Design, synthesis, and biological evaluation of folic acid targeted tetraphenylporphyrin as novel photosensitizers for selective photodynamic therapy

Targeted Photodynamic Therapy using a Vectorized Photosensitizer coupled to Folic Acid Analog induces Ovarian Tumor Cell Death and inhibits IL-6-mediated Inflammation

Ovarian cancer (OC) is one of the most lethal cancers among women. Frequent recurrence in the peritoneum due to the presence of microscopic tumor residues justifies the development of new therapies. Indeed, our main objective is to develop a targeted photodynamic therapy (PDT) treatment of peritoneal carcinomatosis from OC to improve the life expectancy of cancer patients. Herein, we propose a targeted-PDT using a vectorized photosensitizer (PS) coupled with a newly folic acid analog (FAA), named PSFAA, in order to target folate receptor alpha (FRα) overexpressed on peritoneal metastasis. This PSFAA was the result of the coupling of pyropheophorbide-a (Pyro-a), as the PS, to a newly synthesized FAA via a polyethylene glycol (PEG) spacer. The selectivity and the PDT efficacy of PSFAA was evaluated on two human OC cell lines overexpressing FRα compared to fibrosarcoma cells underexpressing FRα. Final PSFAA, including the synthesis of a newly FAA and its conjugation to Pyro-a, was obtained after 10 synthesis steps, with an overall yield of 19%. Photophysical properties of PSFAA in EtOH were performed and showed similarity with those of free Pyro-a, such as the fluorescence and singlet oxygen quantum yields (Φf = 0.39 and ΦΔ = 0.53 for free Pyro-a, and Φf = 0.26 and ΦΔ = 0.41 for PSFAA). Any toxicity of PSFAA was noticed. After light illumination, a dose-dependent effect on PS concentration and light dose was shown. Furthermore, a PDT efficacy of PSFAA on OC cell secretome was detected inducing a decrease of a pro-inflammatory cytokine secretion (IL-6). This new PSFAA has shown promising biological properties highlighting the selectivity of the therapy opening new perspectives in the treatment of a cancer in a therapeutic impasse.

Self-assembled porphyrin-based photosensitizer nanomicelles for enhanced photodynamic therapy

Preparation of a supermacromolecular photosensitizer that can stay in the tumor site and exhibits high photoconversion efficiency is useful for improving the efficacy of tumor photodynamic therapy (PDT). In this paper, we prepared tetratroxaminobenzene porphyrin (TAPP) loaded biodegradable silk nanospheres (NSs) and characterized their morphology, optical properties and the singlet oxygen-generating capacity. On this basis, the effect of in vitro photodynamic killing efficacy by as-prepared nanometer micelles was evaluated and the tumor retention ability and tumor killing effect of the nanometer micelles were verified by the co-culture of photosensitizer micelle and tumor cells. The results show that tumor cells were killed well under 660 nm laser irradiation even at a lower concentration of as-prepared TAPP NSs. In addition, due to the excellent safety of as-prepared nanomicelle, they exhibit great potential applications in improved tumor PDT.

Biochemical Basis of Selective Accumulation and Targeted Delivery of Photosensitizers to Tumor Tissues

The method of photodynamic therapy for treatment of malignant neoplasms is based on the selective of accumulation of photosensitizers in the tumor tissue. Insufficient selectivity of photosensitizers in relation to pathologically altered tissues and generalized distribution throughout the body leads to the development of severe toxic effects, including skin phototoxicity. The mechanisms underlying selectivity of photosensitizers for tumor tissue include selective binding to blood proteins and lipoproteins (considering that the number of receptors for those is increased on tumor cell membranes), uptake by macrophages, better solubility at low pH (acidic pH is characteristic of tumor cells), and other mechanisms. At present, increase in the efficiency of photodynamic therapy is largely associated with the additional targeting of photosensitizers to tumor tissues. Targeted delivery strategies are based on the differences in metabolism and gene expression profiles between the tumor and healthy cells. There are differences in expression of receptors, proteases, or transmembrane transporters in these cells. In particular, accelerated metabolism in many types of tumors leads to overexpression of receptors for epidermal growth factor, folic acid, transferrin, and a number of other compounds. This review considers biochemical basis for the selective accumulation of various classes of photosensitizers in tumors (chlorins, phthalocyanines, 5-aminolevulinic acid derivatives, etc.) and discusses various strategies of targeted delivery with emphasis on conjugation of photosensitizers with the receptor ligands overexpressed in tumor cells.

