Temoporfin-in-Cyclodextrin-in-Liposome-A New Approach for Anticancer Drug Delivery: The Optimization of Composition

Cyclodextrin-Based Arsenal for Anti-Cancer Treatments

Anti-cancer drugs are mostly limited in their use due to poor physicochemical and biopharmaceutical properties. Their lower solubility is the most common hurdle limiting their use upto their potential. In the recent years, the cyclodextrin (CD) complexation have emerged as existing approach to overcome the problem of poor solubility. CD-based nano-technological approaches are safe, stable and showed well in vivo tolerance and greater payload for encapsulation of hydrophobic drugs for the targeted delivery. They are generally chosen due to their ability to get self-assembled to form liposomes, nanoparticles, micelles and nano-sponges etc. This review paper describes a birds-eye view of the various CD-based nano-technological approaches applied for the delivery of anti-cancer moieties to the desired target such as CD based liposomes, niosomes, niosoponges, micelles, nanoparticles, monoclonal antibody, magnetic nanoparticles, small interfering RNA, nanorods, miscellaneous formulation of anti-cancer drugs containing CD. Moreover, the author also summarizes the various shortcomings of such a system and their way ahead.

Perturbation of Lipid Bilayers by Biomimetic Photoswitches Based on Cyclocurcumin

The use of photoswitches which may be activated by suitable electromagnetic radiation is an attractive alternative to conventional photodynamic therapy. Here, we report all-atom molecular dynamics simulation of a biomimetic photoswitch derived from cyclocurcumin and experiencing E/Z photoisomerization. In particular, we show that the two isomers interact persistently with a lipid bilayer modeling a cellular membrane. Furthermore, the interaction with the membrane is strongly dependent on the concentration, and a transition between ordered and disordered arrangements of the photoswitches is observed. We also confirm that the structural parameters of the bilayer are differently affected by the two isomers and hence can be modulated through photoswitching, offering interesting perspectives for future applications.

Hispolon Cyclodextrin Complexes and Their Inclusion in Liposomes for Enhanced Delivery in Melanoma Cell Lines

Hispolon, a phenolic pigment isolated from the mushroom species Phellinus linteus, has been investigated for anti-inflammatory, antioxidant, and anticancer properties; however, low solubility and poor bioavailability have limited its potential clinical translation. In this study, the inclusion complex of hispolon with Sulfobutylether-β-cyclodextrin (SBEβCD) was characterized, and the Hispolon-SBEβCD Complex (HSC) was included within the sterically stabilized liposomes (SL) to further investigate its anticancer activity against melanoma cell lines. The HSC-trapped-Liposome (HSC-SL) formulation was investigated for its sustained drug delivery and enhanced cytotoxicity. The inclusion complex in the solid=state was confirmed by a Job’s plot analysis, molecular modeling, differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), Proton nuclear magnetic resonance (NMR) spectroscopy, and scanning electron microscopy (SEM). The HSC-SL showed no appreciable deviation in size (<150 nm) and polydispersity index (<0.2) and improved drug encapsulation efficiency (>90%) as compared to control hispolon liposomes. Individually incorporated hispolon and SBEβCD in the liposomes (H-CD-SL) was not significant in loading the drug in the liposomes, compared to HSC-SL, as a substantial amount of free drug was separated during dialysis. The HSC-SL formulation showed a sustained release compared to hispolon liposomes (H-SLs) and Hispolon-SBEβCD liposomes (H-CD-SLs). The anticancer activity on melanoma cell lines (B16BL6) of HSC and HSC-SL was higher than in H-CD-SL and hispolon solution. These findings suggest that HSC inclusion in the HSC-SL liposomes stands out as a potential formulation approach for enhancing drug loading, encapsulation, and chemotherapeutic efficiency of hispolon and similar water insoluble drug molecules.

