Sensitive Fluorescence Detection of Phthalates by Suppressing the Intramolecular Motion of Nitrophenyl Groups in Porous Crystalline Ribbons

Electronic Effect Driven Specific and Sensitive Recognition toward GHB

Precise detection of a trace substance that intrinsically possesses weak chemical activity and less-distinctive spatial structure is of great significance, but full of challenges, as it could not be effectively recognized via either an active covalent reaction process or multiple noncovalent interactions toward its simple structure. Here, the electronic-effect-driven recognition strategy was proposed to visually sense an illicit drug, γ-hydroxybutyric acid (GHB), which was treated as an analyte model due to its inherent simple structure. In particular, a sensing system composed of two probes substituted by the nitro (-NO2) and the hydrogen (-H), was constructed with the characteristic yellow coloring and blue fluorescence, as well as high sensitivity (0.586 ng/mL), fast response (0.2 s), and specific recognition, even in the presence of 22 interferents. In addition, a portable eyeshadow box-like sensing chip was fabricated and proven to be reliable and feasible in sensing GHB disguised in liquors for self-protection in a covert manner. Hence, this work developed an electronic-effect-driven modulation strategy of the recognition interaction between the probe and the analyte and, thus, would open up a new thought for detecting the analyte with weak activity and a simple structure, as well as propel the relevant application in real scenarios.

Highly sensitive and selective photoelectrochemical detection of bis(2-ethylhexyl)phthalate on broad-spectrum responsive and interfacial electronic interaction induced p-n BiOI/ZnO nanoarrays heterojunction

Bis(2-ethylhexyl)phthalate (DEHP), an endocrine disruptor, shows carcinogenic, teratogenic, mutagenic and estrogenic effects. It is easy to release from plastic materials and migrate to soil environment, causing serious pollution and posing a great threat to human health. In our work, a photoelectrochemical (PEC) sensing platform for DEHP detection was constructed using BiOI/ZnO nanoarrays (NRs) as the transducer species and the DEHP aptamers as the biological recognition elements. ZnO NRs with three-dimensional and large diameter area were prepared by hydrothermal method to increase the light absorption capacity. Coupling BiOI in a narrow band gap with ZnO NRs strengthened visible-light absorption, while promoting charge carrier separation and transportation. This was attributed to the generation of an internal electric field between BiOI and ZnO NRs, exhibiting obvious photocurrent response. The as-developed PEC sensing platform demonstrated great sensing performance for detection of DEHP. Furthermore, the photocurrent varied and the logarithm of DEHP concentration showed a linear relationship from 1.0 × 10-11 to 5.0 × 10-7 mol/L, and the limit of detection was estimated to be 3.8 × 10-12 mol/L. In the meantime, while evaluating its usage in real soil samples, satisfying outcomes were realized. Thus, the as-proposed PEC sensing platform provided a potential device to monitor DEHP in the environment.

Analysis and remediation of phthalates in aquatic matrices: current perspectives

Phthalic acid esters (PAEs) are high production volume chemicals used extensively as plasticizers, to increase the flexibility of the main polymer. They are reported to leach into their surroundings from plastic products and are now a ubiquitous environmental contaminant. Phthalate levels have been determined in several environmental matrices, especially in water. These levels serve as an indicator of plasticizer abuse and plastic pollution, and also serve as a route of exposure to different species including humans. Reports published on effects of different PAEs on experimental models demonstrate their carcinogenic, teratogenic, reproductive, and endocrine disruptive effects. Therefore, regular monitoring and remediation of environmental water samples is essential to ascertain their hazard quotient and daily exposure levels. This review summarises the extraction and detection techniques available for phthalate analysis in water samples such as chromatography, biosensors, immunoassays, and spectroscopy. Current remediation strategies for phthalate removal such as adsorption, advanced oxidation, and microbial degradation have also been highlighted.

Single-Chain Conjugated Polymer Guests Confined inside Metal-Organic Frameworks (MOFs): Boosting the Detection and Degradation of a Sulfur Mustard Simulant

