High Singlet Oxygen Quantum Yield Research Articles

Smart J-aggregate of cyanine photosensitizer with the ability to target tumor and enhance photodynamic therapy efficacy

Photodynamic therapy (PDT) has been demonstrated to be effective for cancer treatment. Design of photosensitizers (PS) featuring tumor targeting, long excitation wavelengths, and high singlet oxygen quantum yields (Φ(1O2)) is the crucial point of highly efficient PDT. However, it is especially difficult to integrate above features into one photosensitizer. Herein, we put forwards a PS J-aggregation method, simultaneously endowing PS with the ability of tumor targeting, the red-shift of spectra, and the increase of Φ(1O2). Cyanine PS 4-((E)-3-((E)-5-iodo-1,3,3-trimethylindolin-2-ylidene)prop-1-en-1-yl)-1-methylquinolin-1-ium iodide (IDMQ) is firstly designed and synthesized by us. IDMQ can form smart response-type J-aggregates under the control of negatively charge in microenvironments. In blood, IDMQ J-aggregates target tumor via “enhanced permeability and retention (EPR)” effect. Then the intracellular IDMQ J-aggregates assembled by RNA facilitate the red shift of absorption peak with deeper penetration, and compared to free state IDMQ, improve the Φ(1O2), resulting in the bathochromic shift of optimal PDT wavelength from 630 (free state IDMQ) to 700 nm (IDMQ J-aggregates). This intelligent J-aggregation method establishes a promising way for endowing photosensitizer with the ability of tumor-targeting and the synchronous improvement of PDT efficacy and further boosts the development of PDT.

In vitro antiproliferative effect of four ball-type phthalocyanines linked by t-butylcatechol and high singlet oxygen production

Four ball-type phthalocyanines (H2Pc, MgPc, CoPc, and ZnPc) containing 4-tert-butylcatechol substituents at alpha-positions were synthesized from 3,3′-(4-tert-butyl-1,2-phenylene)bis(oxy)diphthalonitrile. The structures were elucidated by elemental analysis and ultraviolet-visible, Fourier-transform infrared, proton nuclear magnetic resonance, and Maldi-Tof mass spectroscopies. The photophysicochemical properties of H2Pc, MgPc, and ZnPc were investigated in dimethylsulphoxide. The fluorescence quantum yields (ΦF), triplet state quantum yields (ΦT), and singlet oxygen quantum yields (ΦΔ) with respect to H2Pc, MgPc and ZnPc were experimentally obtained. Furthermore, the degradation quantum yield (Φd) was evaluated for all complexes. Finally, the magnetic circular dichroism spectra of the four Pcs were obtained. Among these ball-type phthalocyanines, MgPc had the highest triplet lifetime and ZnPc had the highest singlet oxygen quantum yield. Moreover, the in vitro antiproliferative effect of ball-type phthalocyanines (H2Pc, MgPc, CoPc, and ZnPc) was evaluated on MCF-7 cell line originated from luminal A breast cancer and MDA-MB-231 cell line originated from triple negative breast cancer. For this purpose, cell viability MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay was used. For all compounds, 0.2, 0.4, 0.8, 1.6, 3.2, 6.4, 12.8, 25.6, 51.2, 102.4 µM concentrations were applied to both cell lines. There was a significant decrease in cell viability for MCF-7 and MDA-MB-231 cells (p < 0.05).

The effect of one-atom substitution on the photophysical properties and electron spin polarization: Intersystem crossing of compact orthogonal perylene/phenoxazine electron donor/acceptor dyad.

A perylene (Pery)-phenoxazine (PXZ) compact orthogonal electron donor/acceptor dyad was prepared to study the relationship between the molecular structures and the spin-orbit charge transfer intersystem crossing (SOCT-ISC), as well as the electron spin selectivity of the ISC process. The geometry of Pery-PXZ (80.0°) is different from the previously reported perylene-phenothiazine dyad (Pery-PTZ, 91.5°), although there is only one atom variation for the two dyads. Pery-PXZ shows a high singlet oxygen quantum yield (84%). Femtosecond transient absorption spectra indicate that the charge separation (CS, faster than 120 fs) is faster than the Pery-PTZ analog (CS, 250 fs) and charge recombination (CR, i.e., SOCT-ISC, 5.98 ns) of Pery-PXZ is slower than the Pery-PTZ analog (CR, 0.9 ns). The intrinsic triplet state lifetime of Pery-PXZ is 242 µs vs the lifetime of 181 µs for the Pery-PTZ analog. Moreover, the triplet state lifetime of Pery-PXZ in the solid polymer matrix is extended to 4.45 ms, which indicates that the triplet state of Pery-PXZ in fluid solution is deactivated not only by the triplet-triplet annihilation effect but also by other factors such as vibration coupled relaxation. Interestingly, with pulsed laser excited time-resolved electron paramagnetic resonance spectroscopy, the electron spin polarization (ESP) pattern of the triplet state of the current dyad is opposite to that of Pery-PTZ. These results demonstrated the rich electron spin chemistry of the ISC of compact electron donor/acceptor dyads, e.g., the ESP is dependent on not only the molecular geometry but also the structure of the electron donor (or acceptor).

