Chiral Induced Highly Efficient NIR-Photothermal Conversion of Perylene
Diimide@Silica Nanocapsules for Photothermal Therapy
Abstract
Photothermal agents (PTAs) with ultra-high photothermal conversion
efficiency (PCE) activated upon near-infrared (NIR) laser irradiation
can heat up and destroy tumor cells under low-intensity laser excitation
to allow safe and efficient tumor therapy. Herein, an organic PTA with
outstanding PCE of 89.6% is developed from rationally designed perylene
diimide (PDI) with electron donating cyclohexylamine moiety at the
bay-positions of its skeleton and chiral phenethylamine (PEA) moiety at
its N terminals, termed here as PEAPDI. The strong intermolecular
interaction between the PDI skeletons induced by PEA together with the
intramolecular charge transfer from cyclohexylamine to PDI skeleton
severely quenches the fluorescence emission from PEAPDI and
significantly enhance its NIR absorption, resulting in super
NIR-photothermal conversion. PEAPDI is further encapsulated into silica
nanocapsules (SNC) to produce PEAPDI@SNC. The specific features of
PEAPDI@SNC, including small hydrodynamic diameter with monodispersity,
high PDI encapsulation efficiency, colloidal stability and
biocompatibility, effectively extend its blood circulation time and
enhance its permeability and retention effect to accumulate at the tumor
site. In vivo study using a 4T1-tumor-bearing mice model
demonstrates highly effective tumor ablation without side effect at low
dosage of PEAPDI@SNC with NIR laser irradiation (808 nm). PEAPDI@SNC
shows great potential for photothermal therapy in tumor treatment.