  Although promising for biomedicine, the clinical translation of inorganic
nanoparticles (NPs) is limited by low biocompatibility and stability in
biological fluids. A common strategy to circumvent this drawback consists in
disguising the active inorganic core with a lipid bilayer coating, reminiscent
of the structure of the cell membrane to redefine the chemical and biological
identity of NPs. While recent reports introduced membrane coating procedures
for NPs, a robust and accessible method to quantify the integrity of the
bilayer coverage is not yet available. To fill this gap, we prepared SiO2
nanoparticles (SiO2NPs) with different membrane coverage degrees and monitored
their interaction with AuNPs by combining microscopic, scattering, and optical
techniques. The membrane-coating on SiO2NPs induces spontaneous clustering of
AuNPs, whose extent depends on the coating integrity. Remarkably, we discovered
a linear correlation between the membrane coverage and a spectral descriptor
for the AuNPs plasmonic resonance, spanning a wide range of coating yields.
These results provide a fast and cost-effective assay to monitor the
compatibilization of NPs with biological environments, essential for bench
tests and scale-up. In addition, we introduce a robust and scalable method to
prepare SiO2NPsAuNPs hybrids through spontaneous self assembly, with a high
fidelity structural control mediated by a lipid bilayer.
