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.

Automated summary

A novel low toxic amide calix[4]resorcinarene-mPEG conjugates with amphiphilic and dendrimeric character were synthesized, showing different self-association behaviors based on temperature and ionic strength. Amphiphilic conjugates formed micellar solutions while dendrimeric conjugates formed hydrogels capable of reversible sol-gel transition. DSC analysis indicated water molecules binding to dendrimeric conjugates in aqueous solutions and the absence of conjugate-water interaction in salt solutions, leading to additional self-aggregation and gel formation. The hydrogel demonstrated high substrate sorption and reversible binding-release by regulating solution ionic strength.