A series of novel molecules with a cyclen (1,4,7,10-tetraazacyclododecane) moiety appended on and bearing different aromatic fragments in the structures were synthesized and characterized. The binding activities of these compounds towards DNA were systematically studied by spectroscopic, viscometric and gel electrophoresis methods. The results suggest that the stacking interaction plays an important role in improving the DNA binding ability of the compounds. The binding modes of the compounds towards DNA are also affected by the sizes of the aromatic rings. The binding interaction between binaphthyl compound 1b and several nucleosides was studied by fluorescence titration. Stacking interaction and hydrophobic interaction play the key role in such non-selective binding process.stacking and hydrophobic interactions, DNA binding, aromatic compounds, nucleosides, oligonucleotides

Two dinucleotide PNA-cyclen copper(II) complexes with -PNA (P1) and classical PNA (P2) backbones were synthesized and characterized. The interactions between title complexes and DNA were investigated under physiological conditions. Fluorescence studies indicate that the binding ability of complex P1 to CT-DNA is as twice as that of P2. DNA melting experiments were also carried out and the results show that T m caused by P1 is higher than that caused by P2. Agarose gel electrophoresis experiments demonstrate that P1 is an excellent chemical nuclease, which can cleavage plasmid DNA completely in 12 h.

The traditional username/password or PIN based authentication scheme, which still remains the most popular form of authentication, has been proved insecure, unmemorable and vulnerable to guessing, dictionary attack, key-logger, shoulder-surfing and social engineering. Based on this, a large number of new alternative methods have recently been proposed. However, most of them rely on users being able to accurately recall complex and unmemorable information or using extra hardware (such as a USB Key), which makes authentication more difficult and confusing. In this paper, we propose a Digital Memories based user authentication scheme adopting homomorphic encryption and a public key encryption design which can protect users’ privacy effectively, prevent tracking and provide multi-level security in an Internet & IoT environment. Also, we prove the superior reliability and security of our scheme compared to other schemes and present a performance analysis and promising evaluation results.