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1.
J Med Internet Res ; 2020 May 14.
Artigo em Inglês | MEDLINE | ID: mdl-32412416

RESUMO

BACKGROUND: In early 2020, the 2019 coronavirus disease (COVID-19) emerged and resulted in community and nosocomial transmissions. Effective contact tracing for potentially exposed healthcare workers (HCWs) is crucial for the prevention and control of infectious disease outbreaks in the healthcare setting. OBJECTIVE: This study aimed to evaluate the comparative effectiveness of contact tracing through real-time locating systems (RTLS) and electronic medical records (EMRs) review at the designated hospital for COVID-19 response in Singapore, during the COVID-19 pandemic. METHODS: Over a two-day study period, all admitted COVID-19 patients, their ward locations, and the HCWs rostered to each ward, were identified to determine the total number of potential contacts between COVID-19 patients and HCWs. The number of staff-patient contacts determined by EMR reviews, RTLS-based contact tracing, and a combination of both methods were evaluated. The use of EMR and RTLS-based contact tracing methods were further validated by comparing their sensitivity and specificity against self-reported staff-patient contacts by HCWs. RESULTS: Of 796 potential staff-patient contacts (between 17 patients and 162 staff), 104(13.1%) were identified on both RTLS and EMR, 54(6.8%) by RTLS alone, 99(12.4%) by EMR alone, and 539(67.7%) not identified through either method. Compared to self-reported contacts, EMR reviews had a sensitivity of 47.2% and specificity of 77.9%, while RTLS had a sensitivity of 72.2% and specificity of 87.7%. The highest sensitivity was obtained by including all contacts identified by either RTLS or EMR (sensitivity 77.8%, specificity 73.4%). CONCLUSIONS: RTLS-based contact tracing had higher sensitivity and specificity than EMR reviews. An integration of both methods provided the best performance for rapid contact tracing, although technical adjustments to the RTLS and increasing user compliance with wearing RTLS tags consistently remain necessary.

2.
Artigo em Inglês | MEDLINE | ID: mdl-32368822

RESUMO

Superwetting membranes with responsive property have attracted heightened attention because of their fine-tunable surface wettability. However, their functional diversity is severely limited by the "black-or-white" wettability transition. Here, we develop a coating strategy to fabricate the multifunctional responsive superwetting membranes with SiO2/octadecylamine patterns. The adjustable patterns relating to the responsive region are the key factor for functional diversity. Specifically, the coated part of the membrane displays superhydrophobicity/superhydrophilicity transition under different pH values, while the uncoated part exhibits invariant superhydrophilicity, thereby endowing the membranes with anisotropic/isotropic wettability transition property. Based on the innovative anisotropy/isotropy transition, the membranes can be served as either responsive permeable membrane or signal expression membrane, thus realizing responsive liquids separation and permeation with satisfactory separation efficiency (>99.90%) and flux (~60 L/m2·h), as well as real-time liquid signal expression with alterable signals. The strategy successfully realizes functional diversity taking advantage of the responsive patterned membranes, which could open up a new door to design superwetting materials for flexible and space-saving applications in narrow working environments.

