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Silvera??chitosan nanocomposite as a plasmonic platform for SERS sensing of polyaromatic sulfur heterocycles in oil fuel
摘要： Herein, a silver-chitosan nanocomposite for applications in surface enhanced Raman spectroscopy (SERS) sensing was proposed. It was shown that optically transparent chitosan coatings with 0.8 μm thickness allow penetration of target analytes to silver nanoparticles and the analysis in both polar and nonpolar solvents. Under the chosen conditions, chitosan formed continuously smooth films and coatings stabilizing rough nanostructured metallic surfaces and served as a suitable matrix for immobilization, uniform spreading, and preconcentration of the analytes. Polycyclic aromatic sulfur heterocycles were chosen as target analytes being one of the most important fuel quality markers, hazardous components and the hardest-to-remove impurities. For the most effective immobilization and even distribution of the analytes onto a nanostructured metallic surface, an additional polymer layer of chitosan was found to be needful. The presence of thin films of chitosan resulted in higher reproducibility of SERS spectra as compared to bare nanostructured silver substrates. Additionally, the developed nanocomposite SERS sensors provided the rapid determination of dibenzothiophene and its derivatives in isooctane with the threshold of detection better than 0.1 μM. This approach was successfully applied in the analysis of real fuel samples and the results agreed well with independently measured FTIR and GC-MS data.
关键词： chitosan,nonpolar solvents,polycyclic aromatic sulfur heterocycles,silver nanoparticles,surface enhanced Raman spectroscopy
更新于2025-09-23 15:19:57
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Spectral analysis combined with nonlinear optical measurement of laser printed biopolymer composites comprising chitosan/SWCNT
摘要： Biopolymer composites based on two types of chitosan (chitosan succinate and low-molecular weight chitosan) with single-walled carbon nanotubes (SWCNT) were created by laser printing. SWCNT have good dispersibility in chitosan solutions and therefore, can form relatively homogeneous films that was shown in scanning electron microscopy images. For the studies film composites were formed under the action of laser radiation on aqueous dispersion media. Study of the nonlinear optical process during the interaction of laser radiation with a disperse media has shown that low-molecular chitosan has a large nonlinear absorption coefficient of 17 cm/GW, while the addition of SWCNT lead to a significant increase up to 902 cm/GW. The threshold intensity for these samples was 5.5 MW/cm2 with nanotubes. If intensity exceeds the threshold value, nonlinear effects occur, which, in turn, lead to the transformation of a liquid into a solid phase. Characterization of films by FTIR and Raman spectroscopy indicated arising molecular interactions between chitosan and SWCNT detected as a small frequency shift and a change in the shape of radial breathing mode (RBM). The results indicate the possibility using aqueous dispersion media based on chitosan and SWCNT to create three-dimensional films and scaffolds for tissue engineering by laser printing.
关键词： Tissue engineering,Carbon nanotubes,Nonlinear optical properties,Chitosan,Spectroscopy
更新于2025-09-23 15:19:57
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Influence of 1-methyl-3-propylimidazolium iodide ionic liquid on the performance of dye-sensitized solar cell using hexanoyl chitosan/poly(vinyl chloride) based polymer electrolyte
摘要： Polymer electrolytes based on hexanoyl chitosan/poly(vinyl chloride) (PVC) were prepared by employing sodium iodide (NaI) as the doping salt and 1-methyl-3-propylimidazolium iodide (MPImI) as the ionic liquid. The concentration of MPImI was varied from 2 to 10 wt.% while the amount of polymer and salt were kept constant. The effect of MPImI on the crystallinity, structural and conductivity properties of hexanoyl chitosan/PVC-NaI have been investigated. XRD results show that MPImI disrupts the crystallinity of polymer matrix while FTIR results show the existence of interactions among components in hexanoyl chitosan/PVC-NaI-MPImI. Polymer electrolyte without MPImI shows the highest conductivity of 1.5 × 10?5 S cm?1 at 303 K. Upon incorporation of MPImI, increment in conductivity can be observed. The hexanoyl chitosan/PVC-NaI-MPImI electrolytes were assembled into dye-sensitized solar cells (DSSCs) and the dependence of DSSCs performance on MPImI concentration has been investigated. DSSC with 8 wt.% of MPImI shows the energy conversion efficiency, η of 4.55 % with short circuit current density, Jsc of 10.34 mA cm?2 and open circuit voltage, Voc of 0.74 V.
