Hongyue Zhang

Facile synthesis of chitosan assisted multifunctional magnetic Fe3O4@SiO2@CS@pyropheophorbide-a fluorescent nanoparticles for photodynamic therapy

Novel chlorin photosensitizer pyropheophorbide-a (PPA) coated multifunctional magneto-fluorescent nanoparticles Fe3O4@SiO2@CS@PPA (MFCSPPA) about 50 nm in diameter were strategically designed and prepared for photodynamic therapy (PDT) based on the good solubility and magnetic targeting of Fe3O4@SiO2 nanoparticles, excellent biocompatibility and biodegradability of chitosan (CS) polymer, and the unique fluorescence and photodynamic activity of pyropheophorbide-a. In this work, we found that magneto-fluorescent MFCSPPA has high saturation magnetization of 23.7 emu g−1, and showed super-paramagnetic properties, good dispersion in alcohol and water, excellent water-solubility, improved biocompatibility and good photoluminescence properties. In addition, we demonstrated MFCSPPA mediated singlet oxygen production in solution conditions by using 1,3-diphenylisobenzofuran (DPBF) as a fluorescence detector. Moreover, the in vitro PDT activities against human HeLa cervical cancer cells were investigated by MTT assay. The phototoxicity experiments showed that MFCSPPA has strong photodynamic therapy activity and low dark toxicity, and the cancer cell viability was reduced to 18% after treatment with PDT. Phagocytosis of MFCSPPA experiments indicated that it could be successfully taken up to some extent by HeLa cells with a suitable lipo-hydro partition coefficient and biocompatibility. Acridine orange/ethidium bromide (AO/EB) double fluorescence staining suggested that the cells are all in a state of apoptosis or necrosis after PDT treatment for 6 h. In addition, we studied the formation of reactive oxygen species in HeLa cells after MFCSPPA-PDT treatment; the results suggested that type I and type II photodynamic reactions can occur simultaneously, yet type I photodynamic reactions have a slight edge over type II. The as-prepared magneto-fluorescent MFCSPPA nanoparticles are suitable for simultaneous PDT and medical fluorescence imaging.

Magnetic chitosan/graphene oxide composite loaded with novel photosensitizer for enhanced photodynamic therapy

Photodynamic therapy (PDT) is an increasingly recognized alternative to treat various cancers in clinical practice. Most second-generation photosensitizers (PS) are hydrophobic and have poor targeting selectivity, which limit their efficacy for PDT. In this paper, graphene oxide (GO) coupled with magnetic Fe3O4 nanoparticles and chitosan (CS) (MCGO) was prepared by a one-pot solvothermal method and used as a nanocarrier for loading the new photosensitizer HNPa (λmax = 698 nm), which was first synthesized by our group, and was considered as a good water-soluble drug and an excellent tissue-penetrating agent due to its strong absorption at 698 nm (near-infrared region). The synthesized composite (MCGO–HNPa) showed high stability, good water solubility and biocompatibility, expected magnetic targetability, and good photostability for PDT even in low concentrations. Our research reveals that MCGO nanomaterials can promote the production and release of singlet oxygen (ΦΔ = 62.9%) when compared with free HNPa. In addition, the in vitro cell uptake experiments suggested that the MCGO nanomaterials can accelerate the penetration of HNPa drugs into the tumor cell nucleus and that the drug release behavior is pH-sensitive. The MTT assay results against human hepatoma cell lines HepG-2 clearly show that the MCGO–HNPa composite can effectively result in cell damage and apoptotic cell death under light, and that the nanocomposite can improve the PDT antitumor effect of PS agents with negligible dark toxicity. Meanwhile, the research on the photoreaction mechanism reveals that Type I and Type II photodynamic reactions can occur simultaneously in this PDT process, and their relative contributions depend on the type and dose of the photosensitizer. Type II has a greater effect on PDT than Type I, especially for a higher HNPa photosensitizer dose. All the results reveal the promising application of the presented novel strategy.

The anti-cancer potency of photodynamic therapy of a novel chlorin derivative Amidochlorin p6 (ACP)

Photodynamic therapy (PDT) is a minimally invasive method in cancer treatment and has attracted considerable attention recently. In this paper, we have performed a detailed study of photodynamic activity of a chlorophyllous derivative, Amidochlorin p6 (ACP), and evaluated its potential as a photosensitizer in PDT. The singlet oxygen quantum yield (ΦΔ), the photoreaction mechanisms in PDT, the anti-photobleaching ability in phosphate buffer saline (PBS), the photocytotoxicity and dark toxicity against HeLa cells, cellular uptake and the influence on the expression of survivin and cyclin-dependent kinase (CDK2), were all investigated. The title compound showed significant photocytotoxicity and negligible toxicity in dark, and remarkable photostability. Moreover, ACP could be uptaken by HeLa cells successfully at 20 min leading to damage of cancer cells under light, during which Type I and Type II photodynamic reactions occurred simultaneously on HeLa cells in PDT treatment, and the influence of Type I (the generation of hydroxyl radicals) is slightly larger than Type II (the generation of singlet oxygen). In addition, real-time fluorescent quantitative PCR (RT-qPCR) suggested that ACP could significantly regulate the expression of survivin, which partly explained why ACP could induce the HeLa cell apoptosis and accelerate cell death.

