Chlorin e6-Encapsulated Polyphosphoester Based Nanocarriers with Viscous Flow Core for Effective Treatment of Pancreatic Cancer

Wireless sequential dual light delivery for programmed PDT in vivo

Using photodynamic therapy (PDT) to treat deep-seated cancers is limited due to inefficient delivery of photosensitizers and low tissue penetration of light. Polymeric nanocarriers are widely used for photosensitizer delivery, while the self-quenching of the encapsulated photosensitizers would impair the PDT efficacy. Furthermore, the generated short-lived reactive oxygen spieces (ROS) can hardly diffuse out of nanocarriers, resulting in low PDT efficacy. Therefore, a smart nanocarrier system which can be degraded by light, followed by photosensitizer activation can potentially overcome these limitations and enhance the PDT efficacy. A light-sensitive polymer nanocarrier encapsulating photosensitizer (RB-M) was synthesized. An implantable wireless dual wavelength microLED device which delivers the two light wavelengths sequentially was developed to programmatically control the release and activation of the loaded photosensitizer. Two transmitter coils with matching resonant frequencies allow activation of the connected LEDs to emit different wavelengths independently. Optimal irradiation time, dose, and RB-M concentration were determined using an agent-based digital simulation method. In vitro and in vivo validation experiments in an orthotopic rat liver hepatocellular carcinoma disease model confirmed that the nanocarrier rupture and sequential low dose light irradiation strategy resulted in successful PDT at reduced photosensitizer and irradiation dose, which is a clinically significant event that enhances treatment safety.

Light-responsive smart nanocarriers for wirelessly controlled photodynamic therapy for prostate cancers

Photodynamic therapy (PDT) is an effective non-invasive or minimally invasive treatment method against different tumors. Loading photosensitizers in nanocarriers can potentially increase their accumulation in tumor sites. However, the PDT efficacy may be hindered because of self-quenching of the encapsulated photosensitizer and the small diffusion radii of the generated reactive oxygen species (ROS). Herein, light responsive nano assemblies composed of (Polyethylene glycol)-block-poly(4,5-dimethoxy-2-nitrobenzylmethacrylate) (PEG-b-PNBMA) were designed and loaded with the photosensitizer, Rose Bengal lactone (RB), to act as a smart nanocarrier (RB-M) for the delivery of the photosensitizer. A wirelessly activated light-emitting diode (LED) implant was designed to programmatically induce the release of the loaded RB first, followed by activating PDT after diffusion of RB into the cytoplasm. The results showed that sequential '405-580 nm' irradiation of the RB-M treated 22RV1 cells resulted in the highest PDT outcome among different irradiation protocols. The combination of this smart nanocarrier and sequential '405-580 nm' irradiation strategy exhibited good PDT efficacy against 2D 22RV1 prostate cancer cells as well as 3D cancer cell spheroids. This platform overcomes the light penetration limitations in PDT, and can potentially be applied in cancer bearing patients who are unfit for chemotherapy. STATEMENT OF SIGNIFICANCE: Nanocarriers for the delivery of photosensitizer in photodynamic therapy may result in relatively low therapeutic efficacy because of self-quenching of the encapsulated photosensitizer and the small diffusion radii of the generated reactive oxygen species (ROS). Light responsive smart nanocarriers can potentially overcome this challenge. In this study, a light responsive polymer (Polyethylene glycol)-block-poly(4,5-dimethoxy-2-nitrobenzylmethacrylate) (PEG-b-PNBMA) was synthesized and utilized to fabricate the smart nanocarrier. A wirelessly activated light-emitting diode (LED) implant was designed for light delivery in deep tissue. This new approach permits wirelessly and programmatically control of photosensitizer release and PDT activation under deep tissue, thus significantly enhancing PDT efficacy against prostate cancer cells as well as 3D cancer cell spheroids. This design should have a significant impact on controllable PDT under deep tissue.

Chlorin e6: A Promising Photosensitizer in Photo-Based Cancer Nanomedicine

Conventional cancer treatment modalities are often associated with major therapeutic limitations and severe side effects. Photodynamic therapy is a localized noninvasive mode of treatment that has given a different direction to cancer research due to its effectivity against a wide range of cancers and minimal side effects. A photosensitizer is the key component of photodynamic therapy (PDT) that generates cytotoxic reactive oxygen species to eradicate cancer cells. As the therapeutic effectivity of PDT greatly depends upon the photosensitizer, great efforts have been made to search for an ideal photosensitizer. Chlorin e6 is a FDA approved second generation photosensitizer that meets the desired clinical properties for PDT. It is known for its high reactive oxygen species (ROS) generation ability and anticancer potency against many types of cancer. Hydrophobicity is a major drawback of Ce6 that leads to its poor biodistribution and rapid clearance from the circulatory system. To overcome this drawback, researchers have designed and fabricated several types of nanosystems, which can enhance Ce6 solubility and thereby enhance its bioavailability. These nanosystems also improve tumor accumulation of Ce6 by selectively targeting the cancer cells through passive and active targeting. In addition, Ce6 has been employed in many combination therapies like chemo-photodynamic therapy, photoimmunotherapy, and combined photodynamic-photothermal therapy. A combination therapy is more curative than a single therapy due to the synergistic effects of individual therapies. Ce6-based nanosystems for combination therapies have shown excellent results in various studies and provide a promising platform for cancer treatment.

