Applied Materials Today
·
2019
·
IF 8.013
Ozioma Udochukwu Akakuru,M. Zubair Iqbal,Chuang Liu,Jie Xing,Zhenni Wei,Zhenqi Jiang,Qianlan Fang,Bo Yuan,Elvis Ikechukwu Nosike,Jianbi Xia,Yinhua Jin,Jianjun Zheng,Aiguo Wu
Magnetic resonance imaging (MRI) signal intensities in tissues are usually enhanced by the injection of metal-based contrast agents (CAs) in patients. Some of these metal compounds have been linked to incurable nephrogenic systemic fibrosis and other neurological disorders, leading to their discontinuation. Herein, we report the design, synthesis, and characterization of a self-assembled metal-free CA which is based on an organic nitroxide radical (4-carboxy-TEMPO) compartmentalized in the biocompatible, biodegradable natural polymer, chitosan (CS), alongside folate targeting for in vivo tumor MRI. This extension conceivably heralds a new application for CS-TEMPO, which hitherto was used in macro-sizes as initiators for grafting CS to various polymers. Significantly, the folic acid (FA)-modified metal-free CA (CS-TEMPO-FA; average size ∼113 nm) is substantially benign, with no evidence of acute toxicity; it exhibits desirable pharmacokinetic profile, enhanced stability in highly reducing environments, high nitroxide loading (molecular relaxivity ∼18.56 mM −1 s −1 ), and effective tumor targeting. This latter characteristic ameliorates the non-specific uptake of CAs by normal cells. CS-TEMPO-FA nanoparticles demonstrate commensurate contrast enhancement of the tumor region up to 1 h post-injection when injected into 4T1 tumor-bearing mice, a contrast enhancement capability hitherto unattained by TEMPO-based CAs. This work points to CS-TEMPO-FA as a potential alternative to metal-based CAs as well as an active folate-targeted metal-free CA for long-term longitudinal tumor MRI which ameliorates the otherwise short in vivo lifetimes of typical organic radicals-based CAs.
研究领域:
生物医学工程
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纳米技术
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材料科学
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医学成像
·
药学
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产品关联
DOI
高影响因子
IRANIAN POLYMER JOURNAL
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2016
·Vol. 25
·期 5
·465-474
·
IF 1.684
Zhang Heng,Gao Xin,Chen Ke-Li,Liu Qi-Xing
Parenchyma cellulose, isolated from bagasse pith BP, was utilized as an alternative resource for preparation of soluble cellouronic acid sodium salt (SCA) by selective oxidation with the catalytic amounts of 4-acetamide-TEMPO and NaClO, in which NaClO 2 was used as a primary oxidant in an aqueous condition. The yield and carboxyl content of SCA were measured as a function of NaClO 2 content, 4-acetamide-TEMPO loading, oxidation temperature, initial pH, and reaction time, and optimized by an orthogonal test with the objective of achieving a maximum yield with high carboxyl content. An optimal SCA yield of 71.0 % with 32.92 % carboxyl content was found under the conditions of NaClO 2 dosage of 16 mmol/g, 4-acetamide-TEMPO loading of 0.20 mmol/g, and oxidation temperature of 50 °C in acetate buffer at pH 5.5 for 72 h. The structure and morphology of both parenchyma cellulose and its oxidized product were further characterized by means of Fourier transform infrared spectroscopy (FTIR), X-ray photoelectronic spectroscopy (XPS), X-ray diffraction (XRD), and scanning electron microscopy (SEM). These techniques confirmed that parenchyma cellulose from bagasse pith was successively modified by an effective TEMPO-derivative-catalyzed oxidation process. The finding of this study might provide guidance in maximizing the yield of SCA from parenchyma cells utilizing the 4-acetamide-TEMPO/NaClO/NaClO 2 system. Considering the simple preparation process and favorable SCA property, this BP parenchyma cellulose showed unique characteristics with a great promise for high-valued modification and application in the areas of advanced and functional materials.
