Xuan Liang,Shuyun Wu,Xianyue Ren,Daping Quan,Li-Ming Zhang,Yubing Deng,Liqun Yang
A series of hyperbranched glycogen derivatives conjugated with different contents of cationic 3-(dimethylamino)-1-propylamine residues, named DMAPA-Glyp derivatives, were synthesized at room temperature. Resonance light scattering (RLS) spectroscopy was used to investigate the complexation behavior and efficacy of the DMAPA-Glyp derivatives and plasmid DNA (pDNA). Results indicated that the DMAPA-Glyp derivatives and pDNA molecules began to aggregate and form complexes at a weight ratio of 2. Following further increases in the DMAPA-Glyp derivatives (w/w >2), pDNA was condensed to form compact complexes. RLS spectroscopy is thus a useful tool for studying the complexation behavior and efficacy of cationic polymers with nucleic acid molecules. Circular dichroism analysis further revealed that the conformation of pDNA transformed from B-form to C-form and A-form during the complexation process.
Le Ma,Xiansheng Li,Xuehan Chen,Jingyu Li,Pengfei Liu,Changting Wei,Qingshan Ma,Leimeng Xu,Wenhua Zhang,Jizhong Song
Mixed halide CsPb(Br/Cl) 3 quantum dots (QDs) exhibit fine tunable blue light and narrow photoluminescence (PL) full-width at half-maximum (FWHM), which has attracted significant attention as a promising candidate to realize a new generation of blue light technology. However, the introduction of Cl − makes it very easy to be eroded by water in the environment, which will lead to deep-level defects and degrade the luminescence and stability of QDs. Here, we propose to introduce tetra- n -octylammonium oxalate (TOAOxa) to improve the water-resistance stability and exciton recombination of CsPb(Br/Cl) 3 QDs and QD-based light-emitting diodes (QLEDs). The oxalate ion (Oxa 2− ) of TOAOxa could form strong interaction with undercoordinated Pb 2+ on CsPb(Br/Cl) 3 QD surface, which was confirmed by FTIR and XPS analysis. Oxa 2− passivated QDs (Oxa-QDs) exhibited improved photoluminescence quantum yield (PLQY) and enhanced water-resistance stability compared to pristine QDs. For example, after soaking in water–acetone co-solvent for 1 h, Oxa-QDs can maintain the initial cubic morphology and 43.9% of initial PL intensity, while the morphology and luminescence of pristine QDs are almost damaged. Based on the above concept, the Oxa-QD-based QLED presented a maximum external quantum efficiency (EQE) of 4.0%, and operational lifetime (T 50 ) of 84 s, which was a 5-fold enhancement in EQE, and 7-fold enhancement in stability compared to pristine QLED, respectively. Besides, the Oxa-QD-based QLED exhibits better stability in high-humidity air. To sum up, the Oxa 2− passivation strategy has significantly improved the efficiency and water-resistant stability of QDs and devices and would rapidly promote the development of blue-emitting QDs.
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