3, 3,5 and 2,6 Expanded Aza-BODIPYs Via Palladium-Catalyzed Suzuki-Miyaura Cross-Coupling Reactions: Synthesis and Photophysical Properties.

Novel symmetrical aza-borondipyrromethene (aza-BODIPY) compounds bearing 4-methoxyphenyl, 4-methoxybiphenyl, 2,4-dimethoxybipheny, 4-bromophenyl and N,N-diphenyl-4-biphenylamine groups on the 3, 3,5 and 2,6 positions of aza-BODIPY core were synthesized via Suzuki-Miyaura coupling reactions while unsymmetrical analogues were obtained from the starting mono Br-substituted aza-BODIPY material which was obtained from nitrosolated pyrrole derivative. The characterizations were performed by means of 1H-NMR, 13C-NMR, FTIR and HRMS-TOF-ESI techniques. The spectral properties of the aza-BODIPY derivatives were investigated using absorption and fluorescence spectroscopy. The novel compounds with extended conjugation have broadband absorption in near infrared region and show significant shifts on their absorption and fluorescence spectra compared to unsubstituted analogues. The highest bathochromic shifts were observed π-extended and strong electron donating groups at 3,5 positions of the aza-BODIPY scaffold. Depend on substitution positions of attached groups to the indacene core, the fluorescence quantum yields of chromophores were determined to be drastic changes. The singlet oxygen generation capability of the compounds were evaluated and 2,6-bromine substituted compounds AA1 and CC1 showed high singlet oxygen quantum yields (71% and 74%, respectively). Enhanced photophysical properties such as intense absorption, extended conjugation and singlet oxygen production make the investigated aza-BODIPYs promising candidates for photodynamic therapy applications and organic photovoltaic cells in NIR region.

Detonation nanodiamonds-phthalocyanine photosensitizers with enhanced photophysicochemical properties and effective photoantibacterial activity.

The nanophotosensitizers based on acetophenoxy tetrasubstituted metallophthalocyanines (MPc) and detonation nanodiamonds (DNDs) were successfully formed and their photophysicochemical properties were determined. The zinc(II)Pc and indium(III)Pc complexes along with their nanoconjugates were found to have high singlet oxygen quantum yields (0.72 - 0.84) associated with the heavy central metal effect. The ability of the functional groups present on the DNDs to bind to the bacteria cell and the improved solubility of the nanoconjugates due to DNDs resulted in effective photodynamic antimicrobial therapy (PACT) activity against S. aureus planktonic cells, with the highest log reduction of 9.72 ± 0.02 for the conjugate of InPc conjugate with DNDs after 30 min irradiation. PACT studies were investigated at a dose of 10 μg/mL for each sample. The results suggest that the readily synthesized nanoconjugates can be used as appropriate PACT agents.

A heavy atom free semiconducting polymer with high singlet oxygen quantum yield for photodynamic and photothermal synergistic therapy

Semiconducting polymers have been widely used for phototheranostics due to their strong absorbance in near infrared region, high photostability, excellent photothermal conversion ability. In this paper, a heavy atom free tri-component semiconducting polymer PTVT has been designed and synthesized by a Stille coupling reaction. PTVT has a high singlet oxygen quantum yield (1O2 QY) of 42.2% in DCM remains high 1O2 generation ability for the DSPE-PEG coated PTVT nanoparticles (NPs) obtained by a nanoprecipitation approach. Owing to the PDT and PTT synergistic therapy (photothermal conversion efficiency ~52.6%), PTVT NPs show a low half maximum inhibitory concentration (IC50) of 5.9 μg/mL towards human lung cancer cells (A549) with laser irradiation. And simultaneously the dark toxicity of such NPs is almost negligible even at high concentrations. Furthermore, in vivo study demonstrates that the NPs are able to inhibit tumor proliferation with laser irradiation, compared with the control and dark group, suggesting the low dark toxicity and high phototoxicity of such NPs. The H&E stained pictures of the normal tissues indicate the biosafety of PTVT NPs in that no obvious damage of heart, liver, lung, kidney and spleen was observed. The results provide an approach to designing heavy atom free semiconducting polymers for phototheranostics.