Effect of Photodynamic Therapy with Chlorin e6 on Canine Tumors

This work aims to prepare pure Chlorin e6 (Ce6) and establish Ce6-mediated photodynamic therapy (Ce6-PDT) as a better therapy option for canine tumors as well as mouse tumor models. Five dogs suffering from various cancers were treated with Ce6-PDT from one to several times. After receiving the Ce6 (2.5 mg/kg) for 3 h, tumors were illuminated superficially or interstitially with 660 nm light. Two dogs underwent Ce6-guided fluorescence imaging by photodynamic diagnosis (PDD). Cell proliferation and apoptosis were detected by the 4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay and western blot assay, respectively. Ce6-PDT efficacy was also determined using melanoma and pancreatic cancer mouse models. Two veterinary patients with mammary carcinoma and histiocytic sarcoma had their tumors significantly diminished and showed improved health after receiving Ce6-PDT. Moreover, in the cases of canine tumors, the adjunctive use of Ce6-PDD revealed cancers that were not visible with white light viewing and provided a visual contrast from surrounding tissues. Also, in vivo, Ce6-PDT remarkably reduced melanoma and pancreatic tumors in the mouse model. These findings could pave the way for a better understanding of the underlying processes of Ce6-PDT, making it an effective and safe candidate for use in human and veterinary applications to abolish various cancers.

NIR-Triggered and ROS-Boosted Nanoplatform for Enhanced Chemo/PDT/PTT Synergistic Therapy of Sorafenib in Hepatocellular Carcinoma

Although being the first-line treatment of advanced hepatocellular carcinoma (HCC), sorafenib (SOR) outcome is limited due to drug resistance and low tumor accumulation. Herein, with MnO₂ as photothermal agent and chlorine6 (Ce6) as photosensitizer, a tumor-targeting and NIR-triggered multifunctional nanoplatform loading sorafenib (MnO₂-SOR-Ce6@PDA-PEG-FA, MSCPF) was constructed. Owing to oxygen generator MnO₂, MSCPF could generate excessive ROS, thus can alleviate tumor hypoxia and improve sorafenib accumulation in cancer cells. Besides, ROS production further strengthens Ce6-mediated PDT and PDA-mediated PTT. By exploiting these features, MSCPF exhibited excellent antitumor effects on HCC in the in vitro and in vivo studies, compared to solo sorafenib or PDT/PTT treatment. Further mechanism experiments suggested that MSCPF could inhibit P-gp expression and induce ferroptosis via deactivation of GPX4 and SLC7A11, which ultimately enhanced the antitumor efficacy of SOR. In summary, our work highlights a promising NIR-triggered and ROS-boosted nanoplatform for enhanced chemo/PDT/PTT synergistic therapy of SOR in HCC treatment.

Recent advances in the development of biocompatible nanocarriers and their cancer cell targeting efficiency in photodynamic therapy

In recent years, the role of biocompatible nanocarriers (BNs) and their cancer cell targeting efficiency in photodynamic therapy (PDT) holds potential benefits for cancer treatment. Biocompatible and biodegradable nanoparticles are successfully used as carrier molecules to deliver cancer drugs and photosensitizers due to their material safety in the drug delivery system. Biocompatible nanocarriers are non-toxic and ensure high-level biocompatibility with blood, cells, and physiological conditions. The physicochemical properties of BNs often enable them to modify their surface chemistry, which makes conjugating specific ligands or antibodies to achieve cancer cell targeting drug delivery in PDT. This review article focuses on the various types of BNs used in targeted drug delivery, physicochemical properties, and surface chemistry of BNs in targeted drug delivery, advantages of BNs in drug delivery systems, and the targeting efficiency of BNs on some specific targeting receptors for cancer therapy. Furthermore, the review briefly recaps the nanocarrier-based targeted approaches in cancer PDT.

Photosensitizer Nanoparticles Boost Photodynamic Therapy for Pancreatic Cancer Treatment

Patients with pancreatic cancer (PCa) have a poor prognosis apart from the few suitable for surgery. Photodynamic therapy (PDT) is a minimally invasive treatment modality whose efficacy and safety in treating unresectable localized PCa have been corroborated in clinic. Yet, it suffers from certain limitations during clinical exploitation, including insufficient photosensitizers (PSs) delivery, tumor-oxygenation dependency, and treatment escape of aggressive tumors. To overcome these obstacles, an increasing number of researchers are currently on a quest to develop photosensitizer nanoparticles (NPs) by the use of a variety of nanocarrier systems to improve cellular uptake and biodistribution of photosensitizers. Encapsulation of PSs with NPs endows them significantly higher accumulation within PCa tumors due to the increased solubility and stability in blood circulation. A number of approaches have been explored to produce NPs co-delivering multi-agents affording PDT-based synergistic therapies for improved response rates and durability of response after treatment. This review provides an overview of available data regarding the design, methodology, and oncological outcome of the innovative NPs-based PDT of PCa.

A PEGylated photosensitizer-core pH-responsive polymeric nanocarrier for imaging-guided combination chemotherapy and photodynamic therapy

A novel chemo-photodynamic combined therapeutic self-assembly polymeric platform (MPEG-Hyd-Br₂-BODIPY) was constructed which can encapsulate DOX and exhibited an accelerated release rate with decreasing pH value which results in considerable time/dose-dependent cytotoxicity.