3.
BMC Public Health ; 20(1): 471, 2020 Apr 10.
Artigo em Inglês | MEDLINE | ID: mdl-32272931

RESUMO

BACKGROUND: The multidimensional Positive Mental Health Instrument (PMHI) has 47 items and six subscales. This study aimed to develop and validate a short unidimensional version of the PMHI among Singapore's adult resident population. METHODS: Using pooled data from three earlier studies (n = 1050), PMHI items were reduced by Partial Credit Rasch Model (PCRM) runs in a random split-half sample, while psychometric properties of the resulting measure were tested through confirmatory factor analysis (CFA), item response theory-graded response model and internal consistency reliability in the other half. Its reliability, construct and concurrent validity, agreement with the original scale, floor and ceiling effect, and scale estimates were further investigated in an external representative general population sample (n = 1925). RESULTS: The average age of the participants was around 41 years. Four PCRM re-runs for item selection resulted in a 6-item unidimensional Rapid PMHI (R-PMHI). CFA confirmed the unidimensional structure of the R-PMHI in the internal (RMSEA = 0.075, CFI = 0.985, TLI = 0.974) and external (RMSEA = 0.051, CFI = 0.992, TLI = 0.987) validation samples. In the external validation sample, the R-PMHI met concurrent validity criteria, showing high agreement with the 47-item version with intra-class correlation coefficient of 0.872 (95% CI: 0.861 to 0.882) and low floor and ceiling effects. Weight-adjusted mean (SE, 95% CI) R-PMHI score in the population was 4.86 (0.2, 4.82-4.90). CONCLUSION: The unidimensional 6-item R-PMHI offers brevity over the original multidimensional measure while appropriately representing the positive mental health construct. Prospective studies are needed to assess its responsiveness and test-retest reliability.


Assuntos
Transtornos Mentais/diagnóstico , Saúde Mental , Escalas de Graduação Psiquiátrica , Inquéritos e Questionários , Adulto , Idoso , Estudos Transversais , Análise Fatorial , Feminino , Humanos , Masculino , Transtornos Mentais/epidemiologia , Pessoa de Meia-Idade , Psicometria , Reprodutibilidade dos Testes , Singapura/epidemiologia , Adulto Jovem
4.
Mater Sci Eng C Mater Biol Appl ; 111: 110804, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32279750

RESUMO

Halloysite nanotubes (HNTs) are a kind of aluminosilicate clay with a unique hollow tubular structure that has been intensively explored for various applications especially in biomedical fields owing to their excellent biocompatibility, biodegrading potential and low cost. Surface modification of HNTs with functional polymers will greatly improve their properties and endow new functions for biomedical applications. In this work, a light-induced reversible addition-fragmentation chain transfer (RAFT) polymerization was introduced to successfully prepare HNTs based fluorescent HNTs/poly(PEGMA-Fl) composites in the presence of oxygen using diacrylate-fluorescein and poly (ethylene glycol) methyl ether methacrylate (PEGMA) as the monomers. Without other catalysts, heating, and deoxygenation procedure, the polymerization process can take place under mild conditions. Besides, owing to the introduction of fluorescein and PEGMA on the surface of HNTs, the resultant HNTs/poly(PEGMA-Fl) composites display high water dispersibility and stable fluorescence. The results from cell viability examination and confocal laser scanning microscopy also demonstrated that HNTs/poly(PEGMA-Fl) composites could be internalized by L929 cells with bright fluorescence and low cytotoxicity. Taken together, we developed a novel photo-initiated RAFT polymerization method for the fabrication of HNTs based fluorescent polymeric composites with great potential for biomedical applications. More importantly, many other multifunctional HNTs based polymer composites could also be fabricated through a similar strategy owing to good designability of RAFT polymerization.

5.
Mater Sci Eng C Mater Biol Appl ; 109: 110442, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32228901

RESUMO

Carbon nanotubes (CNTs) are a novel type of one-dimensional carbon nanomaterials that have been widely utilized for biomedical applications such as drug delivery, cancer photothermal treatment owing to their high surface area and unique interaction with cell membranes. However, their biomedical applications are still impeded by some drawbacks, including poor water dispersibility, lack of functional groups and toxicity. Therefore, surface modification of CNTs to overcome these issues should be importance and of great interest. In this work, we reported for the first time that CNTs could be surface modification through the combination of Diels-Alder (D-A) reaction and redox polymerization, this strategy shows the advantages of mild reaction conditions, water tolerance, low temperature and hydroxyl-surfaced initiator. In this modification procedure, the hydroxyl groups were introduced on the surface of CNTs through the D-A reaction that was adopted for grafting the copolymers, which were initiated by the Ce(IV)/HNO3 redox system using the hydrophilic and biocompatible poly(ethylene glycol) methyl ether methacrylate (PEGMA) and carboxyl-rich acrylic acid (AA) as monomers. The final CNTs-OH-PAA@PEGMA composites were characterized by a series of characterization techniques. The drug loading and release results suggested that anticancer agent cis­platinum (CDDP) could be loaded on CNTs-OH-PAA@PEGMA composites through coordination with carboxyl groups and drug release behavior could be controlled by pH. More importantly, the cell viability results clearly demonstrated that CNTs-OH-PAA@PEGMA composites displayed low toxicity and the drug could be transported in cells and still maintain their therapeutic effects.

