Photodynamic Activity of Fullerenes and Other Molecules Incorporated into Lipid Membranes by Exchange

HER-2-Targeted Boron Neutron Capture Therapy with Carborane-integrated Immunoliposomes Prepared via an Exchanging Reaction

Boron neutron capture therapy (BNCT) is a promising modality for cancer treatment because of its minimal invasiveness. To maximize the therapeutic benefits of BNCT, the development of efficient platforms for the delivery of boron agents is indispensable. Here, carborane-integrated immunoliposomes were prepared via an exchanging reaction to achieve HER-2-targeted BNCT. The conjugation of an anti-HER-2 antibody to carborane-integrated liposomes successfully endowed these liposomes with targeting properties toward HER-2-overexpressing human ovarian cancer cells (SK-OV3); the resulting BNCT activity toward SK-OV3 cells obtained using the current immunoliposomal system was 14-fold that of the l-BPA/fructose complex, which is a clinically available boron agent. Moreover, the growth of spheroids treated with this system followed by thermal neutron irradiation was significantly suppressed compared with treatment with the l-BPA/fructose complex.

Highly aqueously stable C60-polymer nanoparticles with excellent photodynamic property for potential cancer treatment

Fullerenes are a class of carbon nanomaterials that find a wide range of applications in biomedical fields, especially for photodynamic cancer therapy because of its photosensitive effect. However, hydrophobic fullerenes can only be dispersed in organic solvents which hinders their biomedical applications. Here, we report a facile method to prepare highly water-dispersible fullerene (C60)-polymer nanoparticles with hydrodynamic sizes of 50-70 nm. Hydrophilic random copolymers containing different ratios of polyethylene glycol methyl ether methacrylate and 2-aminoethylmethacrylamide were synthesized for conjugating with C60 molecules through efficient nucleophilic Michael addition reaction between amine groups from hydrophilic polymer and carbon-carbon double bonds from C60. As a result, the amphiphilic C60-polymer conjugates could be well dispersed and nano-assembled in water with a C60 concentration as high as 7.8 mg/mL, demonstrating a significant improvement for the solubility of C60 in an aqueous system. Owing to the high C60 content, the C60-polymer nanoparticles showed a strong photodynamic therapy effect on human lung cancer cells (A549) under light irradiation (450 nm) in both 2D cell culture and 3D spheroid culture, while demonstrating ignorable cytotoxicity under dark. This highly efficient and convenient method to prepare water-dispersible C60-polymer conjugates may have a great impact on the future biomedical applications of fullerenes.

Multi-Functional Liposome: A Powerful Theranostic Nano-Platform Enhancing Photodynamic Therapy

Although photodynamic therapy (PDT) has promising advantages in almost non-invasion, low drug resistance, and low dark toxicity, it still suffers from limitations in the lipophilic nature of most photosensitizers (PSs), short half-life of PS in plasma, poor tissue penetration, and low tumor specificity. To overcome these limitations and enhance PDT, liposomes, as excellent multi-functional nano-carriers for drug delivery, have been extensively studied in multi-functional theranostics, including liposomal PS, targeted drug delivery, controllable drug release, image-guided therapy, and combined therapy. This review provides researchers with a useful reference in liposome-based drug delivery.

Bacterial elimination via the photodynamic activity of a fullerene/light-harvesting antenna molecule assembled system integrated into liposome membranes

Ease of transmission and exceptionally high mortality rates make pathogen-based infections an ongoing global threat. Herein, a facile bacterial elimination process is described which is based on the photodynamic activity of fullerenes composed of light-harvesting antenna molecules integrated into liposome membranes. This was done to expand the absorption capabilities of fullerene derivatives. Efficient energy transfer from the photoactivated antenna molecules to the fullerenes enhanced antimicrobial activity without any harmful lytic activity against red blood cells even under irradiation.

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

A porphyrin derivative which exists on the hydrophilic surface of the liposomes showed high photodynamic activity.

