Newly Synthesized Lipid-Porphyrin Conjugates: Evaluation of Their Self-Assembling Properties, Their Miscibility with Phospholipids and Their Photodynamic Activity In Vitro

Porphysome Engineered With Specific Protein Binding Sites as a Multimodal Theranostic Nanocarrier for Targeted Protein Delivery

The immobilization of proteins on the surface of carriers is challenging due to the loss of protein structure and function in this process. Here, we report the development of the protein immobilization on the surface of the metallated-porphyrin complex in the porphysome nanocarrier. The conjugated Ni-porphyrin to fatty acid (as a tail) has been synthesized and independently placed at the depth of the bilayer center of Dipalmitoylphosphatidylcholine (DPPC) in which the Ni-porphyrin was at the polar region of the membrane and is thus superficial. This porphysome (DPPC: Ni-porphyrin, 4 : 1 mole ratio) was formed by supramolecular self-assembly with a diameter of 173±7 nm and zeta potential -8.5±3.4 mv, which exhibited no significant toxicity at the experimental concentrations and acceptable cellular uptake on MCF-7 cells. The physicochemical properties and specific protein binding sites of the firefly luciferase as a model protein into the porphysome (1 : 2 mole ratio) show the conjugation efficiency about 80 % and the conformation of protein was completely maintained. Furthermore, bioluminescence assay and SDS-PAGE confirmed the preservation of protein function. The stabilized platform of porphyrin-lipid structure can potentially improve the efficacy of protein functionality for a particular display, shifting porphysomes from a simple carrier to a therapeutic agent.

Thermodynamic and structural properties of lipid-photosensitizer conjugates mixed with phospholipids: Impact on the formation and stability of nano-assemblies

The photosensitizer Phenalenone (PN) was grafted with one or two lipid (C18) chains to form pure nano-assemblies or mixed lipid vesicles suitable for photodynamic therapy. Mixtures of PN-C18 conjugates with stearoyl-oleoyl phosphatidylcholine (SOPC) form vesicles that disintegrate into bilayer sheets as the concentration of PN-C18 conjugates increases. We hypothesized that PN-C18 conjugates control the thermodynamic and structural properties of the mixtures and induce the disintegration of vesicles due to PN π-π-interactions. Monolayers were analyzed by surface pressure and grazing incidence X-ray diffraction (GIXD) measurements, and vesicles by differential scanning calorimetry and cryo-TEM. The results showed that PN-triazole-C18 (1A) and PN-NH-C18 (1B) segregate from the phospholipid domains. PN-(C18)2 (conjugate 2) develops favorable interactions with SOPC and distearoyl-phosphatidylcholine (DSPC). GIXD demonstrates the contribution of SOPC to the structuring of conjugate 2 and the role of the major component in controlling the structural properties of DSPC-conjugate 2 mixtures. Above 10 mol% conjugate 2 in SOPC vesicles, the coexistence of domains with different molecule packing leads to conjugate segregation, vesicle deformation, and the formation of small bilayer discs stabilized by the inter-bilayer π-π stacking of PN molecules.

RNA Nanomedicine: Delivery Strategies and Applications

Delivery of RNA using nanomaterials has emerged as a new modality to expand therapeutic applications in biomedical research. However, the delivery of RNA presents unique challenges due to its susceptibility to degradation and the requirement for efficient intracellular delivery. The integration of nanotechnologies with RNA delivery has addressed many of these challenges. In this review, we discuss different strategies employed in the design and development of nanomaterials for RNA delivery. We also highlight recent advances in the pharmaceutical applications of RNA delivered via nanomaterials. Various nanomaterials, such as lipids, polymers, peptides, nucleic acids, and inorganic nanomaterials, have been utilized for delivering functional RNAs, including messenger RNA (mRNA), small interfering RNA, single guide RNA, and microRNA. Furthermore, the utilization of nanomaterials has expanded the applications of functional RNA as active pharmaceutical ingredients. For instance, the delivery of antigen-encoding mRNA using nanomaterials enables the transient expression of vaccine antigens, leading to immunogenicity and prevention against infectious diseases. Additionally, nanomaterial-mediated RNA delivery has been investigated for engineering cells to express exogenous functional proteins. Nanomaterials have also been employed for co-delivering single guide RNA and mRNA to facilitate gene editing of genetic diseases. Apart from the progress made in RNA medicine, we discuss the current challenges and future directions in this field.