Royal Jelly Components Encapsulation in a Controlled Release System—Skin Functionality and Biochemical Activity for Skin Applications

Royal jelly is a yellowish-white substance with a gel texture that is secreted from the hypopharyngeal and mandibular glands of young worker bees. It consists mainly of water (50–56%), proteins (18%), carbohydrates (15%), lipids (3–6%), minerals (1.5%), and vitamins, and has many beneficial properties such as antimicrobial, anti-inflammatory, anticancer, antioxidant, antidiabetic, immunomodulatory, and anti-aging. Royal jelly has been used since ancient times in traditional medicine, cosmetics and as a functional food due to its high nutritional value. The main bioactive substances are royalactin, and 10-hydroxy-2-decenoic acid (10-HDA). Other important bioactive molecules with antioxidant and photoprotective skin activity are polyphenols. However, they present difficulties in extraction and in use as they are unstable physicochemically, and a higher temperature causes color change and component degradation. In the present study, a new encapsulation and delivery system consisting of liposomes and cyclodextrins incorporating royal jelly has been developed. The new delivery system aims to the elimination of the stability disadvantages of royal jelly’s sensitive component 10-HDA, but also to the controlled release of its ingredients and, more particularly, 10-HDA, for an enhanced bioactivity in cosmeceutical applications.

Recent Updates on Supramolecular-Based Drug Delivery - Macrocycles and Supramolecular Gels

Supramolecules-based drug delivery has attracted significant recent research attention as it could enhance drug solubility, retention time, targeting, and stimuli responsiveness. Among the different supramolecules and assemblies, the macrocycles and the supramolecular hydrogels are the two important categories investigated to a greater extent. Here, we provide the most recent advancements in these categories. Under macrocycles, reports on drug delivery by cyclodextrins, cucurbiturils, calixarenes/pillararenes, crown ethers and porphyrins are detailed. The second category discusses the supramolecular hydrogels of macrocycles/polymers and low molecular weight gelators. The updated information provided could be helpful to advance R & D in this vital area.

Parietin Cyclodextrin-Inclusion Complex as an Effective Formulation for Bacterial Photoinactivation

Multidrug resistance in pathogenic bacteria has become a significant public health concern. As an alternative therapeutic option, antimicrobial photodynamic therapy (aPDT) can successfully eradicate antibiotic-resistant bacteria with a lower probability of developing resistance or systemic toxicity commonly associated with the standard antibiotic treatment. Parietin (PTN), also termed physcion, a natural anthraquinone, is a promising photosensitizer somewhat underrepresented in aPDT because of its poor water solubility and potential to aggregate in the biological environment. This study investigated whether the complexation of PTN with (2-hydroxypropyl)-β-cyclodextrin (HP-β-CD) could increase its solubility, enhance its photophysical properties, and improve its phototoxicity against bacteria. At first, the solubilization behavior and complexation constant of the PTN/HP-β-CD inclusion complexes were evaluated by the phase solubility method. Then, the formation and physicochemical properties of PTN/HP-β-CD complexes were analyzed and confirmed in various ways. At the same time, the photodynamic activity was assessed by the uric acid method. The blue light-mediated photodegradation of PTN in its free and complexed forms were compared. Complexation of PTN increased the aqueous solubility 28-fold and the photostability compared to free PTN. PTN/HP-β-CD complexes reduce the bacterial viability of Staphylococcus saprophyticus and Escherichia coli by > 4.8 log and > 1.0 log after irradiation, respectively. Overall, the low solubility, aggregation potential, and photoinstability of PTN were overcome by its complexation in HP-β-CD, potentially opening up new opportunities for treating infections caused by multidrug-resistant bacteria.

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.

