Luminescent cellulose-based porous binary metal-organic gels in an adsorption bed for effective adsorption and sensitive detection of chlortetracycline hydrochloride

MOFs-based aerogels and their derivatives for water treatment: A review

Metal-organic frameworks (MOFs) are a class of environmental nano-materials composed of metal ions and organic ligands with remarkable physical and chemical properties, such as huge specific surface area as well as abundant pore volume. Based on their unique structures and properties, MOFs have demonstrated potential applications in the fields of adsorption, gas storage, separation membranes, and catalysis, and have become popular candidates in water treatment technologies. However, MOFs particles in powder form are prone to agglomeration and adhesion effects in water, which leads to problems such as difficult separation and secondary pollution. As an ideal carrier for MOFs, aerogels exhibit a unique three-dimensional interconnected pore structure, which endows aerogels with high porosity properties and excellent adsorption capacity. Researchers have skillfully combined MOFs with aerogels to create a new type of MOF aerogel composites (MOFACs). These composites are converted into highly porous and high-strength carbon aerogels through a high-temperature pyrolysis process in an inert environment. These carbon aerogels not only retain the high catalytic efficiency of MOFs, but also inherit the advantages of aerogels in terms of light weight, low density and easy handling. This paper reviews various types of MOFACs, each of which possesses different chemical compositions and physical properties, thus adapting to different applications. The paper also discusses the applications of MOFACs and carbon aerogels in water treatment for catalysis, selective adsorption and solid phase microextraction.

Monitoring and Analysis of Total Tetracyclines in Water from Different Environmental Scenarios Using a Designed Broad-Spectrum Aptamer

Tetracyclines (TCs) are widely present in the environment with extreme toxicity, low concentrations, coexistence with a variety of pollutants, and similarity in their individual molecular structures and toxicology. These challenges make it difficult to analyze and monitor TCs as a class of molecules simultaneously. In this study, a broad-spectrum aptamer capable of recognizing TCs was developed by artificially editing a single-specific aptamer. Subsequently, based on the mathematical proof of broad-spectrum aptamer detection of TCs, an electrochemical sensor was constructed to enable simple and rapid monitoring of TCs with high sensitivity, high selectivity, and a wide detection range. The sensor exhibits a detection range of 0.01 to 1000 nM and a detection limit of 1.18 pM, while maintaining excellent selectivity even in the presence of interfering substances at concentrations up to 100 times the test concentration. This sensor is suitable for quantifying the overall level of TCs in various environmental scenarios, facilitating the study of TCs transport and transformation processes in environmental systems. Finally, the broad-spectrum recognition mechanism of the aptamer was elucidated, which makes the method rational and universal, and will help future researchers to obtain broad-spectrum aptamers for rapid monitoring and analysis of multiple classes of pollutants.

Recent Progress in MOF-Aerogel Fabrication and Applications

Recent advancements in metal-organic frameworks (MOFs) underscore their significant potential in chemical and materials research, owing to their remarkable properties and diverse structures. Despite challenges like intrinsic brittleness, powdered crystalline nature, and limited stability impeding direct applications, MOF-based aerogels have shown superior performance in various areas, particularly in water treatment and contaminant removal. This review highlights the latest progress in MOF-based aerogels, with a focus on hybrid systems incorporating materials like graphene, carbon nanotube, silica, and cellulose in MOF aerogels, which enhance their functional properties. The manifold advantages of MOF-based aerogels in energy storage, adsorption, and catalysis are discussed, with an emphasizing on their improved stability, processability, and ease of handling. This review aims to unlock the potential of MOF-based aerogels and their real-world applications. Aerogels are expected to reshape the technological landscape of MOFs through enhanced stability, adaptability, and efficiency.