Luminescent iridium(III) porphyrin complexes as near-infrared-emissive biological probes

We report herein the design, synthesis and characterisation of a series of luminescent iridium(III) porphyrin complexes [Ir(ttp)(CH2CH2OH)] (H2ttp = 5,10,15,20-tetra-4-tolylporphyrin) (1), [Ir(tpp-Ph-NO2)(CO)Cl] (H2tpp-Ph-NO2 = 5-(4-((4-nitrophenoxy)carbonyloxymethyl)phenyl)-10,15,20-triphenylporphyrin) (2), [Ir(tpp-COOMe)(Py)2](Cl) (H2tpp-COOMe = 5-(4-methoxycarbonylphenyl)-10,15,20-triphenylporphyrin; Py = pyridine) (3) and [Ir(tpp-COOH)(Py)2](Cl) (H2tpp-COOH = 5-(4-carboxylphenyl)-10,15,20-triphenylporphyrin) (4). All the complexes displayed long-lived near-infrared (NIR) emission attributed to an excited state of mixed triplet intraligand (3IL) (π → π*) (porphyrin) and triplet metal-to-ligand charge transfer (3MLCT) (dπ(Ir) → π*(porphyrin)) character. The cytotoxicity of the complexes toward HeLa cells was examined by the 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyltetrazolium bromide (MTT) assay. The cationic complexes 3 and 4 exhibited higher cytotoxic activity toward HeLa cells than their neutral counterparts 1 and 2. Cellular uptake studies by inductively coupled plasma-mass spectrometry (ICP-MS) and laser-scanning confocal microscopy (LSCM) indicated that complexes 3 and 4 showed higher cellular uptake efficiencies than complexes 1 and 2 due to their cationic charge, and they were enriched in the perinuclear region of the cells with negligible nuclear uptake. Additionally, the carboxyl complex 4 was used to label a model protein bovine serum albumin (BSA) via an amidation reaction. The resultant luminescent protein conjugate 4-BSA displayed similar photophysical properties and intracellular localisation behaviour to its parent complex. The results of this work will contribute to the development of luminescent iridium(III) porphyrin complexes and related bioconjugates as NIR-emissive probes for bioimaging applications.

Engineered Lipidic Nanomaterials Inspired by Sphingomyelin Metabolism for Cancer Therapy

Sphingomyelin (SM) and its metabolites are crucial regulators of tumor cell growth, differentiation, senescence, and programmed cell death. With the rise in lipid-based nanomaterials, engineered lipidic nanomaterials inspired by SM metabolism, corresponding lipid targeting, and signaling activation have made fascinating advances in cancer therapeutic processes. In this review, we first described the specific pathways of SM metabolism and the roles of their associated bioactive molecules in mediating cell survival or death. We next summarized the advantages and specific applications of SM metabolism-based lipidic nanomaterials in specific cancer therapies. Finally, we discussed the challenges and perspectives of this emerging and promising SM metabolism-based nanomaterials research area.

Self-Organization of Lipid-Porphyrin Conjugates at the Air/Water Interface

Lipid-porphyrin conjugates are versatile compounds which can self-assemble into liposome-like structures with multifunctional properties. Most of the conjugates that have been described so far, consisted in grafting pyropheophorbide-a (Pyro-a) or other porphyrin derivatives through the esterification of the hydroxyl group in the sn-2 position of a lysophosphatidylcholine. However, despite the versatility of these conjugates, less is known about the impact of the lipid backbone structure on their 2D phase behavior at the air/water interface and more precisely on their fine structures normal to the interface as well as on their in-plane organization. Herein, we synthesized a new lipid-porphyrin conjugate (PyroLSM) based on the amide coupling of Pyro-a to a lysosphingomyelin backbone (LSM) and we compared its interfacial behavior to that of Pyro-a and Pyro-a conjugated lysophosphatidylcholine (PyroLPC) using Langmuir balance combined to a variety of other physical techniques. Our results provided evidence on the significant impact of the lipid backbone on the lateral packing of the conjugates as well as on the shape and size of the formed domains. Compared to Pyro-a and PyroLPC monolayers, PyroLSM exhibited the highest lateral packing which highlights the role of the lipid backbone in controlling their 2D organization which in turn may impact the photophysical properties of their assemblies.

