Synthesis and volume phase transitions of glucose-sensitive microgels.
By the functionalization of poly(N-isopropylacrylamide-co-acrylic acid) microgels with 3-aminophenylboronic acid (APBA) via carbodiimide coupling, nearly monodisperse glucose-sensitive P(NIPAM-PBA) microgels with a diameter of several hundred nanometers were synthesized in aqueous media. Dynamic laser light scattering was used to study the glucose-sensitive and thermosensitive behaviors of the resultant microgels under various conditions. The introduction of the hydrophobic phenylboronic acid (PBA) group significantly decreases the volume phase transition temperature of the resultant microgels. As a result, the P(NIPAM-PBA) microgels with a 10.0 mol % PBA content are in a collapsed state at room temperature. However, the addition of glucose makes the microgels swell dramatically. The glucose-sensitivity of the PBA-containing microgels relies on the stabilization of the charged phenylborate ions by binding with glucose, which can convert more hydrophobic PBA groups to the hydrophilic phenylborate ions. The presence of glucose also induces a two-stage volume phase transition of the P(NIPAM-PBA) microgels, which is explained by the core-shell-like heterogeneous structure of the microgels induced by the formation of the unique glucose-bis(boronate) complex in the "core" area of the microgels. The effects of pH, ionic strength, and PBA content on the glucose sensitivity of the P(NIPAM-PBA) microgels were investigated.
Zhang
Yongjun
Y
Department of Chemistry and The Center for Engineered Polymeric Materials of College of Staten Island, and The Graduate Center, The City University of New York, 2800 Victory Boulevard, Staten Island, New York 10314, USA.
Guan
Ying
Y
Zhou
Shuiqin
S
D005782:Gels; D005947:Glucose / Q000138:chemical synthesis*; D006863:Hydrogen-Ion Concentration; D009994:Osmolar Concentration; D017550:Spectroscopy, Fourier Transform Infrared
D005782:Gels; D005947:Glucose