Two dimensional layered double hydroxides augment antigen loading and release

Layered double hydroxides (LDHs) are anionic nanoscale clays with multiple applications in medicine including drug delivery, immunotherapy and cancer treatment. The layered structure of LDHs with positive surface charge enables them to serve as nanoplatforms for biomolecule loading and release. Nonetheless, how the LDH metal composition influences protein encapsulation efficiency, cellular uptake, and release kinetics remains unclear. We evaluated the drug-loading capacity of eight different LDHs synthesized using coprecipitation and hydrothermal treatment. The LDHs were loaded with ovalbumin (OVA), and their performance was compared to that of the commercial adjuvant alum. Among the different LDHs tested, ZnAl and MgAl LDHs showed more than 80% OVA encapsulation efficiency, wherein ZnAl LDHs showed an ~15% increase in OVA-loading compared with alum. The ZnAl LDH-OVA and MgAl LDH-OVA samples were more readily and rapidly taken up by MCF-7 breast cancer cells and primary spleen cells than pure OVA or OVA-loaded alum were. Approximately 82% of the loaded OVA was released from alum within 48 h, whereas 65% and 54% of the loaded OVA was released from ZnAl LDH and MgAl LDH within 48 h, respectively, indicating a sustained release profile.