A sensitive A3B porphyrin nanomaterial for CO2 detection

Excellent Cooperation between Carboxyl-Substituted Porphyrins, k-Carrageenan and AuNPs for Extended Application in CO2 Capture and Manganese Ion Detection

Significant tasks of the presented research are the development of multifunctional materials capable both to detect/capture carbon dioxide and to monitor toxic metal ions from waters, thus contributing to maintaining a sustainable and clean environment. The purpose of this work was to synthesize, characterize (NMR, FT-IR, UV-Vis, Fluorescence, AFM) and exploit the optical and emission properties of a carboxyl-substituted A3B porphyrin, 5-(4-carboxy-phenyl)-10,15,20-tris-(4-methyl-phenyl)–porphyrin, and based on it, to develop novel composite material able to adsorb carbon dioxide. This porphyrin-k-carrageenan composite material can capture CO2 in ambient conditions with a performance of 6.97 mmol/1 g adsorbent. Another aim of our research was to extend this porphyrin- k-carrageenan material’s functionality toward Mn2+ detection from polluted waters and from medical samples, relying on its synergistic partnership with gold nanoparticles (AuNPs). The plasmonic porphyrin-k-carrageenan-AuNPs material detected Mn2+ in the range of concentration of 4.56 × 10−5 M to 9.39 × 10−5 M (5–11 mg/L), which can be useful for monitoring health of humans exposed to polluted water sources or those who ingested high dietary manganese.

SnSe2-Zn-Porphyrin Nanocomposite Thin Films for Threshold Methane Concentration Detection at Room Temperature

Nanocomposite thin films, sensitive to methane at the room temperature (25–30 °C), have been prepared, starting from SnSe2 powder and Zn(II)-5,10,15,20-tetrakis-(4-aminophenyl)- -porphyrin (ZnTAPP) powder, that were fully characterized by XRD, UV-VIS, FT-IR, Nuclear Magnetic Resonance (1H-NMR and 13C-NMR), Atomic Force Microscopy (AFM), SEM and Electron Paramagnetic Resonance (EPR) techniques. Film deposition was made by drop casting from a suitable solvent for the two starting materials, after mixing them in an ultrasonic bath. The thickness of these films were estimated from SEM images, and found to be around 1.3 μm. These thin films proved to be sensitive to a threshold methane (CH4) concentration as low as 1000 ppm, at a room temperature of about 25 °C, without the need for heating the sensing element. The nanocomposite material has a prompt and reproducible response to methane in the case of air, with 50% relative humidity (RH) as well. A comparison of the methane sensing performances of our new nanocomposite film with that of other recently reported methane sensitive materials is provided. It is suitable for signaling gas presence before reaching the critical lower explosion limit concentration of methane at 50,000 ppm.

Hybrid Materials Based on Silica Matrices Impregnated with Pt-Porphyrin or PtNPs Destined for CO2 Gas Detection or for Wastewaters Color Removal

Multifunctional hybrid materials with applications in gas sensing or dye removal from wastewaters were obtained by incorporation into silica matrices of either Pt(II)-5,10,15,20-tetra-(4-allyloxy-phenyl)-porphyrin (PtTAOPP) or platinum nanoparticles (PtNPs) alone or accompanied by 5,10,15,20-tetra-(4-allyloxy-phenyl)-porphyrin (TAOPP). The tetraethylorthosilicate (TEOS)-based silica matrices were obtained by using the sol-gel method performed in two step acid-base catalysis. Optical, structural and morphological properties of the hybrid materials were determined and compared by UV-vis, fluorescence and FT-IR spectroscopy techniques, by atomic force microscopy (AFM) and high resolution transmission electron microscopy (HRTEM) and by Brunauer–Emmett–Teller (BET) analysis. PtTAOPP-silica hybrid was the most efficient material both for CO₂ adsorption (0.025 mol/g) and for methylene blue adsorption (7.26 mg/g) from wastewaters. These results were expected due to both the ink-bottle mesopores having large necks that exist in this hybrid material and to the presence of the porphyrin moiety that facilitates chemical interactions with either CO₂ gas or the dye molecule. Kinetic studies concerning the mechanism of dye adsorption demonstrated a second order kinetic model, thus it might be attributed to both physical and chemical processes.

