Perylene Bisimide Aggregates as Probes for Subnanomolar Discrimination of Aromatic Biogenic Amines

A perylene-based fluorescent probe for highly efficient SDS detection

Sodium dodecyl sulfate (SDS) is widely used in numerous household products and pharmaceuticals due to its excellent water solubility, emulsification, foaming, and dispersing properties. However, the extensive use of SDS has made it a significant environmental pollutant, posing a great threat to aquatic ecosystems. Therefore, developing a rapid, efficient, and sensitive probe for detecting SDS in aqueous environments is crucial. In this study, we present a cationic imidazolium-conjugated perylene bisimide (PBI) compound, as an effective probe for detecting SDS in aqueous media. The probe exhibits a distinct color change from dark pink to light pink upon interaction with SDS, making it a simple yet powerful tool for naked-eye detection. Moreover, the strong electrostatic interaction between the positively charged PBI compound and the negatively charged sulfate group in SDS leads to the formation of closely packed molecular aggregates. This results in significant quenching of fluorescence emission, enabling the detection of SDS at micromolar concentrations. We further demonstrate the practical application of PBI compound for sensitive and selective fluorometric detection of SDS in home-care items and tap water samples. These findings highlight the potential of such compounds as versatile tools for both environmental monitoring and product safety applications involving sulfate-containing species.

A simple protocol for the synthesis of perylene bisimides from perylene tetracarboxylic dianhydride

Perylene bisimides are highly attractive polycyclic aromatic hydrocarbons due to their photostability associated to unique and characteristic photochemical properties. They have been widely used for analytical purposes, despite the hydrophobicity of most of these compounds. The ring substitution pattern plays an important role in fine-tuning the physicochemical properties that govern solubility and aggregation. In this work, a selection of perylene bisimides were prepared from the reaction of perylenetetracarboxylic dianhydride with α-amino acids or primary aliphatic and aromatic amines. These molecules were obtained in good yield by a simple synthetic protocol based on the use of imidazole as a green solvent and avoiding the need for complex purification methods, a major advantage for future applications. Functionalization of the exocyclic substituent can also be performed and was exemplified by the incorporation of the maleimide and anthraquinone moieties.

NDI based C2-symmetric Chiral Supramolecular Hydrogels Towards Enhanced Conductivity

To comprehend the significance of improved conductive properties in C2-symmetric hydrogels, it is vital to investigate how non-gelating achiral functional group isomers influence the conductivity of such supramolecular hydrogels, whereas understanding the major driving forces behind this regulatory process is first and foremost. Herein, we report a hydrogel system containing tryptophan-conjugated NDI as the backbone (L/D-NTrp), enabling effective supramolecular assembly with the bipyridyl functional group isomers. This co-assembly behavior results in materials with exceptional mechanical properties and high conductivities, surpassing most previously reported C2-symmetrical hydrogels, as well as the ability to form controlled morphologies. Notably, the co-hydrogels displayed an eight-fold increase in mechanical strength, making them more robust and resistant to deformation compared to the original gel. Additionally, all hydrogels exhibited favorable electrical conductivity, with the co-assembled hydrogels showcasing notable performance, making them a promising candidate for use in electronic devices and sensors. This report lays the foundation for further investigation into the properties and potential applications of L/D-NTrp compound in the range of fields, including drug delivery, tissue engineering, and electronics.

Highly sensitively detection of amine vapors released during shrimp spoilage by fluorescent molecules locked in covalent organic frameworks

The fluorescent sensors allow sensitive detection of amine vapors for assessing the safety and quality of seafood products. However, high diffusion resistance and insufficient recognition sites usually limit the sensitivity of the sensors. Here, we employed an emulsion-confined assembly strategy to uniform encapsulate fluorescent molecules perylene diimide (PDI) molecules into covalent organic frameworks (COFs) to achieve ultrasensitive detection of amine vapors. The detection mechanism is based on the photoinduced electron transfer from amine to the excited PDI. This method exhibits a broad linear detection range from 8 ppb to 800 ppm and the limit of detection reaches as low as 1.2 ppb. The real-time detection of the amine vapors produced during shrimp spoilage is successfully achieved with excellent performance. This provides a versatile method for the on-demand synthesis of functional materials with high fluorescence properties for the development of chemical sensors via encapsulating different fluorescent molecules into COFs.

