1. Poly(l-glutamic acid)-Based Zwitterionic Polymer in a Charge Conversional Shielding System for Gene Therapy of Malignant Tumors
Jie Chen, Zhaopei Guo, Zixue Jiao, Lin Lin, Caina Xu, Huayu Tian, Xuesi Chen ACS Appl Mater Interfaces. 2020 Apr 29;12(17):19295-19306. doi: 10.1021/acsami.0c02769. Epub 2020 Apr 14.
Recently, pH-sensitive polymers have received extensive attention in tumor therapy. However, the rapid response to pH changes is the key to achieving efficient treatment. Here, a novel shielding system with a rapidly pH-responsive polymer (PAMT) is synthesized by click reaction between poly(γ-allyl-l-glutamate) and thioglycolic acid or 2-(Boc-amino)ethanethiol. The zwitterionic biodegradable polymer PAMT, which is negatively charged at physiological pH, can be used to shield positively charged nanoparticles. PAMT is electrostatically attached to the surface of the positively charged PEI/pDNA complex to form a ternary complex. The zwitterionic PAMT-shielded complex exhibits rapid charge conversion when the pH decreases from 7.4 to 6.8. For the in vivo tumor inhibition experiment, PAMT/PEI/shVEGF injected intravenously shows a more significant inhibitory effect on tumor growth. The excellent results are mainly attributed to introduction of the zwitterionic copolymer PAMT, which can shield the positively charged PEI/shVEGF complex in physiological conditions, while the surface potential of the shielded complexes changes to a positive charge in the acidic tumor environment.
2. Synthesis of active, robust and cationic Au25 cluster catalysts on double metal hydroxide by long-term oxidative aging of Au25(SR)18
Shinya Masuda, Shinjiro Takano, Seiji Yamazoe, Tatsuya Tsukuda Nanoscale. 2022 Feb 24;14(8):3031-3039. doi: 10.1039/d1nr07493h.
Synthesis of an atomically precise Au25 cluster catalyst was attempted by long-term, low-temperature aging of Au25(BaET)18 (BaET-H = 2-(Boc-amino)ethanethiol) on various double metal hydroxide (DMH) supports. X-ray absorption fine structure analysis revealed that bare Au25 clusters with high loading (1 wt%) were successfully generated on the DMH containing Co and Ce (Co3Ce) by oxidative aging in air at 150 °C for >12 h. X-ray absorption near-edge structure and X-ray photoelectron spectroscopies showed that the Au25 clusters on Co3Ce were positively charged. The Au25/Co3Ce catalyst thus synthesized exhibited superior catalytic performance in the aerobic oxidation of benzyl alcohol under ambient conditions (TOF = 1097 h-1 with >97% selectivity to benzoic acid) and high durability owing to a strong anchoring effect. Based on kinetic experiments, we propose that abstraction of hydride from α-carbon of benzyl alkoxide by Au25 is the rate-determining step of benzyl alcohol oxidation by Au25/Co3Ce.