研究领域:
生物质转化
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高分子化学
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材料科学
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绿色化学
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纤维素化学
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功能材料
✓ 已验证
DOI
高影响因子
CARBOHYDRATE POLYMERS
·
2018
·
IF 5.158
Rong Tang,Jie Hao,Ruijie Zong,Fangxia Wu,Yangyang Zeng,Zhenqing Zhang
In this study, the TEMPO-mediated (TEMPO/NaBr/NaClO) oxidation pattern of curdlan was investigated through comprehensively structural analysis of the corresponding oxidized products. During the structural analysis, infrared spectroscopy (IR), nuclear magnetic resonance (NMR) spectroscopy, gel permeation chromatography tandem multiple angle laser scattering (GPC-MALS) and ultra-high performance liquid chromatography tandem quadrupole time of flight mass spectrometry (UHPLC-Q/TOF-MS) were applied. As a result, the homogenous β1-3 polyglucuronic acids (MW, 49.8, 29.8 and 7.0 kDa) were obtained with proper amount of oxidant (5.36 mmol NaClO) at various temperatures (4, 25, 50 °C), respectively. Compared to the oxidation of 1–4 linked glucan (starch and cellulose) with TEMPO-mediated system at same reaction conditions, higher degree of specific oxidation and less degradation were observed in that of 1–3 linked curdlan. The glycosylation at position 3 could stabilize the sugar ring, which inactivates the non-specific oxidation related hydroxyl groups on the sugar ring. Thus, the TEMPO-mediated system has higher selectivity to oxidize the primary hydroxyl groups of 1–3 linked curdlan and form polyglucuronic acid than those observed in the oxidation of starch and cellulose. In addition, same as those observed in previous work about starch, higher the temperature was used in the oxidation with TEMPO system, higher the activity of oxidant (NaClO solution) was, more non-specific oxidation occurred, and more the degradation were observed.
研究领域:
生物化学
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材料科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
JOURNAL OF FOOD ENGINEERING
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2020
·
IF 4.499
Ying Ji
The combination of 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)-oxidization and annealing was applied to modify structural properties of corn starch in order to obtain starch polymer microgels. Microgels were characterized by X-ray diffraction, ATR-FTIR and thermogravimetry analysis (TGA). The effects of microgels on the uptake and release of lysozyme were also analyzed. The formation of oxidized microgels through the crosslinking between starch molecules and sodium trimetaphosphate was confirmed by X-ray diffraction. The ATR-FTIR analysis suggested that TEMPO-oxidation results in the formation of carboxyl groups. TGA data indicated that oxidized-annealed microgels had less thermal stability than oxidized microgels. Furthermore, the oxidized-annealed microgels had an improved capacity for uptake and release of lysozyme. At this stage of the exploration, microgels prepared from corn starches by annealing and oxidation is simple and efficient.
研究领域:
食品科学
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生物化学
✓ 已验证
产品关联
DOI
高影响因子
Polymers
·
2022
·Vol. 14
·期 3
·474
·
IF 4.967
Jing Liao,Huihua Huang
Nano chitin is a promising biocompatible material with wide applications. In this work, a fungal-derived nano chitin was prepared fromHericium erinaceusresidue via mineral/protein purification and subsequent TEMPO-mediated oxidation. The structure, dispersity, and gelation ability of the prepared fungal nano chitin were studied. The results showed that the average length and width of the prepared fungal nano chitin were 336.6 nm and 6.4 nm, respectively, and the aspect ratio exceeded 50:1. The nano chitin retained the basic structure of chitin, while the crystallization index was improved. In addition, the dispersity of the nano chitin in aqueous media was evaluated by the effective diameter, and the polydispersion index was mainly affected by pH and ionic strength. Under acetic acid “gas phase coagulation”, the prepared nano chitin dispersions with mass concentrations of 0.2, 0.4, 0.6, and 0.8% were converted into gels by enhanced hydrogen bond crosslinking between nano chitins.Keywords:nano chitin;TEMPO-mediated oxidation;dispersion stability;hydrogels
研究领域:
生物材料学
·
微生物学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
Advanced Science
·
2026
·
IF 14.1
Ziyu Ba,Hongyun Luo,Jie Cui,Juan Guan,Zhaoliang Guo,Robert O. Ritchie
The mechanical potential of natural fiber-based composites remains restricted by interfacial constraints, preventing them from robust structural applications. Here, an interface decoupling strategy based on selective TEMPO (2,2,6,6-tetramethylpiperidine-1-oxyl) oxidation is applied to enhance the mechanical properties of densified bamboo simultaneously with thermally-assisted structural densification. The resulting compact TEMPO-oxidized densified bamboo exhibits ultrahigh tensile strength of 661 MPa and toughness of 22 MJ m −3 , representing 5.5 times higher than natural bamboo. Fracture morphologies, characterized by extensive fibril pull-out and bridging that enhance energy dissipation, align with acoustic emission data revealing frequent, low-energy microdamage events and a continuous, non-catastrophic failure process. Specifically, TEMPO-induced carboxylation disrupts orderly hydrogen bonds and increases the relative contribution of van der Waals interactions at the molecular level, enabling stress dissipation through a network of weaker, more reversible intermolecular forces. This work demonstrates that hierarchical interface engineering offers a broadly applicable strategy to endow natural composites with toughness and strength far exceeding their original mechanical paradigm.