Real-time detection and effective degradation of toxic gases have attracted considerable attention in environmental monitoring and human health. Here, we demonstrate a solvent-assisted dynamic assembly strategy to strongly enhance the detection and degradation performance for 2-chloroethyl ethyl sulfide (CEES, as a sulfur mustard simulant) via confinement of a conjugated polymer in metal-organic frameworks (MOFs). The conjugated polymer poly(9,9-di-n-octylfluorene-altbenzothiadiazole) (F8BT) is infiltrated into one-dimensional nanochannels of the Zr-based topological MOF NU-1000 in a single-chain manner, which is caused by the nanoconfinement effect and the steric hindrance between 9,9-dioctylfluorene units and benzothiadiazole units. The obtained F8BT⊂NU-1000 composites provide a high specific surface area and abundant active sites. Based on the cooperative effect of F8BT and NU-1000, rapid and sensitive detection of CEES has been achieved. Moreover, the F8BT⊂NU-1000 composites can selectively oxidize CEES into 2-chloroethyl ethyl sulfoxide (CEESO) under mild photooxidation conditions. Overall, this study opens a new avenue for the fabrication of conjugated polymer/MOF hybrid materials that show great potential for the sensitive detection and effective removal of hazardous chemicals.

A review on solution- and vapor-responsive sensors for the detection of phthalates

Phthalic acid esters, largely referred to as phthalates, are today acknowledged as important pollutants used in the manufacture of polyvinyl chloride (PVC)-based plastics, whose use extends to almost every aspect of modern life. The risk of exposure to phthalates is particularly relevant as high concentrations are regularly found in drinking water, food-contact materials and medical devices, motivating an immense body of research devoted to methods for their detection in liquid samples. Conversely, phthalate vapors have only recently been acknowledged as potentially important atmospheric pollutants and as early fire indicators; additionally, deposition of these vapors can pose significant problems to the proper functioning of spacecraft and diverse on-board devices, leading to major space agencies recognizing the need of developing vapor-responsive phthalate sensors. In this manuscript we present a literature survey on solution- and vapor-responsive sensors and analytical assays for the detection of phthalates, providing a detailed analysis of a vast array of analytical data to offer a clear idea on the analytical performance (limits of detection and quantification, linear range) and advantages provided by each class of sensor covered in this review (electrochemical, optical and vapor-responsive) in the context of their potential real-life applications; the manuscript also gives detailed fundamental information on the various physicochemical responses exploited by these sensors and assays that could potentially be harnessed by new researchers entering the field.

Illuminating the path: aggregation-induced emission for food contaminants detection

Food safety is a global concern that deeply affects human health. To ensure the profitability of the food industry and consumer safety, there is an urgent need to develop rapid, sensitive, accurate, and cost-effective detection methods for food contaminants. Recently, the Aggregation-Induced Emission (AIE) has been successfully used to detect food contaminants. AIEgens, fluorescent dyes that cause AIE, have several valuable properties including high quantum yields, photostability, and large Stokes shifts. This review provides a detailed introduction to the principles and advantages of AIE-triggered detection, followed by a focus on the past five years' applications of AIE in detecting various food contaminants including pesticides, veterinary drugs, mycotoxins, food additives, ions, pathogens, and biogenic amines. Each detection principle and component is comprehensively covered and explained. Moreover, the similarities and differences among different types of food contaminants are summarized, aiming to inspire future researchers. Finally, this review concludes with a discussion of the prospects for incorporating AIEgens more effectively into the detection of food contaminants.

A metal-organic framework regulated graphdiyne-based electrochemiluminescence sensor with a electrocatalytic self-acceleration effect for the detection of di-(2-ethylhexyl) phthalate

In this work, a super-sensitive electrochemiluminescence (ECL) aptamer sensor was constructed using a multiple signal amplification strategy to realize ultra-sensitive detection of di-(2-ethylhexyl) phthalate (DEHP). The incorporation of a highly efficient electrocatalytic metal-organic framework (NH2-Zr-MOF) and graphdiyne (GDY) composite has significantly enhanced the overall electrochemically active surface area, facilitating electron transfer during the entire electrochemical reaction process, and the large number of pores in graphdiyne and NH2-Zr-MOF limited a series of redox reactions within a certain range. This resulted in the generation of a greater number of SO4˙- radicals, thereby boosting the ECL intensity of the GDY in the K2S2O8 system. To increase the performance of the sensor even further, sodium ascorbate (NaAsc) as an accelerator was added to the co-reactant system. Additionally, nitrogen micro-nano bubbles with higher stability and stronger mass transfer have been introduced into the ECL system for the first time. Based on these, the aptamer as the recognition element realized the ultra-sensitive detection of DEHP in the linear range of 1.0 × 10-12 to 1.0 × 10-4 mg mL-1 with the limit of detection (LOD) of 2.43 × 10-13 mg mL-1. In summary, we have utilized the electrocatalytic activity of the porous MOF and the reducing capability of sodium ascorbate to enhance the ECL emission of GDY, which has been successfully applied to the detection of DEHP in water samples.

