Tuning the Cross-Linking Density and Cross-Linker in Core Cross-Linked Polymeric Micelles and Its Effects on the Particle Stability in Human Blood Plasma and Mice
Tobias Bauer, Irina Alberg, Lydia Zengerling, Pol Besenius, Kaloian Koynov, Bram Slütter, Rudolf Zentel, Ivo Que, Heyang Zhang, Matthias Barz
Abstract
High Resolution Image Download MS PowerPoint Slide Core cross-linked polymeric micelles (CCPMs) are designed to improve the therapeutic profile of hydrophobic drugs, reduce or completely avoid protein corona formation, and offer prolonged circulation times, a prerequisite for passive or active targeting. In this study, we tuned the CCPM stability by using bifunctional or trifunctional cross-linkers and varying the cross-linkable polymer block length. For CCPMs, amphiphilic thiol-reactive polypept(o)ides of polysarcosine- block -poly( S -ethylsulfonyl- l -cysteine) [pSar- b -pCys(SO 2 Et)] were employed. While the pCys(SO 2 Et) chain lengths varied from X n = 17 to 30, bivalent (derivatives of dihydrolipoic acid) and trivalent (sarcosine/cysteine pentapeptide) cross-linkers have been applied. Asymmetrical flow field-flow fraction (AF4) displayed the absence of aggregates in human plasma, yet for non-cross-linked PM and CCPMs cross-linked with dihydrolipoic acid at [pCys(SO 2 Et)] 17, increasing the cross-linking density or the pCys(SO 2 Et) chain lengths led to stable CCPMs. Interestingly, circulation time and biodistribution in mice of non-cross-linked and bivalently cross-linked CCPMs are comparable, while the trivalent peptide cross-linkers enhance the circulation half-life from 11 to 19 h.