A gadolinium(III)-porphyrin based coordination polymer for colorimetric and fluorometric dual mode determination of ferric ions

A ruthenium-nickel metal-organic framework incorporating 2,2'-bipyridine- 5,5'-dicarboxylic acid for dual-mode electrochemiluminescence-fluorescence detection of ferric ions

A novel, low-toxicity Ru-Ni-BPY metal-organic framework (MOF) nanomaterial was developed and a simple and sensitive dual-mode "on-off" ferric ions (Fe3+) sensing platform based on this material constructed. The dual-mode detection method enabled cross-validation of the electrochemiluminescence (ECL) and fluorescent (FL) signals, enhancing accuracy and effectively minimizing errors. In linear ranges of 0.005-10 μM and 0.078-10 μM, Fe3+ can dramatically quench the ECL and FL signals of the Ru-Ni-BPY MOF, with quenching rates of 91.42% and 91.31%, respectively, and detection limits of 0.1 nM and 9.3 nM, respectively. This ECL method not only achieved efficient detection of Fe3+ in rat brain microdialysis fluid but also successfully enabled real-time FL detection of Fe3+ in nude mice. Therefore, this platform has great potential for applications in environmental protection, life sciences, and early disease diagnosis.

Controllable Synthesis of Hemoglobin-Metal Phosphate Organic-Inorganic Hybrid Nanoflowers and Their Applications in Biocatalysis

In recent years, organic-inorganic hybrid nanoflower technology has become an effective method for enzyme immobilization. Here, seven hierarchical flower-like hemoglobin-phosphate organic-inorganic hybrid nanomaterials (Hb-M3(PO4)2·nH2O HNFs) were synthesized through an improved universal one-pot wet-chemical method, with Ca2+, Mn2+, Fe2+, Co2+, Ni2+, Cu2+ and Zn2+ as inorganic components. In this synthesis process, the metal cations are successively involved in the coordination reaction with Hb and the metathesis reaction to generate phosphate precipitation. The coordination ability of metal cations and the generation rate of phosphate precipitations were evaluated, then the progress of the two chemical reactions was controlled synchronously by adjusting the phosphate buffer (PB) concentration, and finally a flower-like structure conducive to substrate diffusion and transport was obtained. Due to the conformational transformation of hemoglobin and the abundant Cu2+/Fe3+ active sites, the hemoglobin-Cu3(PO4)2·3H2O nanoflowers have extremely high catalytic activity, which is ∼14 times that of Hb. Importantly, this method is suitable for the monometallic-ionic, polymetallic-ionic and polyvalent metal-ion nanoflowers, which broadens the chemical composition and structural diversity of nanoflowers.

Spectrophotometric and Fluorometric Methods for the Determination of Fe(III) Ions in Water and Pharmaceutical Samples

Chemical sensors based on mesoporous silica nanotubes (MSNTs) for the quick detection of Fe(III) ions have been developed. The nanotubes' surface was chemically modified with phenolic groups by reaction of the silanol from the silica nanotubes surface with 3-aminopropyltriethoxysilane followed by reaction with 3-formylsalicylic acid (3-fsa) or 5-formylsalicylic acid (5-fsa) to produce the novel nanosensors. The color of the resultant 3-fsa-MSNT and 5-fsa-MSNT sensors changes once meeting a very low concentration of Fe(III) ions. Color changes can be seen by the naked eye and tracked with a smartphone or fluorometric or spectrophotometric techniques. Many experimental studies have been conducted to find out the optimum conditions for colorimetric and fluorometric determining of the Fe(III) ions by the two novel sensors. The response time, for the two sensors, that is necessary to achieve a steady spectroscopic signal was less than 15 s. The suggested methods were validated in terms of the lowest limit of detection (LOD), the lowest limit of quantification (LOQ), linearity, and precision according to International Conference on Harmonization (ICH) guidelines. The lowest limit of detection that was obtained from the spectrophotometric technique was 18 ppb for Fe(III) ions. In addition, the results showed that the two sensors can be used eight times after recycling using 0.1 M EDTA as eluent with high efficiency (90%). As a result, the two sensors were successfully used to determine Fe(III) in a variety of real samples (tap water, river water, seawater, and pharmaceutical samples) with great sensitivity and selectivity.

