Current states and future views in photodynamic therapy

A novel porphyrin-based theranostic agent activated by cysteine over-expressed in cancer cells shows promise for tumour-targeted monitoring and phototherapy

l-Cysteine (Cys) is a tumor-related biomarker. The photo- and Cys-activatable theranostic agent 4 was designed and synthesized based on 5,10,15,20-tetrakis(4-hydroxyphenyl)porphyrin (3). Compound 4 exhibited negligible fluorescence and photosensitizing activity in the absence of Cys. However, when activated by Cys, 3 was released, resulting in fluorescence and photosensitization. Moreover, upon irradiation with 660 nm light, 4 displayed selective and effective fluorescence and photo-cytotoxicity exclusively against cancer cells, such as HeLa and A549 cells, which express high levels of Cys. This wavelength of light falls within the phototherapeutic window.

Understanding the Photophysical Properties of Pd and Pt Transition-Metal Isocorroles: A Theoretical Investigation

The main photophysical properties of recently synthesized Pd- and Pt-isocorroles, characterized and proposed as potential photosensitizers in photodynamic therapy, have been investigated and rationalized using density functional theory and its time-dependent formulation. Both the 5 and 10-(2-pyrrolyl)-5,10,15-tris(4-methylphenyl) isomers have been considered. In addition to determining the minimum energy structures of the ground and excited states, we have calculated the excitation energies, spin-orbit coupling constants, nonradiative intersystem crossing rate constants and two photons cross section. Also, the type I PDT mechanisms have been considered. Results show that the photoactivity of both Pd and Pt complexes mainly depends on their singlet-triplet energy gap, which is necessary to promote the O23 Σ g - → 1 Δ g ${{}^{{\rm { 3}}}{{\rm { \Sigma{}}}}_{{\rm { g}}}^{{\rm { -}}}\to {}^{1}{\Delta }_{g}}$ excitation. The study of the photophysical properties of the free ligands indicates that this trend is common for both the free and Pt- and Pd-isocorroles. The production of superoxide ions (O2 .(-)) is possible only for the 10-(2-pyrrolyl)-5,10,15-tris(4-methylphenyl) isomers.

Photodynamic therapy photosensitizers and photoactivated chemotherapeutics exhibit distinct bioenergetic profiles to impact ATP metabolism

Energy is essential for all life, and mammalian cells generate and store energy in the form of ATP by mitochondrial (oxidative phosphorylation) and non-mitochondrial (glycolysis) metabolism. These processes can now be evaluated by extracellular flux analysis (EFA), which has proven to be an indispensable tool in cell biology, providing previously inaccessible information regarding the bioenergetic landscape of cell lines, complex tissues, and in vivo models. Recently, EFA demonstrated its utility as a screening tool in drug development, both by providing insights into small molecule-organelle interactions, and by revealing the peripheral and potentially undesired off-target effects small molecules have within cells. Surprisingly, technologies to quantify cellular bioenergetics have not been systematically applied in phototherapy development, leaving open several questions about how the mechanism of action of a compound can impact essential cellular functions. Here, we utilized the Seahorse analyzer to address this question for photosensitizers (PSs) for photodynamic therapy (PDT) and contrast these systems to molecules that photo-release a ligand and thus act as photocages or photoactivated chemotherapeutics (PACT), intending to understand the influence these two classes of compounds have on cellular bioenergetics. EFA results show that acute treatment of A549 lung adenocarcinoma cells with PDT agents induces a quiescent bioenergetic response as a result of mitochondrial respiration shutdown. The loss of oxidative phosphorylation is followed by disruption of glycolysis, which occurs after an initial increase in glycolytic respiration is unable to compensate for the interruption of the electron transport chain (ETC). In contrast, the PACT agents tested had little impact on cellular respiration, and the minor inhibition of these metabolic processes was not related to the mechanism of action, as reflected by a lack of correlation with photoejection efficiency. Notably, a system capable of both generating 1O2 and photo-releasing a ligand exhibited the dominant profile of a PDT agent and induced the quiescent bioenergetic state, indicating potential implications on cellular bioenergetics for so-called dual-action agents. These findings are presented with the aim to provide the necessary groundwork for expanding the application and utility of EFA to phototherapeutics and to highlight the role of metabolic alterations in PDT.

Moderately Heavy Atom-Substituted BODIPY Photosensitizer with Mitochondrial Targeting Ability for Imaging-Guided Photodynamic Therapy

Advanced photodynamic therapy requires photosensitizers with targeting, diagnostic, and therapeutic properties. To fulfill this multifunctionality, we report the synthesis of two triphenylphosphonium (TPP)-functionalized boron-dipyrromethene (BODIPY) dyes, TPPB-H and TPPB-Br, which incorporate a hydrogen atom and dibrominated vinyl moiety at the 6-position of the BODIPY core, respectively. The heavy-atom effect of the moderately heavy bromine atoms allowed TPPB-Br to achieve a proper balance between the toxic singlet oxygen (1O2) production and fluorescence efficiencies. In this dye, the bromine atom-induced stimulation of the singlet-to-triplet intersystem crossing dynamics resulted in an approximately 45-fold increase in the 1O2 quantum yield with respect to that of the nonbrominated counterpart (0.0059 and 0.28 for TPPB-H and TPPB-Br, respectively). This increase was accompanied only a 2-fold reduction in the fluorescence quantum yield (0.54 and 0.22 for TPPB-H and TPPB-Br, respectively). During multicolor confocal laser scanning microscopy observations conducted using two carcinomas, MCF-7 and HeLa, both BODIPY dyes exhibited high targeting specificity toward cancer cell mitochondria owing to the TPP cation functionalization. The two dyes also showed the feasibility of fluorescence cell imaging; however, only the dibrominated BODIPY TPPB-Br manifested pronounced photocytotoxicity with half-maximal inhibitory concentrations of 0.12 and 0.77 μM obtained for MCF-7 and HeLa cells, respectively. These findings demonstrate the potential applicability of TPPB-Br as an imaging-guided photodynamic therapy agent with mitochondrial specificity.

Efficient Delivering of a Photodynamic Therapy Drug into Cellular Membranes Rationalized by Molecular Dynamics

Photodynamic therapy (PDT) represents a most attractive therapeutic strategy to reduce side-effects of chemotherapy and improve the global quality of life of patients. Yet, many PDT drugs suffer from poor bioavailability and cellular intake, and thus, drug-delivering strategies are mandatory. In this article, we rationalize the behavior of a temoporfin-based PDT drug, commercialized under the name of Foscan, complexed by two β-cyclodextrin units, acting as drug carriers, in the presence of a lipid bilayer. Our all-atom simulations have unequivocally shown the internalization of the drug-delivering complex and suggest its possible spontaneous dissociation in the lipid bilayer core. The factors favoring penetration and dissociation have also been analyzed, together with membrane perturbation due to the interaction with the drug carrier complex. Our results confirm the suitability of this encapsulation strategy for PDT and rationalize the experimental results concerning its efficacy.

