Self-assembled Porphyrin Research Articles

The interaction of a self-assembled nanoparticle and a lipid membrane: Binding, disassembly and re-distribution

Here we report a detailed study of the interactions of nanoparticles, formed by the self-assembly of cholesterol-containing porphyrins, with lipid membranes. We show that the interaction is a two-step process: first, the docking and fusion, then, the redistribution of the building blocks of the self-assembled nanoparticles (SANs henceforth). Analysis of the binding and structural data is consistent with the docking step being driven by a multivalence cooperative effect and with the formation of SAN aggregates on the membrane, whilst the solubility of the cholesterol anchor in the membrane is key to both the fusion and redistribution of the SANs building blocks. The tendency of the SAN to aggregate in the membrane helps explain the photosensitizer properties of the SANs, essential to their anti-microbial activity. The solubility of the cholesteryl anchors drives fusion to the membrane and de-assembly of the SAN, explaining the capability of the SANs to deliver therapeutic cargos at the lipid interface. The subsequent redistribution of the SANs building blocks offer a plausible pathway to body clearance that is not immediately available to hard nanoparticles. These properties, and the modularity of the synthesis, point to the SANs being an excellent platform for the development of nanomedicines. An unexpected consequence of unraveling the mechanism of membrane interaction of these SANs is that it allows us to derive a value of the free energy of binding of cholesterol (the membrane anchor of the SAN building blocks) to a lipid membrane, that is consistent with the literature values. This is an additional property that can be exploited to determine the affinity of a variety of membrane anchors to membranes of various compositions.

Precise tuning of porphyrin self-assembly and photo-activated antimicrobial activity via metal ion coordination

Bacterial drug resistance has emerged as a significant threat to global human health, prompting the need for alternative antimicrobial strategies. Photodynamic therapy (PDT) has garnered widespread attention as a promising antimicrobial approach that circumvents the issue of bacterial resistance. Porphyrin is a class of photosensitizers with promising potential. In this study, we utilized the strategy of precise tuning of self-assembly of porphyrin through the coordination of metal ions to achieve the efficient and selective photo-activated antimicrobial. Typically, the selected porphyrin (TPPS4) serves as the foundation for an investigation into the role of metal ions (Mn+) as regulatory agents. The coordination of various metal ions (Bi3+, Ca2+, Zn2+, and Mn2+), with TPPS4 results in differentiated molecular stacking, which in turn affects the morphology of the self-assembled structures and their capacity to generate reactive oxygen species (ROS), ultimately leading to varied antimicrobial activities. The study found that the antibacterial capability of the system is positively correlated with its ability to generate reactive oxygen species (TPPS4-Bi ≈ TPPS4-Ca > TPPS4 >TPPS4-Zn >TPPS4-Mn). This work paves the way for the development of novel photodynamic antimicrobial agents that are both highly potent and minimally toxic, offering a significant advancement in the field of antimicrobial therapy.

Designing sandwich-structured IBP nanosheets with superior antioxidant property to enhance corrosion resistance, flame retardancy, and wear resistance for polymeric coatings

The rapid development of industrialization requires the advancement of multifunctional coatings. In this study, successful self-assembly of iron porphyrin on BP nanosheets resulted in the synthesis of IBP nanosheets with a sandwich structure. Characterization tests including SEM, XPS, SPM, and XRD confirmed the successful preparation of IBP nanosheets with robust structural stability and antioxidation. Subsequently, a water-based epoxy resin (WEP) coating containing IBP nanosheets was prepared. Test results revealed that the composite coating containing 0.4 wt.% IBP nanosheets exhibited outstanding anti-corrosion, wear-resistant, and flame-retardant properties. After 42 days of immersion in a 3.5 wt.% NaCl solution, the Rct value of the 4-IBP/WEP coating was 1.79 × 109 Ω cm2, surpassing the Pure WEP coating by more than 3 orders of magnitude. Additionally, the peak heat release rate (PHRR) and wear rate of the 4-IBP/WEP coating decreased by 19.29 % and 90.97 % compared to the Pure WEP coating. This research presents a novel idea for the utilization of BP nanosheets in multifunctional coatings.