Modulation of Temoporfin Distribution in Blood by β-Cyclodextrin Nanoshuttles

Photodynamic therapy represents a more targeted and less invasive alternative cancer treatment to traditional modalities. Temoporfin, as with many photosensitizers, is given by injection into a vein, and its subsequent fate is largely determined by the binding to plasma proteins and interaction with endothelial and blood cells. Thus, it is essential to be able to control and to alter the biodistribution of temoporfin in blood. In the present study, we evaluated the effect of co-administration of temoporfin with randomly methylated β-CD (Me-β-CD) on the distribution of temoporfin in the main subpopulations of blood cells of healthy donors using absorbance spectrophotometry and flow cytometry. We showed that cell-bound temoporfin fraction in blood strongly depends on the concentration of Me-β-CD. In fact, the accumulation of temoporfin in white blood cells was more sensitive than that in red blood cells, due to the higher volume of membranous organelles in white blood cells. Finally, we demonstrated that Me-β-CD significantly increases cellular uptake of temoporfin cancer human Burkitt′s lymphoma Raji cells. The presence of Me-β-CD resulted in a spotted pattern of temoporfin distribution in the plasma membrane compartment. Our results clearly demonstrated that β-CDs derivatives provide new options to modulate temoporfin biodistribution in blood.

Nanocarriers for Biomedicine: From Lipid Formulations to Inorganic and Hybrid Nanoparticles

Encapsulation of cargoes in nanocontainers is widely used in different fields to solve the problems of their solubility, homogeneity, stability, protection from unwanted chemical and biological destructive effects, and functional activity improvement. This approach is of special importance in biomedicine, since this makes it possible to reduce the limitations of drug delivery related to the toxicity and side effects of therapeutics, their low bioavailability and biocompatibility. This review highlights current progress in the use of lipid systems to deliver active substances to the human body. Various lipid compositions modified with amphiphilic open-chain and macrocyclic compounds, peptide molecules and alternative target ligands are discussed. Liposome modification also evolves by creating new hybrid structures consisting of organic and inorganic parts. Such nanohybrid platforms include cerasomes, which are considered as alternative nanocarriers allowing to reduce inherent limitations of lipid nanoparticles. Compositions based on mesoporous silica are beginning to acquire no less relevance due to their unique features, such as advanced porous properties, well-proven drug delivery efficiency and their versatility for creating highly efficient nanomaterials. The types of silica nanoparticles, their efficacy in biomedical applications and hybrid inorganic-polymer platforms are the subject of discussion in this review, with current challenges emphasized.

Improvement of Butamben Anesthetic Efficacy by the Development of Deformable Liposomes Bearing the Drug as Cyclodextrin Complex

This work was aimed at enhancing butamben (BTB) anesthetic efficacy by the "drug-in cyclodextrin (CD)-in deformable liposomes" strategy. In the study, phase-solubility studies with natural (α-, β-, γ-) and derivative (hydroxypropyl-α-and β-, sulfobutylether-β, methyl-β) CDs evidenced the highest BTB affinity for βCD and its derivatives and indicated methyl-βCD (RAMEB) as the best carrier. Drug-RAMEB complexes were prepared by different techniques and were characterized for solid-state and dissolution properties. The best BTB-RAMEB product was chosen for entrapment in the aqueous core of deformable liposomes containing stearylamine, either alone or with sodium cholate, as edge activators. Double-loaded (DL) liposomes, bearing the lipophilic drug (0.5% w/v) in the bilayer and its hydrophilic RAMEB complex (0.5% w/v) in the aqueous core, were compared to single-loaded (SL) liposomes bearing 1% w/v plain drug in the bilayer. All vesicles showed homogeneous dimensions (i.e., below 300 nm), high deformability, and excellent entrapment efficiency. DL-liposomes were more effective than SL ones in limiting drug leakage (<5% vs. >10% after a 3 months storage at 4 °C). In vivo experiments in rabbits proved that all liposomal formulations significantly (p < 0.05) increased the intensity and duration of drug anesthetic action compared to its hydroalcoholic solution; however, DL liposomes were significantly (p < 0.05) more effective than SL ones in prolonging BTB anesthetic effect, owing to the presence of the drug-RAMEB complex in the vesicle core, acting as a reservoir. DL liposomes containing both edge activators were found to have the best performance.

