A highly efficient light-driven photocatalytic TiO2–Au Janus micromotor with wireless steering and velocity control is described. Unlike chemically propelled micromotors which commonly require the ...addition of surfactants or toxic chemical fuels, the fuel-free Janus micromotor (diameter ∼1.0 μm) can be powered in pure water under an extremely low ultraviolet light intensity (2.5 × 10–3 W/cm2), and with 40 × 10–3 W/cm2, they can reach a high speed of 25 body length/s, which is comparable to common Pt-based chemically induced self-electrophoretic Janus micromotors. The photocatalytic propulsion can be switched on and off by incident light modulation. In addition, the speed of the photocatalytic TiO2–Au Janus micromotor can be accelerated by increasing the light intensity or by adding low concentrations of chemical fuel H2O2 (i.e., 0.1%). The attractive fuel-free propulsion performance, fast movement triggering response, low light energy requirement, and precise motion control of the TiO2–Au Janus photocatalytic micromotor hold considerable promise for diverse practical applications.
A novel light-driven Au-WO3@C Janus micromotor based on colloidal carbon WO3 nanoparticle composite spheres (WO3@C) prepared by one-step hydrothermal treatment is described. The Janus micromotors can ...move in aqueous media at a speed of 16 μm/s under 40 mW/cm2 UV light due to diffusiophoretic effects. The propulsion of such Au-WO3@C Janus micromotors (diameter ∼ 1.0 μm) can be generated by UV light in pure water without any external chemical fuels and readily modulated by light intensity. After depositing a paramagnetic Ni layer between the Au layer and WO3, the motion direction of the micromotor can be precisely controlled by an external magnetic field. Such magnetic micromotors not only facilitate recycling of motors but also promise more possibility of practical applications in the future. Moreover, the Au-WO3@C Janus micromotors show high sensitivity toward extremely low concentrations of sodium-2,6-dichloroindophenol (DCIP) and Rhodamine B (RhB). The moving speed of motors can be significantly accelerated to 26 and 29 μm/s in 5 × 10–4 wt % DCIP and 5 × 10–7 wt % RhB aqueous solutions, respectively, due to the enhanced diffusiophoretic effect, which results from the rapid photocatalytic degradation of DCIP and RhB by WO3. This photocatalytic acceleration of the Au-WO3@C Janus micromotors confirms the self-diffusiophoretic mechanism and opens an opportunity to tune the motility of the motors. This work also offers the light-driven micromotors a considerable potential for detection and rapid photodegradation of dye pollutants in water.
In modern society, traffic and transportation and the manufacturing industry and construction industries continuously release large amounts of dust and particles into the atmosphere, which can cause ...heavy air pollution, leading to health hazards. The haze disaster, a serious problem in developing countries such as China and India, has become one of the main issues of global environmental pollution in recent decades. Many air filtration technologies have been developed. Air filtration using electrospun fibers that intercept fine particles/volatile organic gases/bacterium is a relatively new, but highly promising, technique. Due to their interconnected nanoscale pore structures, highly specific surface areas, fine diameters, and porous structure as well as their ability to incorporate active chemistry on a nanoscale surface, electrospun fibers are becoming a promising versatile platform for air filtration. In this review, following a short introduction concerning the need for air filtration and filtration theory and mechanism, electrospun nanofibers membranes for air filtration have been highlighted, including the preparation (electrospinning process) and the parameters relevant to filtration efficacy. Additionally, various types (function) of the electrospun air filtration membranes have been classified in detail. Furthermore, their potential in the filtration of fine particles and chemical pollutants has been discussed. Finally, the challenges of their practical application and the future prospects have been summarized. Given that some advanced electrospun air filtration nanofibrous membranes exist for treating different contaminants from various types of polluted atmosphere, it is believed that they should make a significant contribution in protection against air pollution.
Various types and properties of the electrospun nanofibrous membranes for different contributions to remove airborne contaminants.
Tissue engineering small diameter artificial blood vessel is an indispensable graft for repairing extremity arterial injury. Previous researches demonstrated that suitable porosity and matching ...mechanical properties are two keys for tubular tissue reconstruction. In this study, we fabricated a fabric reinforced small diameter tubular graft (PPTG) from PLGA fabric and three-dimensional porous PEEUU with a structure of the bionic extracellular matrix for transplanting in situ combined braiding and thermally induced phase separation (TIPS). The prepared PPTG presented smooth and dense inner surface, fluffy and porous grafts wall, and tubular PLGA fabric evenly dispersed PEEUU matrix, which provide mechanical support for PPTG. The mechanical tests and hemolysis results showed that PPTG possess matched mechanical properties with autologous blood vessels and stable blood compatibility. Six weeks after rabbits’ carotid artery defect replacement indicated that there were no blockage occurred for PPTG group. Histological staining exhibited positive expression of endothelial cells on the inner surface of PPTG and distinct smooth muscle in the wall of PPTG, which migrated from peripheral tissues and flowing blood. Therefore, this fabric reinforced small diameter tubular graft provides a solution for endothelialization and tissue regeneration and have a potential application in vascular trauma.
