Design of a Gd-DOTA-Phthalocyanine Conjugate Combining MRI Contrast Imaging and Photosensitization Properties as a Potential Molecular Theranostic

Three in One: In Vitro and In Vivo Evaluation of Anticancer Activity of a Theranostic Agent that Combines Magnetic Resonance Imaging, Optical Bioimaging, and Photodynamic Therapy Capabilities

Cancer treatment is a crucial area of research and development, as current chemotherapeutic treatments can have severe side effects or poor outcomes. In the constant search for new strategies that are localized and minimally invasive and produce minimal side effects, photodynamic therapy (PDT) is an exciting therapeutic modality that has been gaining attention. The use of theranostics, which combine diagnostic and therapeutic capabilities, can further improve treatment monitoring through image guidance. This study explores the potential of a theranostic agent consisting of four Gd(III) DTTA complexes (DTTA: diethylenetriamine-N,N,N″,N″-tetraacetate) grafted to a meso-tetraphenylporphyrin core for PDT, fluorescence, and magnetic resonance imaging (MRI). The agent was first tested in vitro on both nonmalignant TIB-75 and MRC-5 and tumoral CT26 and HT-29 cell lines and subsequently evaluated in vivo in a preclinical colorectal tumor model. Advanced MRI and optical imaging techniques were employed with engineered quantitative in vivo molecular imaging based on dynamic acquisition sequences to track the biodistribution of agents in the body. With 3D quantitative volume computed by MRI and tumoral cell function assessed by bioluminescence imaging, we could demonstrate a significant impact of the molecular agent on tumor growth following light application. Further exhaustive histological analysis confirmed these promising results, making this theranostic agent a potential drug candidate for cancer.

Water-Soluble Gd(III)-Porphyrin Complexes Capable of Both Photosensitization and Relaxation Enhancement

With the aim of developing more stable Gd(III)-porphyrin complexes, two types of ligands 1 and 2 with carboxylic acid anchors were synthesized. Due to the N-substituted pyridyl cation attached to the porphyrin core, these porphyrin ligands were highly water-soluble and formed the corresponding Gd(III) chelates, Gd-1 and Gd-2. Gd-1 was sufficiently stable in neutral buffer, presumably due to the preferred conformation of the carboxylate-terminated anchors connected to nitrogen in the meta position of the pyridyl group helping to stabilize Gd(III) complexation by the porphyrin center. ¹H NMRD (nuclear magnetic relaxation dispersion) measurements on Gd-1 revealed high longitudinal water proton relaxivity (r₁ = 21.2 mM^-1 s^-1 at 60 MHz and 25 °C), which originates from slow rotational motion resulting from aggregation in aqueous solution. Under visible light irradiation, Gd-1 showed extensive photoinduced DNA cleavage in line with efficient photoinduced singlet oxygen generation. Cell-based assays revealed no significant dark cytotoxicity of Gd-1, while it showed sufficient photocytotoxicity on cancer cell lines under visible light irradiation. These results indicate the potential of this Gd(III)-porphyrin complex (Gd-1) as a core for the development of bifunctional systems acting as an efficient photodynamic therapy photosensitizer (PDT-PS) with magnetic resonance imaging (MRI) detection capabilities.

Clinical Development of Metal Complexes as Photosensitizers for Photodynamic Therapy of Cancer

Cancer has emerged over the last decades as one of the deadliest diseases in the world. Among the most commonly used techniques (i.e. surgery, immunotherapy, radiotherapy or chemotherapy), increasing attention has been devoted towards photodynamic therapy. However, the vast majority of clinically applied photosensitizers are not ideal and associated with several limitations including poor aqueous solubility, poor photostability and slow clearance from the body, causing photosensitivity. In an effort to overcome these drawbacks, much attention has been devoted towards the incorporation of a metal ion. Herein, the clinical development of metal-containing compounds including Purlytin® , Lutrin® /Antrin® , Photosens® , TOOKAD® soluble or TLD-1433 is critically reviewed.