关键词： PVC,Conductivity,Polymer electrolyte,Dye-sensitized solar cells,Hexanoyl chitosan
更新于2025-09-23 15:19:57
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Plasmonic Gold Nanorattle Impregnated Chitosan Nanocarrier for Stimulus Responsive Theranostics
摘要： Herein, a stimulus-responsive theranostic nanosystem comprising gold nanorattles (AuNRTs), having a solid octahedron core and thin porous cubic shell, encapsulated within chitosan nanocarriers (CS-AuNRT) has been reported. Due to the plasmonic AuNRTs, CS-AuNRT demonstrated unique features of near infrared (NIR) absorbance and accessible intrinsic electromagnetic “hot spots” arising due to coupling of inner solid core and outer porous shell. These properties enabled CS-AuNRTs to be used for NIR-responsive drug delivery, photothermal therapy, and surface enhanced Raman scattering (SERS) based bioimaging. Following loading of chemotherapeutic drug doxorubicin (DOX) within AuNRTs along with a phase changing material (PCM), application of NIR irradiation resulted in photothermal melting of the PCM and simultaneous payload release in the surrounding medium. Although being nontoxic themselves, CS-AuNRTs with or without loaded DOX could mount signi?cant cell death in breast cancer cell line (MCF-7) in the presence of NIR light as external stimulus. The oxidative stress generated by DOX-loaded and empty CS-AuNRTs upon NIR irradiation were con?rmed by ?ow-cytometric determination of intracellular reactive oxygen species (ROS). Further, the ROS-led induction of apoptosis in treated MCF-7 cells was established from characteristic nuclear fragmentation, morphological changes and membrane blebbing as observed through confocal ?uorescence and scanning electron microscopy. Thus, with NIR responsive chemo-photothermal therapy and SERS based bioimaging, the present nanocarrier system holds potential for cancer theranostics.
关键词： bioimaging,drug delivery,photothermal therapy,stimuli responsive,nanorattle,chitosan nanoparticle
更新于2025-09-19 17:13:59
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Microstructured optical fiber based Fabrya??P??rot interferometer as a humidity sensor utilizing chitosan polymeric matrix for breath monitoring
摘要： This study reports a method for humidity sensing based on a specialty microstructured optical fiber (MOF). A suspended tri-core MOF was fabricated using the stack and draw technique. A low finesse sensing head was prepared by depositing a chitosan polymer matrix within the holes of the MOF, forming a Fabry-Pérot interferometer as a sensing platform while the chitosan film acts as the sensing material. The use of the probe for real-time breath monitoring was also successfully demonstrated. The probe possessed a maximum sensitivity of 81.05 pm/(%RH) for 90–95%RH range while the linear region of the sensor ranged from 70–95%RH. The temperature cross correlation was also experimented, and a lower influence of external temperature was observed. The probe shows an ultrafast response during human breath monitoring with a rising time and recovery time of 80 ms and 70 ms, respectively.
关键词： humidity sensing,chitosan polymeric matrix,breath monitoring,microstructured optical fiber,Fabry–Pérot interferometer
更新于2025-09-19 17:13:59
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Temperature responsive self-assembled hydroxybutyl chitosan nanohydrogel based on homogeneous reaction for smart window
摘要： Chitosan (CS) based self-assembled nanohydrogels are considered as promising platform for biomedicine, petrochemical, agricultural and food applications due to their unique biodegradability, nano-interface effect, and intelligent responsiveness. However, the most CS derivatives are prepared in heterogeneous system, which is unstable and environmentally unfriendly. In this work, a series of hydroxybutyl chitosan (HBC) was synthesized based on a green and homogeneous system (potassium hydroxide (KOH)/urea), which given this derivative interesting temperature responsive phase transformation behavior. HBC could change from dissolved state into nanohydrogel state in deionized water, when the temperature exceed its critical phase change temperature, and this process could be repeated more than 50 cycles (one cycle/day) without coagulation. The nanohydrogels solution exhibited concentration and temperature-dependent ultraviolet absorption and visible light regulation, which had great application potential in smart windows. This study provided a novel preparation method and extended the application of chitosan-based temperature responsive self-assembled nanohydrogels.
关键词： Temperature responsiveness,Thermochromism,Hydroxybutyl chitosan,Self-assembled nanohydrogels,Smart windows,Homogeneous reaction
更新于2025-09-16 10:30:52
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Hydrogel-embedded gold nanorods activated by plasmonic photothermy with potent antimicrobial activity
摘要： Plasmonic photothermal therapy (PPTT) has been used as an alternative to chemotherapy for the elimination of resistant microorganisms; however, its in situ evaluation has not been well studied. In the present study, we assessed the antimicrobial activity of a chitosan-based hydrogel embedded with gold nanorods (Ch/AuNRs) using a low power infrared diode laser. The antibacterial activity was measured in both Gram-positive and –negative strains, including clinical isolates of multidrug-resistant pathogens. The cytotoxic effect, cellular proliferation, and the expression of the pro-inflammatory (IL-6 and TNF-α) and anti-inflammatory (IL-10) cytokines were quantified in a murine model of macrophages. Results showed a potent antimicrobial activity of the Ch/AuNRs with MICs ≤4 μg/mL, very low cytotoxicity with cell viability above 80%, and the macrophage proliferation was not affected for a period of 48 h. These results suggest that our Ch/AuNR-embedded hydrogel could be an option to locally control chronic nosocomial infections using PPTT.