Conjugates of Tetrapyrrolic Macrocycles as Potential Anticancer Target-Oriented Photosensitizers

Photodynamic therapy is a minimally invasive treatment of tumors using photosensitizers, light, and reactive oxygen species, which can destroy cellular structures. With the development of photodynamic therapy, significant efforts have been made to create new efficient photosensitizers with improved delivery to cells, stability, and selectivity against cancer tissues. Naturally occurring tetrapyrrolic macrocycles, such as porphyrins and chlorins, are very attractive as photosensitizers, and their structural modification and conjugation with other biologically active molecules are promising approaches for creating new photosensitizers specifically targeting cancer cells. The present review aims to highlight recent developments in the design, preparation, and investigation of complex conjugates of tetrapyrrolic macrocycles, which can potentially be used as sensitizers for target-oriented photodynamic therapy of cancer. In this review, we discuss the structure, photodynamic effect, and anticancer activity of the following conjugates of tetrapyrrolic macrocycles: (1) conjugates obtained by modifying peripheral substituents in porphyrins and chlorins; (2) conjugates of porphyrins and chlorins with lipids, carbohydrates, steroids, and peptides; (3) conjugates of porphyrins and chlorins with anticancer drugs and some other biologically active molecules; (4) metal-containing conjugates. The question of how the conjugate structure affects its specificity, internalization, localization, and photoinduced toxicity within cancer cells is the focus of this review.

Organization of the Interfacial Film of Nanoemulsions Stabilized by Porphyrin Derivatives

Photodynamic therapies combining the action of a photosensitizer (PS), molecular oxygen, and light make it possible to destroy certain infectious sites and tumors. The incorporation of photosensitizers in nanocarriers allows for better control of their distribution in tissues and increases their concentration in the area that will be then illuminated. Nanoemulsions of glyceryl trioctanoate (GTO) have been designed in which pyropheophobide a (Pyro-A) or its lipid conjugate (Pyro-Lipid) are both stabilizing and photostimulable agents. In this work, we studied by surface pressure measurements and Brewster angle microscopy (BAM) analysis the organization of the interfacial films of nanodroplets. Comparison of preformed porphyrin nanoemulsions and two porphyrin-GTO mixtures, one mimicking the composition of the nanoemulsions and the other that of a porphyrin-rich interfacial film, highlighted the role of GTO and porphyrin derivatives in the formation, organization, and elasticity of the interfacial films in nanoemulsions. Pyro-Lipid and GTO can mix, and some of the GTO molecules remain inserted in the interfacial film at high surface pressures. In contrast, Pyro-A and GTO do not mix well and tend to segregate, leaving Pyro-A alone in the condensed interfacial film. The results of this study demonstrate the importance of characterizing the interfacial properties of porphyrin derivatives and their interaction with the oil to design stable nanoemulsions with well-controlled optical properties.

Novel liposome-like assemblies composed of phospholipid-porphyrin conjugates with photothermal and photodynamic activities against bacterial biofilms

Phospholipid-Porphyrin (PL-Por) conjugates are unique building blocks that can self assemble into liposome-like structures with improved photophysical properties compared to their monomeric counterparts. The high packing density of porphyrin moieties enables these assemblies to exhibit high photothermal conversion efficiency as well as photodynamic activity. Thus, PL-Por conjugates assemblies can be used for photodynamic therapy (PDT) and photothermal therapy (PTT) applications against resistant bacteria and biofilms. In order to tune the PD/PT properties of such nanosystems, we developed six different supramolecular assemblies composed of newly synthesized PL-Por conjugates bearing either pheophorbide-a (Ph_xLPC) or pyropheophorbide-a (Pyr_xLPC) photosensitizers (PSs) for combined PDT/PTT against planktonic bacteria and their biofilms. In this study, the influence of the chemical structure of the phospholipid backbone as well as that of the PS on the photothermal conversion efficiency, the photodynamic activity and the stability of these assemblies in biological medium were determined. Then their antimicrobial efficiency was assessed on S. aureus and P. aeruginosa planktonic cultures and biofilms. The two studied systems show almost the same photothermal effect against planktonic cultures and biofilms of S. aureus and P. aeruginosa. However, Ph_xLPC vesicles exhibit superior photodynamic activity, making them the best combination for PTT/PDT. Such results highlight the higher potential of the photodynamic activity of PL-Por nanoassemblies compared to their photothermal conversion in combating bacterial infections.