Residual Microscopic Peritoneal Metastases after Macroscopic Complete Cytoreductive Surgery for Advanced High-Grade Serous Ovarian Carcinoma: A Target for Folate Receptor Targeted Photodynamic Therapy?

Despite conventional treatment combining complete macroscopic cytoreductive surgery (CRS) and systemic chemotherapy, residual microscopic peritoneal metastases (mPM) may persist as the cause of peritoneal recurrence in 60% of patients. Therefore, there is a real need to specifically target these mPM to definitively eradicate any traces of the disease and improve patient survival. Therapeutic targeting method, such as photodynamic therapy, would be a promising method for such a purpose. Folate receptor alpha (FRα), as it is specifically overexpressed by cancer cells from various origins, including ovarian cancer cells, is a good target to address photosensitizing molecules. The aim of this study was to determine FRα expression by residual mPM after complete macroscopic CRS in patients with advanced high-grade serous ovarian cancer (HGSOC). A prospective study conducted between 1 June 2018 and 10 July 2019 in a single referent center accredited by the European Society of Gynecological Oncology for advanced EOC surgical management. Consecutive patients presenting with advanced HGSOC and eligible for complete macroscopic CRS were included. Up to 13 peritoneal biopsies were taken from macroscopically healthy peritoneum at the end of CRS and examined for the presence of mPM. In case of detection of mPM, a systematic search for RFα expression by immunohistochemistry was performed. Twenty-six patients were included and 26.9% presented mPM. In the subgroup of patients with mPM, FRα expression was positive on diagnostic biopsy before neoadjuvant chemotherapy for 67% of patients, on macroscopic peritoneal metastases for 86% of patients, and on mPM for 75% of patients. In the subgroup of patients with no mPM, FRα expression was found on diagnostic biopsy before neoadjuvant chemotherapy in 29% of patients and on macroscopic peritoneal metastases in 78% of patients. FRα is well expressed by patients with or without mPM after complete macroscopic CRS in patients with advanced HGSOC. In addition to conventional cytoreductive surgery, the use of a therapeutic targeting method, such as photodynamic therapy, by addressing photosensitizing molecules that specifically target FRα may be studied.

A ruthenium phthalocyanine functionalized with a folic acid unit as a photosensitizer for photodynamic therapy: Synthesis, characterization and in vitro evaluation

A folate-targeted ruthenium(II) phthalocyanine (Ru(FA-Py)(DMSO)(PEG)[Formula: see text]Pc), endowed with a pyridyl ligand functionalized with one folic acid unit (FA-Py) at one of the two axial coordination sites, and a dimethylsulfoxide (DMSO) ligand coordinated to the other axial position, respectively, is described. In order to enhance its biocompatibility, the RuPc is donated with eight PEG chains attached at the peripheral positions. The observed singlet oxygen quantum yields of the PS measured in DMSO and in water are of 0.74 and 0.36, respectively, in line with those observed for other RuPcs bearing comparable axial and peripheral substitution. In vitro PDT activity of the compound has been evaluated in HT-1376 human bladder cancer cell line. Ru(FA-Py)(DMSO)(PEG)[Formula: see text]Pc revealed a slightly higher cellular uptake than those observed for the corresponding carbohydrate-substituted PSs and a better photodynamic activity compared to the glucose-functionalized RuPc.

New Bioconjugated Technetium and Rhenium Folates Synthesized by Transmetallation Reaction with Zinc Derivatives

The zinc dithiocarbamates functionalized with folic acid 2_Zn and 3_Zn were synthesized with a simple straightforward method, using an appropriated folic acid derivative and a functionalized zinc dithiocarbamate (1_Zn). Zinc complexes 2_Zn and 3_Zn show very low solubilities in water, making them useful for preparing Tc-99m radiopharmaceuticals with a potentially high molar activity. Thus, the transmetallation reaction in water medium between the zinc complexes 2_Zn or 3_Zn and the cation fac-[^99mTc(H₂O)₃(CO)₃]⁺, in the presence of the monodentate ligand TPPTS, leads to the formation of the 2 + 1 complexes fac-[^99mTc(CO)₃(SS)(P)] bioconjugated to folic acid (2_Tc and 3_Tc). In spite of the low solubility of 2_Zn and 3_Zn in water, the reaction yield is higher than 95%, and the excess zinc reagent is easily removed by centrifugation. The Tc-99m complexes were characterized by comparing their HPLC with those of the homologous rhenium complexes (2_Re and 3_Re) previously synthesized and characterized by standard methods. Preliminary in vivo studies with 2_Tc and 3_Tc indicate low specific binding to folate receptors. In summary, Tc-99m folates 2_Tc and 3_Tc were prepared in high yields, using a one-pot transmetallation reaction with low soluble zinc dithiocarbamates (>1 ppm), at moderate temperature, without needing a subsequent purification step.