Coupling Chlorin e6 to the surface of Nanoscale Gas Vesicles strongly enhance their intracellular delivery and photodynamic killing of cancer cells

Protein-based nanobubbles such as halophilic archaeabacterial gas vesicles (GVs) represent a new class of stable, homogeneous nanoparticles with acoustic properties that allow them to be visualized by ultrasound (US) waves. To design GVs as theranostic agents, we modified them to respond to light, with a view to locally generate reactive oxygen species that can kill cancer cells. Specifically, up to 60,000 photoreactive chlorin e6 (Ce6) molecules were chemically attached to lysine ε-amino groups present on the surface of each purified Halobacterium sp. NRC-1 GV. The resulting fluorescent NRC-1 Ce6-GVs have dimensions comparable to that of native GVs and were efficiently taken up by human breast [MCF-7] and human hypopharyngeal [FaDu-GFP] cancer cells as monitored by confocal microscopy and flow cytometry. When exposed to light, internalized Ce6-GVs were 200-fold more effective on a molar basis than free Ce6 at killing cells. These results demonstrate the potential of Ce6-GVs as novel and promising nanomaterials for image-guided photodynamic therapy.

Porphyrinoid-based photosensitizers for diagnostic and therapeutic applications: An update

Porphyrin-based molecules are actively studied as dual function theranostics: fluorescence-based imaging for diagnostics and fluorescence-guided therapeutic treatment of cancers. The intrinsic fluorescent and photodynamic properties of the bimodal molecules allows for these theranostic approaches. Several porphyrinoids bearing both hydrophilic and/or hydrophobic units at their periphery have been developed for the aforementioned applications, but better tumor selectivity and high efficacy to destroy tumor cells is always a key setback for their use. Another issue related to their effective clinical use is that, most of these chromophores form aggregates under physiological conditions. Nanomaterials that are known to possess incredible properties that cannot be achieved from their bulk systems can serve as carriers for these chromophores. Porphyrinoids, when conjugated with nanomaterials, can be enabled to perform as multifunctional nanomedicine devices. The integrated properties of these porphyrinoid-nanomaterial conjugated systems make them useful for selective drug delivery, theranostic capabilities, and multimodal bioimaging. This review highlights the use of porphyrins, chlorins, bacteriochlorins, phthalocyanines and naphthalocyanines as well as their multifunctional nanodevices in various biomedical theranostic platforms.

An enzyme-responsive membrane for antibiotic drug release and local periodontal treatment

Periodontitis is a chronic, destructive inflammatory disease that injures tooth- supporting tissues, eventually leading to tooth loss. Complete eradication of periodontal pathogenic microorganisms is fundamental to allow periodontal healing and commonly precedes periodontal tissue regeneration. To address this challenge, we report a strategy for developing an enzyme-mediated periodontal membrane for targeted antibiotic delivery into infectious periodontal pockets; the unique components of the membrane will also benefit periodontal alveolar bone repair. In this approach, a chitosan membrane containing polyphosphoester and minocycline hydrochloride (PPEM) was prepared. Physical, morphological, and ultrastructural analyses were carried out in order to assess cellular compatibility, drug release and antibacterial activity in vitro. Additionally, the functionality of the PPEM membrane was evaluated in vivo with a periodontal defect model in rats. The results confirm that the PPEM membrane exhibits good physical properties with excellent antibacterial activity and successfully promotes periodontal tissue repair, making it promising for periodontal treatment.

Photoactive Liposomal Formulation of PVP-Conjugated Chlorin e6 for Photodynamic Reduction of Atherosclerotic Plaque

Background: Liposomes serve as delivery systems for biologically active compounds. Existing technologies inefficiently encapsulate large hydrophilic macromolecules, such as PVP-conjugated chlorin e6 (Photolon). This photoactive drug has been widely tested for therapeutic applications, including photodynamic reduction of atherosclerotic plaque. Methods: A novel formulation of Photolon was produced using “gel hydration technology”. Its pharmacokinetics was tested in Sus scrofa f. domestica. Its cellular uptake, cytotoxicity, and ability to induce a phototoxic reaction were demonstrated in J774A.1, RAW264.7 macrophages, and vascular smooth muscle (T/G HA-VSMC) as well as in vascular endothelial (HUVEC) cells. Results: Developed liposomes had an average diameter of 124.7 ± 0.6 nm (polydispersity index (PDI) = 0.055) and contained >80% of Photolon). The half-life of formulation in S. scrofa was 20 min with area under the curve (AUC) equal to 14.7. The formulation was noncytotoxic in vitro and was rapidly (10 min) and efficiently accumulated by macrophages, but not T/G HA-VSMC or HUVEC. The accumulated quantity of photosensitizer was sufficient for induction of phototoxicity in J774A.1, but not in T/G HA-VSMC. Conclusions: Due to the excellent physical and pharmacokinetic properties and selectivity for macrophages, the novel liposomal formulation of Photolon is a promising therapeutic candidate for use in arteriosclerosis treatment when targeting macrophages but not accompanying vascular tissue is critical for effective and safe therapy.