Human small intestine cancer cell membrane-camouflaged quercetin-melanin for antibacterial and antitumor activity

E. coli has become an important factor that can lead to cancer because of its ability to cause diverse intestinal changes. Nano-polymer materials provide ideal drug delivery systems for preparing antibacterial and anti-cancer drugs because of their unique structure, easy modification, and high drug loading. The modified natural melanin has the potential to be an excellent nano-carrier. By improving the water-solubility and biocompatibility of the loaded natural drug quercetin, the antibacterial effect of quercetin can be fully played. Here, natural melanin was extracted from frozen squid to synthesize carrier polydopamine (PDA) nanoparticles, and the natural drug quercetin (Q) was modified on the surface of PDA by π-π bond and covalent bond action to produce melanin-quercetin (PDA-Q). We also developed human small intestinal cancer cells (HIC) membrane-camouflaged melanin-Quercetin (PDA-Q) nanoparticles as an anti-cancer platform in vivo. The potential bacteriostatic mechanism was likely driven by the penetration of PDA-Q in E. coli cells, damaging the integrity of the membranes of E. coli and inducing cell death. The mice wound experiment and bacteremia model experiment revealed that C@PDA-Q had a strong inhibitory effect on E. coli in vivo. In addition, the results of the in vitro tumor test also revealed that C@PDA-Q had strong anti-tumor activity against HIC cells of human small intestinal cancer, and the IC50 value was 12.3 ± 0.7 μg/ml, which was slightly better than that for cisplatin. As both melanin nanoparticles and HIC membrane are natural biomaterials, the synthesized C@PDA-Q nano-polymer material shows great potential for use in anti-cancer nano-drug loading.

Effect of stroma on the behavior of temoporfin-loaded lipid nanovesicles inside the stroma-rich head and neck carcinoma spheroids

Background

Despite the highly expected clinical application of nanoparticles (NPs), the translation of NPs from lab to the clinic has been relatively slow. Co-culture 3D spheroids account for the 3D arrangement of tumor cells and stromal components, e.g., cancer-associated fibroblasts (CAFs) and extracellular matrix, recapitulating microenvironment of head and neck squamous cell carcinoma (HNSCC). In the present study, we investigated how the stroma-rich tumor microenvironment affects the uptake, penetration, and photodynamic efficiency of three lipid-based nanoformulations of approved in EU photosensitizer temoporfin (mTHPC): Foslip^® (mTHPC in conventional liposomes), drug-in-cyclodextrin-in-liposomes (mTHPC-DCL) and extracellular vesicles (mTHPC-EVs).

Results

Collagen expression in co-culture stroma-rich 3D HNSCC spheroids correlates with the amount of CAFs (MeWo cells) in individual spheroid. The assessment of mTHPC loading demonstrated that Foslip^®, mTHPC-DCL and mTHPC-EVs encapsulated 0.05 × 10^− 15 g, 0.07 × 10^− 15 g, and 1.3 × 10^− 15 g of mTHPC per nanovesicle, respectively. The mid-penetration depth of mTHPC NPs in spheroids was 47.8 µm (Foslip^®), 87.8 µm (mTHPC-DCL), and 49.7 µm (mTHPC-EVs), irrespective of the percentage of stromal components. The cellular uptake of Foslip^® and mTHPC-DCL was significantly higher in stroma-rich co-culture spheroids and was increasing upon the addition of serum in the culture medium. Importantly, we observed no significant difference between PDT effect in monoculture and co-culture spheroids treated with lipid-based NPs. Overall, in all types of spheroids mTHPC-EVs demonstrated outstanding total cellular uptake and PDT efficiency comparable to other NPs.