Lanthanide-tetrapyrrole complexes: synthesis, redox chemistry, photophysical properties, and photonic applications

Tetrapyrrole derivatives such as porphyrins, phthalocyanines, naphthalocyanines, and porpholactones, are highly stable macrocyclic compounds that play important roles in many phenomena linked to the development of life. Their complexes with lanthanides are known for more than 60 years and present breath-taking properties such as a range of easily accessible redox states leading to photo- and electro-chromism, paramagnetism, large non-linear optical parameters, and remarkable light emission in the visible and near-infrared (NIR) ranges. They are at the centre of many applications with an increasing focus on their ability to generate singlet oxygen for photodynamic therapy coupled with bioimaging and biosensing properties. This review first describes the synthetic paths leading to lanthanide-tetrapyrrole complexes together with their structures. The initial synthetic protocols were plagued by low yields and long reaction times; they have now been replaced with much more efficient and faster routes, thanks to the stunning advances in synthetic organic chemistry, so that quite complex multinuclear edifices are presently routinely obtained. Aspects such as redox properties, sensitization of NIR-emitting lanthanide ions, and non-linear optical properties are then presented. The spectacular improvements in the quantum yield and brightness of Yb^III-containing tetrapyrrole complexes achieved in the past five years are representative of the vitality of the field and open welcome opportunities for the bio-applications described in the last section. Perspectives for the field are vast and exciting as new derivatizations of the macrocycles may lead to sensitization of other Ln^III NIR-emitting ions with luminescence in the NIR-II and NIR-III biological windows, while conjugation with peptides and aptamers opens the way for lanthanide-tetrapyrrole theranostics.

Conjugated Coordination Porphyrin-based Nanozymes for Photo-/Sono-Augmented Biocatalytic and Homologous Tumor Treatments

Porphyrin-based nanozymes (Porzymes) have shown promising application potential to fight against tumors using catalytically generated reactive oxygen species from the excessively produced H2O2 in the tumor microenvironment. However, the low coordination porphyrin (CP) loading ratio, difficult controllable nanostructure, low bioavailability, and low biocatalytic activities of current established Porzymes have severely limited their antitumor applications. Here, a novel malignant melanoma cell membrane-coated Pd-based CP nanoplatform (Trojan Porzymes) has been synthesized for biocatalytic and homologous tumor therapies. The Trojan Porzymes exhibit a high CP loading ratio, uniform nanoscale size, single-atom nanostructure, homologous targeted ability, and high-efficiency photo/sono-augmented biocatalytic activities. The enzyme-like biocatalytic experiments display that the Trojan Porzymes can generate abundant •OH via chemodynamic path and 1O2 via visible light or ultrasound excitation. Then we demonstrate that the Trojan Porzymes show homologous targeting ability to tumor cells and can achieve efficient accumulation and long-term retention in cancer tissues. Our in vivo data further disclose that the photo/sono-assisted chemodynamic therapies can significantly augment the treatment efficiency of malignant melanoma. We believe that our work will afford a new biocatalytic and homologous strategy for future clinical malignant melanoma treatments, which may inspire and guide more future studies to develop individualized biomedicine in precise tumor therapies.

Bio-multifunctional noncovalent porphyrin functionalized carbon-based nanocomposite

Herein, in a one-pot method, the reduced graphene oxide layers with the assistance of multiwalled carbon nanotubes were decorated to provide a suitable space for the in situ growth of CoNi₂S₄, and the porphyrins were incorporated into the layers as well to increase the sensitivity of the prepared nanostructure. The prepared nanocomposite can establish π-π interactions between the genetic material and on the surface of porphyrin rings. Also, hydrogen bonds between genetic domains and the porphyrin' nitrogen and the surface hydroxyl groups are probable. Furthermore, the potential donor-acceptor relationship between the d⁷ transition metal, cobalt, and the genetic material provides a suitable way to increase the interaction and gene loading , and transfections. The reason for this phenomenon was optimized to increase the EGFP by up to 17.9%. Furthermore, the sensing ability of the nanocomposite towards H₂O₂ was investigated. In this regard, the limit of detection of the H₂O₂ obtained 10 µM. Also, the in situ biosensing ability in the HEK-293 and PC12 cell lines was evaluated by the addition of PMA. The nanocomposite showed the ability to detect the released H₂O₂ after adding the minimum amount of 120 ng/mL of the PMA.

Adhesion enhancement via the synergistic effect of metal–ligand coordination and supramolecular host–guest interactions in luminescent hydrogels

We report an approach to achieve adhesion enhancement via the synergistic effect of metal–ligand coordination and supramolecular host–guest interactions in luminescent hydrogels without affecting their luminescence behavior.

Recent Advances in Porphyrin-Based Materials for Metal Ions Detection

Porphyrins have planar and conjugated structures, good optical properties, and other special functional properties. Owing to these excellent properties, in recent years, porphyrins and their analogues have emerged as a multifunctional platform for chemical sensors. The rich chemistry of these molecules offers many possibilities for metal ions detection. This review mainly discusses two types of molecular porphyrin and porphyrin composite sensors for metal ions detection, because porphyrins can be functionalized to improve their functional properties, which can introduce more chemical and functional sites. According to the different application materials, the section of porphyrin composite sensors is divided into five sub-categories: (1) porphyrin film, (2) porphyrin metal complex, (3) metal–organic frameworks, (4) graphene materials, and (5) other materials, respectively.