✓ 已验证
产品关联
DOI
PubMed
高影响因子
INTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES
·
2024
·
IF 7.7
Guochen Xia,Shixu Yu,Zezhou Yang,Jingyi Lian,Yimin Xie,Qinghua Feng
Natural wood has been highly valued for thousands of years due to its excellent strength, low density, and ease of processing. However, its poor water stability, which leads to swelling and deformation, limits its competitiveness. In response, we designed a reconstructed wood through a process involving pretreatment, TEMPO oxidation, lignin self-assembly, lignin melting, and densification. In this material, cellulose serves as the skeleton, while lignin with a phenylpropyl structure acts as both a filler and binder. The resulting wood exhibits outstanding water stability, with no changes after 60 days of water immersion and a water absorption rate as low as 8.32 %. This stability is achieved through the densification of lignin, which is enhanced by lignin melting and pressure during self-assembly. The reconstructed wood not only offers excellent water stability but also boasts superior UV resistance and thermal stability. Additionally, it can be hot-pressed into straws within a mold, providing better water stability and tensile strength compared to paper straws. This reconstructed wood, made from natural wood and corncob, is biodegradable and environmentally friendly, offering a new approach to wood water stability strategies.
研究领域:
材料科学
·
林业科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
TEXTILE RESEARCH JOURNAL
·
2018
·
IF 1.54
Xiang Yeping,Yu Jianyong,Liu Liu,Zhang Ruiyun,Qu Yongshuai,Jing Miaolei
In this study, we found an environmentally friendly system in the degumming of hemp fiber without using a strong acid and alkali. The chemo-enzymatic modification and degumming of hemp fiber used an acetic acid–sodium acetate buffer solution containing laccase, hemicellulase and 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO) under a mild condition (pH = 5, T = 50℃). Through comparing and analyzing the physical and chemical properties of fiber products under different treatments, we found the method involving treatment with TEMPO/laccase/hemicellulase not only greatly removed most of the gum attached on the surface of the raw hemp fiber, but also introduced surface-active aldehyde and carboxyl groups into the fiber. The performances of the hemp fibers with different treatments were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy and X-ray diffraction. We also found the product was finer, with a lower content of non-cellulosic components and it had better water uptake properties (moisture sorption and water retention value), which has potential application values in textile industries.
研究领域:
材料科学
·
生物技术
✓ 已验证
产品关联
DOI
高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2023
·
IF 15.1
Dingyuan Zheng,Zehuai Li,Wenrui Yao,Yuning Wang,Ce Sun,Haiyan Tan,Yanhua Zhang
Wood has garnered renewed interest due to its capacity to reduce carbon emissions when replacing non-renewable materials. Wood modification is often necessary because achieving optimal performance solely from the wood itself is challenging. Strategies for wood modification fall short of being genuinely sustainable and eco-friendly. In this context, a catalyst-free esterification method mediated by maleic anhydride (MA) is introduced for modifying wood. Notably, this approach aligns with principles of recycling, reuse, and reduction. A comprehensive comparison of MA-mediated wood esterification versus TEMPO-mediated wood oxidization highlights the effectiveness and superiorities of the MA esterification approach. Delignified wood esterified by MA (MA-DW) exhibits higher charge content (2.42 ± 0.24 vs. 0.53 ± 0.08 mmol/g), superior mass gain (18.4 ± 2.6 wt% vs. −15.92 ± 3.5 wt%), efficient recycling capability of the reaction medium (MA could be recycled five times, while TEMPO cannot be recycled), and integrity of the final products (retaining intact geometry vs. complete disintegration) compared to TEMPO-oxidized delignified wood (TEMPO-DW). Moreover, the MA-DW platform can serve in energy storage applications as an electrode or in sewage remediation applications as a catalyst. The esterification method mediated by MA provides an eco-friendly pathway for modifying wood, serving as a platform for creating diverse materials, potentially offering innovative concepts and insights for wood modification research.