Facile synthesis of g-C3N4@porphyrin nanofiber composite via self-assembly as photoelectrode for efficient photoelectrochemical water splitting

The creation of self-assembled porphyrin nanostructures and their organised arrays has garnered significant attention, with the objective of mimicking natural light-harvesting mechanisms and energy storage, as well as pioneering novel nanostructured materials for use in photocatalytic processes. This study explored the formation of porphyrin nanofibers onto the surface of g-C3N4 via self-assembly, creating a photoelectrode with remarkable potential for efficient photoelectrochemical (PEC) water splitting. By integrating these two distinct materials, the resultant hybrid structure leverages the unique properties of both components, enhancing the overall performance of the photoelectrochemical system. The fabrication process involves acid-base neutralization-induced self-assembly, leading to the formation of a well-distributed composite. The resulting photoelectrode exhibits improved charge separation and enhanced light absorption properties. Experimental analyses, encompassing techniques such as scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), and photocurrent measurements, validate the successful integration of the hybrid material and its notable photocatalytic efficiency. The porphyrin nanofiber was evenly distributed over the surface of the generated g-C3N4@porphyrin hybrid material. The photoelectrochemical measurements showed a remarkable enhancement in the photocurrent when using g-C3N4@porphyrin photoelectrode in the light-irradiating condition compared to the dark condition. The possible PEC water-splitting mechanism by g-C3N4@porphyrin photoelectrode was also proposed and discussed. This work showcases a promising avenue for advancing the field of photoelectrochemical water splitting through innovative material design and assembly strategies.

Complementary metalloporphyrin-based nanostructure decorated with silver nanoparticles for photocatalytic degradation of organic dyes

A hybrid composite photocatalyst, SA-T@Ag, was fabricated by the photoreduction of silver salts in the presence of nanomaterials composed of self-assembled complementary porphyrin triad SA-T. We confirmed the formation of SA-T@Ag from SA-T using various spectroscopic techniques, including X-ray diffraction (XRD), infrared (IR) spectroscopy, UV–visible spectroscopy, and fluorescence spectroscopy. Field emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM) investigations revealed that a substantial amount of silver nanoparticles (AgNPs) were deposited on the surface of SA-T and that the microstructure of SA-T was intact during photoreduction. The formation of AgNPs on the surface of SA-T reduced the band gap energy (Eg) of SA-T@Ag compared to that of SA-T. This not only improves its light-harvesting properties but also delays the recombination of photogenerated electron-hole pairs, which promotes more reactivity under visible light irradiation and improves the efficiency of polluted dye degradation. These photophysical properties are reflected in the degradation of methylene blue (MB) dye under visible light irradiation. The first-order degradation rate constant of MB dye within 45 min of visible light irradiation is much higher for SA-T@Ag (0.081 min−1) than SA-T (0.028 min−1). This report is of great importance in the field of environmental remediation and provides new opportunities for designing porphyrin-based photocatalytic systems as alternatives to conventional photocatalysts.

Enhancement of the Rates for Insertion of Zinc(II) Ions into a Cationic Porphyrin Catalyzed by Poly(glutamate).

The self-assembly of porphyrins onto polyelectrolytes could lead to interesting changes in their reactivity with respect to the bulk solution. Here, we investigated the kinetics of Zn2+ incorporation into tetra-cationic water-soluble 5,10,15,20-tetrakis-(N-methylpyridinium-4-yl)porphyrin (TMpyP(4)) in the presence of poly(L-glutamic acid) (PGA) in a pH range from 4 to 6.5. Under these conditions, the porphyrin electrostatically interacted with the polymer, which gradually switched from an α-helical to a random coil structure. The profile of the logarithm of the observed rate constant (kobs) versus the pH was sigmoidal with an inflection point close to the pH of the conformation transition for PGA. At a pH of 5.4, when PGA was in its highly charged random coil conformation, an almost 1000-fold increase in the reaction rates was observed. An increase in the ionic strength of the bulk solution led to a decrease in the metal insertion rates. The role of the charged matrix was explained in terms of its ability to assemble both reagents in proximity, in agreement with the theory of counter-ion condensation around polyelectrolytes in an aqueous solution.

