Sonodynamic therapy as a promising noninvasive modality is being developed for tumor therapy, but there is a lack of next‐generation sonosensitizers that can generate full ROS at high yields and simultaneously deplete elevated levels of glutathione (GSH) in tumor cells. Semiconductor p‐n junctions are engineered as high‐efficacy sonosensitizers for sonodynamic tumor eradication using pyridine N‐doped carbon dots (N‐CDs) as a p‐type semiconductor and oxygen‐deficient TiO2−x nanosheets as a n‐type semiconductor. The rate constants of 1O2 and •OH generation by ultrasound‐excited N‐CD@TiO2−x p‐n junctions are 4.3 and 4.5 times higher than those of TiO2, respectively. A Z‐scheme carrier migration mechanism in the p‐n junction achieving the rapid spatial separation of the ultrasound‐generated electron–hole pairs for enhanced full ROS production is proposed. GSH‐cleavable, Pt‐crosslinked, N‐doped CD fluorescent probes to detect the presence of intracellular GSH are also constructed. A GSH‐responsive, p‐n junction platform (Pt/N‐CD@TiO2−x) with integrated GSH detection, GSH depletion, and enhanced sonodynamic performance is then assembled. Malignant tumors are completely eradicated without relapse via intravenous administration of low‐dose Pt/N‐CD@TiO2−x under ultrasound irradiation. This work substantiates the great potential of biocompatible, GSH‐responsive p‐n junctions as next‐generation sonosensitizers via p‐n junction‐enhanced ROS generation and metal ion oxidation of intracellular GSH.
Photodynamic therapy (PDT) as a rising
platform of the cancer treatment
method is receiving increased attention. Through systematic evaluation
of halogen substitution on aza-4,4-difluoro-4-bora-3a,4a-diaza-s-indacenes (BODIPY),
we have found that monoiodo-derived aza-BODIPYs provided greater efficacy
than other halogenated aza-BODIPY PSs. 4 and 15 as monoiodinated aza-BODIPY dyes containing p-methoxyphenyl
moiety were identified to be potent NIR aza-BODIPY-type PSs with IC50 values against HeLa cells at a light dose of 54 J/cm2 as low as 76 and 81 nM, respectively. 4 possessed
superior phototoxicity, low dark toxicity, and good thermal/photostability
and distributed majorly in mitochondria in cells. Apoptosis was verified
to be the main cell death pathway, and in vitro reactive oxygen species
generation was demonstrated. In vivo whole-body fluorescence imaging
and ex vivo organ distribution studies suggested that 4 afforded an excellent PDT effect with a low drug dose under single-time
light irradiation and revealed advantages over known PSs of ADPM06 and Ce6.
Fluorescent dyes are extensively
utilized in various fluorescence
imaging techniques. However, many existing modification strategies
could not balance the performance (such as brightness, photostability,
water solubility, and permeability) of fluorophores. Herein we report
a general strategy to enhance the performance of donor–acceptor-type
fluorophores by introducing azetidine-containing heterospirocycles
to the commonly used fluorophore scaffolds. Such a strategy turned
out to be a general way to develop high-quality fluorophores.
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