Single-Component Photochemical Afterglow Near-Infrared Luminescent Nano-Photosensitizers: Bioimaging and Photodynamic Therapy.

Long afterglow luminescence-guided photodynamic therapy (PDT) performs advantages of noninvasiveness, spatiotemporal controllability, and higher signal to noise ratio. Photochemical afterglow (PCA) system emitting afterglow in an aqueous environment is highly suitable for biomedical applications, but still faces the challenges of poor tissue penetration depth and responsive sensitivity. In this work, two novel compounds, Iso-TPA and ABEI-TPA, are designed and synthesized to integrate the PCA system as a single component by coupling near-infrared (NIR) photosensitizers with singlet oxygen cache units, respectively. Both compounds emit NIR afterglow based on photochemical reaction. ABEI-TPA exhibits higher photoluminescence quantum efficiency with nonconjugated linkage, while Iso-TPA with conjugated linkage possesses better reactive oxygen species generation efficiency to achieve stronger PCA and effective PDT, which is ascribed to stronger intramolecular charge transfer effect of Iso-TPA. Iso-TPA nanoparticles can achieve effective long-lasting NIR afterglow in vivo bioimaging up to 120 s with higher imaging resolution and outstanding PDT efficacy of tumor, exhibiting promising potential on bioimaging and therapy.

Potassium 2-thienyl tri-fluoroborate as a functional electrolyte additive enables stable interfaces for Li/LiFe0.3Mn0.7PO4batteries.

As a promising cathode material for high-performance lithium-ion batteries, olivine LiFe1-xMnxPO4 (0 < x < 1, LFMP) combines the high safety of LiFePO4 and the high energy density of LiMnPO4. During the charge-discharge process, poor interface stability of active materials leads to capacity decay, which prevents its commercial application. Here, to stabilize the interface, a new electrolyte additive potassium 2-thienyl tri-fluoroborate (2-TFBP) is developed to boost the performance of LiFe0.3Mn0.7PO4 at 4.5 V vs. Li/Li+. Specifically, after 200 cycles, the capacity retention remains at 83.78% in the electrolyte containing 0.2% 2-TFBP while the capacity retention without 2-TFBP addition is only 53.94%. Based on the comprehensive measurements results, the improved cyclic performance is attributed to that 2-TFBP has a higher highest occupied molecular orbit (HOMO) energy and its thiophene group can be electropolymerized above 4.4 V vs. Li/Li+ for generating uniform cathode electrolyte interphase (CEI) with poly-thiophene, which can stable materials structure and suppress the decomposition of electrolytes. Meanwhile, 2-TFBP both promotes the deposition/exfoliation of Li+ at anode-electrolyte interfaces and regulates Li deposition by K+ cations through the electrostatic mechanism. This work presents that 2-TFBP has a great application prospect as a functional additive for high-voltage and high-energy-density lithium metal batteries.

Intelligent hydrogel with both redox and thermo-response based on cellulose nanofiber for controlled drug delivery.

The purpose of this study is to develop a hydrogel with temperature and redox response to control drug delivery. However, the strength of temperature sensitive N-isopropylacrylamide (NIPAM) hydrogel is weak. Therefore, 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) oxidized cellulose nanofiber (CNF) is introduced to improve this problem. The compressive strength of hydrogels increased by 360% after CNF addition. Meanwhile, N,N'-bis(acryloyl)cystamine (BACy) is introduced into the hydrogels as a cross-linker, imparting redox responsive properties to the hydrogels. Tumor therapeutic drugs are used as model drugs for in vitro release studies. The drug release rate of hydrogel is regulated by temperature and reducing environment. The maximum cumulative release rate of doxorubicin (DOX) is 39.56%, and the Berberine (BBR) is 99.50% after 60 h. The swelling and transparency of hydrogels showed dramatic changes in the range of 30-40 °C. Cytotoxicity experiments demonstrated that the hydrogel had almost no cytotoxicity.

Transparent oxygen barrier nanocellulose composite films with a sandwich structure.

Transparent gas barrier materials have extensive applications in packaging, pharmaceutical preservation, and electronics. Herein, we designed transparent films with a symmetric sandwich structure using layer-by-layer assembly of biaxially oriented polypropylene (BOPP) and acrylic resin (AR) followed by a cellulose nanoparticle (CNP) layer. The BOPP as a substrate created a barrier to hinder the transmission of water molecules to the adhesive AR layer and gas barrier functional CNP layer. The aspect ratio of the CNPs was shown to affect the film microstructure, resulting in different values for the oxygen transmission rate (OTR). The well-organized CNP layer exhibited lower OTR when compared with the network layer. The thickness, density, and porosity of the CNP layer exhibited correlations with OTR. The water molecules were able to flow in through an additional pathway, thus increasing the water vapor transmission rate (WVTR). Moreover, these sandwiched cellulose composite films showed excellent light transmittance and tensile strength.

