant signaling and partially protects the retina from oxidative damage. Taken together, our findings demonstrate the regulation of NRF2 by MITF in RPE cells and provide new insights into potential therapeutic approaches for prevention of oxidative damage diseases.
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http://dx.doi.org/10.1016/j.redox.2020.101537DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7191850PMC
July 2020

KIT ligand protects against both light-induced and genetic photoreceptor degeneration.

Elife 2020 04 3;9. Epub 2020 Apr 3.

Laboratory of Developmental Cell Biology and Disease, School of Ophthalmology and Optometry and Eye Hospital, Wenzhou Medical University, Wenzhou, China.

Photoreceptor degeneration is a major cause of blindness and a considerable health burden during aging but effective therapeutic or preventive strategies have not so far become readily available. Here, we show in mouse models that signaling through the tyrosine kinase receptor KIT protects photoreceptor cells against both light-induced and inherited retinal degeneration. Upon light damage, photoreceptor cells upregulate Kit ligand (KITL) and activate KIT signaling, which in turn induces nuclear accumulation of the transcription factor NRF2 and stimulates the expression of the antioxidant gene . Conversely, a viable mutation promotes light-induced photoreceptor damage, which is reversed by experimental expression of . Furthermore, overexpression of KITL from a viral AAV8 vector prevents photoreceptor cell death and partially restores retinal function after light damage or in genetic model of human retinitis pigmentosa. Hence, application of KITL may provide a novel therapeutic avenue for prevention or treatment of retinal degenerative diseases.
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http://dx.doi.org/10.7554/eLife.51698DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7170656PMC
April 2020

A Facile Strategy To Prepare Smart Coatings with Autonomous Self-Healing and Self-Reporting Functions.

ACS Appl Mater Interfaces 2020 Jan 14;12(4):4870-4877. Epub 2020 Jan 14.

Center for AIE Research, College of Materials Science and Engineering , Shenzhen University , Shenzhen 518060 , China.

Herein, we report a smart coating with autonomous self-healing and self-reporting functions by simple integration of one-component microcapsules into the matrix without external intervention. The microcapsules containing hexamethylene diisocyanate (HDI) solution of aggregation-induced emission luminogens (AIEgens) were synthesized, and their properties, such as their composition, thermal stability, morphology, and damage-indicating ability, were investigated systematically. The AIEgen/HDI microcapsule-embedded coatings display adaptive self-repair of scratches and simultaneous high-contrast indication of the healed damage. Two commercialized AIEgens, tetraphenylethylene (TPE) and its derivative with dimethoxyl and benzylidene-methyloxazolone moieties (DM-TPE-BMO), were utilized as examples to demonstrate the feasibility of this concept in diverse polymer matrixes (including blue autofluorescent matrixes). It was found that the content of AIEgens can even be lowered to 0.05 wt %. This facile, economical, and feasible strategy toward the dual functions of self-repairing and self-sensing provides a new route for enhancing the longevity and reliability of polymer coatings, which is appealing and of great importance in practical applications.
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http://dx.doi.org/10.1021/acsami.9b18919DOI Listing
January 2020

Effect of Thiodiphenol-Based Epoxy Resin on the Thermal Properties of an Aluminum Oxide Composite.

J Nanosci Nanotechnol 2020 Jan;20(1):603-607

School of Chemical Engineering & Material Science, Chung-Ang University, Heukseok-Dong, Dongjak-Gu, Seoul, 156-756, Korea.

The effects of thiodiphenol based epoxy resin on the thermal property of the composites containing aluminum oxide were investigated. The thermal conductivities and thermal diffusivities of the composites were dependent on the polymer resin. At the same content of Al₂O₃, the thermal conductivity and thermal diffusivity of composites made by synthesized polymer resin exhibited higher than that of composite made by bisphenol-A resin. The obtained maximum thermal conductivity of the composite was 0.25 W/mK, which was 0.4 times as large as that of the conventional bisphenol-A epoxy resin which has an amorphous structure. It is supposed that the reason for the high heat conductivity obtained in thiodiphenol based epoxy resin is certain high packing structure.
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http://dx.doi.org/10.1166/jnn.2020.17262DOI Listing
January 2020

A Study on the Thermal Conductivity of Poly(lactic acid)/Alumina Composites: The Effect of the Filler Treatment.

