Genetically
Programmed Clusters of Gold Nanoparticles
for Cancer Cell-Targeted Photothermal Therapy
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Abstract
Interpretations
of the interactions of nanocarriers with biological
cells are often complicated by complex synthesis of materials, broad
size distribution, and heterogeneous surface chemistry. Herein, the
major capsid proteins of an icosahedral T7 phage (55 nm in diameter)
are genetically engineered to display a gold-binding peptide and a
prostate cancer cell-binding peptide in a tandem sequence. The genetically
modified phage attracts gold nanoparticles (AuNPs) to form a cluster
of gold nanoparticles (about 70 nanoparticles per phage). The cluster
of AuNPs maintains cell-targeting functionality and exhibits excellent
dispersion stability in serum. Under a very low light irradiation
(60 mW cm<sup>β2</sup>), only targeted AuNP clusters kill the
prostate cancer cells in minutes (not in other cell types), whereas
neither nontargeted AuNP clusters nor citrate-stabilized AuNPs cause
any significant cell death. The result suggests that the prostate
cancer cell-targeted clusters of AuNPs are targeted to only prostate
cancer cells and, when illuminated, generate local heating to more
efficiently and selectively kill the targeted cancer cells. Our strategy
can be generalized to target other types of cells and assemble other
kinds of nanoparticles for a broad range of applications