Chlorin E6 Research Articles

Carrier free nanomedicine to reverse anti-apoptosis and elevate endoplasmic reticulum stress for enhanced photodynamic therapy

As a first studied and generally accepted programmed cell death regulator, Bcl-2 has been identified to overexpress in many types of cancer promoting tumor proliferation and progression. Herein, inspired by drug self-delivery systems, a self-assembled nanomedicine (designated as GosCe) was designed based on the hydrophobic interaction between chlorin e6 (Ce6) and gossypol (Gos). Without extra carriers, GosCe exhibited high drug loading rates, favorable size distribution, and a long-term stability at aqueous phase. More importantly, GosCe could be internalized by tumor cells more effectively than free Ce6, which brought about its multiple toxicity. Upon intravenous injection, GosCe preferred to accumulate in tumor site through enhanced permeability and retention (EPR) effect. After cellular internalization, Gos contributed to increasing the lethality of Ce6-guided photodynamic therapy (PDT) by down-regulating Bcl-2 protein expression and inducing endoplasmic reticulum (ER) stress. Both in vitro and in vivo investigations indicated that the Gos-assisted PDT greatly inhibit cell proliferation and tumor growth. This study might shed light on developing carrier free nanomedicine for PDT-based synergistic tumor therapy. Statement of SignificanceMetabolic abnormalities of tumor cells create defensive microenvironments which induce a therapeutic resistance against photodynamic therapy (PDT). Among which, the upregulated B-cell lymphoma (Bcl-2) in tumors could inhibit the PDT-induced cell apoptosis. In this work, a self-delivery nanomedicine (GosCe) was developed based on a Bcl-2 inhibitor and photosensitizer through intermolecular interactions, which had favorable size distribution, high drug contents and improved drug delivery efficiency. Importantly, GosCe increased the PDT efficacy by Bcl-2 inhibition and endoplasmic reticulum stress elevation. Thus, GosCe greatly inhibited the tumor growth while caused a reduced side effect in vivo. This carrier free nanomedicine with tumor microenvironment regulation would advance the development of photodynamic nanoplatform in tumor treatment.

The role of autophagy in the treatment of colon cancer by chlorin e6 photodynamic therapy combined with oxaliplatin

BackgroundPhotodynamic therapy is a tumour treatment method. Its mechanism mainly induces apoptosis, autophagy, and other ways to cause cell death. Therefore, this study aims to evaluate the therapeutic effect of chlorine e6 photodynamic therapy (Ce6-PDT) combined with oxaliplatin (L-OHP) in colon cancer and to investigate the role of autophagy in L-OHP treatment and Ce6-PDT combined with L-OHP in colon cancer. MethodsCCK-8 assay, Scratch wound healing assay, and Western Blot (WB) were used to identify drug-resistant colon cancer cell line SW620/L-OHP. Annexin V/FITC assay, laser confocal double immunofluorescence staining method and WB were employed to investigate the apoptosis and autophagy changes in Ce6-PDT combined with L-OHP. ResultsDrug resistance cells SW620/L-OHP were developed under the continuous multi-generation of L-OHP treatment, and the expression of ATP-binding cassette subfamily B member 1 (ABCB1) and ATG5 proteins were increased. The results of immunofluorescence showed that LC3B accumulated in SW620 cells and SW620/L-OHP cells under the treatment of L-OHP. The WB results indicated that LC3B and ATG5 protein expression was increasing in SW620 cells and SW620/L-OHP cells. Inhibition of L-OHP-induced autophagy reduces SW620 cells and SW620/L-OHP cells’ viability while increasing apoptosis and the Pro Caspase-3 protein expression. The combination of Ce6-PDT and L-OHP decreased the cell viability, the cell migration ability, the Bcl-2 protein expression, and increased the apoptosis rate, Pro Caspase-3 protein expression in SW620 cells. ConclusionsL-OHP can cause SW620 cells drug resistance. Autophagy plays a protective role in the L-OHP treatment of SW620 cells and SW620/L-OHP cells, and inhibition of autophagy can increase the efficacy of L-OHP. Ce6-PDT combined with L-OHP can further improve the tumor's therapeutic effect, and autophagy inhibition can improve the efficacy of combined therapy.