Phospholipid-porphyrin conjugates: deciphering the driving forces behind their supramolecular assemblies

Phospholipid-porphyrin conjugates (PL-Por) are nowadays considered as a unique class of building blocks that can self-assemble into supramolecular structures that possess multifunctional properties and enhanced optoelectronics characteristics compared to their disassembled counterparts. However, despite their versatile properties, little is known about the impact of the packing parameter of PL-Por conjugates on their assembling mechanism and their molecular organization inside these assemblies. To gain a better understanding on their assembling properties, we synthesized two new series of PL-Por conjugates with different alkyl sn2-chain lengths linked via an amide bond to either pheophorbide-a (Ph_xLPC) or pyropheophorbide-a (Pyr_xLPC). By combining a variety of experimental techniques with molecular dynamics (MD) simulations, we investigated both the assembling and optical properties of the PL-Por either self-assembled or when incorporated into lipid bilayers. We demonstrated that independently of the linker length, Ph_xLPC assembled into closed ovoid structures, whereas Pyr_xLPC formed rigid open sheets. Interestingly, Pyr_xLPC assemblies displayed a significant red shift and narrowing of the Q-band indicating the formation of ordered J-aggregates. The MD simulations highlighted the central role of the interaction between porphyrin cores rather than the length difference between the two phospholipid chains in controlling the structure of the lipid bilayer membranes and thus their optical properties. Indeed, while Ph_xLPC have the tendency to form inter-leaflet π-stacked dimers, Pyr_xLPC conjugates formed dimers within the same leaflet. Altogether, this work could be used as guidelines for the design of new PL-Por conjugates that self-assemble into bilayer-like supramolecular structures with tunable morphology and optical properties.

The biological activities of 5,15-diaryl-10,20-dihalogeno porphyrins for photodynamic therapy

PURPOSE

Esophageal cancer is the most common gastrointestinal tumor and is difficult to be eradicated with conventional treatment. Porphyrin-based photosensitizers (PSs) mediated photodynamic therapy (PDT) could kill tumor cells with less damage to normal cells. As the most widely used porphyrin-based photosensitizer in clinics, Photofrin II has excellent anti-tumor effect. However, it has some disadvantages such as weak absorption at near infrared region, the complexity of components and prolonged skin photosensitivity. Here series novel 5,15-diaryl-10,20-dihalogeno porphyrin derivatives were afforded and evaluated to develop more effective and safer photosensitizers for tumor therapy.

METHODS

The photophysical properties and singlet oxygen generation rates of 5,15-diaryl-10,20-dihalogeno porphyrins (I_1-6, II_1-4) were tested. The cytotoxicity of I_1-6 and II_1-4 were measured by MTT assay. The pathway of cell death was studied by flow cytometry. In vivo photodynamic efficacy of I₃ and II_2-4 in Eca-109 tumor-bearing BABL/c nude mice were measured and histopathological analysis were examined.

RESULTS

5,15-Diaryl-10,20-dihalogeno porphyrins I_1-6 and II_1-4 were synthesized. The longest absorption wavelength of these halogenated porphyrins (λ_max = 660 nm) displayed a red shift around 30 nm compared to the unhalogenated porphyrins PS₁ (λ_max = 630 nm). The singlet oxygen generation rates of I_1-6 and II_1-4 were significantly higher than PS₁ and HMME. All PSs mediated PDT showed obvious cytotoxic effect against Eca-109 cells compared to HMME in vitro and in vivo. Among these PSs, II₄ exhibited appropriate absorption in the phototherapeutic window, higher ¹O₂ generation rate (k = 0.0061 s^-1), the strongest phototoxicity (IC₅₀ = 0.4 μM), lower dark toxicity, high generation of intracellular ROS in Eca-109 cells and excellent photodynamic anti-tumor efficacy in vivo. Besides, cell necrosis was induced by compound II₄ mediated PDT.

