Biomaterials Science
·
2020
·Vol. 8
·期 6
·1695-1701
·
IF 6.183
Yu Zhang,Liming Li,Jiafu Mu,Jiachen Chen,Shiqing Feng,Jianqing Gao
Spinal cord injury is one of the most serious traumatic diseases. The current available clinical therapies are unable to provide effective recovery of nerve functions. Implantation of biomaterial scaffolds is a promising approach to bridge the damaged nerve tissue in the absence of the extracellular matrix. However, the treatments have been impaired by the increased generation of reactive oxygen species in the microenvironment of acute spinal cord injury. Efficient delivery of antioxidants and biocompatible materials and reagents has been a challenge. Herein, a novel hyaluronic acid (HA) hydrogel functionalized with the antioxidant compound 2,2,6,6-tetramethylpiperidinyloxy (TEMPO) is fabricated for nerve tissue regeneration after serious spinal cord transection in rats. TEMPO is tethered onto HA chains to form HA-TEMPO through a Schiff base reaction between 4-amino-TEMPO and aldehyde modified HA chains. The TEMPO-hydrogel is constructed with a highly porous three-dimensional structure via the gelation between the residue aldehydes in HA-TEMPO and the amines in adipic dihydrazide modified HA. The functional TEMPO-hydrogel exhibits the antioxidant effect in an H2O2 simulated in vitro peroxidative microenvironment. Implantation of the functional hydrogel in vivo induces a significant motor function restoration, which could be attributed to the effective functions of the TEMPO-hydrogel in tissue reconnection as well as nerve fiber regeneration of the central nervous spinal cord tissue. Importantly, the treatment with the TEMPO-hydrogel effectively protects the bladder tissue from neurogenic damage. Therefore, the functional TEMPO-hydrogel provides a promising strategy for the treatment of central nervous system diseases through the antioxidant and lesion-bridging regulation of the pathological microenvironment.
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FIBERS AND POLYMERS
·
2020
·Vol. 21
·期 6
·1251-1258
·
IF 1.797
Liang Huazhe,Cao Meng,Yang Desheng,Sun Tingting,Chu Xiaomeng,Liu Shaojie
A series of polyamidoamine (PAMAM) immobilized TEMPO macromolecular catalysts were prepared by condensation reduction reactions between carbonyl groups in 4-O-TEMPO and primary amines in PAMAM. The macromolecular catalyst and NaBr/NaClO were used as catalytic system for selective oxidation of cellulose in aqueous medium. Effects of various factors, such as TEMPO loading ratios and PAMAM generations, were studied on the catalytic performances. Compared with free TEMPO, the macromolecular catalyst with less than 50 % TEMPO loading ratio had a higher reaction rate in the initial stage of the reaction. Especially, the reaction rate of G1.0 PAMAM with 30 % TEMPO loading ratio was comparable to free TEMPO in the whole reaction process. Its cellulose oxidation degree (or catalytic activity) was also equivalent to the level of free TEMPO. Interestingly, the cellulose depolymerization degree of macromolecular catalyst was not affected by the cellulose oxidation degree and was lower than that of free TEMPO. The macromolecular catalyst could be recycled efficiently by the combination of supernatant circulation and salting-out extraction, and the recycling performance was excellent.
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INDUSTRIAL CROPS AND PRODUCTS
·
2024
·
IF 5.6
Lin Li,Runkai Wang,Jiangyan Ji,Tong Wu,Dongdong Liu,Xinjian Hu,Fei Chai
This study presents an efficient extraction of nanocellulose crystals (CNCs) and nanofibers (CNFs) through ultrasound-assisted TEMPO oxidation method using deep-processed heavy metal-containing calabash as raw material. The extraction method, integrating TEMPO-mediated oxidation and ultrasound techniques, enhanced the yield of CNCs and CNFs. The results demonstrate that CNCs yielded 63 %, with a carboxyl content of 1.27 mmol/g, while CNFs yielded 31 %, with a carboxyl content of 1.21 mmol/g. CNCs and CNFs exhibited excellent mechanical properties, with CNCs having an average length of 214.4 nm, average diameter of 2.72 nm, and a length-to-diameter ratio of 78.8. CNFs had an average length of 437.8 nm, average diameter of 5.7 nm, and a length-to-diameter ratio of 76.8. X-ray diffraction (XRD) results showed crystallinity of 87.1 % for CNCs and 81.2 % for CNFs. The thermal stability of the fibers was confirmed up to 230℃. The film prepared by combining 10 % PVA with 90 % CNC exhibited a tensile strength of 32.11 MPa, Young's modulus of 2027.1 MPa, and could generate a maximum voltage of 0.83 V. This study provides an effective pathway for the value-added utilization of deep-processed calabash and highlights the broad application prospects of the composite film in the field of flexible sensors.
