A "turn-on" intracellular pH probe for the quantitative monitoring of lysosomal alkalization in living cells

A slight elevation in lysosomal pH can lead to indigestion or nonspecific hydrolysis, thereby increasing the risk of various neurodegenerative diseases and cancer. Therefore, accurate monitoring of lysosomal pH changes in living cells is essential for the diagnosis and treatment of such diseases, despite the significant challenges involved. In this study, we synthesized a pH-dependent fluorescent probe, B26, which comprises 1,8-naphthalimide as the fluorescent chromophore, an N-(2-hydroxyethyl) piperazine group for lysosome targeting, and a hydroxyethyl group to increase solubility and regulate pKa. B26 demonstrated high sensitivity, selectivity, and reversibility in response to H+, and exhibited a remarkable 98-fold increase in fluorescence intensity between pH 2.0 and pH 11.0, with a pKa value of 7.0, highlighting its "turn-on" fluorescence property. Density functional theory calculations and 1H NMR titration revealed that the pH-sensing mechanism of B26 relies on the inhibition of photoinduced electron transfer from the N-(2-hydroxyethyl) piperazine group to the naphthalimide moiety under acidic conditions. Importantly, B26 effectively labeled lysosomes and displayed significant sensitivity to pH changes, facilitating the quantitative detection of pH shifts during lysosomal alkalization in living cells due to its elevated pKa. These findings suggest that B26 successfully addresses the limitations of existing lysosomal pH probes, particularly in detecting pH changes within the near-neutral range. Furthermore, both the zebrafish model and subcutaneous imaging support the application of B26 in in vivo settings. Given its exceptional properties, B26 holds enormous potential for the research and diagnosis of pH-related diseases.

A Multisynergistic Strategy for Bone Tumor Treatment: Orchestrating Oxidative Stress and Autophagic Flux Inhibition by Environmental-Response Nanoparticle

Tumor therapy has advanced significantly in recent years, but tumor cells can still evade and survive the treatment through various mechanisms. Notably, tumor cells use autophagy to sustain viability by removing impaired mitochondria and clearing excess reactive oxygen species (ROS). In this study, the aim is to amplify intracellular oxidative stress by inhibiting mitochondrial autophagic flux. Multisynergistic environmental-response nanoparticles (ERNs) are engineered by integrating gold nanoparticles and copper peroxide with borosilicate bioactive glass. The controlled release of copper and inhibition of autophagy flux triggered an overabundance and accumulation of oxidative stress within the tumor cells. This stress triggered immunogenic tumor cell death, believed to initiate a systemic immune response. The tumor microenvironment (TME) transitioned back to a normal physiological state as tumor cells are ablated. ERNs responded to the microenvironment changes by depositing hydroxyapatite on the surface and spontaneously enhancing bone regeneration. This innovative formulation facilitates the functional transition of ERNs from "anti-tumor therapy" to "biomineralization" that kills cancers and induces new bone formation. Overall, it is shown that the ERNs effectively eradicate cancers by utilizing chemodynamic therapy, starvation therapy, and immunotherapy.

A dual-emission fluorescence-enhanced probe for hydrogen sulfide and its application in biological imaging

A fluorescence-enhanced probe with unique dual-channel emissions was designed for the detection and bioimaging of hydrogen sulfide.