Construction of multifunctional mesoporous silicon nano-drug delivery system and study of dual sensitization of chemo-photodynamic therapy in vitro and in vivo

This study was conducted to construct a multifunctional nanodrug delivery system (NDDS) to deplete glutathione (GSH) in tumor cells and amplify oxidative stress, enhancing the synergistic effect of chemotherapy and photodynamic therapy (PDT). l-Buthionine-sulfoximine (BSO) and chlorin e6 (Ce6) were loaded into mesoporous silicon nanoparticles (MSN), and then MSN were modified with oxidized hyaluronic acid (OHA) as a pore-blocking agent. Cisplatin (Pt(II)) was further loaded by a coordination reaction with carboxyl groups in OHA to yield a multifunctional NDDS (denoted as MSN@OHA-Ce6/BSO/Pt). The physicochemical properties and antitumor activity of the prepared nanoparticles were characterized in detail. In vitro and in vivo experiments demonstrated that OHA was shed from MSN@OHA-Ce6/BSO/Pt under acidic conditions in tumors, resulting in the release of free BSO, Ce6, and Pt(II). The released BSO could reduce intracellular GSH expression by 48.8 %, effectively enhancing the PDT effect of Ce6 and the chemotherapy effect of Pt(II). Finally, the tumor inhibitory rate (vs saline) reached 73.8 % ± 2.5 % for MSN@OHA-Ce6/BSO/Pt in A549/DDP tumor-bearing nude mice. Therefore, the multifunctional NDDS significantly enhanced the synergistic effect of PDT and chemotherapy.

Near-infrared light and redox dual-activatable nanosystems for synergistically cascaded cancer phototherapy with reduced skin photosensitization

Currently, activatable photodynamic therapy (PDT) that is precisely regulated by endogenous or exogenous stimuli to selectively produce cytotoxic reactive oxygen species at the tumor site is urgently in demand. Herein, we fabricated a dual-activatable PDT nanosystem regulated by the redox tumor microenvironment and near-infrared (NIR) light-induced photothermal therapy (PTT). In this study, photosensitizer chlorin e6 (Ce6) was conjugated to hyaluronic acid (HA) via a diselenide bond to form an amphiphilic polymer (HSeC) for loading PTT agent IR780 to produce HSeC/IR nanoparticles (NPs). The photoactivity of Ce6 for PDT was “double-locked” by the aggregation-caused quenching (ACQ) effect and the fluorescence resonance energy transfer (FRET) from Ce6 to IR780 during blood circulation. After selective accumulation into tumors, HSeC/IR NPs were subsequently dissociated due to the “double-key”, which included diselenide bond dissociation under high redox conditions and IR780 degradation upon NIR laser irradiation, resulting in recovering Ce6. In vitro studies indicated that Ce6 photoactivity in HSeC/IR NPs was significantly suppressed when compared with free Ce6 or in HSeC NPs. Moreover, BALB/c mice treated with HSeC/IR NPs displayed distinctly alleviated skin damage during PDT. Synergetic cascaded PTT-PDT with superior tumor suppression was observed in SCC7 tumor-bearing mice. Therefore, the study findings could provide a promising treatment strategy for PTT-facilitated PDT with high antitumor efficacies and reduced skin phototoxicity levels.