Advances in smart nanotechnology-supported photodynamic therapy for cancer

Cancer has emerged as a formidable challenge in the 21st century, impacting society, public health, and the economy. Conventional cancer treatments often exhibit limited efficacy and considerable side effects, particularly in managing the advanced stages of the disease. Photodynamic therapy (PDT), a contemporary non-invasive therapeutic approach, employs photosensitizers (PS) in conjunction with precise light wavelengths to selectively target diseased tissues, inducing the generation of reactive oxygen species and ultimately leading to cancer cell apoptosis. In contrast to conventional therapies, PDT presents a lower incidence of side effects and greater precision in targeting. The integration of intelligent nanotechnology into PDT has markedly improved its effectiveness, as evidenced by the remarkable synergistic antitumor effects observed with the utilization of multifunctional nanoplatforms in conjunction with PDT. This paper provides a concise overview of the principles underlying PS and PDT, while also delving into the utilization of nanomaterial-based PDT in the context of cancer treatment.

Photodynamic therapy using hybrid nanoparticles comprising of upconversion nanoparticles and chlorin e6-bearing pullulan

With its minimal invasiveness, photodynamic therapy (PDT) is considered one of the most elegant modalities in cancer treatment. In this study, a facile hybrid nanoparticle was developed, composed of upconversion nanoparticles and chlorin e6-bearing pullulan, which can serve as a photosensitizer activated by a near-infrared red laser. Cell death induction in cancer cells was achieved through energy transfer from the near-infrared red laser emitted by the upconversion nanoparticles to chlorin e6. The therapeutic efficacy of our hybrid system surpassed that of the clinically available photosensitizer, Photofrin, and hybrid liposomes comprising upconversion nanoparticles and chlorin e6 were employed as control. Accumulation of our system in tumor tissue in tumor xenograft mice was primarily achieved through the enhanced permeability and retention (EPR) effect. The administered hybrids were excreted from each organ within 21 days after administration, minimizing the risk of undesirable side effects. Notably, our system exhibited 400 times higher PDT activity in tumor-bearing mice compared to the control groups. It also effectively inhibited metastasis.

Combined use of 5-ALA-induced protoporphyrin IX and chlorin e6 for fluorescence diagnostics and photodynamic therapy of skin tumors

Different types of photosensitizers (PSs) have different dynamics and intensities of accumulation, depending on the type of tumor or different areas within the same tumor. This determines the effectiveness of fluorescence diagnostics and photodynamic therapy (PDT). This paper studies the processes of 5-aminolevulinic acid (5-ALA)-induced protoporphyrin IX (PpIX) and chlorin e6 (Ce6) accumulation in the central and border zones of a tumor after combined administration of two PSs into the patient's body. Fluorescence diagnostic methods have shown that sublingual administration of 5-ALA leads to the more intense accumulation of PpIX in a tumor compared to oral administration. Differences have been identified in the dynamics of 5-ALA-induced PpIX and Ce6 accumulation in the central and border zones of the tumor, as well as normal tissues. Ce6 accumulates mainly in the central zone of the tumor while PpIX accumulates in the border zone of the tumor. All patients with combined PDT experienced complete therapeutic pathomorphosis and relapse-free observation.

Water-Soluble Rotaxane-Type Porphyrin Dyes as a Highly Membrane-Permeable and Durable Photosensitizer Suitable for Photodynamic Therapy

Porphyrins have emerged as highly effective photosensitizers in the field of photodynamic therapy (PDT) because of their high singlet oxygen generation efficiency. However, most porphyrin derivatives do not have adequate water solubility and cell membrane permeability suitable for use in PDT. In addition, they frequently suffer from low durability under photoirradiation. Here, we propose rotaxane-type photosensitizers, in which a porphyrin axle is irreversibly encapsulated within cyclodextrins (CDs), to overcome the drawbacks of porphyrins for PDT. The rotaxane-type photosensitizers were synthesized in high yields by employing a cooperative capture strategy. The CD derivatives worked as a transparent shell to impart a porphyrin axle not only with water solubility but also with photostability. These rotaxanes showed higher cell membrane permeability and photoinduced cytotoxic abilities than talaporfin sodium, presently used as a clinical photosensitizer. The rotaxane-based photosensitizer could have potential for being ideal PDT drugs.

Improving the Photodynamic Activity of Water-Soluble Porphyrin-Polysaccharide Complexes by Folic Acid Modification

Studies have shown that folate receptors are highly expressed in various cancer cells. Here, we synthesized folic acid-conjugated pullulan (FAPL) as a solubilizing agent to improve the photodynamic activity of porphyrin derivative-polysaccharide complexes. The porphyrin derivative-FAPL complex exhibited long-term stability in an aqueous solution, attributed to the folic acid modification. Furthermore, in vitro and in vivo experiments highlighted the enhanced photodynamic activity of the porphyrin derivative-FAPL complex toward 4T1 breast-cancer cells, compared with the activities of the porphyrin derivative-pullulan complex and Photofrin. This enhanced activity is attributed to the improvement of intracellular uptake by the folate receptor.

Nanozyme Decorated Metal-Organic Framework Nanosheet for Enhanced Photodynamic Therapy Against Hypoxic Tumor

Introduction

Photodynamic therapy (PDT) has attracted increasing attention in the clinical treatment of epidermal and luminal tumors. However, the PDT efficacy in practice is severely impeded by tumor hypoxia and the adverse factors associated with hydrophobic photosensitizers (PSs), including low delivery capacity, poor photoactivity and limited ROS diffusion. In this study, Pt nanozymes decorated two-dimensional (2D) porphyrin metal-organic framework (MOF) nanosheets (PMOF@HA) were fabricated and investigated to conquer the obstacles of PDT against hypoxic tumors.

Materials and Methods

PMOF@HA was synthesized by the coordination of transition metal iron (Zr4+) and PS (TCPP), in situ generation of Pt nanozyme and surface modification with hyaluronic acid (HA). The abilities of hypoxic relief and ROS generation were evaluated by detecting the changes of O2 and 1O2 concentration. The cellular uptake was investigated using flow cytometry and confocal laser scanning microscopy. The SMMC-7721 cells and the subcutaneous tumor-bearing mice were used to demonstrate the PDT efficacy of PMOF@HA in vitro and in vivo, respectively.

Results

Benefiting from the 2D structure and inherent properties of MOF materials, the prepared PMOF@HA could not only serve as nano-PS with high PS loading but also ensure the rational distance between PS molecules to avoid aggregation-induced quenching, enhance the photosensitive activity and promote the rapid diffusion of generated radical oxide species (ROS). Meanwhile, Pt nanozymes with catalase-like activity effectively catalyzed intratumoral overproduced H2O2 into O2 to alleviate tumor hypoxia. Additionally, PMOF@HA, with the help of externally coated HA, significantly improved the stability and increased the cell uptake by CD44 overexpressed tumor cells to strengthen O2 self-supply and PDT efficacy.

Conclusion

This study provided a new strategy of integrating 2D porphyrin MOF nanosheets with nanozymes to conquer the obstacles of PDT against hypoxic tumors.

