Yuan Libo,Wang Ke,Fang Yuan,Xu Xiujuan,Chen Yingcun,Zhao Dongxin,Lu Kui
Cecropin A (1–7) is a cationic antimicrobial peptide which contain lots of basic amino acids. To understand the effect of basic amino acids on cecropin A (1–7), analogues CA2, CA3 and CA4 which have more arginine or lysine at the N-terminal or C-terminal were designed and synthesized. The interaction of cecropin A (1–7) and its analogs with DNA was studied using ultraviolet–visible spectroscopy, fluorescence spectroscopy and circular dichroism spectroscopy. Multispectral analysis showed that basic amino acids improved the interaction between the analogues and DNA. The interaction between CA4 and DNA is most pronounced. Fluorescence spectrum indicated that Ksv value of CA4 is 1.19 × 10 5 L mol −1 compared to original peptide cecropin A (1–7) of 3.73 × 10 4 L mol −1 . The results of antimicrobial experiments with cecropin A (1–7) and its analogues showed that basic amino acids enhanced the antimicrobial effect of the analogues. The antimicrobial activity of CA4 against E. coli was eightfold higher than that of cecropin A (1–7). The importance of basic amino acid in peptides is revealed and provides useful information for subsequent studies of antimicrobial peptides. Graphical Abstract
In this study, two fluorescence conjugated microporous polymers based on perylene tetraanhydride bisimide (DP4A0 and DP4A2) were prepared via Sonogashira–Hagihara cross-coupling polymerization for the efficient detection of o-nitrophenol (o-NP). They were well characterized via FT-IR, solid state 13C NMR, elemental analysis, and other material characterization techniques. The experiments proved that both CMPs possess high thermal and chemical stability and a porous nature with Brunauer–Emmett–Teller (BET) specific surface areas of 41.3 and 402.1 m2 g−1. Importantly, owing to signal amplification by the conjugated skeleton, DP4A0 and DP4A2 exhibit extremely high sensitivity to o-NP with Ksv values of 1.83 × 104 and 1.69 × 104 L mol−1 and limits of detection of 5.73 × 10−9 and 7.36 × 10−9 mol L−1, respectively. The sensing performance of DP4A0 and DP4A2 was dependent on the position of crosslinking points and crosslinking density. Finally, super amplified quenching was considered the electron transfer mechanism and hydrogen bond interactions were also present.
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