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JOURNAL OF MATERIALS SCIENCE
·
2023
·Vol. 59
·期 2
·563-576
·
IF 4.5
Cao Shuangquan,Chen Jisi,Yang Quanling,Xiong Chuanxi,Fan Rong,Shi Zhuqun
Lithium-sulfur (Li–S) batteries have received great attention due to their high theoretical specific capacity and energy density, wide range of sulfur sources, and environmental compatibility. However, the development of Li–S batteries is limited by a series of problems such as the non-conductivity and volume expansion of the sulfur cathode and the shuttle of lithium polysulfide. It is frequently feasible to alleviate these difficulties by blending carbon-based conductive additives with the cathode material, utilizing a nanostructured cathode, or enhancing the cathode's flexibility. Here, an ion/electron dual-conductive three-dimensional (3D) network structure has been constructed using TEMPO-oxidized cellulose nanofibrils (OCNF) and modified carbon nanotubes. We improved the ionic/electronic conductivity of the cathode materials by adding NCNT or SCNT, and also boosted its electrochemical performance through effective inhibition of polysulfide shuttling by amino or sulfonic acid groups that adsorb the polysulfide. The results showed that the 40-CNFSC@S composite cathode with the introduction of sulfonated carbon nanotubes (SCNT) contained up to 73.9 wt% of sulfur and exhibited the best electrochemical performance, with an initial specific capacity of 1052 mAh g −1 at 0.5 C, and the specific capacity was still as high as 837 mAh g −1 after 120 cycles. Its great cycling stability allows for environmentally friendly and low-cost cellulose-based materials to be utilized in Li–S batteries.
研究领域:
储能
·
材料科学
·
纳米技术
·
电化学
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INTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES
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2022
·
IF 8.025
Hanyu Wang,Yehong Chen,Padonou-Kengue Patrick Dorsel,Chaojun Wu
In this study, carbon dots (CDs) were prepared by a one-pot hydrothermal method using tempo-oxidized cellulose nanocrystals (TOCNC) and polyethylenimine (PEI). The CDs were self-assembled with a microsphere adsorbent prepared using TOCNC and sodium alginate (SA). CDs-TOCNC/SA—an environmentally friendly, fluorescent-sensitive, and recyclable microsphere adsorbent—was obtained. FTIR analysis showed that PEI successfully modified the CDs. In addition, the fluorescence quenching of CDs was observed when the concentration of Pb 2+ was 0.0001–100 mg/L, indicating that CDs can dynamically monitor Pb 2+ . CDs-TOCNC/SA can produce blue fluorescence under 365 nm UV light and selectively and efficiently adsorb Pb 2+ . When the concentration of Pb 2+ was 0.0001–100 mg/L, fluorescence quenching of the adsorbent was observed, indicating that CDs-TOCNC/SA could visually adsorb Pb 2+ . The adsorption isotherm and kinetic parameters show that the adsorption process conforms to the Langmuir isotherm model at 298 K, and the maximum adsorption capacity of Pb 2+ was 190.1 mg/g at pH = 5. Moreover, CDs-TOCNC/SA could still obtain 78.99 % Pb 2+ after five sorption-desorption cycles. The adsorption mechanism may involve ion exchange, electrostatic attraction, intra-particle diffusion, and chemical complexation.
研究领域:
环境科学
·
材料科学
·
分析化学
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JOURNAL OF CHEMICAL RESEARCH
·
2020
·
IF 0.593
Zhenzhen Geng,Hong-yu Zhang,Guohui Yin,Yuecheng Zhang,Jiquan Zhao
The ionic liquid 1-methyl-3-(3-sulfopropyl)imidazolium chloride ([MIMPs]+Cl-) in combination with 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) and sodium nitrite (NaNO2) as a catalytic system demonstrates high efficiency in the one-pot two-step aerobic oxidative condensation of benzyl alcohols with 1,2-phenylenediamines to give benzimidazoles. Various benzimidazoles are obtained in good to excellent yields by this strategy.