Novel dual-mode antitumor chlorin-based derivatives as potent photosensitizers and histone deacetylase inhibitors for photodynamic therapy and chemotherapy

The combination of photodynamic therapy (PDT) and chemotherapy is a prospective strategy to improve antitumor efficacy. Herein, a series of novel cytotoxic chlorin-based derivatives as dual photosensitizers (PSs) and histone deacetylase inhibitors (HDACIs) were synthesized and investigated for biological activity. Among them, compound 15e showed definite HDAC2 and 10 inhibitory activities by up-regulating expression of acetyl-H4 and highest phototoxicity and dark-toxicity, which was more phototoxic than Talaporfin as a PS while with stronger dark-toxicity compared to vorinostat (SAHA) as a HDACI. The biological assays demonstrated that 15e was liable to enter A549 cells and localized in mitochondria, lysosomes, golgi and endoplasmic reticulum (ER) etc. multiple organelles, resulting in higher cell apoptosis rate and ROS production compared to Talaporfin. Moreover, it could induce tumor cell autophagy as a dual PS and HDACI. All results suggested that compound 15e could be applied as a potential dual cytotoxic drug for PDT and chemotherapy.

Chemical approaches for the enhancement of porphyrin skeleton-based photodynamic therapy

With the development of photodynamic therapy (PDT), remarkable studies have been conducted to generate photosensitisers (PSs), especially porphyrin PSs. A variety of chemical modifications of the porphyrin skeleton have been introduced to improve cellular delivery, stability, and selectivity for cancerous tissues. This review aims to highlight the developments in porphyrin-based structural modifications, with a specific emphasis on the role of PDT in anticancer treatment and the design of PSs to achieve a synergistic effect on multiple targets.

Conjugated Photosensitizers for Imaging and PDT in Cancer Research

Early cancer detection and perfect understanding of the disease are imperative toward efficient treatments. It is straightforward that, for choosing a specific cancer treatment methodology, diagnostic agents undertake a critical role. Imaging is an extremely intriguing tool since it assumes a follow up to treatments to survey the accomplishment of the treatment and to recognize any conceivable repeating injuries. It also permits analysis of the disease, as well as to pursue treatment and monitor the possible changes that happen on the tumor. Likewise, it allows screening the adequacy of treatment and visualizing the state of the tumor. Additionally, when the treatment is finished, observing the patient is imperative to evaluate the treatment methodology and adjust the treatment if necessary. The goal of this review is to present an overview of conjugated photosensitizers for imaging and therapy.

Intracellular Delivery of Adamantane-Tagged Small Molecule, Proteins, and Liposomes Using an Octaarginine-Conjugated β-Cyclodextrin

Herein, we demonstrate a convenient technique for the intracellular delivery of proteins and liposomes based on supramolecular host-guest chemistry. First, we prepared the R8-CD^OH carrier molecule, which is a β-cyclodextrin derivative bearing an octaarginine (R8) chain, as a cell-penetrating peptide, at the primary hydroxyl group. The surface amino groups of proteins (GFP, β-gal, and IgG) were then partly modified with adamantane (Ad) tags using 1-Ad-carboxylic acid N-hydroxysuccinimide ester (Ad-NHS). These Ad-tagged proteins were effectively delivered into HeLa cells though supramolecular host-guest interactions with R8-CD^OH. A 100 nm sized liposome bearing Ad-tags on its surface was also delivered into these cells by the action of R8-CD^OH. The present method does not require any genetic manipulation, and only easy chemical modification processes are used to facilitate intracellular delivery; therefore, we believe that the present method is applicable to a variety of bioengineering processes, such as protein-based therapeutics, cellular reprogramming, and genome-editing, among others.

A global approach for the development of photodynamic therapy of peritoneal metastases regardless of their origin

Surgical management of peritoneal metastases raises the problem of the theoretical spread of the entire peritoneal surface. Intraperitoneal photodynamic therapy (IntraPDT) has been limited by the lack of specificity of photosensitizers (PS) and difficulties to bring light into the abdominal cavity. Recent data in ovarian cancer may give development opportunities for IntraPDT. Intraperitoneal PDT could be an option but the level of evidence of research in this topic must increase. Our opinion is that the most important is to have a realistic idea of what we can objectively expect from PDT and the feasibility of its daily application. At the time of personalized medicine, it is mandatory to select population eligible for a targeted PS administration and who could benefit from the process. The design of a specific PS for each subtype of cancers seems essential to avoid side effects on healthy tissue. On the contrary, our progress on lighting solutions can be beneficial for all patients with an indication of IntraPDT regardless of the origin of PM. A common lighting system developed for all cancers eligible for IntraPDT could be adapted with light source of specific wavelength to activate dedicated PS.