Luminescence-based detection and identification of illicit drugs

Luminescence-based sensing is capable of being used for the sensitive, rapid, and in some cases selective detection of chemicals. Furthermore, the method is amenable to incorporation into handheld low-power portable detectors that can be used in the field. Luminescence-based detectors are now commercially available for explosive detection with the technology built on a strong foundation of science. In contrast, there are fewer examples of luminescence-based detection of illicit drugs, despite the pervasive and global challenge of combating their manufacture, distribution and consumption and the need for handheld detection systems. This perspective describes the relatively nascent steps that have been reported in the use of luminescent materials for the detection of illicit drugs. Much of the published work has focused on detection of illicit drugs in solution with less work on vapour detection using thin luminescent sensing films. The latter are better suited for handheld sensing devices and detection in the field. Illicit drug detection has been achieved via different mechanisms, all of which change the luminescence of the sensing material. These include photoinduced hole transfer (PHT) leading to quenching of the luminescence, disruption of Förster energy transfer between different chromophores by a drug, and chemical reaction between the sensing material and a drug. The most promising of these is PHT, which can be used for rapid and reversible detection of illicit drugs in solution and film-based sensing of drugs in the vapour phase. However, there are still significant knowledge gaps, for example, how vapours of illicit drugs interact with the sensing films, and how to achieve selectivity for specific drugs.

Concepts and principles of self-n-doping in perylene diimide chromophores for applications in biochemistry, energy harvesting, energy storage, and catalysis

Self-doping is an essential method of increasing carrier concentrations in organic electronics that eliminates the need to tailor host-dopant miscibility, a necessary step when employing molecular dopants. Self-n-doping can be accomplished using amines or ammonium counterions as an electron source, which are being incorporated into an ever-increasingly diverse range of organic materials spanning many applications. Self-n-doped materials have demonstrated exemplary and, in many cases, benchmark performances in a variety of applications. However, an in-depth review of the method is lacking. Perylene diimide (PDI) chromophores are an important mainstay in the semiconductor literature with well-known structure-function characteristics and are also one of the most widely utilized scaffolds for self-n-doping. In this review, we describe the unique properties of self-n-doped PDIs, delineate structure-function relationships, and discuss self-n-doped PDI performance in a range of applications. In particular, the impact of amine/ammonium incorporation into the PDI scaffold on doping efficiency is reviewed with regard to attachment mode, tether distance, counterion selection, and steric encumbrance. Self-n-doped PDIs are a unique set of PDI structural derivatives whose properties are amenable to a broad range of applications such as biochemistry, solar energy conversion, thermoelectric modules, batteries, and photocatalysis. Finally, we discuss challenges and the future outlook of self-n-doping principles.

Evolution of Supramolecular Systems Towards Next-Generation Biosensors

Supramolecular materials, which rely on dynamic non-covalent interactions, present a promising approach to advance the capabilities of currently available biosensors. The weak interactions between supramolecular monomers allow for adaptivity and responsiveness of supramolecular or self-assembling systems to external stimuli. In many cases, these characteristics improve the performance of recognition units, reporters, or signal transducers of biosensors. The facile methods for preparing supramolecular materials also allow for straightforward ways to combine them with other functional materials and create multicomponent sensors. To date, biosensors with supramolecular components are capable of not only detecting target analytes based on known ligand affinity or specific host-guest interactions, but can also be used for more complex structural detection such as chiral sensing. In this Review, we discuss the advancements in the area of biosensors, with a particular highlight on the designs of supramolecular materials employed in analytical applications over the years. We will first describe how different types of supramolecular components are currently used as recognition or reporter units for biosensors. The working mechanisms of detection and signal transduction by supramolecular systems will be presented, as well as the important hierarchical characteristics from the monomers to assemblies that contribute to selectivity and sensitivity. We will then examine how supramolecular materials are currently integrated in different types of biosensing platforms. Emerging trends and perspectives will be outlined, specifically for exploring new design and platforms that may bring supramolecular sensors a step closer towards practical use for multiplexed or differential sensing, higher throughput operations, real-time monitoring, reporting of biological function, as well as for environmental studies.

