Amphoteric calix[8]arene-based complex for pH-triggered drug delivery

Amphoteric calix[8]arene with negatively charged upper rim and positively charged lower rim was synthesized based on water-soluble p-sulfonato-calix[8]arene. The pH-sensitive amphoteric calix[8]arenes exhibit not only a good hydrophobic drug loading capacity but also a pH-triggered drug releasing behavior. The in vitro release studies demonstrated that release of ciprofloxacin from amphoteric calix[8]arene complexes was highly pH-sensitive. More efficient drug release was observed at mildly acidic pH 5.0 and basic pH 8.5 compared to physiological pH. The amphoteric calix[8]arene complexes hold out great promise of being pH-sensitive drug carrier.

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► Amphoteric calix[8]arenes with negative charged upper rim and positively charged lower rim were prepared.
► The amphoteric calix[8]arenes exhibit a good hydrophobic drug loading capacity.
► Coupled calix[8]arene complexes or multilayers are formed around pH 7.0 via electrostatic attraction.
► The drug release from the calix[8]arene complexes can be triggered by changing pH conditions.