Selective Photodynamic Activity of Tetrakis(4-aminophenyl)porphyrins with and without Acetyl Protecting Groups on Cancer and Normal Cells.

Tetrakis(4-aminophenyl)porphyrin (1) and tetrakis(4-acetamidophenyl)porphyrin (2) were dissolved in water with the incorporation of a polysaccharide (λ-carrageenan (CGN)) as a water-solubilizing agent. Although the photodynamic activity of the CGN-2 complex was considerably lower than that of the CGN-1 complex, the selectivity index (SI; IC50 in a normal cell/IC50 in a cancer cell) of the CGN-2 complex was considerably higher than that of the CGN-1 complex. This is because the photodynamic activity of the CGN-2 complex was significantly affected by the intracellular uptakes by the normal and cancer cells. During in vivo experiments, the CGN-2 complex inhibited tumor growth under light irradiation with high blood retention compared with the CGN-1 complex and Photofrin, which exhibited lower blood retention. This study showed that the photodynamic activity and SI are influenced by substituent groups of arene in the meso-positions of porphyrin analogs.

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 exhibits 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 demonstrates 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.

Improvement of Photodynamic Activity by a Stable System Consisting of a C60 Derivative and Photoantenna in Liposomes.

A dyad system comprising a lipid membrane-incorporated fullerene derivative with an N,N-dimethylpyrrodinium group (C60-1) and a photoantenna molecule (DiD) did not exhibit the high photodynamic activity expected based on its singlet oxygen generation ability. Comparison with a fullerene derivative with an amide substituent (C60-2) suggested the cause to be that some of the fullerene derivative had been released from the liposomes, partly disrupting the dyad system. The dyad system of C60-2 and DiD exhibited about twice the photodynamic activity toward HeLa cells as that of C60-1 and DiD, due to the suppression of the release of the fullerene derivative from the liposomes. The hydrophobicity/hydrophilicity balance of the substituent in fullerene derivatives was shown to be very important to obtain a dyad system in liposomes characterized by high photodynamic activity.

Mechanism toward Turn-on of Polysaccharide-Porphyrin Complexes for Fluorescence Probes and Photosensitizers in Photodynamic Therapy in Living Cells.

ß-(1,3-1,6)-D-Glucan, λ-carrageenan, tamarind gum, and pullulan can dissolve various porphyrin derivatives via the formation of complexes in water using a high-speed vibration milling method. The aqueous solutions of the resulting complexes exhibit long-term stability. Despite the adverse effects of the self-quenching process, notable fluorescence and improved photodynamic activity of the polysaccharide-complexed porphyrin derivatives were observed in the presence of liposomes, micelles, cyclodextrins, and HeLa cells. It was noted that the type of porphyrins was more important than the type of polysaccharides present in the complex. Porphyrin self-aggregates were monodispersed in the lipid membranes of the liposomes and lysosomes. The polysaccharide-complexed porphyrin derivatives showed increased photodynamic activity toward HeLa cells under photoirradiation between 610 and 740 nm.

Improved water solubility and photodynamic activity of hydroxy-modified porphyrins by complexation with cyclodextrin.

Porphyrin derivatives with hydroxyphenyl or dihydroxyphenyl moieties in the meso-position were able to dissolve in water by complexation with two trimethyl-ß-cyclodextrins (TMe-ß-CDxs) without further chemical modification of porphyrins or addition of dimethyl sulfoxide as a co-solvent. TMe-ß-CDx-complexed tetra(hydroxyphenyl)porphyrins (THPPs) with phenols in meso-positions have a much higher photodynamic activity than TMe-ß-CDx-complexed tetrakis(dihydroxyphenyl)porphyrins (TDHPPs) with dihydroxyphenyl in the meso-position. The main reason for the different photoactivity is due to the intracellular uptakes of these complexes. Thus phenols in meso-positions of porphyrin derivatives in the complexes were recognized by HeLa cell receptors. Furthermore, the photodynamic activity of TMe-ß-CDx-complexed THPP was much higher than that of THPP injected as a dimethyl sulfoxide solution.