Review on application of perylene diimide (PDI)-based materials in environment: Pollutant detection and degradation

Environment pollution is getting serious and various poisonous contaminants with chemical durability, biotoxicity and bioaccumulation have been widespreadly discovered in municipal wastewaters and surface water. The detection and removal of pollutants show great significance for the protection of human health and other organisms. Due to its distinctive physical and chemical properties, perylene diimide (PDI) has received widespread attention from different research fields, especially in the area of environment. In this review, a comprehensive summary of the development of PDI-based materials in fluorescence detection and advanced oxidation technology for environment was introduced. Firstly, we chiefly presented the recent progress about the synthesis of PDI and PDI-based nanomaterials. Then, their application in fluorescence detection for environment was presented and categorized, principally including the detection of heavy metal ions, harmful anions and organic contaminants in the environment. In addition, the application of PDI and PDI-based materials in different advanced oxidation technologies for environment, such as photocatalysis, photoelectrocatalysis, Fenton and Fenton-like reaction and persulfate activation, was also summarized. At last, the challenges and future prospects of PDI-based materials in environmental applications were discussed. This review focuses on presenting the practical applications of PDI and PDI-based materials as fluorescent probes or catalysts (especially photocatalysts) in the detection of hazardous substances or catalytic elimination of organic contaminants. The contents are aimed at supplying the researchers with a deeper understanding of PDI and PDI-based materials and encouraging their further development in environmental applications.

Highly selective and sensitive colorimetric/fluorometric dual mode detection of relevant biogenic amines

Biogenic amines are involved in physiological roles in living organisms, but their excessive production or intake can induce undesired toxicological effects. As biogenic amines can be found in the process of food spoilage, they are considered an indicator of food quality and freshness, and their detection is of crucial importance in food safety. In this contribution, we report the fast and direct colorimetric and fluorometric sensing of biogenic amines by means of a dinuclear Zn(ii) Schiff-base complex. The selective and sensitive detection involves the formation of stable adducts between the dinuclear complex, acting as the Lewis acidic molecular tweezer, and biogenic di- or polyamines. The selectivity towards biogenic amines, even in the presence of common aliphatic, primary, secondary, or tertiary monoamines, heterocyclic amines, and amino acids, is demonstrated by competitive experiments. The quantitation of histamine in a fish matrix is easily achieved using a standard extraction procedure followed by simple colorimetric or fluorometric measurements.

Paramagnetic Functionalization of Biocompatible Scaffolds for Biomedical Applications: A Perspective

The burst of research papers focused on the tissue engineering and regeneration recorded in the last years is justified by the increased skills in the synthesis of nanostructures able to confer peculiar biological and mechanical features to the matrix where they are dispersed. Inorganic, organic and hybrid nanostructures are proposed in the literature depending on the characteristic that has to be tuned and on the effect that has to be induced. In the field of the inorganic nanoparticles used for decorating the bio-scaffolds, the most recent contributions about the paramagnetic and superparamagnetic nanoparticles use was evaluated in the present contribution. The intrinsic properties of the paramagnetic nanoparticles, the possibility to be triggered by the simple application of an external magnetic field, their biocompatibility and the easiness of the synthetic procedures for obtaining them proposed these nanostructures as ideal candidates for positively enhancing the tissue regeneration. Herein, we divided the discussion into two macro-topics: the use of magnetic nanoparticles in scaffolds used for hard tissue engineering for soft tissue regeneration.

A novel and efficient chromophore reaction based on a lactam-fused aza-BODIPY for polyamine detection

Polyamines (such as spermine, spermidine) play important roles in biomedical and food field. The elevated polyamines have been proposed to serve as target analytes for monitoring meat spoilage. Because of structural similarity and low concentration of polyamines in real samples, it is exceedingly challenging to design and develop sensitive probes for visual detection of polyamines. To address this issue, a highly efficient probe was reported based on a newly developed chromophore reaction between lactam-fused aza-BODIPY (abbreviation: LAB) and polyamines by virtue of unique multiple amino groups character of polyamines. This chromophore reaction includes a kinetic-controllable reaction of a B-N bond cleavage by polyamines followed by a fast hydrolysis reaction to yield much smaller conjugated molecules. With 130 nm hypsochromic shift of the absorption peak and up to 99% fluorescence quenching within 1 min, LAB can be used as a highly sensitive fluorescent probe for detection of polyamines solution and monitoring fish spoilage with synchronous colorimetric and fluorescent changes.

