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Despite the clinical potential, photodynamic therapy (PDT) relying on singlet oxygen (1O2) generation is severely limited by tumor hypoxia and endosomal entrapment. Herein, a proton‐driven transformable 1O2‐nanotrap (ANBDP NPs) with endosomal escape capability is presented to improve hypoxic tumor PDT. In the acidic endosomal environment, the protonated 1O2‐nanotrap ruptures endosomal membranes via a "proton‐sponge" like effect and undergoes a drastic morphology‐and‐size change from nanocubes (≈94.1 nm in length) to nanospheres (≈12.3 nm in diameter). Simultaneously, anthracenyl boron dipyrromethene‐derived photosensitizer (ANBDP) in nanospheres transforms to its protonated form (ANBDPH) and switches off its charge‐transfer state to achieve amplified 1O2 photogeneration capability. Upon 730 nm photoirradiation, ANBDPH prominently produces 1O2 and traps generated‐1O2 in the anthracene group to form endoperoxide (ANOBDPH). Benefitting from the hypoxia‐tolerant 1O2‐release property of ANOBDPH in the dark, the 1O2‐nanotrap brings about sustained therapeutic effect without further continuous irradiation, thereby achieving remarkable antitumor performance. [ABSTRACT FROM AUTHOR]

Tumor hypoxia severely impedes the therapeutic efficacy of type II photodynamic therapy (PDT) depending on singlet oxygen (1O2) generation. To combat hypoxic tumors, herein, a new approach is devised to boost superoxide radical (O2•−) photogeneration for type I PDT. Heavy atoms are introduced onto aza‐BODIPY molecules (iodine substituted butoxy‐aza‐BODIPY, IBAB) to promote their intersystem‐crossing (ISC) ability. Meanwhile, methoxy‐poly(ethylene glycol)‐b‐poly(2‐(diisopropylamino) ethyl methacrylate) (mPEG‐PPDA) with enhanced electron‐donating efficiency is employed as a coating matrix to encapsulate IBAB, thereby obtaining amphiphilic aza‐BODIPY nanoplatforms (PPIAB NPs). Under irradiation, triplet‐state IBAB in PPIAB NPs is efficiently generated from singlet state favored by the elevated ISC ability. The electron‐rich environment provided by mPEG‐PPDA can donate triplet‐state IBAB with one electron to form charge‐separated‐state IBAB, which in turn transfers electron to O2 for O2•− production. Significantly, owing to recyclable O2 generated by disproportionation or Harber–Weiss/Fenton reaction, prominent O2•− is generated by PPIAB NPs even in a severe hypoxic environment (2% O2), enabling superior therapeutic efficacy (96.2% tumor‐inhibition rate) over NPs not following this strategy. Thus, the proof‐of‐concept design of ISC‐enhanced and electron‐rich polymer encapsulating PPIAB NPs illuminates the path to preparing O2•− photogenerator for hypoxic cancer treatment. [ABSTRACT FROM AUTHOR]

A correction to the article, "Boosting oxygen free-radical (O2•−) Photogeneration via Promoting Intersystem Crossing and Electron-Donating Efficiency of Aza-BODIPYBased Nanoplatforms for Hypoxic-Tumor Photodynamic Therapy" published in the previous issue of the periodical.

Cancer has become a severe threat to human life due to its high mortality and metastatic rate. Effective inhibition and killing of cancer cells using chemotherapeutic drugs have been a promising means in clinical cancer therapy. However, the low selectivity, drug-resistance, uncontrollability and serious side effects of chemotherapy significantly limit its further development. There is an urgent need for new treatment strategies to compensate for deficiencies inherent in chemotherapy alone. A growing body of research shows that combined treatment strategies have the potential to overcome this dilemma by achieving significantly enhanced synergistic effects and reduced side effects. Emerging phase change materials (PCMs) create an ideal nanoplatform for cancer combination therapy due to their universal loading properties, stable and temperature-responsive phase transition capability, and excellent natural biocompatibility/biodegradability. The release of therapeutic agents can be precisely controlled through external, non-intrusive stimuli (such as NIR light and ultrasound), avoiding systemic toxicity associated with conventional chemotherapy. Herein, the construction methods and design principles of PCM-based nanoplatforms serving as strict gatekeeper and smart payload delivery systems are discussed in detail. Moreover, the advantages and disadvantages of these nanoplatforms are provided. A suitable discussion and perspective of the remaining challenges and future opportunities for PCM-based nanoplatforms in cancer treatment are also given in conclusion., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Chemodynamic therapy (CDT), employing Fenton or Fenton-like catalysts to convert hydrogen peroxide (H 2 O 2 ) into toxic hydroxyl radicals (˙OH) to kill cancer cells, holds high promise in tumor therapy due to its high selectivity. However, the anticancer efficacy is unsatisfactory owing to the limited concentration of endogenous H 2 O 2 . Herein, thermal responsive nanoparticles with H 2 O 2 self-sufficiency are fabricated by utilizing organic phase change materials (PCMs) to encapsulate iron-gallic acid nanoparticles (Fe-GA) and ultra-small CaO 2 . PCMs, acting as the gatekeeper, could be melted down by the hyperthermia effect of Fe-GA under laser irradiation with a burst release of Fe-GA and CaO 2 . The acidic tumor microenvironment would further trigger CaO 2 to generate a large amount of H 2 O 2 and Ca 2+ . The self-supplied H 2 O 2 would be converted into ˙OH by participating in the Fenton reaction with Fe-GA. Meanwhile, in situ generation of Ca 2+ could cause mitochondrial damage and lead to apoptosis of tumor cells. With efficient tumor accumulation illustrated in in vivo photoacoustic imaging, Fe-GA/CaO 2 @PCM demonstrated a superior in vivo tumor-suppressive effect without inducing systemic toxicity. The study presents a unique domino effect approach of PCM based nanoparticles with thermal responsiveness, H 2 O 2 self-supply, and greatly enhanced CDT effects, showing bright prospects for highly efficient tumor treatment., Competing Interests: There are no conflicts of interest to declare., (This journal is © The Royal Society of Chemistry.)