Polyphosphoester-Based Nanocarrier for Combined Radio-Photothermal Therapy of Breast Cancer

Recently, clinical research on tumor therapy has gradually shifted from traditional monotherapy toward combination therapy as tumors are complex, diverse, and heterogeneous. Combination therapy may be essential for achieving the optimized treatment efficacy of tumors through distinct tumor-inhibiting mechanisms. At the same time, nanocarriers are emerging as an excellent strategy for delivering both drugs simultaneously. This work presents utilization of a polyphosphoester-based nanocarrier (NP_IR/Cur) to achieve the codelivery of hydrophobic photothermal agent IR-780 and radiosensitizer curcumin (Cur). The IR-780 and curcumin coencapsulated NP_IR/Cur exhibited adequate drug loading, a prolonged blood half-life, enhanced passive tumor homing, and improved curcumin bioavailability as well as combined therapeutic functions. Briefly, NP_IR/Cur could not only achieve effective thermal ablation through the conversion of near-infrared light to heat, but also give rise to a significant boosted local radiation dose to trigger promoted radiation damages, thus resulting in enhanced tumor cell growth inhibition. In conclusion, the as-prepared NP_IR/Cur manifested excellent performance in facilitating combined photothermal and radiation therapy, thus expanding the application range of PPE-based carriers in nanomedicine, and also prompting exploration of their potential for other effective combination therapies.

Effect of photodynamic therapy with (17R,18R)-2-(1-hexyloxyethyl)-2-devinyl chlorine E6 trisodium salt on pancreatic cancer cells in vitro and in vivo

AIM

To investigate the antitumor effects and underlying mechanisms of (17R,18R)-2-(1-hexyloxyethyl)-2-devinyl chlorine E6 trisodium salt (YLG-1)-induced photodynamic therapy (PDT) on pancreatic cancer in vitro and in vivo.

METHODS

YLG-1 is a novel photosensitizer extracted from spirulina. Its phototoxicity, cellular uptake and localization, as well as its effect on reactive oxygen species (ROS) production, apoptosis, and expression of apoptosis-associated proteins were detected in vitro. An in vivo imaging system (IVIS), the Lumina K imaging system, and mouse models of subcutaneous Panc-1-bearing tumors were exploited to evaluate the drug delivery pathway and pancreatic cancer growth in vivo.

RESULTS

YLG-1 was localized to the mitochondria, and the appropriate incubation time was 6 h. Under 650 nm light irradiation, YLG-1-PDT exerted a potent cytotoxic effect on pancreatic cancer cells in vitro, which could be abolished by the ROS scavenger N-acetyl-L-cysteine (NAC). The death mode caused by YLG-1-PDT was apoptosis, accompanied by upregulated Bax and cleaved Caspase-3 and decreased Bcl-2 expression. The results from the IVIS images suggested that the optimal administration route was intratumoral (IT) injection and that the best time to conduct YLG-1-PDT was 2 h post-IT injection. Consistent with the results in vitro, YLG-1-PDT showed great growth inhibition effects on pancreatic cancer cells in a mouse model.

CONCLUSION

YLG-1 is a potential photosensitizer for pancreatic cancer PDT via IT injection, the mechanisms of which are associated with inducing ROS and promoting apoptosis.

Rational Design of IR820- and Ce6-Based Versatile Micelle for Single NIR Laser-Induced Imaging and Dual-Modal Phototherapy

Phototherapy as a promising cancer diagnostic and therapeutic strategy has aroused extensive attention. However, single-wavelength near-infrared (NIR) light-triggered combinational treatment of photothermal therapy (PTT) and photodynamic therapy (PDT) is still a great challenge. Herein, a multifunctional micelle activated by a single-wavelength laser for simultaneous PTT and PDT as well as fluorescence imaging is developed. Briefly, new indocyanine green (IR820) is conjugated to d-α-tocopheryl polyethylene glycol 1000 succinate (TPGS) via the linker 6-aminocaproic acid, and then, chlorin e6 (Ce6) is encapsulated into the micelles formed by TPGS-IR820 conjugates to fabricate TPGS-IR820/Ce6 micelles. As the well-designed TPGS-IR820 conjugate shares a similar peak absorption wavelength with Ce6, this micelle can be applied with a single NIR laser (660 nm). The stable micelles exhibit excellent photothermal conversion efficiency in vitro and in vivo as well as high singlet oxygen generation capacity in tumor cells. After efficient cellular internalization, the as-prepared micelles display outstanding anticancer activity upon single NIR laser irradiation in vitro and in vivo. Furthermore, TPGS-IR820/Ce6 micelles show negligible systemic toxicity. The highly safe and effective TPGS-IR820/Ce6 micelles can offer an innovative strategy to construct single NIR light-induced PTT and PDT combined phototherapy nanoplatforms via suitable modification of organic phototherapeutic agents.

