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Ocean Salinity Sensing Using Long-Period Fiber Gratings Functionalized with Layer-by-Layer Hydrogels
摘要： Rapid, accurate, and real-time measurements of ocean salinity are of great importance for a host of scientific, commercial, and defense applications. We demonstrate a highly sensitive, fast-responding fiber-optic salinity sensor that integrates long-period fiber gratings (LPFGs) with ionic strength-responsive hydrogel. The submicron-thick hydrogel was synthesized via layer-by-layer electrostatic assembly of partially quaternized poly(4-vinylpyridine) (qP4VP) and poly(acrylic acid), followed by chemical cross-linking. Spectroscopic ellipsometry measurement of a hydrogel made of 37% quaternized qP4VP showed robust and reversible swelling/deswelling in solutions with salt concentrations ranging from 0.4 to 0.8 M (22.8?44.7 g/kg) around pH 8.1. The swelling/deswelling process induced large changes in the refractive index of the hydrogel, leading to resultant shift in the resonance wavelength (RW) of LPFGs. The salinity-dependent optical response of the hydrogel-coated LPFGs is in good agreement with ellipsometry measurement. LPFGs coated with the hydrogel exhibited a sensitivity of 7 nm RW shift/M (125.5 pm/‰) with a measurement time less than 5 s. The shift in the resonance wavelength correlated linearly with salt concentration, making quantification of measured salinity straightforward.
关键词： refractive index,layer-by-layer assembly,hydrogels,ocean salinity sensing,long-period fiber gratings,ionic strength
更新于2025-09-19 17:15:36
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Multifunctional luminescent immuno-magnetic nanoparticles: toward fast, efficient, cell-friendly capture and recovery of circulating tumor cells
摘要： Highly efficient isolation and recovery of viable circulating tumor cells (CTCs) from the blood of patients is an important precondition to address the current dilemma of insufficient CTC studies, and can promote the development of individualized antitumor therapies. Herein, a cell-friendly CTC isolation and recovery nanoplatform with luminescent labelling was established using a layer-by-layer (LbL) assembly technique and a stimulated cellular-release strategy. In particular, the anti-epithelial cell adhesion molecule (anti-EpCAM) antibody was introduced with a disulfide bond-containing linker for further bio-friendly recovery of the CTCs. Quantum dots (QDs) were deposited onto fast magnet-responsive Fe3O4 nanoparticles through a facile LbL assembly method to monitor the capture and recovery process in real time. The obtained PEGylated immuno-magnetic nanospheres (PIMNs) can all be magnetically collected within 2 min. Capture efficiencies above 90% can be achieved from blood samples with 5–200 CTCs per mL after only 1–2 min incubation. Nearly all PIMNs on the surface of the CTCs were detached after 15 min of glutathione (GSH) treatment with the disappearance of QD signals. Recovered CTCs could be directly used for culture (cell viability, 98%), and their invasiveness and migration characteristics remained unchanged. Furthermore, the PIMNs were successfully applied to isolate CTCs in cancer patients’ peripheral blood samples, and an average of 8.6 ± 5.8 CTCs per mL was detected. The results above suggested that PIMNs may serve as a powerful nanoplatform for CTC screening, isolation and recovery.
关键词： layer-by-layer assembly,circulating tumor cells,capture and recovery,Multifunctional luminescent immuno-magnetic nanoparticles,quantum dots,glutathione treatment
更新于2025-09-19 17:15:36
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Layer-by-Layer-Assembled Antifouling Films with Surface Microtopography Inspired by Laminaria japonica
摘要： Marine biofouling is an important obstacle to the development of marine resources. Problems such as huge economic losses caused by biofouling and environmental damage caused by toxic antifouling agents have not been resolved. Therefore, it is of great significance to develop a novel, environmentally friendly antifouling (AF) materials. However, in the marine environment, Laminaria japonica still has excellent antifouling ability in a relatively static state compared to those parade creatures. Inspired by this, this study reports a synergistic effect between surface topography and chemical modification to inhibit marine biofouling. Firstly, the surface of the Laminaria japonica was analyzed and its morphology was reproduced using a simple moulding process. Additionally, the polyelectrolyte layer composed of sodium alginate and (guanidine-hexamethylenediamine-PEI) (poly(GHPEI)) was chemically modified on the isotropic microstructure surface of PDMS replicas by layer-by-layer assembly method. The anti-adhesion ability of the biomimetic material was tested with Nitzschia closterium (N. closterium) (9±5 diatoms mm-2 of N. closterium adhered). Meanwhile, the antifouling performance of the modified films were evaluated by Escherichia coli (E. coli), and its antibacterial ability were as high as 96.2±1.3%. The combination of microtopography and (GHPEI/ALG) * n films endow the coating with excellent antifouling ability.
