Photomedicine based on heme-derived compounds.

Photoimaging and phototherapy have become major platforms for the diagnosis and treatment of various health complications. These applications require a photosensitizer (PS) that is capable of absorbing light from a source and converting it into other energy forms for detection and therapy. While synthetic inorganic materials such as quantum dots and gold nanorods have been widely explored for their medical diagnosis and photodynamic (PDT) and photothermal (PTT) therapy capabilities, translation of these technologies has lagged, primarily owing to potential cytotoxicity and immunogenicity issues. Of the various photoreactive molecules, the naturally occurring endogenous compound heme, a constituent of red blood cells, and its derivatives, porphyrin, biliverdin and bilirubin, have shown immense potential as noteworthy candidates for clinically translatable photoreactive agents, as evidenced by previous reports. While porphyrin-based photomedicines have attracted significant attention and are well documented, research on photomedicines based on two other heme-derived compounds, biliverdin and bilirubin, has been relatively lacking. In this review, we summarize the unique photoproperties of heme-derived compounds and outline recent efforts to use them in biomedical imaging and phototherapy applications.

meso-Tetra-(4-pyridyl)porphyrin/palladium(II) complexes as anticancer agents.

This study reports the synthesis, structural characterization and cytotoxic activity of four new palladium/pyridylporphyrin complexes, with the general formula {TPyP[PdCl(P-P)]4}(PF6)4, where P-P is 1,2-bis(diphenylphosphino)ethane (dppe), 1,3-bis(diphenylphosphino)propane (dppp), 1,2-bis(diphenylphosphino)butane (dppb) or 1,1'-bis(diphenylphosphino)ferrocene (dppf). The complexes were characterized by elemental analysis, and by FT-IR, UV/Vis, 1H and 31P{1H} NMR (1D/2D) spectroscopy. The slow evaporation of a methanolic solution of {TPyP[PdCl(dppb)]4}(PF6)4 (in an excess of NaBF4 salt) resulted in single crystals suitable for X ray diffraction, allowing the determination of the tridimensional structure of this complex, which crystallized in the P21/a space group. The cytotoxicity of the complexes against MDA-MB-231 (breast cancer cells) and MCF-10A (non-tumor breast cancer cells), was determined by the colorimetric MTT method, which revealed that all four complexes show selective indexes close to 1.2, lower than that of cisplatin for the same cells (12.12). The interaction of the complexes with CT-DNA was evaluated by UV-visible and viscosity measurements and it was determined that the complexes interact moderately with CT-DNA, probably by H-bonding/π-π stacking and electrostatic interactions.

Cationic Polyporphyrins as siRNA Delivery Vectors for Photodynamic and Gene Synergistic Anticancer Therapy.

Successful gene therapy is highly dependent on the efficiency of gene delivery, which is mostly achieved by the carrier. Current gene carriers are generally nontherapeutic and take over most of the proportion in the delivery systems. Therefore, a library of polymerized and cationic photosensitive drugs (polyphotosensitizers, pPSs) with HIF-1α siRNA delivery capability is constructed to realize using "drug" to deliver "gene". The pPS component acts as both a therapeutic carrier for intracellular HIF-1α siRNA delivery and a photosensitive drug with photodynamic therapy (PDT). A reactive oxygen species (ROS)-cleavable linker is used to polymerize PS, allowing the successful segregation of PS monomers in space, avoiding the undesired aggregation-caused quenching (ACQ) effect and enhancing the in vitro and in vivo PDT effect. The complexes formed by pPSs and HIF-1α siRNA exhibited desired siRNA condensation and serum stability at the optimal conditions (pPSs with guanidines/siRNA weight ratio of 15), efficient intracellular internalization, and gene-silencing efficiency (60%) compared with commercial available transfection reagents (40%), as well as synergistic in vitro and in vivo phototoxicity for the combination PDT-gene therapy toward cancer treatment. This study provides a promising paradigm for the design of both the gene delivery carrier and the photosensitizer, as well as for broad utilities in the combination therapy toward cancer treatment.

