English

• As the main health burden for humankind worldwide, cancer has caused almost tens of thousands of deaths every year [1, 2]. The development of efficient diagnosis and treatment modalities against cancer has become increasingly urgent and essential. As a clinically approved protocol for cancer phototheranostics, fluorescence imaging-guided photodynamic therapy (FLI-guided PDT) has garnered considerable interest because of its distinct advantages, including non-invasiveness, controllability, and negligible drug resistance [3-5]. Viewed in FLI-guided PDT, the photosensitizers (PSs) can generate cytotoxic reactive oxygen (ROS) upon exposure to light irradiation, which can eradicate tumor cells [6-9]. In addition, the emission ability of designed PSs can enable FLI, achieving real-time monitoring of tumor tissue. Generally, concerted efforts have been devoted to designing PSs with strong light absorption, high emission efficiency, and high ROS sensitization capacity for FLI-guided PDT. In PDT, the PSs can undergo type Ⅰ or type Ⅱ photochemical reactions to produce toxic radicals (superoxide anion O₂^•−, hydroxyl radical ^•OH, etc.) or singlet oxygen (¹O₂), respectively [10]. Type Ⅱ PDT depends on oxygen concentration in the surrounding microenvironment, which compromises the therapeutic efficacy in hypoxic solid tumors [11]. Different from type Ⅱ PDT, type Ⅰ PDT shows more promise for deactivating the solid tumors owing to the oxygen-less-dependent path [12-15]. However, classical PSs work through type Ⅱ photosensitization because of the much faster process of type Ⅱ than type Ⅰ. Constructing advanced PSs capable of generating type Ⅰ/Ⅱ ROS is an effective approach for enhancing PDT efficacy and eliminating tumors [16, 17].

  Organic PSs have been investigated and applied in FLI-guided PDT broadly owing to low toxicity, well-definite composition, good biocompatibility, and facile molecular tailoring [18, 19]. However, the conventional organic PSs with the planar hydrophobic molecular skeleton tend to aggregate in biological environments, leading to a drastic decrease in both emission efficiency and photosensitivity [20]. To address these challenges, the construction of PSs with aggregation-induced emission (AIE) nature emerges as a promising strategy [21-25]. AIE-active PSs exhibit brighter emission and enhanced ROS generation in the aggregate state [26-28]. Considering the advantages of near-infrared (NIR) light such as deep penetration and reduced interference with tissue photodamage, the concise development of AIE-active PSs with NIR emission holds tremendous promise for boosting FLI-guided PDT efficiency [29-32]. Generally, donor-π-acceptor (D-π-A) molecular engineering has been widely employed to construct AIE PSs [33, 34]. This molecular design strategy is beneficial for narrowing singlet-triplet energy gaps, thus enhancing the intersystem crossing (ISC) process and achieving efficient ROS production [35, 36]. Despite significant progress has been made in developing AIE PSs for FLI-guided PDT application, there is a deficiency in constructing AIE-based PSs capable of efficient NIR fluorescence and excellent type Ⅰ/Ⅱ ROS generation. The new design strategy and clear structure-property is also desired.

  To achieve good anticancer performance, in this work, two appealing PSs named TPCPY and TFCPY were designed and synthesized by the integration of electron-withdrawing and electron-donating units on different π bridges, as shown in Scheme 1. The impact of π bridges in the D-π-A molecular skeleton on curative effect was investigated systematically. Selecting an electron-rich furan group as π-bridge rather than a phenyl unit enables TFCPY with red-shifted absorption, enhanced molar absorption coefficient, and NIR emission. Both compounds were demonstrated to possess superior ROS generation ability than commercially available Rose Bengal (RB) as well as chlorin e6 (Ce6). Moreover, TPCPY and TFCPY can produce ¹O₂, O₂^•−, and ^•OH simultaneously, displaying type Ⅰ/Ⅱ combined PDT capability. TFCPY with furan π-bridge exhibited relatively higher type Ⅰ ROS compared with that of TPCPY, which can be attributed to a smaller energy gap (0.08 eV) between first singlet excited state (S₁) and 2^nd triplet excited states (T₂). Subsequently, intracellular experiments demonstrated that TFCPY performed superior cellular imaging, ROS generation capability, and prominent anti-cancer cell ability contrasted with TPCPY. Furthermore, in vivo PDT results reveal that TFCPY effectively achieves fluorescence imaging and inhibits tumor growth.