6.
Environ Sci Technol ; 54(8): 5150-5158, 2020 Apr 21.
Artigo em Inglês | MEDLINE | ID: mdl-32186176

RESUMO

Solar distillation through photothermal evaporators has approached solar light energy (E1) limit under no solar concentration but still suffers from modest vapor and clean water production. Herein, a nature-inspired low-tortuosity three-dimensional (3D) evaporator is demonstrated to significantly improve water production. The solar evaporator, prepared from polypyrrole-modified maize straw (PMS), had upright vascular structures enabling high water lifting and horizontal microgaps facilitating broad water distribution to the out-surface. Consequently, this novel PMS evaporator dramatically enhanced the utilization of the solar heat energy stored in the environment (E2) for promoting evaporation. The maximum vapor generation rate of a single PMS respectively increases 2.5 and 6 times compared with the conventional 3D evaporators and the planar evaporators of an identical occupied area. Consequently, a scaled-up PMS array achieved a state-of-the-art vapor generation rate of 3.0 L m-2 h-1 (LMH) under a simulated condition and a record-high clean water production of 2.2 LMH for actual seawater desalination under natural conditions (1 sun intensity). This breakthrough reveals great potentials for cost-effective freshwater production as well as the rational design of high-performance photothermal evaporators for solar distillation.

7.
Artigo em Inglês | MEDLINE | ID: mdl-32134257

RESUMO

Electrically conducting films are important for the development of modern electronics. However, most of these conducting films become susceptible to structure fractures under complex deformations or accidental damages, causing the devices to fail to work. Inspired by the self-healing capability of creatures, we developed a self-healing, thermostable, and electrically conducting film that can be healed by electricity by paving aligned carbon nanotube (CNT) sheets onto the surface of liquid crystal elastomer composite films. The aligned CNT sheets make the composites conductive, so the composites can be healed not only by light but also by electricity after breaking. The scratches on the self-healing film can be healed easily under a voltage of 1.18 V/mm because of the electro-thermal effect of aligned CNT sheets. The healed film has almost the same mechanical properties compared to the pristine sample. The electrical and mechanical self-healing of the film is derived from the electrical reconnection of carbon nanotubes and transesterification-induced topology change of the network, respectively. We further demonstrated soft actuators and high-performance supercapacitors based on the prepared self-healing conducting films. This method for preparing self-healing conducting films enables the development of self-healing electronics.

8.
ACS Appl Mater Interfaces ; 12(14): 16104-16113, 2020 Apr 08.
Artigo em Inglês | MEDLINE | ID: mdl-32186840

RESUMO

Fullerenes are known as highly efficient scavengers for reactive oxygen species (ROSs). In this study, a carnosine-modified fullerene derivative (C60-Car) was synthesized via a one-step nucleophilic addition reaction. C60-Car forms nanoparticles (NPs) readily in water at neutral pH and room temperature through self-assembly. The C60-Car NPs were found to possess good water solubility, biocompatibility, and excellent ROSs scavenging capability. The scavenging efficiency of ROSs is as high as 92.49% and significantly better than that of hydroxyfullerene (C60-OH NPs, 70.92%) and l-carnosine. Furthermore, C60-Car NPs showed strong cytoprotective ability against H2O2-induced damage to the normal human fetal hepatocyte cells (L-02) and human epidermal keratinocytes-adult (HEK-a) cells at a lower concentration of 2.5 µM. In contrast, C60-OH NPs showed a minor cytoprotective effect on cells at a high concentration of 10 µM. The excellent properties of such a fullerene derivative, C60-Car, can be attributed largely to the involvement of l-carnosine with biological activity and antioxidant property, which make it better for biomedicine, and it may provide a new strategy for mitigating acute oxidative stress based on fullerene materials.