J Nanosci Nanotechnol 2020 01;20(1):229-238

School of Chemical Engineering & Materials Science, Chung-Ang University, Seoul 156-756, Republic of Korea.

The excessive utilization of petroleum-based products has given rise to environmental concerns that have led to the shift in the research interest toward recyclable and biodegradable products. Polylactic acid (PLA), an aliphatic polyester that can be obtained from renewable sources, is used in a wide range of applications in different industrial sectors. This study demonstrates the change in the thermal conductivity of 30% alumina filled PLA after a hydrophobic surface modification was applied to the filler. Fourier transmission infrared and X-ray photoelectric spectroscopy results confirmed the successful modification of the alumina particles surfaces. The improvement in the interaction between the modified alumina and PLA matrix was revealed by examining the morphology micrograph obtained by field emission scanning electron microscopy. Since alumina is a highly thermally conductive material, the enhancement in the interfacial adhesion between the filler and matrix leads to an increase of 120% in the thermal conductivity of the PLA/Alumina composite compared to that of the neat PLA. In addition, the PLA/Alumina composite showed an increase in the storage modulus due to the high stiffness of alumina.
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http://dx.doi.org/10.1166/jnn.2020.17260DOI Listing
January 2020

Robust Metallic Microcapsules: A Direct Path to New Multifunctional Materials.

ACS Appl Mater Interfaces 2019 Mar 20;11(9):9621-9628. Epub 2019 Feb 20.

Department of Mechanical and Aerospace Engineering , The Hong Kong University of Science and Technology , Kowloon 999077 , Hong Kong SAR.

Robustness of microcapsule shells determined the service life and application areas of final smart materials including self-healing composites, anticorrosion coatings, smart concretes, and so on. Herein, we designed and synthesized metal microcapsules by conducting electroless plating directly on liquid droplet surfaces, and metal shells showed superior stability in thermal (600 °C) and polar solvents (acetone and N,N-dimethylformamide) environments. More interestingly, the mechanical strength of metal shells was ten times higher than those of all published microcapsules. Besides, the smart epoxy composites remained stable mechanical properties with metal microcapsule concentrations, and this is the first time to report such results. For engineering materials, mechanical properties played an important role in practical applications, and a higher strength usually accompanied with better safety and longer service life. The microcapsules with designable structures could be synthesized by adjusting shell thickness and core fractions for practical requirements. The metal microcapsules had great potentials to be applied in a smart metallic matrix, conductive multifunctional materials, and pH-responsive materials. In addition, the electroless plating technique was also first applied to liquid surfaces pushing the development of novel smart materials.
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http://dx.doi.org/10.1021/acsami.9b00827DOI Listing
March 2019

Fabrication of Water Soluble Polymer Capsules for Protecting Mineral Admixtures in Groundwater for Emergency Recovery of Sinkhole.

J Nanosci Nanotechnol 2019 03;19(3):1649-1656

Department of Chemical Engineering, CHUNG-ANG University, Dongjak, Seoul, 06974, Republic of Korea.