  Scheme 1

  

  Scheme 1.  Schematic illustration of π bridge engineering of TPCPY and TFCPY, and FLI-guided PDT.

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  To systematically study the effect of π-conjugation bridge engineering in regulating the photoluminescence (PL) properties and ROS generation ability, two compounds were rationally designed with D-π-A molecular skeleton, in which phenyl and furan ring was used as π-conjugation bridge for TPCPY and TFCPY, respectively (Scheme 1). Considering rich electron characteristics and twisted structure, the triphenylamine (TPA) group served as the electron donor (D) and molecular rotor. Cationic methylpyridinium with cyano moiety acted as the electron acceptor (A). The D and A units were integrated by different π-bridge to construct D-π-A-type molecules. The designed photosensitizers TPCPY and TFCPY were prepared simply through the synthetic route outlined in Scheme S1 (Supporting information). The electron-donating TPA and π-bridge were connected by the Suzuki-Miyaura coupling reaction. Then, the intermediates TP-CHO and TF-CHO were reacted with pyridylacetonitrile hydrochloride through a Knoevenagel condensation reaction. Detailed synthesis and characterization (Figs. S1–S12 in Supporting information) data are found in Supporting information.

  The photophysical properties of TPCPY and TFCPY were analyzed by ultraviolet–visible (UV–vis) absorption spectra. As presented in Fig. 1A, both compounds showed typical intramolecular charge transfer (ICT) absorption profiles in dimethylsulfoxide (DMSO) solutions with broad bands from 400 nm to 700 nm. With electron-rich heterocyclic furan in the molecular skeleton, the maximal absorption wavelength of TFCPY (544 nm) featured a remarkable bathochromic shift with an absorption tail toward the near-infrared region in comparison with TPCPY (470 nm). The ICT character was further confirmed by solvatochromic effect (Fig. S13 in Supporting information). Noteworthy, the maximum molar absorption coefficient of TFCPY (3.07 × 10⁵ L mol⁻¹ cm⁻¹) is much higher than that of TPCPY (1.78 × 10⁵ L mol⁻¹ cm⁻¹), being favorable for capturing more excitation light [37, 38]. To investigate the emission properties in aggregate, the PL spectra of TPCPY and TFCPY were recorded in a DMSO/toluene mixture. As illustrated in Fig. 1B and Fig. S14 (Supporting information), upon enhancing toluene fractions (ƒ_T), the emission intensities were significantly increased due to the formation of aggregate. The PL intensity increase of TPCPY and TFCPY at 95% of toluene contents was about 15- and 17-fold higher than those in their pure DMSO solutions (Fig. 1C). As a consequence, both TPCPY and TFCPY exhibited good AIE characteristics. Both compounds displayed obvious hypochromic shift with increasing toluene fraction, which can be assigned to the solvatochromic effect of typical PSs with ICT characteristics [39-42]. The maximum emission of TPCPY and TFCPY aggregates are at 724 and 725 nm with the fluorescence quantum yields (Ф_F) of 1.2% and 1.1%, and their lifetimes are 2.04 and 2.57 ns, respectively (Fig. S15 in Supporting information). Meanwhile, TFCPY shown obvious emission signal in cell culture media DMEM solution compared with that of TPCPY (Fig. S16 in Supporting information). In addition, TPCPY and TFCPY exhibited excellent photostability (Fig. S17 in Supporting information). The specific photophysical data are summarized in Table S1 (Supporting information). Dynamic light scattering (DLS) analysis confirmed the formation of nanoaggregates of 2 µmol/L TPCPY and TFCPY in a DMSO/H₂O (v: v, 1:99) mixture with an average diameter of 141.8 and 105.7 nm, respectively (Fig. 1D). The transmission electron microscopy (TEM) images inserted in Fig. 1D showed different morphologies of nanoaggregates, indicating that different π-bridge can have an important influence on the aggregation behavior. All compounds in aggregate state possessed the negatively charged surface with a zeta potential of −8.43 and −8.48 mV for TPCPY and TFCPY, respectively (Fig. 1E).

  Figure 1

  

  Figure 1.  (A) The absorption spectra of TPCPY and TFCPY in DMSO solutions (10 µmol/L). (B) Photoluminescence (PL) spectra of TFCPY (5 × 10⁻⁵ mol/L) in DMSO/toluene mixtures with different toluene fractions (λ_ex: 510 nm). (C) Plots of relative PL intensity (I/I₀) versus the composition of different solution mixtures of designed PSs. (D) The particle size distribution of both PSs detected from DLS (Insert: TEM images, scale bar: 200 nm). (E) Zeta potential of TPCPY and TFCPY. (F) Optimized molecular structures, (G) HOMO-LUMO distribution, and (H) energy level diagrams and SOC values of excited singlet and triplet states for TPCPY and TFCPY (isocontour value = 0.2).