9.
J Mater Chem B ; 8(13): 2673-2688, 2020 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-32147674

RESUMO

An effective treatment for spinal cord injury (SCI) remains a severe clinical challenge due to the intrinsically limited regenerative capacity and complex anatomical structure of the spinal cord. The combination of biomaterials, which serve as scaffolds for axonal growth, cells and neurotrophic factors, is an excellent candidate for spinal cord regeneration. Herein, a new micropatterned conductive electrospun nanofiber mesh was constructed with poly{[aniline tetramer methacrylamide]-co-[dopamine methacrylamide]-co-[poly(ethylene glycol) methyl ether methacrylate]}/PCL (PCAT) using a rotation electrospinning technology. The aim was to study the synergistic effects of electrical stimulation (ES) and a micropatterned conductive electrospun nanofiber mesh incorporated with nerve growth factor (NGF) on the differentiation of rat nerve stem cells (NSCs). The hydrophilicity of the conductive nanofiber mesh could be tailored by changing the dopamine (DA) and aniline tetramer (AT) content from 19° to 79°. A favorable electroactivity and conductivity was achieved by the AT segment of PCAT. The as-fabricated micropatterned electrospun nanofiber mesh possessed a regularly aligned valley and ridge structure, and the diameter of the nanofiber was 312 ± 58 nm, while the width of the valley and ridge was measured to be 210 ± 17 µm and 200 ± 16 µm, respectively. The growth and neurite outgrowth of differentiated NSCs were observed along the valley of the micropatterned nanofiber mesh. In addition, the NGF loaded micropatterned conductive electrospun nanofiber mesh combined with ES exhibited the highest cell viability, and effectively facilitated the differentiation of NSCs into neurons and suppressed the formation of astrocytes, thus exhibiting a great application potential for nerve tissue engineering.

10.
Sci Rep ; 10(1): 4237, 2020 Mar 06.
Artigo em Inglês | MEDLINE | ID: mdl-32144312

RESUMO

Zinc oxide (ZnO) is a stable, direct bandgap semiconductor emitting in the UV with a multitude of technical applications. It is well known that ZnO emission can be shifted into the green for visible light applications through the introduction of defects. However, generating consistent and efficient green emission through this process is challenging, particularly given that the chemical or atomic origin of the green emission in ZnO is still under debate. In this work we present a new method, for which we coin term desulfurization, for creating green emitting ZnO with significantly enhanced quantum efficiency. Solution grown ZnO nanowires are partially converted to ZnS, then desulfurized back to ZnO, resulting in a highly controlled concentration of oxygen defects as determined by X-ray photoelectron spectroscopy and electron paramagnetic resonance. Using this controlled placement of oxygen vacancies we observe a greater than 40-fold enhancement of integrated emission intensity and explore the nature of this enhancement through low temperature photoluminescence experiments.

11.
Biochem Biophys Res Commun ; 524(2): 516-522, 2020 Apr 02.
Artigo em Inglês | MEDLINE | ID: mdl-32014253

RESUMO

Bone marrow mesenchymal stem cells (BMSCs), which have multipotential differentiation and self-renewal ability, have been becoming an attractive source of seed cells for bone tissue engineering. Nonetheless, the precise underlying mechanisms of osteogenesis of BMSCs have not been fully understood. Retinoic acid-induced gene 3 (RAI3) has been found to play important roles in mesenchymal stem cells (MSCs) adipogenesis in our previous study. However, its function in the osteogenic differentiation of BMSCs remains unknown. In this study, we found that RAI3 was significantly reduced in osteogenically differentiated BMSCs; RAI3 knockdown promoted osteogenesis of BMSCs both in vitro and in vivo. Moreover, we found RAI3 knockdown significantly upregulated the expression level of phosphorylated signal transducer and activator of transcription 3 (p-STAT3), and AG-490 which can inhibit the STAT3 signaling reversed the enhancing effect of RAI3 knockdown on the osteogenic differentiation of BMSCs. These results suggest that RAI3 plays important roles in BMSCs osteogenesis with an involvement of the STAT3 signaling, which might open a new avenue to explore BMSCs osteogenesis for the application of BMSCs in bone regeneration.