Recent progress in the engineering of multifunctional colloidal nanoparticles for enhanced photodynamic therapy and bioimaging

This up-to-date review summarizes the design and current fabrication strategies that have been employed in the area of mono- and multifunctional colloidal nanoparticles - nanocarriers well suited for photodynamic therapy (PDT) and diagnostic purposes. Rationally engineered photosensitizer (PS)-loaded nanoparticles may be achieved via either noncovalent (i.e., self-aggregation, interfacial deposition, interfacial polymerization, or core-shell entrapment along with physical adsorption) or covalent (chemical immobilization or conjugation) processes. These PS loading approaches should provide chemical and physical stability to PS payloads. Their hydrophilic surfaces, capable of appreciable surface interactions with biological systems, can be further modified using functional groups (stealth effect) to achieve prolonged circulation in the body after administration and/or grafted by targeting agents (such as ligands, which bind to specific receptors uniquely expressed on the cell surface) or stimuli (e.g., pH, temperature, and light)-responsive moieties to improve their action and targeting efficiency. These attempts may in principle permit efficacious PDT, combination therapies, molecular diagnosis, and - in the case of nanotheranostics - simultaneous monitoring and treatment. Nanophotosensitizers (nano-PSs) should possess appropriate morphologies, sizes, unimodal distributions and surface processes to be successfully delivered to the place of action after systemic administration and should be accumulated in certain tumors by passive and/or active targeting. Additionally, physically facilitating drug delivery systems emerge as a promising approach to enhancing drug delivery, especially for the non-invasive treatment of deep-seated malignant tissues. Recent advances in nano-PSs are scrutinized, with an emphasis on design principles, via the promising use of colloid chemistry and nanotechnology.

Development of redox-responsive theranostic nanoparticles for near-infrared fluorescence imaging-guided photodynamic/chemotherapy of tumor

The development of imaging-guided smart drug delivery systems for combinational photodynamic/chemotherapy of the tumor has become highly demanded in oncology. Herein, redox-responsive theranostic polymeric nanoparticles (NPs) were fabricated innovatively using low molecular weight heparin (LWMH) as the backbone. Chlorin e6 (Ce6) and alpha-tocopherol succinate (TOS) were conjugated to LMWH via cystamine as the redox-sensitive linker, forming amphiphilic Ce6-LMWH-TOS (CHT) polymer, which could self-assemble into NPs in water and encapsulate paclitaxel (PTX) inside the inner core (PTX/CHT NPs). The enhanced near-infrared (NIR) fluorescence intensity and reactive oxygen species (ROS) generation of Ce6 were observed in a reductive environment, suggesting the cystamine-switched "ON/OFF" of Ce6. Also, the in vitro release of PTX exhibited a redox-triggered profile. MCF-7 cells showed a dramatically higher uptake of Ce6 delivered by CHT NPs compared with free Ce6. The improved therapeutic effect of PTX/CHT NPs compared with mono-photodynamic or mono-chemotherapy was observed in vitro via MTT and apoptosis assays. Also, the PTX/CHT NPs exhibited a significantly better in anti-tumor efficiency upon NIR irradiation according to the results of in vivo combination therapy conducted on 4T1-tumor-bearing mice. The in vivo NIR fluorescence capacity of CHT NPs was also evaluated in tumor-bearing nude mice, implying that the CHT NPs could enhance the accumulation and retention of Ce6 in tumor foci compared with free Ce6. Interestingly, the anti-metastasis activity of CHT NPs was observed against MCF-7 cells by a wound healing assay, which was comparable to LMWH, suggesting LMWH was promising for construction of nanocarriers for cancer management.

Acetal-Linked Hyperbranched Polyphosphoester Nanocarriers Loaded with Chlorin e6 for pH-Activatable Photodynamic Therapy

Nanocarrier-mediated photodynamic therapy (PDT), which involves the systemic delivery of photosensitizers (PSs) into tumor tissue and tumor cells, has emerged as an attractive treatment for cancer. However, insufficient PS release limits intracellular cytotoxic reactive oxygen species (ROS) generation, which has become a major obstacle to improving the PDT therapeutic efficacy. Herein, a novel hyperbranched polyphosphoester (hbPPE) containing numerous acetal bonds (S-hbPPE/Ce6) was explored as a chlorin e6 (Ce6) nanocarrier for PDT. S-hbPPE/Ce6 with a branched topological structure efficiently encapsulated Ce6 and then significantly enhanced its internalization by tumor cells. Subsequently, the endo-/lysosomal acid microenvironment rapidly cleaved the acetal linkage of S-hbPPE and destroyed the nanostructure of S-hbPPE/Ce6, resulting in increased Ce6 release and obviously elevated the intracellular ROS generation under illumination. Therefore, treatment with S-hbPPE/Ce6 noticeably enhanced the PDT therapeutic efficacy, indicating that such a pH-sensitive hbPPE nanocarrier has great potential to improve the PDT therapeutic efficacy for cancer therapy.

Cascade-amplifying synergistic effects of chemo-photodynamic therapy using ROS-responsive polymeric nanocarriers

The simple integration of chemotherapeutic drugs and photosensitizers (PSs) into the same nanocarriers only achieves a combination of chemo-photodynamic therapy but may not confer synergistic effects. The boosted intracellular release of chemotherapeutic drugs during the photodynamic therapy (PDT) process is necessary to achieve a cascade of amplified synergistic therapeutic effects of chemo-photodynamic therapy. Methods: In this study, we explored an innovative hyperbranched polyphosphate (RHPPE) containing a singlet oxygen (SO)-labile crosslinker to boost drug release during the PDT process. The photosensitizer chlorin e6 (Ce6) and doxorubicin (DOX) were simultaneously loaded into RHPPE nanoparticles (denoted as ^SOHNP_Ce6/DOX). The therapeutic efficacy of ^SOHNP_Ce6/DOX against drug-resistant cancer was evaluated in vitro and in vivo. Results: Under 660-nm light irradiation, ^SOHNP_Ce6/DOX can produce SO, which not only induces PDT against cancer but also cleaves the thioketal linkers to destroy the nanoparticles. Subsequently, boosted DOX release can be achieved, activating a chemotherapy cascade to synergistically destroy the remaining tumor cells after the initial round of PDT. Furthermore, ^SOHNP_Ce6/DOX also efficiently detected the tumor area by photoacoustic/magnetic resonance bimodal imaging. Under the guidance of bimodal imaging, the laser beam was precisely focused on the tumor areas, and subsequently, ^SOHNP_Ce6/DOX realized a cascade of amplified synergistic chemo-photodynamic therapeutic effects. High antitumor efficacy was achieved even in a drug-resistant tumor model. Conclusion: The designed ^SOHNP_Ce6/DOX with great biocompatibility is promising for use as a co-delivery carrier for combined chemo-photodynamic therapy, providing an alternative avenue to achieve a cascade of amplified synergistic effects of chemo-photodynamic therapy for cancer treatment.

