Cancer is one of the leading causes of death worldwide. Despite substantial progress in the understanding of tumor biology, and the appearance of new generations of targeted drugs and treatment techniques, the success achieved in this battle, with some notable exceptions, is still only moderate. Photodynamic therapy (PDT) is a successful but still underestimated therapeutic modality for treating many superficial cancers. In this paper, we focus on the extensive investigation of the monocationic chlorin photosensitizer (PS), considered here as a new photosensitizing agent for both antitumor and antimicrobial PDT. This monocationic chlorin PS (McChl) obtained from methylpheophorbide a (MPh) via a two-step procedure is well soluble in water in the physiological temperature range and forms stable complexes with passive carriers. McChl generates singlet oxygen with a good quantum yield in a lipid-like environment and binds mainly to low- and high-density lipoproteins in a vascular system. A comparison of the photodynamic activity of this agent with the activity of the well-established photosensitizer chlorin e6 (Chl e6) clearly indicates that McChl provides a much more efficient photoinactivation of malignant and microbial cells. The pilot PDT treatment of M1 sarcoma-bearing rats with this PS demonstrates its good potential for further preclinical investigations.

Now polymeric sorbents are used as basic environmental protection agents. They are used as filter elements for air and water purification. The application of stimulus-dependent polymers opens up new possibilities for the adsorption and desorption of different classes of substances. It was shown that the phase change behavior of dextran70-poly(N-isopropylacrylamide) copolymers at temperatures above 34-35 °C can be used for reversible adsorption/desorption of porphyrins. The interaction of meso-tetra(m-hydroxyphenyl)-porphine with the polymer at temperatures above the Lower Critical Solution Temperature leads to the binding of its molecule to the polymer matrix. The resulting complexes are stable. The results obtained suggest that the process of porphyrin-polymer complexation depends strongly on the physico-chemical properties of porphyrins.

Cancer and drug-resistant superinfections are common and serious problems afflicting millions worldwide. Photodynamic therapy (PDT) is a successful and clinically approved modality used for the management of many neoplastic and nonmalignant diseases. The combination of the light-activated molecules, so-called photosensitizers (PSs), with an appropriate carrier, is proved to enhance PDT efficacy both in vitro and in vivo. In this paper, we focus on the solvation of several potential chlorin PSs in the 1-octanol/phosphate saline buffer biphasic system, their interaction with non-ionic surfactant Tween 80 and photoinactivation of cancer cells. The chlorin conjugates containing d-galactose and l-arginine fragments are found to have a much stronger affinity towards a lipid-like environment compared to ionic chlorins and form molecular complexes with Tween 80 micelles in water with two modes of binding. The charged macrocyclic PSs are located in the periphery of surfactant micelles near hydrophilic head groups, whereas the d-galactose and l-arginine conjugates are deeper incorporated into the micelle structure occupying positions around the first carbon atoms of the hydrophobic surfactant residue. Our results indicate that both PSs have a pronounced affinity toward the lipid-like environment, leading to their preferential binding to low-density lipoproteins. This and the conjugation of chlorin e6 with the tumor-targeting molecules are found to enhance their accumulation in cancer cells and PDT efficacy.

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.

Сравнительный анализ структурных и кинетических характеристик комплексов фотосенсибилизатора мета-тетрагидроксифенилхлорина с различными типами / В. П. Зорин, Т. Е. Зорина, И. Е. Кравченко, И. В. Коблов // Физико-химическая биология как основа современной медицины : тез. докл. Междунар. науч. конф., посвящ. 75-летию со дня рождения проф. Е. В. Барковского, Минск, 21 мая 2021 г. / под ред. В. В. Хрусталёва, А. Д. Тагановича, Т. А. Хрусталёвой. – Минск, 2021. – С. 110-111.

Термочувствительные липосомальные носители фотосенсибилизаторов / Т. Е. Зорина, И. Е. Кравченко, Т. И. Ермилова, Т. В. Шман, В. П. Зорин // Физико-химическая биология как основа современной медицины : тез. докл. Междунар. науч. конф., посвящ. 75-летию со дня рождения проф. Е. В. Барковского, Минск, 21 мая 2021 г. / под ред. В. В. Хрусталёва, А. Д. Тагановича, Т. А. Хрусталёвой. – Минск, 2021. – С. 113-115.

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.