Applications of Photoinduced Phenomena in Supramolecularly Arranged Phthalocyanine Derivatives: A Perspective

This review focuses on the description of several examples of supramolecular assemblies of phthalocyanine derivatives differently functionalized and interfaced with diverse kinds of chemical species for photo-induced phenomena applications. In fact, the role of different substituents was investigated in order to tune peculiar aggregates formation as well as, with the same aim, the possibility to interface these derivatives with other molecular species, as electron donor and acceptor, carbon allotropes, cyclodextrins, protein cages, drugs. Phthalocyanine photo-physical features are indeed really interesting and appealing but need to be preserved and optimized. Here, we highlight that the supramolecular approach is a versatile method to build up very complex and functional architectures. Further, the possibility to minimize the organization energy and to facilitate the spontaneous assembly of the molecules, in numerous examples, has been demonstrated to be more useful and performing than the covalent approach.

A review on chemical and electrochemical methodologies for the sensing of biogenic amines

Biogenic amines (BA) are biomolecules of low molecular weight with organic basic functionalities (amine group) that are formed by the microbial decarboxylation of amino acids of fermented food/beverages. Hence BAs are an important indicator in estimating the freshness and quality of meat, seafood, and industrial food products with high protein content. The reaction of BAs with nitrites available in certain meat products forms nitrosoamine, a carcinogenic compound. Hence BAs are in general considered to be a food hazard and monitoring the level of BAs in food samples becomes crucial as their high concentrations may lead to health problems. This review offers an overview of the available chemical and electrochemical methods that are typically used for the sensing of BAs in food samples. Certain compounds are known to selectively interact with BAs via chemical or non-covalent interactions and these interactions are often accompanied by fluorescence or visible color changes (sometimes visual detection) that could be monitored/assessed using a fluorescence spectrophotometer or UV-vis spectrophotometer (colorimetric methods). The colorimetric methods are limited by sensitivity and selectivity as they are based on straight-forward chemical reactions. In the case of electrochemical sensing of BAs, mediators are often used which undergo oxidation/reduction to produce intermediates that could interact with BAs accompanied by changes in their electrochemical potential. Overall, this review summarizes the available chemical and electrochemical strategies towards the sensing of BAs with a discussion on further prospects.

Perylene pigment wastewater treatment by fenton-enhanced biological process

Polycyclic aromatic hydrocarbons (PAHs) are regarded as priority pollutants owing to their toxic, mutagenic and carcinogenic characteristics. Perylene is a kind of 5-ring PAH with biological toxicity, and classified as a class III carcinogen by the World Health Organization (WHO). Nowadays, some of its derivatives are often used as industrial pigments. Hence, urgent attention is highly needed to develop new and improved techniques for PAHs and their derivatives removal from the environment. In this study, Fenton oxidation process was hybridized with the biological (anaerobic and aerobic) treatments for the removal of perylene pigment from wastewater. The experiments were carried out by setting Fenton treatment system before and between the biological treatments. The biological results showed that COD removal efficiency reached 60% during 24 h HRT with an effluent COD concentration of 1567.78 mg/L. After the HRT increased to 48 h, the COD removal efficiency was slightly increased (67.9%). However, after combining Fenton treatment with biological treatment (Anaerobic-Fenton-Aerobic), the results revealed over 85% COD removal efficiency and the effluent concentration less than 600 mg/L which was selected as the better treatment configuration for the biological and chemical combined system. The microbial community analysis of activated sludge was carried out with high-throughput Illumina sequencing platform and results showed that Pseudomonas, Citrobacter and Methylocapsa were found to be the dominant genera detected in aerobic and anaerobic reactors. These dominant bacteria depicted that the community composition of the reactors for treating perylene pigments wastewater were similar to that of the soil contaminated by PAHs and the activated sludge from treating PAHs wastewater. Economic analysis results revealed that the reagent cost was relatively cheap, amounting to 10.64 yuan per kilogram COD. This study vividly demonstrated that combining Fenton treatment with biological treatment was efficient and cost-effective.