Polyethylene glycol (PEG) based water-soluble polymer composites were fabricated for mineral admixture encapsulants to be used in underground sinkhole restoration. Linear low-density polyethylene (LLDPE) and talc were added to the composites to increase their mechanical strengths and heat resistances. PEG/LLDPE/Talc composites were manufactured via melt mixing using a twin extruder. Blending PEG and LLDPE increased the mechanical properties and heat resistances of the composite, but decreased the water solubility. Talc was added to the composite to increase mechanical properties and heat resistance. The addition of talc increased the water solubilities of PEG-based composites. The highest tensile strength and impact strength were 2.89 MPa and 2.86, respectively, the increase rate being 9.63-fold relative to that of pristine PEG.
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http://dx.doi.org/10.1166/jnn.2019.16196DOI Listing
March 2019

Effect of Surface Modifications and Their Reaction Conditions on Multi-Walled Carbon Nanotubes for Thermal Conductive Composite Material.

J Nanosci Nanotechnol 2019 Mar;19(3):1525-1532

School of Chemical Engineering and Materials Science, Chung-Ang University, Seoul 06974, Republic of Korea.

Thermally conductive composite materials were fabricated using Al₂O₃ and surface-modified MWCNTs on an ETDS matrix. The MWCNT surfaces were modified using a solution containing H2O₂ and H₂SO₄/HNO₃ and examined at various reaction times. After surface modification, the ratios of the functional groups introduced were compared. The changes in MWCNT morphology and thermal conductivity were also investigated for various reaction times. It was observed from the results that the MWCNTs exposed to 1 h acid treatment had the highest thermal conductivity without any decrease in their length. Based on the optimum oxidization of MWCNTs, further surface modification was performed using APTES, a silane coupling agent, using two different reactions. After the reaction, large particle aggregations were observed on the amine-terminated MWCNTs, which reacted with a mixture of EtOH and DI water. These agglomerates did not re-disperse after long-time sonication. However, the silanol-terminated MWCNTs were easily dispersed in EtOH via sonication, and their composite materials had outstanding thermal conductivities. Moreover, more amount of MWCNTs were processable using the same Al₂O₃ and ETDS concentrations, which also led to enhanced thermal conductivities compared to the other surface modification methods.
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http://dx.doi.org/10.1166/jnn.2019.16194DOI Listing
March 2019

Optimal Co(OH)₂ Nanowire Contents in Graphene Nanosheet Electrode on Its Electrochemical Performance of Supercapacitor.

J Nanosci Nanotechnol 2019 Mar;19(3):1350-1359

School of Chemical Engineering and Materials Science, Chung-Ang University, Seoul 156-756, Republic of Korea.

Graphene/Co(OH)₂ nanowire composite films were successfully synthesized using a simple three-step treatment, and the effect of the Co(OH)₂ nanowire content on the electrochemical properties of the composite films was studied in this study. One-dimensional Co(OH)₂ nanowires were homogeneously embedded and dispersed between the prepared graphene papers, forming a layered graphene/Co(OH)₂ nanowire hybrid structure. These composite films exhibited better electrochemical properties than the previously reported graphene composites with carbon spheres such as graphene/CNT composites. These graphene composites were fabricated using the same method we used in this study but without the addition of Co(OH)₂ nanowires. The addition of a small amount of Co(OH)₂ to reduced graphene oxide (rGO) (RGO:Co(OH)₂=5:1) yielded thick paper-like rGO/Co(OH)₂ sandwiches, which showed an excellent specific capacitance of 1032.57 Fg at a scan rate of 5 mVs. These results indicate the potential of these composites for the development of highly capacitive energy storage devices for practical applications.
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http://dx.doi.org/10.1166/jnn.2019.16195DOI Listing
March 2019

Dopamine Receptor Subtypes Mediate Opposing Effects on Form Deprivation Myopia in Pigmented Guinea Pigs.

Invest Ophthalmol Vis Sci 2018 09;59(11):4441-4448

School of Ophthalmology and Optometry and Eye Hospital, Wenzhou Medical University, Wenzhou, Zhejiang, China.

Purpose: We reported previously that changes in dopamine receptor (DR) subtype activation modulate spontaneous myopia progression in albino guinea pigs. To determine if DR control of refractive error development is different than in its normal counterpart, we evaluated the contribution of dopaminergic pathways to emmetropization and form deprivation myopia (FDM) progression in pigmented guinea pigs.

