In order to obtain a simple and accurate calculation method of shielding effectiveness for woven fabric containing metal fiber yarns, a conductive grid structure model composed of two parallel metal yarn periodic arrays was established. The two periodic arrays were cross-arrangement. The calculation formula of shielding effectiveness for the fabric was deduced through the transfer matrix of the electromagnetic field. The theoretical value of shielding effectiveness of the fabric using the theoretical formula and the measured value tested by the shielding chamber method were compared. Both sets of data were analyzed respectively from the metallic yarn periodic spacing, diameter, electric conductivity, electromagnetic wave polarization direction, and the weaving angle. The result shows that a reasonable agreement between the theoretical value and the measured value has been achieved in a frequency range from 4 to 14 GHz. This shows that the theoretical calculation model is simple, highly precise, and is valuable for the design and development of fabric containing metal fiber yarns. It can be used for estimating the electromagnetic shielding effectiveness of the fabric.

Antimicrobial peptides have received increasing attention as potential antitumor drugs due to their new mode of action. However, the systemic toxicity at high concentration always hampers their successful utilization for tumor therapy. Here, we designed a new type of acid-activated antimicrobial peptide AMitP by conjugating antimicrobial peptide MitP to its anionic binding partner MitPE via a disulfide linker. Compared with MitP, AMitP displayed significant antitumor activity at acidic pH and low cytotoxicity at normal pH. The results of MD simulations demonstrate that the changes of structure and membrane binding tendency of AMitP at different pH values played an important role in its pH-dependent antitumor activity. In addition, AMitP showed significant enzymatic stability compared with MitP, suggesting a potential for in vivo application. In short, our work opens a new avenue to develop antimicrobial peptides as potential antitumor drugs with high selectivity.

A crucial bottleneck in nonviral vector-mediated gene delivery is poor endosomal escape. Here, we constructed novel gene vectors by coupling the stearyl moiety to the N-terminus of the antimicrobial peptide melittin (stearyl-Mel) and its retro isomer (stearyl-rMel) due to their high membrane-lytic activity. As expected, stearyl-Mel showed obvious increases in endosome-lytic activity and transfection efficiency compared with the reported stearyl-TP10. More gratifyingly, the transfection efficiency of stearyl-rMel was around 10-fold greater than that of stearyl-Mel and almost reached the transfection levels of Lipofectamine 2000 due to the enhanced endosome-lytic activity. Furthermore, the stearyl-rMel/p53 plasmid complex exhibited higher p53 expression and antitumor activity than stearyl-Mel, confirming the fact that stearyl-rMel displayed higher transfection efficiency. Taken together, the combination of the stearyl moiety with retro melittin provides a novel framework for the development of excellent nonviral gene vectors.

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