12.
Nanoscale ; 2020 Feb 04.
Artigo em Inglês | MEDLINE | ID: mdl-32016223

RESUMO

MXenes are a new type of two-dimensional (2D) transition metal carbide or carbonitride material with a 2D structure similar to graphene. The general formula of MXenes is Mn+1XnTx, in which M is an early transition metal element, X represents carbon, nitrogen and boron, and T is a surface oxygen-containing or fluorine-containing group. These novel 2D materials possess a unique 2D layered structure, large specific surface area, good conductivity, stability, and mechanical properties. Benefitting from these properties, MXenes have received increasing attention and emerged as new substrate materials for exploration of various applications including, energy storage and conversion, photothermal treatment, drug delivery, environmental adsorption and catalytic degradation. The progress on various applications of MXene-based materials has been reviewed; while only a few of them covered environmental remediation, surface modification of MXenes has never been highlighted. In this review, we highlight recent advances and achievements in surface modification and environmental applications (such as environmental adsorption and catalytic degradation) of MXene-based materials. The current studies on the biocompatibility and toxicity of MXenes and related materials are summarized in the following sections. The challenges and future directions of the environmental applications of MXene-based materials are also discussed and highlighted.

13.
J Colloid Interface Sci ; 567: 136-144, 2020 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-32045735

RESUMO

Fluorescence imaging and magnetic resonance imaging have been research hotspots for adjuvant therapy and diagnosis. However, traditional fluorescent probes or contrast agents possess insurmountable weaknesses. In this work, we reported the preparation of dual-mode probes based on mesoporous silica nanomaterials (MSNs), which were doped with an aggregation-induced emission (AIE) dye and Gd3+ through a direct sol-gel method. In this system, the obtained materials emitted strong red fluorescence, in which the maximum emission wavelength was located at 669 nm, and could be applied as effective fluorescence probes for fluorescence microscopy imaging. Furthermore, the introduction of Gd3+ made the nanoparticles effective contrast agents when applied in contrast-enhanced magnetic resonance (MR) imaging because they could improve the contrast of MR imaging. The excellent biocompatibility of these nanoparticles, as demonstrated via a typical CCK-8 assay, and their performance in fluorescence cell imaging and MR imaging shows their potential for applications in biomedical imaging.

14.
J Colloid Interface Sci ; 567: 190-201, 2020 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-32058169

RESUMO

Herein a simple and novel approach has been developed for surface modification of delaminate MXene with nano-mixed silver oxide which combined with mussel-inspired chemistry. Surface modification with dopamine as a secondary reaction platform for loading nano-silver compounds for removal of iodine was achieved. The internal structure and morphology were characterized by SEM and TEM. The element content and distribution analysis of EDS and XPS proved that nano silver compounds were successfully supported and uniformly dispersed on the surface of MXene. Then the adsorption batch experiment was carried out, adsorption time, pH and other factors on the adsorption performance of the adsorbents were studied in details. By calculating the enthalpy change, Gibbs free energy and thermodynamic parameters, the adsorption reaction was found to be an exothermic process. The adsorption kinetics measured the maximum adsorption capacity of 80 mg/g and the removal efficiency is as high as 80% and the adsorption equilibrium time has also been improved. The adsorption kinetics were well fitted by pseudo first-order and second-order models. All the above results demonstrated that the composite from mussel-inspired chemistry has excellent adsorption properties towards iodine ions. This study not only deepens the research on the adsorption behavior of iodine adsorption, but also provides new research directions and experimental methods for pseudo-iodine adsorption.

