Lignin-based pH-responsive nanocapsules
were successfully fabricated
via an interfacial miniemulsion polymerization. Lignin was first grafted
with allyl groups through etherification and further dispersed in
an oil-in-water (O/W) miniemulsion system via ultrasonication. Then
allyl-functionalized lignin was reacted with a thiol-based cross-linking
agent in the interfaces of miniemulsion droplets to form nanocapsules
via a thiol–ene radical reaction. The FTIR and 1H NMR spectra indicated the successful grafting of allyl groups on
lignin. TEM images showed that lignin nanocapsules had particle sizes
ranging from 50 to 300 nm. These newly synthesized nanocapsules could
be readily loaded with hydrophobic coumarin-6 during the preparation
of a miniemulsion system with 0.713 mmol/g entrapment efficiency.
Moreover, the release of encapsulated coumarin-6 could be controlled
by varying pH in the solution due to the existence of acid-labile
β-thiopropionate cross-linkages in the capsule shell. An approximately
linear release profile was observed at pH 7.4, whereas the release
followed a Korsmeyer–Peppas profile at pH 4. The syntheses
of lignin-based nanocapsules not only provide a facile approach to
utilize the waste biomaterials from biorefinery industries, but also
have great potential for applications in a controllable delivery of
hydrophobic molecules such as drugs, essential oils, antioxidants,
etc.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.