Molecular engineering of a spheroid-penetrating phage nanovector for photodynamic treatment of colon cancer cells.

Photodynamic therapy (PDT) represents an emerging strategy to treat various malignancies, including colorectal cancer (CC), the third most common cancer type. This work presents an engineered M13 phage retargeted towards CC cells through pentavalent display of a disulfide-constrained peptide nonamer. The M13CC nanovector was conjugated with the photosensitizer Rose Bengal (RB), and the photodynamic anticancer effects of the resulting M13CC-RB bioconjugate were investigated on CC cells. We show that upon irradiation M13CC-RB is able to impair CC cell viability, and that this effect depends on i) photosensitizer concentration and ii) targeting efficiency towards CC cell lines, proving the specificity of the vector compared to unmodified M13 phage. We also demonstrate that M13CC-RB enhances generation and intracellular accumulation of reactive oxygen species (ROS) triggering CC cell death. To further investigate the anticancer potential of M13CC-RB, we performed PDT experiments on 3D CC spheroids, proving, for the first time, the ability of engineered M13 phage conjugates to deeply penetrate multicellular spheroids. Moreover, significant photodynamic effects, including spheroid disruption and cytotoxicity, were readily triggered at picomolar concentrations of the phage vector. Taken together, our results promote engineered M13 phages as promising nanovector platform for targeted photosensitization, paving the way to novel adjuvant approaches to fight CC malignancies.

Electron-Withdrawing Substituents Enhance the Type I PDT and NIR-II Fluorescence of BODIPY J Aggregates for Bioimaging and Cancer Therapy.

Organic dyes with simultaneously boosted near-infrared-II (NIR-II) fluorescence, type I photodynamic therapy (PDT), and photothermal therapy (PTT) in the aggregate state are still elusive due to the unclear structure-function relationship. Herein, electron-withdrawing substituents are introduced at the 5-indolyl positions of BODIPY dyes to form tight J-aggregates for enhanced NIR-II fluorescence and type I PDT/PTT. The introduction of an electron-rich julolidine group at the meso position and an electron-withdrawing substituent (-F) at the indolyl moiety can enhance intermolecular charge transfer and the hydrogen bonding effect, contributing to the efficient generation of superoxide radicals in the aggregate state. The nanoparticles of BDP-F exhibit NIR-II fluorescence at 1000 nm, good superoxide radical generation ability, and a high photothermal conversion efficiency (50.9%), which enabled NIR-II fluorescence-guided vasculature/tumor imaging and additive PDT/PTT. This work provides a strategy for constructing phototheranostic agents with enhanced NIR-II fluorescence and type I PDT/PTT for broad biomedical applications.

The Latest Look at PDT and Immune Checkpoints.

Photodynamic therapy (PDT) can not only directly eliminate cancer cells, but can also stimulate antitumor immune responses. It also affects the expression of immune checkpoints. The purpose of this review is to collect, analyze, and summarize recent news about PDT and immune checkpoints, along with their inhibitors, and to identify future research directions that may enhance the effectiveness of this approach. A search for research articles published between January 2023 and March 2024 was conducted in PubMed/MEDLINE. Eligibility criteria were as follows: (1) papers describing PDT and immune checkpoints, (2) only original research papers, (3) only papers describing new reports in the field of PDT and immune checkpoints, and (4) both in vitro and in vivo papers. Exclusion criteria included (1) papers written in a language other than Polish or English, (2) review papers, and (3) papers published before January 2023. 24 papers describing new data on PDT and immune checkpoints have been published since January 2023. These included information on the effects of PDT on immune checkpoints, and attempts to associate PDT with ICI and with other molecules to modulate immune checkpoints, improve the immunosuppressive environment of the tumor, and resolve PDT-related problems. They also focused on the development of new nanoparticles that can improve the delivery of photosensitizers and drugs selectively to the tumor. The effect of PDT on the level of immune checkpoints and the associated activity of the immune system has not been fully elucidated further, and reports in this area are divergent, indicating the complexity of the interaction between PDT and the immune system. PDT-based strategies have been shown to have a beneficial effect on the delivery of ICI to the tumor. The utility of PDT in enhancing the induction of the antitumor response by participating in the triggering of immunogenic cell death, the exposure of tumor antigens, and the release of various alarm signals that together promote the activation of dendritic cells and other components of the immune system has also been demonstrated, with the result that PDT can enhance the antitumor immune response induced by ICI therapy. PDT also enables multifaceted regulation of the tumor's immunosuppressive environment, as a result of which ICI therapy has the potential to achieve better antitumor efficacy. The current review has presented evidence of PDT's ability to modulate the level of immune checkpoints and the effectiveness of the association of PDT with ICIs and other molecules in inducing an effective immune response against cancer cells. However, these studies are at an early stage and many more observations need to be made to confirm their efficacy. The new research directions indicated may contribute to the development of further strategies.