Light-assisted anticancer photodynamic therapy using porphyrin-doped nanoencapsulates.

Light activatable porphyrinic photosensitizers (PSs) are essential components of anticancer and antimicrobial therapy and diagnostic imaging. However, their biological applications are quite challenging due to the lack of hydrophilicity and biocompatibility. To overcome such drawbacks, photosensitizers can be doped into a biocompatible polymer such as gelatin and further can be used for biomedical applications. Herein, first, a novel A4 type porphyrin PS [5,10,15,20-tetrakis(4-pyridylamidephenyl)porphyrin; TPyAPP] was synthesized via a rational route with good yield. Further, this porphyrin was encapsulated into the gelatin nanoparticles (GNPs) to develop hydrophilic phototherapeutic nanoagents (PTNAs, A4por-GNPs). Notably, the synthesis of such porphyrin-doped GNPs avoids the use of any toxic chemicals or solvents. The nanoprobes have also shown good fluorescence quantum yield demonstrating their applicability in bioimaging. Further, the mechanistic aspects of the anticancer and antimicrobial efficacy of the developed A4por-GNPs were evaluated via singlet oxygen generation studies. Overall, our results indicated porphyrin-doped biodegradable polymeric nanoparticles act as effective phototherapeutic agents against a broad range of cancer cell lines and microbes upon activation by the low-cost LED light.

H2O2 enhances the anticancer activity of TMPyP4 by ROS-mediated mitochondrial dysfunction and DNA damage.

Cancer is one of the diseases that threatens human health and is a leading cause of mortality worldwide. High levels of reactive oxygen species (ROS) have been observed in cancer tissues compared with normal tissues in vivo, and it is not yet known how this influences chemotherapeutic drug action. Cationic porphyrin 5,10,15,20-tetra-(N-methyl-4-pyridyl) porphyrin (TMPyP4) is a photosensitizer used in photodynamic therapy (PDT) and a telomerase inhibitor used in the treatment of telomerase-positive cancer. Here, we investigated the anticancer activity of TMPyP4 in A549 and PANC cells cultured in H2O2. The results showed that compared to TMPyP4 alone, the combination of TMPyP4 and H2O2 exhibited sensitization effects on cell viability and colony formation inhibition and apoptosis in A549 and PANC cells, but had no effect in human normal MIHA cells. Mechanistically, the combination of TMPyP4 and H2O2 activates high ROS and mitochondrial membrane potential in A549 and PANC cells, resulting in intense DNA damage and DNA damage responses. Consequently, compared to TMPyP4 alone, TMPyP4 and H2O2 combined treatment upregulates the expression of BAX, cleaved caspase 3, and p-JNK and downregulates the expression of Bcl-2 in A549 and PANC cells. Taken together, these data suggested that H2O2 enhanced the anticancer activity of TMPyP4-mediated ROS-dependent DNA damage and related apoptotic protein regulation, revealing that the high ROS tumor microenvironment plays an important role in chemotherapeutic drug action.

Characterization of radical types, penetration profile and distribution pattern of the topically applied photosensitizer THPTS in porcine skin ex vivo.

The topical photodynamic therapy (PDT) is mainly used in the treatment of dermato-oncological diseases. The distribution and functionality of the photosensitizer Tetrahydroporphyrin-Tetratosylat (THPTS) was investigated using microscopic and spectroscopic methods after topical application to excised porcine skin followed by irradiation. The distribution of THPTS was determined by two-photon tomography combined with fluorescence lifetime imaging (TPT/FLIM) and confocal Raman microspectroscopy (CRM). The radicals were quantified and characterized by electron paramagnetic resonance (EPR) spectroscopy. Results show a penetration depth of THPTS into the skin down to around 12 ± 5 µm. A penetration of THPTS through the stratum corneum was not clearly observable after 1 h penetration time, but cannot be excluded. The irradiation within the phototherapeutic window (spectral range of visible and near infrared light in the range ≈ 650-850 nm) is needed to activate THPTS. An incubation time of 10 min showed the highest radical production. A longer incubation time affected the functionality of THPTS, whereby significant less radicals were detectable. During PDT mainly reactive oxygen species (ROS) and lipid oxygen species (LOS) are produced. Overall, the irradiation dose per se influences the radical types formed in skin. While ROS are always prominent at low doses, LOS increase at high doses, independent of previous skin treatment and the irradiation wavelength used.