Recent Advances in Hierarchical Porous Engineering of MOFs and Their Derived Materials for Catalytic and Battery: Methods and Application

Hierarchical porous materials have attracted the attention of researchers due to their enormous specific surface area, maximized active site utilization efficiency, and unique structure and properties. In this context, metal-organic frameworks (MOFs) offer a unique mix of properties that make them particularly appealing as tunable porous substrates containing highly active sites. This review focuses on recent advances in the types and synthetic strategies of hierarchical porous MOFs and their derived materials. Furthermore, it highlights the relationship between the mass diffusion and transport of hierarchical porous structures and the pore size with examples and simulations, while identifying their potential and limitations. On this basis, how the synthesis conditions affect the structure and electrochemical properties of MOFs based hierarchical porous materials with different structures is discussed, highlighting the prospects and challenges for the synthetization, as well as further scientific research and practical applications. Finally, some insights into current research and future design ideas for advanced MOFs based hierarchical porous materials are presented.

Synthesis of molecularly imprinted polymers based on nitrogen-doped carbon dots for specific detection of chlortetracycline by reversed phase microemulsion method

Among the tetracycline antibiotics, chlortetracycline (CTC) is the most frequently used antibiotic except for tetracycline (TC) for enhancing the ability of the organism to fight bacterial infections. The poor metabolism and degradability of CTC can cause serious health effects. Most studies have focused on the detection and analysis of TC, and research on CTC is relatively scarce. This is because the structures of CTC and TC and oxytetracycline (OTC) are extremely similar, and even indistinguishable. In this study, CTC was used as a template molecule and a molecularly imprinted layer was coated on the surface of highly fluorescent N-CDs using a reversed-phase microemulsion method to form N-CDs@MIPs. It was possible to specifically identify CTC without the influence of TC and OTC, which are extremely similar in structure. By comparing with the non-imprinted polymer (N-CDs@NIPs), it exhibited high sensitivity and selectivity with an imprinting factor of 2.02. And it was used in the determination of CTC in milk with recoveries and relative standard deviations of 96.7%-109.8% and 0.64%-3.27%, respectively, with high accuracy and precision. The specificity of the measurement is excellent compared with other assays, and it is a valid and reliable assay.

Metal-organic gels: recent advances in their classification, characterization, and application in the pharmaceutical field

Metal-organic gels (MOGs) are a type of functional soft substance with a three-dimensional (3D) network structure and solid-like rheological behavior, which are constructed by metal ions and bridging ligands formed under the driving force of coordination interactions or other non-covalent interactions. As the homologous substances of metal-organic frameworks (MOFs) and gels, they exhibit the potential advantages of high porosity, flexible structure, and adjustable mechanical properties, causing them to attract extensive research interest in the pharmaceutical field. For instance, MOGs are often used as excellent vehicles for intelligent drug delivery and programmable drug release to improve the clinical curative effect with reduced side effects. Also, MOGs are often applied as advanced biomedical materials for the repair and treatment of pathological tissue and sensitive detection of drugs or other molecules. However, despite the vigorous research on MOGs in recent years, there is no systematic summary of their applications in the pharmaceutical field to date. The present review systematically summarize the recent research progress on MOGs in the pharmaceutical field, including drug delivery systems, drug detection, pharmaceutical materials, and disease therapies. In addition, the formation principles and classification of MOGs are complemented and refined, and the techniques for the characterization of the structures/properties of MOGs are overviewed in this review.

Visual fluorescence detection of ciprofloxacin by Zn-metal-organic framework@nanocellulose transparent films based on aggregation-induced emission

The invention and production of Ciprofloxacin (CIP) have a positive impact on medical treatment, but the overuse of CIP is also harmful to the environment. In this paper, we prepared a novel film material for detection of CIP by in situ synthesis of zinc-based metal-organic framework (Zn-BDC) on TEMPO-oxidized cellulose nanofibers (TOCNF). The nanoscale Zn-BDC were uniformly distributed on the TOCNF that was beneficial to realize the transparency and functionality of Zn-BDC@TOCNF whose transparency was up to 87 %. Zn-BDC@TOCNF showed no fluorescence itself while showed bright fluorescence upon the contact of CIP, which was proposed as the aggregation-induced emission (AIE) of CIP that defused and assembled in the Zn-BDC@TOCNF. There was a certain linear relationship between fluorescence intensity and concentration of CIP (R2 = 0.994, LOD = 0.083 μM). In the detection process, CIP could still fluoresce in Zn-BDC@TOCNF even if it was interfered by other ions and small biological molecules, and the weak acid environment was conducive to AIE of CIP. Generally, it was of great significance to establish a rapid and effective monitoring mechanism for CIP in water for environmental protection and ecological balance.