5-Aminolevulinic acid-mediated photodynamic therapy in combination with kinase inhibitor lapatinib enhances glioblastoma cell death.

5-Aminolevulinic acid (ALA) is an intraoperative imaging agent approved for protoporphyrin IX (PpIX) fluorescence-guided resection of glioblastoma (GBM). It is currently under clinical evaluation for photodynamic therapy (PDT) after the completion of GBM surgery. We previously showed that lapatinib, a clinical kinase inhibitor of epidermal growth factor receptor 1 & 2 (EGFR and HER2), enhanced PpIX fluorescence in a panel of GBM cell lines by blocking ABCG2 (ATP-binding cassette super-family G member 2)-mediated PpIX efflux, which suggests its potential for improving ALA for GBM surgery and PDT. Here we show that lapatinib enhanced PDT-induced cytotoxicity by promoting GBM cell death with the induction of apoptosis followed by necrosis. While the induction of tumor cell apoptosis was massive and rapid in the H4 cell line with no detectable Bcl-2 and a low level of Bcl-xL, it was delayed and much less in extent in A172, U-87 and U-118 cell lines with higher levels of pro-survival Bcl-2 family proteins. Lapatinib treatment alone neither reduced GBM cell viability nor had any significant effect on EGFR downstream signaling. Its enhancement of ALA-PDT was largely due to the increase of intracellular PpIX particularly in the mitochondria, resulting in the activation of mitochondria-mediated apoptosis in H4 cells. Our present study demonstrates that lapatinib inhibits ABCG2-mediated PpIX efflux and sensitizes GBM cells to ALA-PDT by inducing tumor cell death.

Ruthenium complexes bearing nile red chromophore and one of its derivative: Theoretical evaluation of PDT-related properties.

The outcomes of DFT-based calculations are here reported to assess the applicability of two synthesized polypyridyl Ru(II) complexes, bearing ethynyl nile red (NR) on a bpy ligand, and two analogues, bearing modified-NR, in photodynamic therapy. The absorption spectra, together with the non-radiative rate constants for the S1 - Tn intersystem crossing transitions, have been computed for this purpose. Calculations evidence that the structural modification on the chromophore destabilizes the HOMO of the complexes thus reducing the H-L gap and, consequently, red shifting the maximum absorption wavelength within the therapeutic window, up to 620 nm. Moreover, the favored ISC process from the bright state involves the triplet state closest in energy, which is also characterized by the highest SOC value and by the involvement of the whole bpy ligand bearing the chromophore in delocalising the unpaired electrons. These outcomes show that the photophysical behavior of the complexes is dominated by the chromophore.

Local Regulation of Mitochondrial Respiratory for Enhancing Photodynamic Therapy and Breaking Chemoresistance in Hypoxia.