pH-responsive gold nanoclusters-based nanoprobes for lung cancer targeted near-infrared fluorescence imaging and chemo-photodynamic therapy

Nanoparticle-based drug delivery systems have drawn a great deal of attention for their opportunities to improve cancer treatments over intrinsic limits of conventional cancer therapies. Herein, we developed the polypeptide-modified gold nanoclusters (GNCs)-based nanoprobes for tumor-targeted near-infrared fluorescence imaging and chemo-photodynamic therapy. The nanoprobes comprise of tetra-functional components: i) polyethylene glycol (PEG) shell for long blood circulation and better biocompatibility; ii) MMP2 polypeptide (CPLGVRGRGDS) for tumor targeting; iii) cis-aconitic anhydride-modified doxorubicin (CAD) for pH-sensitive drug release; iv) photosensitizer chlorin e6 (Ce6) for photodynamic therapy and fluorescence imaging. The in vitro results demonstrated that the as-synthesized nanoprobes could be efficiently internalized into A549 cells and then significantly enhance the mortality of cancer cells compared with free Ce6 and doxorubicin. For in vivo tests, the nanoprobes showed excellent tumor targeting ability, long blood circulation time, and could remarkably inhibit the growth of tumor. Our results will help to advance the design of combination strategies to enhance the efficacy of imaging-guided cancer therapy.

STATEMENT OF SIGNIFICANCE

The as-prepared CDGM NPs could accumulate into the tumor tissue with the enhanced permeability and retention (EPR) effect as well as the active tumor targeting ability from the MMP2 polypeptides. With the acid-sensitive linker, the doxorubicin (DOX) would be released from the synthesized nanoparticles after exposing to the acid tumor microenvironment. The CDGM NPs exhibit excellent tumor targeting ability and could remarkably suppress the growth of tumor compared with free Ce6 and DOX.

PEG conjugated BODIPY-Br2 as macro-photosensitizer for efficient imaging-guided photodynamic therapy

PEG-BDP macro-photosensitizer was synthesized which showed imaging-guided photodynamic therapy.

Fluorescence guided photothermal/photodynamic ablation of tumours using pH-responsive chlorin e6-conjugated gold nanorods

Photothermal/photodynamic therapies (PTT/PDT) have been widely accepted as non-invasive therapeutic modalities to erase tumours. However, both therapies face the problem of precisely locating tumours and reducing their side effects. Herein, chlorin e6 conjugated gold nanorod, (Ce6-PEG-AuNR), a type of gold nanorod-photosensitizer conjugate, is designed as a kind of nano-therapeutic agent to simultaneously realize combined PTT/PDT. Compared to free Ce6, the fluorescence of Ce6 adhered to the conjugate is effectively quenched by the longitudinal surface plasmon resonance (LSPR) of in the Ce6-PEG-AuNR. However, the specific fluorescence of Ce6 can be recovered in tumour tissue when Ce6 is separated from the conjugate owing to the cleavage of hydrazone bond between Ce6 and PEG caused by intracellular acidic conditions in tumour tissue. Based on this effect, we can precisely locate tumours and further kill cancer cells by combined PTT/PDT. In addition, the combined therapy (PTT/PDT) function is more efficient in cancer treatment than that of PTT or PDT alone. Therefore, Ce6-PEG-AuNR can serve as a promising dual-modal phototherapeutic agent as well as a tumour-sensitive fluorescent probe to diagnose and treat cancer.

Polymeric mixed micelles loaded mitoxantrone for overcoming multidrug resistance in breast cancer via photodynamic therapy

Mitoxantrone (MIT) is an anticancer agent with photosensitive properties that is commonly used in various cancers. Multidrug resistance (MDR) effect has been an obstacle to using MIT for cancer therapy. Photochemical internalization, on account of photodynamic therapy, has been applied to improve the therapeutic effect of cancers with MDR effect. In this study, an MIT-poly(ε-caprolactone)-pluronic F68-poly(ε-caprolactone)/poly(d,l-lactide-co-glycolide)–poly(ethylene glycol)–poly(d,l-lactide-co-glycolide) (MIT-PFP/PPP) mixed micelles system was applied to reverse the effect of MDR in MCF-7/ADR cells via photochemical reaction when exposed to near-infrared light. MIT-PFP/PPP mixed micelles showed effective interaction with near-infrared light at the wavelength of 660 nm and exerted great cytotoxicity in MCF-7/ADR cells with irradiation. Furthermore, MIT-PFP/PPP mixed micelles could improve reactive oxygen species (ROS) levels, decrease P-glycoprotein activity, and increase the cellular uptake of drugs with improved intracellular drug concentrations, which induced cell apoptosis in MCF-7/ADR cells under irradiation, despite MDR effect, as indicated by the increased level of cleaved poly ADP-ribose polymerase. These findings suggested that MIT-PFP/PPP mixed micelles may become a promising strategy to effectively reverse the MDR effect via photodynamic therapy in breast cancer.

