Visual recognition of melamine in milk via selective metallo-hydrogel formation

Energy & Environ Materials

Sarkar

Xie

et al. 2023

The ever‐increasing complexity of environmental pollutants urgently warrants the development of new detection technologies. Sensors based on the optical properties of hydrogels enabling fast and easy in situ detection are attracting increasing attention. In this paper, the data from 138 papers about different optical hydrogels (OHs) are extracted for statistical analysis. The detection performance and potential of various types of OHs in different environmental pollutant detection scenarios were evaluated and compared to those obtained using the standard detection method. Based on this analysis, the target recognition and sensing mechanisms of two main types of OHs are reviewed and discussed: photonic crystal hydrogels (PCHs) and fluorescent hydrogels (FHs). For PCHs, the environmental stimulus response, target receptors, inverse opal structures, and molecular imprinting techniques related to PCHs are reviewed and summarized. Furthermore, the different types of fluorophores (i.e., compound probes, biomacromolecules, quantum dots, and luminescent microbes) of FHs are discussed. Finally, the potential academic research directions to address the challenges of applying and developing OHs in environmental sensing are proposed, including the fusion of various OHs, introduction of the latest technologies in various fields to the construction of OHs, and development of multifunctional sensor arrays.

Section: Concept and Performance Analysis Of Different Optical Sensorsmentioning

confidence: 99%

Application of Optical Hydrogels in Environmental Sensing

Energy & Environ Materials

Sarkar

Xie

et al. 2023

“…As reported in the selected papers, OHs can detect heavy metals, anions, antibiotics, pesticides, small organics, gas molecules, environmental parameters, and microorganisms in the environment (Figure 16a) . Additionally, OHs can detect much more targets such as anesthetics in fish [220] , metabolites of microorganisms in complex media [221] , melamine in milk [222] , and catecholamines in serum [223] . These examples indicate that OHs have broad potential for detecting increasingly complex contaminants in the environment, and this field needs more research.…”

Section: Detection Performance Analysismentioning

confidence: 99%

Application of optical hydrogels in environmental sensing

Sarkar

Xie

et al. 2023

Preprint

The ever-increasing complexity of environmental pollutants urgently warrants the development of new detection technologies. In this context, sensors based on the optical properties of hydrogels enabling fast and easy in situ detection are attracting increasing attention. Herein, the target recognition and sensing mechanisms of two main types of optical hydrogels (OHs) are reviewed and discussed: photonic crystal hydrogels (PCHs) and fluorescent hydrogels (FHs). For PCHs, the environmental stimulus response, target receptors, inverse opal structures, and molecular imprinting techniques related to PCHs are reviewed and summarized. Furthermore, the different types of fluorophores (i.e., compound probes, biomacromolecules, quantum dots, and luminescent microbes) of FHs are summarized. Finally, the data from 138 papers about different OHs are extracted for secondary statistical analysis. The detection performance and potential of various OH types in different environmental pollutant detection scenarios are evaluated, and compared them to those obtained using the standard detection method. Based on this analysis, some possible development directions are proposed, including the fusion of various OHs, introduction of more hydrogel technologies from the biomedical field to the environmental pollutant detection field, and development of multifunctional sensor arrays.

“…High stability is important in enhancing the performance of gel catalyst recycling. Stable polymer gels with acid- and alkali-resistant properties as adsorbents have aroused the interest of scientists. ,− On the other hand, supramolecular gels assembled from small molecules via hydrogen bonding, π–π stacking, van der Waals interactions, and other supramolecular weak interactions have been developed as adsorbents and catalysts in recent years. − Supramolecular gels show greater structural diversity and easier incorporation of functional groups than polymer gels. They have potential for the adsorption of pollutants because small molecules or metal ions can rapidly diffuse within them easily.…”

Section: Introductionmentioning

confidence: 99%

Synthesis of a Stable Benzoxazole Gel from an Imine Gel for Adsorption and Catalysis

Chen

et al. 2021

Langmuir

Developing stable gel materials for adsorption and catalysis is one of the major themes of gel materials. However, it has been proven to be challenging to achieve them from small molecules. Herein, an imine gel is developed from tetra-aldehyde 4-{2,2-bis[(4-formylphenoxy)methyl]-3-(4-formylphenoxy)propoxy}benzaldehyde (A4) and 3,3′-dihydroxybenzidine (B2) based on dynamic covalent chemistry. The unstable A4B2-imine gel is further converted into a stable aromatic benzoxazole-linked A4B2-benzoxazole gel via oxidative cyclization, which has significantly improved chemical stability under acidic and basic conditions. Benefiting from the stability under acidic conditions, the A4B2-benzoxazole gel is used for Pd(II) adsorption and the adsorption capacity is 250 mg g–1. After PdCl2 immersion and reduction, palladium nanoparticles with a size distribution of 1.3–14.7 nm are encapsulated by the network structure of the stable porous benzoxazole gel matrix. The Pd@A4B2-benzoxazole gel exhibits high catalytic activity toward the reduction of toxic hexavalent chromium Cr(VI) (reaction rate constant = 0.0377 min–1), while there is no significant decrease in the catalytic efficiency after five cycles.