CONCLUSION

All new compounds have obvious photodynamic anti-esophageal cancer effects. Among them, the photosensitizer II₄ showed excellent efficacy in vitro and in vivo, which has the potential to become a photodynamic anti-tumor drug.

Influence of the porphyrin structure and linker length on the interfacial behavior of phospholipid-porphyrin conjugates

HYPOTHESIS

Phospholipid-porphyrin (Pl-Por) conjugates consist of porphyrin derivatives grafted to a lysophosphatidylcholine backbone. Owing to their structural similarities with phospholipids, Pl-Por conjugates can self-assemble into liposome-like assemblies. However, there is a significant lack of information concerning the impact of the porphyrin type and the length of the alkyl chain bearing the porphyrin on the interfacial behavior of the Pl-Por conjugates. We hypothesized that changing the chain length and the porphyrin type could impact their two-dimensional phase behavior and modulate the alignment between the two chains.

EXPERIMENTS

6 Pl-Por conjugates with different alkyl chain lengths in the sn2 position of C16 lysophosphatidylcholine and coupled to either pheophorbide-a or pyropheophorbide-a were synthesized. Their interfacial behavior at the air/water interface was assessed using Langmuir balance combined to a variety of other physical techniques including Brewster angle microscopy, atomic force microscopy and X-ray reflectometry.

FINDINGS

Our results showed that all 6 Pl-Por form stable monolayers with the porphyrin moiety at the air/water interface. We also showed that changing the porphyrin moiety controlled the packing of the monolayer and thus the formation of organized domains. The chain length dictated the structure of the formed domains with no evidence of the alignment between the two chains.

Photo-triggerable liposomes based on lipid-porphyrin conjugate and cholesterol combination: Formulation and mechanistic study on monolayers and bilayers

Lipid-porphyrin conjugates are considered nowadays as promising building blocks for the conception of drug delivery systems with multifunctional properties such as photothermal therapy (PTT), photodynamic therapy (PDT), phototriggerable release, photoacoustic and fluorescence imaging. For this aim, we have recently synthesized a new lipid-porphyrin conjugate named PhLSM. This was obtained by coupling pheophorbide-a (Pheo-a), a photosensitizer derived from chlorophyll-a, to egg lyso-sphingomyelin. The pure PhLSMs were able to self-assemble into vesicle-like structures that were however not stable and formed aggregates with undefined structures due to the mismatch between the length of the alkyl chain in sn-1 position and the adjacent porphyrin. Herein, stable PhLSMs lipid bilayers were achieved by mixing PhLSMs with cholesterol which exhibits a complementary packing parameter. The interfacial behavior as well as the fine structures of their equimolar mixture was studied at the air/buffer interface by the mean of Langmuir balance and x-ray reflectomerty (XRR) respectively. Our XRR analysis unraveled the monolayer thickening and the increase in the lateral ordering of PhLSM molecules. Interestingly, we could prepare stable vesicles with this mixture that encapsulate hydrophilic fluorescent probe. The light-triggered release kinetics and the photothermal conversion were studied. Moreover, the obtained vesicles were photo-triggerable and allowed the release of an encapsulated cargo in an ON-OFF fashion.

Membrane composition is a functional determinant of NIR-activable liposomes in orthotopic head and neck cancer