The hypoxic condition in solid tumors induces therapy resistance, limited therapeutic efficacy, and tumor recurrence, especially for chemotherapy and aerobic photodynamic therapy (PDT). To address this matter, an O2 regulator (SNP@Ato) is designed for breaking chemoresistance and enhancing PDT, which is constructed by loading Atovaquone (Ato) through self-assembly and host-guest interaction between ß-cyclodextrin functionalized tetraphenylporphyrin (TPP-CD4) and thioketal-linked camptothecin/azobenzene (Azo-TK-CPT). Specifically, the porphyrin units in SNP@Ato are in "Off state" due to the photoinduced electron transfer (PET) effect between the porphyrin units and azobenzene. After encountering the hypoxic condition in solid tumors, SNP@Ato is dissociated by the cleaved azobenzene on account of over-expressed azo-reductase. Then the mitochondrial respiratory of cancer cells would be suppressed with the participation of Ato, generating a local hypoxia relief for sensitized chemotherapy and enhanced PDT. Accompanied by efficient PDT, the TK linker is broken by ROS, and the CPT is released from the prodrugs. Compared with the SNP group without oxygen-regulator, SNP@Ato exhibits a remarkable improvement of the therapeutic effect against hypoxic tumors in vitro and in vivo. This work proposes a novel paradigm for overcoming hypoxia-induced therapeutic resistance.

RSS and ROS Sequentially Activated Carbon Monoxide Release for Boosting NIR Imaging-Guided On-Demand Photodynamic Therapy.

Carbon monoxide shows great therapeutic potential in anti-cancer. In particular, the construction of multifunctional CO delivery systems can promote the precise delivery of CO and achieve ideal therapeutic effects, but there are still great challenges in design. In this work, a RSS and ROS sequentially activated CO delivery system is developed for boosting NIR imaging-guided on-demand photodynamic therapy. This designed system is composed of a CO releaser (BOD-CO) and a photosensitizer (BOD-I). BOD-CO can be specifically activated by hydrogen sulfide with simultaneous release of CO donor and NIR fluorescence that can identify H2S-rich tumors and guide light therapy, also depleting H2S in the process. Moreover, BOD-I generates 1O2 under long-wavelength light irradiation, enabling both PDT and precise local release of CO via a photooxidation mechanism. Such sequential activation of CO release by RSS and ROS ensured the safety and controllability of CO delivery, and effectively avoided leakage during delivery. Importantly, cytotoxicity and in vivo studies reveal that the release of CO combined with the depletion of endogenous H2S amplified PDT, achieving ideal anticancer results. It is believed that such theranostic nanoplatform can provide a novel strategy for the precise CO delivery and combined therapy involved in gas therapy and PDT.

Mucus-Penetrating Nanoassembly as Potential Oral Phototherapeutic Formulation against Multi-Drug Resistant Helicobacter pylori Infection.

Helicobacter pylori (H. pylori) infection presents increasing challenges to antibiotic therapies in limited penetration through gastric mucus, multi-drug resistance (MDR), biofilm formation, and intestinal microflora dysbiosis. To address these problems, herein, a mucus-penetrating phototherapeutic nanomedicine (RLs@T780TG) against MDR H. pylori infection is engineered. The RLs@T780TG is assembled with a near-infrared photosensitizer T780T-Gu and an anionic component rhamnolipids (RLs) for deep mucus penetration and light-induced anti-H. pylori performances. With optimized suitable size, hydrophilicity and weak negative surface, the RLs@T780TG can effectively penetrate through the gastric mucus layer and target the inflammatory site. Subsequently, under irradiation, the structure of RLs@T780TG is disrupted and facilitates the T780T-Gu releasing to target the H. pylori surface and ablate multi-drug resistant (MDR) H. pylori. In vivo, RLs@T780TG phototherapy exhibits impressive eradication against H. pylori. The gastric lesions are significantly alleviated and intestinal bacteria balance is less affected than antibiotic treatment. Summarily, this work provides a potential nanomedicine design to facilitate in vivo phototherapy in treatment of H. pylori infection.

Self-Oxygenated Hydrogel Enhances Immune Cell Response and Infiltration Via Triggering Dual DNA Damage to Activate cGAS-STING and Inhibiting CAFs.