A fabric reinforced small diameter tubular graft from PLGA fabric and three-dimensional porous PEEUU with a structure of the bionic extracellular matrix exhibited matched mechanical properties, especially they demonstrate excellent performance to induce the migration of host cells to the wall of tubular graft and effective anti-thrombosis properties in rabbit carotid artery defect. Display omitted
Light-driven synthetic micro-/nanomotors have attracted considerable attention in recent years due to their unique performances and potential applications. We herein demonstrate the dye-enhanced ...self-electrophoretic propulsion of light-driven TiO
2
–Au Janus micromotors in aqueous dye solutions. Compared to the velocities of these micromotors in pure water, 1.7, 1.5, and 1.4 times accelerated motions were observed for them in aqueous solutions of methyl blue (10
−5
g L
−1
), cresol red (10
−4
g L
−1
), and methyl orange (10
−4
g L
−1
), respectively. We determined that the micromotor speed changes depending on the type of dyes, due to variations in their photodegradation rates. In addition, following the deposition of a paramagnetic Ni layer between the Au and TiO
2
layers, the micromotor can be precisely navigated under an external magnetic field. Such magnetic micromotors not only facilitate the recycling of micromotors, but also allow reusability in the context of dye detection and degradation. In general, such photocatalytic micro-/nanomotors provide considerable potential for the rapid detection and “on-the-fly” degradation of dye pollutants in aqueous environments.
Thermoresponsive polymers are of great importance in numerous nanotechnological and biomedical applications. Compared to polymers that undergo a lower critical solution temperature (LCST) phase ...transition in aqueous solution, i.e., demixing occurs upon heating, polymers exhibiting the reversed upper critical solution temperature (UCST) behavior in aqueous solution have been much less documented as it is more challenging to achieve this behavior in aqueous solutions. Furthermore, the high sensitivity of UCST behavior to minor variation in polymer structure and solution composition hampered the development of applications based on these polymers 18. However, polymers with UCST transition in alcohol/water solvent mixtures are more commonly reported and exhibit promising properties for the preparation of ‘smart’ materials. This review will focus on the theory and development of such polymers with UCST behavior in alcohol/water solvent mixtures. By highlighting reported examples of UCST polymers in alcohol/water solvent mixtures, we aim to demonstrate the versatility and potential that such UCST polymers possess as biomedical and ‘smart’ materials.
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•The first reported UV-responsive UCST polymer.•Decreasing UCST transition temperature upon UV-irradiation.•Insights in the effect of solvent polarity on switchable UCST behavior.
A ...series of azobenzene containing copolymers were synthesized by post-modification of poly(methyl methacrylate-co-pentafluorophenyl methacrylate) with an amine-functionalized azobenzene. Light- and thermo-responsive behavior of these copolymers was investigated in ethanol–water solvent mixtures with various amounts of ethanol. The upper critical solution temperature (UCST) of the polymer solutions, resulting from the poly(methyl methacrylate), was found to be highly tunable by the substitution degree of the copolymers as well as the ethanol content of the solvent mixture. In addition, the copolymers are light responsive based on the cis–trans isomerization of the azobenzene group under UV irradiation. The cloud point temperatures (TCP) of the polymer solutions decreased after UV-irradiation due to the higher dipole moment of the cis-isomer of the azobenzene moiety leading to better solubility in ethanol–water solvent mixtures. Furthermore, the UV responsiveness was found to strongly depend on the solvent composition, revealing a higher decrease in cloud point after UV-irradiation in ethanol–water solvent mixture with higher water content. To the best of our knowledge, this is the first reported dual responsive polymer that combines light responsiveness with UCST behavior in aqueous solvent mixtures.
Abstract This study was aimed to explore the longitudinal association of five early life factors (breastfeeding, maternal smoking around birth, birth weight, being born in a multiple birth, and ...adoption) during the in-utero, perinatal, and early childhood development stages with incidence of depression and anxiety in adults aged 40–69 years. We used data from the UK biobank, 5,02,394 participants aged 40–69 years were recruited between 2006 and 2010. Participants provided information on early life exposures through touchscreen questionnaires or verbal interviews at baseline. The primary outcomes, depression, and anxiety, were defined according to the International Classification of Diseases, 10th Revision. Hazard ratios (HR) and 95% confidence intervals (CI) for each factor were reported. During a median follow-up of 13.6 years, 16,502 (3.55%) participants developed depression, and 15,507 (3.33%) developed anxiety. After adjusting for potential confounders, increased risk of depression was found to be significantly associated with non-breastfeeding (HR, 1.08; 95% CI, 1.04–1.13), maternal smoking around birth (HR, 1.19; 95% CI, 1.14–1.23), being born in multiple births (HR, 1.16; 95% CI, 1.05–1.27), low birth weight (HR, 1.14; 95% CI, 1.07–1.22), and being an adoptee (HR, 1.42; 95% CI, 1.28–1.58). Increased risk of anxiety was associated with non-breastfeeding (HR, 1.09; 95% CI, 1.04–1.13), maternal smoking around birth (HR, 1.11; 95% CI, 1.07–1.16), being born in a multiple births (HR, 1.05; 95% CI, 0.95–1.17), low birth weight (HR, 1.12; 95% CI, 1.05–1.20), and being an adoptee (HR, 1.25; 95% CI, 1.10–1.41). Each of these five early life factors can be considered as early life risk factors for incident depression and anxiety in adulthood independently. The dose-response relationship was also observed, suggesting that with an increase in the number of early life risk factors, the likelihood of experiencing depression and anxiety also increased. These findings highlighted the imperative consideration of early life factors in comprehending the susceptibility to mental health disorders later in life, including non-breastfeeding, maternal smoking around birth, being born in multiple births, low birth weight, and being an adoptee.
A simple and environmentally friendly approach for the preparation of graphene nanosheets decorated with silver nanoparticles (Ag NPs) has been developed by gamma irradiation at room temperature. ...Graphene oxide (GO) and silver ions are simultaneously reduced by the electrons generated from the radiolysis of solvent. The addition of ionic liquid plays an important role in GO reduction by scavenging oxidative radicals generated during irradiation. Besides, the ionic liquid also benefits the dispersion and size distribution of Ag NPs. Raman signals of the obtained Ag-reduced graphene oxide are significantly enhanced, exhibiting obvious surface-enhanced Raman scattering activity.
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