Nonconfinement growth of edge-curved molecular crystals for self-focused microlasers

Synthesis of single-crystalline micro/nanostructures with curved shapes is essential for developing extraordinary types of optoelectronic devices. Here, we use the strategy of liquid-phase nonconfinement growth to controllably synthesize edge-curved molecular microcrystals on a large scale. By varying the molecular substituents on linear organic conjugated molecules, it is found that the steric hindrance effect could minimize the intrinsic anisotropy of molecular stacking, allowing for the exposure of high-index crystal planes. The growth rate of high-index crystal planes can be further regulated by increasing the molecular supersaturation, which is conducive to the cogrowth of these crystal planes to form continuously curved-shape microcrystals. Assisted by nonrotationally symmetric geometry and optically smooth curvature, edge-curved microcrystals can support low-threshold lasing, and self-focusing directional emission. These results contribute to gaining an insightful understanding of the design and growth of functional molecular crystals and promoting the applications of organic active materials in integrated photonic devices and circuits.

Rapid Assessment of Meat Freshness by the Differential Sensing of Organic Sulfides Emitted during Spoilage

In this work, we report the fabrication of a two-member fluorescence sensor array that enables the assessment of three stages (fresh, slightly spoiled, and moderately or severely spoiled) of meat spoilage. The first member of the array, which has strong chalcogen bonding and sulfur-π interactions with organic sulfides, exhibits very high sensitivity, while the second member of the array, which has weak chalcogen bonding and sulfur-π interactions with organic sulfides, exhibits lower sensitivity. On the basis of the combined fluorescence responses of the two members, three stages of meat spoilage, including fresh, slightly spoiled, and moderately or severely spoiled, can be monitored. Notably, using the volatiles collected from 5 g of meat products over a short period of time (1 min), this two-member sensor array achieves sensitive responses to the organic sulfides emitted from the meats. The capacity of this method to rapidly assess meat freshness facilitates its practical application, as illustrated by the monitoring of the freshness of chicken and pork products in the real world.

Development of a Fluorophore with Enhanced Unorthodox Chalcogen Bonding for Highly Sensitive Detection of Trimethyl Arsine Vapor

In this work, we report the design of novel fluorophores that bear three benzothiadiazole and benzoselenadiazole groups, respectively, for sensitive detection of trimethyl arsine vapor. In particular, the fluorophore with the benzoselenadiazole groups can form stronger chalcogen bonding with trimethyl arsine than the fluorophore with the benzothiadiazole groups, which in turn triggers much faster and more sensitive fluorescence responses. On the basis of this novel mechanism, fluorescence detection of trimethyl arsine vapor with rapid response (∼3 s), high sensitivity (the theoretical LOD is 0.44 ppb), and high selectivity is achieved on bundled nanofibers from the fluorophore with the benzoselenadiazole groups. Here, the new fluorescence sensor may find wide applications in health and environmental monitoring, arsenic distribution recognition in soil, and arsenic mines exploration.

Amphiphilic BODIPY-based nanoparticles as "light-up" fluorescent probe for PAEs detection by an aggregation/disaggregation approach

Phthalic acid eaters (PAEs) play the role of plasticizer and have been widely used in the industrial and plastic production process. But due to not chemically bound in the polymeric matrix, PAEs can be easily released directly and/or indirectly into the environment, and pose a threat the ecosystem and human health. Small-molecule self-assembled nanoparticles have drawn more and more attention due to advantages of precise molecular structure, biocompatibility, great diversity, and tunability in optical properties and functionalities. Here we report the use of disaggregation-induced emission (DIE) based supramolecular assembly to design organic nanoprobe for detection PAEs. In the water solution, the designed small organic fluorophore AJ-1 was aggregated via noncovalent forces to form fluorescence off nanoparticles, but in the presence of PAEs, they disaggregated and produced a clear light-up fluorescent signal. The detection of PAEs with selectivity, sensitivity and rapid response were further achieved. The experiment of recovery of PAEs in real-water sample illustrated the practicability of probe AJ-1 in real-world applications. Besides, cellular uptake assay suggested that AJ-1 could pass through membrane and gather in the cytoplasm.