Pt/Ag‐PEG‐Ce6 Nanosystem with Enhanced Near‐Infrared Absorption and Peroxidase‐Like Activity for Synergistic Photodynamic/Photothermal Therapy

AbstractNoble metals and their alloy‐based nanomaterials are widely used in biomedicine, especially in the fields of photodynamic therapy (PDT) and photothermal therapy (PTT) on tumors, due to their remarkable physicochemical properties. Nonetheless, novel doping strategies with unexpected efficacies are still challenging and formidable. Herein, a photosensitizer‐alloy nanosystem is designed for highly efficient PDT and PTT. Specifically, the optimized Pt/Ag alloy nanoparticles are facilely synthesized in one step at room temperature and are simultaneously endowed with enhanced peroxidase‐like activity and photothermal conversion, and further activated cytotoxic singlet oxygen (1O2) productivity after covalent functionalization of chlorin e6 (Ce6). A small amount of Ag doping can kill two birds with one stone by simultaneously enhancing the synergistic PDT and PTT potential of Pt/Ag‐PEG‐Ce6 nanoparticles. Both in vitro and in vivo experimental results indicate that the significant temperature increase triggered by 808 nm laser and a large amount of toxic 1O2 excited by 671 nm laser synergistically and strongly kill tumor cells. Therefore, through proper doping and improved physicochemical properties, this nanosystem achieves effective PDT and PTT of tumors and also inspires the advanced design of noble metal‐based nanomedicine.

Targeted Delivery of Chemo-Sonodynamic Therapy via Brain Targeting, Glutathione-Consumable Polymeric Nanoparticles for Effective Brain Cancer Treatment.

Glioblastoma (GBM) is the most aggressive tumor of the central nervous system and remains universally lethal due to lack of effective treatment options and their inefficient delivery to the brain. Here the development of multifunctional polymeric nanoparticles (NPs) for effective treatment of GBM is reported. The NPs are synthesized using a novel glutathione (GSH)‐reactive poly (2,2″‐thiodiethylene 3,3″‐dithiodipropionate) (PTD) polymer and engineered for brain penetration through neutrophil elastase‐triggered shrinkability, iRGD‐mediated targeted delivery, and lexiscan‐induced autocatalysis. It is found that the resulting lexiscan‐loaded, iRGD‐conjugated, shrinkable PTD NPs, or LiPTD NPs, efficiently penetrate brain tumors with high specificity after intravenous administration. Furthermore, it is demonstrated that LiPTD NPs are capable of efficient encapsulation and delivery of chemotherapy doxorubicin and sonosensitizer chlorin e6 to achieve combined chemotherapy and sonodynamic therapy (SDT). It is demonstrated that the capability of GSH depletion of LiPTD NPs further augments the tumor cell killing effect triggered by SDT. As a result, treatment with LiPTD NPs effectively inhibits tumor growth and prolongs the survival of tumor‐bearing mice. This study may suggest a potential new approach for effective GBM treatment.

Photoswitchable semiconducting polymer dots with photosensitizer molecule and photochromic molecule loading for photodynamic cancer therapy

Photodynamic therapy (PDT) is a new and rapidly developing treatment modality for clinical cancer therapy. Semiconductor polymer dots (Pdots) doped with photosensitizers have been successfully applied to PDT, and have made progress in the field of tumor therapy. However, the problems of severe photosensitivity and limited tissue penetration depth are needed to be solved during the implementation process of PDT. Here we developed the Pdots doped with photosensitizer molecule Chlorin e6 (Ce6) and photochromic molecule 1,2-bis(2,4-dimethyl-5-phenyl-3-thiophene)-3,3,4,5-hexafluoro-1-cyclopentene (BTE) to construct a photoswitchable nanoplatform for PDT. The Ce6-BTE-doped Pdots were in the green region, and the tissue penetration depth was increased compared with most Pdots in the blue region. The reversible conversion of BTE under different light irradiation was utilized to regulate the photodynamic effect and solve the problem of photosensitivity. The prepared Ce6-BTE-doped Pdots had small size, excellent optical property, efficient ROS generation and good photoswitchable ability. The cellular uptake, cytotoxicity, and photodynamic effect of the Pdots were detected in human colon tumor cells. The experiments in vitro indicated that Ce6-BTE-doped Pdots could exert excellent photodynamic effect in ON state and reduce photosensitivity in OFF state. These results demonstrated that this nanoplatform holds the potential to be used in clinical PDT.