Recent Strategies to Develop Innovative Photosensitizers for Enhanced Photodynamic Therapy

This review presents a robust strategy to design photosensitizers (PSs) for various species. Photodynamic therapy (PDT) is a photochemical-based treatment approach that involves the use of light combined with a light-activated chemical, referred to as a PS. Attractively, PDT is one of the alternatives to conventional cancer treatment due to its noninvasive nature, high cure rates, and low side effects. PSs play an important factor in photoinduced reactive oxygen species (ROS) generation. Although the concept of photosensitizer-based photodynamic therapy has been widely adopted for clinical trials and bioimaging, until now, to our surprise, there has been no relevant review article on rational designs of organic PSs for PDT. Furthermore, most of published review articles in PDT focused on nanomaterials and nanotechnology based on traditional PSs. Therefore, this review aimed at reporting recent strategies to develop innovative organic photosensitizers for enhanced photodynamic therapy, with each example described in detail instead of providing only a general overview, as is typically done in previous reviews of PDT, to provide intuitive, vivid, and specific insights to the readers.

Recent Advances in Photosensitizers as Multifunctional Theranostic Agents for Imaging-Guided Photodynamic Therapy of Cancer

In recent years tremendous effort has been invested in the field of cancer diagnosis and treatment with an overall goal of improving cancer management, therapeutic outcome, patient survival, and quality of life. Photodynamic Therapy (PDT), which works on the principle of light-induced activation of photosensitizers (PS) leading to Reactive Oxygen Species (ROS) mediated cancer cell killing has received increased attention as a promising alternative to overcome several limitations of conventional cancer therapies. Compared to conventional therapies, PDT offers the advantages of selectivity, minimal invasiveness, localized treatment, and spatio-temporal control which minimizes the overall therapeutic side effects and can be repeated as needed without interfering with other treatments and inducing treatment resistance. Overall PDT efficacy requires proper planning of various parameters like localization and concentration of PS at the tumor site, light dose, oxygen concentration and heterogeneity of the tumor microenvironment, which can be achieved with advanced imaging techniques. Consequently, there has been tremendous interest in the rationale design of PS formulations to exploit their theranostic potential to unleash the imperative contribution of medical imaging in the context of successful PDT outcomes. Further, recent advances in PS formulations as activatable phototheranostic agents have shown promising potential for finely controlled imaging-guided PDT due to their propensity to specifically turning on diagnostic signals simultaneously with photodynamic effects in response to the tumor-specific stimuli. In this review, we have summarized the recent progress in the development of PS-based multifunctional theranostic agents for biomedical applications in multimodal imaging combined with PDT. We also present the role of different imaging modalities; magnetic resonance, optical, nuclear, acoustic, and photoacoustic in improving the pre-and post-PDT effects. We anticipate that the information presented in this review will encourage future development and design of PSs for improved image-guided PDT for cancer treatment.

Insight into the effects of the anchoring groups on the photovoltaic performance of unsymmetrical phthalocyanine based dye-sensitized solar cells

Push-pull zinc phthalocyanine dyes bearing hexylsulfanyl moieties as electron donors and carboxyethynyl as mono- or di-anchoring groups have been designed, synthesized and tested as sensitizers in dye-sensitized solar cells (DSSCs). The effects of the anchoring groups on the optical, electrochemical and photovoltaic properties were investigated. The incorporation of a carboxyethynyl group in GT23 has a considerable effect on preventing dye aggregation due to its relatively non-planar structure. The mono-anchoring dye bearing a phenyl carboxyethynyl group, GT5, has a higher molar extinction coefficient and sufficient charge injection into the TiO2 conduction band. Therefore, GT5 achieved at least 90% higher power conversion efficiency than the di-anchoring dyes (GT31 and GT32). Time-dependent density functional theory (PBE0/6-31G(d,p)) was also used to calculate the electronic absorption spectra, which predicted very well the measured UV-Vis with an error of up to 0.11 eV for the Q bands and 0.3 eV for the B bands. The longest charge transfer bands are obtained in the visible light region and they correspond to a transfer phthalocyanine core → substituent with a carboxyethynyl group where the absorptions of GT32 (465 nm) and GT31 (461 nm) are red-shifted compared to GT23 (429 nm) and GT5 (441 nm). The interaction energy between the phthalocyanine and a cluster of anatase-TiO2 (H4Ti40O82) was calculated using density functional theory. For all phthalocyanines, the interaction favored is monodentate and corresponds to -O(OH)Ti(TiO2), where the stronger interaction occurs for GT32 (-2.11 eV) and GT31 (-2.25 eV). This study presents the molecular combination of the anchoring groups in zinc phthalocyanine sensitizers, which is one of the effective strategies for improving the performance of DSSCs.