Photodynamic effect of TPP encapsulated in polystyrene nanoparticles toward multi-resistant pathogenic bacterial strains: AFM evaluation.

Photodynamic inactivation (PDI) is a promising approach for the efficient killing of pathogenic microbes. In this study, the photodynamic effect of sulfonated polystyrene nanoparticles with encapsulated hydrophobic 5,10,15,20-tetraphenylporphyrin (TPP-NP) photosensitizers on Gram-positive (including multi-resistant) and Gram-negative bacterial strains was investigated. The cell viability was determined by the colony forming unit method. The results showed no dark cytotoxicity but high phototoxicity within the tested conditions. Gram-positive bacteria were more sensitive to TPP-NPs than Gram-negative bacteria. Atomic force microscopy was used to detect changes in the morphological properties of bacteria before and after the PDI treatment.

Bioorthogonal Pretargeting Strategy for Anchoring Activatable Photosensitizers on Plasma Membranes for Effective Photodynamic Therapy.

Developing novel activatable photosensitizers with excellent plasma membrane targeting ability is urgently needed for smart photodynamic therapy (PDT). Herein, a tumor acidity-activatable photosensitizer combined with a two-step bioorthogonal pretargeting strategy to anchor photosensitizers on the plasma membrane for effective PDT is developed. Briefly, artificial receptors are first anchored on the cell plasma membrane using cell-labeling agents (Az-NPs) via the enhanced permeability and retention effect to achieve the tumor cell labeling. Then, pH-sensitive nanoparticles (S-NPs) modified with dibenzocyclooctyne (DBCO) and chlorin e6 (Ce6) accumulate in tumor tissue and disassemble upon protonation of their tertiary amines in response to the acidic tumor environment, exposing the contained DBCO and Ce6. The selective, highly specific click reactions between DBCO and azide groups enable Ce6 to be anchored on the tumor cell surface. Upon laser irradiation, the cell membrane is severely damaged by the cytotoxic reactive oxygen species, resulting in remarkable cellular apoptosis. Taken together, the membrane-localized PDT by our bioorthogonal pretargeting strategy to anchor activatable photosensitizers on the plasma membrane provides a simple but effective method for enhancing the therapeutic efficacy of photosensitizers in anticancer therapy.

Multifunctional nanoparticle PEG­Ce6­Gd for MRI­guided photodynamic therapy.

Gliomas are one of the most common types of primary brain tumors. Despite recent advances in the combination of surgery, radiotherapy, systemic therapy (chemotherapy, targeted therapy) and supportive therapy in the multimodal treatment of gliomas, the overall prognosis remains poor and the long­term survival rate is low. Thus, it is crucial to develop a novel glioma management method. Due to its relatively non­invasive, selective and repeatable characteristics, photodynamic therapy (PDT) has been investigated for glioma therapy in the past decade, exhibiting higher selectivity and lower side effects compared with those of conventional therapy. However, most of the photosensitizers (PSs) are highly hydrophobic, leading to poor water solubility, rapid degradation with clearance in blood circulation and ultimately, low bioavailability. In the present study, hydrophilic polyethylene glycol (PEG)­chlorin e6 (Ce6) chelated gadolinium ion (Gd3+) nanoparticles (PEG­Ce6­Gd NPs) were synthesized via a chelation and self­assembly process. Initially, the cell cytotoxicity of PEG­Ce6­Gd NPs was evaluated with or without laser irradiation. The in vitro study demonstrated the lack of toxicity of PEG­Ce6­Gd NPs to tumor cells in the absence of laser irradiation. However, its toxicity was enhanced under laser irradiation. Moreover, the size and weight of brain tumors were significantly decreased in mice with glioma xenografts, which was further confirmed via histological analysis. Subsequently, the results indicated that the PEG­Ce6­Gd NPs had a favorable T1­weighted contrast performance (0.43 mg ml­1 s­1) and were observed to have significant contrast enhancement at the tumor site from 0.25 to 1 h post­injection in vivo. The favorable MRI, as well as the synergetic photodynamic antitumor effect and antineoplastic ability of PEG­Ce6­Gd NPs was identified. It was suggested that PEG­Ce6­Gd NPs had great potential in the diagnosis and PDT treatment of gliomas, and possibly other cancer types, with prospects of clinical application in the near future.

