Micelles self-assembled from thermoresponsive 2-hydroxy-3-butoxypropyl starches for drug delivery

A new class of thermoresponsive polymers, 2-hydroxy-3-butoxypropyl starches (HBPS), was synthesized by changing the hydrophobic–hydrophilic balance of starch using butyl glycidyl ether as hydrophobic reagent. The lower critical solution temperatures (LCSTs) of HBPS can be adjusted by varying the molar substitution (MS) of hydrophobic groups in the range of 4.5–32.5 °C. In water, HBPS can self-assemble into micelles below the LCST, and the micelles are deformed and aggregate into more polar and larger objects above the LCST. The drug loading HBPS micelles showed thermoresponsive controlled release, namely, the drug release is accelerated dramatically above the LCST.