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  Furthermore, the theoretical calculations were conducted to better understand the molecular configurations and electronic properties of TPCPY and TFCPY. As shown in Fig. 1F, the electron-withdrawing unit and π-conjugation bridge in these two compounds exhibit relatively coplanar configurations with small dihedral angles (< 1°). The electron-donating unit is highly twisted structure, which is advantageous for achieving AIE nature. Incorporating furan unit as a π-bridge, TFCPY exhibited a V-shaped structure instead of the linear structure of TPCPY. As shown in Fig. 1G, both compounds possess similar electron cloud distribution. The highest occupied molecular orbitals (HOMOs) distributions were mostly on the whole molecules, whereas the lowest unoccupied molecular orbitals (LUMOs) mainly located on the electron-withdrawing part and π-bridge unit and slightly delocalized on the electron-donating groups. The results indicate that both compounds have an efficient ICT effect. The energy difference (ΔE_ST) and spin-orbital coupling (SOC) are primary factors in determining the ISC efficiency, further impacting ROS generation efficacy [43]. The ΔE_ST between the S₁ and T₁ of TPCPY and TFCPY are calculated to be 0.80 and 0.87 eV, respectively (Fig. 1H). The large energy gaps result in low ISC, which is confirmed by the calculated low SOC constant (ξ) of 0.16 and 0.25 cm⁻¹ for TPCPY and TFCPY. Although similar ξ for TPCPY (0.60 cm⁻¹) and TFCPY (0.56 cm⁻¹), the energy gap between S₁ and T₂ was determined to be 0.08 eV for TFCPY, which is smaller than that of TPCPY (0.43 eV). Thus, an efficient ISC process could occur from S₁ to T₂, which endows TFCPY with better photosensitization functionality than TPCPY.

  To evaluate the impact of π-bridge on PDT performance, the overall ROS production capability of TPCPY and TFCPY were investigated with classic indicator dichlorofluorescein (DCFH). DCFH alone is nearly nonfluorescent and would be activated by any type of ROS to increase its emission intensity. As illustrated in Fig. 2A and Fig. S18 (Supporting information), the emission intensity of DCFH solution coupled with TPCPY or TFCPY increased rapidly with the irradiation time prolonged, compared with the DCFH solution without any photosensitizers, demonstrating excellent ROS generation of both compounds post-irradiation. In comparison, efficient and fast ROS production was achieved by TFCPY, which surpassed TPCPY and clinical PSs including Ce6 and RB. The obtained results suggested that introducing furan ring into TFCPY can exhibit superior capability for ROS generation, which is in accordance with smaller ΔE_ST of TFCPY and moderate SOC value, both leading to better ISC efficiency.

  Figure 2

  

  Figure 2.  ROS generation capability of TPCPY or TFCPY evaluated by different indicators under irradiation (white light, 42 mW/cm²). (A) The relative fluorescence intensity (Ⅰ/Ⅰ₀) of DCFH solution at 524 nm containing PSs versus the irradiation time (DCFH: 40 µmol/L, photosensitizers: 2 µmol/L). (B) The decomposition rates of ABDA at 378 nm absorbance in the presence of PSs (ABDA: 100 µmol/L, photosensitizers: 20 µmol/L). (C) Time-course plots activation rates of DHR123 solution containing PSs with different irradiation time (DHR123: 5 µmol/L, photosensitizers: 2 µmol/L). (D) The relative fluorescence intensity (Ⅰ/Ⅰ₀) of HPF solution containing PSs versus the irradiation time (HPF: 5 µmol/L, PSs: 2 µmol/L).