Co‐delivery of Cisplatin and Chlorin e6 by Poly(phosphotyrosine) for Synergistic Chemotherapy and Photodynamic Therapy

Comprehensive SummaryNanoscale drug delivery systems (NDDSs) have emerged as promising carriers for combinational therapy by co‐delivery of multiple drugs and modalities. However, most co‐delivery systems require the use of complicated materials and formulations. Herein, we report the single use of a polymeric material, namely mPEG‐block‐poly(phosphotyrosine) (mPEG‐b‐PpY), as a multi‐functional carrier for the facile fabrication of NDDS Pt/Ce6@mPEG‐b‐PpY (PtCeNP) for the co‐delivery of cisplatin and photosensitizer chlorin e6 (Ce6) via phosphato‐platinum coordination and π‐π stacking, respectively. PtCeNP improves the solubility, cellular uptake, and bioavailability of both parental drugs, and showed strong synergistic antitumor efficacy both in vitro and in vivo through combined chemo‐photodynamic therapy. Our results indicate that PpY is a biocompatible, multifunctional, and promising carrier material suitable for a variety of drugs and may simplify the design for co‐delivery systems.

Targeted chemo-photodynamic therapy toward esophageal cancer by GSH-sensitive theranostic nanoplatform

As the sixth leading cause of cancer death, esophageal cancer is threatening the life of people worldwide. Traditional treatments, such as surgery, chemotherapy, radiotherapy, are facing always augmented challenges including invasion, multidrug resistance (MDR), off-target toxicity. Chemo & Photodynamic synergistic therapy represents one promising strategy for improved treatment efficiency. But it is still hindered by the lack of tumor targeting, deleterious side effects, and unfavorable microenvironment for photodynamic therapy (PDT). To overcome those obstacles, one theranostic nano-assambly drug, GCDs-Ce6/Pt-EGF, was designed and fabricated. Green fluorescence carbon dots (GCDs) with the excellent optical properties, modifiability and low toxicity were prepared as drug carrier. Epidermal growth factor (EGF) was conjugated to the nano-assembly to realize tumor specific targeting. Chlorin e6 (Ce6) in the presence of laser irradiation achieved PDT by generating proapoptosis reactive oxygen species (ROS). Moreover, Ce6 incorporated into GCDs endowed the nano-assambly imaging ability and facilitate image-guided therapy. Pt(IV), cisplatin prodrug, in the nano-assambly depleted the glutathione (GSH) of tumor microenvironment when it was reduced to cytotoxicity Pt(II). Compared with single treatment, GCDs-Ce6/Pt-EGF exhibited enhanced tumor cell killing capacity and better biosafety in vitro and in vivo, especially for EGFR bearing tumor. It paved ways for developing novel theranostic agent to be potentially applied in clinic.

NIR-Triggered Generation of Reactive Oxygen Species and Photodynamic Therapy Based on Mesoporous Silica-Coated LiYF4 Upconverting Nanoparticles.

To date, the increase in reactive oxygen species (ROS) production for effectual photodynamic therapy (PDT) treatment still remains challenging. In this study, a facile and effective approach is utilized to coat mesoporous silica (mSiO2) shell on the ligand-free upconversion nanoparticles (UCNPs) based on the LiYF4 host material. Two kinds of mesoporous silica-coated UCNPs (UCNP@mSiO2) that display green emission (doped with Ho3+) and red emission (doped with Er3+), respectively, were successfully synthesized and well characterized. Three photosensitizers (PSs), merocyanine 540 (MC 540), rose bengal (RB), and chlorin e6 (Ce6), with the function of absorption of green or red emission, were selected and loaded into the mSiO2 shell of both UCNP@mSiO2 nanomaterials. A comprehensive study for the three UCNP@mSiO2/PS donor/acceptor pairs was performed to investigate the efficacy of fluorescence resonance energy transfer (FRET), ROS generation, and in vitro PDT using a MCF-7 cell line. ROS generation detection showed that as compared to the oleate-capped and ligand-free UCNP/PS pairs, the UCNP@mSiO2/PS nanocarrier system demonstrated more pronounced ROS generation due to the UCNP@mSiO2 nanoparticles in close vicinity to PS molecules and a higher loading capacity of the photosensitizer. As a result, the three LiYF4 UCNP@mSiO2/PS nanoplatforms displayed more prominent therapeutic efficacies in PDT by using in vitro cytotoxicity tests.