Dual function of lectins — new perspectives in targeted photodynamic therapy

Porphyrins and phthalocyanines are photosensitizers (PS) that are used in clinical imaging, detection of cancer cells and are particularly applied in photodynamic therapy (PDT). Many scientists have been focused on the design of different porphyrin compounds. However, similar to other anti-cancer agents, they cannot selectively recognize tumor tissues. Scientists are seeking new methods to overcome this problem and to find appropriate targeted delivery strategies. Plant lectins are especially suitable molecules for such targeting as they preferentially recognize specific antigens on the glycosylated cancer cells. This review will give more detailed information about the dual function of lectins and their interactions with PSs, which is a new perspective in targeted PDT. The implications and potential applications of such studies will also be discussed.

Synthesis and characterization of novel porphyrin-cinnamic acid conjugates

A series of novel porphyrin-cinnamic acid (porphyrin/CA) conjugates (4a-4c) have been synthesized by condensation of 5-(4-Hydroxyphenyl)-10,15,20-triphenyl- porphyrin (1) with different substituted cinnamic acids (CAs) through an alkyl linker due to the biological activities of CAs and the application of porphyrins in photodynamic therapy (PDT) of cancer. Their related zinc (II) complexes (5a-5c) were also prepared. These novel compounds have been fully characterized by ¹H NMR, Infrared (IR), Mass spectra (Ms) and Elemental analysis. The photophysical properties of these target molecules were studied by absorption and Fluorescence spectroscopy. In solution, the effect of pH, ionic strength in acid media and concentration on the aggregation behaviors of 4a has also been investigated by UV-Vis spectra. The broadened and red shifted Soret band indicated the formation of J-aggregates when the pH value was up to 2.0 in THF-aqueous solution. Furthermore, the higher ionic strength of 0.3 M NaCl in acid media resulted in the generation of J-aggregates in THF-aqueous solution. And the significant blue shift of Soret band also demonstrated the formation of H-aggregates of 4a at 1.1 × 10^-4 M in THF.

Tamoxifen-zinc(II) phthalocyanine conjugates for target-based photodynamic therapy and hormone therapy

Although photodynamic therapy has been extensively studied in recent years and preclinical studies have shown promising results, strategies for enhancing PDT outcomes and reducing side effects still urgently need to be developed. In this study, a series of Tamoxifen-zinc(II) phthalocyanine conjugates have been designed and synthesized. In these “double-headed” conjugates, photodynamic therapy agent zinc(II) phthalocyanine and hormone therapy drug Tamoxifen were combined via oligoethylene glycol linkers. The conjugates show high specificity, and some of them show cytotoxic effects against the MCF-7 cells overexpressed Estrogen receptor, due to the targeting and cytostatic Tamoxifen moiety. Upon illumination, all these conjugates show high cytotoxicity due to the photosensitizing phthalocyanine unit. Their structure-activity relationship was also assessed. The results show that [Formula: see text]-substituted Tamoxifen-zinc(II) phthalocyanine conjugates are highly promising anticancer targeting agents which exhibit additive effects of photodynamic therapy and hormone therapy.

N-Methylpyridylporphyrin tailed with folate conjugate as a potential lysosomal-targeted photosensitizer: Synthesis, DNA interaction, singlet oxygen and subcellular localization

In recent years, great interest has been focused on the use of photosensitizers (PS) for photodynamic therapy (PDT) as safe and effective anti-tumor drugs. As a good lysosomal-targeted drug, folic acid (FA) is highly interesting as well. [Formula: see text]-methylpyridylporphyrin tailed with folate conjugate (Me-Por-FA) was newly designed and synthesized and the structure was confirmed by UV-vis, IR, 1H NMR, MS and elemental analysis. The interaction of this porphyrin with calf thymus DNA was the intercalative binding mode, which was confirmed by ultraviolet and fluorescence spectra, and the binding constants [Formula: see text] was 6.24 × 104 L/mol. The singlet oxygen (1O[Formula: see text] generated by Me-Por-FA was determined by 1, 3-diphenylisobenzofuran (DPBF) method using tetrapyridylporphyrin (H[Formula: see text]TMPyP) as a comparison with the following order: H2TMPyP > Me-Por-FA. Stained with LysoTracker[Formula: see text] Green DND-26, Me-Por-FA was mainly distributed over the lysosomes during 4 h, but H[Formula: see text]TMPyP was not. This suggests that Me-Por-FA could be developed as a targeted photosensitizer for precise photodynamic therapy.

