Separation of poly(acrylic acid) salts according to topology using capillary electrophoresis in the critical conditions

Abstract

Branching was detected in polyacrylates synthesised through radical polymerization via solution-state NMR, while inconsistencies have been reported for the determination of the molar mass of hydrophilic polyacrylates using aqueous-phase and organic-phase size-exclusion chromatography. In this work, poly(sodium acrylate)s, PNaAs, of various topologies were separated for the first time using free-solution capillary electrophoresis (CE). Free-solution CE does not separate the PNaAs by their molar mass, similarly to separations by liquid chromatography in the critical conditions, rather by different topologies (linear, star branched, and hyperbranched). The electrophoretic mobility of PNaAs increases as the degree of branching decreases. Separation is shown to be not only by the topology but also by the end groups as expected for a separation in the critical conditions: replacing a relatively bulky nitroxide end group with hydrogen atom yielded a higher electrophoretic mobility. This novel method, capillary electrophoresis in the critical conditions enabled, for the first time, the separation of hydrophilic polyacrylates according to their topology (branching) and their chain ends. This will allow meaningful and accurate characterization of their branched topologies as well as molar masses and progress in for advanced applications such as drug delivery or flocculation.

Cellular Response to Linear and Branched Poly(acrylic acid)

“…Linear PNaA was obtained by anionic polymerization. 3‐arm star and hyperbranched PNaA samples were synthesized by nitroxide‐mediated polymerization (NMP) and precipitated to remove impurities. Precipitation was chosen as the most usual and fast purification method.…”

“…The 3‐arm star PAA and hyperbranched PAA samples were synthesized by nitroxide‐mediated polymerization of acrylic acid in 1,4‐dioxane initiated and controlled by the alkoxyamine BlocBuilder, which contains the nitroxide SG1 (as per ref. ). Sodium borate buffer (110 mM, pH 9.2) was prepared as per ref.…”

“…The instrument and conditions were as in ref. except when stated otherwise. Distributions of electrophoretic mobilities were calculated as in ref.…”

“…Particles with polystyrene core and PNaA shell exhibited high loading of cisplatin together with a controlled release, thus demonstrating the potential of PAA for cisplatin delivery. PAA can be produced as hyperbranched or star polymers . It is important to test the cytotoxicity of the delivery agent on its own to ensure that no unwanted side effects like toxicity to non‐cancerous cells occur.…”

“…The complexation of anticancer drugs to serum and plasma proteins, mainly transferrin and albumin, are accountable for the delivery and accumulation of anticancer drugs in cancer cells . Free solution capillary electrophoresis (CE), or capillary zone electrophoresis (CZE), was shown to be a simple and robust method to characterize the branched structure of PNaA through its electrophoretic mobility . The migration has never been attempted in physiological conditions.…”