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  To further explore the ROS species generated by TPCPY and TFCPY, an indicator of 9, 10-anthracene-bis(methylene)dimalonic acid (ABDA) was utilized to verify the formation of ¹O₂. As shown in Fig. 2B and Fig. S19 (Supporting information), the ABDA solutions exhibited a sharp reduction of absorption signal in the system containing TPCPY or TFCPY upon light irradiation. The 82% and 65% of ABDA were consumed by TPCPY and TFCPY as the irradiation time extended to 60 s, indicating that TPCPY produced ¹O₂ more efficiently than TFCPY. Moreover, dihydrorhodamine 123 (DHR123) and hydroxyphenyl fluorescein (HPF) were employed to determine the effectiveness of O₂^•− and ^•OH production, respectively. As shown in Fig. 2C and Fig. S20 (Supporting information), both TPCPY and TFCPY expressed apparent enhancement of 23-fold and 28-fold in emission with extended irradiation exposure time, respectively. In addition, with the auxiliary effect of vitamin C, a widely used radical scavenger, the DHR123 fluorescence increment was quenched, further validating free radical-dominated ROS generation ability. Similar detection results were obtained for HPF (Fig. 2D and Fig. S21 in Supporting information). The gradual increase in the characteristic emission of HPF with prolonged irradiation was detected for both compounds. After 60 s irradiation, the fluorescence intensity of HPF reached 56- and 113-fold for TPCPY and TFCPY, respectively, while more significant enhancement could be discovered in TFCPY. All these results demonstrated that two PSs can effectively generate type Ⅰ/Ⅱ ROS, while the production efficiency of type Ⅰ ROS was found to be higher in TFCPY compared to TPCPY, owing to the strategic incorporation of electron-rich furan ring [44, 45].

  Considering the remarkable type Ⅰ/Ⅱ ROS production and NIR emission properties of TPCPY and TFCPY, their antitumor efficacy was examined in vitro. As the important factor for FLI-guided PDT performance, the cell uptake capability of both compounds was first assessed by confocal laser scanning microscopy (CLSM) with HeLa cells. The HeLa cells were incubated with both compounds for different concentrations and periods. As displayed in Fig. S22 (Supporting information), the apparent fluorescence signal was observed in cells after incubation with a 0.5 µmol/L concentration of TFCPY, then a gradual increase with various TFCPY concentrations ranging from 0 to 5 µmol/L, demonstrating excellent cell penetration and fluorescence imaging ability. As shown in Fig. S23 (Supporting information), the fluorescence intensity was enhanced by prolonging the incubation time. After 30 min, the red fluorescence reached its maximum intensity, indicating that TFCPY could be rapidly incubated by HeLa cells. By contrast, CLSM images revealed that negligible fluorescence signals can be detectable in HeLa cells after incubating with TPCPY in the internalization experiment. These results are probably due to various molecular packing arrangements influenced by different π-bridge. Next, the mitochondrial-targeting behavior of TFCPY was studied by colocalization experiment. The images of HeLa cells in Fig. S24 (Supporting information) demonstrated that TFCPY can efficiently target mitochondria, as its emission signals overlapped with that of Mitotracker Green probes (Pearson correlation coefficient: 0.94). The subcellular distribution of TFCPY could boost its cytotoxicity in PDT.

  Based on efficient cellular internalization and mitochondrial-accumulating, the intracellular ROS generation of both compounds was characterized in HeLa cells using DCFH-DA assay. As illustrated in Fig. 3A, bright green fluorescence was detected in cells treated with TFCPY and DCFH-DA after irradiation, while cells cultured with TPCPY and DCFH-DA exhibited no significant fluorescence at the same experiment condition. The obtained results indicated that TFCPY was able to trigger intracellular ROS generation under light irradiation. Subsequently, phototoxicities of TPCPY and TFCPY were further verified via standard cell counting kit-8 (CCK8) assay. As the results shown in Figs. 3B and C, TPCPY exhibited negligible cytotoxicity at different concentrations with or without white light irradiation. In sharp contrast, the cell killing effect was positively correlated with the concentration of TFCPY. After white light irradiation, TFCPY induced death to over 70% of HeLa cells at the concentration of 5 µmol/L, indicating a good photodynamic killing effect on cancer cells. In addition, the survival rate of HeLa cells in dark was 89%, indicative of dark cytotoxicities to some degree. Additionally, to visualize the PDT efficacy of TPCPY and TFCPY, fluorescein diacetate (FDA) and propidium iodide (PI) were employed to monitor live and dead cells, respectively. As illustrated in Figs. 3D and E, red fluorescence from PI could be observed in the cells treated by both TFCPY and light irradiation, while the green fluorescence almost vanished, indicating the exceptional tumoricaidal efficacy in vitro. However, only a green fluorescence signal can be observed in cells treated with TPCPY. The FDA/PI co-staining results are consistent with the ROS generation ability in HeLa cells.