Receptor-mediated Uptake of Folic Acid-functionalized Dextran Nanoparticles for Applications in Photodynamic Therapy

In photodynamic therapy (PDT), photosensitizers and light are used to cause photochemically induced cell death. The selectivity and the effectiveness of the phototoxicity in cancer can be increased by a specific uptake of the photosensitizer into tumor cells. A promising target for this goal is the folic acid receptor α (FRα), which is overexpressed on the surface of many tumor cells and mediates an endocytotic uptake. Here, we describe a polysaccharide-based nanoparticle system suitable for targeted uptake and its photochemical and photobiological characterization. The photosensitizer 5, 10, 15, 20-tetraphenyl-21H, 23H-porphyrine (TPP) was encapsulated in spermine- and acetal-modified dextran (SpAcDex) nanoparticles and conjugated with folic acid (FA) on the surface [SpAcDex(TPP)-FA]. The particles are successfully taken up by human HeLa-KB cells, and a light-induced cytotoxicity is observable. An excess of free folate as the competitor for the FRα-mediated uptake inhibits the phototoxicity. In conclusion, folate-modified SpAcDex particles are a promising drug delivery system for a tumor cell targeted photodynamic therapy.

Plug-and-Play Continuous Gas Flow Assembly of Cysteine-Inserted AuCu Nanobimetals for Folate-Receptor-Targeted Chemo-Phototherapy

Conjugatable nanobimetals exhibiting broadband light absorption for use as phototherapeutic platforms were assembled via a plug-and-play continuous gas flow route. Electrically produced AuCu nanobunches (NBs) under nitrogen gas flow were directly injected into cysteine (cys) solution through gas pressurization to mechanically spray the solution (AuCu into cys droplets). The sprayed droplets were then exposed to 185 nm UV light (higher photon energy [6.2 eV] than the work functions of Au [5.1 eV] and Cu [4.7 eV]) to initiate photoionization of AuCu NBs for subsequent electrostatic reaction with the SH^- group of cys to form cys-inserted AuCu (AuCu-cys) platforms in a single-pass gas stream. These platforms exhibited broadband light absorption spectra because of hybridized interparticle plasmonic coupling and could be conjugated to folic acid (FA) when dispersed in FA solution to form highly dispersible, biocompatible, and cancer-targetable AuCu-cys-FA. This material was suitable for use in targeted phototherapy of folate-receptor (FR)-rich cancers via FR-mediated endocytosis, and loading doxorubicin (DOX) into AuCu-cys-FA (i.e., AuCu-cys-DOXFA) facilitated chemo-phototherapy because of photoresponsive anticancer drug release upon induction of hyperthermia.

Biotinylated-cationic zinc(II) phthalocyanine towards photodynamic therapy

Targeting biotin receptors in cancer cells can improve specifying of photosensitizers (PSs) for cancer treatment by photodynamic therapy (PDT) applications. Consequently, there has been extensive research focusing mainly on the design of PSs with optimized pharmaceutical properties and better targeting toward cancer cells. Herein a tailored mono-biotinylated zinc(II) phthalocyanine (Pc-1) substituted with six phenoxy-bis(triazolyl) substituents has been synthesized. This Pc-1 has been further modified to its cationic version (Pc-2) through quaternizing of the triazole moiety to gain water solubility. Both non-ionic zinc(II) phthalocyanine (Pc-1) and its cationic derivative (Pc-2) were characterized by standard spectroscopic techniques, namely; FT-IR, 1H and [Formula: see text]C NMR, UV-Vis and MALDI-TOF, and by elemental analysis. The photophysical and photochemical properties were evaluated in DMSO for the non-ionic Pc-1 and in both DMSO and water for the cationic Pc-2.

Tumour-targeting photosensitisers for one- and two-photon activated photodynamic therapy

Efficient receptor-mediated delivery of a folate-targeted photosensitiser to kill cancer cells following two-photon excitation in the near-infrared is demonstrated.