Tumor acidity-activatable TAT targeted nanomedicine for enlarged fluorescence/magnetic resonance imaging-guided photodynamic therapy

Nanoparticles simultaneously integrated the photosensitizers and diagnostic agents represent an emerging approach for imaging-guided photodynamic therapy (PDT). However, the diagnostic sensitivity and therapeutic efficacy of nanoparticles as well as the heterogeneity of tumors pose tremendous challenges for clinical imaging-guided PDT treatment. Herein, a polymeric nanoparticle with tumor acidity (pH_e)-activatable TAT targeting ligand that encapsulates the photosensitizer chlorin e6 (Ce6) and chelates contrast agent Gd³⁺ is successfully developed for fluorescence/magnetic resonance (MR) dual-model imaging-guided precision PDT. We show clear evidence that the resulting nanoparticle ^DATAT-NP [its TAT lysine residues' amines was modified by 2,3-dimethylmaleic anhydride (DA)] efficiently avoids the rapid clearance by reticuloendothelial system (RES) by masking of the TAT peptide, resulting in the significantly prolonged circulation time in the blood. Once accumulating in the tumor tissues, ^DATAT-NP is reactivated by tumor acidity to promote cellular uptake, resulting in enlarged fluorescence/MR imaging signal intensity and elevated in vivo PDT therapeutic effect. This concept provides new avenues to design tumor acidity-activatable targeted nanoparticles for imaging-guided cancer therapy.

Design of Tumor Acidity-Responsive Sheddable Nanoparticles for Fluorescence/Magnetic Resonance Imaging-Guided Photodynamic Therapy

Imaging-guided cancer therapy, which integrates diagnostic and therapeutic functionalities into a single system, holds great promise to enhance the accuracy of diagnosis and improve the efficacy of therapy. Specifically, for photodynamic therapy (PDT), it is highly desirable to precisely focus laser light onto the tumor areas to generate reactive oxygen species (ROS) that are cytotoxic tumor cells and avoid light-associated side effects. Herein, a distinct three-layer nanostructured particle with tumor acidity-responsiveness (S-NP) that encapsulates the photosensitizer chlorin e6 (Ce6) and chelates Gd³⁺ is successfully developed for fluorescence/magnetic resonance (MR) dual-model imaging-guided precision PDT. We show clear evidence that the outer PEG layer significantly prolongs circulation time, and the inner poly(ε-caprolactone) (PCL) core can physically encapsulate Ce6. More interestingly, the middle layer of the S-NP, acting as a molecular fence to keep Ce6 in the circulation system, was dismantled by the slightly acidic tumor microenvironment. Afterwards, the PEG shell is deshielded from the S-NP at the tumor tissue, resulting in improved cell uptake, enlarged MR signal intensity, rapid release of Ce6 within tumor cells, and elevated PDT efficacy. Our results suggest that tumor-acidity-responsive nanoparticles with fine design could serve as a theranostic platform with great potential in imaging-guided PDT treatment of cancer.

Water-Insoluble Photosensitizer Nanocolloids Stabilized by Supramolecular Interfacial Assembly towards Photodynamic Therapy

Nanoengineering of hydrophobic photosensitizers (PSs) is a promising approach for improved tumor delivery and enhanced photodynamic therapy (PDT) efficiency. A variety of delivery carriers have been developed for tumor delivery of PSs through the enhanced permeation and retention (EPR) effect. However, a high-performance PS delivery system with minimum use of carrier materials with excellent biocompatibility is highly appreciated. In this work, we utilized the spatiotemporal interfacial adhesion and assembly of supramolecular coordination to achieve the nanoengineering of water-insoluble photosensitizer Chlorin e6 (Ce6). The hydrophobic Ce6 nanoparticles are well stabilized in a aqueous medium by the interfacially-assembled film due to the coordination polymerization of tannic acid (TA) and ferric iron (Fe(III)). The resulting Ce6@TA-Fe(III) complex nanoparticles (referenced as Ce6@TA-Fe(III) NPs) significantly improves the drug loading content (~65%) and have an average size of 60 nm. The Ce6@TA-Fe(III) NPs are almost non-emissive as the aggregated states, but they can light up after intracellular internalization, which thus realizes low dark toxicity and excellent phototoxicity under laser irradiation. The Ce6@TA-Fe(III) NPs prolong blood circulation, promote tumor-selective accumulation of PSs, and enhanced antitumor efficacy in comparison to the free-carrier Ce6 in vivo evaluation.

Self-assembled DNA nanowires as quantitative dual-drug nanocarriers for antitumor chemophotodynamic combination therapy

Self-assembled DNA nanowires were fabricated through a supersandwich hybridization reaction and co-loaded with a photosensitizer chlorin e6 (Ce6) and a chemotherapeutic drug doxorubicin (DOX) for antitumor chemophotodynamic combination therapy.