Combination of talaporfin photodynamic therapy and Poly (ADP-Ribose) polymerase (PARP) inhibitor in gastric cancer.

Photodynamic therapy (PDT) utilizes photochemical reactions induced by a photosensitizer and light in the target tissue and is used to treat various cancers. There is a high degree of anticipation of success regarding the application of PDT with talaporfin (photosensitizer) for gastric cancer. Olaparib is an oral inhibitor of Poly (ADP-Ribose) polymerase (PARP) and has demonstrated optimal efficacy and clinical activity in trials. Therefore, the aim of the present study was to investigate the efficacy of talaporfin PDT combined with olaparib for gastric cancer. MKN45, a gastric cancer cell line, was incubated with talaporfin, followed by irradiation, in the presence/absence of olaparib. Talaporfin PDT and olaparib exhibited excellent synergistic action in a concentration-dependent manner. PARP-DNA complexes were characterized based on bound chromatin using Western blot analyses. The combination of talaporfin PDT and olaparib enhanced PARP1 accumulation (the entrapment of PARP1-DNA complexes) in bound chromatin. The combination of talaporfin PDT and olaparib induced DNA double-strand breaks, which was confirmed by evaluating phosphorylated histone H2AX. Xenograft tumor mouse models were established, and antitumor effects were analyzed. In vivo, tumor growth was significantly suppressed following PDT with talaporfin and olaparib. Our results demonstrated that olaparib enhances the efficacy of talaporfin PDT by inducing the formation of PARP-DNA complexes. Therefore, our results suggest that the combination of talaporfin PDT and olaparib is a potential antitumor therapy for gastric cancer.

Comparison of the Photodynamic Action of Porphyrin, Chlorin, and Isobacteriochlorin Derivatives toward a Melanotic Cell Line.

Melanoma is the most dangerous form of skin cancer, with an abrupt growth of its incidence over the last years. It is extremely resistant to traditional treatments such as chemotherapy and radiotherapy, but therapies for this cancer are gaining attention. Photodynamic therapy (PDT) is considered an effective modality to treat several types of skin cancers and can offer the possibility to treat one of the most aggressive ones: melanoma. In this work, the effect of PDT on a melanotic cell line (B16F10 cells) was assessed by exposing cultured cells to 5,10,15-tris(pentafluorophenyl)-20-(4-pyridyl)porphyrin (PS1) and to its chlorin (PS2) and isobacteriochlorin (PS3) corresponding derivatives and red LED light (λ = 660 ± 20 nm). The PDT effect in the cells' viability was measured using the MTT assay. The cell apoptosis was quantified by flow cytometry, and the subcellular localization of the photosensitizer was determined by fluorescence microscopy. In addition, the ability of PS2 to generate superoxide radicals was qualitatively assessed by tyrosine nitration. The results show that the efficiency of the PDT process is dependent on the structure of the PS and on their ability to produce singlet oxygen. Besides that, the photoactivation efficiency is highly dependent on the cellular sublocalization of the PS and on its cellular uptake and singlet oxygen production. We also found that the resistant cell line B16F10 has distinctive chlorin, isobacteriochlorin, or porphyrin-specific resistance profiles. Furthermore, it is shown that the highly fluorescent chlorin derivative PS2 can also be considered in imaging diagnostics.

Self-assembly supramolecular drug delivery system for combination of photodynamic therapy and chemotherapy.