Photodynamic therapy evaluation of methoxypolyethyleneglycol-thiol-SPIONs-gold-meso-tetrakis(4-hydroxyphenyl)porphyrin conjugate against breast cancer cells

Magnetic field enhanced photodynamic therapy is an effective non-invasive technique for the eradication of cancer diseases. In this report, magnetic field enhancement of the photodynamic therapy (PDT) efficacy of a novel methoxypolyethyleneglycol-thiol-SPIONs-gold-meso-tetrakis(4-hydroxyphenyl)porphyrin conjugate (nano-drug) against MCF-7 breast cancer cells was evaluated. The nano-drug exhibited excellent blue and red emissions under suitable ultraviolet (380 nm) and visible (430 nm) excitations and was well taken up by the cells without any significant dark cytotoxicity after 24 h post-incubation. However, after exposure of cells to light for about 15 min, high rate of cell death was observed in a dose-dependent manner. In addition, the cells that were exposed to external magnetic field displayed higher phototoxicity than the non-exposed cells. Altogether, these results suggest that the nano-porphyrin drug system can function as a new promising magnetic-field targeting agent for theranostic photodynamic eradication of cancer diseases.

Assessing Photosensitizer Targeting Using Meso-Tetra(Carboxyphenyl) Porphyrin

Mesotetra(4-carboxyphenyl)porphyrin (mTCPP) is a commercially available small molecule fluorophore and photosensitizer with four free carboxylic acid groups. mTCPP can readily be conjugated with amines for facile attachment of functional groups. In this work, we synthesized and assessed tetravalent, lysine-conjugated mTCPP, for its potential applications in targeted imaging and photodynamic therapy. Fmoc-protected d-lysine or l-lysine was conjugated to mTCPP via amide coupling with the epsilon amine group of lysine, followed by Fmoc deprotection. The resulting compounds did not dissolve well in aqueous solvent, but could be solubilized with the assistance of surfactants, including cholic acid. The l-amino acid transporter (LAT1) can uptake diverse neutral l-amino acids. In vitro studies with U87 cells revealed a non-specific uptake of the hydrophobic Fmoc-protected lysine-conjugated mTCPP precursors, but not d- or l-lysine mTCPP. Likewise, only the Fmoc-protected compounds induced substantial phototoxicty in cells following incubation and irradiation with blue light. These experimental results do not provide evidence to suggest that lysine-mTCPP is able to specifically target cancer cells. However, they do highlight mTCPP as a convenient and accessible framework for assessing molecular targeting of photosensitizers.

Caged siRNAs with single folic acid modification of antisense RNA for photomodulation of exogenous and endogenous gene expression in cells

Photoregulating gene expression using folic acid modified caged siRNA through complex formation of folic acid/folate receptor.

Targeting superoxide dismutase to endothelial caveolae profoundly alleviates inflammation caused by endotoxin

Inflammatory mediators binding to Toll-Like receptors (TLR) induce an influx of superoxide anion in the ensuing endosomes. In endothelial cells, endosomal surplus of superoxide causes pro-inflammatory activation and TLR4 agonists act preferentially via caveolae-derived endosomes. To test the hypothesis that SOD delivery to caveolae may specifically inhibit this pathological pathway, we conjugated SOD with antibodies (Ab/SOD, size ~10nm) to plasmalemmal vesicle-associated protein (Plvap) that is specifically localized to endothelial caveolae in vivo and compared its effects to non-caveolar target CD31/PECAM-1. Plvap Ab/SOD bound to endothelial cells in culture with much lower efficacy than CD31 Ab/SOD, yet blocked the effects of LPS signaling with higher efficiency than CD31 Ab/SOD. Disruption of cholesterol-rich membrane domains by filipin inhibits Plvap Ab/SOD endocytosis and LPS signaling, implicating the caveolae-dependent pathway(s) in both processes. Both Ab/SOD conjugates targeted to Plvap and CD31 accumulated in the lungs after IV injection in mice, but the former more profoundly inhibited LPS-induced pulmonary inflammation and elevation of plasma level of interferon-beta and -gamma and interleukin-27. Taken together, these results indicate that targeted delivery of SOD to specific cellular compartments may offer effective, mechanistically precise interception of pro-inflammatory signaling mediated by reactive oxygen species.