Luminescent Lanthanide Complex Sensor for Acac and Cd2. Photochem Photobiol 2020;97:664-671. [PMID: 33301596 DOI: 10.1111/php.13366]

In this work, phenylmalonic acid (H₂ pmal) and phenanthroline (phen) are selected to react with Ln(NO₃ )₃ ·6H₂ O (Ln = Tb, Eu) to form two lanthanide coordination complex [Ln₂ (PAA)₄ (phen)₂ (NO₃ )₂ ] (Ln = Tb, Tb complex; Eu, Eu complex), PAA = deprotonated phenylacetic acid, phen = 1,10-phenanthroline). Two lanthanide complexes are stable in neutral, acid (pH = 4) and base (pH = 10) water solutions. Especially, Tb complex is a bifunctional sensor for acac and Cd²⁺ , through luminescence "turn on" and "turn off," respectively. Importantly, the limit of detections (LODs) for acac and Cd²⁺ are 90 nm and 0.5 μm, respectively. Furthermore, the sensing mechanisms are discussed in detail.

Synthesis and In Vitro Studies of a Gd(DOTA)-Porphyrin Conjugate for Combined MRI and Photodynamic Treatment

With the aim of developing new molecular theranostic agents, a π-extended Zn(II) porphyrin as photosensitizer for photodynamic therapy (PDT) linked to two GdDOTA-type complexes for magnetic resonance imaging (MRI) detection was synthesized. The relaxivity studies revealed a much higher relaxivity value per Gd ion for this medium sized molecule (19.32 mM^-1 s^-1 at 20 MHz and 298 K) compared to clinical contrast agents-a value which strongly increases in the presence of bovine serum albumin, reaching 25.22 mM^-1 s^-1. Moreover, the photophysical studies showed the strong ability of the molecule to absorb light in the deep red (670 nm, ε ≈ 60000 M^-1 cm^-1) and in the near-infrared following two-photon excitation (920 nm, σ₂ ≈ 650 GM). The conjugate is also able to generate singlet oxygen, with a quantum yield of 0.58 in DMSO. Promising results were obtained in cellular studies, demonstrating that the conjugate is internalized in HeLa cells at micromolar concentration and leads to 70% of cell death following 30 min irradiation at 660 nm. These results confirm the potential of the designed molecule as an imaging and therapeutic agent.

Peripherally carboxylic acid substituted asymmetric zinc(II) phthalocyanines: Synthesis and photophysicochemical properties

Four asymmetric Zn(II) phthalocyanines (Pc1–Pc4) bearing a carboxylic acid group in the peripheral position have been designed and synthesized to investigate the influence of the distance between COOH group and the phthalocyanine core on their photophysical and photochemical properties. The novel phthalocyanine complexes were characterized by [Formula: see text]H, [Formula: see text]C NMR, IR, and UV-vis spectroscopies, elemental analysis and matrix-assisted laser desorption ionization mass spectrometry (MALDI). The aggregation behavior, photophysical and photochemical properties such as fluorescence lifetime and quantum yields and singlet oxygen quantum yields of Pc1–Pc4 were explored in tetrahydrofuran (THF) to the determination of the potential use of these novel phthalocyanines as photosensitizers for different applications such as photovoltaic technologies and photodynamic therapy (PDT). Pc1–Pc4exhibited high singlet oxygen generation quantum yields (0.84, 0.66, 0.88 and 0.65, respectively). Fluorescence quantum yields could be obtained for Pc1, Pc2, Pc3 and Pc4 (0.13, 0.31, 0.10 and 0.25, respectively) in THF.

The unique features and promises of phthalocyanines as advanced photosensitisers for photodynamic therapy of cancer

Phthalocyanines exhibit superior photoproperties that make them a surely attractive class of photosensitisers for photodynamic therapy of cancer. Several derivatives are at various phases of clinical trials, and efforts have been put continuously to improve their photodynamic efficacy. To this end, various strategies have been applied to develop advanced phthalocyanines with optimised photoproperties, dual therapeutic actions, tumour-targeting properties and/or specific activation at tumour sites. The advantageous properties and potential of phthalocyanines as advanced photosensitisers for photodynamic therapy of cancer are highlighted in this tutorial review.