Wet Synthesis of Elongated Hexagonal ZnO Microstructures for Applications as Photo-Piezoelectric Catalysts

It is well known that energetic demand and environmental pollution are strictly connected; the side products of vehicle and industrial exhausts are considered extremely dangerous for both human and environmental health. In the last years, the possibility to simultaneously photo-degrade water dissolved pollutants by means of ZnO nanostructures and to use their piezoelectric features to enhance the photo-degradation process has been investigated. In the present contribution, an easy and low-cost wet approach to synthetize hexagonal elongated ZnO microstructures in the wurtzite phase was developed. ZnO performances as photo-catalysts, under UV-light irradiation, were confirmed on water dissolved methylene blue dye. Piezoelectric responses of the synthetized ZnO microstructures were evaluated, as well, by depositing them into films onto flexible substrates, and a home-made layout was developed, in order to stimulate the ZnO microstructures deposited on solid supports by means of mechanical stress and UV photons, simultaneously. A relevant increment of the photo-degradation efficiency was observed when the piezopotential was applied, proposing the present approach as a completely eco-friendly tool, able to use renewable energy sources to degrade water solved pollutants.

Visible light promoted porphyrin-based metal-organic adduct

Supramolecular adducts formed by a commercial porphyrin derivative and silver nanoparticles have been obtained using exclusively light as an external trigger that is able to promote the formation of the plasmonic nanostructures. In particular, a water-soluble porphyrin, i.e. tetrakis(4-carboxyphenyl)porphyrin, has been used. It has been thoroughly characterized by means of UV-vis and fluorescence spectroscopy in order to explain its peculiar behavior when illumined with visible photons. Herein we demonstrate that, by means of light illumination, it is possible to tune the porphyrin aggregation state. Furthermore, when the monomeric form of the organic macrocycle is induced and a controlled amount of AgNO[Formula: see text] is simultaneously dissolved, it is possible to promote the formation of silver nanostructures using visible light. The proposed approach allowed porphyrin derivatives/Ag nanoparticles hybrid nanostructures to be obtained without using a chemical reducing agent: the porphyrin derivative simultaneously acts as reducing agent when irradiated by visible light and as a capping agent for the silver nanostructures. The organic/inorganic adduct was characterized by means of steady-state fluorescence that highlights a strong energetic or electronic communication between the two species. XRD and SEM investigations evidence that silver nanoparticles are formed without using any reducing agent.

Cellulose-based fluorescent sensor for visual and versatile detection of amines and anions

It is practical and challenging to construct ultrasensitive and multi-responsive sensors for visual and real-time monitoring of the environment. Herein, a cellulose-based multi-responsive fluorescent sensor (Phen-MDI-CA) is fabricated, and realizes a visual and ultrasensitive detection of not only various amines but also three anions based on the change of the fluorescence and/or visible colors. Once exposure to various amines in both the solution and vapor state, the Phen-MDI-CA solution and test paper exhibit different fluorescence colors, which can be used to distinguish triethylamine, ethylenediamine, methylamine, aniline, hydrazine and pyrrolidine from other amines. Moreover, via combining the Phen-MDI-CA with the Phen-MDI-CA/malachite green ratiometric system, phosphate (PO₄^3-), carbonate (CO₃^2-) and borate (B₄O₇^2-) can be visually and accurately recognized depending on the change of the visible and fluorescence colors. In fluorescent mode, the LOD for B₄O₇^2-, PO₄^3- and CO₃^2- ions is as low as 0.18 nmol, 0.69 nmol and 0.86 nmol, respectively. Significantly, the Phen-MDI-CA can readily make a qualitative and quantitative detection of B₄O₇^2-, PO₄^3- and CO₃^2- anions in the mixture of anions. The state-of-the-art responsive behavior of Phen-MDI-CA originates from the amplification effect of cellulose polymer chain and the differentiated interactions between the sensor and analytes.