PARP inhibitors diminish DNA damage repair for the enhancement of tumor photodynamic therapy

Pancreatic cancer is a lethal malignancy and only around 4% of patients will live 5 years post-diagnosis. Photodynamic therapy (PDT) is a promising strategy for treating malignant tumors because of its high selectivity. Through the colocalization of light, oxygen and photosensitizer, a large number of reactive oxygen species (ROS) are generated under excitation at a specific wavelength of a laser, which can induce DNA damage and destroy cancer cells. However, the repair mechanism of cell will repair part of the damaged DNA, which could reduce the efficiency of PDT. The poly (ADP-Ribose) polymerase (PARP) plays a wide and multifaceted role in the cellular response to DNA damage, with growing evidence for participation in multiple pathways of DNA damage repair and genome maintenance. Cells require PARP to resolve single-strand DNA breaks (SSBs) induced by chemotherapy agents. Its inhibition is thought to result in the accumulation of damage in DNA, which may eventually lead to cell death. The combination therapy of PDT and PARP inhibitors may benefit patients. In this study, we design and synthesize a zeolitic imidazolate framework-8 (ZIF-8) to co-deliver DNA damaging agent Chlorin e6 (Ce6) and PARP inhibitor Olaparib (Ola). Ce6 and Ola demonstrate strong synergistic actions, providing a novel approach for the treatment of pancreatic cancer.

Platinum-based nanocomposites loaded with MTH1 inhibitor amplify oxidative damage for cancer therapy

Photodynamic therapy (PDT) is a promising therapeutic strategy for tumor ablation by generating highly toxic reactive oxygen species (ROS) to damage DNA and other biomacromolecules. However, the local hypoxic microenvironment of the tumor and the presence of ROS-defensing system, such as the mobilization of mutt homolog 1 (MTH1) to sanitize ROS-oxidized nucleotide pool, severely limit the efficiency of PDT. Therefore, a novel tumor ablation strategy was developed that not only focused on the enhancement of ROS generation but also weakened the ROS-defensing system by inhibiting MTH1 enzyme activity. In our work, a simple one-step reduction approach was applied to enable platinum nanoparticles (Pt NPs) with catalase activity to grow in situ in the nanochannels of mesoporous silica nanoparticles (MSNs). After physical encapsulation of photosensitizer chlorin e6 (Ce6) and MTH1 inhibitor TH588, the drug loading nanoplatform was modified with an arginine-glycine-aspartic acid (RGD) functionalized liposome shell, resulting in the fabrication of amplified oxidative damage nanoplatform MSN-Pt@Ce6/TH588 @Liposome-RGD (MPCT@Li-R). The prepared MPCT@Li-R NPs could continuously catalyze the decomposition of hydrogen peroxide (H2O2) into oxygen (O2) in tumor, thus promoting the generation of singlet oxygen during PDT process for improved oxidative damage of bases. Simultaneously, acid responsive released TH588 hindered MTH1-mediated scavenging of oxidative bases, further aggravating DNA oxidative damage. Consequently, this cascade therapy strategy exhibited excellent tumor suppression efficiency both in vitro and in vivo.

Penetration and photodynamic ablation of drug-resistant biofilm by cationic Iron oxide nanoparticles.