Synthesis and Photodynamic Activities of Pyridine- or Pyridinium-Substituted Aza-BODIPY Photosensitizers

In this work, various novel pyridinyl- and pyridinium-modified Aza-BODIPY PSs were designed and constructed based on monoiodo Aza-BODIPY PSs (BDP-4 and BDP-15) in an attempt to construct "structure-inherent organelles-targeted" PSs to endow potential organelle-targeting ability. Pyridinyl PSs displayed potent photodynamic efficacy, and monorigidified PSs were very effective. The monorigidified PS 20 with meta-pyridinyl moiety displayed the most potent photoactivity and negligible dark toxicity with a favorable dark/phototoxicity ratio (>4800). To our surprise, monorigidified PS with meta-pyridinyl moiety (e.g., 20) was lipid droplet-targeted. 20 showed good cellular uptake and intracellular ROS generation compared with BDP-15. The preliminary cell death process exploration indicated that 20 resulted in lipid peroxidation and induced cell death through an iron-independent ferroptosis-like cell death pathway. In vivo antitumor efficacy experiments manifested that 20 significantly inhibited tumor growth and outperformed BDP-15 and Ce6 even under a single low-dose light irradiation (30 J/cm2).

A novel photosensitizer based on hypocrellin B activated by cysteine over-expressed in cancer cells

L-Cysteine (Cys)-activatable photosensitizer 3 was designed and synthesized based on hypocrellin B (1). Cys is a novel tumor-associated biomarker. 3 exhibited negligible photosensitizing ability without Cys. However, when 1 was released from 3 by reaction with Cys, the photosensitizing activity was restored. Furthermore, 3 showed selective and effective photo-cytotoxicity against only cancer cells such as HeLa and A549 cells that highly express Cys when irradiated with 660 nm light, which is inside the phototherapeutic window.

TiO2-ZnPc nanoparticles functionalized with folic acid as a target photosensitizer for photodynamic therapy against glioblastoma cells

The use of TiO2 as a photosensitizer in photodynamic therapy is limited due to TiO2 generates reactive oxygen species only under UV irradiation. The TiO2 surface has been modified with different functional groups to achieve activation at longer wavelengths (visible light). This work reports the synthesis, characterization, and biological toxicity assay of TiO2 nanoparticles functionalized with folic acid and combined with a zinc phthalocyanine to obtain a nano-photosensitizer for its application in photodynamic therapy for glioblastoma cancer treatment. The nano-photosensitizer was prepared using the sol-gel method. Folic acid and zinc phthalocyanine were added during the hydrolysis and condensation of titanium butoxide, which was the TiO2 precursor. The samples obtained were characterized by several microscopy and spectroscopy techniques. An in vitro toxicity test was performed using the MTT assay and the C6 cellular line. The results of the characterization showed that the structure of the nanoparticles corresponds mainly to the anatase phase. Successful functionalization with folic acid and an excellent combination with phthalocyanine was also achieved. Both folic acid-functionalized TiO2 and phthalocyanine-functionalized TiO2 had no cytotoxic effect on C6 cells (even at high concentrations) in comparison to Cis-Pt, which was very toxic to C6 cells. The materials behaved similarly to the control (untreated cells). The cell viability and light microscopy images suggest that both materials could be considered biocompatible and mildly phototoxic in these cells when activated by light.

Naphtho[1,8-ef]isoindole-7,8,10(9H)-trione as Novel Theranostic Agents for Photodynamic Therapy and Multi-Subcellular Organelles Localization

A series of naphtho[1,8-ef]isoindole-7,8,10(9H)-trione derivatives as novel theranostic agents for photodynamic therapy and multi-subcellular organelles localization were designed and synthesized. Most of them possess moderate fluorescence quantum yield and long wavelength absorption simultaneously, which made them possible for dual effects of imaging and therapy. Notably, compounds 7 b and 7 d exhibited significant light-toxicity but slight dark-toxicity. Confocal fluorescence microscopy experiments demonstrated that compound 7 b can locate and image in special multi-subcellular organelles. All the research results implied that naphtho[1,8-ef] isoindole-7,8,10(9H)-trione derivatives can be applied as a new series of theranostic agents with the characteristics of photodynamic therapy and multi-subcellular organelles imaging.

Chalcogen atom effect on the intersystem crossing kinetic constant of oxygen- and sulfur disubstituted heteroporphyrins

The modulation of the photophysical properties of di-substituted porphyrin rings upon the oxygen and sulfur-for-nitrogen replacement has been investigated at density functional theory (DFT) and its time-dependent formulation (TDDFT). The considered properties range from structural behaviors and excitation energies to spin-orbit coupling (SOC) and nonradiative intersystem kinetic constants. Results show that the SOC strongly increase upon chalcogen substitution and, accordingly, the computed nonradiative kinetic constant also indicate an efficient singlet-triplet intersystem crossing in the sulfur containing macrocycle. The presented results indicate an alternative way to properly modulate the porphyrin's crucial properties for their use in photodynamic therapy, without resorting to the use of heavy atoms.

Graphene-Based Photodynamic Therapy and Overcoming Cancer Resistance Mechanisms: A Comprehensive Review

Photodynamic therapy (PDT) is a non-invasive therapy that has made significant progress in treating different diseases, including cancer, by utilizing new nanotechnology products such as graphene and its derivatives. Graphene-based materials have large surface area and photothermal effects thereby making them suitable candidates for PDT or photo-active drug carriers. The remarkable photophysical properties of graphene derivates facilitate the efficient generation of reactive oxygen species (ROS) upon light irradiation, which destroys cancer cells. Surface functionalization of graphene and its materials can also enhance their biocompatibility and anticancer activity. The paper delves into the distinct roles played by graphene-based materials in PDT such as photosensitizers (PS) and drug carriers while at the same time considers how these materials could be used to circumvent cancer resistance. This will provide readers with an extensive discussion of various pathways contributing to PDT inefficiency. Consequently, this comprehensive review underscores the vital roles that graphene and its derivatives may play in emerging PDT strategies for cancer treatment and other medical purposes. With a better comprehension of the current state of research and the existing challenges, the integration of graphene-based materials in PDT holds great promise for developing targeted, effective, and personalized cancer treatments.

Phyto-Photodynamic Therapy of Prostate Cancer Cells Mediated by Yemenite 'Etrog' Leave Extracts

Cancer therapy, from malignant tumor inhibition to cellular eradication treatment, remains a challenge, especially regarding reduced side effects and low energy consumption during treatment. Hence, phytochemicals as cytotoxic sensitizers or photosensitizers deserve special attention. The dark and photo-response of Yemenite 'Etrog' leaf extracts applied to prostate PC3 cancer cells is reported here. An XTT cell viability assay along with light microscope observations revealed pronounced cytotoxic activity of the extract for long exposure times of 72 h upon concentrations of 175 μg/mL and 87.5 μg/mL, while phototoxic effect was obtained even at low concentration of 10.93 μg/mL and a short introduction period of 1.5 h. For the longest time incubation of 72 h and for the highest extract concentration of 175 μg/mL, relative cell survival decreased by up to 60% (below the IC50). In combined phyto-photodynamic therapy, a reduction of 63% compared to unirradiated controls was obtained. The concentration of extract in cells versus the accumulation time was inversely related to fluorescence emission intensity readings. Extracellular ROS production was also shown. Based on an ATR-FTIR analysis of the powdered leaves and their liquid ethanolic extract, biochemical fingerprints of both polar and non-polar phyto-constituents were identified, thereby suggesting their implementation as phyto-medicine and phyto-photomedicine.