Methods: Monocular myopia was induced by unilateral form-deprivation (FD). The effects of agonists of D1R (SKF38393) and D2R (quinpirole), the corresponding antagonists (SCH23390 and sulpiride), and vehicle were tested by peribulbar injection around FD or untreated control eyes. High-performance liquid chromatography with electrochemical detection quantified retinal and vitreous dopamine (DA) and 4-dihydroxyphenylacetic acid (DOPAC) levels. Ocular refraction and axial dimensions were measured using eccentric infrared photoretinoscopy (EIR) and A-scan ultrasonography, respectively, initially and after 2 or 4 weeks of treatment.

Results: After treatment with any of these four agents for 2 weeks, retinal and vitreal DA and DOPAC levels were not significantly different in drug- and vehicle-treated eyes. Neither agonism nor antagonism of D1R or D2R activity affected emmetropization. In contrast, D1R activation by SKF38393 inhibited FDM progression, while D2R activation by quinpirole augmented this response. On the other hand, D2R antagonism with sulpiride slowed FDM progression while D1R antagonism with SCH23390 had no effect.

Conclusions: In pigmented guinea pigs, D1R activation inhibited, whereas D2R activation enhanced, FDM. These results closely mirror previous findings in albino animals and offer further evidence that DA and its cognate receptors affect refractive error regulation in guinea pigs.
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http://dx.doi.org/10.1167/iovs.17-21574DOI Listing
September 2018

Flexible electrochromic materials based on CNT/PDA hybrids.

Adv Colloid Interface Sci 2018 Aug 24;258:21-35. Epub 2018 Jul 24.

Department of Mechanical Engineering, Khalifa University, P.O. Box: 127788, Abu Dhabi, United Arab Emirates. Electronic address:

Materials that change color in response to external stimuli can cater to diverse applications from sensing to art. If made flexible, stretchable and weavable, they may even be directly integrated with advanced technologies such as smart textiles. A new class of engineered composite based on polydiacetylene (PDA) functionalized carbon nanotubes (CNT) shows tremendous potential in this regard. While the inherent multi stimuli chromatic response of the polymer (blue to red) is retained, the underlying conducting CNTs invoke electrochromism in PDA. Further, the fiber form factor of dry-spun CNT yarns facilitate direct weaving of large scale electrochromic fabrics, where current flow and thus color change can be accurately controlled. This review summarizes the fundamental aspects of CNT yarns and PDAs, focusing especially on their interaction chemistry which results in the scientifically and commercially appealing electrochromic transition in these hybrids.
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http://dx.doi.org/10.1016/j.cis.2018.07.003DOI Listing
August 2018

Cause and Effect Relationship between Changes in Scleral Matrix Metallopeptidase-2 Expression and Myopia Development in Mice.

Am J Pathol 2018 08 25;188(8):1754-1767. Epub 2018 May 25.

School of Optometry and Ophthalmology and Eye Hospital, Wenzhou Medical University, Wenzhou, Zhejiang, People's Republic of China; State Key Laboratory of Optometry, Ophthalmology, and Vision Science, P. R. China and Zhejiang Provincial Key Laboratory of Ophthalmology and Optometry, Wenzhou, Zhejiang, People's Republic of China. Electronic address:

