A carbazole functionalized semiconducting compound as a heavy atom free photosensitizer for phototherapy against lung cancer

Advances and challenges in the treatment of lung cancer

Lung cancer accounts for a relatively high proportion of malignant tumors. As the most prevalent type of lung cancer, non-small cell lung cancer (NSCLC) is characterized by high morbidity and mortality. Presently, the arsenal of treatment strategies encompasses surgical resection, chemotherapy, targeted therapy and radiotherapy. However, despite these options, the prognosis remains distressingly poor with a low 5-year survival rate. Therefore, it is urgent to pursue a paradigm shift in treatment methodologies. In recent years, the advent of sophisticated biotechnologies and interdisciplinary integration has provided innovative approaches for the treatment of lung cancer. This article reviews the cutting-edge developments in the nano drug delivery system, molecular targeted treatment system, photothermal treatment strategy, and immunotherapy for lung cancer. Overall, by systematically summarizing and critically analyzing the latest progress and current challenges in these treatment strategies of lung cancer, we aim to provide a theoretical basis for the development of novel drugs for lung cancer treatment, and thus improve the therapeutic outcomes for lung cancer patients.

Enhancing electron transfer of a semiconducting polymer for type I photodynamic and photothermal synergistic therapy

Tumor hypoxia is responsible for the reduced therapeutic efficacy of type II photodynamic therapy (PDT) because of the dependence of cellular oxygen during ¹O₂ generation. Type I PDT may be a better strategy to overcome the disadvantages of hypoxia for enhanced theranostics. Herein, a new semiconducting polymer PDPP was synthesized and encapsulated with hydrophilic PEG-PDPA to enhance the electron transfer for type I PDT. PDPP NPs show a high superoxide radical generation ability with DHR123 as a probe. In vitro MTT assay indicates PDPP NPs with considerably high phototoxicity on human cervical cancer cells (HeLa) with a low half-maximal inhibitory concentration (IC₅₀) of 6.1 μg/ml. Furthermore, an in vivo study demonstrates that PDPP NPs can lead to complete tumor suppression with the help of laser, compared with the control and dark groups. The biosafety is confirmed by the H&E analysis of the normal tissues (the heart, liver, spleen, lungs, and kidney). The results provide a strategy to design nanosystems for type I PDT and PTT synergistic therapy.

A novel heptamethine cyanine photosensitizer for FRET-amplified photodynamic therapy and two-photon imaging in A-549 cells

In this study, a new cyanine-based photosensitizer Cy-N-Rh was developed for photodynamic therapy. Based on fluorescence resonance energy transfer (FRET) mechanism, utilizing the absorption of the donor rhodamine (Rh), the acceptor heptamethine cyanine unit (Cy) was indirectly excited to produce singlet oxygen (¹O₂). The efficiency of energy transfer from the donor Rh to the acceptor Cy was 78.5%. Meanwhile, the singlet oxygen yield of Cy-N-Rh (Φ_Δ = 12.00%) was much higher than that of the acceptor Cy (Φ_Δ = 4.35%) without FRET. Moreover, the dual cation gave Cy-N-Rh with excellent mitochondria-targeting ability with Pearson's correlation coefficients of 0.90 and 0.91, respectively. In the MTT test, Cy-N-Rh had low dark cytotoxicity with cell survival rate above 90% and high photo cytotoxicity with cell survival rate below 40%. The cell apoptosis assay also demonstrated the role of the photosensitizer Cy-N-R visually. More importantly, Cy-N-Rh fulfilled two-photon excitation fluorescence imaging under the 800 nm femtosecond laser. All results indicate that this design strategy provides a new method for the development of higher-level cyanine photosensitizers.

Delivering Singlet Oxygen in Dark Condition With an Anthracene-Functionalized Semiconducting Compound for Enhanced Phototheranostics

Photodynamic therapy (PDT) utilizes the photogeneration of reactive oxygen species (ROS) with high cytotoxicity to kill cancer cells, holding great promise for cancer treatment. Fractionated delivery of singlet oxygen (¹O₂) is a wise approach to relieving hypoxia, thus enhancing the therapeutic efficacy. In this article, an anthracene-functionalized semiconducting compound (DPPA) has been designed and synthesized. With irradiation, the compound is able to undergo efficient intersystem crossing (ISC) and non-radioactive decay for photodynamic/photothermal synergistic therapy. In addition, the anthracene module is able to capture and release ¹O₂ reversibly with or without irradiation. DPPA nanoparticles (NPs) obtained by nanoprecipitation with DSPE-PEG exhibit considerable high phototoxicity on human kidney cancer cells (A498), and the half maximum inhibitory concentration (IC₅₀) is 15.8 μg/ml. Furthermore, an in vivo study demonstrates that complete tumor suppression was observed when the mice were administered DPPA NPs with the help of laser, compared with the control and dark groups. The H&E analysis of the normal tissues (the heart, liver, spleen, lungs, and kidney) indicates that such NPs cause no side effects, indicating the biosafety of DPPA NPs. The results provide a strategy to design a heavy-atom–free photosensitizer for photothermal and fractionated PDT against kidney tumors.

An unprecedented spike of the electroluminescence turn-on transience from guest-doped OLEDs with strong electron-donating abilities of host carbazole groups

An unreported unprecedented spike of ∼μs line-width, followed by an overshoot, was discovered at the rising edge of transient electroluminescence (TEL) from guest-doped organic light-emitting diodes with strong electron-donating abilities from the host carbazole groups. By changing the device structures and TEL measurement parameters, a series of experimental results demonstrate that this TEL spike is not related to exciton interactions such as singlet-triplet and triplet-triplet annihilations but originated from the radiative recombination of pre-stored electrons with injected holes. Surprisingly, these pre-stored guest electrons do not come from the energy-level traps in the host-guest systems; instead, the guest molecules receive the electrons transferred from the host carbazole groups due to their strong electron-donating abilities. Moreover, the observed spikes show rich and extraordinary temperature dependences. Based on the detailed understanding of the spike formation mechanism, we have proposed the requirements for the occurrence of spike and realized the artificial adjustments of the spike intensity. For instance, the instantaneous luminescent intensity of this spike can reach over 80 times the magnitude of the TEL plateau. Accordingly, this work deepens the physical understanding of this novel spike in TEL and paves the way for fabricating an electro-optic sensor to detect instantaneous weak current signals.