On the antibacterial photodynamic inactivation mechanism of Emodin and Dermocybin natural photosensitizers: A theoretical investigation

A DFT and TDDFT study has been carried out on monomeric anthraquinones Emodin and Dermocybin (Em, Derm) recently proposed as natural antibacterial photosensitizers able to act also against gram-negative microbes. The computational study has been performed considering the relative amount of neutral and ionic forms of each compound in water, with the variation of pH. The occurrence of both Type I and Type II photoreactions has been explored computing the absorption properties of each species, the spin-orbit coupling constants (SOC), the vertical ionization potentials and the vertical electron affinities. The most plausible deactivation channels leading to the population of excited triplet states have been proposed. Our data indicate Emodin as more active than Dermocybin in antimicrobial photodynamic therapy throughout the Type II mechanism. Our data support a dual TypeI/II activity of the monomeric anthraquinones Emodin and Dermccybin in water, in all the considered protonation states.

Photoinactivation of microorganisms using bacteriochlorins as photosensitizers

In recent years, some microorganisms have shown resistance to conventional treatments. Considering this increase in resistant pathogens, treatment alternatives are needed to promote greater treatment efficiency. In this sense, antimicrobial photodynamic therapy (aPDT) has been an alternative treatment. This technique uses a photosensitizer that is activated by light with a specific wavelength producing reactive species, leading to the death of pathogenic microorganisms. In this study, bacteriochlorophyll derivatives such as bacteriochlorin metoxi (Bchl-M) and bacteriochlorin trizma (Bchl-T) obtained from purple bacterium (Rhodopseudomonas faecalis), were evaluated as photosensitizers in the aPDT. Photodynamic inactivation (PDI) of the microorganisms Staphylococcus aureus, Micrococcus luteus, Candida albicans and Pseudomonas aeruginosa was investigated with both bacteriochlorins (Bchl-M and Bchl-T) at different concentrations (1, 15 and 30 µM for S. aureus; 1, 15, 30, 45, 60 and 75 µM for M. luteus; 30, 60, 90, 105, 120 and 150 µM for C. albicans; and 200 µM for P. aeruginosa) and different doses of light (20 and 30 J/cm2 for S. aureus and M. luteus; 30 and 45 J/cm2 for C. albicans; and 45 J/cm2 for P. aeruginosa) to inactivate them. Both photosensitizers showed good activation against S. aureus and for M. luteus, we observed the inactivation of these microorganisms at approximately 3 log, showing to be a good photosensitizers for these microorganisms.

Triphenylphosphonium-functionalized dimeric BODIPY-based nanoparticles for mitochondria-targeting photodynamic therapy

The dimerization of boron dipyrromethene (BODIPY) moieties is an appealing molecular design approach for developing heavy-atom-free triplet photosensitizers (PSs). However, BODIPY dimer-based PSs generally lack target specificity, which limits their clinical use for photodynamic therapy. This study reports the synthesis of two mitochondria-targeting triphenylphosphonium (TPP)-functionalized meso-β directly linked BODIPY dimers (BTPP and BeTPP). Both BODIPY dimers exhibited solvent-polarity-dependent singlet oxygen (1O2) quantum yields, with maximum values of 0.84 and 0.55 for BTPP and BeTPP, respectively, in tetrahydrofuran. The compact orthogonal geometry of the BODIPY dimers facilitated the generation of triplet excited states via photoinduced charge separation (CS) and subsequent spin-orbit charge-transfer intersystem crossing (SOCT-ISC) processes and their rates were dependent on the energetic configuration between the frontier molecular orbitals of the two BODIPY subunits. The as-synthesized compounds were amphiphilic and hence formed stable nanoparticles (∼36 nm in diameter) in aqueous solutions, with a zeta potential of ∼33 mV beneficial for mitochondrial targeting. In vitro experiments with MCF-7 and HeLa cancer cells indicated the effective localization of BTPP and BeTPP within cancer-cell mitochondria. Under light irradiation, BTPP and BeTPP exhibited robust photo-induced therapeutic effects in both cell lines, with half-maximal inhibitory concentration (IC50) values of ∼30 and ∼55 nM, respectively.

A silyl porphyrin derivative conjugated with 6-deoxy-6-sulfo-α-d-glucopyranose functions as an efficient photosensitizer for photodynamic therapy

We synthesized a new silyl porphyrin derivative conjugated with 6-deoxy-6-sulfo-α-d-glucopyranose (SGlc). Conjugation with SGlc improved A549 cellular uptake without significant changes in the photophysical and photochemical properties and subcellular localization. This improved cellular uptake led to enhanced photodynamic activity. Furthermore, conjugation with SGlc suppressed dark toxicity. These advantages were not observed for a conjugate with a glucose molecule. These results indicated that the conjugation with SGlc is a promising strategy for enhancing photodynamic efficacy.

Aptamer-Based Targeting of Cancer: A Powerful Tool for Diagnostic and Therapeutic Aims

Cancer is known as one of the most significant causes of death worldwide, and, in spite of novel therapeutic methods, continues to cause a considerable number of deaths. Targeted molecular diagnosis and therapy using aptamers with high affinity have become popular techniques for pathological angiogenesis and cancer therapy scientists. In this paper, several aptamer-based diagnostic and therapeutic techniques such as aptamer-nanomaterial conjugation, aptamer-drug conjugation (physically or covalently), and biosensors, which have been successfully designed for biomarkers, were critically reviewed. The results demonstrated that aptamers can potentially be incorporated with targeted delivery systems and biosensors for the detection of biomarkers expressed by cancer cells. Aptamer-based therapeutic and diagnostic methods, representing the main field of medical sciences, possess high potential for use in cancer therapy, pathological angiogenesis, and improvement of community health. The clinical use of aptamers is limited due to target impurities, inaccuracy in the systematic evolution of ligands via exponential enrichment (SELEX)stage process, and in vitro synthesis, making them unreliable and leading to lower selectivity for in vivo targets. Moreover, size, behavior, probable toxicity, low distribution, and the unpredictable behavior of nanomaterials in in vivo media make their usage in clinical assays critical. This review is helpful for the implementation of aptamer-based therapies which are effective and applicable for clinical use and the design of future studies.