Myopia is a serious sight-compromising condition in which decreases in scleral biomechanical strength are associated with protease up-regulation resulting in thinning of its collagenous framework and changes in the extracellular matrix composition. Matrix metallopeptidase (MMP)-2 is one of the known proteases mediating these alterations. To determine whether MMP-2 up-regulation precedes myopia development, the direct effects of gain and loss in Mmp2 gene function were evaluated on refractive development and form deprivation myopia in mice. Four weeks after injecting an adeno-associated virus serotype 8 packaged Mmp2 overexpression vector (AAV8-Mmp2), scleral MMP-2 up-regulation was accompanied by significant myopia in a normal visual environment. In contrast, AAV8 packaging with shRNA targeting Mmp2 inhibited rises in MMP-2 expression induced by form deprivation by 54% and reduced myopia development by 23% compared with eyes injected with an irrelevant scrambled sequence. Because opposing changes in MMP-2 protein expression levels had corresponding effects on myopia progression, up-regulation of this protease contributes to inducing this condition. This notion of a cause-and-effect relationship between MMP-2 up-regulation and myopia development is supported by showing that form-deprived myopia development was attenuated by 27% in fibroblast-specific Mmp2 deletion (S100a4Mmp2) mice relative to Cre-negative littermates (Mmp2). Therefore, MMP-2 is a potential drug target for inhibiting myopia progression.
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http://dx.doi.org/10.1016/j.ajpath.2018.04.011DOI Listing
August 2018

Fabrication and Release Behavior of Microcapsules with Double-Layered Shell Containing Clove Oil for Antibacterial Applications.

ACS Appl Mater Interfaces 2018 May 27;10(18):15532-15541. Epub 2018 Apr 27.

Department of Mechanical and Aerospace Engineering , The Hong Kong University of Science and Technology , Clear Water Bay , Kowloon , Hong Kong SAR , China.

In this study, double-layer polyurethane/poly(urea-formaldehyde) (PU/PUF) shell microcapsules containing clove oil with antibacterial properties were successfully synthesized via in situ and interfacial polymerization reactions in an oil-in-water emulsion. The morphology, core-shell structure, and composition of the microcapsules were investigated systematically. Additionally, the release behaviors of microcapsules synthesized under different reaction parameters were studied. It was found that the release rate of clove oil can be controlled by tuning the amount of PU reactants and the length of PUF deposition time. The release profile fitted well against the Baker-Lonsdale model, which indicates diffusion as the primary release mechanism. Experimental results based on the ASTM E2315 time kill test revealed that the fabricated microcapsules have great antibacterial activities against the marine bacteria Vibrio coralliilyticus, Escherichia coli, Exiguobacterium aestuarii, and marine biofilm-forming bacteria isolated from the on-site contaminated samples, showing their great potential as an eco-friendly solution to replace existing toxic antifouling agent.
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http://dx.doi.org/10.1021/acsami.8b05467DOI Listing
May 2018

Prostaglandin F2α Receptor Modulation Affects Eye Development in Guinea Pigs.

Basic Clin Pharmacol Toxicol 2018 Sep 29;123(3):263-270. Epub 2018 May 29.

School of Ophthalmology and Optometry and Eye Hospital, Wenzhou Medical University, Wenzhou, Zhejiang, China.