  Figure 3

  

  Figure 3.  (A) Intracellular ROS detection by DCFH-DA in HeLa cells treated with TPCPY and TFCPY under white light irradiation. Scale bar: 50 µm (top) and 100 µm (bottom). (B) Dose-dependent cytotoxicity of TPCPY to HeLa cells. (C) Dose-dependent cytotoxicity of TFCPY to HeLa cells. Data are presented as mean ± standard deviation (SD) (n = 3). (D) Live/dead cells imaging of HeLa cells stained with FDA/PI after incubation with TFCPY under white light irradiation. Scale bar: 50 µm. (E) Live/dead cells imaging of HeLa cells stained with FDA/PI (FDA: 1 mg/mL, PI: 100 mg/mL) after incubation with TFCPY under white light irradiation for 20 min (42 mW/cm²). Scale bar: 50 µm.

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  Since TFCPY exhibited excellent performance on cellular imaging and ablation, the in vivo FLI-guided PDT antitumor effect was further verified by the mouse model bearing the 4T1 tumor. All the animal experiments were performed according to the guidelines of ethical review of animal welfare, and supervised by Changchun Institute of Applied Chemistry, CAS, China (IACUC Issue No. CIAC 2023. 0174). To check the imaging performance and appropriate incubation time, the fluorescence imaging experiments were carried out at different time points after intratumor injection. As illustrated in Fig. 4B, time-dependent increments in fluorescence intensity in tumor regions were observed, which could be assigned to the gradual diffusion and penetration of TFCPY. At 4 h postinjection, the emission signal reached the maximum level, and the tumor sections could be distinctly distinguished from surrounding tissues, laying the foundation for FLI-guided PDT. Moreover, the fluorescence emission kept intense with 12 h. Furthermore, the therapeutic capability of TFCPY in vivo on mice with the 4T1 tumor was investigated. The four groups of mice (n = 4) underwent the corresponding treatment as follow: (i) phosphate buffered saline (PBS), (ii) PBS with light irradiation, (iii) TFCPY group, (iv) TFCPY with light irradiation. The detailed phototherapy process was illustrated in Fig. 4A. The white light irradiation was conducted for PDT at 4 h on the basis of in vivo fluorescence imaging results. The volumes of the tumors in the four groups were recorded every two days to evaluate the therapeutic outcomes. The tumor growth curves demonstrated that the tumors in the control group i-iii manifested rapid and sustained growth with no significant inhibition, which demonstrated that neither the TFCPY nor white light irradiation could kill the tumor cells (Fig. 4C). In sharp contrast, TFCPY under white light irradiation notably inhibited the tumor volume throughout the entire treatment period. The representative mice photographs (Fig. S25 in Supporting information), extracted tumor images (Fig. 4D), and the mean weight of tumor tissue (Fig. 4E) further intuitively confirmed the excellent PDT tumor-inhibition efficacy of TFCPY under light irradiation. As shown in Fig. S26 (Supporting information), no obvious differences in body weights were found in all groups during the entire treatment process, indicating low systemic toxicity of TFCPY. In addition, hematoxylin and eosin (H & E) staining and immunofluorescence staining of tumor sections of each group were performed to assess the therapeutic effect in vivo. Significant morphological damage was observed in H & E images of the group treated with the TFCPY and white light irradiation, indicating severe tumor necrosis (Fig. 4F). The results from terminal deoxynucleotidyl transferase dUTP nick endlabeling (TUNEL) staining displayed obvious green fluorescence signals in tumor sections from TFCPY-treated group, suggesting significant cell death resulting from TFCPY-based PDT. Consequently, all these results strongly verified that TFCPY exhibited superior fluorescence imaging and therapeutic efficacy, making it competent for cancer phototheranostics.

  Figure 4

  

  Figure 4.  In vivo antitumor capacity of TFCPY in 4T1 tumor-bearing mice model. (A) Schematic diagram of establishing tumor models and in vivo therapeutic process. (B) The fluorescence imaging after intratumor injection of TFCPY with 48 h. (C) The tumor growth curves of different treatment groups. (D) Photograph of tumor sections collected from different treatment groups. (E) The tumor tissue weights from the sacrificed mice. Data are presented as mean ± SD (n = 4). ***P < 0.001. (F) H & E and TUNEL staining of tumor tissues with different treatments (light treatment conditions (+L): irradiation by white light, 100 mW/cm²).

