Highly efficient evaporation method to prepare pH-responsive lignin-hollow-nanosphere with controllable size and its application in oral drug delivery

In this study, we establish a novel highly efficient preparation process to prepare homogeneous and size controllable pH-responsive lignin nanosphere (LN). Orthogonal experiments have been performed to investigate the effects of the factors (bath temperature, lignin concentration, starting volume, cooling temperature) on the effective diameters (ED) and polydispersity index (PDI) of LN. The fast vacuum evaporation process could also encapsulate drugs in the one-pot process, with the solvent acetone recycled simultaneously. The drug release based on pH-responsive have been investigated. As a result, homogenous LN with targeted size (within 100 ∼ 400 nm) had been obtained under the preparation conditions suggested by the established Models. The matrix entrapment efficiency of LN was 47 %. The lignin encapsulating Ibuprofen nanospheres showed excellent pH-responsive release. It had just 18 % released at pH 1.2, while over 90 % at pH7.5 for 2−6 h. This study introduced a highly efficient way to prepare lignin nanospheres and a new strategy to prepare pH-responsive drugs.