Hydrophilic Biocompatible Fluorescent Organic Nanoparticles as Nanocarriers for Biosourced Photosensitizers for Photodynamic Therapy

Most photosensitizers of interest for photodynamic therapy-especially porphyrinoids and chlorins-are hydrophobic. To circumvent this difficulty, the use of nanocarriers is an attractive strategy. In this perspective, we have developed highly water-soluble and biocompatible fluorescent organic nanoparticles (FONPs) made from citric acid and diethyltriamine which are then activated by ethlynene diamine as nanoplatforms for efficient photosensitizers (PSs). Purpurin 18 (Pp18) was selected as a biosourced chlorin photosensitizer combining the efficient single oxygen generation ability and suitable absorption in the biological spectral window. The simple reaction of activated FONPs with Pp18, which contains a reactive anhydride ring, yielded nanoparticles containing both Pp18 and Cp6 derivatives. These functionalized nanoparticles combine solubility in water, high singlet oxygen generation quantum yield in aqueous media (0.72) and absorption both in the near UV region (FONPS) and in the visible region (Soret band approximately 420 nm as well as Q bands at 500 nm, 560 nm, 660 nm and 710 nm). The functionalized nanoparticles retain the blue fluorescence of FONPs when excited in the near UV region but also show deep-red or NIR fluorescence when excited in the visible absorption bands of the PSs (typically at 520 nm, 660 nm or 710 nm). Moreover, these nanoparticles behave as efficient photosensitizers inducing colorectal cancer cell (HCT116 and HT-29 cell lines) death upon illumination at 650 nm. Half maximal inhibitory concentration (IC50) values down to, respectively, 0.04 and 0.13 nmol/mL were observed showing the potential of FONPs[Cp6] for the PDT treatment of cancer. In conclusion, we have shown that these novel biocompatible nanoparticles, which can be elaborated from biosourced components, both show deep-red emission upon excitation in the red region and are able to produce singlet oxygen with high efficiency in aqueous environments. Moreover, they show high PDT efficiency on colorectal cancer cells upon excitation in the deep red region. As such, these functional organic nanoparticles hold promise both for PDT treatment and theranostics.

Glycosylated Porphyrin Derivatives for Sonodynamic Therapy: ROS Generation and Cytotoxicity Studies in Breast Cancer Cells

Sonodynamic therapy (SDT) is a promising alternative to photodynamic therapy for achieving site-specific cytotoxic therapy. Porphyrin derivative molecules have been reported extensively in photodynamic therapy. We have previously shown that the glycosylation of porphyrin-based sonosensitizers can enhance their cellular uptake. However, the sonodynamic potential of these water-soluble glycosylated porphyrins has not been investigated. In this study, we characterized the sonodynamic response of two water-soluble glycosylated porphyrin derivatives. Ultrasound (US) exposure was performed (1 MHz frequency, intensities of 0.05-1.1 W/cm2) for 0-3 min in continuous mode. Reactive oxygen species (ROS) generation was quantified via ultraviolet-visible (UV-vis) spectrophotometry. MTT assay was used to quantify cytotoxicity caused by sonodynamic effects from these derivatives in the human mammary carcinoma (SUM-159) cell line in vitro. ROS generation from the porphyrin derivatives was demonstrated at a concentration of 15 μM. No significant cytotoxic effects were observed with the sonosensitizer alone or US exposure alone over the tested range of intensities and duration. The free base porphyrin derivative caused 60-70% cell death, whereas the zinc-porphyrin derivative with Zn metal conjugation caused nearly 50% cytotoxicity when exposed at 0.6 W/cm2 intensity for 3 min. These studies demonstrate the potential of anticancer SDT with soluble glycosylated porphyrins.

Electronic spectroscopy of gemcitabine and derivatives for possible dual-action photodynamic therapy applications

In this paper, we explore the molecular basis of combining photodynamic therapy (PDT), a light-triggered targeted anticancer therapy, with the traditional chemotherapeutic properties of the well-known cytotoxic agent gemcitabine. A photosensitizer prerequisite is significant absorption of biocompatible light in the visible/near IR range, ideally between 600 and 1000 nm. We use highly accurate multiconfigurational CASSCF/MS-CASPT2/MM and TD-DFT methodologies to determine the absorption properties of a series of gemcitabine derivatives with the goal of red-shifting the UV absorption band toward the visible region and facilitating triplet state population. The choice of the substitutions and, thus, the rational design is based on important biochemical criteria and on derivatives whose synthesis is reported in the literature. The modifications tackled in this paper consist of: (i) substitution of the oxygen atom at O2 position with heavier atoms (O → S and O → Se) to red shift the absorption band and increase the spin-orbit coupling, (ii) addition of a lipophilic chain at the N7 position to enhance transport into cancer cells and slow down gemcitabine metabolism, and (iii) attachment of aromatic systems at C5 position to enhance red shift further. Results indicate that the combination of these three chemical modifications markedly shifts the absorption spectrum toward the 500 nm region and beyond and drastically increases spin-orbit coupling values, two key PDT requirements. The obtained theoretical predictions encourage biological studies to further develop this anticancer approach.

Novel chlorin e6-based conjugates of tyrosine kinase inhibitors: Synthesis and photobiological evaluation as potent photosensitizers for photodynamic therapy

Since tyrosine kinase inhibitor (TKI) could reverse ABCG2-mediated drug-resistance, novel chlorin e6-based conjugates of Dasatinib and Imatinib as photosensitizer (PS) were designed and synthesized. The results demonstrated that conjugate 10b showed strongest phototoxicity against HepG2 and B16-F10 cells, which was more phototoxic than chlorin e6 and Talaporfin. It could reduce efflux of intracellular PS by inhibiting ABCG2 in HepG2 cells, and localize in mitochondria, lysosomes, golgi and ER, resulting in higher cell apoptosis rate and ROS production than Talaporfin. Moreover, it could induce cell autophagy and block cell cycle in S phase, and significantly inhibit tumor growth and prolong survival time on BALB/c nude mice bearing HepG2 xenograft tumor to a greater extent than chlorin e6. Consequently, compound 10b could be applied as a promising candidate PS due to its good water-solubility and stability, low drug-resistance, high quantum yield of 1O2 and excellent antitumor efficacy in vitro and in vivo.

Management of Long-Segment Barrett's Esophagus

Background: Gastroesophageal reflux disease is a common gastrointestinal disorder with one of its most feared complications being Barrett's esophagus (BE). Currently, most of the recommendations of BE management are driven by the level of dysplasia. However, the length of BE might also be related to the risk of dysplasia/malignant transformation. We aimed to determine the appropriate management of BE based on its length. Materials and Methods: A systematic literature review was conducted with searches made on PubMed, Embase, and Cochrane databases. Long-segment BE (LSBE) was defined as 3 cm or longer and short-segment BE (SSBE) as under 3 cm. Studies evaluating the behavior and management of SSBE and/or LSBE were included for analysis. Results: LSBE have greater risk of dysplasia or progression to esophageal adenocarcinoma compared to SSBE. Despite this greater risk, LSBE and SSBE are currently managed similarly based on the presence and degree of dysplasia. Endoscopic and ablative techniques may have higher level of success and less complications in SSBE, compared to LSBE. Decreasing time interval between surveillance may be a viable option for managing LSBE. Conclusions: Although many algorithms of monitoring and treatment of BE remain the same regardless of segment length, current evidence suggests that more aggressive management for LSBE might be needed due to its higher risk of malignant progression.

Synthesis and biological evaluation of bi-modal BODIPY-conjugated Hoechst applicable for Auger-electron and photodynamic cancer therapy

Current therapeutic approaches to cancer are not fully effective, and so development of more effective treatment is needed. Auger-electron therapy and photodynamic therapy have attracted marked attentions as a promising strategy in cancer treatment. In this study, we synthesized [125I]BH-2/BH-2, which comprised Hoechst and 2,6-diiodo-substituted BODIPY, and evaluated its usefulness as a bi-modal agent for Auger-electron/photodynamic therapy by comparison with the previously reported compound [125I]BH/BH. [125I]BH-2 was obtained at a 13% radiochemical yield. [125I]BH-2 showed similar uptake into the nucleus to [125I]BH, suggesting that Hoechst can function as a nuclear localization tag. HeLa cell viabilities were reduced in both cells exposed to [125I]BH-2 and [125I]BH. γ-H2AX foci in HeLa cells exposed to [125I]BH-2 or [125I]BH were increased in a dose-dependent manner, indicating that DNA double-strand breaks may have occurred. No significant difference was observed between [125I]BH-2 and [125I]BH at these investigations. For PDT application, BH-2 showed a higher singlet oxygen quantum yield (ΦΔ) and caused superior photo-induced cytotoxicity in HeLa cells compared with BH. These results suggest that bi-modal [125I]BH-2/BH-2 can cause anti-tumor effects with Auger-electron and photodynamic therapy.