High-effective reactive oxygen species inducer based on Mn-tetraphenylporphyrin loaded PLGA nanoparticles in binary catalyst therapy

The mechanisms of binary catalyst therapy (BCT) and photodynamic therapy (PDT) are based on the formation of reactive oxygen species (ROS). This ROS formation results from specific chemical reactions. In BCT, light exposure does not necessarily initiate ROS formation and BCT application is not limited to regions of tissues that are accessible to illumination like photodynamic therapy (PDT). The principle of BCT is electron transition, resulting in the interaction of a transition metal complex (catalyst) and substrate molecule. Mn^III- tetraphenylporphyrin chloride (MnClTPP) in combination with an ascorbic acid (AA) has been proposed as an appropriate candidate for cancer treatment regarding the active agents in BCT. The goal of this study was to determine whether MnClTPP in combination with AA would be a promising agent for BCT. The problem of used MnClTPP's, low solubility in water, was solved by MnClTPP loading into PLGA matrix. H₂O₂ produced during AA decomposition oxidized MnClTPP to high-reactive oxo-Mn^V species. MnClTPP in presence AA leads to the production of excessive ROS levels in vitro. ROS are mainly substrates of catalase and superoxide dismutase (H₂O₂ and O₂^●-). SOD1 and catalase were identified as the key players of the MnClTPP ROS-induced cell defense system. The cytotoxicity of MnClTPP-loaded nanoparticles (NPs) was greatly increased in the presence of specific catalase inhibitor (3-amino-1,2,4-triazole (3AT)) and superoxide dismutase 1 (SOD1) inhibitor (diethyldithiocarbamate (DDC)). Cell death resulted from the combined activation of caspase-dependent (caspase 3/9 system) and independent pathways, namely the AIF translocation to nuclei. Preliminary acute toxicity and in vivo anticancer studies have been revealed the safe and potent anticancer effect of PLGA-entrapped MnClTPP in combination with AA. The findings indicate that MnClTPP-loaded PLGA NPs are promising agents for BCT.

Porphyrins in troubled times: a spotlight on porphyrins and their metal complexes for explosives testing and CBRN defense

A critical perspective on (metallo)porphyrins in security-related applications: the past, present and future of explosives detection, CBRN defense, and beyond.

Trace Oxygen Sensitive Material Based on Two Porphyrin Derivatives in a Heterodimeric Complex

The successful preparation of a novel dimer complex formed between 5,10,15,20-tetrakis(3,4-dimethoxyphenyl)-porphyrin Fe(III) chloride and (5,10,15,20-tetraphenylporphinato) dichlorophosphorus(V) chloride using the well-known reactivity of the P-X bond is reported. The obtained complex was characterized by UV-vis, Fourier transform infrared spectroscopy (FT-IR), fluorescence, ¹H-NMR, ¹³C-NMR, and ³¹P-NMR spectroscopic techniques and also by additional Heteronuclear Single Quantum Coherence (HSQC) and Heteronuclear Multiple Bond Correlation (HMBC) experiments in order to correctly assign the NMR signals. Scanning electron microscopy (SEM) and EDX quantifications completed the characterizations. This novel porphyrin dimer complex demonstrated fluorescence sensing of H₂O₂ in water for low oxygen concentrations in the range of 40-90 µM proving medical relevance for early diagnosis of diseases such as Alzheimer's, Parkinson's, Huntington's, and even cancer because higher concentrations of H₂O₂ than 50 μM are consideredcytotoxic for life. Due to its optical properties, this novel metalloporphyrin-porphyrin based complex is expected to show PDT and bactericidal activity under visible-light irradiation.

Porphyrinoids for Chemical Sensor Applications

Porphyrins and related macrocycles have been intensively exploited as sensing materials in chemical sensors, since in these devices they mimic most of their biological functions, such as reversible binding, catalytic activation, and optical changes. Such a magnificent bouquet of properties allows applying porphyrin derivatives to different transducers, ranging from nanogravimetric to optical devices, also enabling the realization of multifunctional chemical sensors, in which multiple transduction mechanisms are applied to the same sensing layer. Potential applications are further expanded through sensor arrays, where cross-selective sensing layers can be applied for the analysis of complex chemical matrices. The possibility of finely tuning the macrocycle properties by synthetic modification of the different components of the porphyrin ring, such as peripheral substituents, molecular skeleton, coordinated metal, allows creating a vast library of porphyrinoid-based sensing layers. From among these, one can select optimal arrays for a particular application. This feature is particularly suitable for sensor array applications, where cross-selective receptors are required. This Review briefly describes chemical sensor principles. The main part of the Review is divided into two sections, describing the porphyrin-based devices devoted to the detection of gaseous or liquid samples, according to the corresponding transduction mechanism. Although most devices are based on porphyrin derivatives, seminal examples of the application of corroles or other porphyrin analogues are evidenced in dedicated sections.