Hypoxia
of tumor microenvironments is a major factor restricting
tumor treatment, which causes progression and metastasis of tumor.
The hypoxic tumor microenvironment not only makes the traditional
treatment method, such as chemotherapy, ineffective but also hinders
the O2-dependent treatments, such as photodynamic therapy
(PDT). Recently, stimuli-responsive nitric oxide (NO) donors have
attracted extensive research interest in hypoxic tumor treatment because
the NO release process is O2-independent. Besides, NO can
distribute more uniformly than drug molecules and more widely than
the PDT-generated active species due to its strong diffusion ability
(200 μm in cells) and long lifetime (2 s in cells). Encouraged
by these advantages, a near infrared light-triggered NO release polymeric
nanoplatform (P1-CapNO NPs) was constructed by a thermally
sensitive NO release unit, a photothermal unit, and a hydrophilic
polyethylene glycol unit. P1-CapNO NPs possess strong
absorption in the NIR region (the wavelength of maximal absorption
peak was 790 nm with a molar absorption coefficient of 2.4 ×
105 M–1 cm–1), great
photothermal conversion efficiency (23.8%), and NO release ability
(the released NO concentration can reach 1.3 μM) under 808 nm
laser irradiation. Owing to these advantages, the great synergistic
antitumor effect can be achieved in vitro and in vivo even under the
hypoxic environment. The synergistic therapeutic strategy in this
work could bypass the obstacles caused by hypoxia in tumor treatment
and provide a reference for building a NO-involved therapeutic platform.