Near-infrared (NIR)-activable liposomes containing photosensitizer (PS)-lipid conjugates are emerging as tunable, high-payload, and tumor-selective platforms for photodynamic therapy (PDT)-based theranostics. To date, the impact that the membrane composition of a NIR-activable liposome (the chemical nature and subsequent conformation of PS-lipid conjugates) has on their in vitro and in vivo functionality has not been fully investigated. While their chemical nature is critical, the resultant physical conformation dictates their interactions with the immediate biological environments. Here, we evaluate NIR-activable liposomes containing lipid conjugates of the clinically-used PSs benzoporphyrin derivative (BPD; hydrophobic, membrane-inserting conformation) or IRDye 700DX (hydrophilic, membrane-protruding conformation) and demonstrate that membrane composition is critical for their function as tumor-selective PDT-based platforms. The PS-lipid conformations were primarily dictated by the varying solubilities of the two PSs and assisted by their lipid conjugation sites. Conformation was further validated by photophysical analysis and computational predictions of PS membrane partitioning (topological polar surface area [tPSA], calculated octanol/water partition [cLogP], and apparent biomembrane permeability coefficient [P_app]). Results show that the membrane-protruding lipo-IRDye700DX exhibits 5-fold more efficient photodynamic generation of reactive molecular species (RMS), 12-fold expedited phototriggered burst release of entrap-ped agents, and 15-fold brighter fluorescence intensity as compared to the membrane-inserting lipo-BPD-PC (phosphatidylcholine conjugate). Although the membrane-inserting lipo-BPD-PC exhibits less efficient photo-dynamic generation of RMS, it allows for more sustained phototriggered release, 10-fold greater FaDu cancer cell phototoxicity, and 7.16-fold higher tumor-selective delivery in orthotopic mouse FaDu head and neck tumors. These critical insights pave the path for the rational design of emerging NIR-activable liposomes, whereby functional consequences of membrane composition can be tailored toward a specific therapeutic purpose.

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

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

Flavin-Conjugated Nanobombs: Key Structural Requirements Governing Their Self-Assemblies' Morphologies

In contrast to artificial molecules, natural photosensitizers have the benefit of excellent toxicity profiles and of life-compatible activating energy ranges. Flavins are such photosensitizers that were selected by nature in a plethora of light-triggered biochemical reactions. Flavin-rich nanoparticles could thus emerge as promising tools in photodynamic therapies and in active-targeting drug delivery. Self-assembled flavin-conjugated phospholipids improve the pharmacokinetics of natural flavins and, in the case of controlled morphologies, reduce photobleaching phenomena. The current article presents a proof of concept for the design of riboflavin-rich nanoparticles of tunable morphology from multilamellar patches to vesicular self-assemblies. Coarse-grained simulations of the self-assembling process revealed the key interactions governing the obtained nanomaterials and successfully guided the synthesis of new flavin-conjugates of predictable self-assembly. The obtained flavin-based liposomes had a 65 nm hydrodynamic diameter, were stable, and showed potential photosensitizer activity.

Synthesis and evaluation of novel fluorinated hematoporphyrin ether derivatives for photodynamic therapy

A photosensitizer with high phototoxicity, suitable amphipathy and low dark toxicity could play a pivotal role in photodynamic therapy (PDT). In this study, a facile and versatile approach was adopted to synthesize a series of novel fluorinated hematoporphyrin ether derivatives (I1-I5 and II1-II4), and the photodynamic activities of these compounds were studied. Compared to hematoporphyrin monomethyl ether (HMME), all PSs showed preferable photodynamic activity against A549 lung tumor cells. The longest visible absorption wavelength of these compounds was approximately 622 nm. Among them, II3 revealed the highest singlet oxygen yield (0.0957 min-1), the strongest phototoxicity (IC50 = 1.24 μM), the lowest dark toxicity in vitro, and exhibited excellent anti-tumor effects in vivo. So compound II3 could act as new drug candidate for photodynamic therapy.

Growing tool-kit of photosensitizers for clinical and non-clinical applications

Photosensitizers are photosensitive molecules utilized in clinical and non-clinical applications by taking advantage of light-mediated reactive oxygen generation, which triggers local and systemic cellular toxicity. Photosensitizers are used for diverse biological applications such as spatio-temporal inactivation of a protein in a living system by chromophore-assisted light inactivation, localized cell photoablation, photodynamic and immuno-photodynamic therapy, and correlative light-electron microscopy imaging. Substantial efforts have been made to develop several genetically encoded, chemically synthesized, and nanotechnologically driven photosensitizers for successful implementation in redox biology applications. Genetically encoded photosensitizers (GEPS) or reactive oxygen species (ROS) generating proteins have the advantage of using them in the living system since they can be manipulated by genetic engineering with a variety of target-specific genes for the precise spatio-temporal control of ROS generation. The GEPS variety is limited but is expanding with a variety of newly emerging GEPS proteins. Apart from GEPS, a large variety of chemically- and nanotechnologically-empowered photosensitizers have been developed with a major focus on photodynamic therapy-based cancer treatment alone or in combination with pre-existing treatment methods. Recently, immuno-photodynamic therapy has emerged as an effective cancer treatment method using smartly designed photosensitizers to initiate and engage the patient's immune system so as to empower the photosensitizing effect. In this review, we have discussed various types of photosensitizers, their clinical and non-clinical applications, and implementation toward intelligent efficacy, ROS efficiency, and target specificity in biological systems.

