Zijuan Hai

Although the cancer treatment efficacy has significantly improved, delayed and isolated evaluation methods are difficult to prevent excessive or insufficient treatment. Therefore, the single molecule for simultaneous therapy and feedback has become a promising tool. Herein, we develop an in situ self‐assembled probe (HPO‐CYFF‐TPP) for cascade‐instructed therapy and feedback imaging. Under the dephosphorylation of alkaline phosphatase, HPO‐CYFF‐TPP converts to HO‐CYFF‐TPP and self‐assembles into nanoparticles (NPs) with quenched fluorescent (FL) and opened photoacoustic (PA) signal. After laser irradiation, NPs can produce abundant singlet oxygen for photodynamic therapy (PDT) of tumor cells, which leading to the increase of intracellular viscosity. At high viscosity, NPs opens FL and further enhances PA signal. HPO‐CY‐TPP without self‐assembly group is a control probe. HPO‐CYFF‐TPP or HPO‐CY‐TPP exhibits effective PDT against tumor cells and high tumor inhibition in tumor‐bearing mice, while HPO‐CYFF‐TPP is more effective than HPO‐CY‐TPP due to the formation of NPs in situ. Importantly, HPO‐CYFF‐TPP or HPO‐CY‐TPP can monitor the viscosity during PDT on tumor cells and tumor‐bearing mice for treatment feedback, while HPO‐CYFF‐TPP is more accurate than HPO‐CY‐TPP with higher FL/PA sensitivity. We envision that this self‐assembled probe will be a powerful tool for tumor therapy and real‐time treatment feedback imaging in the future.

Therapeutic peptides have played a huge role in chemotherapy due to their excellent biological activity and biocompatibility. However, therapeutic peptides are vulnerable to enzymatic digestion, which makes them with fast elimination in vivo. Nowadays, peptides self-assembly has become a powerful strategy for constructing nanostructures to boost their stability and bioactivity in vivo. To our knowledge, host-guest interaction-instructed in situ peptides self-assembly for biomedical applications is still rare. Herein, we intended to develop a supramolecular complex (CB[7]-FFYSV) based on the host-guest interactions between cucurbit[7]uril (CB[7]) and N-terminal aromatic residues of a therapeutic peptide (Phe-Phe-Tyr-Ser-Val, FFYSV). CB[7]-FFYSV can release therapeutic peptide FFYSV under the competition of endogenous tumor biomarker spermine (SPM) and then FFYSV can self-assemble in situ with the formation of nanofibers for enhancing tumor treatment. CB[7]-YSV without the self-assembly ability is the control group. The stability of FFYSV was obviously improved under proteinase K after encapsulation by CB[7]. CB[7]-YSV or CB[7]-FFYSV exhibited more significant toxicity to A549 and 4T1 cells with high expression of SPM than YSV or FFYSV. CB[7]-FFYSV is more effective than CB[7]-YSV due to the self-assembly of FFYSV with the formation of dense short nanofibers with an average width of 38.5 ± 12.4 nm and a length of 431.5 ± 63.1 nm in the cytoplasm. However, YSV or FFYSV displayed obvious toxicity while CB[7]-YSV or CB[7]-FFYSV exhibited negligible toxicity to HepG2 cells with low expression of SPM. Furthermore, the SPM-instructed release and subsequent in situ self-assembly of FFYSV enhanced antitumor efficacy of YSV in vivo. We envision that the host-guest interaction-instructed in situ self-assembly will be useful for effective treatment of diseases in the future.

In this study, we developed a mitochondria-targeted near-infrared fluorescent probe HD-Br-D for simultaneous detection of H ₂ S, Cys, and GSH in vitro and in vivo .

Inflammatory bowel disease (IBD) is a chronic and relapsing disease of the gastrointestinal tract. At present, antioxidant therapy is a promising strategy for IBD treatment. Since low-molecular-weight antioxidants (e.g., 2,2,6,6-tetramethylpiperidin-N-oxyl (TEMPO)) have a short in vivo half-life and inadequate cellular uptake, researchers have focused on loading antioxidants into nanostructures for improving their antioxidant and anti-inflammatory activities. As we know, in situ self-assembly with the formation of nanostructures under intracellular specific stimuli is a convenient delivery strategy to enhance the accumulation and retention of molecules at target sites in vivo. Herein, we developed an in situ self-assembled TEMPO probe TPP-FFYp-O to improve the antioxidant and anti-inflammatory effects of TEMPO in IBD. Compared to the control probe TPP-O without a self-assembly moiety, TPP-FFYp-O could successfully self-assemble into nanoparticles (NPs) under alkaline phosphatase (ALP)-guided dephosphorylation, with significantly enhanced antioxidant capacity in vitro. Cell experiments confirmed that intracellular formation of NPs by TPP-FFYp-O could improve the antioxidant and anti-inflammatory abilities of TEMPO and alleviate cellular damage. Moreover, TPP-FFYp-O exhibited good biocompatibility in vivo and significantly relieved pathological injury and inflammatory factors in the colon tissues of an IBD model compared to TPP-O. We envision that the in situ self-assembly platform can be used to load various active molecules for more applications in the future.