Photodynamic Activity of Fullerene Derivatives Solubilized in Water by Natural-Product-Based Solubilizing Agents

Water-soluble fullerenes prepared by using solubilizing agents based on natural products are promising photosensitizers for photodynamic therapy. Cyclodextrin, β-1,3-glucan, lysozyme, and liposomes can stably solubilize not only C₆₀ and C₇₀ , but also some C₆₀ derivatives in water. To improve the solubilities of fullerenes, specific methods have been developed for each solubilizing agent. Water-soluble C₆₀ and C₇₀ exhibit photoinduced cytotoxicity under near-ultraviolet irradiation, but not at wavelengths over 600 nm, which are the appropriate wavelengths for photodynamic therapy. However, dyad complexes of solubilized C₆₀ derivatives combined with light-harvesting antenna molecules improve the photoinduced cytotoxicities at wavelengths over 600 nm. Furthermore, controlling the fullerene and antenna molecule positions within the solubilizing agents affects the performance of the photosensitizer.

Use of Cyclodextrins in Anticancer Photodynamic Therapy Treatment

Photodynamic therapy (PDT) is mainly used to destroy cancerous cells; it combines the action of three components: a photoactivatable molecule or photosensitizer (PS), the light of an appropriate wavelength, and naturally occurring molecular oxygen. After light excitation of the PS, the excited PS then reacts with molecular oxygen to produce reactive oxygen species (ROS), leading to cellular damage. One of the drawbacks of PSs is their lack of solubility in water and body tissue fluids, thereby causing low bioavailability, drug-delivery efficiency, therapeutic efficacy, and ROS production. To improve the water-solubility and/or drug delivery of PSs, using cyclodextrins (CDs) is an interesting strategy. This review describes the in vitro or/and in vivo use of natural and derived CDs to improve antitumoral PDT efficiency in aqueous media. To achieve these goals, three types of binding modes of PSs with CDs are developed: non-covalent CD⁻PS inclusion complexes, covalent CD⁻PS conjugates, and CD⁻PS nanoassemblies. This review is divided into three parts: (1) non-covalent CD-PS inclusion complexes, covalent CD⁻PS conjugates, and CD⁻PS nanoassemblies, (2) incorporating CD⁻PS systems into hybrid nanoparticles (NPs) using up-converting or other types of NPs, and (3) CDs with fullerenes as PSs.

Improvement of Photodynamic Activity of Lipid-Membrane-Incorporated Fullerene Derivative by Combination with a Photo-Antenna Molecule

The weak absorbance of pristine C₆₀ , C₇₀ , and fullerene derivatives at wavelengths over 600 nm hampers the use of these molecules as photosensitizers (PSs) for photodynamic therapy (PDT). The coexistence of light-harvesting antenna molecules with a fullerene derivative in lipid membrane bilayers solved this issue. By controlling the location of the C₆₀ derivative in the lipid membrane, the liposomal dyad system for PDT improved the photodynamic activity via an efficient photoenergy transfer from antenna molecules to the fullerene derivative. The photodynamic activity was found to be much higher than those of dyad systems using pristine C₆₀ and C₇₀ .

Fullerenes in Biology and Medicine

Fullerenes and related carbon based derivatives have shown a growing relevance in biology and medicine, mainly due to the unique electronic and structural properties that make them excellent candidates for multiple functionalization. This review focuses on the most recent developments of fullerene derivatives for different biological applications.

Incorporation of large guest molecules into liposomes via chemical reactions in lipid membranes

The incorporation of hydrophobic guest molecules into lipid membranes by the exchange of the guest molecule from a cyclodextrin (CDx) complex to a liposome is limited to guest molecules that can be included in CDxs. To solve this problem, large guest molecules were incorporated into liposomes by chemical reactions of guest molecules in lipid membranes. Stable lipid-membrane-incorporated fullerene derivatives with large substituent(s) were prepared by Diels-Alder reactions in lipid membranes.

Lipid-membrane-incorporated arylboronate esters as agents for boron neutron capture therapy

An arylboronate ester bearing a methyl group at both of its ortho positions was stably incorporated into lipid membranes at high concentrations without hydrolysis.

Formation of lipid membrane-incorporated small π-molecules bearing hydrophilic groups

Lipid membrane-incorporated π-conjugated guest molecules (LMIGs) have been classified into four categories, including stable LMIGs, the precipitation or dissolution of some of the guest molecules from the LMIGs and the formation of small aggregates.