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  In this work, to achieve enhancement of FLI-guided PDT efficacy, two novel D-π-A-structured of TPCPY and TFCPY have been constructed by integration of phenyl and furan ring as a π-bridge, respectively. Both compounds exhibit AIE properties and highly efficient generation of type-Ⅰ and type-Ⅱ ROS upon irradiation. The electron-rich furan ring introduced into TFCPY has proved to bring both a smaller energy gap (0.08 eV) and moderate SOC value (0.56 cm⁻¹) between S₁ and T₂, which is favorable for more efficient ISC process and ROS generation. Therefore, compared with TPCPY, TFCPY exhibits higher ROS generation and more efficient PDT killing outcomes against cancer cells under white-light irradiation. In addition, TFCPY possesses mitochondria targeting capability. Moreover, in vivo experiments indicated that TFCPY can achieve visualization of tumor sites and in the meantime can effectively eliminate tumors in a PDT manner. All these results indicate the excellent FLI-guided PDT efficacy of TFCPY in inhibiting tumor growth and imply that our design of incorporation of furan π bridge into molecular structure could enhance ROS generation and PDT efficacy.

  Declaration of competing interest

  The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

  CRediT authorship contribution statement

  Tong-Tong Zhou: Writing – original draft, Data curation. Guan-Yu Ding: Investigation, Formal analysis, Data curation. Xue Li: Visualization, Validation. Li-Li Wen: Writing – review & editing, Funding acquisition. Xiao-Xu Pang: Formal analysis. Ying-Chen Duan: Methodology. Ju-Yang He: Validation. Guo-Gang Shan: Writing – review & editing, Funding acquisition. Zhong-Min Su: Writing – review & editing.

  Acknowledgments

  This work was supported by the funding from Natural Science Foundation of Jilin Province (No. 20220101191JC), National Natural Science Foundation of China (No. 22175033), and the 13^th Five-Year Program for Science and Technology of Education Department of Jilin Province (No. JJKH20230800KJ).

  Supplementary materials

  Supplementary material associated with this article can be found, in the online version, at doi:10.1016/j.cclet.2024.110341.

  
  
• 1. [1]

     C. Holohan, S. Van Schaeybroeck, D.B. Longley, P.G. Johnston, Nat. Rev. Cancer 13 (2013) 714-726. doi: 10.1038/nrc3599

  2. [2]

     F. Bray, J. Ferlay, I. Soerjomataram, et al., Cancer J. Clin. 68 (2018) 394-424. doi: 10.3322/caac.21492

  3. [3]

     X. Yang, X. Zhang, Z. Yang, et al., ACS Appl. Mater. Interfaces 16 (2024) 9816-9825. doi: 10.1021/acsami.3c17723

  4. [4]

     H. Zhao, N. Li, C. Ma, et al., Chin. Chem. Lett. 34 (2023) 107699. doi: 10.1016/j.cclet.2022.07.042

  5. [5]

     T.C. Pham, V.N. Nguyen, Y. Choi, S. Lee, J. Yoon, Chem. Rev. 121 (2021) 13454-13619. doi: 10.1021/acs.chemrev.1c00381

  6. [6]

     X. Zhao, J. Liu, J. Fan, H. Chao, X. Peng, Chem. Soc. Rev. 50 (2021) 4185-4219. doi: 10.1039/d0cs00173b

  7. [7]

     A. Sharma, P. Verwilst, M. Li, et al., Chem. Rev. 124 (2024) 2699-2804. doi: 10.1021/acs.chemrev.3c00778

  8. [8]

     J. Qi, H. Ou, Q. Liu, D. Ding, Aggregate 2 (2021) 95-113. doi: 10.1002/agt2.25

  9. [9]

     J.P. Celli, B.Q. Spring, I. Rizvi, et al., Chem. Rev. 110 (2010) 2795-2838. doi: 10.1021/cr900300p

  10. [10]

      D.E.J.G.J. Dolmans, D. Fukumura, R.K. Jain, Nat. Rev. Cancer 3 (2003) 380-387. doi: 10.1038/nrc1071

  11. [11]

      S. Zhang, W. Yang, X. Lu, et al., Chem. Sci. 14 (2023) 7076-7085. doi: 10.1039/d3sc00588g

  12. [12]

      Y.Y. Zhao, L. Zhang, Z. Chen, et al., J. Am. Chem. Soc. 143 (2021) 13980-13989. doi: 10.1021/jacs.1c07479

  13. [13]

      Y. Tang, Y. Li, B. Li, et al., Nat. Commun. 15 (2024) 2530. doi: 10.1038/s41467-024-46768-w

  14. [14]

      Q. Zhao, G. Qing, J. Yu, et al., Chin. Chem. Lett. 35 (2024) 108535. doi: 10.1016/j.cclet.2023.108535

  15. [15]

