An optical trap forms a restoring optical force field to immobilize and manipulate tiny objects. A fiber optical trap is capable of establishing the restoring optical force field using one or a few pieces of optical fiber, and it greatly simplifies the optical setup by removing bulky optical components, such as microscope objectives from the working space. It also inherits other major advantages of optical fibers: flexible in shape, robust against disturbance, and highly integrative with fiber-optic systems and on-chip devices. This review will begin with a concise introduction on the principle of optical trapping techniques, followed by a comprehensive discussion on different types of fiber optical traps, including their structures, functionalities and associated fabrication techniques. A brief outlook to the future development and potential applications of fiber optical traps is given at the end.
Perovskite-based solar cells with high power conversion efficiencies (PCEs) are currently being demonstrated in solid-state device designs. Their elevated performances can possibly be attained with different non-standard geometries, for example, the fiber-shaped perovskite solar cells, in the light of careful design and engineering. Fiber-shaped solar cells are promising in smart textiles energy harvesting towards next-generation electronic applications and devices. They can be made with facile process and at low cost. Recently, fiber-shaped perovskite solar devices have been reported, particularly with the focus on the proof-of-concept in such non-traditional architectures. In this line, there are so many technical aspects which need to be addressed, if these photovoltaic (PV) cells are to be industrialized and produced massively. Herein, a well-organized and comprehensive discussion about the reported devices in this arena is presented. The challenges that need to be addressed, the possible solutions and the probable applications of these PV cells are also discussed. More still, the perovskite fiber-shaped PV cells with other fiber PV devices reported in literature in terms of their scope, characteristic designs, performances, and other technical considerations have been summarised.
Developing bioprotective materials with bactericidal activity is of great significance since it can effectively keep healthcare workers from infection by emerging infectious diseases; however, this is still a big challenge. Herein, we fabricate a novel rechargeable N-halamine antibacterial material by functionalizing electrospun poly(vinyl alcohol-co-ethylene) (EVOH) nanofibers with dimethylol-5,5-dimethylhydantoin (DMDMH). The premise of the design is that the N-halamine compound, DMDMH, can be covalently grafted on the nanofibers, endowing the EVOH nanofibrous membranes (ENM) with rechargeable and durable bactericidal activity. The as-prepared DMDMH functionalized ENM (EDNM) render rechargeable chlorination capacity (> 2000 ppm), high inactivation efficacy against bacteria (> 99.9999% within 3 min), high filtration efficiency (> 99.5%) under low air resistance, and robust mechanical properties, which are due to the synergistic effect of the unique characters of N-halamines and electrospun nanofibrous architecture. The successful synthesis of the N-halamine antibacterial membranes can serve as a functional layer of protective equipment that capable of inactivating and intercepting pathogenic bioaerosols, providing new ways into the development of new-generation antibacterial bioprotective materials.
A novel three-tier composite membrane based on highly porous nanofibrous substrate was demonstrated for efficient isopropanol dehydration by pervaporation. Here, polyethyleneimine (PEI) modified graphene oxide (GO) sheets were vacuum-assistant assembled onto porous electrospun polyacrylonitrile (PAN) nanofibrous substrate to achieve a smooth, hydrophilic and compact PEI-GO intermediate layer. The introduction of PEI chains endowed GO interlayer with sufficient interaction for bonding adjacent GO nanosheets to enhance stability in water/isopropanol mixture and also with the ascended interlamellar space to improve the water-sorption ability due to the abundant active amino groups. Benefiting from PEI-GO layer, a defect-free sodium alginate (SA) skin layer could be facilely manufactured with elaborately controlled thickness as thin as possible in order to reduce mass transfer resistant and enhance permeability maximally. Meanwhile, the interlayer would also contribute to enhance interfacial adhesion to promote the structure integrity of three-tier thin-film nanofibrous composite (TFNC) membrane in pervaporation dehydration process. After fine-tuning of membrane preparation process, the SA/PEI(75)-GO-60/PAN TFNC membrane exhibited competitive pervaporation performance with the permeate flux of 2009 g/m2 h and the separation factor of 1276 operated at 70 °C for dehydration of 90 wt% isopropanol solution. The unique three-tier composite membrane structure suggested an effective and facile approach to design novel membrane structure for further improvement of pervaporation performance.
In this study, we prepared paclitaxel/chitosan (PTX/CS) nanosuspensions (NSs) with different mass ratios of PTX and CS (1.5:2, 2:2, and 2.5:2), for controlled drug delivery purposes. For attachment and dispersion in water medium, a simple ultrasonic disruption technique was employed. The water-dispersed PTX/CS NSs exhibited a rod-shape morphology with an average diameter of 170–210 nm and average length of about 1–10 µm. Transmission electron microscopy, differential scanning calorimetry and X-ray diffraction indicated that the obtained PTX/CS NSs contain a nanocrystalline PTX phase. It was also inferred that presence of CS can promotes the crystalline nature of PTX up to 80%. In addition, efficiency of PTX loading reached over 85% in freeze-dried PTX/CS NSs, showing a slow rate of drug release in vitro for 8 days. The MTT and LDH assessments revealed that PTX/CS NSs significantly inhibit the growth of tumor cells (HeLa), while it is slightly toxic for the normal cells (NIH/3T3). Therefore, PTX/CS NSs is suggested as a potential nanodrug delivery system for cancer therapy.
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