Abstract
In this work, we investigated aggregation of native DNA and thiacalix[4]arene derivative bearing eight terminal amino groups in cone configuration using various redox probes on the glassy carbon electrode. It was shown that sorption transfer of the aggregates on the surface of the electrode covered with carbon black resulted in changes in electrostatic interactions and diffusional permeability of the surface layer. Such changes alter the signals of ferricyanide ion, methylene green and hydroquinone as redox probes to a degree depending on their specific interactions with DNA and own charge. Inclusion of DNA in the surface layer was independently confirmed by scanning electron microscopy, electrochemical impedance spectroscopy and experiments with doxorubicin as a model intercalator. Thermal denaturing of DNA affected the charge separation on the electrode interface and the signals of redox probes. Using hydroquinone, less sensitive to electrostatic interactions, made it possible to determine from 10 pM to 1.0 nM doxorubicin (limit of detection 3 pM) after 10 min incubation. Stabilizers present in the commercial medications did not alter the signal. The DNA sensors developed can find future application in the assessment of the complexes formed by DNA and macrocycles as delivery agents for small chemical species.
Highlights
The complexation was studied by the UV spectroscopy, dynamic light scattering and transmission electron microscopy and resulted in formation of the aggregates with the size within
TC were characterized using a number of small redox active species
Adsorption of the DNA and thiacalix[4]arene derivative bearing eight terminal amino groups in cone configuration on the Glassy carbon electrode (GCE) modified with CB alters the conditions of the electron transfer monitored by the redox probes
Summary
Complexation of the DNA molecules with the polymeric and macrocyclic carriers has become popular in recent decades due to growing interest in the application of DNA vaccines and oligonucleotide-based drugs [1]. Chemical encapsulation via multiple noncovalent interactions is considered as one of the most promising issues in this area of research [10] It includes the formation of polyelectrolyte complexes with natural [11] and synthetic [12,13] counterparts, self-assembling of solid lipid nanoparticles, liposomes and vesicles [14,15,16]. The aggregation and self-aggregation of the macrocycles were promoted by the DNA binding This made it possible to assemble solid lipid nanoparticles with inclusion of hydrophobic guests and to determine the DNA intercalators with electrochemical sensors. In these works, the importance of the microenvironment of the macrocyclic core on the aggregation and the DNA binding abilities was confirmed.
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