A novel salt-responsive hydrogel on the base of calixresorcinarene–mPEG amide conjugate

A novel low toxic amide calix[4]resorcinarene–mPEG conjugates of amphiphilic and dendrimeric character were synthesized. It was shown that the growth of the temperature or the ionic strength growth of the solution leads to different demonstration of the amplification of hydrophobic interactions in the conjugates self-associates. It was found that in PBS or 0.9 % NaCl solutions the amphiphilic conjugate form micellar solution, and the dendrimeric conjugate – hydrogel, which is capable of the reversible sol-gel transition. It was shown by DSC analysis that the dendrimeric conjugate binds of 15 % of water molecules in an aqueous solution (non-freezing bound water), but in the salt solution the conjugate-water interaction is practically absent. This leads to the additional self-aggregation of conjugate molecules and to the gel formation. The high degree of substrate sorption by the hydrogel (Methylene Blue, encapsulation effectiveness is 78 %) and its reversible binding-release by the regulation of the solution ionic strength have been demonstrated

The highly regioselective synthesis of novel imidazolidin-2-ones via the intramolecular cyclization/electrophilic substitution of urea derivatives and the evaluation of their anticancer activity

A series of novel 4-(het)arylimidazoldin-2-ones were obtained by the acid-catalyzed reaction of (2,2-diethoxyethyl)ureas with aromatic and heterocyclic C-nucleophiles. The proposed approach to substituted imidazolidinones benefits from excellent regioselectivity, readily available starting materials and a simple procedure. The regioselectivity of the reaction was rationalized by quantum chemistry calculations and control experiments. The anti-cancer activity of the obtained compounds was tested in vitro

The pH-responsive calix[4]resorcinarene-mPEG conjugates bearing acylhydrazone bonds: Synthesis and study of the potential as supramolecular drug delivery systems

© 2020 Elsevier B.V. The synthesis of new conjugates of calix[4]resorcinarenes and methoxy-PEG via acylhydrazone bonds and their study in the formation of pH-sensitive low-toxic supramolecular drug delivery systems have described. The syntheses have been performed on the base of two calix[4]resorcinarenes in chair and boat conformations to obtain the dendrimer-like and amphiphilic conjugates, respectively. The structures of the conjugates have been confirmed by 1H, 13C NMR, and FT-IR spectroscopy, Maldi-TOF mass spectroscopy, and SLS method. The self-association of both amphiphilic and dendrimer-like conjugates has been found (NMR FT-PGSE, fluorimetry, DLS and TEM methods). The hydrolysis of the conjugates at pH 5.5 (proved by 1H NMR and FT-IR spectroscopy, DLS method) lead to the improved release of the conjugate-encapsulated Dox. The low hemolytic activity and low cytotoxicity against Chang liver cells of the conjugates and products of their hydrolysis have been demonstrated. Meanwhile, the improved cytotoxicity and photodynamic activity of conjugates-encapsulated drugs (Dox and Methylene Blue, respectively) has been found in vitro. The results have indicated the potential using of the calix[4]resorcinarene-mPEG conjugates bearing acylhydrazone bonds as supramolecular drug delivery systems

Introduction of isothiuronium surfactant series: Synthesis, structure-dependent aggregation overview and biological activity

© 2020 Elsevier B.V. For a homologous series of isothiuronium surfactants (S-alkylisothiuronium bromides, CnSU, where n = 10, 12, 14, 16, 18), a synthesis procedure is described and aggregation properties are comprehensively characterized by a variety of techniques. Krafft temperature and critical micelle concentration (cmc) are obtained by methods of conductometry, tensiometry, spectrophotometry, fluorimetry. Using dynamic light scattering and NMR diffusometry, aggregate sizes in aqueous solutions were determined. The aggregation numbers of CnSU systems were estimated by alternative methods. An increase in the length of the alkyl tail from 10 to 16 carbon atoms leads to a decrease in cmc from 16 to 0.5 mM with a decrease in aggregation numbers. S-alkylisothiuronium bromides exhibit solubilization capacity toward a hydrophobic dye Orange OT which is 2–3 times higher than that of alkyltrimethylammonium analogues. Improved solubilization characteristics along with antimicrobial properties manifested at the concentrations of low hemolytic activity allow us to recommend these amphiphiles for the fabrication of soft nanocontainers for hydrophobic guests showing their own biological functionality

Synthesis of Ag-AgCl nanoparticles capped by calix[4]resorcinarene-mPEG conjugate and their antimicrobial activity

© 2020 Elsevier B.V. The growing resistance of bacteria to traditional antibiotics makes it necessary to develop new antimicrobial agents with the dissimilar mode of action such as Ag and AgCl nanoparticles. Here the synthesis of silver NPs in the colloidal solutions of calix[4] resorcinarene-mPEG conjugate C11-mPEG was reported. NPs were synthesized under varied conditions: different Ag+/C11-mPEG molar ratio, presence/absence of reducing agent (NaBH4), in dark or LED light exposure. It was found that in all cases Ag-AgCl NPs, stabilized by C11-mPEG, were obtained with the difference in the Ag NPs content and sizes. Physicochemical characteristics of the Ag-AgCl@C11-mPEG NPs were evaluated by UV–vis, FT-IR, XRPD, XRF, DLS, and TEM methods. The antimicrobial activity of NPs against Gram-positive and Gram-negative bacteria and fungi was studied and the preferred antimicrobial activity against Gram-positive bacteria was found. The proposed scheme of Ag-AgCl@C11-mPEG NPs and the influence of NPs content on the antimicrobial activity were discussed