Biofabrication Using Electrochemical Devices and Systems.

Biofabrication is roughly defined as techniques producing complex 2D and 3D tissues and organs from raw materials such as living cells, matrices, biomaterials, and molecules. It is useful for tissue engineering, regenerative medicine, drug screening, and organs-on-a-chip. Biofabrication could be carried out by microfluidic techniques, optical methods, microfabrication, 3D bioprinting, etc. Meanwhile, electrochemical devices and/or systems have also been reported. In this progress report, the recent advances in applying these devices/systems for biofabrication are summarized. After introducing the concept of biofabrication, biofabrication strategies using electrochemical approaches are summarized. Then, various electrochemical systems such as probes and chip devices are described. Next, the biofabrication of hydrogels for 3D cell culture, electrochemical modification on cell culture surfaces, electrodeposition of conductive materials in hydrogels for cell culture, and biofabrication of cell aggregates using dielectrophoresis is discussed. In addition, electrochemical stimulation methods such as electrotaxis are mentioned as promising techniques for biofabrication. Finally, future research directions in this field and the application prospects are highlighted.

Improved Stability and Photodynamic Activity of Water-Soluble 5,15-Diazaporphyrins Incorporated in ß-(1,3-1,6)-d-Glucan with On-Off Switch.

5,15-Diazaporphyrins, which have a large absorption at wavelengths over 600 nm, were dissolved in water by complex formation with ß-(1,3-1,6)-d-glucans. Aqueous solutions of these complexes were relatively stable compared with their trimethyl-ß-cyclodextrin-complexed analogues. ß-Glucan-complexed diazaporphyrins showed quenched fluorescence and had low singlet-oxygen-generation abilities owing to random self-aggregation. However, external stimuli, such as the presence of liposomes or intracellular uptake, restored the fluorescence and singlet-oxygen-generation abilities of ß-glucan-complexed diazaporphyrins. Consequently, ß-glucan-complexed diazaporphyrins showed very high photodynamic activities toward HeLa cells.

Turn-on fluorescence and photodynamic activity of ß-(1,3-1,6)-d-glucan-complexed porphyrin derivatives inside HeLa cells.

Fluorescence intensities of water-soluble ß-(1,3-1,6)-d-glucan (ß-1,3-glucan)-complexed porphyrin derivatives were very weak as a result of self-quenching. However, ß-1,3-glucan-complexed tetra(aminophenyl)porphyrin exhibited 'off-state' to 'on-state' fluorescence switching activity by intracellular uptake. Furthermore, the internalised complex showed a high level of photodynamic activity toward HeLa cells under photoirradiation at long wavelengths.

Stabilisation of lipid membrane-incorporated porphyrin derivative aqueous solutions and their photodynamic activities.

Lipid membrane-incorporated porphyrin derivatives (LMIPors) having three phenyl moieties and one pyridyl or pyridinium moiety at the meso-positions were more stable than LMIPors having phenyl and/or pyridyl moieties. The former two LMIPors showed high photodynamic activity toward cancer cells under photoirradiation at wavelengths over 600 nm, which are the most suitable for photodynamic therapy. The photodynamic activities were greater than that of Photofrin, which is currently the main drug employed clinically as a photosensitiser. The results represent significant progress toward the optimisation of LMIPors as photosensitisers.

Lipid-membrane-incorporated hydrophobic photochromic molecules prepared by the exchange method using cyclodextrins.

It was found that the exchange method for the preparation of lipid-membrane-incorporated guest molecules was applicable not only to fullerenes but also to other hydrophobic molecules such as azobenzene and stilbene. The advantages of this method are that the long-term stability of the lipid-membrane-incorporated azobenzene solution and the maximum ratio of [stilbene]/[lipid] were higher than those prepared by the classical method, which we call the 'premixing method'. Photoisomerisations of these photochromic guest molecules in the lipid membranes maintained the morphology of liposomes.