Retinal arachidonic acid (ARA) levels in form-deprived eyes decline in guinea pigs. As prostaglandin F2α (PGF2α) is an ARA metabolite and endogenous agonist of prostaglandin F receptor (FP), we have been suggested that down-regulation of PGF2α-FP receptor signalling pathway contributes to myopia onset. To test this hypothesis, this study determines whether: (i) retinal PGF2α levels decline during the development of form deprivation myopia (FDM) in guinea pigs; (ii) FP receptor agonism and antagonism alter emmetropization and myopia development. Pigmented guinea pigs were randomly assigned to normal vision and form-deprived groups. Ultraperformance liquid chromatography coupled with a mass spectrometer (UPLC-MS) measured retinal PGF2α levels 2 weeks after form deprivation (FD). The selective FP agonist, latanoprost acid (LAT) and its corresponding antagonist, AL8810, were peribulbarly injected into each group. An eccentric infrared photorefractor (EIR) monitored refraction. A-scan ultrasonography measured axial elongation (AL) and vitreous chamber depth (VCD). Tonometry measured the intraocular pressure (IOP). Retinal PGF2α levels declined in form-deprived eyes compared to those in normal eyes. Neither LAT nor AL8810 affected IOP with or without FD. On the other hand, after 4 weeks of daily 0.5 μg AL8810 treatment, a myopia of -1.99 ± 0.34 dioptre (D) developed, but LAT had no effect on emmetropization in a normal visual environment. Nevertheless, daily 30 μg LAT treatment for 4 weeks inhibited FDM development by 41% (vehicle control: -8.39 ± 0.45 D; LAT: -4.95 ± 0.39 D; two-way anova with repeated measures, p < 0.05). Down-regulation of PGF2α-FP receptor signalling pathway may contribute to myopia onset as retinal PGF2α declined in myopic eyes and antagonism of FP receptor by AL8810 induced a myopic shift in normal vision environment. Meanwhile, up-regulation of this pathway by LAT inhibited FDM development. However, the mechanism underlying LAT-induced FDM inhibition needs further clarification. This uncertainty exists because its inhibition of FDM suggests that LAT strengthens the scleral framework which reduces axial elongation. On the other hand, its IOP-lowering effect is attributed to thinning and weakening the scleral framework in glaucoma treatment.
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http://dx.doi.org/10.1111/bcpt.13017DOI Listing
September 2018

Hollow glass bubbles etched with tunable sizes of through-holes.

J Microencapsul 2018 Mar 26;35(2):192-203. Epub 2018 Mar 26.

c Department of Mechanical and Aerospace Engineering , Hong Kong University of Science and Technology , Kowloon , China.

Hollow glass bubbles (HGBs) with through-holes at micron level were fabricated by etching them using diluted 1% hydrofluoric acid (HF) solution in a specially designed reaction system. In this study, the function of each component in the system was carefully investigated and improved to realise the controllable etching process. Various parameters were investigated to explore the optimal etching condition. Highest gross yield of about 85% and effective yield of about 50% were obtained at the optimised etching condition. A separating method was proposed to separate the etched HGBs with different hole sizes with the help of reduced pressure. After separation, HGBs with hole size at sub-micron level, less than 10 µm, and bigger than 10 µm, were achieved. The well-etched HGBs can be used as universal containers to store both reactive and inactive chemicals for applications in self-healing materials, biochemical engineering, and energy industry.
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http://dx.doi.org/10.1080/02652048.2018.1452992DOI Listing
March 2018

Graphene Size-Dependent Multifunctional Properties of Unidirectional Graphene Aerogel/Epoxy Nanocomposites.

ACS Appl Mater Interfaces 2018 Feb 9;10(7):6580-6592. Epub 2018 Feb 9.

Integrative Research Center for Two-Dimensional Functional Materials, Institute of Interdisciplinary Convergence Research, Chung-Ang University , Seoul 06974, Republic of Korea.

Unidirectional graphene aerogels (UGAs) with tunable densities, degrees of alignment, and electrical conductivities are prepared by varying the average size of precursor graphene oxide (GO) sheets between 1.1 and 1596 μm. UGAs prepared using ultralarge GO (UL-UGA) outperform those made from small GO in these properties. The UL-UGA/epoxy composites prepared by infiltrating liquid epoxy resin into the porous UGA structure exhibit an excellent electrical conductivity of 0.135 S/cm, along with an ultralow percolation threshold of 0.0066 vol %, which is one of the lowest values ever reported for all graphene-based composites. Owing to their three-dimensional interconnected network, a high degree of alignment, and effective reduction, UL-UGAs effectively enhance the fracture toughness of epoxy by 69% at 0.11 vol % graphene content through unique toughening mechanisms, such as crack pinning, crack deflection, interfacial debonding, and graphene rupture. These aerogels and composites can be mass-produced thanks to the facile, scalable, and cost-efficient fabrication process, which will find various multifunctional applications.
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http://dx.doi.org/10.1021/acsami.7b19069DOI Listing
February 2018

Modification of the contact surfaces for improving the puncture resistance of laminar structures.