Molecular isomerization triggered by H2S to an NIR accessible first direct visualization of Ca2+-dependent production in living HeLa cells

Few studies determined the role of intracellular labile Ca²⁺ in H₂S homeostasis. Undoubtedly, fluorescent probes are powerful tools for exploring the question because of their unique advantages: non-destruction, visualization, and multi-levels imaging. Herein, a near-infrared (λ_em = 687 nm) and methylene blue chromophore-based fluorescent probe (MB1) for H₂S was rationally developed. Based on its high sensitivity and selectivity, MB1 was employed to image the concentration change of H₂S, upon stimulating it with ionomycin (a specific calcium ionophore). We found that the intracellular labile Ca²⁺ acted as a promotor for H₂S production in living cells. Furthermore, cystathionine γ-lyase (CSE) might have functioned as a positive mediator of Ca²⁺-dependent H₂S production. These direct and visible links for H₂S/Ca²⁺ will help us to understand the complex signaling in a better way.

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

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

Photoproperties, PVP formulation and 19F NMR of a Zn phthalocyanine with 24 magnetically pseudo-equivalent fluorine atoms

In an attempt to investigate its potential as a PDT [Formula: see text]F MRI molecular theranostic, a Zn phthalocyanine with 24 pseudo-equivalent fluorine atoms was designed and prepared. Compared to its H analogues, the fluorinated derivative has a much higher generation of singlet oxygen. [Formula: see text]F NMR signals in CDCl3 showed that all the fluorine atoms are magnetically pseudo-equivalent with only two close fluorine signals. Formulation in PVP (polyvinylpyrrolidone), a FDA-approved additive, enabled water-solubilization of the phthalocyanines but no satisfying [Formula: see text]F NMR signal could be obtained, probably due to self-quenching caused by aggregation.

Molecular Theranostic Agents for Photodynamic Therapy (PDT) and Magnetic Resonance Imaging (MRI)

Magnetic resonance imaging (MRI) is a powerful non-invasive diagnostic tool that can provide important insights for medical treatment monitoring and optimization. Photodynamic therapy (PDT), a minimally invasive treatment for various types of tumors, is drawing increasing interest thanks to its temporal and spatial selectivity. The combination of MRI and PDT offers real-time monitoring of treatment and can give significant information for drug-uptake and light-delivery parameters optimization. In this review we will give an overview of molecular theranostic agents that have been designed for their potential application in MRI and PDT.

Effect of new asymmetrical Zn(ii) phthalocyanines on the photovoltaic performance of a dye-sensitized solar cell

Theoretical and experimental examinations of novel asymmetric Zn(ii) phthalocyanine derivatives substituted with peripherally one carboxyl and six alkylsulfanyl groups have been successfully investigated from the point of view of DSSC performance.

A New Tool in the Quest for Biocompatible Phthalocyanines: Palladium Catalyzed Aminocarbonylation for Amide Substituted Phthalonitriles and Illustrative Phthalocyanines Thereof

The amide peptide bond type linkage is one of the most natural conjugations available, present in many biological synthons and pharmaceutical drugs. Hence, aiming the direct conjugation of potentially biologically active compounds to phthalocyanines, herein we disclose a new strategy for direct modulation of phthalonitriles, inspired by an attractive synthetic strategy for the preparation of carboxamides based on palladium-catalyzed aminocarbonylation of aryl halides in the presence of carbon monoxide (CO) which, to our knowledge, has never been used to prepare amide-substituted phthalonitriles, the natural precursors for the synthesis of phthalocyanines. Some examples of phthalocyanines prepared thereof are also reported, along with their full spectroscopic characterization and photophysical properties initial assessment.

Evaluation of methotrexate-conjugated gadolinium(III) for cancer diagnosis and treatment

Background

Gliomas are one of the most common types of primary brain tumors. It is usually evaluated by gadolinium(III)-based contrast agents by magnetic resonance imaging (MRI) in the clinic. Methotrexate (MTX), as a type of folate analog that inhibits the enzyme dihydrofolate reductase, is widely used as a chemotherapeutic agent to treat gliomas in the experiment.

