Water Solubilization of Phthalocyanine Derivatives via Interactions of Long Alkyl Chains and Cyclodextrins: Potential Complexes for Photodynamic Therapy

Monomerization of Phthalocyanines in Water via Their Supramolecular Interactions with Cucurbiturils

Aggregation of phthalocyanines (Pcs) represents a problematic feature that decreases the potential of these macrocycles in a number of applications. In this work, we present a supramolecular approach based on the interaction of aminoadamantyl-substituted Pcs with bulky and hydrophilic cucurbit[7]uril (CB[7]) to increase the levels of Pc monomers in water. A series of zinc(II) Pcs substituted at positions α or β by an aminoadamantyl substituent (with a different level of alkylation of nitrogen) were prepared from the corresponding phthalonitriles. A ¹H nuclear magnetic resonance study of the interaction of phthalonitriles with CB[7] in water confirmed the formation of an inclusion complex with an aminoadamantyl moiety with K_a values of ∼10¹² M^-1. The interaction of CB[7] with Pcs in water substantially weakened H-type aggregation and improved both fluorescence and singlet oxygen production, confirming that this approach is efficient for the monomerization of Pcs. In vitro evaluation of the photodynamic activity of prepared Pcs led to EC₅₀ values in the submicromolar range on HeLa and SK-MEL-28 cells. However, the activity decreased for at least an order of magnitude after host-guest interaction with CB[7] despite better photophysical properties. This was attributed to a much lower uptake by cells due to the very bulky and hydrophilic character of the Pc-CB[7] assembly.

Development of a Water-Dispersible Supramolecular Complex of Polyphenol with Polypeptides for Attenuation of the Allergic Response using a Mechanochemical Strategy

The prevalence of allergic disorders has increased worldwide in recent decades. Polyphenols, including resveratrol and curcumin, are posited to have potential as therapeutic agents for allergy; however, their use has been limited by poor water solubility. Accordingly, a highly concentrated, water dispersible, supramolecular complexes of polyphenols with polypeptides (poly-L-lysine, poly-γ-glutamic acid) and gelatin using high-speed vibration milling are developed. The complex exhibited resistance to photobleaching and thermal radiation. Treatment of a rat basophilic leukemia cell line (RBL-2H3) with polypeptide complexes containing resveratrol is suppressed allergic responses in vitro. Moreover, aerosolized administration of polypeptide complexes is demonstrated excellent bioavailability and inhibition of immediate hypersensitivity reactions in ear tissue in vivo. Furthermore, the method avoids the use of organic solvent and therefore reduces undesirable biological responses.

Formulation of water-dispersible hydrophobic compound nanocomplexes with polypeptides via a supramolecular approach using a high-speed vibration milling technique

Polypeptides were used to solubilize functional hydrophobic molecules via a high-speed vibrational milling method. Poly-l-lysine and poly-γ-glutamic acid, which are polypeptides, were able to prepare more highly concentrated water-dispersible complexes of hydrophobic compounds, including fullerenes, organic dyes, and porphyrin derivatives, than conventional water solubilizers, such as cyclodextrins and pullulan. In addition, the polypeptide systems endowed the complexes with long-term stability and resistance against thermal stress, which is advantageous for industrial applications. Furthermore, complexes of polypeptides and porphyrin derivatives showed a photodynamic activity against cancer cells, and the current system improved the dispersibility and storability of guest molecules without compromising their functionality.

Cyclodextrin-induced release of drug-entrapping liposomes associated with the solation of liposome gels

In this work, we demonstrate that liposome gels in which liposomes are connected by polyethylene glycol terminated by cholesterol groups at both ends can store hydrophilic and hydrophobic drugs in the gel interiors, inner aqueous phases, and lipid membranes. The addition of cyclodextrins (CDxs) as extrinsic stimuli led to the release of drug-entrapping liposomes due to the interactions between CDxs and cholesteryl groups and/or the alkyl chains of lipids. The addition of aqueous solutions of β-CDx, dimethyl-β-CDx, trimethyl-β-CDx, and γ-CDx (final concentration: 7.5 mM) induced the solation of liposome gels and the release of liposomes accompanying the solation. Furthermore, the addition of β-CDx led to the partial release of hydrophilic drugs encapsulated in the liposomes, although the drug release was scarcely observed in other CDxs. In particular, the addition of trimethyl-β-CDx, which has low cytotoxicity, accelerated solation, and cationic liposomes released from the gels were effectively taken up by murine colon cancer (Colon26) cells. Thus, we propose that liposomes released from liposome gels can function as drug carriers.

The solation of liposome gels owing to the addition of trimethyl-β-cyclodextrin (TMe-β-CDx) and the uptake of cationic liposomes released from liposome gels by Colon26 cells are demonstrated.

Theranostic Agent Combining Fullerene Nanocrystals and Gold Nanoparticles for Photoacoustic Imaging and Photothermal Therapy

Developing photoactivatable theranostic platforms with integrated functionalities of biocompatibility, targeting, imaging contrast, and therapy is a promising approach for cancer diagnosis and therapy. Here, we report a theranostic agent based on a hybrid nanoparticle comprising fullerene nanocrystals and gold nanoparticles (FGNPs) for photoacoustic imaging and photothermal therapy. Compared to gold nanoparticles and fullerene crystals, FGNPs exhibited stronger photoacoustic signals and photothermal heating characteristics by irradiating light with an optimal wavelength. Our studies demonstrated that FGNPs could kill cancer cells due to their photothermal heating characteristics in vitro. Moreover, FGNPs that are accumulated in tumor tissue via the enhanced permeation and retention effect can visualize tumor tissue due to their photoacoustic signal in tumor xenograft model mice. The theranostic agent with FGNPs shows promise for cancer therapy.