Copolymers of N‐isopropylacrylamide can trigger pH sensitivity to stable liposomes

Abstract

Stable liposomes were rendered pH-sensitive by complexation to a polymer that undergoes marked temperatureand pH-dependent water solubility changes. The N-isopropylacrylamide-methacrylic acid copolymer was prepared with or without octadecyl acrylate. At pH below the phase transition of the polymer, egg phosphatidylcholine liposomes quickly released a part of their contents only when associated with the octadecyl aliphatic chain grafted polymer at 37³C. Similarly, sterically stabilized liposomes also quickly released a significant part of the entrapped fluorescent markers at pH 5.5^4.9, values corresponding to those of endosomes/lysosomes. This new pH-sensitive liposome-polymer system may further improve the efficiency of liposomal drug delivery.z 1998 Federation of European Biochemical Societies.

Targeted polymeric micelles for delivery of poorly soluble drugs

“…by combining the EPR effect with stimuli responsiveness. For this purpose, micelles are made of thermo-or pH-sensitive components such as poly(N-isopropylacrylamide) and its copolymers with poly(D,L-lactide) and other blocks, and acquire the ability to disintegrate in target areas, releasing the micelle-incorporated drug [33,44,[98][99][100]. pH-responsive polymeric micelles loaded with phtalocyanine seem to be promising carriers for photodynamic cancer therapy [101], while doxorubicin-loaded polymeric micelles containing acid-cleavable linkages provided an enhanced intracellular drug delivery into tumor cells and thus higher efficiency [102].…”

Targeted pharmaceutical nanocarriers for cancer therapy and imaging

“…Some of the carriers can be engineered in such a way that they can be activated by changes in the environmental pH, by chemical stimuli, by the application of a rapidly oscillating magnetic fi eld, or by application of an external heat source. [36][37][38][39] Such modifi cations offer control over particle integrity, drug delivery rates, and the location of drug release, for example, within specifi c organelles. Some carriers are being designed with a focus on multifunctionality, targeting cell receptors and delivering drugs and biological sensors simultaneously.…”

Review on nano-drugs

“…component to form the polymer micelle. Drug-loaded micelles in the specific temperature or acidity can be easily depolymerized and released the drugs [16][17][18]. Thomas [19] reported a new type of temperature-sensitive nanoparticles.…”