Sci Rep 2017 07 26;7(1):6615. Epub 2017 Jul 26.

CAS Key Laboratory of Mechanical Behavior and Design of Materials, Department of Modern Mechanics, University of Science and Technology of China, Hefei, 230027, China.

Uncovering energy absorption and surface effects of various penetrating velocities on laminar structures is essential for designing protective structures. In this study, both quasi-static and dynamic penetration tests were systematical conducted on the front surfaces of metal sheets coated with a graphene oxide (GO) solution and other media. The addition of a GO fluid film to the front impact surface aided in increasing the penetration strength, improving the failure extension and dissipating additional energy under a wide-range of indentation velocity, from 3.33 × 10 m/s to 4.42 m/s. The coated -surfaces improved the specific energy dissipation by approximately 15~40% relative to the dry-contact configuration for both single-layer and double-layer configurations, and specific energy dissipations of double-layer configurations were 20~30% higher than those of the single-layer configurations. This treatment provides a facile strategy in changing the contact state for improving the failure load and dissipate additional energy.
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http://dx.doi.org/10.1038/s41598-017-06007-3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5529432PMC
July 2017

Changes in retinal metabolic profiles associated with form deprivation myopia development in guinea pigs.

Sci Rep 2017 06 5;7(1):2777. Epub 2017 Jun 5.

School of Ophthalmology and Optometry and Eye Hospital, Wenzhou Medical University, Wenzhou, Zhejiang, China.

Retinal metabolic changes have been suggested to be associated with myopia development. However, little is known about either their identity or time dependent behavior during this sight compromising process. To address these questions, gas chromatography time-of-flight mass spectrometry (GC-TOF/MS) was applied to compare guinea pig retinal metabolite levels in form deprivation (FD) eyes at 3 days and 2 weeks post FD with normal control (NC) eyes. Orthogonal partial least squares (OPLS) models discriminated between time dependent retinal metabolic profiles in the presence and absence of FD. Myopia severity was associated with more metabolic pattern differences in the FD than in the NC eyes. After 3 days of FD, 11 metabolite levels changed and after 2 weeks the number of differences increased to 16. Five metabolites continuously decreased during two weeks of FD. Two-way ANOVA of the changes identified by OPLS indicates that 15 out of the 22 metabolites differences were significant. Taken together, these results suggest that myopia progression is associated with an inverse relationship between increases in glucose accumulation and lipid level decreases in form-deprived guinea pig eyes. Such changes indicate that metabolomic studies are an informative approach to identify time dependent retinal metabolic alterations associated with this disease.
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http://dx.doi.org/10.1038/s41598-017-03075-3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5459838PMC
June 2017

Superlong Salicylideneaniline Semiconductor Nanobelts Prepared by a Magnetic Nanoparticle-Assisted Self-Assembly Process for Luminescence Thermochromism.

ACS Omega 2017 May 24;2(5):2264-2272. Epub 2017 May 24.

Department of Mechanical and Aerospace Engineering, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong 999077, China.

Controlling the molecular assembling and nanomorphology of organic semiconductors is crucial to obtain high-performance electronic devices. In this work, we have first reported novel superlong salicylideneaniline nanobelts (mHBA) using the magnetic nanoparticle-assisted self-assembly process. Our results show that magnetic nanoparticles will obviously influence the self-assembly behavior, nanomorphology, and crystal structure of molecular HBA. Moreover, the intensity of fluorescence mHBA exhibits decreasing and increasing patterns, with the increase in temperature over a wide temperature range of 8 to 295 K. To elucidate the origin of tautomer forms, the ground and excited states of mHBA were experimentally and theoretically studied. Our results suggest that superlong HBA nanobelts provide a promising intelligent fluorescent thermometer and an organic field-effect transistor.
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http://dx.doi.org/10.1021/acsomega.7b00219DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6641110PMC
May 2017
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