AIMS: To construct a self-assembly supramolecular drug delivery system (DDS) to co-deliver chlorin e6 (Ce6) and tripeptide tyroseroleutide (YSL) and evaluate the anti-tumour effects. METHODS: A supramolecular DDS was constructed via self-assembly of Ce6 and YSL based on π-π stacking and hydrogen-bond interaction. The size, morphology, stability, in vitro drug release, cellular uptake, cytotoxicity, pharmacokinetics analysis and pharmacodynamics analysis were respectively studied. RESULTS: Ce6-YSL nanoparticles with a uniform size of 75 ± 3.5 nm (PDI = 0.128) and monodispersed spherical morphology were constructed. The nanoparticles exhibited good stability with zeta potential -21.2 ± 1.73 mV. Under the weak acidic conditions, the accumulative drug release was 82.8% (w/w) (pH = 6.0) and 91.5% (w/w) (pH = 5.0), respectively, indicating that nanoparticles performed smart responsive properties and achieved controlled release characteristics in acidic tumour microenvironment. In addition, nanoparticles could easily enter the tumour cells and induce ROS production and inhibit cell proliferation in SMMCC-7721 cells with IC50 value 3.4 ± 0.023 µg/mL under laser irradiation. Furthermore, the nanoparticles could retain a much higher blood concentration in vivo and displayed excellent antitumor effect in tumour-bearing mice, showing no influence on body weight. CONCLUSIONS: This self-assembly supramolecular DDS can be used for combination of photodynamic therapy and chemotherapy in future research.

Structural requirement of G-quadruplex/aptamer-combined DNA macromolecule serving as efficient drug carrier for cancer-targeted drug delivery.

Photodynamic therapy (PDT) as a clinical cancer treatment method has been used to treat carcinomas in different organs, and G-quadruplex-based DNA nanocompartments serving as the carriers of cationic porphyrin photosensitizers, especially combined with cell-targeting aptamers, is considered to offer new opportunities for future cancer treatment. However, the structural features of G-quadruplex/aptamer complexes suitable for the capsulation of photosensitizers and target cell recognition is unexplored so far. In this study, unimolecular (UM), bimolecular (BM) and tetramolecular (TM) G-quadruplex structures were used as the drug loading compartments and grafted onto tumor cell-targeting aptamer Sgc8, constructing several targeting drug delivery vehicles (T-GMVs). Besides the binding affinity of resulting DNA architectures for target cells and cell recognition specificity were explored in a comparative fashion, the drug loading capability and cancer therapy efficacy were evaluated using TMPyP4 as the model porphyrin-based drug. The experimental results show that only TM G-quadruplex structure is suitable to combine with Sgc8 for the development of drug delivery vehicle and the as-prepared T-GMV- TMPyP4 complexes display the desirable cancer therapy efficacy, holding the potential application in the future cancer therapy. More importantly, T-GMV- TMPyP4 is expected to lay the scientific groundwork for the successful development of G-quadruplex-based photosensitizer drug delivery carriers for the targeted cancer therapy.

In Vitro Photodynamic Effects of the Inclusion Nanocomplexes of Glucan and Chlorin e6 on Atherogenic Foam Cells.

Macrophage-derived foam cells play critical roles in the initiation and progression of atherosclerosis. Activated macrophages and foam cells are important biomarkers for targeted imaging and inflammatory disease therapy. Macrophages also express the dectin-1 receptor, which specifically recognizes ß-glucan (Glu). Here, we prepared photoactivatable nanoagents (termed Glu/Ce6 nanocomplexes) by encapsulating hydrophobic chlorin e6 (Ce6) within the triple-helix structure of Glu in aqueous condition. Glu/Ce6 nanocomplexes generate singlet oxygen upon laser irradiation. The Glu/Ce6 nanocomplexes were internalized into foam cells and delivered Ce6 molecules into the cytoplasm of foam cells. Upon laser irradiation, they induced significant membrane damage and apoptosis of foam cells. These results suggest that Glu/Ce6 nanocomplexes can be a photoactivatable material for treating atherogenic foam cells.

Amphiphilic block polymer-based self-assembly of high payload nanoparticles for efficient combinatorial chemo-photodynamic therapy.

