Physicochemical characterization of amphiphilic nanoparticles based on the novel starch–deoxycholic acid conjugates and self-aggregates

•The novel amphiphilic starch–deoxycholic acid conjugates were firstly synthesized.•Starch was hydrophobically modified by introducing deoxycholic acid.•Physicochemical characterizations were investigated in detail.•Starch–deoxycholic acid conjugates could self-aggregate in PBS solution.•Amphiphilic nanoparticles had a good pH-responsive. Novel amphiphilic polymers (starch–deoxycholic acid, St–DCA) were firstly synthesized on the basis of starch (St) as a hydrophilic segment and deoxycholic acid (DCA) as a hydrophobic segment. Hydrophobically modified starch contained 5.4–8.9 deoxycholic acid groups per 100 anhydroglucose units of starch. Self-aggregates of St–DCA conjugates were formed in the PBS media. Physicochemical characterizations of St–DCA conjugates were investigated. The mean sizes of self-aggregates decreased with the degree of substitution (DS) and pH increasing. Zeta potential indicated that nanoparticles were covered with negatively charged starch shells from −5.4 to −23mV. TEM images demonstrated that nanoparticles were of spherical shape. The critical aggregation concentrations (cac) were dependent on the DS and pH in the range of 0.0185–0.0441mg/mL. Thus, the study suggested that self-aggregated nanoparticles of St–DCA conjugates could have good pH-responsive and potential application in pharmaceutical and biomedical fields as the delivery of anti-tumor drugs.