Conclusions

The stromal microenvironment strongly affects the uptake of NPs, while the penetration and PDT efficacy are less sensitive to the presence of stromal components. mTHPC-EVs outperform other lipid nanovesicles due to the extremely high loading capacity. The results of the present study enlarge our understanding of how stroma components affect the delivery of NPs into the tumors.

Repurposing clinical drugs is a promising strategy to discover drugs against Zika virus infection

Zika virus (ZIKV) is an emerging pathogen associated with neurological complications, such as Guillain-Barré syndrome in adults and microcephaly in fetuses and newborns. This mosquito-borne flavivirus causes important social and sanitary problems owing to its rapid dissemination. However, the development of antivirals against ZIKV is lagging. Although various strategies have been used to study anti-ZIKV agents, approved drugs or vaccines for the treatment (or prevention) of ZIKV infections are currently unavailable. Repurposing clinically approved drugs could be an effective approach to quickly respond to an emergency outbreak of ZIKV infections. The well-established safety profiles and optimal dosage of these clinically approved drugs could provide an economical, safe, and efficacious approach to address ZIKV infections. This review focuses on the recent research and development of agents against ZIKV infection by repurposing clinical drugs. Their characteristics, targets, and potential use in anti-ZIKV therapy are presented. This review provides an update and some successful strategies in the search for anti-ZIKV agents are given.

Repositioning and investigational drugs for Zika virus infection treatment: a patent review

INTRODUCTION

Zika virus (ZIKV) is transmitted to humans throughout bites of Aedes mosquitoes. ZIKV infection may be asymptomatic in most cases, but it may cause fever, headache, muscle pain, and rash. Guillain-Barré syndrome also may be associated with the infection. Furthermore, the Pan American Health Organization informed 3,715 cases of the congenital ZIKV syndrome (CZS) in the Americas from 2015 - 2017, which may include microcephaly and other craniofacial deformities.

AREAS COVERED

This review identifies patent documents on repositioning for ZIKV infection treatment of already approved drugs or phases II/III investigated drugs for other diseases. Thirty-six patents were found reporting compounds with anti-ZIKV activity with application dates ranging from 2015 to 2019.

EXPERT OPINION

The main drugs claimed in patents were ribavirin, sofosbuvir, and alpha interferons. Preventing CZS is one of the most significant challenges in ZIKV infection. Therefore, repositioning sofosbuvir and niclosamide, that pose no danger for pregnant women, is a particular issue to be considered for clinical tests involving ZIKV disease. Given the substantial costs and developing time of new a drug, repositioning of old drugs is becoming an attractive alternative for diseases with neglected treatments.

Optical properties of photodynamic therapy drugs in different environments: the paradigmatic case of temoporfin

Computational tools have been used to study the photophysical and photochemical features of photosensitizers in photodynamic therapy (PDT) - a minimally invasive, less aggressive alternative for cancer treatment. PDT is mainly based on the activation of molecular oxygen through the action of a photoexcited sensitizer (photosensitizer). Temoporfin, widely known as mTHPC, is a second-generation photosensitizer, which produces the cytotoxic singlet oxygen when irradiated with visible light and hence destroys tumor cells. However, the bioavailability of the mostly hydrophobic photosensitizer, and hence its incorporation into cells, is fundamental to achieve the desired effect on malignant tissues via PDT. In this study, we focus on the optical properties of the temoporfin chromophore in different environments -in vacuo, in solution, encapsulated in drug delivery agents, namely cyclodextrin, and interacting with a lipid bilayer.

