Zhengxing Song,Jing Wang,Jing Wang,Jin Liu,Xinzhi Wang,Yao Wang,Abdur Raheem Aleem,Matt J. Kipper,Laurence A. Belfiore,Jianguo Tang
Nanoparticle drug delivery systems are designed to be biocompatible and to control the distribution of poorly soluble drugs. Fluorescent nanoparticle drug carriers have been designed to enable fluorescence tracking. While such particles enable tracking of the carrier, this tracking does not report the local drug concentration. In this article, we report new nanoparticle drug carriers with stable, high-intensity fluorescence that sensitively reports the loaded drug concentration. The dumbbell-shaped nanoparticles are synthesized by combining europium (Eu) complexes with hyaluronic acid. The Eu complexes are superior to organic fluorophores, providing a narrow emission peak, high fluorescence intensity, long fluorescence lifetime, and insensitivity to photobleaching. The hyaluronic acid compatibilizes the nanoparticles with aqueous environments, and provides biocompatibility. We demonstrate that these polysaccharide nano-dumbbell aggregates (PNDAs) can effectively load drugs through structural changes, and sense the amount of drug loaded through changes in fluorescence intensity, enabling precise tracking of drug loading and release.
It is of great significance to enhance the fire safety of epoxy resins (EP), especially to reduce the release of heat and smoke. Therefore, in this work, flame retardants PNIM and PNDA were prepared and introduced into EP to achieve the effective suppression of heat and smoke. EP/DDM/PNDA-10 can self-extinguish quickly, achieving the V-0 rating as well as the LOI value of 34.3%. Compared with the Control EP, the peak heat release rate (pHRR), total heat release (THR), and total smoke production (TSP) of EP/DDM/PNDA-10 decreased by 68.7%, 36.2% and 35.7%, respectively. It can be attributed to the P/N synergistic flame retardant effect. During the combustion process, PNIM and PNDA can promote the formation of a dense carbon layer containing phosphorus and nitrogen, retain pyrolysis products in the condensed phase, and simultaneously inhibit the transfer of heat and oxygen. In addition, the PO· and PO 2 · free radicals produced by the decomposition of flame retardants can capture the active free radicals in the air, thereby interrupting the combustion reaction. Simultaneously, non-flammable gases, such as N 2 and NH 3 were released, which diluted the concentration of combustible volatiles and oxygen and enhanced the gas phase flame-retardant effect. Furthermore, EP/DDM/PNIM-10 exhibited excellent mechanical properties, with tensile strength and impact strength increasing by 33.1% and 131.4%. In general, this work provides an approach to developing a phosphonitrile flame retardant with broad applications in high-performance EP.
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