Patterned Arrays of Supramolecular Microcapsules09 May 2018
Micropatterning of hydrogel has brought innovative outcomes in fundamental and applied material sciences. Previous approaches have mainly been dedicated to fabricate arrays of bulk hydrogel beads, which have inherent challenges including loading ability, scalability, specificity and versatility. Here we present a methodology to create hollow microcapsule arrays from sessile microdroplets. The difference in wettability between hydrophilic and hydrophobic surfaces enables self-partitioning of liquid into microdroplet arrays, serving as microreservoirs to load complementarily-functionalized host-guest polymers, cucurbituril-threaded highly-branched polyrotaxanes (HBP-CB) and naphthyl-functionalized hydroxyethyl cellulose (HEC-Np). The interfacial dynamic complexation between positively-charged HBP-CB and HECNp occurred in the presence of negatively-charged surfactants, resulting in condensed supramolecular hydrogel skins. The hydrogel microcapsules were uniform in size, and were developed to encapsulate target cargos in a robust and well-defined manner. Moreover, the microcapsule substrates were further used for surface enhanced Raman spectroscopy (SERS) sensing upon loading of gold nanoparticles. This facile assembly of microcapsule arrays has potential applications in controlled cargo delivery, bio-sensing, high throughput analysis and sorting.