研究领域:
有机化学
·
催化化学
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POLYMER DEGRADATION AND STABILITY
·
2026
·
IF 8.1
Yansong Liu,Dingding Zhang,Yiting Tong,Zenan Chi,Xi Yu,Wei Tan,Zengge Guo,Yuanlin Ren
Improving the flame retardancy of Lyocell fibers without compromising their mechanical properties is the key to expanding their high-end applications. To achieve this goal, an innovative phosphorus-free flame-retardant modification strategy of "crosslinking protection first and then directional oxidation" was proposed. Melamine-crosslinked Lyocell fibers (MC@Lyocell) were constructed through the treatment of hydroxymethylated melamine, which were then directionally oxidized by a 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) mediated NaClO oxidation system to in-situ generate sodium carboxylate (-COO - Na⁺) groups of cellulose fibers to obtain high flame-retardant oxidized MC@Lyocell fibers (OMC@Lyocell). The modified fibers exhibited significantly enhanced flame retardancy: Limiting oxygen index (LOI) increased from 17.0% to 30.5%, the peak heat release rate (PHRR) and total heat release (THR) decreased by 79.6% and 50%, respectively. Meanwhile, the structural integrity and mechanical properties were well maintained. Compared with the original fibers, the crystallinity only slightly decreased by 8%∼15%, with slower mass loss and a decline of polymerization degree. The melamine crosslinked network confines oxidation to cellulose crystal surfaces and amorphous regions, resolving the contradiction between carboxyl generation and mechanical property decrease. This environmentally friendly and efficient phosphorus-free strategy provides a new direction for preparing high-performance, structurally stable flame-retardant cellulose fibers.
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ACTA PHYSICO-CHIMICA SINICA
·
2017
·Vol. 33
·期 7
·1390-1398
·
IF 0.767
YIN Lu,LIANG Cheng,CHEN Ke-Xian,ZHAO Chen-Xuan,YAO Jia,Li Hao-Ran
A novel Pt(II)-based metallointercalator terpyridine complex linked with a 2,2,6,6-tetramethyl-1-piperidinyl N-oxide (TEMPO) derivative was prepared by a reaction between 4'-TEMPO-terpyridine (L) and a Pt(II) salt. This complex presented unusual luminescence quenching owing to
the effect of the stable nitroxide radical. The crystal structure of[Pt(terpy-TEMPO)Cl]Cl·H2O·CH3OH (terpy=2,2':6',2"-terpyridine) was elucidated by X-ray crystallography. Additionally, the effect of TEMPO on the photophysical properties of[Pt(terpy-TEMPO)Cl]
Cl·H2O·CH3OH was investigated by UV-Vis, fluorescence emission, and electron paramagnetic resonance (EPR) spectroscopy. Data from the absorption and luminescence properties (298 K) of the[Pt(terpy-TEMPO)Cl]+ complex indicated the presence of two
groups of typical bands:an intense band B with distinct vibronic structures (270-350 nm, ε>104 dm3·mol-1·cm-1) and a less intense band A (370-450 nm, ε~103 dm3·mol-1·cm-1).
These two bands are generally assigned to ligand-to-ligand charge transfer (LLCT) and metal-to-ligand charge transfer (MLCT) excited states, respectively. Furthermore, efficient photoluminescent quenching behavior was observed in the emission spectra of this complex system. Quantum calculations
of the molecular energy gaps and bands were performed by Gaussian 09 software. The calculated results verified that TEMPO greatly affects the energy gaps between the highest occupied molecular orbital and the lowest unoccupied molecular orbital. Thus, the relationship between efficient photoquenching
and molecular structure was theoretically interpreted. EPR results indicated that when TEMPO is attached to a macrocyclic terpyridine platinum complex, e.g.,[Pt(terpy)Cl]+, the terpyridine platinum complex does not affect the hyperfine coupling constant (A value) and g
factor (g values) but the rotation and relaxation times of the TEMPO radical.
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INTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES
·
2024
·
IF 7.7
Dongmei Li,En-Jie Li,Li Li,Bo Li,Shiru Jia,Yanyan Xie,Cheng Zhong
Pure gelatin film often exhibits high hydrophilicity and a lack of antibacterial activity, hindering its practical application in the field of food preservation. To address these issues, we incorporated 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO)-oxidized bacterial cellulose (TOBC) nanofibers stabilized cinnamon essential oil (CEO) Pickering emulsions into the gelatin matrix to develop active food packaging films. The study revealed that the good distribution of emulsion droplets in the film matrix. While with increasing Pickering emulsion proportion, the microstructures of composite films were more heterogeneous, showing some pores or cavities. In addition, the insertion of TOBC-stabilized CEO emulsions could improve the elongation at break (EAB), water-resistance, UV blocking ability, and antibacterial activity of film, but reduced its tensile strength (TS) and water vapor barrier properties (WVP). Notably, the film prepared with 4 % TOBC-stabilized CEO Pickering emulsion demonstrated enhanced preservation of strawberries. Overall, the as-prepared gelatin-based active composite films have considerable potential for food packaging.