Combinatorial chemo-photodynamic therapy is regared as effective cancer therapy strategy, which could be realized via multiple nano-drug delivery system. Herein, novel high payload nanoparticles stabilized by amphiphilic block polymer cholesterol-b-poly(ethylene glycol) (PEG)2000 (Chol-PEG2000) were fabricated for loading chemotherapeutic drug 10-hydroxycamptothecin (HCPT) and photosensitizer chlorin e6 (Ce6). The obtained HCPT/Ce6 NPs showed uniform rod-like morphology with a hydration diameter of 178.9 ± 4.0 nm and excellent stability in aqueous solution. HCPT and Ce6 in the NPs displayed differential release profile, which was benefit for preferentially exerting the photodynamic effect and subsequently enhancing the sensitivity of the cells to HCPT. Under laser irradiation, the NPs demonstrated fantastic in vitro and in vivo anticancer efficiency due to combinational chemo-photodynamic therapy, enhanced cellular uptake effectiveness, and superb intracellular ROS productivity. Besides, the NPs were proved as absent of systemic toxicity. In summary, this nanoparticle delivery system could be hopefully utilized as effective cancer therapy strategy for synergistically exerting combined chemo-photodynamic therapy in clinic.

Hemoglobin-mediated biomimetic synthesis of paramagnetic O2-evolving theranostic nanoprobes for MR imaging-guided enhanced photodynamic therapy of tumor.

The hypoxic microenvironment in solid tumors severely limits the efficacy of photodynamic therapy (PDT). Therefore, the development of nanocarriers co-loaded with photosensitizers and oxygen, together with imaging guidance ability, is of great significance in cancer therapy. However, previously reported synthetic methods for these multi-functional probes are complicated, and the raw materials used are toxic. Methods: Herein, the human endogenous protein, hemoglobin (Hb), was used for the simultaneous biomimetic synthesis of Gd-based nanostructures and co-loading of Chlorine e6 (Ce6) and oxygen for alleviating the hypoxic environment of tumors and accomplishing magnetic resonance imaging (MRI)-guided enhanced PDT. The Gd@HbCe6-PEG nanoprobes were synthesized via a green and protein biomimetic approach. The physicochemical properties, including relaxivity, oxygen-carrying/release capability, and PDT efficacy of Gd@HbCe6-PEG, were measured in vitro and in vivo on tumor-bearing mice after intravenous injection. Morphologic and functional MRI were carried out to evaluate the efficacy of PDT. Results: The results demonstrated the successful synthesis of compact Gd@HbCe6-PEG nanostructures with desired multi-functionalities. Following treatment with the nanoparticles, the embedded MR moiety was effective in lighting tumor lesions and guiding therapy. The oxygen-carrying capability of Hb after biomimetic synthesis was confirmed by spectroscopic analysis and oxygen detector in vitro. Further, tumor oxygenation for alleviating tumor hypoxia in vivo after intravenous injection of Gd@HbCe6-PEG was verified by photoacoustic imaging and immunofluorescence staining. The potent treatment efficacy of PDT on early-stage was observed by the morphologic and functional MR imaging. Importantly, rapid renal clearance of the particles was observed after treatment. Conclusion: In this study, by using a human endogenous protein, we demonstrated the biomimetic synthesis of multi-functional nanoprobes for simultaneous tumor oxygenation and imaging-guided enhanced PDT. The therapeutic efficacy could be quantitatively confirmed at 6 h post PDT with diffusion-weighted imaging (DWI).

Nano-delivery vehicle based on chlorin E6, photodynamic therapy, doxorubicin chemotherapy provides targeted treatment of HER-2 negative, ανß3-positive breast cancer.