Cyclodextrin nanosponge as a temoporfin nanocarrier: Balancing between accumulation and penetration in 3D tumor spheroids

As the intertissue delivery of hydrophobic temoporfin (mTHPC) remains inefficient, we propose the use of cyclodextrin-based nanosponges as a smart, advanced system for improved mTHPC delivery. Recently, we demonstrated that cyclodextrins (CDs) allow mTHPC to penetrate into tumor spheroids via a nanoshuttle mechanism. However, the CD complexes were very sensitive to the dilution, thus limiting their translation invivo. Hypercrosslinked CD monomers in a three-dimensional network (namely, CD nanosponges), however, may form both inclusion and non-inclusion complexes with drug molecules, providing controlled release and prolonged exposure to the drug. In the present work, we demonstrate that epichlorohydrin-crosslinked CD nanosponges based on β-CD (βCDp) and carboxymethyl-β-CD (CMβCDp) monomers efficiently encapsulated mTHPC. We calculated the apparent binding constants between mTHPC and CD polymers (K=(6.3-8.8) × 10⁶M^-1 and K=(1.2-1.7) × 10⁶M^-1 for βCDp and CMβCDp, respectively) using fluorescence titration curve fitting. The encapsulation of mTHPC in a CD polymer matrix had slower photosensitizer (PS) release compared to monomer CD units, providing deep penetration of mTHPC in 3D tumor spheroids in a concentration-dependent manner. However, the improvement of mTHPC penetration in 3D human pharynx squamous cell carcinoma (FaDu) spheroids using CD polymers was strongly accompanied by the inhibition of PS cellular uptake, demonstrating the delicate balance between the accumulation and the penetration of PS in FaDu spheroids. In summary, mTHPC-loaded CD nanosponges are a strong candidate for further invivo study in preclinical models, which could be considered as an advanced smart system for mTHPC delivery.

A promising anticancer drug: a photosensitizer based on the porphyrin skeleton

Photodynamic therapy (PDT) is a minimally invasive combination of treatments that treat tumors and other diseases by using photosensitizers, light and oxygen to produce cytotoxic reactive oxygen species (ROS) inducing tumor cell apoptosis. Photosensitizers are the key part of PDT for clinical application and experimental research, and most of them are porphyrin compounds at present. Due to their unique affinity for tumor tissues, porphyrins are not only excellent photosensitizers, but also good carriers to transport other active drugs into tumor tissues, which can exert synergistic anticancer effects of PDT and chemotherapy. This article reviews the clinical development of porphyrin photosensitizers and the research status of porphyrin containing bioactive groups. Finally, future perspectives and the current challenges of photosensitizers based on the porphyrin skeleton are discussed.

Advantages of the combined use of cyclodextrins and nanocarriers in drug delivery: A review

Complexation with cyclodextrins (CDs) has been widely and successfully used in pharmaceutical field, mainly for enhancing solubility, stability and bioavailability of a variety of drugs. However, some important drawbacks, including rapid removal from the bloodstream after in vivo administration, or possible replacement, in biological media, of the entrapped drug moieties by other molecules with higher affinity for the CD cavity, can limit the CDs effectiveness as drug carriers. This review is focused on combined strategies simultaneously exploiting CD complexation, and loading of the complexed drug into various colloidal carriers (liposomes, niosomes, polymeric nanoparticles, lipid nanoparticles, nanoemulsions, micelles) which have been investigated as a possible means for circumventing the problems associated with both such carriers, when used separately, and join their relative benefits in a unique delivery system. Several examples of applications have been reported, to illustrate the possible advantages achievable by such a dual strategy, depending on the CD-nanocarrier combination, and mainly resulting in enhanced performance of the delivery system and improved biopharmaceutical properties and therapeutic efficacy of drugs. The major problems and/or drawbacks found in the development of such systems, as well as the (rare) case of failures in achieving the expected improvements have also been highlighted.

Cyclodextrin Based Nanoparticles for Drug Delivery and Theranostics

Colloidal nanoparticulate technology has been described in the literature as a versatile drug delivery system. But it possesses some inherent lacunae in their formulation. Cyclodextrins (CDs) have been extensively reported for the solubility enhancement of poorly water-soluble drugs. The CDs can cause intervention in aspects related to nanoparticles (NPs) that include improving drug loading in nano-system, improving stability, site-specific/targeted drug delivery, improving solubility profile and absorption of the drug in nanosystem with consequent improvement in bioavailability, with the possibility of controlled release, safety and efficacy. They find application in for simultaneous diagnosis and therapeutics for better treatment procedures. The current communication is focused on the application of CDs to overcome troubles in nanoparticulate formulation and enhancement of their performance. It also envisages the theranostic aspects of CDs.