High-Performance Trichloroacetic Acid Sensor Based on the Intramolecular Hydrogen Bond Formation and Disruption of a Specially Designed Fluorescent o-Carborane Derivative in the Film State

Discriminative and sensitive detection of environmentally important and health-related trichloroacetic acid (TCA) suffers from various problems such as bulky instruments and time-consuming operation as well as complex sample processing. Herein, we present a rapid, sensitive, and specific method for the detection of gaseous TCA using a fluorescent single-molecule array. An o-carborane-based benzothiazole derivative (CB-BT-OCH₃) with specific fluorescence properties was specifically designed and utilized to fabricate a film-based single-molecule array. It was revealed that the fluorescent film is photochemically stable and extremely sensitive to TCA vapor, depicting an observable fluorescence color change from green to blue. The experimental detection limit is 0.2 ppm, which is lower than the safety limit (1 ppm) required by the threshold limit values and biological exposure indices. In addition, the film could show detectable intensity change within 0.2 s. On the basis of multiple signal responses, a conceptual two-channel-based fluorescent TCA sensor was developed. Importantly, the proposed conceptual sensor paves a new route to the development of specific fluorescent film-based sensor arrays with a single fluorophore as sensing units.

Highly Photostable and Luminescent Donor-Acceptor Molecules for Ultrasensitive Detection of Sulfur Mustard

Real-time, high signal intensity, and prolonged detection is challenging because of the rarity of fluorophores with both high photostability and luminescence efficiency. In this work, new donor-acceptor (D-A) molecules for overcoming these limitations are reported. A hybridized local and an intramolecular charge-transfer excited state is demonstrated to afford high photoluminescence efficiency of these D-A molecules in solution (≈100%). The twisted molecular structure and bulky alkyl chains effectively suppress π-π and dipole-dipole interactions, enabling high luminescence efficiency of 1 and 2 in the solid state (≈94% and 100%). Furthermore, two D-A aggregates exhibit high photostability as evidenced by 4% and 8% of the fluorescence decreasing after 6 h of continuous irradiation in air, which is in sharp contrast to ≈95% of fluorescence decreasing in a reference compound. Importantly, with these molecules, ultrasensitive detection of sulfur mustard (SM) with a record limit of 10 ppb and selective detection of SM in complex matrices are achieved.

Electrokinetic Preseparation and Molecularly Imprinted Trapping for Highly Selective SERS Detection of Charged Phthalate Plasticizers

Nonspecific binding and weak spectral discernment are the main challenges for surface-enhanced Raman scattering (SERS) detection, especially in real sample analysis. Herein, molecularly imprinted polymer (MIP)-based core-shell AuNP@polydopamine (AuNP@PDA-MIP) nanoparticles (NPs) are designed and immobilized on an electrochemically reduced MoS₂-modified screen-printed electrode (SPE). This portable electrochemical-Raman interface offers the dual functions of electrokinetic preseparation (EP) and MIP trapping of charged molecules so that a reliable SERS recognition with molecular selectivity and high sensitivity can be achieved. Core-shell AuNP@PDA-MIP NPs can be controllably synthesized, possess predesigned specific recognition, and provide "hot spots" at the junction of NPs. The introduction of an electric field enables the autonomous exclusion and separation of similarly charged molecules as well as attraction and concentration of the oppositely charged molecules by electrostatic attraction. Subsequently, the specific MIP recognition cavities allow selective adsorption of targets on the interface without the interference of analogues. Owing to the distinctive design of the multiple coupling separation, trapping, and enrichment strategies, the MIP-based SERS-active interface can be used for label-free detection of charged molecules in real samples without pretreatment. As a proof-of-concept study, label-free SERS detection of charged phthalate plasticizers (PAEs) was demonstrated with a detection limit as low as 2.7 × 10^-12 M for dimethyl phthalate (DMP) and 2.3 × 10^-11 M for di(2-ethylhexyl) phthalate (DEHP). This sensing strategy for in situ SERS analysis of charged pollutants or toxins holds vast promises for a wide range of in-field applications.

Luminol-Based Turn-On Fluorescent Sensor for Selective and Sensitive Detection of Sulfur Mustard at Ambient Temperature

We have explored a novel turn-on fluorescence detection of sulfur mustard (SM) at "room temperature". The innovative protocol that uses the combination of luminol and an ionic liquid in water exhibits fluorescence detection of SM within seconds. In this simple, fast, and low-cost chemosensing method, luminol acts as the receptor as well as a signaling element, and the ionic liquid (1-ethyl-3-methylimidazolium dicyanamide) provides the requisite and polarizing medium to realize the detection at "room temperature". Interestingly, with a higher concentration of a probe (0.56 mM), SM sensing can be visualized with the naked eye, leading to the formation of a fluorescent green color within a minute, thus expanding the application of the developed sensing technique for chromo-fluorogenic detection of SM. Excellent selectivity, sensitivity (LOD: 6 ppm), and chemosensing at ambient temperature make this methodology completely field-deployable.