关键词： marine antifouling,surface microtopography,layer-by-layer assembly,alginate,poly(GHPEI),chemical modifications
更新于2025-09-16 10:30:52
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Layer-by-layer assembly of polyelectrolytes-wrapped multi-walled carbon nanotubes on long period fiber grating sensors
摘要： A new type of long period fiber grating (LPG) sensor coated with polyelectrolytes-wrapped multi-walled carbon nanotube (MWCNT) (PE-CNT) thin film is reported in this study. The novel morphologies of the MWCNT-based nanostructured thin film are observed by scanning electron microscopy characterization. The refractive index and pH sensing behaviors of LPGs with pure (PE)10 thin film and with (PE-CNT)10 thin film, respectively are compared. Results show that for LPG with (PE-CNT)10 thin film the transmission intensity at the resonance wavelength decreases noticeably with the increase of the surrounding refractive index. This is distinct from the sensing mechanism of LPG with (PE)10 thin film, which is based on the resonance wavelength shift. The LPG with a (PE-CNT)10 thin film provides enhanced pH sensitivity compared with that of a (PE)10 thin film. The LPG with (PE-CNT)10 thin film has a fast response rate and a good repeatability, thus demonstrating its strong potentiality for practical monitoring applications.
关键词： layer-by-layer assembly,sensor,thin film,Long period fiber grating,pH sensing,carbon nanotube
更新于2025-09-11 14:15:04
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Interface Engineering of Hematite with Nacre-like Catalytic Multilayers for Solar Water Oxidation
摘要： An efficient water oxidation photoanode based on hematite has been designed and fabricated by tailored assembly of graphene oxide (GO) nanosheets and cobalt polyoxometalates (Co-POM) water oxidation catalysts into a nacre-like multilayer architecture on a hematite photoanode. The deposition of catalytic multilayers provides a high photocatalytic efficiency and photoelectrochemical stability to underlying hematite photoanodes. Compared to the bare counterpart, the catalytic multilayer electrode exhibits a significantly higher photocurrent density and large cathodic shift in onset potential (~ 369 mV) even at neutral pH conditions due to the improved charge transport and catalytic efficiency from the rational and precise assembly of GO and Co-POM. Unexpectedly, the polymeric base layer deposited prior to the catalytic multilayers improves the performance even more by facilitating the transfer of photogenerated holes for water oxidation through modification of the flat band potential of the underlying photoelectrode. This approach utilizing polymeric base and catalytic multilayers provides an insight into the design of highly efficient photoelectrodes and devices for artificial photosynthesis.
关键词： photocatalysis,graphene oxide,layer-by-layer assembly,artificial photosynthesis,polyoxometalate
更新于2025-09-10 09:29:36
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Fabrication of flexible MIL-100(Fe) supported SiO2 nanofibrous membrane for visible light photocatalysis
摘要： Core/shell structured SiO2/MIL-100(Fe) fibrous membrane was prepared for photocatalytic degradation of dyes. The metal organic framework shells of MIL-100(Fe) were decorated on electrospun SiO2 nanofiber surface through layer-by-layer assembly. Fourier-transform infrared spectroscopy and X-ray photoelectron spectroscopy tests confirmed the successful synthesis of the MIL-100(Fe) nanoparticles. The formed SiO2/MIL-100(Fe) catalysts exhibited high catalytic activity towards degradation of Rhodamine B under visible light irradiation. The photocatalytic activity remained above 80% within 90 min illumination after three cycles. Due to the easy preparation and high photocatalytic performance, as well as convenient collection for reuse, the obtained SiO2/MIL-100(Fe) membranes are promising catalysts for practical application.
关键词： Layer-by-layer assembly,Visible light,SiO2/MIL-100(Fe),Dye degradation,Photocatalysis
更新于2025-09-09 09:28:46
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Fabrication of Metal–Organic Framework Thin Films Using Programmed Layer‐by‐Layer Assembly Techniques
摘要： Metal–organic frameworks (MOFs) are a rather new class of crystalline, nanoporous solids that are self-assembled from inorganic, metal or metal-oxo nodes and organic linkers. Powder MOFs are originally developed for gas storage and catalyst applications, but more recently, more advanced applications have used well-defined MOF thin films in electronic, photonic, and sensing devices. MOF thin films for targeted applications can be fabricated on appropriately functionalized substrates using a programmed layer-by-layer (LbL) assembly technique, which yields oriented, highly crystalline MOF thin films (surface-mounted MOFs, SURMOFs). The LbL assembly technique as well as the huge potential of SURMOFs is presented herein. Emerging SURMOF properties related to their heteroepitaxy, postsynthetic modification/crosslinking, lithography, and photoswitching are highlighted.
关键词： lithography,photoswitching,MOF thin film,layer-by-layer assembly,heteroepitaxy
更新于2025-09-04 15:30:14