As we step into the post-antibiotic era, the accelerated emergence of antibiotic-resistant pathogenic bacteria poses an increasingly serious threat to public health. The formation of antibiotic-resistant biofilms further challenges currently available drugs and treatment options, calling for novel strategies for effective ablation of such biofilm with minimal concern on safety and development of resistance. Herein, we report a novel type of photodynamic nanoagent, composed of chlorin e6 (Ce6)-loaded water-soluble chitosan-coated iron oxide nanoparticles (named Ce6@WCS-IONP), for drug-resistant bacteria killing and biofilm eradication. The fabricated Ce6@WCS-IONP has negligible toxicity to mammalian cells and exhibited equivalent singlet oxygen generation capacity to free Ce6; however, its association with methicillin-resistant Staphylococcus aureus (MRSA) was greatly enhanced, as evidenced by flow cytometry analysis and transmission electron microscope. In vitro studies verified that Ce6@WCS-IONP has superior photodynamic bactericidal effect against planktonic MRSA. Furthermore, with the aid of the cationic nature and small size, Ce6@WCS-IONP could effectively penetrate into MRSA biofilm, revealed by 3D fluorescence imaging. Both biomass analysis and viable bacteria counting demonstrated that Ce6@WCS-IONP showed potent biofilm ablation efficacy, averagely 7.1 log unit lower than that in free Ce6 group upon identical light irradiation. In addition, local treatment of MRSA-infected mice with Ce6@WCS-IONP plus light irradiation resulted in significant antibacterial and wound healing effect, accompanied by good biocompatibility in vivo. Collectively, photosensitizer-loaded cationic IONP with effective biofilm penetration and photodynamic eradication potential might be a promising nano platform in fighting against antibiotic-resistant microbial pathogen and biofilm.

Evaluation of photosensitizer-containing superhydrophobic surfaces for the antibacterial treatment of periodontal biofilms.

Antimicrobial photodynamic therapy (aPDT) is a promising approach to control biofilms involved in periodontal diseases. However, certain challenges, such as staining of teeth, preferential interaction of photosensitizer (PS) with Gram-positive versus Gram-negative bacteria, and insufficient oxygen in hypoxic periodontal pockets have presented barriers to its use in the clinic. To overcome these challenges, a novel superhydrophobic (SH) film that generates airborne singlet oxygen has been developed. The SH-aPDT approach isolates the PS onto a topologically rough solid SH film on which channels allow air to diffuse to the PS surface, thus ensuring sufficient oxygen supply. Upon illumination, gas phase singlet oxygen (1O2) is produced and diffuses from the SH surface to the underlying biofilm. The killing efficacy was assessed as a function of transmitted fluence (17.9-89.5J/cm2) and chorin e6 loading (96-1110nmol/cm2) by counting of colony forming units, biofilm metabolism by XTT and confocal microscopy. The decrease in viability of both Gram-positive and Gram-negative bacteria in a multi-species biofilm was found to be linearly dependent on the fluence as well as the loading of the PS up to 71.6J/cm2 when 1110 nmols/cm2 of chlorin e6 was used. A>4.6 log bacterial reduction was observed under these conditions (p<0.05). This novel SH-aPDT approach shows promise as an effective method to disinfect multi-species bacterial biofilms associated with periodontal disease and will be evaluated in animal models in future studies.

Tumor homing-penetrating and nanoenzyme-augmented 2D phototheranostics against hypoxic solid tumors