V, Nalam MR, Sunkara MV. Chlorin e6 loaded lactoferrin nanoparticles for enhanced photodynamic therapy

The LeN NPs of Lf and Ce6 enhanced the intracellular delivery of the PS improving photo-induced cell death compared to free PS.

Polyphosphoesters: New Trends in Synthesis and Drug Delivery Applications

Polymers with repeating phosphoester linkages in the backbone are biodegradable materials that emerge as a promising class of novel biomaterials, especially in the field of drug delivery systems. In contrast to aliphatic polyesters, the pentavalency of the phosphorus atom offers a large diversity of structures and as a consequence a wide range of properties for these materials. In this paper, it is focused on the synthesis of well-defined polyphosphoesters (PPEs) by organocatalyzed ring-opening polymerization, improving the functionalities by combination with click reactions, degradation of functional PPEs and their cytotoxicity, and inputs for applications in drug delivery.

Fullerene/photosensitizer nanovesicles as highly efficient and clearable phototheranostics with enhanced tumor accumulation for cancer therapy

A novel phototheranostic platform based on tri-malonate derivative of fullerene C70 (TFC70)/photosensitizer (Chlorin e6, Ce6) nanovesicles (FCNVs) has been developed for effective tumor imaging and treatment. The FCNVs were prepared from amphiphilic TFC70-oligo ethylene glycol -Ce6 molecules. The developed FCNVs possessed the following advantages: (i) high loading efficiency of Ce6 (up to ∼57 wt%); (ii) efficient absorption in near-infrared light region; (iii) enhanced cellular uptake efficiency of Ce6 in vitro and in vivo; (iv) good biocompatibility and total clearance out from the body. These unique properties suggest that the as-prepared FCNVs could be applied as an ideal theranostic agent for simultaneous imaging and photodynamic therapy of tumor. This finding may provide a good solution to highly efficient phototheranostic applications based on fullerene derivatives fabricated nanostructures.

MMP2-Targeting and Redox-Responsive PEGylated Chlorin e6 Nanoparticles for Cancer Near-Infrared Imaging and Photodynamic Therapy

A unique matrix metalloproteinase 2-targeted photosensitizer delivery platform was developed in this study for tumor-targeting imaging and photodynamic therapy. The model photosensitizer therapeutic agent chlorin e6 (Ce6) was first covalently conjugated with matrix metalloproteinase 2-cleavable polypeptide and then modified with polyethylene glycol via a redox-responsive cleavable disulfide linker. The resultant matrix metalloproteinase 2-cleavable polypeptide modified PEGylated Ce6 (PEG-SS-Ce6-MMP2) nanoparticles, which formed via self-assembly, were observed to be monodisperse and significantly stable in aqueous solution. In addition, owing to their cellular redox-responsiveness at the cleavable disulfide linker, the PEG-SS-Ce6-MMP2 nanoparticles were able to release Ce6 rapidly. Despite displaying enhanced intracellular internalization, the synthesized PEG-SS-Ce6-MMP2 nanoparticles did not compromise their phototoxic effects toward A549 cancer cells when compared with free Ce6 and PEGylated Ce6 nanoparticles. In vivo experiments further revealed that, in contrast with the free Ce6 or with the PEGylated Ce6 nanoparticles, the PEG-SS-Ce6-MMP2 nanoparticles showed a remarkable increase in tumor-targeting ability and a significantly improved photodynamic therapeutic efficiency in A549 tumor-bearing mice. These results suggest that the PEG-SS-Ce6-MMP2 nanoparticles hold great potential for tumor-targeting imaging and photodynamic therapy.

PEGylated hyperbranched polyphosphoester based nanocarriers for redox-responsive delivery of doxorubicin

A PEGylated hyperbranched polyphosphoester containing multiple disulfide bonds (ss-hbPPE) was used and evaluated as a redox-responsive delivery system.

Photosensitizer-Loaded Branched Polyethylenimine-PEGylated Ceria Nanoparticles for Imaging-Guided Synchronous Photochemotherapy

A multifunctional theranostic platform based on photosensitizer (chlorin e6, Ce6)-loaded branched polyethylenimine-PEGylated ceria nanoparticles (PPCNPs-Ce6) was created for the development of effective cancer treatments involving the use of imaging-guided synchronous photochemotherapy. PPCNPs-Ce6 with high Ce6 photosensitizer loading (Ce6: cerium ∼40 wt %) significantly enhanced the delivery of Ce6 into cells and its accumulation in lysosomes, remarkably improving photodynamic therapeutic (PDT) efficacy levels compared to those in the administration of free Ce6 at ultralow drug doses (∼200 nM). Interestingly, PPCNPs-Ce6 efficiently induced HeLa cell death even at low concentrations (∼10 μM) without the use of laser irradiation and exhibit chemocytotoxicity. Inductively coupled plasma mass spectrometry (ICP-MS) and biology transmission electron microscopy (Bio-TEM) analyses demonstrated that ceria nanoparticles enter cells abundantly and accumulate in lysosomes or large vesicles. We then evaluated the effects of the different materials on lysosomal integrity and function, which revealed that PPCNPs-Ce6 catastrophically impaired lysosomal function compared to results with PPCNPs and Ce6. Studies of apoptosis revealed greater induction of apoptosis by PPCNPs-Ce6 treatment. This multifunctional nanocarrier also exhibited a high degree of solubility and stability in aqueous solutions, suggesting its applicability for extensive biomedical application.