Dually stimuli‐responsive hyperbranched polyethylenimine with LCST transition based on hydrophilic–hydrophobic balance

Abstract

Dually stimuli-responsive hyperbranched polyethylenimine derivatives (HPEI-star-PPOs) were successfully synthesized through Michael addition of commercial HPEI, poly(propylene oxide) dimethacrylate, and 2-mercaptoethanol. In aqueous solution, these HPEI-star-PPOs exhibited response to temperature and pH. The corresponding lower critical solution temperature (LCST) could be readily adjusted by changing the feed ratio of HPEI to PPO, which also presents the ratio of hydrophilicity to hydrophobicity, indicating that this LCST transition is based on hydrophilic-hydrophobic balance. Because of the tertiary amine as well as unreacted primary or secondary amine that can be protonated during pH decreases, HPEI-star-PPOs exhibited a pH-dependent thermoresponse. The 3-(4,5-dimethyl-thiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay against COS-7 cells demonstrated that HPEIstar-PPO had relatively low cytotoxicity compared to HPEI. All these characteristic suggest that this stimuli-responsive polymer is a promising functional material for biomedical applications. ARTICLE Figure 7. Cell viability of COS-7 cells against HPEI and HPEI-star-PPO-1 after 24 h of incubation with different concentrations.ARTICLE 3254

Tailoring the Supramolecular Structure of Aminated Polyrotaxanes Toward Enhanced Cellular Internalization

“…Because PRXs with larger numbers of threaded CDs per PRX are expected to possess increased structural rigidity, non‐stretched macromolecules containing similar composition of amino groups were required as control samples. For this reason, poly(2‐(dimethylamino) ethyl methacrylate (PDMAEM), which contains a similar number of amino groups as APRX 4 and possesses a random‐coil structure, was synthesized by atom transfer radical polymerization (ATRP) from an azide‐functionalized initiator . The fluorescent molecule AF‐545 was introduced by click chemistry at the terminal azide, affording fluorescently labeled PDMAEM (Figure ).…”

“…To evaluate the specific effect of PRX structure on cellular internalization, the degree of PRX internalization was compared with two series of aminated macromolecules, both of which possess random‐coil conformations in solution . The PDMAEM and the aminated pullulan exhibited significantly lower florescence intensities than APRX 4 (Figure ).…”

Recent advances of on-demand dissolution of hydrogel dressings

“…The polymers can form a semi-rigid gel through the hydrophobic interactions or secondary bonding, and these bonds between the polymer chains can be changed with increased temperature [74]. TPCH can undergo the hydrophilic-hydrophobic transition via the hydrophobic interaction when temperature is above the lower critical solution temperature (LCST) [75]. The polymer solution has the low viscosity at room temperature, but it will turn into gel when the temperature is above the LCST.…”

Post polymer modification of polyethylenimine with citrate esters: selectivity and hydrophobicity

“…For instance, PEI has been reacted with acid chlorides, 37 anhydrides, 38,39 aldehydes, 40 alkyl halides, 37 carbonates, 41 carboxylic acids, 42 and methacrylates. 43 Many of these hydrophobic modifications improve electrospinning, gene transfection, and alter LCST behavior. However, these studies are representative of the widespread empirical efforts and approaches to addressing hydrophobicity.…”