Photothermal
therapy (PTT) as a single treatment still faces a
challenge in completely eradicating deep tumors due to the limited
tissue penetration of light. The combination of PTT and chemotherapy
could effectively improve the therapeutic effect. Herein, we report
a prodrug-hemicyanine conjugate (Cy-azo) to achieve H-aggregation
improved photothermal therapy and sequential hypoxia-activated chemotherapy.
Due to the introduction of the chemotherapeutic drug, nitrogen mustard,
Cy-azo demonstrates high photothermal conversion efficiency (PCE,
39.3%) caused by the enhanced H-aggregation of the prodrug through
π–π stacking. Moreover, the activated drug is released
in the tumor hypoxic microenvironment, which can kill cancer cells
and greatly reduce the toxic side effects of chemotherapy. In addition,
Cy-azo is further encapsulated into polymer nanoparticles to stabilize
the Cy-azo H-aggregates and increase the tumor accumulation of Cy-azo
through the enhanced permeability and retention effect (EPR). Interestingly,
Cy-azo NPs show an enhanced PCE as 56.1% and demonstrate an excellent
anticancer therapeutic effect under 808 nm light irradiation. The
combination of PTT with hypoxia-activated chemotherapy is promising
for anticancer treatment and would guide future development of prodrugs
for combined PTT and chemotherapy.
Small interfering RNA (siRNA) holds immense promise for suppressing gene expression and treating various life‐threatening diseases, including cancer. However, efficient delivery and lysosomal escape remain critical challenges that hinder the therapeutic effectiveness of siRNA. Herein, cationic photosensitizer (NB‐Br) is grafted onto polo‐like kinase 1 (PLK1) siRNA to form an amphiphilic siRNA‐photosensitizer conjugate (siPLK1‐NB), which can self‐assemble into nanoparticles (siPLK1‐NB NPs) via electrostatic attraction. Notably, siPLK1‐NB NPs exhibit rapid and efficient cell endocytosis, as well as outstanding tumor‐targeting property in multiple tumor‐bearing mice models. When siPLK1‐NB NPs are located inside tumor cell lysosomes, the generated reactive oxygen species (ROS) after photoactivation can disrupt the lysosome membrane structure and facilitate siRNA escape from lysosomes. Under light irradiation, siPLK1‐NB NPs can downregulate PLK1 expression and induce photodynamic killing, effectively inhibiting tumor cell growth both in vitro and in vivo. Consequently, this study provides a novel design strategy for carrier‐free siRNA delivery systems. As far as it is known, this is the first report of a carrier‐free siRNA delivery system based on electrostatic attraction.
Removal
of particulates in slurry oil (SO) from the fluid catalytic
cracking process is a challenging task in refining. In this study,
we investigate the intrinsic characteristics of particulates in SO
and the effect of thermal treatment on their flocculation and further
separation. The particulates in SO were characterized by scanning
electron microscopy, energy-dispersive X-ray spectroscopy, Fourier
transform infrared spectroscopy, etc. Results show that the particulates
in SO are composed of coke powders and catalyst powders coated with
coke species, with diameters of approximately 1 μm dominating
the particle size distribution. The solid contents of middle fractions
depend upon thermal treating severities. The particulates are originally
dispersed in SO, whereas flocculation of particulates is observed
after thermal treatment. A negative linear correlation is found between
the solid contents of middle fractions and the asphaltene contents
of thermally treated SOs under different thermal treating severities.
The mechanism of particle growth as a result of flocculation of particulates
with asphaltenes, which favors efficient removal of particulates,
is proposed.
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