Cellulose-based adsorbents for solid phase extraction and recovery of pharmaceutical residues from water

Cellulose has attracted interest from researchers both in academic and industrial sectors due to its unique structural and physicochemical properties. The ease of surface modification of cellulose by the integration of nanomaterials, magnetic components, metal organic frameworks and polymers has made them a promising adsorbent for solid phase extraction of emerging contaminants, including pharmaceutical residues. This review summarizes, compares, and contrasts different types of cellulose-based adsorbents along with their applications in adsorption, extraction and pre-concentration of pharmaceutical residues in water for subsequent analysis. In addition, a comparison in efficiency of cellulose-based adsorbents and other types of adsorbents that have been used for the extraction of pharmaceuticals in water is presented. From our observation, cellulose-based materials have principally been investigated for the adsorption of pharmaceuticals in water. However, this review aims to shift the focus of researchers to the application of these adsorbents in the effective pre-concentration of pharmaceutical pollutants from water at trace concentrations, for quantification. At the end of the review, the challenges and future perspectives regarding cellulose-based adsorbents are discussed, thus providing an in-depth overview of the current state of the art in cellulose hybrid adsorbents for extraction of pharmaceuticals from water. This is expected to inspire the development of solid phase exraction materials that are efficient, relatively cheap, and prepared in a sustainable way.

Preparation of graphene oxide-doped silica aerogel using supercritical method for efficient removal of emerging pollutants from wastewater

Emerging pollutants and a large volume of unused dyes from the textile industry have been contaminating water bodies. This work introduces a scalable approach to purifying water by the adsorption of Acid green 25 (AG), Crystal Violet (CV), and Sulfamethoxazole (SMA) from an aqueous solution by graphene oxide (GO) doped modified silica aerogel (GO-SA) with supercritical fluid deposition (SFD) method. Characterization of GO-SA using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), high-resolution scanning electron microscopy (HR-SEM), thermogravimetric analysis (TGA), and Brunauer-Emmett-Teller (BET) adsorption isotherms revealed the improvement in the adsorbent surface area, and its textural properties. The high removal percentages observed in most of the experimental runs provide evidence of the excellent performance of the adsorbent towards the anionic and cationic dyes along with the antibiotic. The adsorption isotherm and kinetics showed that the Langmuir isotherm and pseudo-second-order kinetic models could explain adsorption. The adsorbent holds a higher adsorption capacity for SMA (67.07 mg g-1) than for CV (41.46 mg g-1) and AG (20.56 mg g-1) due to the higher hydrophobicity that interacts with the hydrophobic adsorbent. The GO-SA successfully removed AG, CV, and SMA with removal percentages of 98.23%, 98.71%, and 94.46%, respectively. The parameters were optimized using Central Composite Design (RSM-CCD). The prepared aerogel showed excellent reusability with a removal efficiency of > 85% even after 5 cycles. This study shows the potential of GO-SA adsorbent in textile and other wastewater purification.

Bifunctional collagen fiber/carbon quantum dot fluorescent adsorbent for efficient adsorption and detection of Pb2

In this work, fluorescent adsorbents that can efficiently detect and remove Pb²⁺ were developed by integrating the designed amino-modified carbon quantum dots and carboxyl-modified collagen. The adsorption properties of the fluorescent adsorbent were further optimized and analyzed using a series of response surface experiments. The maximum adsorption concentration for Pb²⁺ was 183 mg.g^-1. The adsorption isotherms fit well with the Langmuir model, and the adsorption kinetics fit with the pseudo-second-order model. The emission intensity of the fluorescent adsorbent gradually decreased with the increase of the concentration of Pb²⁺, and had a good linear correlation. In addition, the mechanism of detection and removal of Pb²⁺ by fluorescent adsorbents was further demonstrated. The novel three-dimensional structured fluorescent aerogel can be used as a promising adsorbent with good adsorption concentration and sensing ability for Pb²⁺, which shows great prospects in wastewater.

