Phthalocyanine aggregates in the photodynamic therapy: dogmas, controversies, and future prospects

Exploring Si-phthalocyanines with different valency for PSMA-targeted photodynamic therapy: Synthesis and preclinical validation

Prostate cancer remains a significant health concern, with existing treatments often proving invasive or inadequate in preventing recurrence. This study explores the development and preclinical validation of silicon-phthalocyanine (SiPc)-based photosensitizers (PSs) targeted at prostate-specific membrane antigen (PSMA) for photodynamic therapy (PDT). Two PSMA-targeted SiPcs, monovalent and bivalent, were synthesized with axial conjugation through Si-O-C linkages to evaluate their efficacy and specificity. The bivalent SiPc-PQ-(PSMAi)2 demonstrated superior optical properties, reduced aggregation, and enhanced target specificity compared to the monovalent SiPc-PQ-PSMAi. Cellular and in vivo assays confirmed its high PSMA-specific uptake, potent photoinduced cytotoxicity mediated by reactive oxygen species, and significant tumor growth inhibition post-PDT. These findings underscore the potential of bivalent SiPc-PQ-(PSMAi)2 as an effective agent for targeted PDT, combining imaging and therapeutic capabilities for improved prostate cancer management. Further optimization and clinical evaluation could establish its role in theranostic strategies to enhance surgical outcomes and reduce recurrence.

Photodynamic Inactivation of Staphylococcus aureus and Biomolecules by Free and Encapsulated Indium(III) Phthalocyanines in PHB Nanoparticles: The Influence of the Position of the Coumarin Group

Antimicrobial photodynamic therapy (APDT) is a promising alternative to inactivating resistant microorganisms. Metallic phthalocyanines (Pc) substituted with coumarin groups exhibit favorable photophysical properties for APDT; however, their hydrophobicity limits administration. This study investigates indium(III) Pc substituted with 7-oxy-3-(3',4',5'-trimethoxyphenyl)coumarin at nonperipheral (3nInOAc) and peripheral (4nInOAc) positions, both in their free form and encapsulated in polyhydroxybutyrate nanoparticles, for the photodynamic inactivation of methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-susceptible Staphylococcus aureus (MSSA) bacteria. The photodynamic activity was also assessed through the photooxidation of tryptophan and bovine serum albumin. Theoretical calculations and molecular docking were performed to corroborate the experimental results, investigating the influence of molecular structure on the photodynamic and antimicrobial performance of Pc-loaded nanoparticles as well as their nanoparticulate properties. Overall, both free and encapsulated Pc were capable of photooxidizing biomolecules and exhibited moderate antimicrobial activity, with 4nInOAc demonstrating superior efficacy, achieving an average reduction of 2 logs (99%) in MSSA and MRSA colonies.

Role of Secondary Structure and Time-Dependent Binding on Disruption of Phthalocyanine Aggregates by Guanine-Rich Nucleic Acids

Phthalocyanines are versatile photodynamic therapy agents whose biological activity depends on their aggregation state, which is expected to be influenced by binding to biomolecules. Here, guanine-rich nucleic acid binding of a water-soluble cationic, regiopure C4h zinc phthalocyanine bearing four triethylene glycol methyl ether and four N-methyl-4-pyridinium substituents (1) is reported. In contrast to double-stranded DNA, guanine systems GpG, (GG)10, poly(G) and quadruplex DNA are shown to effectively disrupt phthalocyanine aggregates in buffered solution. This process is accompanied by evolution of the Q-band absorbance and enhanced emission. Increasing the sequence length from GpG to (GG)10 increases the binding and confirms the importance of multiple binding interactions. Enhanced binding in the presence of KCl suggests the importance of nucleobase hydrogen-bonded mosaics in phthalocyanine binding. Notably, the (GT)10 sequence is even more effective than quadruplex and pure guanine systems at disrupting the aggregates of 1. Significant time-dependent binding of 1 with poly(G) reveals biexponential binding over minutes and hours, which is linked to local conformations of poly(G) that accommodate monomers of 1 over time. The study highlights the ability of biomacromolecules to disrupt phthalocyanines aggregates over time, which is an important consideration when rationalizing photoactivity of photosensitizers in-vivo.

Pivotal Role of the Intracellular Microenvironment in the High Photodynamic Activity of Cationic Phthalocyanines

To investigate the influence of phthalocyanine aggregation on their photodynamic activity, a series of six cationic water-soluble zinc(II) phthalocyanines bearing from four to sixteen 4-((diethylmethylammonium)methyl)phenoxy substituents was synthesized. Depending on their structure, the phthalocyanines have different aggregation behaviors in phosphate buffer solutions ranging from fully assembled to monomeric states. Remarkably, independent of aggregation in buffer, very high photodynamic efficiencies against the tumor cell lines MCF-7 and MDA-MB-231 in the nanomolar range were found for all investigated phthalocyanine, and the IC50(light) varied from 27 to 358 nM (3.5 J/cm2, 660 nm) with IC50(dark)/IC50(light) ratios up to ∼3700. This is due to the intracellular disassembly of aggregated phthalocyanines with the formation of monomeric photoactive forms, as demonstrated by fluorescence microscopy. Indeed, the interaction of aggregated phthalocyanines with serum proteins in a buffer resulted in the disassembly of nonluminescent aggregate species with the release of photoactive monomers bound to protein macromolecules.