研究领域:
材料科学
·
环境科学
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
Nuclear Science and Techniques
·
2018
·Vol. 29
·期 7
·1-8
·
IF 1.085
Bian Zhong-Xuan,Miao Xia-Ran,Lin Jin-You,Tian Feng,Bian Feng-Gang,Li Hui
Cellulose nanofibrils (CNFs) are a type of natural nanomaterials extracted from plants and animals that have expanding applications in numerous areas benefiting from their inherent properties of renewability, biodegradability, and sustainability. For energy consumption reduction, CNFs were extracted from raw jute fibers, which were not pretreated in a hot alkali or acid solution, by TEMPO-mediated oxidation. Synchrotron radiation wide-angle scattering was performed to realize the crystallization of the CNF crystallites; Fourier transform infrared spectroscopy, transmission electron microscopy, and field-emission scanning electron microscopy were used to characterize the changes in chemical groups and visualized morphology of CNFs. The simplified preparation and shortened cycle should further help the study of the structure–function relationship of jute CNFs subjected to chemical modification.
研究领域:
材料科学
·
植物学
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
Cell Reports Physical Science
·
2024
·
IF 7.9
Fukun Niu,Yu Rong,Yibo Zhang,Ru Song,Zhiwei Ye,Peifeng Zou,Chuanxi Xiong,Zhuqun Shi,Quanling Yang
For mid-to-low-end and disposable wireless transmission devices, paper-based low dielectric substrates are cost-effective and environmentally friendly compared to traditional petroleum-based plastics such as polyimides. In this work, we introduce (2,2,6,6-tetramethylpiperidin-1-yl)oxyl (TEMPO)-mediated oxidation technology into commercial copy paper to achieve in situ growth of zeolitic imidazolate framework (ZIF-67) while increasing porosity. Through impregnation technology, ethyl cellulose and h-BN are combined to improve the water resistance (water contact angle: 122°), thermal conductivity (in-plane thermal conductivity: 13.55 W m −1 K −1 ), and antibacterial properties of the paper. The dielectric permittivity of modified paper is about 3, which exhibits excellent potential as a substrate for centimeter wave patch antennas. After verification, our developed paper oxidation technology is reliable and effective for various cellulose-based papers. This paper provides a low-cost and low-energy approach for the construction of cellulose-based porous structures, which promote the development and application of green materials and alleviate the serious global problem of electronic waste pollution.
研究领域:
材料科学
·
环境科学
·
电子工程
✓ 已验证
产品关联
DOI
高影响因子
INDUSTRIAL CROPS AND PRODUCTS
·
2017
·
IF 3.181
Xue Yang,Fuyi Han,Chunxia Xu,Shuai Jiang,Liqian Huang,Lifang Liu,Zhaopeng Xia
The aim of this work is to improve the economic value of corn husk, and to make better use of corn husk nanocellulose (NC). Corn husk NC was extracted via acid hydrolysis, TEMPO oxidation and high intensity ultrasonication methods, which was named AH-NC, TO-NC and US-NC, respectively. The NC was carefully characterized by transmission electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, thermogravimetric analysis and particle size and zeta potential analyzer. The results showed the preparation methods didn’t change the main chemical structure of cellulose. The crystallographic form of the three kinds of NC still was cellulose I. However, the effects of preparation methods on the morphology and properties were obvious. Among the three kinds of NC, TO-NC had the largest aspect ratio, and the best dispersion stability in diameter, but very low thermal stability. The AH-NC exhibited the highest crystallinity and best thermal stability, but a small aspect ratio. US-NC possessed low crystallinity and poor dispersion stability.
研究领域:
材料科学
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）