Measurement of singlet oxygen generation of 9(Hydroxymethyl)anthracene substituted silicon phthalocyanine by sono-photochemical and photochemical studies

Sono-photochemical study which combines photochemical and sonochemical studies is a favorable alternative modality to produce high singlet oxygen. However, though there are many articles about the calculation of singlet oxygen quantum yield for Photodynamic therapy (PDT) studies in the literature, there is no study to measure the efficiency of singlet oxygen for Sono-photodynamic therapy (SPDT) method. Therefore, this study aimed to synthesis a complex with improved photochemical properties and then calculates the efficiency of singlet oxygen by both of photochemical and sono-photochemical studies in DMSO and DMF. The designed complex showed remarkably high singlet oxygen quantum yields. The ΦΔ values (0.74 in DMSO, 0.72 in DMF for photochemical study) reached to 0.96 in DMSO, 0.88 in DMF for sono-photochemical study and these results prove that SPDT improves the therapeutic activity due to the sono-photochemical effect. This article will lead to the studies that seek to obtain highly efficient singlet oxygen.

Photodynamic therapy effect of morpholinium containing silicon (IV) phthalocyanine on HCT-116 cells

In this study, we investigated the in vitro potential of axially 1-morpholiniumpropan-2-ol disubstituted silicon (IV) phthalocyanine (SiPc) which was synthesized previously, on HCT-116 cells as a photodynamic therapy (PDT) agent. The singlet oxygen and photodegradation quantum yields of SiPc were calculated using UV-vis spectrophotometer. The cytotoxic and phototoxic effects of SiPc were evaluated by 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide (MTT) assay. Annexin V-FITC/PI double staining kit, cell cycle kit, and mitochondria membrane potential (ΔΨm) assay kit with JC-1 were used to indicate the cell death pathway. Caspase-3 and β-catenin protein expressions were evaluated by western blotting. The singlet oxygen and photodegradation quantum yields of SiPc were calculated as 0.73 and 3.64 × 10-4 in DMSO. The cell viability assays showed that IC50 value of SiPc did not reach to 100 μM without irradiation. However, excellent phototoxicity was observed in the presence of SiPc upon light irradiation. The cells undergoing early/late apoptosis significantly increased in the presence SiPc at 5 μM upon light irradiation. Besides, the proportion of cells at S and G2/M phase increased. Moreover, mitochondria membrane potentials significantly decreased at 1 and 5 μM of SiPc with light irradiation. While caspase-3 expression increased, β-catenin expression significantly decreased on HCT-116 in the presence of SiPc (p < 0.01). The results indicated that the PDT could be related to apoptosis and Wnt/β-catenin signaling pathway. Based on our findings, SiPc exhibited a significant PDT effect on HCT-116 cells therefore, worthy of more detailed study.

Near-Infrared Light-Initiated Upconversion Nanoplatform with Tumor Microenvironment Responsiveness for Improved Photodynamic Therapy.

Photodynamic therapy (PDT) is inflowing the mainstream of the cancer treatments, yet the shallow light penetration, thermal damage to normal cells, poor tumor targeting, and skin phototoxicity compromised the PDT efficacy. This paper designed and prepared an upconversion nanoplatform that could effectively convert 808 nm NIR light to red and green light emission, both of which could excite photosensitizers and exert the PDT curative effects. A thin layer of mesoporous silica covering core-shell nanostructure NaGdF4:Yb,Er@NaGdF4:Yb,Nd upconversion nanoparticles was prepared as the carrier to load the photosensitizer pyropheophorbide-a (PPa), which could be excited by green and red light simultaneously and produce high singlet oxygen (1O2) quantum yield (79.1%). Meanwhile, the chemotherapy drug doxorubicin (DOX) was absorbed in the pores of the SiO2 layer to improve the therapeutic effect, and the folic acid-coupled chitosan (Cs-FA) was modified on the surface of the SiO2 layer to obtain the targeting and biocompatible UCNP@SiO2/PPa&DOX@Cs-FA nanoplatform. The physically adsorbed DOX in the pore channel could be released slowly under faintly acidic or GSH stimuli (84% release of DOX after 16 h), suggesting that the nanoplatform was responsive to the tumor microenvironment. In vitro experiments showed that the combined treatment of PDT and DOX was superior to that of PDT alone or DOX chemotherapy alone, implying a synergistic therapeutic effect. The morphological changes and dye staining research of HeLa cells were consistent with the MTT assay. Therefore, this research provided a strategy for the development of an efficient and safe multifunctional cancer treatment nanoplatform integrating low-intensity light excitation, slow release, targeting, photodynamic therapy, and chemotherapy.