Immune checkpoint inhibitors (ICIs) offer promise in breaking through the treatment and survival dilemma of triple-negative breast cancer (TNBC), yet only immunomodulatory subtype and ≈5% TNBC patients respond as monotherapy due to lack of effector immune cells (internal problem) and physical barrier (external limitation) formed by cancer-associated fibroblasts (CAFs). A hydrogel drug-delivery platform, ALG@TBP-2/Pt(0)/nintedanib (ALG@TPN), is designed to induce strong immune functions and the dual elimination of the internal and external tumor microenvironment (TME). Activated by white light, through type I and II photodynamic therapy (PDT), TBP-2 generates large amounts of reactive oxygen species (ROS) intracellularly, oxidizing mitochondrial DNA (mtDNA). The unique catalase activity of Pt(0) converts endogenous H2O2 to O2, reducing the anoxia-limiting PDT and enhancing ROS generation efficacy. Abundant ROS can oxidize Pt(0) to cytotoxic Pt(II), damaging the nuclear DNA (nDNA). Dual damage to mtDNA and nDNA might bi-directionally activate the cGAS/STING pathway and enhance the immune cell response. Besides, nintedanib demonstrates a significant inhibitory effect on CAFs, weakening the immune barrier and deepening immune cell infiltration. Overall, the study provides a self-oxygenating hydrogel with the "PDT/chemotherapy/anti-CAFs" effect, triggering the cGAS/STING pathway to reshape the TME. Both internal and external interventions increase anti-TNBC immune responses.

An Integrated Nanoplatform via Dual Channel Excitation for Both Precise Fluorescence Imaging and Photodynamic Therapy of Orthotopic Breast Tumor in NIR-II Region.

Although research on photodynamic therapy (PDT) of malignant tumor has made considerable progress in recent years, it is a remaining challenge to extend PDT to the second near-infrared window (NIR-II) along with real-time and accurate NIR-II fluorescence imaging to determine drug enrichment status and achieve high treatment efficacy. In this work, lanthanide nanoparticles (Ln NPs)-based nanoplatform (LCR) equipped with photosensitizer Chlorin e6 (Ce6) and targeting molecular NH2-PEG1000-cRGDfK are developed, which can achieve NIR-II photodynamic therapy (PDT) and NIR-II fluorescence imaging by dual channel excitation. Under 808 nm excitation, Nd3+ in the outer layer can absorb the energy and transfer inward to emit strong NIR-II emissions (1064 and 1525 nm). Due to the low background noise of NIR-II light and the targeting effect of NH2-PEG1000-cRGDfK, LCR can recognize tiny tumor tissue (≈3 mm) and monitor drug distribution in vivo. Under 1530 nm excitation, internal Er3+ can be self-sensitized, generating intense upconversion emission (662 nm) that can effectively activate Ce6 for in vivo PDT due to the deep tissue penetration of NIR-II light. This study provides a paradigm of theranostic nanoplatform for both real-time fluorescence imaging and PDT of orthotopic breast tumor in NIR-II window.

Catalytic and Selective Red Light-Triggered Photodegradation of a G-Quadruplex DNA by a Zinc (II) Phthalocyanine.

Water-soluble phthalocyanine (Pc) derivatives have been regarded as potential G-quadruplex (G4) nucleic acid-targeting ligands for anticancer therapy and have been extensively studied as effective photosensitizers for photodynamic therapy (PDT). Understanding how photosensitizers interact with nucleic acids and the subsequent photolytic reactions is essential for deciphering the initial steps of PDT, thereby aiding in the development of new photosensitizing agents. In this study, we found that red-light irradiation of a mixture of a Zn(II) Pc derivative and an all-parallel G4 DNA leads to catalytic and selective photodegradation of the DNA by reactive oxygen species (ROS) generated from the Zn(II) Pc derivative bound to DNA through a reaction mechanism similar to that of an enzyme reaction. This finding provides a novel insight into the molecular design of a photosensitizer to enhance its PDT efficacy.

Phototoxicity of cyclometallated Ir(III) complexes bearing a thio-bis-benzimidazole ligand, and its monodentate analogue, as potential PDT photosensitisers in cancer cell killing.