Model of Ovarian Adenocarcinoma Spheroids for Assessing Photodynamic Cytotoxicity

The aim of the study was to compare the relevance of ovarian adenocarcinoma spheroids with that of a monolayer culture for assessing photodynamic effect of the tetrakis(4-benzyloxyphenyl)tetracyanoporphyrazine photosensitizer.

Materials and Methods

The work was performed on SKOV-3 human ovary adenocarcinoma cells grown in vitro in a monolayer culture and in the form of tumor spheroids obtained using culture plates with ultra-low attachment. We determined the photoinduced toxicity of porphyrazine on a monolayer culture using the MTT assay; the effect on the spheroids was tested by assessing the dynamics of their growth. Cellular uptake of porphyrazine was analyzed by confocal microscopy.

Results

Porphyrazine has a pronounced photodynamic effect on SKOV-3 cells. When exposed to light at a dose of 20 J/cm², the IC₅₀ value 24 h after exposure was 2.3 μM for SKOV-3 monolayer culture. For the spheroids, the effect manifested after a latency period: significant growth retardation of the treated spheroids appeared no sooner than 5 and 9 days after exposure. Notably, no decrease in the initial size of the treated spheroids was observed under any of the photodynamic regimes. The penetration depth of porphyrazine into spheroids was 50-100 μm during 24 h incubation.

Conclusion

The limited penetration of the photosensitizer into the body of spheroids and its predominant accumulation in the surface layers can be one of the key factors behind the significant differences in the photodynamic response between the surface and deep layers of a spheroid. For cells located close to the spheroid surface, the photodynamic effect is comparable to that for a monolayer culture, while in deeper layers, the cells remain viable and support/maintain the growth of the spheroid even under intense photo-exposure. The fact that the in vitro distribution is similar to the inhomogeneous accumulation of photosensitizers in tumors in vivo allows us to consider spheroids more relevant than a monolayer culture for studying photodynamic anti-tumor effects.

Porphyrinoid-Cyclodextrin Assemblies in Biomedical Research: An Update

Porphyrinoids, well-known cofactors in fundamental processes of life, have stimulated interest as synthetic models of natural systems and integral components of photodynamic therapy, but their utilization is compromised by self-aggregation in aqueous media. The capacity of cyclodextrins to include hydrophobic molecules in their cavity provides porphyrinoids with a protective environment against oxidation and the ability to disperse efficiently in biological fluids. Moreover, engineered cyclodextrin-porphyrinoid assemblies enhance the photodynamic abilities of porphyrinoids, can carry chemotherapeutics for synergistic modalities, and can be enriched with functions including cell recognition, tissue penetration, and imaging. This Perspective includes synthetic porphyrinoid-cyclodextrin models of proteins participating in fundamental processes, such as enzymatic catalysis, respiration, and electron transfer. In addition, since porphyrinoid-cyclodextrin systems comprise third generation photosensitizers, recent developments for their utilization in photomedicine, that is, multimodal therapy for cancer (e.g., PDT, PTT) and antimicrobial treatment, and eventually in biocompatible therapeutic or diagnostic platforms for next-generation nanomedicine and theranostics are discussed.