Tumor microenvironment (TME)-oriented nanomedicine emerges as an efficient routine to greatly improve the efficiency of cancer treatment. The typical feature of hypoxia in TME remains as the main obstacle of many therapeutics like photodynamic therapy. Herein, a specific two-dimensional (2D) phototheranostics (GO-MnO2@tLyP-1/Ce6, denoted as GMtC) with the function of oxygen self-producing and tumor barrier-breaking was detailed by integrating the nanoenzyme MnO2 colloids, tumor homing-penetrating peptide tLyP-1 and photosensitizer chlorin e6 (Ce6) to tackle the hypoxic tumors. GMtC was capable to accumulate into the inner of murine mammary 4T1 tumor spheroids (and the depth could be as far as 90 µm) and to relieve the hypoxia state by catalytic decomposition of endogenous H2O2 to oxygen, which subsequently enhanced the yield of cytotoxic singlet oxygen under laser irradiation. In vivo dual-modal imaging of magnetic resonance and biofluorescence demonstrated the targeted accumulation and distribution of GMtC in tumor regions, thus facilitating the tumor hypoxia alleviation. Notably, GMtC achieved the highest photodynamic anticancer efficiency against 4T1 tumors without obvious systemic toxicity compared with the non-penetrating and no oxygen-generating counterparts. This study suggests the great promise of GMtC as an endogenous TME-responsive and exogenous laser-triggered theranostic platform against the solid hypoxic tumors. Statement of significanceThe hostile tumor hypoxia not only induces the tumor angiogenesis, invasiveness and irreversible metastasis, but also inherently impairs the efficiency of many therapeutic modalities like photodynamic therapy (PDT). Though numerous hypoxia-alleviating strategies based on nanomedicine have been proposed, little attention is paid to the hypoxia-specific transportation barriers. This study develops a type of 2D phototheranostics GMtC against hypoxic solid tumors by integrating the function of tumor homing-penetrating and in situ oxygen-generating. GMtC displays outstanding performance in tumor deep penetration to hypoxia center and generating abundant oxygen in responsive to tumor microenvironment, thus exerting the highest efficiency of PDT against 4T1 mammary tumor. GMtC can be a potent theranostics to treat the solid hypoxic tumors.

Peroxidase Activity of Myoglobin Variants Reconstituted with Artificial Cofactors.

Myoglobin (Mb) can react with hydrogen peroxide (H2O2) to form a highly active intermediate compound and catalyse oxidation reactions. To enhance this activity, known as pseudo‐peroxidase activity, previous studies have focused on the modification of key amino acid residues of Mb or the heme cofactor. In this work, the Mb scaffold (apo‐Mb) was systematically reconstituted with a set of cofactors based on six metal ions and two ligands. These Mb variants were fully characterised by UV‐Vis spectroscopy, circular dichroism (CD) spectroscopy, inductively coupled plasma mass spectrometry (ICP‐MS) and native mass spectrometry (nMS). The steady‐state kinetics of guaiacol oxidation and 2,4,6‐trichlorophenol (TCP) dehalogenation catalysed by Mb variants were determined. Mb variants with iron chlorin e6 (Fe−Ce6) and manganese chlorin e6 (Mn−Ce6) cofactors were found to have improved catalytic efficiency for both guaiacol and TCP substrates in comparison with wild‐type Mb, i. e. Fe‐protoporphyrin IX‐Mb. Furthermore, the selected cofactors were incorporated into the scaffold of a Mb mutant, swMb H64D. Enhanced peroxidase activity for both substrates were found via the reconstitution of Fe−Ce6 into the mutant scaffold.

Study of acute toxicity of monocationic chlorin e6 derivative, a perspective photosensitizer for antimicrobial and antitumor photodynamic therapy

In this experimental work the acute toxicity of a chemically modified derivative of the natural pigment chlorophyll a called monocationic chlorin e6, which is a promising photosensitizer (PS) for antimicrobial and antitumor photodynamic therapy, was studied using white rats. The advantages of the PS under investigation are an intense absorption in the long-wavelength region of the visible spectrum, a sufficiently high quantum yield of singlet oxygen generation, pronounced amphiphilic properties along with an appropriate solubility in water, and a high level of photocytotoxic- ity in relation to both malignant HeLa cells and antibiotic-resistant hospital strains of E. сoli bacteria., P. aerugenosa and others. It has been shown that the value of LD 50 of the considered PS can be calculated as the value of 100 mg/kg. In the reproduced experimental model of acute toxicity, pathomorphological changes in the vital organs of laboratory animals indicate a pronounced vasopathic effect of the drug with the development of cerebral edema and respiratory distress syndrome, which have become the main signs of thanatogenesis.