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SPECTROCHIMICA ACTA PART A-MOLECULAR AND BIOMOLECULAR SPECTROSCOPY
·
2022
·
IF 4.831
Meng Wang,Jiao Wang,Nan Ma,Shuaibing Yu,Jinming Kong,Xueji Zhang
In this work, a new colorimetric method for the determination of Glutathione (GSH) on the basis of stable free radical 2,2,6,6 − tetramethylpiperidine − 1 − oxyl (TEMPO) oxidation of 3,3′,5,5′−tetramethylbenzizine (TMB) via copper(II) acetylacetonate (Cu(acac) 2 ) catalysis was proposed. TEMPO was catalyzed by Cu(acac) 2 to produce TEMPO + , then TEMPO + oxidized TMB to produce oxidized TMB (ox − TMB). The resulting ox − TMB showed blue and possessed a distinct absorption peak about 650 nm. Whereas, GSH prohibited the generation of ox − TMB through inhibiting TMB oxidation. As compared to the case that GSH was absent, significantly enhanced absorption was determined, and was proportional to GSH amount. On this basis, a qualitative and quantitative detection method of GSH with the naked eye and the microplate reader was achieved. The developed TEMPO − based method achieved GSH biosensing with improved sensitivity in a good specificity − manner. The limit of detection (LOD) was 90 μM via naked eye, and the microplate reader was 4.71 μM. And the stable free radical TEMPO possessed higher stability and lower toxicity than traditional oxidant of H 2 O 2 . Moreover, this TEMPO − based method achieved good results in the detection of GSH in human serums.
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INTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES
·
2024
·
IF 7.7
Lei Dai,Yijiao Xue,Sihan Tian,Ping He,Pan Xie,Zhu Long,Guiqiang Fei,Zhirong Chen
The monitoring of foodborne bacterial contamination requires simple and convenient biosensors . This work describes a novel paper-based colorimetric biosensor for the rapid and sensitive bacteria detection. The biosensor was constructed via the encapsulation of D-alanyl-D-alanine capped gold nanoparticles (DADA-AuNPs) in a modified paper that was fabricated by the freeze-drying of TEMPO-oxidized cellulose nanofibers/cationic guar gum composite hydrogel-modified filter paper. The results indicated that the size of DADA-AuNPs largely determined the color of their aqueous system and they exhibited light red to dark red as their size increased from around 6 to 36 nm. All these different sized DADA-AuNPs turned into colorless when encountered with either S. aureus or E. coli . In particular, the smaller the DADA-AuNPs size, the faster the discoloration. The encapsulation of DADA-AuNPs into modified paper negligibly changed their responsiveness towards bacteria. In comparison to the original filter paper and oven-dried hydrogel-modified filter paper, the freeze-dried hydrogel-modified paper was demonstrated to be a better substrate for the encapsulation of DADA-AuNPs since they could be loaded with a larger amount of DADA-AuNPs in a faster way and showed a better perceivable color. This work demonstrated a promising paper-based colorimetric biosensor for the facile and rapid detection of bacteria.
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INTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES
·
2023
·
IF 8.2
Yuxuan Ren,Zhe Ling,Caoxing Huang,Chenhuan Lai,Qiang Yong
Anti-ultraviolet material with cost-effectiveness, environmental friendliness, and multifunction is urgently needed to address the serious problem of ultraviolet radiation . However, traditional anti-ultraviolet products based on plastics are unsustainable and harmful to the environment. Herein, the cellulose films with a sandwich structure using a surface assembly technique were reported. Natural L -phenylalanine was grafted onto cellulose nanofibrils via amidation to enhance their UV-shielding property. To address the hydrophilic nature and limited mechanical strength of cellulose films, we employed octadecyltrichlorosilane and 4ARM-PEG-NH 2 for hydrophobic coating and mechanical reinforcement, respectively. In addition to providing complete UV resistance in the wavelength range of 200–320 nm, sample OPT5 exhibited significantly improved tensile stress, Young's modulus , and toughness, measuring 174.09 MPa, 71.11 MPa, and 295.33 MJ/m 3 , respectively. Furthermore, due to the presence of antibacterial amine groups, the modified film demonstrated a satisfactory inhibitory effect on the growth of Escherichia coli and Bacillus subtilis . Compared to natural cellulose films, the hydrophobically modified material achieved a contact angle of up to 121.1°, which enabled efficient separation of oil-water mixtures with a maximum separation efficiency of 93.87 %. In summary, the proposed TOCNF-based UV-shielding film with multifunctionality holds great potential for replacing petrochemical-derived plastics and serving as an applicable and sustainable membrane material.
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