Facile synthesis of a highly water-soluble graphene conjugated chlorophyll-a photosensitizer composite for improved photodynamic therapy in vitro

In photodynamic therapy (PDT), selection of an ideal photosensitizer and improvement of its photodynamic activities are currently of great interest. In this work, a chlorophyll-a photosensitizer derivative, p-bromo-phenylhydrazone-methyl pyropheophorbide-a (BPMppa) with a long absorption wavelength (683 nm) and a large molar extinction coefficient (7.03 × 104 M−1 cm−1), which is considered to be more suitable for the treatment of deep cancer, is loaded onto pristine graphene using a direct graphite exfoliation process via π–π stacking in water. The obtained graphene loaded photosensitizer G–BPMppa composite shows significantly improved water-solubility and dispersity in water, PBS and culture medium, and an increased singlet oxygen (1O2) quantum yield (ΦΔ = 60.55%) in DMF solution compared to free BPMppa (ΦΔ = 29.2%). In addition, cell experiments indicated that the G–BPMppa composite could be taken up by HeLa cells successfully, showing enhanced intracellular uptake behavior. Owing to its enhanced intracellular uptake and higher 1O2 quantum yield, G–BPMppa showed remarkably improved PDT efficiency (IC50: 1.36 ± 0.35 μg mL−1 of equivalent BPMppa) over free BPMppa after irradiation, but low dark toxicity without irradiation. Moreover, cell morphological changes after G–BPMppa PDT further qualitatively demonstrated that G–BPMppa could induce damage and apoptotic cell death efficiently. Furthermore, the photochemical mechanism of the G–BPMppa mediated PDT process was investigated by using specific quenching agents, sodium azide (SA, a singlet oxygen quencher) and D-mannitol (DM, a hydroxyl radical quencher); the results indicated that type I and type II photodynamic reactions could occur simultaneously, yet the type II reaction (the generation of 1O2) might play a predominant role in the G–BPMppa induced PDT process.

pH-Sensitive graphene oxide conjugate purpurin-18 methyl ester photosensitizer nanocomplex in photodynamic therapy

Graphene oxide (GO) has been widely recognized as a good drug delivery vector due to its special properties and biocompatibility. Herein, a promising chlorophyll-a derivative photosensitizer, purpurin-18 methyl ester (Pu18), was introduced onto the surface of GO to investigate the drug loading and release properties. Pu18 is considered to be more suitable for the treatment of deeper tissues due to its strong absorption in the near infrared region (Q(0,0) band at 699 nm). The graphene oxide loaded Pu18 nanomaterial (GO–Pu18) was obtained via simple ultrasonic agitation and presented pH-sensitive drug release behavior. Pu18 could be released more easily from the GO–Pu18 composite in a weak acid environment than that in a neutral environment, suggesting that GO–Pu18 could be applied in tumor treatment due to the weak acid environment around tumor tissues. Moreover, GO–Pu18 showed an increased singlet oxygen (1O2) quantum yield (ΦΔ = 62.60%) compared to free Pu18 (ΦΔ = 58.82%) and showed remarkable photostability in phosphate buffer saline (PBS). In vitro experiments on HepG-2 cells showed that the GO–Pu18 composite possessed excellent photocytotoxicity and negligible dark toxicity. Cell morphological changes after PDT treatment also showed that GO–Pu18 could lead to remarkable damage of cancer cells under light, during which Type I (the generation of hydroxyl radicals) and Type II (the generation of singlet oxygen) photodynamic reactions occurred simultaneously, yet the Type II reaction might play a predominant role. The research has disclosed that the new composite GO–Pu18a is a favorable prospect in the treatment of PDT.

Folate chitosan conjugated doxorubicin and pyropheophorbide acid nanoparticles (FCDP–NPs) for enhance photodynamic therapy