Photo- and Sono-Active Food Colorants Inactivating Bacteria

Food colorants are commonly used as excipients in pharmaceutical and nutraceutical fields, but they have a wide range of other potential applications, for instance, as cytotoxic drugs or mediators of physical antimicrobial treatments. The photodynamic antibacterial activity of several edible food colorants is reported here, including E127, E129, E124, E122, E133, and E150a, alongside Rhein, a natural lipophilic antibacterial and anticancer compound found in medicinal plants. Minimal inhibitory concentration (MIC) values for S. aureus and E. coli showed that E127 and Rhein were effective against both bacteria, while other colorants exhibited low activity against E. coli. In some cases, dark pre-incubation of the colorants with Gram-positive S. aureus increased their photodynamic activity. Adding Rhein to E127 increased the photodynamic activity of the latter in a supportive mode. Optional sensing mechanism pathways of combined E127/Rhein action were suggested. The antibacterial activity of the studied colorants can be ranged as follows: E127/Rhein >> E127 >> E150a > E122 > E124 >> E129 ≈ E133. E127 was also found to exhibit photodynamic properties. Short ultrasonic treatment before illumination caused intensification of E127 photodynamic activity against E. coli when applied alone and especially in combination with Rhein. Food colorants exhibiting photo- and sonodynamic properties may have good potential in food preservation.

Preparation of a Water-Soluble Glycopolymer Bearing Porphyrin Skeletons and Its Biological Properties

A known tetraphenyl porphyrin (TPP) having an amino functional group [5-(4-aminophenyl)-10,15,20-(triphenyl)porphyrin] was converted into the corresponding monomer by means of condensation with acryloyl chloride. Simple radical polymerization of the porphyrin monomer and a glycosyl monomer in the presence of acrylamide as a regulator monomer in order to avoid steric interference gave a water-soluble glycopolymer bearing porphyrin moieties. Spectroscopic analyses suggested incorporation of porphyrin moieties in the glycopolymer. The physical properties of the water-soluble glycopolymer bearing porphyrin moieties were examined in aqueous media, and the results also indicated the incorporation of TPP moieties in the polymer. Uptake of the polymer into HeLa cells was observed, and the cytotoxicity of the polymer was confirmed by microscopic analyses. The glycopolymer bearing porphyrin moieties is promising not only for photodynamic therapy but also as an anti-cancer reagent.

Exploration of NIR Squaraine Contrast Agents Containing Various Heterocycles: Synthesis, Optical Properties and Applications

Squaraine dye is a popular class of contrast near-infrared (NIR) dyes. Squaraine dyes have shown the ability to be modified with various heterocycles. The indole moiety is the most notable heterocycle incorporated in squaraine dyes. A tremendous amount of work has gone into developing indole-based squaraine dyes and determining their applications. The optical properties of squaraine dyes containing an indole moiety facilitate high quantum yields and molar absorptivity, but the absorbance maxima is capped near 700 nm. This is the major limitation of indole-based squaraine dyes. In comparison, other heterocycles with larger conjugated systems such as quinoline and perimidine have demonstrated promising optical properties and immense potential for modifications, albeit with limited development. Quinoline- and perimidine-based squaraine dyes have molar extinction coefficients over 100,000 M-1 cm-1 and absorbances over 800 nm. This report will look at indole-, quinoline-, and perimidine-based squaraine dyes. Due to the sheer number of reported dyes, the search for indole-based squaraine dyes has been limited to reports from the past five years (2018-2023). For quinoline- and perimidine-based squaraine dyes, a holistic search was performed to analyze the optical properties and applications, due to the abovementioned limitation. This report will evaluate the three different classes of squaraines: indole-, quinoline-, and perimidine-based, to evaluate their optical properties and applications, with the goal of encouraging the exploration of other heterocycles for use in squaraine dyes.

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.

Locally Administered Photodynamic Therapy for Cancer Using Nano-Adhesive Photosensitizer

Photodynamic therapy (PDT) is a great potential anti-tumor therapy owing to its non-invasiveness and high spatiotemporal selectivity. However, systemically administered photosensitizers diffuse in the skin and the eyes for a long duration, which cause phototoxicity to bright light and sunlight. Therefore, following PDT, patients must avoid exposure of to light and sunlight to avoid this phototoxicity. In this study, we have developed a locally administered PDT using nano-adhesive porphyrin with polycations consisting of quaternary ammonium salt groups (aHP) as a photosensitizer. The aHP, approximately 3.0 nm in diameter, adhered the negatively charged cell membrane via electrostatic interaction. The aHP localized to the endosome via cell adhesion and induced apoptosis upon 635 nm light irradiation. On being administered subcutaneously on the tumor, 30% of the injected aHP remained in the administered sites. However, low-molecular-weight hematoporphyrin dihydrochloride (HP) disappeared due to rapid diffusion. PDT with locally administered aHP showed a higher anti-tumor effect after light irradiation at 635 nm for three days compared to low-molecular-weight HP. Intraperitoneal administration of HP caused severe phototoxicity upon irradiation with ultraviolet A at 10 J cm-2, whereas aHP did not cause phototoxicity because its diffusion into the skin could be suppressed, probably due to the high-molecular weight of aHP. Therefore, locally administered PDT with aHP is a potential PDT having high therapeutic efficacy without phototoxicity.

Formylation as a Chemical Tool to Modulate the Performance of Photosensitizers Based on Boron Dipyrromethene Dimers

Heavy-atom-free photosensitizers are envisioned as the next generation of photoactive molecules for photo-theragnosis. In this approach, and after suitable irradiation, a single molecular scaffold is able to visualize and kill tumour cells by fluorescence signalling and photodynamic therapy (PDT), respectively, with minimal side effects. In this regard, BODIPY-based orthogonal dimers have irrupted as suitable candidates for this aim. Herein, we analyse the photophysical properties of a set of formyl-functionalized BODIPY dimers to ascertain their suitability as fluorescent photosensitizers. The conducted computationally aided spectroscopic study determined that the fluorescence/singlet oxygen generation dual performance of these valuable BODIPY dimers not only depends on the BODIPY-BODIPY linkage and the steric hindrance around it, but also can be modulated by proper formyl functionalization at specific chromophoric positions. Thus, we propose regioselective formylation as an effective tool to modulate such a delicate photonic balance in BODIPY-based dimeric photosensitizers. The taming of the excited-state dynamics, in particular intramolecular charge transfer as the key underlying process mediating fluorescence deactivation vs. intersystem crossing increasing, could serve to increase fluorescence for brighter bioimaging, enhance the generation of singlet oxygen for killing activity, or balance both for photo-theragnosis.