15.
Biofabrication ; 12(2): 025030, 2020 03 23.
Artigo em Inglês | MEDLINE | ID: mdl-32106097

RESUMO

Due to the increasing aging population and the high probability of sport injury among young people nowadays, it is of great demand to repair/regenerate diseased/defected osteochondral tissue. Given that osteochondral tissue mainly consists of a subchondral layer and a cartilage layer which are structurally heterogeneous and mechanically distinct, developing a biomimetic bi-phasic scaffold with excellent bonding strength to regenerate osteochondral tissue is highly desirable. Three-dimensional (3D) printing is advantageous in producing scaffolds with customized shape, designed structure/composition gradients and hence can be used to produce heterogeneous scaffolds for osteochondral tissue regeneration. In this study, bi-layered osteochondral scaffolds were developed through cryogenic 3D printing, in which osteogenic peptide/ß-tricalcium phosphate/poly(lactic-co-glycolic acid) water-in-oil composite emulsions were printed into hierarchically porous subchondral layer while poly(D,L-lactic acid-co-trimethylene carbonate) water-in-oil emulsions were printed into thermal-responsive cartilage frame on top of the subchondral layer. The cartilage frame was further filled/dispensed with transforming growth factor-ß1 loaded collagen I hydrogel to form the cartilage module. Although the continuously constructed osteochondral scaffolds had distinct microscopic morphologies and varied mechanical properties at the subchondral zone and cartilage zone at 37 °C, respectively, the two layers were closely bonded together, showing excellent shear strength and peeling strength. Rat bone marrow derived mesenchymal stem cells (rBMSCs) exhibited high viability and proliferation at both subchondral- and cartilage layer. Moreover, gradient rBMSC osteogenic/chondrogenic differentiation was obtained in the osteochondral scaffolds. This proof-of-concept study provides a facile way to produce integrated osteochondral scaffolds for concurrently directing rBMSC osteogenic/chondrogenic differentiation at different regions.

16.
Mater Sci Eng C Mater Biol Appl ; 108: 110413, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31923965

RESUMO

Nanodiamond (ND) has been widely studied as a new type of carbon nanomaterials that is expected to be used as a promising candidate in various fields especially in the field of biomedicine. However, its poor water dispersibility and insufficient controlled release limit its practical applications. In this paper, ND-based composites with pH-responsive hydrazone bonds were successfully prepared by a simple chemical reaction between ester groups and hydrazine hydrate, in which ester groups were conjugated on the surface of ND via thiol-ene click reaction. On the other hand, CHO-PEG and doxorubicin hydrochloride (DOX) were linked on the carriers through formation of hydrazone bonds, resulting in improving water dispersibility and high drug loading capacity. The structure, thermal stability, surface morphology and particle size of ND carriers were characterized by different equipment. Results demonstrated that we have successfully prepared these functionalized ND. The release rate of DOX in acidic environment was significantly greater than that in normal physiological environment. More importantly, cell viability and optical imaging results showed that ND-based composites possess good biocompatibility, therapeutic effect, and could successfully transport DOX to HepG2 cells. Considering the above results, we believe that our new ND carriers will become promising candidates for intracellular controlled drug delivery and cancer treatment.

