Temperature-sensitive poly(N-(2-hydroxypropyl)methacrylamide mono/dilactate)-coated liposomes for triggered contents release.

We prepared thermosensitive poly(N-(2-hydroxypropyl)methacrylamide mono/dilactate) (pHPMA mono/dilactate) polymer and studied temperature-triggered contents release from polymer-coated liposomes. HPMA mono/dilactate polymer was synthesized with a cholesterol anchor suitable for incorporation in the liposomal bilayers and with a cloud point (CP) temperature of the polymer slightly above normal body temperature (42 °C). Dynamic light scattering (DLS) measurements showed that whereas the size of noncoated liposomes remained stable upon raising the temperature from 25 to 46 °C, polymer-coated liposomes aggregated around 43 °C. Also, noncoated liposomes loaded with calcein showed hardly any leakage of the fluorescent marker when heated to 46 °C. However, polymer-coated liposomes showed a high degree of temperature-triggered calcein release above the CP of the polymer. Likely, liposome aggregation and bilayer destabilization are triggered because of the precipitation of the thermosensitive polymer above its CP ...