      V.N. Nguyen, S. Qi, S. Kim, et al., J. Am. Chem. Soc. 141 (2019) 16243-16248. doi: 10.1021/jacs.9b09220

  16. [16]

      Y. Yu, S. Wu, L. Zhang, et al., Biomaterials 280 (2022) 121255. doi: 10.1016/j.biomaterials.2021.121255

  17. [17]

      J. Zhang, W. Ma, H. Luo, et al., Adv. Healthcare Mater. 13 (2024) e2303175. doi: 10.1002/adhm.202303175

  18. [18]

      B. Lu, Y. Huang, Z. Zhang, H. Quan, Y. Yao, Mater. Chem. Front. 6 (2022) 2968-2993. doi: 10.1039/d2qm00752e

  19. [19]

      Y.Y. Zhao, H. Kim, V.N. Nguyen, et al., Coord. Chem. Rev. 501 (2024) 215560. doi: 10.1016/j.ccr.2023.215560

  20. [20]

      W.F. Watson, R. Livingston, Nature 162 (1948) 452-453. doi: 10.1038/162452a0

  21. [21]

      Z. Zhao, H. Zhang, J.W.Y. Lam, B.Z. Tang, Angew. Chem. Int. Ed. 59 (2020) 9888-9907. doi: 10.1002/anie.201916729

  22. [22]

      Z. Li, B.Z. Tang, D. Wang, Adv. Mater. 36 (2024) 2406047. doi: 10.1002/adma.202406047

  23. [23]

      M.Y. Wu, M. Gu, J.K. Leung, et al., Small 17 (2021) e2101770. doi: 10.1002/smll.202101770

  24. [24]

      J. Wang, Y. Wang, Z. Li, et al., Chin. Chem. Lett. 35 (2024) 108934. doi: 10.1016/j.cclet.2023.108934

  25. [25]

      Z. Liu, Q. Wang, W. Qiu, et al., Chem. Sci. 13 (2022) 3599-3608. doi: 10.1039/d2sc00067a

  26. [26]

      P. Cen, J. Huang, C. Jin, et al., Aggregate 4 (2023) e352. doi: 10.1002/agt2.352

  27. [27]

      H. Zhang, C. He, L. Shen, et al., Chin. Chem. Lett. 34 (2023) 108160. doi: 10.1016/j.cclet.2023.108160

  28. [28]

      G. Feng, B. Liu, Small 12 (2016) 6528-6535. doi: 10.1002/smll.201601637

  29. [29]

      X. Yang, X. Wang, X. Zhang, et al., Adv. Mater. 36 (2024) 2402182. doi: 10.1002/adma.202402182

  30. [30]

      H. Xie, Z. Bi, J. Yin, et al., ACS Nano 17 (2023) 4591-4600. doi: 10.1021/acsnano.2c10661

  31. [31]

      A.M. Smith, M.C. Mancini, S. Nie, Nat. Nanotechnol. 4 (2009) 710-711. doi: 10.1038/nnano.2009.326

  32. [32]

      X. Cai, B. Liu, Angew. Chem. Int. Ed. 59 (2020) 9868-9886. doi: 10.1002/anie.202000845

  33. [33]

      X. Chen, L. Shi, X.Y. Ran, et al., Adv. Funct. Mater. 34 (2024) 2400728. doi: 10.1002/adfm.202400728

  34. [34]

      P. Zhang, H. Kuang, Y. Xu, et al., ACS Appl. Mater. Interfaces 12 (2020) 42551-42557. doi: 10.1021/acsami.0c12670

  35. [35]

      Y. Gui, Y. Wang, D. Wang, et al., Angew. Chem. Int. Ed. 63 (2024) e202318609. doi: 10.1002/anie.202318609

  36. [36]

      S. Yang, J. Zhang, Z. Zhang, et al., J. Am. Chem. Soc. 145 (2023) 22776-22787. doi: 10.1021/jacs.3c08627

  37. [37]

      P. Wang, S. Guo, H.J. Wang, et al., Nat. Commun. 10 (2019) 3155. doi: 10.1038/s41467-019-11099-8

  38. [38]

      S. Guo, K.K. Chen, R. Dong, et al., ACS Catal. 8 (2018) 8659-8670. doi: 10.1021/acscatal.8b02226

  39. [39]

      H.Y. Wang, X.Y. Zheng, L.S. Long, L.S. Zheng, X.J. Kong, Tungsten 5 (2023) 254-260. doi: 10.1007/s42864-022-00193-y