RAFT Synthesis and Characterization of Poly(Butyl-co-2-(N,N-Dimethylamino)Ethyl Acrylates)-block-Poly(Polyethylene Glycol Monomethyl Ether Acrylate) as a Photosensitizer Carrier for Photodynamic Therapy

Polymer micelles are promising drug delivery systems for highly hydrophobic photosensitizers in photodynamic therapy (PDT) applications. We previously developed pH-responsive polymer micelles consisting of poly(styrene-co-2-(N,N-dimethylamino)ethyl acrylate)-block-poly(polyethylene glycol monomethyl ether acrylate) (P(St-co-DMAEA)-b-PPEGA) for zinc phthalocyanine (ZnPc) delivery. In this study, poly(butyl-co-2-(N,N-dimethylamino)ethyl acrylates)-block-poly(polyethylene glycol monomethyl ether acrylate) (P(BA-co-DMAEA)-b-PPEGA) was synthesized via reversible addition and fragmentation chain transfer (RAFT) polymerization to explore the role of neutral hydrophobic units in photosensitizer delivery. The composition of DMAEA units in P(BA-co-DMAEA) was adjusted to 0.46, which is comparable to that of P(St-co-DMAEA)-b-PPEGA. The size distribution of the P(BA-co-DMAEA)-b-PPEGA micelles changed when the pH decreased from 7.4 to 5.0, indicating their pH-responsive ability. The photosensitizers, 5,10,15,20-tetrakis(pentafluorophenyl)chlorin (TFPC), 5,10,15,20-tetrakis(pentafluorophenyl)porphyrin (TFPP), protoporphyrin IX (PPIX), and ZnPc were examined as payloads for the P(BA-co-DMAEA)-b-PPEGA micelles. The encapsulation efficiency depended on the nature of the photosensitizer. TFPC-loaded P(BA-co-DMAEA)-b-PPEGA micelles exhibited higher photocytotoxicity than free TFPC in the MNNG-induced mutant of the rat murine RGM-1 gastric epithelial cell line (RGK-1), indicating their superiority for photosensitizer delivery. ZnPc-loaded P(BA-co-DMAEA)-b-PPEGA micelles also exhibited superior photocytotoxicity compared to free ZnPc. However, their photocytotoxicity was lower than that of P(St-co-DMAEA)-b-PPEGA. Therefore, neutral hydrophobic units, as well as pH-responsive units, must be designed for the encapsulation of photosensitizers.

Dual-Drug-Loaded Topical Delivery of Photodynamically Active Lipid-Based Formulation for Combination Therapy of Cutaneous Melanoma

Topical administration of anti-cancer drugs along with photodynamically active molecules is a non-invasive approach, which stands to be a promising modality for treating aggressive cutaneous melanomas with the added advantage of high patient compliance. However, the efficiency of delivering drugs topically is limited by several factors, such as penetration of the drug across skin layers at the tumor site and limited light penetrability. In this study, curcumin, an active anti-cancer agent, and chlorin e6, a photoactivable molecule, were encapsulated into lipidic nanoparticles that produced reactive oxygen species (ROS) when activated at 665 nm by near-infrared (NIR) light. The optimized lipidic nanoparticle containing curcumin and chlorin e6 exhibited a particle size of less than 100 nm. The entrapment efficiency for both molecules was found to be 81%. The therapeutic efficacy of the developed formulation was tested on B16F10 and A431 cell lines via cytotoxicity evaluation, combination index, cellular uptake, nuclear staining, DNA fragmentation, ROS generation, apoptosis, and cell cycle assays under NIR irradiation (665 nm). Co-delivering curcumin and chlorin e6 exhibited higher cellular uptake, better cancer growth inhibition, and pronounced apoptotic events compared to the formulation having the free drug alone. The study results depicted that topical application of this ROS-generating dual-drug-loaded lipidic nanoparticles incorporated in SEPINEO gel achieved better permeation (80 ± 2.45%) across the skin, and exhibited the improved skin retention and a synergistic effect as well. The present work introduces photo-triggered ROS-generating dual-drug-based lipidic nanoparticles, which are simple and efficient to develop and exhibit synergistic therapeutic effects against cutaneous melanoma.

Sulphur- and Selenium-for-Oxygen Replacement as a Strategy to Obtain Dual Type I/Type II Photosensitizers for Photodynamic Therapy

The effect on the photophysical properties of sulfur- and selenium-for-oxygen replacement in the skeleton of the oxo-4-dimethylaminonaphthalimide molecule (DMNP) has been explored at the density functional (DFT) level of theory. Structural parameters, excitation energies, singlet–triplet energy gaps (ΔES-T), and spin–orbit coupling constants (SOC) have been computed. The determined SOCs indicate an enhanced probability of intersystem crossing (ISC) in both the thio- and seleno-derivatives (SDMNP and SeDMNP, respectively) and, consequently, an enhancement of the singlet oxygen quantum yields. Inspection of Type I reactions reveals that the electron transfer mechanisms leading to the generation of superoxide is feasible for all the compounds, suggesting a dual Type I/Type II activity.

Recent advances in Metal-Organic Frameworks as nanocarriers for triggered release of anticancer drugs: Brief history, biomedical applications, challenges and future perspective

Metal-Organic Frameworks (MOFs) have emerged as a promising biomedical material due to its unique features such as high surface area, pore volume, variable pore size, flexible functional groups, and excellent efficiency for drug loading. In this review, we explored the use of novel and smart metal organic frameworks as drug delivery vehicles to discover a safer and more controlled mode of drug release aiming to minimize their side effects. Here, we systematically discussed the background of MOFs following a thorough review on structural and physical properties of MOFs, their synthesis techniques, and the important characteristics to establish a strong foundation for future research. Furthermore, the current status on the potential applications of MOF-based stimuli-responsive drug delivery systems, including pH-, ion-, temperature-, light-, and multiple responsive systems for the delivery of anticancer drugs has also been presented. Lastly, we discuss the prospects and challenges in implementation of MOF-based materials in the drug delivery. Therefore, this review will help researchers working in the relevant fields to enhance their understanding of MOFs for encapsulation of various drugs as well as their stimuli responsive mechanism.

Imaging of mitochondria/lysosomes in live cells and C. elegans

Two rhodamine-phenothiazine conjugates, RP1 and RP2, were synthesized, and their photophysical properties, subcellular localization, and photocytotoxicity were investigated. We observed robust localization of RP1 in mitochondria and dual localization in mitochondria and lysosomes with RP2 in live cells. Live cell imaging with these probes allowed us to track the dynamics of mitochondria and lysosomes during ROS-induced mitochondrial damage and the subsequent lysosomal digestion of the damaged mitochondria. The fluorophores also demonstrated preferential accumulation in cancer cells compared to normal cells and had strong photo-cytotoxicity. However, no cytotoxicity was observed in the dark. The mitochondrial staining and light-induced ROS production were not limited to mammalian cell lines, but were also observed in the animal model C. elegans. The study demonstrated the potential applications of these probes in visualizing the mitochondria-lysosome cross-talk after ROS production and for photodynamic therapy.