Synchrotron Scattering Methods for Nanomaterials and Soft Matter Research

This article aims to provide an overview of broad range of applications of synchrotron scattering methods in the investigation of nanoscale materials. These scattering techniques allow the elucidation of the structure and dynamics of nanomaterials from sub-nm to micron size scales and down to sub-millisecond time ranges both in bulk and at interfaces. A major advantage of scattering methods is that they provide the ensemble averaged information under in situ and operando conditions. As a result, they are complementary to various imaging techniques which reveal more local information. Scattering methods are particularly suitable for probing buried structures that are difficult to image. Although, many qualitative features can be directly extracted from scattering data, derivation of detailed structural and dynamical information requires quantitative modeling. The fourth-generation synchrotron sources open new possibilities for investigating these complex systems by exploiting the enhanced brightness and coherence properties of X-rays.

Nanoparticle-based drug delivery systems for controllable photodynamic cancer therapy

Compared with the traditional treatment, photodynamic therapy (PDT) in the treatment of malignant tumors has the advantages of less damage to normal tissues, quick therapeutic effect, and ability to repeat treatments to the same site. However, most of the traditional photosensitizers (PSs) have severe skin photosensitization, poor tumor targeting, and low therapeutic effect in hypoxic tumor environment, which limit the application of PDT. Nanoparticle-based drug delivery systems can improve the targeting of PSs and release drugs with controllable photoactivity at predetermined locations, so as to achieve desired therapeutic effects with minimal side-effects. The present review summarizes the current nanoparticle platforms for PDT, and offers the description of different strategies including tumor-targeted delivery, controlled-release of PSs and the triggered photoactivity to achieve controllable PDT by nanoparticle-based drug delivery systems. The challenges and prospects for further development of intelligent PSs for PDT are also discussed.

Reversible Aggregation of Chlorophyll Derivative Induced by Phase Transition of Lipid

Controlling the supramolecular organization of pigment molecules will provide innovative materials that exhibit variable optical properties. In nature, photosynthetic systems employ chlorophyllous supramolecules in which each pigment molecule is suitably organized in proteins, and their properties are adequately optimized by changing the structures of the surrounding amino acid residues. Here, we report a strategy for varying the aggregation behavior of a chlorophyll derivative by using a phase-transition phenomenon of lipid bilayers. Methyl pyropheophorbide a (MPP) was employed as a chlorophyllous pigment in our artificial system, and synthetic phosphatidylcholines with saturated acyl chain(s) were also used. The MPP molecules successfully accumulated within the lipid bilayer of liposomes without changing the vesicular structure. When the lipid bilayer was in a gel form (under the phase-transition temperature, T_m), the embedded MPP aggregated to yield a dimeric form showing red-shifted absorption bands and circular dichroism signals. When the solutions of MPP-containing liposomes were heated to higher temperatures than their T_m, MPP disaggregated to monomeric form as the absorption spectrum changed into its original fashion in dichloromethane. The reversible thermochromic (dis)aggregation of the MPP molecules had good cyclability. Additional careful examination of the phase transition in the MPP-lipid co-assemblies clarified that the critical temperatures of the MPP (dis)aggregation were in good agreement with the phase-transition temperatures of the pigment-containing bilayers. The reversible MPP aggregation in the lipid bilayers occurred in a wide range of temperatures (around 10-55 °C) by changing the length of the diacyl side chains of phospholipids. The reversible thermochromism of the chlorophyllous system was established by varying the nature of the surrounding lipid bilayer. This study can provide a useful strategy for making variable tetrapyrrolic aggregate systems induced by mild extrinsic stimuli.

Synthesis of a triphenylamine BODIPY photosensitizer with D–A configuration and its application in intracellular simulated photodynamic therapy

A D–A type triphenylamine BODIPY fluorescent dye with AIE characteristics makes progress in photodynamic therapy.