Conjugate of biotin with silicon(IV) phthalocyanine for tumor-targeting photodynamic therapy

In order to improve the efficacy of photodynamic therapy (PDT), biotin was axially conjugated with silicon(IV) phthalocyanine (SiPc) skeleton to develop a new tumor-targeting photosensitizer SiPc-biotin. The target compound SiPc-biotin showed much higher binding affinity toward BR-positive (biotin receptor overexpressed) HeLa human cervical carcinoma cells than its precursor SiPc-pip. However, when the biotin receptors of HeLa cells were blocked by free biotin, >50% uptake of SiPc-biotin was suppressed, demonstrating that SiPc-biotin could selectively accumulate in BR-positive cancer cells via the BR-mediated internalization. The confocal fluorescence images further confirmed the target binding ability of SiPc-biotin. As a consequence of specificity of SiPc-biotin toward BR-positive HeLa cells, the photodynamic effect was also largely dependent on the BR expression level of HeLa cells. The photodynamic activities of SiPc-biotin against HeLa cells were dramatically reduced when the biotin receptors were blocked by the free biotin (IC₅₀: 0.18μM vs. 0.46μM). It is concluded that SiPc-biotin can selectively damage BR-positive cancer cells under irradiation. Furthermore, the dark toxicity of SiPc-biotin toward human normal liver cell lines LO2 was much lower than that of its precursor SiPc-pip. The targeting photodynamic activity and low dark toxicity suggest that SiPc-biotin is a promising photosensitizer for tumor-targeting photodynamic therapy.

Strategies for optimizing the delivery to tumors of macrocyclic photosensitizers used in photodynamic therapy (PDT)

This review briefly summaries the principles and mechanisms of action of photodynamic therapy (PDT) as concerns its application in the oncological field, highlighting its drawbacks and some of the strategies that have been or are being explored to overcome them. The major aim is to increase the efficiency and selectivity of the photosensitizer (PS) uptake in the cancer cells for optimizing the PDT effects on tumors while sparing normal cells. Some attempts to achieve this are based on the conjugation of the PS to biomolecules (small ligands, peptides) functioning as carriers with the ability to efficiently penetrate cells and/or specifically recognize and bind proteins/receptors overexpressed on the surface of cancer cells. Alternatively, the PS can be entrapped in nanocarriers derived from various types of materials that can target the tumor by exploiting the enhanced permeability and retention (EPR) effects. The use of nanocarriers is particularly attractive because it allows the simultaneous delivery of more than one drug with the possibility of combining PDT with other therapeutic modalities.

A Molecular Combination of Zinc(II) Phthalocyanine and Tamoxifen Derivative for Dual Targeting Photodynamic Therapy and Hormone Therapy

The combination of photodynamic therapy and other cancer treatment modalities is a promising strategy to enhance therapeutic efficacy and reduce side effects. In this study, a tamoxifen-zinc(II) phthalocyanine conjugate linked by a triethylene glycol chain has been synthesized and characterized. Having tamoxifen as the targeting moiety, the conjugate shows high specific affinity to MCF-7 breast cancer cells overexpressed estrogen receptors (ERs) and tumor tissues, therefore leading to a cytotoxic effect in the dark due to the cytostatic tamoxifen moiety, and a high photocytotoxicity due to the photosensitizing phthalocyanine unit against the MCF-7 cancer cells. The high photodynamic activity of the conjugate can be attributed to its high cellular uptake and efficiency in generating intracellular reactive oxygen species. Upon addition of exogenous 17β-estradiol as an ER inhibitor, the cellular uptake and photocytotoxicity of the conjugate are reduced significantly. As shown by confocal microscopy, the conjugate is preferentially localized in the lysosomes of the MCF-7 cells.

Preparation and In Vitro Photodynamic Activity of Glucosylated Zinc(II) Phthalocyanines as Underlying Targeting Photosensitizers

Two novel glucosylated zinc(II) phthalocyanines 7a–7b, as well as the acetyl-protected counterparts 6a–6b, have been synthesized by the Cu(I)-catalyzed 1,3-dipolar cycloaddition between the propargylated phthalocyanine and azide-substituted glucoses. All of these phthalocyanines were characterized with various spectroscopic methods and studied for their photo-physical, photo-chemical, and photo-biological properties. With glucose as the targeting unit, phthalocyanines 7a–7b exhibit a specific affinity to MCF-7 breast cancer cells over human embryonic lung fibroblast (HELF) cells, showing higher cellular uptake. Upon illumination, both photosensitizers show high cytotoxicity with IC₅₀ as low as 0.032 µM toward MCF-7 cells, which are attributed to their high cellular uptake and low aggregation tendency in the biological media, promoting the generation of intracellular reactive oxygen species (ROS). Confocal laser fluorescence microscopic studies have also revealed that they have high and selective affinities to the lysosomes, but not the mitochondria, of MCF-7 cells. The results show that these two glucosylated zinc(II) phthalocyanines are potential anticancer agents for targeting photodynamic therapy.