Thermosensitive polymer poly-N-isopropylacrylamide (PNIPAM) having a conformational transition in the interval of physiological temperatures was discussed last years as a novel drug delivery system. Chlorin e6 (Ce6) is a photosensitizer used in the photodynamic anticancer therapy. The comparative study of the encapsulation of Ce6 and its derivative, dimethylether of chlorine e6 (DME Ce6), into a water-soluble star-like PNIPAM-based copolymer to prevent the aggregation of a photosensitizer in the water medium is carried out. The photophysical properties of the copolymer/photosensitizer complexes as functions of the temperature in the region of the conformational transition of the polymer matrix have been studied and discussed. It is shown that Ce6 at low temperatures interacts weakly with the polymer phase. As a result, the absorption and fluorescence properties of Ce6 in aqueous and polymer solutions are practically identical. Fluorescence characteristics of Ce6 in a copolymer solution remain unchanged, when it is heated, which indicates the lack of a possibility for this sensitizer to bind in the bulk of the polymer phase. Following fluorescence data, all DME Ce6 molecules are bound with the polymer matrix, when a temperature is higher than the Lower Critical Solution Temperature (LCST) of the polymer. The formed complexes are quite stable. In the presence of serum proteins, the molecules of the photosensitizer remain associated for a long time with the polymer. At temperatures below LCST, DME Ce6 is not bound by the polymer. Moreover, the cooling of a solution of DME Ce6/polymer complexes leads to the rapid dissociation of photosensitizer molecules with subsequent aggregation or binding to biological structures in an aqueous medium. The obtained results show that the possibility of using the polymer PNIPAM as a temperature-dependent nanocarrier strongly depends on the properties of the loaded drug.

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 in vivo. 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 beta-CD (beta CDp) and carboxymethyl-beta-CD (CM beta CDp) monomers efficiently encapsulated mTHPC. We calculated the apparent binding constants between mTHPC and CD polymers (K = (6.3-8.8) x 10(6) M-1 and K = (1.2-1.7) x 10(6) M-1 for beta CDp and CM beta CDp, 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 in vivo study in preclinical models, which could be considered as an advanced smart system for mTHPC delivery.

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 by 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 the cells, is fundamental to achieve the desired effect on malignant tissues by 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.

We used the phenomenon of previously described photoinduced fluorescence quenching and fluorescence polarization to evaluate the transfer of meta -tetra(hydroxyphenyl)chlorin (m-THPC) from commercial high-drug load liposomes to plasma proteins and model membranes. Fluorescence quenching of m-THPC in liposomes by iodide indicates that part of m-THPC in PEGylated liposomes is localized in the PEG shell, while the rest is bound to the lipid bilayer. It was shown that the two molecule pools in the commercial PEGylated liposomal formulation Fospeg® condition the characteristics of the m-THPC release kinetics. A substantial percentage of m-THPC from Fospeg® is released much faster than from the conventional liposomal formulation Foslip®. Using the technique of resonance light scattering, it was shown that partial m-THPC aggregation is present in liposomes with very high drug loads, higher in PEGylated liposomes compared to conventional ones.

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.

Аминопроизводные хлорина е6 — эффективные фотосенсибилизаторы для фотодинамической терапии / Т. Е. Зорина [и др.] // Физико-химическая биология как основа современной медицины : тез. докл. Респ. конф. с междунар. участием, посвящ. 110-летию В.А. Бандарина, Минск, 24 мая 2019 г. : в 2 ч. / под ред. В. В. Хрусталёва, Т. А. Хрусталёвой. - Минск, 2019. - Ч. 1. - С. 113-114.

The photostability of complexes of the mTHPC photosensitizer with different types of cyclodextrins was studied. The photostability is a characteristic of the bond strength of the photosensitizer-carrier complex. The conclusions about the most appropriate type of cyclodextrin for photodynamic therapy were made. The optimal ratio of photosensitizer and carrier concentrations was determined.

—Confocal microscopy and colocalization analysis using Pearson correlation coefficients were used to show that esterified chlorin e 6 derivatives and their liposomal forms are mainly localized in the endoplasmic reticulum, Golgi complexes, cell mitochondria, and levels of their localization in lysosomes are low. Cellular uptake and accumulation kinetics of chlorin e 6 derivatives were strongly depended on the type of pharmacological formulation used for photosesitizers administration, while intracellular localization was independent on the formulation. Differences in the photodynamic activity and sensitization mechanisms for chlorin e 6 derivatives and their liposomal forms were shown when compared to those of chlorin e 6 photosensitizers in K562 cells. It is assumed that the observed differences in the mechanisms of cellular damage are to a greater extent due to specific photosensitizer localization.