  40. [40]

      M. Cao, T. Zhu, M. Zhao, F. Meng, Z. Liu, J. Wang, G. Niu, X. Yu, Anal. Chem. 94 (2022) 10676-10684. doi: 10.1021/acs.analchem.2c00964

  41. [41]

      L.H. Xiong, L. Yang, J. Geng, B.Z. Tang, X. He, ACS Nano 18 (2024) 17837-17851. doi: 10.1021/acsnano.4c03879

  42. [42]

      S. Song, Y. Zhao, M. Kang, et al., Adv. Mater. 36 (2024) e2309748. doi: 10.1002/adma.202309748

  43. [43]

      J. Wang, H. Li, Y. Zhu, et al., Chem. Sci. 14 (2023) 323-330. doi: 10.1039/d2sc06445f

  44. [44]

      W. Chen, Z. Wang, G. Hong, et al., Chem. Sci. 15 (2024) 10945-10953. doi: 10.1039/d4sc03008g

  45. [45]

      Y. Li, D. Zhang, Y. Yu, et al., ACS Nano 17 (2023) 16993-17003. doi: 10.1021/acsnano.3c04256

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  Scheme 1  Schematic illustration of π bridge engineering of TPCPY and TFCPY, and FLI-guided PDT.

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  Figure 1  (A) The absorption spectra of TPCPY and TFCPY in DMSO solutions (10 µmol/L). (B) Photoluminescence (PL) spectra of TFCPY (5 × 10⁻⁵ mol/L) in DMSO/toluene mixtures with different toluene fractions (λ_ex: 510 nm). (C) Plots of relative PL intensity (I/I₀) versus the composition of different solution mixtures of designed PSs. (D) The particle size distribution of both PSs detected from DLS (Insert: TEM images, scale bar: 200 nm). (E) Zeta potential of TPCPY and TFCPY. (F) Optimized molecular structures, (G) HOMO-LUMO distribution, and (H) energy level diagrams and SOC values of excited singlet and triplet states for TPCPY and TFCPY (isocontour value = 0.2).

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  Figure 2  ROS generation capability of TPCPY or TFCPY evaluated by different indicators under irradiation (white light, 42 mW/cm²). (A) The relative fluorescence intensity (Ⅰ/Ⅰ₀) of DCFH solution at 524 nm containing PSs versus the irradiation time (DCFH: 40 µmol/L, photosensitizers: 2 µmol/L). (B) The decomposition rates of ABDA at 378 nm absorbance in the presence of PSs (ABDA: 100 µmol/L, photosensitizers: 20 µmol/L). (C) Time-course plots activation rates of DHR123 solution containing PSs with different irradiation time (DHR123: 5 µmol/L, photosensitizers: 2 µmol/L). (D) The relative fluorescence intensity (Ⅰ/Ⅰ₀) of HPF solution containing PSs versus the irradiation time (HPF: 5 µmol/L, PSs: 2 µmol/L).

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  Figure 3  (A) Intracellular ROS detection by DCFH-DA in HeLa cells treated with TPCPY and TFCPY under white light irradiation. Scale bar: 50 µm (top) and 100 µm (bottom). (B) Dose-dependent cytotoxicity of TPCPY to HeLa cells. (C) Dose-dependent cytotoxicity of TFCPY to HeLa cells. Data are presented as mean ± standard deviation (SD) (n = 3). (D) Live/dead cells imaging of HeLa cells stained with FDA/PI after incubation with TFCPY under white light irradiation. Scale bar: 50 µm. (E) Live/dead cells imaging of HeLa cells stained with FDA/PI (FDA: 1 mg/mL, PI: 100 mg/mL) after incubation with TFCPY under white light irradiation for 20 min (42 mW/cm²). Scale bar: 50 µm.

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  Figure 4  In vivo antitumor capacity of TFCPY in 4T1 tumor-bearing mice model. (A) Schematic diagram of establishing tumor models and in vivo therapeutic process. (B) The fluorescence imaging after intratumor injection of TFCPY with 48 h. (C) The tumor growth curves of different treatment groups. (D) Photograph of tumor sections collected from different treatment groups. (E) The tumor tissue weights from the sacrificed mice. Data are presented as mean ± SD (n = 4). ***P < 0.001. (F) H & E and TUNEL staining of tumor tissues with different treatments (light treatment conditions (+L): irradiation by white light, 100 mW/cm²).

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