Progress in Research and Application of Metal-Organic Gels: A Review

In recent years, metal-organic gels (MOGs) have attracted much attention due to their hierarchical porous structure, large specific surface area, and good surface modifiability. Compared with MOFs, the synthesis conditions of MOGs are gentler and more stable. At present, MOGs are widely used in the fields of catalysis, adsorption, energy storage, electrochromic devices, sensing, analysis, and detection. In this paper, literature metrology and knowledge graph visualization analysis are adopted to analyze and summarize the literature data in the field of MOGs. The visualization maps of the temporal distribution, spatial distribution, authors and institutions' distribution, influence of highly cited literature and journals, keyword clustering, and research trends are helpful to clearly grasp the content and development trend of MOG materials research, point out the future research direction for scholars, and promote the practical application of MOGs. At the same time, the paper reviews the research and application progress of MOGs in recent years by combining keyword clustering, time lines, and emergence maps, and looks forward to their challenges, future development trend, and application prospects.

A highly selective fluorescent sensor for chlortetracycline based on histidine-templated copper nanoclusters

In this study, histidine-protected copper nanoclusters (Cu NCs@His) were established by using a one-pot method, which histidine and ascorbic acid were applied as the template and reducing agent, respectively. The as-developed Cu NCs@His endued green emission wavelength at 494 nm with the excitation of 378 nm. The Cu NCs@His exhibited green fluorescence under UV light (365 nm). Using Cu NCs@His as a pattern nanosensor, the fluorescent "turn off" mechanism was fabricated for the determination of chlortetracycline in the light of the linear decrease of fluorescence intensities around 494 nm. The chlortetracycline conducted as a quencher, leading to reveal an excellent linear relationship between ln(F₀/F) of Cu NCs@His and chlortetracycline concentrations with the range of 0.5-200 μM, and the detection limit was 0.876 μM. The fluorescence quenching of Cu NCs@His revealed excellent selectivity for chlortetracycline over other potential interfering substances in the human body. This strategy was exhibited to be a convenient sensing platform for the detection of chlortetracycline in real medical samples, which could unfold a brand new and direct system for the sensing of chlortetracycline in real samples.

Construction of ratiometric fluorescence sensor and test strip with smartphone based on dual-emission carbon dots for the specific detection of chlortetracycline

Concerns about environmental and food contamination caused by chlortetracycline (CTC) residues have prompted people to explore efficient and convenient CTC monitoring platforms. However, the reported fluorescent probes generally fail to selectively detect CTC due to the structural similarity of tetracycline antibiotics. Herein, an intrinsic dual-emission carbon dots (D-CDs) ratiometric fluorescence sensor was prepared for highly sensitive and selective determination of CTC over other tetracyclines by one-step synthesis. The sensor exhibited a significant fluorescence enhancement at 425 nm after introducing CTC. The fluorescence "turn on" of the sensing system is due to aggregation-induced emission (AIE) phenomenon formed by hydrogen bonds and π conjugation promoting the specific recognition of CTC by D-CDs. The linear detection varied from 0.98 to 143.67 ng mL^-1 with a low limit of detection (LOD) of 1.29 ng mL^-1 (R² = 0.998), which was lower than most reported in the literature. The D-CDs sensor was applied to detect CTC in spiked milk, blocked normal human serum, and fish samples with recoveries of 95.5-104.2% and relative standard deviations (RSDs) of 2.6%. Particularly, D-CDs based test papers with a smartphone were prepared for portable and visual detection of CTC by analyzing the various color changes of RGB of fluorescence color, with an LOD of 7.18 ng mL^-1 (R² = 0.9909). The fluorescence sensor designed in this work could be used as a rapid tool with high performance and selectivity for monitoring control in foods.