Recent Advances in Green Metallic Nanoparticles for Enhanced Drug Delivery in Photodynamic Therapy: A Therapeutic Approach

Globally, cancer is one of the leading causes of death among men and women, it is characterized by the unregulated proliferation of tumor cells. Some of the common risk factors associated with cancer development include the consistent exposure of body cells to carcinogenic agents such as alcohol, tobacco, toxins, gamma rays and alpha particles. Besides the above-mentioned risk factors, conventional therapies such as radiotherapy, and chemotherapy have also been linked to the development of cancer. Over the past decade, tremendous efforts have been invested in the synthesis of eco-friendly green metallic nanoparticles (NPs), and their medical application. Comparatively, metallic NPs have greater advantages over conventional therapies. Additionally, metallic NPs can be functionalized with different targeting moieties e.g., liposomes, antibodies, folic acid, transferrin, and carbohydrates. Herein, we review and discuss the synthesis, and therapeutic potential of green synthesized metallic NPs for enhanced cancer photodynamic therapy (PDT). Finally, the advantages of green hybridized activatable NPs over conventional photosensitizers (PSs) and the future perspectives of nanotechnology in cancer research are discussed in the review. Furthermore, we anticipate that the insights offered in this review will inspire the design and development of green nano-formulations for enhanced image-guided PDT in cancer treatment.

Porphyrin Macrocycles: General Properties and Theranostic Potential

Despite specialists' efforts to find the best solutions for cancer diagnosis and therapy, this pathology remains the biggest health threat in the world. Global statistics concerning deaths associated with cancer are alarming; therefore, it is necessary to intensify interdisciplinary research in order to identify efficient strategies for cancer diagnosis and therapy, by using new molecules with optimal therapeutic potential and minimal adverse effects. This review focuses on studies of porphyrin macrocycles with regard to their structural and spectral profiles relevant to their applicability in efficient cancer diagnosis and therapy. Furthermore, we present a critical overview of the main commercial formulations, followed by short descriptions of some strategies approached in the development of third-generation photosensitizers.

The Combined Effect of Nanobubble-IR783-HPPH-Affibody Complex and Laser on HER2-Positive Breast Cancer

Introduction

Nanobubble is an innovative ultrasound contrast agent that triggers the development of targeted imaging of HER2-positive breast cancer by combining with HER2 affibody and IR783. HPPH is a second-generation photosensitiser that is effective in treating tumours. Hence, the nanobubble-IR783-HPPH-affibody (NIHA) complex demonstrates considerable potential in the treatment of HER2-positive breast cancer.

Methods

We fabricated the NIHA complex via an advanced thin-film hydration method and detected its characteristics such as particle size, morphology, stability, and cytotoxicity. Moreover, the effect of NIHA complex with laser on HER2-positive breast cancer was confirmed via in vitro and in vivo experiments.

Results

The NIHA complex was spheroid, stable and exhibited no cytotoxicity; moreover, its particle size was 524.8 ± 53.3 nm (n = 5). In combination with laser treatment, NIHA complex reduced the cell viability and tumour volume, induced apoptosis of HER2-positive breast cancer cells, and prolonged survival of nude mice.

Conclusion

The newly prepared NIHA complex with laser treatment has the potential on treating HER2-positive breast cancer.

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.

Biomimetic Photo-Switches Softening Model Lipid Membranes

We report the synthesis and characterization of a novel photo-switch based on biomimetic cyclocurcumin analogous and interacting with the lipid bilayer, which can be used in the framework of oxygen-independent light-induced therapy. More specifically, by using molecular dynamics simulations and free energy techniques, we show that the inclusion of hydrophobic substituents is needed to allow insertion in the lipid membrane. After having confirmed experimentally that the substituents do not preclude the efficient photoisomerization, we show through UV-vis and dynamic light scattering measurements together with compression isotherms that the chromophore is internalized in both lipid vesicles and monomolecular film, respectively, inducing their fluidification. The irradiation of the chromophore-loaded lipid aggregates modifies their properties due to the different organization of the two diastereoisomers, E and Z. In particular, a competition between a fast structural reorganization and a slower expulsion of the chromophore after isomerization can be observed in the kinetic profiles recorded during E to Z photoisomerization. This report paves the way for future investigations in the optimization of biomimetic photoswitches potentially useful in modern light-induced therapeutic strategies.

Enhanced Photodynamic Therapy: A Review of Combined Energy Sources

Photodynamic therapy (PDT) has been used in recent years as a non-invasive treatment for cancer, due to the side effects of traditional treatments such as surgery, radiotherapy, and chemotherapy. This therapeutic technique requires a photosensitizer, light energy, and oxygen to produce reactive oxygen species (ROS) which mediate cellular toxicity. PDT is a useful non-invasive therapy for cancer treatment, but it has some limitations that need to be overcome, such as low-light-penetration depths, non-targeting photosensitizers, and tumor hypoxia. This review focuses on the latest innovative strategies based on the synergistic use of other energy sources, such as non-visible radiation of the electromagnetic spectrum (microwaves, infrared, and X-rays), ultrasound, and electric/magnetic fields, to overcome PDT limitations and enhance the therapeutic effect of PDT. The main principles, mechanisms, and crucial elements of PDT are also addressed.

A novel 450-nm laser-mediated sinoporphyrin sodium-based photodynamic therapy induces autophagic cell death in gastric cancer through regulation of the ROS/PI3K/Akt/mTOR signaling pathway

BACKGROUND

Photodynamic therapy (PDT) has become an ideal and promising therapeutic method for fighting cancer, but its common application in clinical practice is prevented by the limitations of expensive devices in light sources and phototoxicity in photosensitizers. The aim of this study was to explore the antitumor efficiency of the novel 450-nm blue laser (BL) combined with sinoporphyrin sodium (DVDMS)-mediated PDT against human gastric cancer (GC) in vitro and in vivo, focusing on autophagy pathway.

METHODS

Cell viability was detected by Cell Counting Kit-8 and colony formation assays in HGC27, MGC803, AGS, and GES-1 cells. Cell apoptosis was measured by flow cytometry and western blotting. The production of reactive oxygen species (ROS) was measured by fluorescence microscopy and flow cytometry. Autophagy was determined by transmission electron microscopy and western blotting. The antitumor effect of BL-PDT in vivo was detected by a subcutaneous tumor model in nude mice.

RESULTS

The novel 450-nm laser-mediated DVDMS-based PDT caused remarkable growth inhibition and apoptosis induction in GC cells in vitro by the production of excessive ROS. Autophagy flux was induced by BL-PDT in GC cells, as determined by LC3 conversion assay, LC3 turnover assay, and mRFP-GFP-LC3 puncta assay. Furthermore, autophagy induction was demonstrated to positively contribute to BL-PDT-induced apoptotic effects on GC cells. Mechanically, ROS/PI3K/Akt/mTOR pathway was identified to involve in the regulation of BL-PDT-induced autophagy as determined by transcriptomic analysis and functional studies. Consistently, xenograft studies confirmed the significant antitumor effect of BL-PDT and its favorable safety in vivo.

CONCLUSIONS

The novel 450-nm laser-mediated DVDMS-based PDT may be a safe and effective approach against GC. Our results thus provide compelling evidence for the therapeutic application of BL-PDT in human GC.