Matryoshka-Type Liposomes Offer the Improved Delivery of Temoporfin to Tumor Spheroids

The balance between the amount of drug delivered to tumor tissue and the homogeneity of its distribution is a challenge in the efficient delivery of photosensitizers (PSs) in photodynamic therapy (PDT) of cancer. To date, many efforts have been made using various nanomaterials to efficiently deliver temoporfin (mTHPC), one of the most potent photosensitizers. The present study aimed to develop double-loaded matryoshka-type hybrid nanoparticles encapsulating mTHPC/cyclodextrin inclusion complexes in mTHPC-loaded liposomes. This system was expected to improve the transport of mTHPC to target tissues and to strengthen its accumulation in the tumor tissue. Double-loaded hybrid nanoparticles (DL-DCL) were prepared, characterized, and tested in 2D and 3D in vitro models and in xenografted mice in vivo. Our studies indicated that DL-DCL provided deep penetration of mTHPC into the multicellular tumor spheroids via cyclodextrin nanoshuttles once the liposomes had been destabilized by serum proteins. Unexpectedly, we observed similar PDT efficiency in xenografted HT29 tumors for liposomal mTHPC formulation (Foslip^®) and DL-DCL.

Current state of the nanoscale delivery systems for temoporfin-based photodynamic therapy: Advanced delivery strategies

Enthusiasm for photodynamic therapy (PDT) as a promising technique to eradicate various cancers has increased exponentially in recent decades. The majority of clinically approved photosensitizers are hydrophobic in nature, thus, the effective delivery of photosensitizers at the targeted site is the main hurdle associated with PDT. Temoporfin (mTHPC, medicinal product name: Foscan®), is one of the most potent clinically approved photosensitizers, is not an exception. Successful temoporfin-PDT requires nanoscale delivery systems for selective delivery of photosensitizer. Over the last 25 years, the number of papers on nanoplatforms developed for mTHPC delivery such as conjugates, host-guest inclusion complexes, lipid-and polymer-based nanoparticles and carbon nanotubes is burgeoning. However, none of them appeared to be "ultimate". The present review offers the description of different challenges and achievements in nanoparticle-based mTHPC delivery focusing on the synergetic combination of various nano-platforms to improve temoporfin delivery at all stages of biodistribution. Furthermore, the association of different nanoparticles in one nanoplatform might be considered as an advanced strategy allowing the combination of several treatment modalities.

Complex systems that incorporate cyclodextrins to get materials for some specific applications

Cyclodextrins (CDs) are a family of biodegradable cyclic hydrocarbons composed of α-(1,4) linked glucopyranose subunits, the more common containing 6, 7 or 8 glucose units are named α, β and γ-cyclodextrins respectively. Since the discovery of CDs, they have attracted interest among scientists and the first studies were about the properties of the native compounds and in particular their use as catalysts of organic reactions. Characteristics features of different types of cyclodextrins stimulated investigation in different areas of research, due to its non-toxic and non-inmunogenic properties and also to the development of an improved industrial production. In this way, many materials with important properties have been developed. This mini-review will focus on chemical systems that use cyclodextrins, whatever linked covalently or mediated by the non covalent interactions, to build complex systems developed mainly during the last five years.

Effect of the Incorporation of Functionalized Cyclodextrins in the Liposomal Bilayer

Liposomes loaded with drug–cyclodextrin complexes are widely used as drug delivery systems, especially for species with low aqueous solubility and stability. Investigation of the intimate interactions of macrocycles with liposomes are essential for formulation of efficient and stable drug-in-cyclodextrin-in-liposome carriers. In this work, we reported the preparation of unilamellar vesicles of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) embedded with native β-cyclodextrin and two synthetic derivatives: heptakis(2,3,6-tri-O-methyl)-β-cyclodextrin (TMCD) and heptakis(2,3-di-O-acetyl)-β-cyclodextrin (DACD). We then studied the effect of these macrocycles on the liposomal size, membrane viscosity, and liposomal stability at different temperatures and concentrations. We observed that TMCD and DACD affected vesicle size and the change of size was related to CD concentration. Irrespective of its nature, the macrocycle established interactions with the phospholipidic head groups, preventing cyclodextrins to diffuse into the lipid bilayer, as confirmed by molecular dynamics simulations. Such supramolecular structuring improves liposome stability making these colloid systems promising carriers for biologically active compounds.