b2815 Tissue Engineering and Nanotheranostics “9.61x6.69”
180 Tissue Engineering and Nanotheranostics
apoptosis. Following that, a detailed work on concentrationdependent
has been done. They found that cancer cell communities have cellular
attraction, clustering, and bystander killing at low concentrations,
while the degree of attraction and clustering is diminished and most
cells in community died at high nanoparticle concentrations.
6. Other Application
Besides the nanoparticle’s plasmic property, its optical property, such
as Förster resonance energy transfer (FRET), surface enhanced Raman
scattering (SERs) and nonlinear optical properties, also have been
applied to construct biosensors for biosensing and bioimaging. For
example, with the help of its high surface area to volume ratio, a serial
of biomolecules and biomarkers can be conjugated to a nanoparticle,
constructing a multifunction probe for detecting various material,
ranging from small organic molecules to proteins.
6.1. Energy Transfer
FRET technology is widely applied in detecting dynamic changes at
single molecule level. The nonradiative transfer of excitation energy
between donor and acceptor interacts by dipole–dipole when dis
tance between them is smaller than the Förster distance (typically
less than 10 nm).159,160 To trigger FRET, the emission frequency of
the donor should match the absorption frequency of the
acceptor.161–163 Due to their large molar extinction coefficients,
AuNPs can be used as acceptors to quench the donors.^164 When
metal nanoparticles are used as acceptors, the energy transfer phe
nomenon is named NSET. While AuNPs also can be used as a donor
to be quenched by absorbed molecular acceptors this energy transfer
form is named as PRET.^165
6.1.1. Plasmon resonance energy transfer
When the plasmon resonance spectrum of a plasmon sensor inten
tionally matches the absorption spectrum of chemical or biological
