posted on 2024-03-13, 18:05authored byYifeng Cai, Nada Y. Naser, Jinrong Ma, François Baneyx
Thermoresponsive elastin-like peptides (ELPs) have been
extensively
investigated in biotechnology and medicine, but little attention has
been paid to the process by which coacervation causes ELP-decorated
particles to aggregate. Using gold nanoparticles (AuNPs) functionalized
with a cysteine-terminated 96-repeat of the VPGVG sequence (V96-Cys),
we show that the size of the clusters that reversibly form above the
ELP transition temperature can be finely controlled in the 250 to
930 nm range by specifying the concentration of free V96-Cys in solution
and using AuNPs of different sizes. We further find that the localized
surface plasmon resonance peak of the embedded AuNPs progressively
red-shifts with cluster size, likely due to an increase in particle–particle
contacts. We exploit this fine control over size to homogeneously
load precise amounts of the dye Nile Red and the antibiotic Tetracycline
into clusters of different hydrodynamic diameters and deliver cargos
near-quantitatively by deconstructing the aggregates below the ELP
transition temperature. Beyond establishing a key role for free ELPs
in the agglomeration of ELP-functionalized particles, our results
provide a path for the thermally controlled delivery of precise quantities
of molecular cargo. This capability might prove useful in combination
photothermal therapies and theranostic applications, and to trigger
spatially and temporally uniform responses from biological, electronic,
or optical systems.