We prepared new folate chitosan conjugated doxorubicin (DOX) and pyropheophorbide acid (PPa) nanoparticles (FCDP–NPs) using an ionic gelation method with tripolyphosphate (TPP) to enhance photodynamic therapy activity, based on the considerations of the long absorption wavelength (683 nm) of pyropheophorbide acid (PPa) in water and the excellent chemotherapeutic characteristics of doxorubicin (DOX) in cancer therapy. The obtained FCDP–NPs demonstrated a typical spherosome structure, a strong near infrared (NIR) absorption (705 nm) and significantly improved stability and dispersity in PBS (pH = 5, 7, 9); as well as a high singlet oxygen quantum yield (ΦΔ = 64%) compared to free PPa (ΦΔ = 59.1%). In addition, the in vitro cell experiments suggested that FCDP–NPs could be uptaken by HepG2 cells quickly and were mainly located in the cell nucleus. FCDP–NPs showed improved PDT efficiency over pure PPa and DOX at the same concentration after irradiation. Specifically, FCDP–NPs could lead to a 92% inhibition rate on HepG2 cells at 40 μg mL−1 (equal to 6 μg mL−1 DOX). However, the pure DOX showed little cytotoxicity at 6 μg mL−1, which suggests that a small amount of DOX could effectively enhance the PDT activities of PPa and lead to little “dark” cytotoxicity. Moreover, cell morphological changes after PDT treatment further indicated that FCDP–NPs could induce damage and apoptotic cell death efficiently. Finally, the photochemical mechanism of FCDP–NPs during PDT process was investigated by using specific quenching agents sodium azide (SA, a single oxygen quencher) and D-mannitol (DM, a hydroxyl radicals quencher), respectively. The results suggested that Type I and Type II photodynamic reactions can occur simultaneously, yet Type I reaction (the generation of hydroxyl radicals) might play a more important role. All these studies indicated that the FCDP–NPs could be potential nanoparticles in photodynamic cancer treatment.

Photo-induced synthesis and in vitro antitumor activity of Fenestin A analogs

Two novel Fenestin A analogs (1 and 2) containing a phthalimide moiety are prepared by photoinduced cyclization. Their absolute configurations were determined by experimental ECD with the aid of theoretical calculations. The resulting compounds are active in HeLa (IC50 = 28.2 μM for 1 and 36.5 μM for 2) and HepG-2 cell lines (IC50 = 33.5 μM for 1 and 40.3 μM for 2).

The in vitro photodynamic activity, photophysical and photochemical research of a novel chlorophyll-derived photosensitizer

Chlorophyll has always been used as the leading compound for photodynamic therapy drug development. In this paper, a novel methyl pyropheophorbide-a- derived photosensitizer, 3-acetyl-3-devinyl-131-dicyanomethylene-pyropheophorbide-a was synthesized through modifications at C-131, C-3, and C-17 positions of methyl pyropheophorbide-a. The compound exhibited a longer wavelength absorption at 713 nm (in methanol) than that of methyl pyropheophorbide-a (667 nm) due to the enlarged the aromatic conjugation system by dicyanomethylene, allowing it to be potential in deep tumor treatment. Moreover, benefiting from the carboxylic group at C-17 and the acetyl group at C-3, the title compound was endowed with better water solubility than that of methyl pyropheophorbide-a. Detailed in vitro photodynamic therapy research showed ADCPPa could be uptaken by cancer cells successfully and killed the cancer cells more efficiently than the leading compound methyl pyropheophorbide-a under light (light dose 10 J/cm2) due to the high singlet oxygen quantum yield (65.98%). The excellent anti-photobleaching ability (degradation rate 1.6% in 10 min) also boosted its potential in practical application. In addition, the research has disclosed that during photochemical processes of photodynamic therapy, the formation of singlet oxygen after photodynamic therapy treatment played a major role, comparing with the formation of superoxide anion and radicals. Finally, the real time quantitative polymerase chain reaction (RT-qPCR) experiments have showed that the target compound has important regulating effect on expression of CDK2 and Survivin, consequently leading to apoptosis and cell death.

The photodynamic therapy activity of 3-(1-hydroxylethyl)-3-devinyl-131-(dicyanomethylene) pyropheophorbide-a methyl ester (HDCPPa) against HeLa cell in vitro

Photodynamic therapy (PDT) has been a potential therapeutic method for the treatment of various cancers, with photosensitizer being the key component in photodynamic therapy. In this paper, we prepared a photosensitizer 3-(1-hydroxylethyl)-3-devinyl-131-(dicyanomethylene) pyropheophorbide-a methyl ester (HDCPPa), based on chlorophyll pyropheophorbide-a according to the previous report, and systematically investigated the fluorescence emission spectrum and ultraviolet absorption spectrum HDCPPa has long absorption in the near-infrared spectral region (around 695 nm). The excitation wavelength and the emission wavelength were 415 nm and 699 nm respectively in dichloromethane, 1O2 quantum yield was 63.5%. HDCPPa also had high stability in PBS solution, DMEM cell culture medium and normal saline (NS) in vitro. After irradiation by the light of 675 nm (10 J.cm−2) for 70 min the degradation rate of HDCPPa was 12.5%, which indicated that the target compound showed high stability under light. The in vitro photodynamic therapy activities against HeLa cells were also studied, which showed that HDCPPa had extremely low dark toxicity but great phototoxicity, and the cell viability is lower than 10% under the light irradiation of 675 nm (10 J.cm−2). Moreover, HDCPPa can quickly enter the cell after being incubated with HeLa cells in less than 30 min. We also evaluated the mechanism of the photochemical reaction, which had proved that Type II is primarily responsible for the cell death. Therefore HDCPPa could serve as a very promising photosensitizer for photodynamic therapy.