Stable Metal-Organic Frameworks for Fluorescent Detection of Tetracycline Antibiotics

The rapid detection of antibiotics in agricultural products is of great significance. In this work, two stable fluorescent metal-organic frameworks (MOFs), BUT-178 and BUT-179, are synthesized and used to detect tetracycline antibiotics. Among them, BUT-179 exhibits better performance in the detection of different tetracycline antibiotics in water and eggs. The limits of detection of BUT-179 toward tetracycline, aureomycin, oxytetracycline, and doxycycline all reach the nanomolar level. Furthermore, the cycling tests confirm that BUT-179 can be easily recovered and repeatedly used without an obvious performance loss. This work demonstrates the excellent application potential of MOFs for food safety, especially the fluorescence detection of antibiotics in foods.

A gel fluorescence sensor based on CDs@SiO2/FeS2@MIPs for the visual detection of p-chlorophenol

There is a critical need for the rapid detection of p-chlorophenol produced by pesticide abuse and industrial wastewater discharge, which has been an urgent problem in the realm of environmental protection. Here, a green and environmentally friendly method was developed to prepare stable and low toxicity quantum dots. First, blue-green fluorescent FeS₂ quantum dots (B-FeS₂ QDs) were prepared with FeCl₃·6H₂O (an iron source) and L-cysteine (a capping agent) by the solvothermal method. By combining B-FeS₂ QDs with orange carbon dots (O-CDs), a CDs@SiO₂/FeS₂@MIPs visual fluorescence sensor for the selective detection of p-chlorophenol was constructed. Under optimum conditions, this sensor exhibited a detection limit of 1.265 μM with a linear range of 5.00-50.00 μM and was successfully applied to detect p-chlorophenol in real samples. Moreover, this sensor was successfully applied to visual semi-quantitative detection of p-chlorophenol. This work demonstrated that these sensors, based on FeS₂ QDs and CDs, had potentials for in situ and visual detection of environmental contaminants.

Hierarchical porous metal–organic gels and derived materials: from fundamentals to potential applications

This review summarizes recent progress in the development and applications of metal–organic gels (MOGs) and their hybrids and derivatives dividing them into subclasses and discussing their synthesis, design and structure–property relationship.

Luminescent porous metal–organic gels for efficient adsorption and sensitive detection of chlortetracycline hydrochloride assisted by smartphones and test paper-based analytical device

Developing dual functional materials for chlortetracycline hydrochloride (CTC) adsorption and detection is of great importance for wastewater treatment and pollution monitoring. Herein, three novel (Fe-Tb) JLUE-MOGs are synthesized through the...

Mesoporous polystyrene-based microspheres with polar functional surface groups synthesized from double emulsion for selective isolation of acetoside

In this study, a series of the functionalized mesoporous polystyrene-based microspheres (FMPMs) with different functional comonomers (acrylamide, AM; ethyleneglycol dimethacrylate, EGDMA; hydroxyethyl methacrylate, HEMA) and ratios of styrene (St) to divinylbenzene (DVB) were designed and synthesized by a double emulsion interface polymerization method. Among them, St and DVB existed in the oil phase, forming the skeleton structure of FMPMs. AM, EGDMA or HEMA in the water phase formed functional layers on the inner and outer surfaces of FMPMs. The experimental results indicated that the optimal functional comonomers and the ratio of St to DVB were AM (provided the hydrophilic -CONH₂ groups) and 1:1, respectively. Thus, A-FMPMs-2 exhibited the highest adsorption capacity of 108.95 ± 8.13 mg/g and the selectivity of 5.14 ± 0.17. These results were attributed to the hydrophilic -CONH₂ groups on A-FMPMs-2, and these groups were beneficial to ACT molecules diffusion driven by concentration gradient, improving the adsorption performance. Furthermore, hydrophilic -CONH₂ groups on the inner and outer surfaces of A-FMPMs-2 acted as hydrophilic sites that had a high-affinity interaction with ACT molecules, thus increasing the adsorption selectivity. In addition, A-FMPMs-2 had the highest specific surface area and largest pore volume, resulting in the highest adsorption capacity and adsorption selectivity. Therefore, the development of adsorbents with adjustable pore structure and a large number of hydrophilic sites will provide a new strategy for selective separation of bioactive components from natural products.