Biopharmaceutical drug delivery and phototherapy using protein crystals

Biopharmaceutical drugs, including proteins, peptides, and antibodies, are renowned for their high specificity and efficacy, fundamentally transforming disease treatment paradigms. However, their structural complexity presents challenges for their formulation and delivery. Protein crystals, characterized by high purity, high stability and a porous structure for biopharmaceutical drug encapsulation, providing a potential avenue for formulating and delivering biopharmaceutical drugs. There is increasing interest in engineering protein crystals to delivery biopharmaceutical drugs for biomedical applications. This review summarizes the recent advances in biopharmaceutical drug delivery and phototherapy using protein crystals. First, we evaluate the advantages of using protein crystals for biopharmaceutical drugs delivery. Next, we outline the strategies for in vitro and in vivo crystallization to prepare protein crystals. Importantly, the review highlights the advanced applications of protein crystals in biopharmaceutical drug delivery, tumor phototherapy, and other optical fields. Finally, it provides insights into future perspectives of biopharmaceutical drug delivery using protein crystals. This comprehensive review aims to provide effective insights into design of protein crystals to simplify biopharmaceutical drug delivery and improve disease treatment.

Visualizing Active Sites in Electrospun Photoactive Membranes via Fluorescence Lifetime Imaging

Interest in antibacterial nanomaterials has surged in recent years, driven by the rise in antibiotic resistance among microbes. However, their practical application remains limited because many crucial properties have yet to be thoroughly investigated. In this study, we have developed novel nanofibrous membranes based on hydrophilic polyacrylonitrile (PAN) or hydrophobic polycaprolactone (PCL) with embedded hydrophilic or hydrophobic zinc(II)phthalocyanines (ZnPcs) as photosensitizers and investigated their water disinfection properties. Several key characteristics were evaluated to link the activity of the material and composition/structure. As demonstrated by reflectance UV/Vis spectroscopy, the aggregation states of dyes within the polymer support vary significantly. We have proposed and validated the use of fluorescence lifetime imaging (FLIM) for visualizing "active sites" in the membranes. The results of this study provide useful insights for the engineering of photoactive nanomaterials with tailor-made properties and highlight the crucial role of the nature of polymeric support in modulating the material's activity.

Structural Decoration of Porphyrin/Phthalocyanine Photovoltaic Materials

Porphyrin/phthalocyanine compounds with fascinating molecular structures have attracted widespread attention in the field of solar cells in recent years. In this review, we focus on the pivotal role of porphyrin and phthalocyanine compounds in enhancing the efficiency of solar cells. The review seamlessly integrates the intricate molecular structures of porphyrins and phthalocyanines with their proficiency in absorbing visible light and facilitating electron transfer, key processes in converting sunlight into electricity. By delving into the nuances of intramolecular regulation, aggregated states, and surface/interface structure manipulation, it elucidates how various levels of molecular modifications enhance solar cell efficiency through improved charge transfer, stability, and overall performance. This comprehensive exploration provides a detailed understanding of the complex relationship between molecular design and solar cell performance, discussing current advancements and potential future applications of these molecules in solar energy technology.

VII Congress of Russian Biophysicists-2023, Krasnodar, Russia

This special issue of Biophysical Reviews contains the materials presented at the VII Congress of Biophysicists of Russia, held from 17 to 23 April in Krasnodar. We believe that we have managed to prepare a selection of articles that well reflects the current state of biophysical science in Russia and its place in the world science. The VII Russian Congress on Biophysics was held in Krasnodar in April 2023, continuing the tradition of the series of biophysics conferences held every 4 years. The congress discussed physical principles and mechanisms of biological processes occurring at different life levels-from molecular to cellular and population levels. The results of fundamental and applied research in molecular biophysics, cell biophysics, and biophysics of complex systems were presented at plenary, sectional, and poster sessions. The works in the field of medical biophysics and neurobiology were especially widely presented. The structure and dynamics of biopolymers and fundamental mechanisms underlying the effects of physicochemical factors on biological systems, membrane, and transport processes were actively discussed. Much attention was paid to new experimental methods of biophysical research, methods of bioinformatics, computer, and mathematical modeling as necessary tools of the research at all levels of living systems. Along with fundamental problems of studying biophysical mechanisms of regulation of processes at the molecular, subcellular, and cellular levels, much attention was paid to applied research in the field of biotechnology and environmental monitoring. The Congress has formed the National Committee of Russian biophysicists.