关键词： inflammation,multidrug resistant,antifungal,photothermal therapy,gold nanorod,cytotoxicity,chitosan,antibacterial
更新于2025-09-16 10:30:52
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Development of a Hybrid Chitosan- and Niacinamide-Coupled ZnO Nanoparticle Composite for Sun Protection Application
摘要： Zinc oxide nanoparticles (ZnO) have long been utilized as UV-protective sunscreen components due to their high durability and lower skin irritation while maintaining capability for blocking UV rays. However, the dispersal and transparency properties of ZnO need to be enhanced in order to improve the capacity for creating effective sunscreen through control of the physiochemical properties of ZnO. In this study, chitosan or niacinamide, which are suitable functional cosmetic compounds and effective skin lightening agents, are combined with ZnO for the development of better UV-protective products. Each biocompatible coating material is individually attached on its surface after the synthesis of ZnO. The size is 70 nm using the sol-gel method. Their morphology and chemical structure are characterized by FT-IR, XRD, SEM, TEM, TGA, and zeta potential. The results indicate that approximately 50% of chitosan and 5% niacinamide were coated on the ZnO. To confirm the capacity of each surface-coated ZnO with chitosan and niacinamide as a sunscreen, we measured their transmission, reflectance, and sun protection factor (SPF) using a UV spectrophotometer and SPF. As a result, the niacinamide-coated ZnO shows remarkably lower transmission and high reflectance against UV rays than that of bare ZnO and chitosan-coated ZnO. Furthermore, niacinamide-coated ZnO exhibits great lightening effects. Consequently, these results demonstrate that niacinamide coating is highly effective for the production of sunscreen emulsions.
关键词： Zinc oxide nanoparticles,TEM,FT-IR,SEM,XRD,UV-protective sunscreen,TGA,chitosan,SPF,sol-gel method,zeta potential,niacinamide,sun protection factor
更新于2025-09-12 10:27:22
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Ethanol-Precipitation-Assisted Highly Efficient Synthesis of Nitrogen-Doped Carbon Quantum Dots from Chitosan
摘要： Nitrogen-doped carbon quantum dots (NCQDs) were prepared from chitosan through a hydrothermal reaction. When ethanol precipitation was used as the puri?cation method, a high product yield of 85.3% was obtained. A strong blue ?uorescence emission with a high quantum yield (QY) of 6.6% was observed from the NCQD aqueous solution. Physical and chemical characteristics of the NCQDs were carefully investigated by transmission electron microscopy (TEM), X-ray di?raction (XRD), Fourier transform infrared spectra (FTIR), Raman spectra, X-ray photoelectron spectroscopy (XPS), and transient ?uorescence spectra. Experimental results showed that diameters of the NCQDs were in the range of 2?10 nm. The carbon quantum dots possess good water dispersibility and precipitation by ethanol. When used for metal ion detection, the detection limit of the NCQDs for Fe3+ was as low as 1.57 μM. This work proposed a facile method to synthesize NCQDs from chitosan with high yield and demonstrated that carbon quantum dots derived from chitosan were promising for ion detection.
关键词： ethanol precipitation,metal ion detection,chitosan,hydrothermal reaction,Nitrogen-doped carbon quantum dots
更新于2025-09-12 10:27:22
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Development of Plasmonic Chitosan-Squarate Hydrogels via Bio-Inspired Nanoparticle Growth
摘要： We report on the bio-inspired growth of gold nanoparticles (GNPs) in biocompatible hydrogels to develop plasmonic hybrid materials. The new hydrogel (CS-Sq) is prepared from chitosan and diethylsquarate and is formed via non-covalent interactions rising between the in-situ formed ionic squaric acid derivatives and chitosan. Interestingly, when the hydrogel is prepared in the presence of HAuCl4, GNPs with controlled sizes between 15 and 50 nm are obtained which are homogeneously distributed within the plasmonic hydrogels (GNPs-CS-Sq). We found that the supramolecular nature and the composition of the CS-Sq hydrogels are key for the GNPs growth process where the squaric derivatives act as reducing agents and the chitosan hydrogel network provides nucleation points and supports the GNPs. Accordingly, the hydrogel acts as a bio-inspired reactor and permits to gain certain control on the GNPs size by adjusting the concentration of chitosan and HAuCl4. Besides the intrinsic and tunable plasmonic properties of the GNPs-CS-Sq hydrogels, it was found that the gels could be useful as heterogeneous catalysts for organic reactions. Furthermore, cell viability studies indicate that the new hydrogels exhibit suitable biocompatibility. Thus, the proposed method for obtaining GNPs-CS-Sq hydrogels has the potential to be applied for the development of a wide variety of other hybrid chitosan materials useful for catalysis, biosensing, cell culture, tissue engineering, and drug delivery applications.
关键词： Chitosan,Hybrid Materials,Hydrogels,Squaric Acid,Gold Nanoparticles
更新于2025-09-12 10:27:22