Highly effective self-assembled porphyrin MOCs nanomaterials for enhanced photodynamic therapy in tumor

Porphyrins and their derivatives are excellent photosensitizers in photodynamic therapy (PDT). The modification of porphyrin molecules into metal-organic cages (MOCs) is a viable strategy to improve their bioavailability. In this work, MOC C66 based on porphyrin was synthesised by a one-pot self-assembly method. The three-dimensional structure of the metal-organic cage ameliorated the aggregation and self-quenching of porphyrins and increased the molar absorption coefficient in the visible light region, which enhanced the reactive oxygen species (ROS) yield of porphyrins and effectively improved the efficiency of photodynamic therapy. ROS generation ability tests in solution confirmed the improved reactive oxygen capacity of the cage, which showed greater phototoxicity to HeLa and MCF-7 cells in vitro, suggesting a new strategy for future modifications of the simple synthesis of porphyrins as photosensitizers.

Formation of Size-Controllable Tetragonal Nanoprisms by Crystallization-Directed Ionic Self-Assembly of Anionic Porphyrin and PEO-Containing Triblock Cationic Copolymer.

The creation of anisotropic nanostructures with precise size control is desirable for new properties and functions, but it is challenging for ionic self-assembly (ISA) because of the non-directional electrostatic interactions. Herein, the formation of size-controllable tetragonal nanoprisms is reported via crystallization-directed ionic self-assembly (CDISA) through evaporating a micellar solution on solid substrates. First, ISA is designed with a crystalline polyethylene oxide (PEO) containing cationic polymer poly(2-(2-guanidinoethoxy)ethyl methacrylate)-b-poly(ethyleneoxide)-b-poly(2-(2-guanidinoethoxy)-ethylmethacrylate) (PGn -PEO230 -PGn ) and an anionic 5,10,15,20-Tetrakis(4-sulfonatophenyl) porphyrin (TPPS) to form micelles in aqueous solution. The PG segments binds excessive TPPS with amplenet chargeto form hydrophilic corona, while the PEO segments are unprecedentedly dehydrated and tightly packed into cores. Upon naturally drying the micellar solution on a silicon wafer, PEO crystallizationdirects the micelles to aggregate into square nanoplates, which are further connected to nanoprisms. Length and width of the nanoprisms can be facilely tuned by varying the initial concentration. In this hierarchical process, the aqueous self-assembly is prerequisite and the water evaporation rate is crucial for the formation of nanostructures, which provides multiple factors for morphology regulating. Such precise size-control strategy is highly expected to provide a new vision for the design of advanced materials with size controllable anisotropic nanostructures.

Circularly polarized luminescence from porphyrin-containing (supra)molecular systems

Functional dyes showing circularly polarized luminescence (CPL) have attracted considerable attention. Porphyrins and porphyrinoids have characteristic properties useful for the development of CPL materials, although the examples of CPL-active porphyrins and porphyrinoids are still limited. Here we have summarized recent progress in CPL-active systems containing porphyrins or phthalocyanines, which are classified into the following four categories: (i) porphyrins with chiral sources; (ii) axially chiral porphyrin dimers; (iii) self-assembled porphyrins; (iv) porphyrin-sensitized CPL dyes.

Nanoarchitectonics of nitric oxide releasing supramolecular structures for enhanced antibacterial efficacy under visible light irradiation

Light‐controlled therapies offer a promising strategy to prevent and suppress infections caused by numerous bacterial pathogens. Excitation of exogenously supplied photosensitizers (PS) at specific wavelengths elicits levels of reactive oxygen intermediates toxic to bacteria. Porphyrin-based supramolecular nanostructure frameworks (SNF) are effective PS with unique physicochemical properties that have led to their widespread use in photomedicine. Herein, we developed a nitric oxide (NO) releasing, biocompatible, and stable porphyrin-based SNF (SNF-NO), which was achieved through a confined noncovalent self-assembly process based on π–π stacking. Characterization of the SNFs via scanning electron microscopy (SEM) and transmission electron microscopy (TEM) analysis showed the formation of three-dimensional, well-defined octahedral structures. These SNF-NO were shown to exhibit a red shift due to the noncovalent self-assembly of porphyrins, which also show extended light absorption to broadly cover the entire visible light spectrum to enhance photodynamic therapy (PDT). Under visible light irradiation (46 J cm−2), the SNF generates high yields of singlet oxygen (1O2) radicals, hydroxyl radicals (HO), superoxide radicals (O2), and peroxynitrite (ONOO−) radicals that have shown potential to enhance antimicrobial photodynamic therapy (APDT) against Gram-positive methicillin-resistant Staphylococcus aureus (MRSA) and Gram-negative Escherichia coli (E. coli). The resulting SNFs also exhibit significant biofilm dispersion and a decrease in biomass production. The combination of robust photosensitizer SNFs with nitric oxide-releasing capabilities is dynamic in its ability to target pathogenic infections while remaining nontoxic to mammalian cells. The engineered SNFs have enormous potential for treating and managing microbial infections.