Synthesis, characterization, photophysical and photochemical properties of peripherally tetra benzodioxane substituted metal-free phthalocyanine and its zinc(II) and magnesium(II) derivatives

The phthalonitrile (3) including 2-(methoxymethyl)-2,3-dihydro-1,4-benzodioxane substituent and peripherally tetra substituted metal-free (4), zinc(II) (5) and magnesium(II) (6) phthalocyanines were synthesized. The photophysical (fluorescence quantum yields and lifetimes) and photochemical (singlet oxygen generation and photodegradation) properties of phthalocyanines (4-6) were examined in DMSO solutions. The zinc(II) phthalocyanine (5) showed higher singlet oxygen quantum yield (ΦΔ=0.82) compared to metal-free (4) (ΦΔ=0.13) and magnesium(II) (5) (ΦΔ=0.29) phthalocyanine. Also, the fluorescence quenching behaviors of phthalocyanines (4-6) by 1,4-benzoquinone (BQ) were investigated.

Polypeptide uploaded efficient nanophotosensitizers to overcome photodynamic resistance for enhanced anticancer therapy

Being either minimally invasive or non-invasive, photodynamic therapy (PDT) has garnered much attention in treatment of superficial tumors. However, repeated irradiation of tumors may lead to PDT resistance, mediated by cell survival pathways, and may result in decreased PDT efficiency and increased emotional burden of patients. Herein, we describe a high-performance nanosystem based on N,S-codoped graphene quantum dots (GQDs), established to overcome PDT resistance in cancer via uploading cyclic (RGDfC) peptide. The as-prepared cRGD-GQDs possessed good biocompatibility, high singlet oxygen quantum yield (ΦΔ = 0.95), and excellent pH stability. Owing to the specific binding ability between c(RGDfC) and integrin αvβ3, the cRGD-GQDs could successfully aggregate in tumor cells and continuously generate high levels of reactive oxygen species (ROS). Notably, some PDT resistance-related factors, such as antioxidant proteins (Nrf2, HO-1, and NQO-1) and the pump protein ABCG2, were maintained at a low level after repetitive PDT treatment mediated by cRGD-GQDs. However, significant upregulation of these factors can be determined after repetitive PDT treatment with free GQDs. Thus, the cRGD-GQDs exhibited powerful antitumor PDT effects both in vitro and in vivo by inhibiting the survival pathways of cancer cells. In conclusion, this study presents a potential appealing clinical strategy in overcoming the acquired PDT resistance and has far-reaching significance for the future PDT therapies.

Molecular Design of Conjugated Small Molecule Nanoparticles for Synergistically Enhanced PTT/PDT

HighlightsA donor–acceptor–donor (D–A–D) conjugated small molecule IID-ThTPA with narrow singlet–triplet energy gap is synthesized via acceptor-oriented molecular design.IID-ThTPA nanoparticles exhibit not only competitive photothermal conversion efficiency (35.4%), but also a dramatically high singlet oxygen quantum yield (84.0%).IID-ThTPA nanoparticles enable superior cooperative tumor PTT/PDT eradicating capability both in vitro and in vivo.

Monoterpene-based metallophthalocyanines: Sustainable synthetic approaches and photophysical studies

Tetra-substituted zinc(II) and copper(II) phthalocyanines bearing peripheral alkoxy-monoterpene groups were prepared by conventional vs. non-conventional synthetic approaches (ultrasound and microwave irradiation). The synthesis of (1[Formula: see text]-(–)-myrtenol (a) and (1[Formula: see text],2[Formula: see text],5[Formula: see text]-([Formula: see text]-menthol (b) derived phthalonitrile precursors was performed through ipso-nitro aromatic substitution reactions, with optimal conditions being obtained using ultrasound irradiation, which allowed us to achieve full conversions in 4.5 h, with isolated yields up to 74%. The subsequent cyclotetramerization of monoterpene-based phthalonitriles was carried out using Zn(II) or Cu(II) salts as metal templates, and also using conventional and non-conventional heating methods. Microwave-assisted synthesis was shown to be the most efficient approach, providing complete conversions in 1 h, yielding the target monoterpene-based metallophthalocyanines in up to 70% isolated yields. Furthermore, photophysical and photochemical studies revealed that Zn(II) phthalocyanines possess fluorescence quantum yields in the range of [Formula: see text] 0.27–0.29, while Cu(II) phthalocyanines exhibited room temperature phosphorescence. In addition, the monoterpene-based Zn(II) phthalocyanines led to high singlet oxygen quantum yields ([Formula: see text] 0.55–0.69).