Combination of Fluorescence-Guided Surgery With Photodynamic Therapy for the Treatment of Cancer

Specific visualization of body parts is needed during surgery. Fluorescence-guided surgery (FGS) uses a fluorescence contrast agent for in vivo tumor imaging to detect and identify both malignant and normal tissues. There are several advantages and clinical benefits of FGS over other conventional medical imaging modalities, such as its safety, effectiveness, and suitability for real-time imaging in the operating room. Recent advancements in contrast agents and intraoperative fluorescence imaging devices have led to a greater potential for intraoperative fluorescence imaging in clinical applications. Photodynamic therapy (PDT) is an alternative modality to treat tumors, which uses a light-sensitive drug (photosensitizers) and special light to destroy the targeted tissues. In this review, we discuss the fluorescent contrast agents, some newly developed imaging devices, and the successful clinical application of FGS. Additionally, we present the combined strategy of FGS with PDT to further improve the therapeutic effect for patients with cancer. Taken together, this review provides a unique perspective and summarization of FGS.

Phototoxicity of Liposomal Zn- and Al-phthalocyanine Against Cervical and Oral Squamous Cell Carcinoma Cells In Vitro

Background

Photodynamic therapy (PDT) utilizes light to activate a photosensitizer in the presence of oxygen, and leads to local photodamage by the generation of highly reactive oxygen species (ROS). Liposomal delivery of photosensitizers is adaptable to the treatment of cancers. We examined the phototoxicity of free or liposome-embedded phthalocyanine photosensitizers using HeLa cervical carcinoma and HSC-3 oral squamous cell carcinoma cells.

Material/Methods

Liposomes were composed of palmitoyloleoyphosphatidylcholine (POPC): phosphatidylglycerol (PG), and contained either zinc phthalocyanine (ZnPc) or aluminum phthalocyanine chloride (AlPc). Free or liposomal ZnPc and AlPc were incubated with cells for 24 h at 37°C. Cells incubated with ZnPc were exposed to broadband visible light (350–800 nm; light dose 43.2 J/cm²), whereas cells treated with AlPc were exposed to light at 690 nm (light dose 3.6 J/cm²). The effect of folate receptor-targeted liposomal ZnPc was evaluated with HeLa cells. Cytotoxicity was analyzed by the Alamar Blue assay.

Results

Cell viability, expressed as a percentage of control cells, was calculated according to the formula [(A570–A600) of test cells]×100/[(A570–A600) of control cells]. The relative percentage changes then defined the phototoxic efficacy of the experimental conditions. In HeLa cells, 1 μM free ZnPc and AlPc, reduced cell viability to 52.7±2.1 and 15.4±8.0%, respectively. Liposomal phthalocyanines, at 0.1, 0.5, and 1.0 μM, reduced the viability to 68.0±8.6, 15.1±9.9 and 0% (ZnPc), and to 25.8±8.2, 0 and 0% (AlPc), respectively. In HSC-3 cells, 1 μM free ZnPc and AlPc, reduced cell viability to 22.1±2.8 and 56.6±8.6%, respectively. With 1 μM liposomal ZnPc and AlPc, the viability was reduced to 0 and 21.3±0.3%, respectively.

Conclusions

The embedding of phthalocyanines in liposomes enhanced their phototoxicity and this effect was dependent on cell type.

The Research and Applications of Quantum Dots as Nano-Carriers for Targeted Drug Delivery and Cancer Therapy

Quantum dots (QDs), nano-carriers for drugs, can help realize the targeting of drugs, and improve the bioavailability of drugs in biological fields. And, a QD nano-carrier system for drugs has the potential to realize early detection, monitoring, and localized treatments of specific disease sites. In addition, QD nano-carrier systems for drugs can improve stability of drugs, lengthen circulation time in vivo, enhance targeted absorption, and improve the distribution and metabolism process of drugs in organization. So, the development of QD nano-carriers for drugs has become a hotspot in the fields of nano-drug research in recent years. In this paper, we review the advantages and applications of the QD nano-carriers for drugs in biological fields.

Synthesis and evaluation of a (68)Ga labeled folic acid derivative for targeting folate receptors

Present work evaluates the potential of a newly synthesized (68)Ga-NOTA-folic acid conjugate for PET imaging of tumors over-expressing folate receptors (FRs). NOTA-folic acid conjugate was synthesized and characterized. It was radiolabeled with (68)Ga in ≥ 95% radiolabeling yields. In vitro cell binding studies showed a maximum cell uptake of 1.7±0.4% per million KB cells which was completely blocked on addition of cold folic acid showing specificity towards the FRs. However, further studies in tumor xenografts are warranted in order to assess the potential of (68)Ga-folic acid complex for imaging tumors over-expressing FRs.