Microbial dyes: dyeing of poplar veneer with melanin secreted by Lasiodiplodia theobromae isolated from wood.

Dyeing methods that conform to environmental protection requirements and adapt to the development of industry are investigated using bleached poplar wood dyed with melanin secreted by Lasiodiplodia theobromae in this paper. Prolonging the dyeing time of coarse melanin can improve the dye uptake of veneers, and the brightness value increases, and the reflectivity declines with the increase of dyeing time. The stained surface of the vessel is gradually covered by coarse melanin dye, and more melanin particles can be clearly observed accumulating together on the stained surface with agar. Infrared measurements show that the absorption peak of -C=O in carboxylic acid disappears at 1740 cm-1, which can be attributed to the fact that -C=O (1776 cm-1) in an anhydride or ketone group is formed by further oxidation and condensation of agar and NaOH. The veneer dyed for 6 h showed a well light and water resistance. Additionally, dyeing can improve the wettability of water, phenolic resin, and urea formaldehyde resin on the surface of veneer. These results support the use of pigment secreted by stain fungi for wood and provide data for evaluating their use as sustainable materials for other applications.

Coupling chitosan and TEMPO-oxidized nanofibrilliated cellulose by electrostatic attraction and chemical reaction.

This study reports coupling methods of chitosan (CTS) and TEMPO-oxidized nanofibrilliated cellulose (TONCs). Coupling chitosan, a cationic polysaccharide, to anionic TONCs is preformed through physical crosslinking via ionic bond formation at room temperature and carefully controlled pH and mass ratio. After heating, the carboxyl group of TONCs and the ammonium group of chitosan react into an amide covalent bond linkage CONH. Fourier Transform infrared spectroscopy, 13C solid-state nuclear magnetic resonance, are used to confirm the bonds. Films of the modified TONC are produced by casting and exchanging method and atomic force microscopy and thermogravimetric analysis was used to study the film properties. Further, the tensile strength of the CTS-TONCs films is improved for the covalent bond produced indicating a straight forward method to augment the properties of these all-polysaccharide films.

Synthesis and characterization of chitosan based dye containing quaternary ammonium group.

A new antimicrobial biopolymer dye was synthesized by reaction of quaternary ammonium salt of chitosan and reactive red x-3b. And quaternary ammonium salt of chitosan was produced by grafting glycidyltrimethylammonium chloride on chitosan. The synthesized materials were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), solubility test and antimicrobial test. Results show that the antimicrobial biopolymer dye was combined by N(+)(CH3)3 of quaternary ammonium salt of chitosan and sulfonic group of reactive red x-3b. Water solubility of chitosan biopolymer dye was increased as well as pH value. In addition, antibacterial property of new synthesized dye was excellent, whose antibacterial rates of Staphylococcus and Escherichia coli were both bigger than 99%. These results may provide new perspectives on improving the decorative properties and antimicrobial properties in wood industry.

Preparation of a Novel Chitosan Based Biopolymer Dye and Application in Wood Dyeing.

A novel chitosan-based biopolymer dye possessing antibacterial properties was synthesized by reaction of O-carboxymethyl chitosan and Acid Red GR. The synthesized materials were characterized by Fourier transform infrared spectroscopy (FTIR), degree of substitution (DS), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TG), X-ray diffraction (XRD), water solubility test, antibacterial property test, and dyeing performance, including dye uptake, color difference, and fastness. Results showed that the synthesized dye was combined by ⁻NH3⁺ of O-carboxymethyl chitosan and the sulfonic group of Acid Red GR. According to the comprehensive analysis of XRD and water solubility, the introduction of the carboxymethyl group and acid dye molecule changed the structure of the chitosan from compact to loose, which improved the synthesized dye's water solubility. However, the thermal stability of the synthesized dye was decreased. The antibacterial property of the poplar wood dyed with the synthesized dye was enhanced and its antibacterial rate, specifically against Staphylococcus aureus and Escherichia coli, also increased to a rate of more than 99%. However, the dye uptake of the synthesized dye was lower than that of the original dye. Despite this, though, the dyeing effect of the synthesized dye demonstrated better water-fastness, and light-fastness than the original dye. Therefore, the novel chitosan-based biopolymer dye can be a promising product for wood dyeing.