Two novel cyclometallated iridium(III) complexes have been prepared with one bidentate or two monodentate imidazole-based ligands, 1 and 2, respectively. The complexes showed intense emission with long lifetimes of the excited state. Femtosecond transient absorption experiments established the nature of the lowest excited state as 3IL state. Singlet oxygen generation with good yields (40% for 1 and 82% for 2) was established by detecting 1O2 directly, through its emission at 1270 nm. Photostability studies were also performed to assess the viability of the complexes as photosensitizers (PS) for photodynamic therapy (PDT). Complex 1 was selected as a good candidate to investigate light-activated killing of cells, whilst complex 2 was found to be toxic in the dark and unstable under light. Complex 1 demonstrated high phototoxicity indexes (PI) in the visible region, PI > 250 after irradiation at 405 nm and PI > 150 at 455 nm, in EJ bladder cancer cells.

Synthesis and Spectroscopic Study of a Homogenous Bimetallic Os(II) Complex as a New Gastric Cancer Photosensitizer.

A homogenous dinuclear Os(II) complex bisOs was synthesized and fully characterized. The electrochemical cyclic voltammetry study, and density functional theory (DFT) and time-dependent DFT (TD-DFT) calculations were performed to investigate the electronic property. bisOs showed an obvious interaction with lipase and BSA, and can generate singlet oxygen under blue and red LED light irradiation, with a singlet oxygen quantum yield (ФΔ) of 0.36 in comparison to that of [Ru(bpy)3]Cl2 in acetonitrile. bisOs exhibited moderate to great photocytotoxicity against HGC-27 human gastric cancer cells under blue LED light irradiation, giving the IC50 value as low as 1.83 µM (PI value is 9.7), while was almost non-cytotoxic in the dark. The cellular singlet oxygen detection in HGC-27 cancer cells exhibited a concentration-dependent manner, and cell uptake of bisOs in A549 cells was as high as 120 ng/106 cells, subcellular colocalization study indicated that bisOs was not accumulated in nucleus, and less likely to target mitochondria. This work provides a new example of dinuclear osmium complex as potential photosensitizer candidate for gastric treatment.

Application of Mono and Trinuclear Cyclometalated Iridium (III) Complexes in Differential Bacterial Imaging and Antimicrobial Photodynamic Therapy.

The application of transition metal complexes for antimicrobial photodynamic therapy (PDT) has emerged as an attractive alternative in mitigating a broad range of bacterial pathogens, including multidrug-resistant pathogens. In view of their photostability, long excited-state lifetimes, and tunable emission properties, transition metal complexes also contribute as bioimaging agents. In the present work, we designed mono and trinuclear cyclometalated iridium (III) complexes to explore their imaging application and antibacterial potential. For this, we used Methicillin-resistant S. aureus (MRSA), the most prevalent of community-associated (CA) multidrug-resistant (MDR) bacteria (CA MDR) and Lactococcus lactis (L. lactis) as Gram-positive while Campylobacter jejuni (C. jejuni) and E. coli as Gram-negative bacteria. In addition to differential bioimaging of these bacteria, we assessed the antibacterial effects of both mono and trinuclear Ir(III) complexes under exposure to 427 nm LED light. The data presented herein strongly suggest better efficacy of trinuclear Ir(III) complex over the mononuclear complex in imparting photoinduced cell death of MRSA. Based on the safety profile of these complexes, we propose that trinuclear cyclometalated iridium(III) complex holds great promise for selective recognition and targeting MDR bacteria with minimal off-target effect.

Thio and Seleno Derivatives of Angelicin as Efficient Triplet Harvesting Photosensitizers: Implications in Photodynamic Therapy.

Photodynamic therapy (PDT) is widely accepted in medical practice for its targeted induction of apoptosis in cancerous cells. Angelicin (Ang) has traditionally been known for its efficacy in cancer treatment and its capability to enter a photoexcited triplet state. This study has comprehensively assessed the effects of substituting individual chalcogen atoms at three specific positions in Angelicin, with the objective of facilitating access to this elusive triplet state to enhance its role as a photosensitizer in PDT. The study scrutinizes various enhancements and factors that are crucial for efficient triplet harvesting. The decrease in singlet-triplet energy gap (ΔEST) and increased spin-orbit coupling (SOC) values present numerous viable pathways for intersystem crossing (ISC), leading to the triplet manifold. The lifetime of ISC, thus, decreases from 10-5 s-1 in Ang to 10­8 s-1 in thioangelicin (TAng) and finally to 10-9 s-1 in selenoangelicin (SeAng). Additionally, this study investigates the two-photon absorption properties of thio and seleno-substituted Angelicin for their potentialities as non-UV photosensitizers. The interplay between electron-withdrawing and electron-donating substitutions in these derivatives significantly enhances the two-photon absorption cross-sections (σ) to as high as 49.3 GM while shifting the absorption wavelengths towards the infrared region enabling them as efficient PDT photosensitizers.