17.
Mater Sci Eng C Mater Biol Appl ; 108: 110424, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31923979

RESUMO

Fluorescent hydroxyapatite (HAp) nanoparticles have received significant attention in biomedical fields due to their outstanding advantages, such as low immunogenicity, excellent biocompatibility and biodegradability. However, fluorescent HAp nanoparticles with well controlled size and morphology are coated with hydrophobic molecules and their biomedical applications are largely restricted by their poor dispersibility in physiological solutions. Therefore, surface modification of these hydrophobic fluorescent HAp nanoparticles to render them water dispersibility is of utmost importance for biomedical applications. In this work, we reported for the first time for preparation of water-dispersible hydrophilic fluorescent Eu3+-doped HAp nanoparticles (named as HAp-PEOTx) through the cationic ring-opening polymerization using hydrophilic and biocompatible 2-ethyl-2-oxazoline (EOTx) as the monomer. The characterization techniques, such as nuclear magnetic resonance (NMR) spectroscopy, transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) have been used to characterize these samples. Results confirmed that we could successfully obtain the hydrophilic fluorescent HAp-PEOTx composites through the strategy described above. These fluorescent HAp-PEOTx composites display great water dispersibility, unique fluorescent properties and excellent biocompatibility, making them promising for in vitro bioimaging applications.

18.
Mater Sci Eng C Mater Biol Appl ; 108: 110376, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31924027

RESUMO

As potential alternatives to conventional semiconductor quantum dots, fluorescent carbon quantum dots (CQDs) have received increasing research attention in biomedical fields owing to their splendid advantages of low cytotoxicity, strong fluorescence and excellent water dispersion. However, the preparation procedures of CQDs with designable chemical properties and functions are complicated and low efficient. In this work, we developed a facile, economical and straightforward strategy to prepare CQDs by a one-step thiol-ene click reaction between multiwalled carbon nanotubes (CNTs) and thiomalic acid (TA). The successful synthesis of CQDs was confirmed by a series of characterization data. The results manifested that CQDs were well combined with TA through surface thiol-ene click chemistry. In addition, the optical property is also desirable, the maximum emission wavelength was located in 500 nm and CQDs still could emit strong blue fluorescent light after irradiation with UV irradiation for 3 h. Besides, the pH value makes no significant changes for fluorescence emission wavelength of CQDs and CQDs can emit strongest fluorescence in weak acid solution. Furthermore, CQDs could be internalized by cells and show great cell dyeing performance and low cytotoxicity. All these features imply that TA functionalized CQDs possess great potential for biological imaging. The one-step thiol-ene click strategy provided a novel tool to prepare functionalized CQDs with great potential for biomedical applications.

19.
Artigo em Inglês | MEDLINE | ID: mdl-31903678

RESUMO

Thermal reprogrammability is essential for new-generation large dry soft actuators, but the realization sacrifices the favored actuation performance. The contradiction between thermal reprogrammability and stability hampers efforts to design high-performance soft actuators to be robust and thermally adaptable. Now, a strategy has been developed that relies on repeatedly switching on/off thermal reprogrammability in liquid-crystalline elastomer (LCE) actuators to resolve this problem. By post-synthesis swelling, a latent siloxane exchange reaction can be induced in the common siloxane LCEs (switching on), enabling reprogramming into on-demand 3D-shaped actuators; by switching off the dynamic network by heating, actuation stability is guaranteed even at high temperature (180 °C). Using partially black-ink-patterned LCEs, selectively switching off reprogrammability allows integration of completely different actuation modes in one monolithic actuator for more delicate and elaborate tasks.

20.
ACS Appl Mater Interfaces ; 12(5): 6309-6318, 2020 Feb 05.
Artigo em Inglês | MEDLINE | ID: mdl-31934738

RESUMO

Damage to the responsive superwetting material by external stimuli during the responsive process has been a ticklish question in recent years. We overcome this barrier by imitating a peanut leaf and designing a humidity-responsive MIL-100 (Fe)/octadecylamine-coated stainless steel mesh (HR-MOS). Such a material shows superhydrophilicity when ambient humidity is higher than saturated humidity, while it shows superhydrophobicity and high adhesion to water when ambient humidity is lower than saturated humidity. The peanut leaf-like two-level nanostructure of MIL-100 (Fe) is speculated as the principal factor to bring about the binary synergy wettability of the material. Accordingly, the material can realize humidity-controlled separation of at least 12 types of emulsions along with satisfactory durability. The responsive condition of the material is mild and green, which does lower damage to the material and environment. This strategy is the first to realize humidity-responsive wettability transition and provides a novel approach for manually controlled environmental protection.

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