The prognosis for patients with HER-2 negative breast cancer is currently poor, largely due to the lack of efficacious targeted therapeutics. Photodynamic nanomaterial technologies have rapidly developed in recent years, but their anti-tumor effects are often limited by poor targeting, low transformation efficiency, toxicity, and other factors. Thus, we prepared a new type of nanoparticles (Ce6/Dox@NPs-cRGD, CDNR) with cyclo(Arg-Gly-Asp-d-Phe-Cys) (c(RGDfC)) that target the ανß3 receptor. We loaded those nanoparticles (NPs) with a combination of the doxorubicin (Dox) and photosensitizer chlorin E6 (Ce6) to test synergy between chemotherapy and photodynamic therapy (PDT) for the treatment of ανß3 receptor positive and HER-2 negative breast cancer. Through analysis of the Fourier transform infrared and UV-vis spectra of these NPs, we found that Ce6 and Dox were successfully loaded into the CDNR. According to dynamic light scattering (DLS) analyses, CDNR particles had a diameter of 112.6 nm (polydispersity index 0.11), which was also confirmed via TEM characterization. The zeta potential was about -21.5 mV. Stability studies showed that CDNR particle size was stable in ddH2O, PBS, and DMEM + 5 % FBS for 16 days. The drug loading content of Dox and Ce6 were 5.3 and 6.8 %, respectively. Release studies of CDNR showed that the slow release of Dox was accelerated with increasing GSH concentration, and there was no burst release effect. From studying the absorbance of 9,10-dimethylanthrancene (ABDA), we found that CDNR produces high levels of ROS after excitation with a 670 nm laser, and ROS production increased with increasing radiation time. CDNR was significantly taken up by MCF-7 cells at 6 h because of cRGD targeting. In a CCK8 test, the relative growth rate (RGR) of CDNR +670 nm laser for MCF-7 cells was less than 75 % at 20 µg/mL after 24 h treatment and 15 µg/mL after 48 h treatment. We found that CDNR's effects on RGR were concentration dependent. Live-cell staining with a DCFH-DA kit and flow cytometry assay further supported that a CDNR +670 nm laser provided the maximum chemotherapy-PDT toxicity and production of intracellular ROS, and that cell death was mainly caused by necrosis and apoptosis. In vivo experiments showed that using the cRGD-targeting strategy, CDNR had a stronger affinity and increased half-life relative to Ce6/Dox@NPs in mice with MCF-7 xenograft tumors. Further, the Cmax of CDNR in the transplanted tumor occurred 8 h post-injection (HPI) and there was still detectable signal at 24 HPI. In addition, MCF-7 bearing mice that were treated with CDNR +670 nm PDT at 8 HPI had a significantly decreased tumor volume (P < 0.05) and prolonged survival time compared to other groups. Thus, CDNR plus 670 nm PDT was associated with favorable anti-tumor activity with no appreciable impact on body weight or the major organs in mice, as determined by immunohistochemistry/immunofluorescence and hematoxylin-eosin staining. In conclusion, CDNR with 670 nm laser irradiation represents a promising new potential treatment paradigm for the management of breast cancers that are ανß3-receptor positive and HER-2 negative.

Guiding Appropriate Timing of Laser Irradiation by Polymeric Micelles for Maximizing Chemo-Photodynamic Therapy.

BACKGROUND: Photoactivity "on-off" switchable nano-agents could shield phototoxicity until reaching target region, which immensely promoted photodynamic therapy. However, the masking ratio of nano-agents in vivo was dynamic and positively correlated with the phototoxicity induced by laser irradiation, in which case the timing of laser irradiation was unpredictable to maximize antitumor efficacy. METHODS: Herein, low molecular weight chitosan and hydrophobic polymethylacrylamide derivatives were linked via GSH cleavable 3, 3'-dithiodipropionic acid to construct polymeric micelles (Ce6-CSPD). The doxorubicin loading nano-agent (Ce6-CSPD/DOX) could quench both photoactivity and fluorescence of photosensitizer chlorin e6 (Ce6) and doxorubicin (DOX) under physiological condition by homo-fluorescence resonance energy transfer (homoFRET). RESULTS: Once internalized by tumor cells, the photoactivity as well as fluorescence of Ce6 was recovered rapidly when motivated by intracellular high GSH. Specifically, the fluorescence intensity and photoactivity of Ce6 were proven to be positive linear correlated, upon which appropriate timing of laser irradiation could be determined by referring to the dynamic fluorescence intensity in vivo. In addition, the theranostic nano-agents also possessed the capacity of monitoring the DOX release process. Accordingly, under the guidance of fluorescence intensity, the experimental group subjected to laser irradiation at 18 h postadministration acquired the highest antitumor inhibition efficacy compared to that at four hours and 48 h, which held great potential for maximizing chemo-photodynamic therapy and avoiding nonspecific phototoxicity precisely to normal organs. CONCLUSION: In summary, we prepared homoFRET-based theranostic nano-agent (Ce6-CSPD/DOX) for monitoring PDT precisely and decreasing phototoxicity to normal organs before reaching target region. Under the guidance of dynamic fluorescence intensity, the appropriate laser irradiation timing could be monitored to maximize antitumor therapy efficacy, which offered opportunities for monitoring efficiency of chemo-photodynamic therapy in a timely and accurate manner.

