Yanzhi Dong,Jiaojiao Wang,Ting Zhou,Jinbing Pan,Xu Wang,Shao-Kai Sun
Highly sensitive iron oxide nanoparticles with stable, safe and efficient surface functionalization, as potential substitutes for gadolinium-based contrast agents (GBCAs) with increasing biosafety concerns, exhibit great potential for high-performance magnetic resonance angiography (MRA). Herein, we developed ultrasmall catechol-PEG-anchored ferrite nanoparticles (PEG-UMFNPs) for highly sensitive MRA. The obtained nanoprobe has a high T1 relaxivity value (7.2 mM−1 s−1) due to its ultrasmall size and Mn doping. It has a suitable hydrodynamic size of 20 nm, which prevents rapid vascular extravasation and renal clearance and prolongs its blood circulation time. In vivo MRA at 3.0 T using the nanoprobe shows that the arteries and veins of rats, even blood vessels as small as 0.32 mm, are distinctly visible, and the contrast enhancement can last for at least 1 h. In addition, due to the outstanding contrast enhancement and long circulation time, the stenosis and recanalization process of the rat’s carotid artery can be continuously monitored with a single injection of the nanoprobe. Our study indicates that PEG-UMFNPs are outstanding MR imaging nanoprobes that can be used to diagnose vascular diseases without the biosafety issues of GBCAs.
Compared to petroleum-based plastics, paper-based materials are biodegradable and renewable, effectively easing resource overconsumption and environmental pollution issues. However, their poor water and oil repellency restricts applications in food packaging. Adding water and oil repellents can enhance paper's barrier properties, but traditional fluorine-containing coatings pose health risks like biotoxicity, accumulation, and migration, leading to global regulatory restrictions. Thus, developing green, biodegradable, bio-based water and oil repellent coatings is the future trend. In this study, taking advantage of the high reactivity of cyanuric chloride (TCT), a chitosan-derived coating (CHI-g-OA 2 ) with a double hydrophobic chain structure was successfully constructed. The formula for the preparation was optimized by the response surface method. This “molecular modification” strategy, which grafts hydrophobic oleyl alcohol chains onto chitosan molecular chains to successfully construct a hydrophobic barrier, effectively solves the problem where competitive hydrogen bonding disrupts the dense hydrogen bond network formed within and between chitosan molecules, leading to significant attenuation of barrier performance. It also achieves the synergistic improvement of the material's waterproof and oil-repellent properties while retaining the original oil and gas barrier function, which meets the standard for food packaging materials. In addition, the tensile strength of the coated paper has been increased, showing good mechanical and thermal stability.
Fang Jingting,Wang Xiuwu,Wang Jing,Han Yingying,Chen Tao
Using petroleum-based plastic materials poses many serious problems, including resource consumption and environmental pollution. Paper-based materials are good substitutes for plastic products because of their biodegradability, resource-richness, and recyclability. Paper’s poor water and oil resistance limits its wide application in food packaging. The use of water and oil repellents is an effective strategy to improve the barrier properties of paper. However, fluorine-containing oil repellents produce perfluorooctanoic acid/perfluorooctanesulfonyl compounds (PFOA/PFOS), which are hazardous to human beings and the environment, during the preparation and use of the repellents. Therefore, developing non-toxic, harmless, and biodegradable bio-based waterproof and oil-resistant coatings is the mainstream trend in the future. In this study, simple and environmentally friendly fluorine-free waterproof and oil-resistant coatings for food wrapping paper were developed by grafting oleyl alcohol onto chitosan using the ring-opening reaction of epichlorohydrin, and the reagents successfully adhered to the surface of the paper. The successful synthesis of waterproof and oil-resistant coatings was confirmed by nuclear magnetic resonance (NMR) and infrared (IR) analyses. The chitosan-based coatings (CHI-g-xOA, x = 1/8, 1/4, 1/2, 1) with different oleyl alcohol contents were prepared by the facile method. The obtained coated paper CHI-g-xOA-p ( x = 1/4) has not only excellent oil resistance (Kit rating value of 11 ± 1.0/12), which meets the food-grade oil-proof requirement, but also has excellent water resistance (Cobb 60 value of 11.86 ± 1.60 g/m 2 ). Compared with the uncoated paper, the tensile strength and water vapor transmission rate of the coated paper were significantly improved.
危险品化学品经营许可证（带存储）