Topology Effect of AIEgen-Appended Poly(acrylic acid) with Biocompatible Segments on Ca2+-Sensing and Protein-Adsorption-Resistance Properties

We recently reported that tetraphenylethene-appended poly(acrylic acid) derivatives (e.g., PAA-TPE0.02) can serve as fluorescent Ca2+ sensors in the presence of physiological concentrations of biologically relevant ions, amino acids, and sugars. However, in the presence of basic proteins such as albumins, the Ca2+-sensing property of the polymer is significantly impaired due to the nonspecific adsorption of protein molecules, which competes with binding to Ca2+. To solve this problem, we explored new designs by focusing on the polymer-chain topology of PAA-TPE0.02 with biocompatible segments. Here, we report the Ca2+-sensing and protein-adsorption-resistance properties of various types of PAA-TPE0.02 copolymers with a poly(oligoethylene glycol acrylate) (polyOEGA) segment, featuring a random, diblock, triblock, or 4-armed-star-block structure. Through this study, we show an interesting topology effect; i.e., a branch-shaped PAA-TPE0.02-co-polyOEGA with biocompatible segments at every terminal (i.e., 4-armed-star-block copolymer) exhibits both good Ca2+-sensing and protein-adsorption-resistance properties