Bioactive Natural Small Molecule-Tuned Coassembly of Photosensitive Drugs for Highly Efficient Synergistic and Enhanced Type I Photochemotherapy.

Self-assembling natural small molecules (NSMs) with favorable anticancer activity are of increasing interest as novel drug delivery platforms without structural modification for biomedical applications. However, a lack of knowledge and practicability of NSMs as drug carriers limited their current biomedical application. Here, via a green and facile supramolecular coassembly strategy, we report and develop a series of carrier-free terpenoid natural small molecule-mediated coassembled photosensitive drugs for enhanced and synergistic chemo/photodynamic therapy. After screening 17 terpenoid NSMs, we identified 11 compounds that could form coassembled NSMs-Ce6 NPs with regulatable drug sizes. Analysis of the representative betulonic acid (BC)-mediated nano-coassemblies (BC-Ce6 NPs) reveals the high efficiency of the coassembly strategy and highlights the tremendous potential of NSMs as novel drug delivery platforms. Through molecular dynamics simulation and theoretical calculations, we elucidate the mystery of the coassembly process, indicating that the linear coplanar arrangement of BC dimeric units is primarily responsible for the formation of rod-like or spherical morphology. Meanwhile, we demonstrated that the reduced energy gap between the singlet and triplet excited states (ΔEST) facilitates efficient reactive oxygen species generation by promoting ·OH generation via a type I photoreaction mechanism. The assembled nanodrugs exhibit multiple favorable therapeutic features, ensuring a remarkably enhanced, synergistic, and secure combinatorial anticancer efficacy of 93.6% with highly efficient tumor ablation. This work not only expands the possibility of natural biodegradable materials for wide biological applications but also provides a new perspective for the construction of NSM-mediated nano-coassemblies for precision therapy.

Topical application of Chlorin e6-PVP (Ce6-PVP) for improved endoscopic detection of neoplastic lesions in a murine colitis-associated cancer model.

Screening colonoscopy is crucial in reducing the mortality of colorectal cancer. However, detecting adenomas against the backdrop of an inflamed mucosa (e.g. in ulcerative colitis) remains exceedingly difficult. Therefore, we aimed to improve neoplastic lesion detection by employing a fluorescence-based endoscopic approach. We used the well-established murine AOM/DSS model to induce inflammation-driven carcinogenesis in the colon. In our diagnostic approach, we evaluated Chlorin e6 polyvinylpyrrolidone (Ce6-PVP)-based fluorescence endoscopy in comparison to standard white-light endoscopy. A specialized pathologist then analyzed the histology of the detected lesions. Complementary in vitro studies were performed using human cell lines and a murine organoid system. Ce6-PVP-based fluorescence endoscopy had an improved detection rate of 100% (8/8) in detecting high-grade dysplasias and carcinomas over white-light detection alone with 75% (6/8). Trade-off for this superior detection rate was an increased rate of false positive lesions with an increase in the false discovery rate from 45% for white-light endoscopy to 81% for fluorescence endoscopy. We demonstrate in a proof-of-concept study that Ce6-PVP-based fluorescence endoscopy is a highly sensitive red flag technology to identify biopsy-worthy lesions in the colon.