Novel phthalocyanines bearing 1,2,4 triazole substituents: Synthesis, characterization, photophysical and photochemical properties

4-(4,5-Diphenyl-4H-1,2,4-triazol-3-ylthio)phthalonitrile (3) and its non-peripherally tetra substituted zinc(II) phthalocyanine (4) and magnesium(II) phthalocyanine (5) derivatives were prepared. The novel compounds 3–5 were characterized spectroscopically. To determine the photodynamic therapy potential of 4 and 5, their photophysical and photochemical properties were investigated. The magnesium(II) phthalocyanine (5) showed the highest fluorescence quantum yield. In addition, non-peripheral substitution of the 4-(4,5-diphenyl-4H-1,2,4-triazol-3-ylthio) groups on the phthalocyanine ring did not affect the fluorescence properties of the phthalocyanines. The zinc(II) phthalocyanine (4) exhibited the highest singlet oxygen quantum yield value. The 4 and 5 exhibited lower photostability than Std-ZnPc. These results show that the zinc(II) phthalocyanine (4) can be used in photodynamic therapy applications with its singlet oxygen production and photostability.

S-seco-porphyrazine as a new member of the seco-porphyrazine family - Synthesis, characterization and photocytotoxicity against cancer cells.

An important subgroup within the porphyrazine (Pz) family constitutes seco-porphyrazines, in the chemical structure of which one pyrrole unit is opened in the oxidative process. So far, there are only limited data on N-seco- and C-seco-Pzs. Here, the synthesis of a novel member of the Pzs seco-family, represented by an S-seco-tribenzoporphyrazine analogue, 22,23-bis(4-(3,5-dibutoxycarbonylphenoxy)butylsulfanyl)tribenzo[b,g,l]-22,23-dioxo-22,23-seco-porphyrazinato magnesium(II), is reported, with moderate 34% yield. The new derivative was characterized using NMR spectroscopy, UV-Vis spectroscopy, and mass spectrometry. In the photochemical study performed following the indirect chemical method with 1,3-diphenylisobenzofuran, S-seco-Pz revealed a high singlet oxygen quantum yield of 0.27 in DMF. Potential photocytotoxicity of S-seco-Pz was assessed in vitro on three cancer cell lines - two oral squamous cell carcinoma cell lines derived from the tongue (CAL 27, HSC-3) and human cervical epithelial adenocarcinoma cells (HeLa). In the biological study, the macrocycle was tested in its free form and after loading into liposomes. It is worth noting that S-seco-Pz was found to be non-toxic in the dark, with cell viability levels over 80%. The photocytotoxic IC50 values for free S-seco-Pz were 0.61, 0.18, and 4.1µM for CAL 27, HSC-3 and HeLa cells, respectively. Four different liposomal compositions were analyzed, and the cationic liposomes revealed the highest photokilling efficacy, with the IC50 values for CAL 27, HSC-3, and HeLa cells at 0.24, 0.25, and 0.31µM, respectively. The results of the photocytotoxicity study indicate that the new S-seco-tribenzoporphyrazine can be considered as a potential photosensitizer in photodynamic therapy of cancer, along with the developed cationic liposomal nanocarrier.

Photophysico-chemical properties and photoinactivation of Staphylococcus Aureus using zinc phthalocyanines linked silver nanoparticles conjugates

The synthesis of zinc (II) tri (tert-butyl phenoxy) mono cinnamic acid Pc (complex 1) is reported for the first time in this work. Complex 1 and the reported zinc (II) tri (tert-butyl), mono cinnamic acid phthalocyanine (2), zinc (II) mono cinnamic acid substituted phthalocyanine (3) and zinc (II) tetra cinnamic acid substituted phthalocyanine (4) are conjugated to cysteine capped silver nanoparticles (cys-AgNPs) through an amide bond. The photophysicochemical properties and the photodynamic antimicrobial chemotherapy (PACT) activities of the Pc-cys-AgNPs conjugates and the Pcs alone on S. Aureus are reported. Improved triplet and singlet oxygen quantum yields were observed for the conjugated complexes compared to Pcs alone, due to the heavy atom effect of cys-AgNPs. Asymmetric complexes 1,2, 3 and their respective conjugates recorded higher photosensitizing properties and PACT activities compared to 4 and 4-cys-AgNPs, respectively. Higher log reductions and percentage reductions of S. Aureus were recorded for conjugated complexes compared to ZnPcs only, showing enhanced PACT activities due to their higher singlet oxygen quantum yields.