Noble Metal Nanoparticle-Loaded Porphyrin Hexagonal Submicrowires Composites (M-HW): Photocatalytic Synthesis and Enhanced Photocatalytic Activity.

Surface plasmon resonance (SPR) photocatalysts have attracted considerable attention because of their strong absorption capacity of visible light and enhanced photogenic carrier separation efficiency. However, the separate production of metal nanoparticles (NPs) and semiconductors limits the photogenic charge transfer. As one of the most promising organic photocatalysts, porphyrin self-assemblies with a long-range ordered structure-enhance electron transfer. In this study, plasmonic noble metal-based porphyrin hexagonal submicrowires composites (M-HW) loaded with platinum (Pt), silver (Ag), gold (Au), and palladium (Pd) NPs were synthesized through a simple in situ photocatalytic method. Homogeneous and uniformly distributed metal particles on the M-HW composites enhanced the catalytic or chemical properties of the organic functional nanostructures. Under the same loading of metal NPs, the methyl orange photocatalytic degradation efficiency of Ag-HW [kAg-HW (0.043 min-1)] composite was three times higher than that of HW, followed by Pt-HW [kPt-HW (0.0417 min-1)], Au-HW [kAu-HW (0.0312 min-1)], and Pd-HW [kPd-HW (0.0198 min-1)]. However, the rhodamine B (RhB) and eosin B photocatalytic degradations of Pt-HW were 4 times and 2.6 times those of HW, respectively. Finally, the SPR-induced electron injection, trapping, and recombination processes of the M-HW system were investigated. These results showed that M-HW plasmonic photocatalysts exhibited excellent photocatalytic performances, making them promising materials for photodegrading organic pollutants.

Chiral template–induced porphyrin-based self-assembled materials for electrochemical chiral sensing

Chirality plays a key role in many fields of natural sciences as well as life sciences. Chiral materials are widely developed and used for electrochemical chiral recognition. In recent years, carbon quantum dots (CQDs) have been widely used as a novel carbon nanomaterial due to their excellent charge transfer properties, good biocompatibility, and low cost. The special structure of π-conjugated porphyrin attracts attention. Supramolecular self-assembly shows a way to construct chiral materials by self-assembling simple molecules into chiral composites. Herein, we demonstrate the self-assembly of achiral porphyrins induced by chiral carbon quantum dots assembled from L- and or D-tryptophan (L- and or D-Trp) with carbon quantum dots, resulting in 5,10,15,20-tetrakis (4-carboxyPheyl) (TCPP) self-assembled structure. The electrochemical chiral recognition of chiral self-assembled materials was studied using Phenylalanine (Phe) enantiomer as a chiral analyte. Electrochemical chiral recognition results showed that the chiral self-assembled materials induced by chiral templates have a good ability to discriminate Phe enantiomers. Therefore, this research provides a new idea for the synthesis of chiral composites and further expands applications to electrochemical chiral recognition.

Electrocatalytic Production of Hydrogen Peroxide Enabled by Post-Synthetic Modification of a Self-Assembled Porphyrin Cube.

