title: pH-responsive poly(styrene-alt-maleic anhydride) alkylamide copolymers for intracellular drug delivery.
abstract: Many macromolecular therapeutics such as peptides, proteins, antisense oligodeoxynucleotides (ASODN), and short interfering RNA (siRNA) are active only in the cytoplasm or nucleus of targeted cells. Endocytosis is the primary route for cellular uptake of these molecules, which results in their accumulation in the endosomal-lysosomal trafficking pathway and loss of therapeutic activity. In this article, we describe the synthesis and pH-dependent membrane-destabilizing activity of a new "smart" polymer family that can be utilized to enhance the intracellular delivery of therapeutic macromolecules through the endosomal membrane barrier into the cytoplasm of targeted cells. These polymers are propylamine, butylamine, and pentylamine derivatives of poly(styrene-alt-maleic anhydride) (PSMA) copolymers. The PSMA-alkylamide derivatives are hydrophilic and membrane-inactive at physiological pH; however, they become hydrophobic and membrane-disruptive in response to endosomal pH values as measured by their hemolytic activity. Results show that the pH-dependent membrane-destabilizing activity of PSMA derivatives can be controlled by varying the length of the alkylamine group, the degree of modification of the copolymer, and the molecular weight of the PSMA copolymer backbone. Butylamine and pentylamine derivatives of PSMA copolymers exhibited more than 80% hemolysis at endosomal pH values, which suggests their potential as a platform of "smart" polymeric carriers for enhanced cytoplasmic delivery of a variety of therapeutic macromolecules.
authors.affiliation: University of Washington, Department of Bioengineering, Seattle, Washington 98195, USA.
authors.forename: Scott M
authors.initials: SM
authors.lastname: Henry
authors.forename: Mohamed E H
authors.initials: ME
authors.lastname: El-Sayed
authors.forename: Christopher M
authors.initials: CM
authors.lastname: Pirie
authors.forename: Allan S
authors.initials: AS
authors.lastname: Hoffman
authors.forename: Patrick S
authors.initials: PS
authors.lastname: Stayton
mesh_terms: D000818:Animals; D016503:Drug Delivery Systems; D011992:Endosomes / Q000737:chemistry; D004912:Erythrocytes / Q000737:chemistry / Q000166:cytology; D006461:Hemolysis / Q000187:drug effects; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008299:Maleic Anhydrides / Q000138:chemical synthesis* / Q000737:chemistry / Q000493:pharmacokinetics; D051379:Mice; D041681:NIH 3T3 Cells; D011108:Polymers / Q000138:chemical synthesis* / Q000737:chemistry / Q000493:pharmacokinetics; D011137:Polystyrenes / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology
chemical_list: D008299:Maleic Anhydrides; D011108:Polymers; D011137:Polystyrenes; C016683:polymaleic anhydride