Sn(IV) N-confused porphyrins as photosensitizer dyes for photodynamic therapy in the near IR region.

The utility of Sn(iv) N-confused porphyrin (SnNCP) for use as photosensitizer dyes in photodynamic therapy is investigated. SnNCP has an unusually high singlet oxygen quantum yield of 0.72 in DMSO. IC50 values of 1.6 and 12.8 μM were obtained against MCF-7 cells upon irradiation with 660 and 780 nm LEDs.

Sn4+ complexation with sulfonated-carbon dots in pursuit of enhanced fluorescence and singlet oxygen quantum yield.

Here we report a novel strategy to crosslink the surface of sulfonated-carbon dots (S-CDs) by complexing SnCl4 with sulfonate groups (-SO3-) on the CDs in aqueous solution. The S-CDs show an average photoluminescence (PL) quantum yield of 21% and a mean diameter of 3.8 nm. After being complexed with Sn4+, the as-obtained Sn@S-CDs present a reduced size of 1.8 nm and a higher PL quantum yield of 32%. More interestingly, the Sn@S-CDs show an enhanced singlet oxygen (1O2) quantum yield as high as 37% compared to that of the S-CDs (27%). In the HepG2 cell line as a model, the Sn@S-CDs exhibit a remarkable cell imaging effect and in vitro PDT efficiency. Therefore, our study proposes a simple but effective cross-linking strategy to synthesize CDs incorporated with metal ions, for the purpose of achieving an enhanced fluorescence intensity and a higher 1O2 quantum yield.

A water-soluble pyrazino[2,3-g]quinoxaline photosensitizer for high-efficiency one- and two-photon excited bioimaging and photodynamic therapy.

A water-soluble photosensitizer, PQs-PEG5, based on a novel pyrazino[2,3-g]quinoxaline (PQ) prototype compound (PQs-5), was designed and synthesized. It has strong linear absorption within 400-600 nm and a desirable two-photon absorption cross section (100-1290 GM) within 740-1000 nm, and it exhibits both a high fluorescence quantum yield (∼0.55) and singlet oxygen quantum yield (∼0.47). By carrying out in vitro cell imaging and photodynamic therapy (PDT) experiments on PQs-PEG5 with HeLa and 4T1 cells, it was demonstrated that PQs-PEG5 can present outstanding bioimaging performance and PDT efficacies simultaneously. Under one-photon excitation (1PE) of a 635 nm diode laser (60 mW cm-2, 5 min) or two-photon excitation (2PE) of an 820 nm fs laser (100 mW, 80 MHz, 140 fs, 5 min), PQs-PEG5 (10 μM) could cause HeLa and 4T1 cell death effectively, which indicated its great potential as a novel photosensitizer for both 1PE- and 2PE-PDT applications.

Singlet oxygen generation of subphthalocyanine-fused dimer and trimer

Subphthalocyanine (SubPc) macrocycles are known as an interesting class of nonplanar aromatic dyes. Despite documented high fluorescence and singlet oxygen quantum yields, the properties of SubPcs in photodynamic therapy (PDT) are underestimated, because their absorption bands do not reach a significant wavelength range. With this in mind, we combined a SubPc ring and a SubPc ring by introducing a common benzene ring and obtained a SubPc dimer (2) and trimer (3) with the Q-band at the near-IR region, owing to the expansion of the [Formula: see text] electron conjugated system. In this study, we reported1O2generation abilities of 2 and 3based on the applied absolute singlet oxygen quantum yields ([Formula: see text]absolute). Subsequent research revealed that 2 and 3 showed the potential to generate1O2to not only in toluene but also in DMSO. Although the photocytotoxicity of 2 and 3 were investigated upon photo-irradiation with a low light dose of approximately 1.5 J/cm2, 2 and 3 showed almost negligible toxic properties toward HEp2 cells.