Alkaline phosphatase (ALP)-instructed self-assembly of a peptide precursor (NapFFYpLSKL) with the formation of LSKL nanoparticles (NPs) in situ for improving the specific therapeutic effect against liver fibrosis.

In the realm of photodynamic therapy (PDT), the incorporation of real-time feedback through two-photon fluorescence lifetime imaging poses a significant challenge, primarily due to the intricate nature of photosensitizer design. In our investigation, we have effectively constructed a versatile platform labeled as ZTBH using a post-ligand modification approach, resulting in enhanced two-photon fluorescence capabilities and notable responsiveness of fluorescence lifetime to variations in the cellular microenvironment. The distinctive synergy between intersystem crossing and linker-to-cluster charge transfer within ZTBH empowers the generation of ample reactive oxygen species (¹O₂ and O₂˙⁻), thereby yielding remarkable efficiency in PDT. Moreover, the capping of hyaluronic acid (HA) through the coordination method confers cancer-specific targeting properties on ZTBH. Subsequently, with the aid of a two-photon fluorescence lifetime imaging microscope (TP-FLIM), ZTBH not only achieves successful two-photon photodynamic therapy but also enables real-time visualization of cellular microenvironment changes throughout the apoptosis process. This investigation underscores a viable approach for the creation of two-photon fluorescence lifetime photosensitizers for visualizing the PDT procedure.

Chemotherapy is the most commonly used method to treat malignant tumors with a wide range of drugs. However, chemotherapeutic drugs are characterized by poor solubility, low stability and specificity, as well as drug resistance, which led to their limited bioavailability and severe adverse effects. Therefore, most researches focus on one or two strategies while a few researches focus on three strategies to improve the efficacy of drugs. Herein, we combined three strategies (targeted therapy, prodrug design and drug delivery) to exploit a self-assembled camptothecin (CPT) prodrug (CPT-SS-FFEYp-Biotin) for enhancing therapeutic efficacy and reducing side effects of CPT. CPT-SS-FFEYp-Biotin enters into tumor cells following the recognition between biotin and biotin receptors. Moreover, the over-expressed alkaline phosphatase (ALP) on cell membranes specifically dephosphorylates CPT-SS-FFEYp-Biotin to CPT-SS-FFEY-Biotin, which self-assembles into a CPT hydrogel with the local enrichment of CPT. Subsequently, excess glutathione (GSH) in tumor cells can reduce the disulfide bond of CPT-SS-FFEY-Biotin to slowly release CPT for sustained tumor therapy. Cell experiments demonstrated that CPT-SS-FFEYp-Biotin enhances therapeutic efficacy of CPT on tumor cells while being safer to normal cells than CPT. Moreover, CPT-SS-FFEYp-Biotin effectively improved anti-tumor treatment of CPT in vivo. We envision that the integration of these three strategies is helpful to exploit a variety of prodrugs for effective anti-tumor treatment in the future.

Fluoride anions (F^-) play a crucial role in human physiological processes. However, excessive intake of F^- would affect oxygen metabolism and promote the generation of oxygen-free radicals. Hence, it is essential to develop a precise and efficient fluorescent probe for visualizing F^--induced oxidative stress. In this work, we developed the first bifunctional BODIPY-based fluorescent probe dfBDP with p-tert-butyldimethylsilanolate benzyl thioether as the sensing site for the detection of F^- and HClO via two distinct reactions, the self-immolative removal and the thioether oxidation, which generate the sensing products with two nonoverlap fluorescence bands: 800-1200 and 500-750 nm, respectively. The probe dfBDP displays rapid response, high specificity, and sensitivity for the detection of F^- (LOD, 316.2 nM) and HClO (LOD, 33.9 nM) in vitro. Cellular imaging reveals a correlation between F^--induced oxidative stress and the upregulation of HClO. Finally, probe dfBDP was employed to detect F^- and HClO in mice under the stimulation of F^-. The experimental results display that the level of HClO elevates in the liver of mice.

An uncontrolled immune response leads to many diseases; therefore, monitoring inflammation is crucial for the diagnosis of subsequent diseases, drug screening, and targeted therapy. Since the inflammatory response mainly occurs in macrophages, there is a need to develop more inflammatory probes with macrophage-targeting ability. Herein, we designed a macrophage-targeted and hydrogen-peroxide-activated fluorescent probe BOH-HCy-Man for real-time imaging of inflammation in vivo and a control probe BOH-HCy without the macrophage-targeting part. The larger rate constant toward H₂O₂ led to the higher sensitivity of BOH-HCy-Man (19.1-fold) than BOH-HCy (10.2-fold) in vitro. With the help of its macrophage-targeting ability, BOH-HCy-Man possessed an additional 1.6-fold fluorescent enhancement in inflamed RAW 264.7 cells or 1.3-fold fluorescent enhancement in vivo than BOH-HCy. We expected that BOH-HCy-Man will be a powerful tool for early diagnosis of inflammation related diseases.