Constructing a nanocage-based universal carrier for delivering TLR-activating nucleic acids to enhance antitumor immunotherapy

Toll-like receptors (TLRs) have recently emerged as one of the potential targets for immune activation. Therefore, TLR agonists have gotten much attention in the immunotherapy field, and have been proven effective in activating antigen-presenting cells (e.g., dendritic cells) and extensively studied for immune adjuvants. However, the applications of TLR-activating nucleic acids are severely limited by their poor effectiveness and utilization in vivo. Herein, we rationally bioengineered the natural nanocage-like protein, human heavy chain ferritin (HFn), with a positively charged cavity to construct a series of HFn(+) mutants for the internal encapsulation of TLR-activating nucleic acids via electrostatic interaction. Through systematic screenings, we selected the optimal HFn(+) nanocarrier and identified its universal loading ability for different types of TLR-activating nucleic acids. Through in vitro and in vivo experiments, we found that HFn(+) nanocarrier has significantly improved the delivery efficiency of TLR-activating nucleic acids, achieving efficient cell uptake, specific lysosomal localization and enhanced immune activation. Moreover, by virtue of its cage-like spatial structure, TLR-activating nucleic acid loaded HFn(+) shows great potential in combination with the other existing immune strategies via externally modifying function modules. In this study, we conjugated photodynamic photosensitizer chlorin e6 (Ce6) on the external surface of the HFn(+) carrier as an immunogenic death (ICD) inducer. The results show that the HFn(+)-based all-in-one platform effectively synergized TLR agonist-mediated and ICD-mediated immune activation, as evidenced by inducing significantly systemic immune responses, antitumor abscopal effect, and anti-metastasis efficacy in vivo. In conclusion, this nanocage-based carrier is a convenient and universal vehicle to effectively deliver different TLR-activating nucleic acids in vivo and may serve as a novel strategy for the combination of antitumor immunotherapies.

Tumor-associated macrophage-targeted photodynamic cancer therapy using a dextran sulfate-based nano-photosensitizer

The M2-like phenotype of tumor-associated macrophages (TAMs) present in tumors promotes tumor growth and metastasis. Therefore, targeting M2-like TAMs is a potential strategy for cancer therapy. Herein, we fabricated a dextran sulfate-based nano-photosensitizer (dextran sulfate-conjugated chlorin e6, DS-Ce6) to specifically target M2-like TAMs for enhanced photodynamic therapy (PDT). DS-Ce6 was preferentially taken up by interleukin-4-derived M2 macrophages, which overexpressed scavenger receptor-A and selectively targeted macrophages in co-cultured 4T1 tumors/macrophages. The nano-photosensitizer also effectively induced the apoptosis of tumor cells in both monolayer co-culture and three-dimensional co-culture spheroids of tumors/macrophages under laser irradiation. Moreover, the nano-photosensitizer specifically targeted F4/80 and CD206 double-positive M2-like TAMs within tumor tissues. Therefore, the specifically targeted delivery of DS-Ce6 to M2-like TAMs prominently induced tumor apoptosis, leading to excellent phototherapeutic effects in 4T1 tumor-bearing mice after PDT, suggesting the potential of DS-Ce6 for specific targeting of M2-like TAMs and enhanced PDT.

Engineered biomimetic nanoparticles achieve targeted delivery and efficient metabolism-based synergistic therapy against glioblastoma

Glioblastoma multiforme (GBM) is an aggressive brain cancer with a poor prognosis and few treatment options. Here, building on the observation of elevated lactate (LA) in resected GBM, we develop biomimetic therapeutic nanoparticles (NPs) that deliver agents for LA metabolism-based synergistic therapy. Because our self-assembling NPs are encapsulated in membranes derived from glioma cells, they readily penetrate the blood-brain barrier and target GBM through homotypic recognition. After reaching the tumors, lactate oxidase in the NPs converts LA into pyruvic acid (PA) and hydrogen peroxide (H2O2). The PA inhibits cancer cell growth by blocking histones expression and inducing cell-cycle arrest. In parallel, the H2O2 reacts with the delivered bis[2,4,5-trichloro-6-(pentyloxycarbonyl)phenyl] oxalate to release energy, which is used by the co-delivered photosensitizer chlorin e6 for the generation of cytotoxic singlet oxygen to kill glioma cells. Such a synergism ensures strong therapeutic effects against both glioma cell-line derived and patient-derived xenograft models.