Self-assembled metallacyles and cages formed via coordination chemistry have been used as catalysts to enforce 4H+/4e- reduction of oxygen to water with an emphasis on attenuating the formation of hydrogen peroxide. That said, the kinetically favored 2H+/2e- reduction to H2O2 is critically important to industry. In this work we report the synthesis, characterization, and electrochemical benchmarking of a hexa-porphyrin cube which catalyses the electrochemical reduction of molecular oxgyen to hydrogen peroxide. An established sub-component self-assembly approach was used to synthesize the cubic free-base porphryin topologies from 2-pyridinecarboxaldehyde, tetra-4-aminophenylporphryin (TAPP), and Fe(OTf)2 (OTf- = trifluoromethansulfonate). Then, a tandem metalation/transmetallation was used to introduce Co(II) into the porphyrin faces of the cube, and exchange with the Fe(II) cations at the vertices, furnishing a tetrakaideca cobalt cage. Electron paramagnetic resonance studies on a Cu(II)/Fe(II) analogue probed radical interactions which inform on electronic structure. The efficacy and selectivity of the CoCo-cube as a catalyst for hydrogen peroxide generation was investigated using hydrodynamic voltammetry, revealing a higher selectivity than that of a mononuclear Co(II) porphyrin (83% versus ~50%) with orders of magnitude enhancement in standard rate constant (ks = 2.2 × 102 M-1s-1 versus ks = 3 × 100 M-1s-1). This work expands the use of coordination-driven self-assembly beyond ORR to water by exploiting post-synthetic modification and structural control that is associated with this synthetic method.

Self-Assembly of Porphyrin to Realize the High Ionic Conductivity of Anion-Exchange Membranes

Self-Assembly of Porphyrin to Realize the High Ionic Conductivity of Anion-Exchange Membranes

Biomimetic Approach toward Visible Light-Driven Hydrogen Generation Based on a Porphyrin-Based Coordination Polymer Gel.

There has been a widespread interest in developing self-assembled porphyrin nanostructures to mimic nature's light-harvesting processes. Herein, porphyrin-based coordination polymer gel (CPG) has been developed as a "soft" photocatalyst material for hydrogen (H2) production from water under visible light. The CPG offers a hierarchical nanofibrous network structure obtained through self-assembly of a terpyridine alkyl-amide appended porphyrin (TPY-POR)-based low molecular weight gelator with ruthenium ions (RuII) and produces H2 with a rate of 5.7 mmol g-1 h-1 in the presence of triethylamine (TEA) as a sacrificial electron donor. Further, the [Fe2(bdt)(CO)6] (dbt = 1,2-benzenedithiol) cocatalyst, which can mimic the activity of iron hydrogenase, is coassembled in the CPG and shows remarkable improvement in H2 evolution (catalytic activity; rate ∼10.6 mmol g-1 h-1 and turnover number ∼1287). The significant enhancement in catalytic activity was supported by several controlled experiments, including femtosecond transient absorption (TA) spectroscopy and also DFT calculation. The TA study supported the cascade electron transfer process from porphyrin core to [Ru(TPY)2]2+ center, and subsequently, the electron transfers to the cocatalyst [Fe2(bdt)(CO)6] for H2 production.

Supramolecular nanoarchitectonics with TPPS porphyrin as a fluorescent probe for detection of aminoglycoside antibiotics and their photocatalytic applications for the degradation of rhodamine B dye

The meso-tetra(4-sulfonatophenyl)porphyrin (TPPS) porphyrin was successfully synthesized and applied as a selective turn-off sensor for detecting neomycin and gentamicin antibiotics in aqueous media. The sensing ability of TPPS porphyrin was studied by naked-eye detection as well as UV–vis absorption and fluorescence spectroscopy. The emission intensity of TPPS porphyrin was observed to be decreased dramatically upon addition of neomycin and gentamicin antibiotics. The quantum yield of TPPS porphyrin (56%) which decreases to 2% and 9% upon addition of neomycin and gentamycin, respectively. The quenching efficiency of neomycin and gentamicin towards the TPPS porphyrin was 99.13% and 96% respectively. The detection limit was calculated to be 7.5 × 108 M and 1.1 × 107 M for gentamicin and neomycin respectively, indicating both the antibiotics exhibited efficient quenching abilities. Moreover, the self-assembly of TPPS porphyrin with gentamicin antibiotic have been investigated using scanning electron microscopy (SEM), X-ray diffraction (XRD) and FTIR spectroscopy. Interestingly, TPPS porphyrin with 0–10 equiv. of gentamicin, produces nanorod-like structures. The key driving force for the formation of self-assembled nanostructure of TPPS porphyrin with gentamicin is H-bonding between sulfonate group of TPPS and –NH2 and –OH group of gentamicin. The-self-assembled nanostructure exhibited band gap energy in the range of 2.7 to 3 eV. Therefore, these nanostructures were used as a photocatalyst for degradation of RhB dye. Interestingly, nanostructure obtained from 1:2 equiv. of TPPS: gentamicin showed excellent photocatalytic performance, degraded almost 100% of RhB dye in aqueous media within 240 min. with simulated visible light irradiation with rate constant of 2 × 10−2 min−1. A possible mechanism for the photodegradation of RhB using nanorod like structure is also discussed.