Recent development of nanomaterials-based PDT to improve immunogenic cell death.

Photodynamic therapy (PDT) is a clinically approved therapeutic modality for treating oncological and non-oncological disorders. PDT has proclaimed multiple benefits over further traditional cancer therapies including its minimal systemic toxicity and selective ability to eliminate irradiated tumors. In PDT, a photosensitizing substance localizes in tumor tissues and becomes active when exposed to a particular wavelength of laser light. This produces reactive oxygen species (ROS), which induce neoplastic cells to die and lead to the regression of tumors. The contributions of ROS to PDT-induced tumor destruction are described by three basic processes including direct or indirect cell death, vascular destruction, and immunogenic cell death. However, the efficiency of PDT is significantly limited by the inherent nature and tumor microenvironment. Combining immunotherapy with PDT has recently been shown to improve tumor immunogenicity while decreasing immunoregulatory repression, thereby gently modifying the anticancer immune response with long-term immunological memory effects. This review highlights the fundamental ideas, essential elements, and mechanisms of PDT as well as nanomaterial-based PDT to boost tumor immunogenicity. Moreover, the synergistic use of immunotherapy in combination with PDT to enhance immune responses against tumors is emphasized.

Hypericin-mediated photodynamic therapy inhibits metastasis and EMT of colorectal cancer cells by regulating RhoA-ROCK1 signaling pathway.

Colorectal cancer (CRC) is significantly contributed to global cancer mortality rates. Treating CRC is particularly challenging due to metastasis and drug resistance. There is a pressing need for new treatment strategies against metastatic CRC. Photodynamic therapy (PDT) offers a well-established, minimally invasive treatment option for cancer with limited side effects. Hypericin (HYP), a potent photosensitizer for PDT, has been documented to induce cytotoxicity and apoptosis in various types of cancers. However, there are few reports on the inhibitory effects of HYP-mediated PDT on the metastatic ability of CRC cells. Here, we evaluate the inhibitory effects of HYP-mediated PDT against metastatic CRC cells and define its underlying mechanisms. Wound-healing and Transwell assays show that HYP-mediated PDT suppresses migration and invasion of CRC cells. F-actin visualization assays indicate HYP-mediated PDT decreases F-actin formation in CRC cells. TEM assays reveal HYP-mediated PDT disrupts pseudopodia formation of CRC cells. Mechanistically, immunofluorescence and western blotting results show that HYP-mediated PDT upregulates E-cadherin and downregulates N-cadherin and Vimentin. HYP-mediated PDT also suppresses key EMT regulators, including Snail, MMP9, ZEB1 and α-SMA. Additionally, the expressions of RhoA and ROCK1 are downregulated by HYP-mediated PDT. Together, these findings suggest that HYP-mediated PDT inhibits the migration and invasion of HCT116 and SW620 cells by modulating EMT and RhoA-ROCK1 signaling pathway. Thus, HYP-mediated PDT presents a potential therapeutic option for CRC.

Compounding Methylene Blue with Selenium-decorated Graphene Quantum Dots to Improve Singlet Oxygen Production for Photodynamic Therapy Application.