Tubular Perylene Bisimide Macrocycles for the Recognition of Geometrical Isomers of Azobenzenes

Perylene bisimide-based materials are good candidates for photosensitive applications. Herein, we report synthesis, characterization, and complexation studies of perylene bisimide macrocycles obtained through bayside coupling. The isomeric macrocycles incorporated with interesting optical properties and tubular-shaped cavities are able to recognize geometric isomers of azobenzenes and aromatic amines. Such selective recognition is useful toward developing potential sensors for interesting isomeric pairs in the future.

Supramolecular Chiral Discrimination of D-Phenylalanine Amino Acid Based on a Perylene Bisimide Derivative

The interaction between homochiral substituted perylene bisimide (PBI) molecule and the D enantiomer of phenylalanine amino acid was monitored. Spectroscopic transitions of PBI derivative in aqueous solution in the visible range were used to evaluate the presence of D-phenylalanine. UV-visible, fluorescence, FT-IR, and AFM characterizations showed that D-phenylalanine induces significant variations in the chiral perylene derivative aggregation state and the mechanism is enantioselective as a consequence of the 3D analyte structure. The interaction mechanism was further investigated in presence of interfering amino acid (D-serine and D-histidine) confirming that both chemical structure and its 3D structure play a crucial role for the amino acid discrimination. A D-phenylalanine fluorescence sensor based on perylene was proposed. A limit of detection (LOD) of 64.2 ± 0.38 nM was calculated in the range 10-7-10-5 M and of 1.53 ± 0.89 μM was obtained in the range 10-5 and 10-3 M.

Perylene Diimide-Based Fluorescent and Colorimetric Sensors for Environmental Detection

Perylene tetracarboxylic diimide (PDI) and its derivatives exhibit excellent thermal, chemical and optical stability, strong electron affinity, strong visible-light absorption and unique fluorescence on/off features. The combination of these features makes PDIs ideal molecular frameworks for development in a broad range of sensors for detecting environmental pollutants such as heavy metal ions (e.g., Cu2+, Cd2+, Hg2+, Pd2+, etc.), inorganic anions (e.g., F-, ClO4-, PO4-, etc.), as well as poisonous organic compounds such as nitriles, amines, nitroaromatics, benzene homologues, etc. In this review, we provide a comprehensive overview of the recent advance in research and development of PDI-based fluorescent sensors, as well as related colorimetric and multi-mode sensor systems, for environmental detection in aqueous, organic or mixed solutions. The molecular design of PDIs and structural optimization of the sensor system (regarding both sensitivity and selectivity) in response to varying analytes are discussed in detail. At the end, a perspective summary is provided covering both the key challenges and potential solutions for the future development of PDI-based optical sensors.

Aggregation Induced Emission Switching Based Ultrasensitive Ratiometric Detection of Biogenic Diamines Using a Perylenediimide-Based Smart Fluoroprobe

In recent years, the widely explored phenomenon "aggregation-induced emission (AIE)" has played a crucial role in the development of luminescent materials for light-emitting applications. In the same direction, the contribution of its sister concept "AIE switching" has been impressive. In comparison, the application of this concept in the field of biosensing or bioimaging is still in its infancy. Therefore, to shed light into the sensing of bioanalytes, we have developed a new perylenediimide (PDI)-based small fluorescent probe, benzoannulated PDI (Bp(Im)₂MA), that selectively detects diamines and biogenic amines (BAs) in solution via an "AIE-switching" phenomenon. The synthesized probe containing the bay-annulated anhydride moiety exhibits strong cyan emission in solution. In the mechanism, we have shown that the terminal free amine group of BAs readily reacts with a highly reactive anhydride moiety, which opens the cyclic anhydride moiety. In the open conformation, the free amine group along with a carboxylate group modulates the polarity of the system strikingly. Because of this induced polarity, the monomer of Bp(Im)₂MA-BAs conjugate aggregated in solution, thereby exhibiting a significant change in emission property in solution. This method may also be called a very simple and straightforward "naked eye" detection of BAs in solution, with a nanomolar detection limit. A detailed spectroscopic and microscopic investigation demonstrated the existence of the aggregated state. As the reporter dye also emits strongly in the solid state (yellowish orange), it therefore instantly made vapor-phase detection of BAs feasible. Finally, this vapor-phase detection of BAs by the probe was applied very effectively in the determination of spoilage of raw fish.