Synthesis of Self-Assembled Porphyrin Nanoparticle Photosensitizers

Abstract

The use of nanoparticles as a potential building block for photosensitizers has recently become a focus of interest in the field of photocatalysis and photodynamic therapy. Porphyrins and their derivatives are effective photosensitizers due to extended π-conjugated electronic structure, high molar absorption from visible to near-infrared spectrum, and high singlet oxygen quantum yields as well as chemical versatility. In this paper, we report a synthesis of self-assembled porphyrin nanoparticle photosensitizers using zinc meso-tetra(4-pyridyl)porphyrin (ZnTPyP) through a confined noncovalent self-assembly process. Scanning electron microscopy reveals formation of monodisperse cubic nanoparticles. UV-vis characterizations reveal that optical absorption of the nanoparticles exhibits a red shift due to noncovalent self-assembly of porphyrins, which not only effectively increase intensity of light absorption but also extend light absorption broadly covering visible light for enhanced photodynamic therapy. Electron spin-resonance spectroscopy (ESR) studies show the resultant porphyrin nanoparticles release a high yield of singlet oxygen. Nitric oxide (NO) coordinates to central metal Zn ions to form stabilized ZnTPyP@NO nanoparticles. We show that under light irradiation ZnTPyP@NO nanoparticles release highly reactive peroxynitrite molecules that exhibit enhanced antibacterial photodynamic therapy (APDT) activity. The ease of the synthesis of self-assembled porphyrin nanoparticles and light-triggered release of highly reactive moieties represent a completely different photosensitizer system for APDT application.

Novel Supramolecular Photocatalyst Based on Conjugation of Cucurbit[7]uril to Non‐Metallated Porphyrin for Electrophotocatalytic Hydrogen Generation from Water Splitting

“…However, the photocatalytic performance was found to be significantly enhanced in the case of composite TPP‐CB‐TiO 2 @Pt as compared to photocatalytic activities shown by TiO 2 @Pt and TPP‐CB@Pt. TPP‐CB‐TiO 2 @Pt produces hydrogen with an onset potential of −30 mV, TOF of 0.139 s −1 and the overpotential ( η @10) of 0.61 V. This is due to the synergistic influence of the combination of TPP‐CB and TiO 2 into one system . The polarization curves of FTO film electrodes under stable conditions are presented in Figure .…”

“…Due to its high molar absorptivity, dual‐absorption band feature and high charge carrier mobility, the electron migrations are believed to be facilitated, thus reducing the risks of photogenerated electron‐hole pairs recombination . In this regard, self‐assembled porphyrin derivatives in the form of nanoparticles, nanowires and nanorods as well as the composite of porphyrin‐based porous covalent organic framework with TiO 2 , porphyrin‐based imine gels and cobalt porphyrin‐polypyridyl surface coatings were utilized as visible‐light triggered photocatalysts in the hydrogen production from water splitting.…”

“…TPP-CB-TiO 2 @Pt produces hydrogen with an onset potential of À 30 mV, TOF of 0.139 s À 1 and the overpotential (η@10) of 0.61 V. This is due to the synergistic influence of the combination of TPP-CB and TiO 2 into one system. [11,12] The polarization curves of FTO film electrodes under stable conditions are presented in Figure 4. The potential required to reach these expected current densities (i. e. η @ 10 mA cm À 2 /V for HER) based on the geometric area (j g ) were compiled in a table shown in the supporting information (Table S1 and Figure S30-S31).…”

“…Due to its high molar absorptivity, dualabsorption band feature and high charge carrier mobility, the electron migrations are believed to be facilitated, thus reducing the risks of photogenerated electron-hole pairs recombination. [6b,c] In this regard, self-assembled porphyrin derivatives in the form of nanoparticles, nanowires and nanorods [9][10][11] as well as the composite of porphyrin-based porous covalent organic framework with TiO 2 [12] , porphyrinbased imine gels [13] and cobalt porphyrin-polypyridyl surface coatings [14] were utilized as visible-light triggered photocatalysts in the hydrogen production from water splitting.Herein, we report the synthesis of a novel photoactive supramolecular assembly that is based on the conjugation of cucurbit[7]uril hosts to free-base porphyrin core (TTP-4CB7) (Scheme 1) and also demonstrate the use of this assembly as a photocatalyst in hydrogen production from water splitting. Cucurbit[n]uril is a macrocycle and can be found in various sizes depending upon the number of glycol units which is composed of.…”

Harnessing the Photocatalytic Potential of Polypyrroles in Water through Nanointervension: Synthesis and Photophysical Evaluation of Biodegradable Polypyrrolic Nanoencapsulates

“…[10][11][12][13][14][15][16] The major drawback of these polypyrroles is that they are mostly hydrophobic in nature, which restricts their practical applicability. Multiple attempts have been made to improve the solubility of BODIPY and porphyrins through their conjugation/ adsorption on metal or metal oxide nanoparticles, [10,17,18] by preparing self-aggregated nanoparticles, [18] through encapsulation into polymers, etc. This property of polymers could make the water-insoluble polypyrroles to be active in an aqueous environment.…”