<p class="first" id="P1">Colloidal gels that combine oppositely charged nanoparticles
are increasingly leveraged
for drug delivery and tissue engineering applications. Meanwhile, cell membrane-coated
nanoparticles are becoming unique biomimetic nanomedicine for innovative therapeutics.
Inspired by the remarkable potential of both platforms, herein we investigate the
use of cell membrane-coated nanosponges as building blocks to form colloidal gel.
Specifically, we prepare red blood cell membrane-coated nanoparticles (namely ‘nanosponges’,
denoted ‘RBC-NPs’). In the presence of appropriate cationic nanoparticles, the nanosponges
self-assemble to form a gel-like and cohesive complex (namely ‘nanosponge colloidal
gel’, denoted ‘NC-gel’). When applied with an external shear force, the NC-gel shows
shear-thinning behavior; however, upon removal of the external force, the cohesive
property recovers. The NC-gel not only preserves the toxin neutralization capability
of the nanosponges, but also prolongs their retention after subcutaneous injection
into mouse tissues. In a mouse model of subcutaneous Group A
<i>Streptococcus</i> (GAS) infection, the NC-gel shows significant antibacterial efficacy
reducing skin lesion development. Overall, we demonstrate the successful use of cell
membrane-coated nanoparticles as building blocks to formulate colloidal gel that entirely
based on material self-assembly without chemical cross-linking. The new colloidal
gel system is promising as an injectable formulation for therapeutic applications
such as antivirulence treatment for local bacterial infections.