Charge-dependent Self-assembly of a Water-soluble Porphyrin in a Variety of Dimensions

Porphyrins are basic compounds because of their central pyrrole units, potentially producing dications at their cores through protonation. When anionic and cationic groups are presented as peripheral groups, local charges can be introduced at the cores and peripheries of the porphyrins, providing derivatives with a variety of total charges. In this study we synthesized a new porphyrin derivative for which the total charge could be varied from −2, to 0, to +2. Charge neutralization–driven self-assembly of this porphyrin derivative controlled the pathways through which it formed various supramolecular structures at different values of pH.

Self-assembly of porphyrins on perovskite film for blade-coating stable large-area methylammonium-free solar cells

Phase transition and phase separation of formamidinium-cesium (FA-Cs) perovskite during the fabrication and operation processes reduce the efficiency and stability of perovskite solar cells (PSCs). Here, we develop an in situ molecular self-assembly approach on perovskite surface using an amine nickel porphyrin (NiP). The NiP doped perovskite precursor solution was deposited on substrate by blade-coating under ambient condition. NiP molecules self-assemble into supramolecule bound on perovskite surface during the vacuum-assisted process. Such a modification controls the perovskite grain growth to generate the uniform perovskite film. The supramolecule can release the residual lattice strain to inhibit the phase transition of perovskite film, and promote the charge extraction and transport to suppress the phase separation of FA-Cs perovskite during long-term illumination condition. Consequently, the best efficiency of large-area NiP-based FA-Cs-PSCs with the active area of 1.0 cm2 is up to 20.3% (certified as 19.2%), which is close to the record efficiency (20.37%) by blade-coating. Unencapsulated NiP-doped device reveals the remarkably improved overall stabilities. This work affords a novel way to address the phase transition and phase separation in FA-Cs perovskite.

Anion receptor-mediated multicomponent synergistic self-assembly of porphyrin for efficient phototherapy to elicit tumor immunotherapy

Immunogenic phototherapy has the potential to enhance tumor immunotherapy. Nevertheless, its efficacy is severely restricted by optimal photosensitizer deficiency and efficient delivery of the photosensitizers. We thus constructed TAPP-GCP@TCPP@BSA nanoparticles by self-assembling of a porphyrin derivative (TAPP-GCP), meso-tetra(4-carboxyphenyl) porphyrin (TCPP), and bovine serum albumin (BSA) to achieve effective phototherapy and further enhance tumor immunotherapy. Nanoparticles (NPs) subjected to laser irradiation can induce tumor cytotoxicity and immunogenic cell death (ICD). They can accumulate in tumors after intravenous injection and induce significant ICD after laser illumination, thereby promoting the maturation of antigen-presenting cells and activating the specific antitumor killing effect of cytotoxic T cells in a breast tumor model. NPs combined with anti-PD-L1 blockade significantly inhibited distant tumor growth by initiating an excellent antitumor immune response. The phototherapy of NPs through multicomponent synergistic self-assembly is a promising approach for boosting immune checkpoint blockade therapy.

Controllable self-assembly of porphyrins and their applications

<p indent="0mm">Porphyrins are cyclic molecules with large π-conjugated structure. They can form ordered nanostructures through controllable self-assembly <italic>via</italic> multiple non-covalent interactions, to regulate their photoelectric properties effectively. However, it is still a great challenge to accurately regulate the self-assembly process to obtain self-assembled nanostructures with controllable morphology, uniform size and ordered internal structure, and further to clarify the key factors controlling the performance. This paper reviews the development of solution phase self-assembly strategy of porphyrin self-assemblies in recent years and its applications in the fields of photocatalysis, chemical sensor and biological phototherapy, and preliminarily summarizes the structure-performance relationship between the morphology, size and internal structure of porphyrin self-assembled nanostructures and related applications.