Graphene quantum dots (GQDs) are known as suitable material to be applied in different fields such as photodynamic therapy (PDT). Herein, GQDs were synthesized by the pyrolysis method and then decorated with selenium (Se). Afterward, they were combined with methylene blue (MB) to increase singlet oxygen generation as well as to apply them more effectively in the PDT method. Furthermore, GQDs were investigated by transmission electron microscope (TEM), photoluminescence spectrum (PL), Fourier-transform infrared spectroscopy (FTIR), field emission scanning electron microscope (FESEM), reactive oxygen species (ROS) measurement, and cytotoxicity measurement. GQDs showed no dependence on the excitation wavelength. The result of ROS measurement proves that the combination of GQD-Se and MB increases singlet oxygen production. Moreover, afterglow measurement approved the beneficial effect of GQD-Se on even deep and near skin tumor treatment. Cytotoxicity measurements under dark conditions, cell viability, and the side effects on human cells were determined by (3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide) (MTT) assay. Our findings show that under dark conditions, even high concentrations of nanoparticles have no significant effect on cell viability. These findings and the high biocompatibility of GQDs indicate the effective application of GQD-Se-MB in PDT.

Gallium octacarboxyphthalocyanine hydroxide as a potential pro-apoptotic drug against cancer skin cells.

Novel anticancer strategies reduce side effects on healthy tissues by elevating the lethal abilities of cancer cells. The development of effective particles with good bioavailability and selectivity remains problematic. For undesirable features, green chemistry is used to synthesize the best compounds, or natural-based particles are improved. Photodynamic therapy (PDT), modelled on phthalocyanines (Pcs), still delivers second-generation sensitizers which are complemented with metal ions, such as Zn2+, Al3+, or Ga3+. Gallium octacarboxyphthalocyanine hydroxide (Ga(OH)PcOC), was designed for skin cancer treatment, and was used as a pro-apoptotic and pro-oxidative agent on normal skin cell lines, fibroblasts (NHDF), and keratinocytes (HaCaT), with promising selectivity against melanoma cancer cells (Me45) in vitro. Compared to the previous reported findings, where the ZnPcOC acted on the skin cell lines at higher doses, the sensitivities to the Ga(OH)PcOC allows for an effective reduction of the sensitizer dose. The effective dose, for a novel Ga(OH)PcOC particle, was significantly reduced from 30 µM to 6 µM on Me45 cancer cells, tested using 24 h MTT viability, as well as cytometric pro-oxidative and pro-apoptotic assays. The promising photosensitizer did not reduce viability in normal fibroblasts and keratinocytes without reactive oxygen species (ROS) elevation or apoptosis induction. The improvement to the previous findings is better Ga-based photosensitizer selectivity against the cancer Me45 cells, then observed in Zn-based compounds.

Facile synthesis of Gd/Ru-doped fluorescent carbon dots for fluorescent/MR bimodal imaging and tumor therapy.

Functional metal doping endows fluorescent carbon dots with richer physical and chemical properties, greatly expanding their potential in the biomedical field. Nonetheless, fabricating carbon dots with integrated functionality for diagnostic and therapeutic modalities remains challenging. Herein, we develop a simple strategy to prepare Gd/Ru bimetallic doped fluorescent carbon dots (Gd/Ru-CDs) via a one-step microwave-assisted method with Ru(dcbpy)3Cl2, citric acid, polyethyleneimine, and GdCl3 as precursors. Multiple techniques were employed to characterize the morphology and properties of the obtained carbon dots. The Gd/Ru-CDs are high mono-dispersity, uniform spherical nanoparticles with an average diameter of 4.2 nm. Moreover, X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared (FTIR) confirmed the composition and surface properties of the carbon dots. In particular, the successful doping of Gd/Ru enables the carbon dots not only show considerable magnetic resonance imaging (MRI) performance but also obtain better fluorescence (FL) properties, especially in the red emission area. More impressively, it has low cytotoxicity, excellent biocompatibility, and efficient reactive oxygen species (ROS) generation ability, making it an effective imaging-guided tumor treatment reagent. In vivo experiments have revealed that Gd/Ru-CDs can achieve light-induced tumor suppression and non-invasive fluorescence/magnetic resonance bimodal imaging reagents to monitor the treatment process of mouse tumor models. Thus, this simple and efficient carbon dot manufacturing strategy by doping functional metals has expanded avenues for the development and application of multifunctional all-in-one theranostics.