Purpose

In this study, a novel theranostic agent MTX-DOTA-Gd (MTX-Gd) was synthesized, which integrates magnetic resonance imaging (MRI) with anticancer treatment.

Methods

MTX-Gd was synthesized by connecting MTX and Gd through 1,4,7,10-tetraazacy-clododecane-1,4,7,10-tetraacetic acid (DOTA). The characterization of MTX-Gd was detected by ultraviolet (UV) and infrared spectroscopy (IR). To confirm the antitumor effect of MTX-Gd, the cytotoxicity of MTX-Gd was examined by the MTT assay. The contrast enhancement of the MTX-Gd was measured through MRI in vitro. Then, nude mice bearing C6 tumor xenografts were used to study in vivo imaging capabilities.

Results

The ultraviolet-visible-near infrared radiation (UV-NIR) absorption curve indicated that MTX-Gd had a broad absorption in the region of 500-700 nm. The formation of MTX-Gd was confirmed from the characteristic bands of MTX-DOTA-Gd in the 1413 cm⁻¹ (C-N), 1577 cm⁻¹ (−NH₂), and 3429 cm⁻¹ (N-H), in the fourier-transform infrared (FTIR) spectra. MTX-Gd showed little difference in the cell viability compared with MTX, except for the highest concentration (270 μM). In vitro, the imaging of MTX-Gd was significantly brighter than Gd-DOTA at the same concentration, and the brightness and signal intensity of MRI were increased followed by the increased concentration of MTX-Gd. And it also showed that MTX was not visualized on MRI. The other images revealed that the concentration of 4 mM MTX-Gd had the same imaging effect with the concentration of 10 mM Gd-DOTA. Then, MTX-Gd was injected in nude mice bearing C6 tumor xenografts through the tail vein. Significant contrast enhancement was observed at the tumor site from 0.5 h to 3 h. The signal of tumor area was strongest at 3 h due to accumulation by size effect of macromolecules.

Conclusion

A novel stable and unique theranostic agent (MTX-Gd) was successfully synthe-sized, and it has good stability, strong anticancer ability and excellent magnetic capacity. The methotrexate component of MTX-Gd, as a chemotherapeutic agent, played an important role in targeted therapies of cancer. The DOTA-Gd component of MTX-Gd performed as the MRI contrast agent. The superior MRI imaging performance and synergetic chemical antineoplastic ability of MTX-Gd was revealed, and it has great potential in the diagnosis and treatment of glioma and potentially other cancers, with prospects of clinical application in the near future.

Assessment of the relevance of GaPc substituted with azido-polyethylene glycol chains for photodynamic therapy. Design, synthetic strategy, fluorescence, singlet oxygen generation, and pH-dependent spectroscopic behaviour

New synthetic route and PDT potential of symmetrically and asymmetrically substituted Ga(iii)Pcs with terminal azides.

Fluorination of phthalocyanine substituents: Improved photoproperties and enhanced photodynamic efficacy after optimal micellar formulations

A fluorinated phthalocyanine and its non-fluorinated analogue were selected to evaluate the potential enhancement of fluorination on photophysical, photochemical and redox properties as well as on biological activity in cellular and animal models. Due to the pharmacological relevance, the affinity of these phthalocyanines towards biological membranes (logP_ow) as well as their primary interaction with human serum albumin (HSA) or low-density lipoprotein (LDL) were determined. Water-dispersible drug formulation of phthalocyanines via Pluronic^®-based triblock copolymer micelles was prepared to avoid self-aggregation effects and to improve their delivery. The obtained results demonstrate that phthalocyanines incorporation into tunable-polymeric micelles significantly enhanced their cellular uptake and their photocytotoxicity. The improved biodistribution and photodynamic efficacy of the phthalocyanines-triblock copolymer conjugates was also confirmed in vivo in CT26 bearing BALB/c mice. PDT with both compounds led to tumor growth inhibition in all treated animals. Fluorinated phthalocyanine 2 turned out to be the most effective anticancer agent as the tumors of 20% of mice treated regressed completely and did not appear for over one year after treatment.

Phthalocyanine-chalcone conjugates

A phthalocyanine-chalcone conjugate was previously reported to retain the full photodynamic activity of the phthalocyanine and a slightly lowered antivascular effect of the chalcone. Assuming that it was due to an insufficient release of the chalcone, we described here several grafting modes applied to the preparation of phthalocyanine-chalcone conjugates.

A Theranostic Agent Combining a Two-Photon-Absorbing Photosensitizer for Photodynamic Therapy and a Gadolinium(III) Complex for MRI Detection

The convergent synthesis and characterization of a potential theranostic agent, [DPP-ZnP-GdDOTA](-), which combines a diketopyrrolopyrrole-porphyrin component DPP-ZnP as a two-photon photosensitizer for photodynamic therapy (PDT) with a gadolinium(III) DOTA complex as a magnetic resonance imaging probe, is presented. [DPP-ZnP-GdDOTA](-) has a remarkably high longitudinal water proton relaxivity (19.94 mm(-1)  s(-1) at 20 MHz and 25 °C) for a monohydrated molecular system of this size. The Nuclear Magnetic Relaxation Dispersion (NMRD) profile is characteristic of slow rotation, related to the extended and rigid aromatic units integrated in the molecule and to self-aggregation occurring in aqueous solution. The two-photon properties were examined and large two-photon absorption cross-sections around 1000 GM were determined between 910 and 940 nm in DCM with 1 % pyridine and in DMSO. Furthermore, the new conjugate was able to generate singlet oxygen, with quantum yield of 0.42 and 0.68 in DCM with 1 % pyridine and DMSO, respectively. Cellular studies were also performed. The [DPP-ZnP-GdDOTA](-) conjugate demonstrated low dark toxicity and was able to induce high one-photon and moderate two-photon phototoxicity on cancer cells.

Modulation of singlet oxygen generation and amphiphilic properties of trihydroxylated monohalogenated porphyrins

Two of the properties important for photodynamic therapy applications are systematically investigated on a trihydroxylated monohalogenated porphyrin core. Singlet oxygen generation can be increased thanks to the heavy atom effect, frequently provided by the introduction of halogen atoms on the photosensitizer. We compare the effect of the presence of the four halogen atoms with the analogous halogen-free porphyrin. Cell uptake is crucial as well for successful photodynamic outcome and is directly related to the amphiphilicity of the molecule. The five derivatives bearing H, F, Cl, Br or I atoms are compared in this regard. The presence of iodine atom induces a sharp difference in singlet oxygen generation compared to all the other derivatives investigated, but increases its lipophilicity, still in the limits suitable for biomedical applications.

Design of an amphiphilic porphyrin exhibiting high in vitro photocytotoxicity

A promising photosensitiser, which exhibits extremely suitable properties for photodynamic applications is described.

Hyaluronic acid-functionalized single-walled carbon nanotubes as tumor-targeting MRI contrast agent

A tumor-targeting carrier, hyaluronic acid (HA)-functionalized single-walled carbon nanotubes (SWCNTs), was explored to deliver magnetic resonance imaging (MRI) contrast agents (CAs) targeting to the tumor cells specifically. In this system, HA surface modification for SWCNTs was simply accomplished by amidation process and could make this nanomaterial highly hydrophilic. Cellular uptake was performed to evaluate the intracellular transport capabilities of HA-SWCNTs for tumor cells and the uptake rank was HA-SWCNTs> SWCNTs owing to the presence of HA, which was also evidenced by flow cytometry. The safety evaluation of this MRI CAs was investigated in vitro and in vivo. It revealed that HA-SWCNTs could stand as a biocompatible nanocarrier and gadolinium (Gd)/HA-SWCNTs demonstrated almost no toxicity compared with free GdCl₃. Moreover, GdCl₃ bearing HA-SWCNTs could significantly increase the circulation time for MRI. Finally, to investigate the MRI contrast enhancing capabilities of Gd/HA-SWCNTs, T₁-weighted MR images of tumor-bearing mice were acquired. The results suggested Gd/HA-SWCNTs had the highest tumor-targeting efficiency and T₁-relaxivity enhancement, indicating HA-SWCNTs could be developed as a tumor-targeting carrier to deliver the CAs, GdCl₃, for the identifiable diagnosis of tumor.

The synthesis of an octasubstituted monohydroxylated phthalocyanine designed to investigate the effect of the presence of active moieties

Filling a lack: monofunctionalized octasubstitution, the missing substitution pattern of phthalocyanines.