Fabrication and application of a novel electrochemical biosensor based on a mesoporous carbon sphere@UiO-66-NH2/Lac complex enzyme for tetracycline detection

Boosting ultrasensitive electroanalytical detection of antibiotics at triphasic interface enzymatic biosensor

Electroanalytical procedures are often closely bound up the gas molecules. However, the detection limitation of some electroanalytical procedures was largely limited by the lower solubility of gas molecules in liquid. To address this problem, a photoelectrochemical enzymatic biosensor with triphasic interface was designed for antibiotics detection. The hydrophobic porous carbon paper (CP) with atomic layer deposition (ALD) Zinc oxide (ZnO) film and Tungsten disulfide (WS2) sheets were used for fixing laccase (Lac) to form Lac/WS2/ZnO/CP, which contacted with analyst solution on one side and exposed to the gas phase directly on the other. Impressively, the catalytic activity of Lac on WS2/ZnO/CP was promoted by adjusting the oxygen concentration from the gas phase and generated significant electrochemical response for sensitively detecting tetracycline (TC), resulting in minimum detection limit of 1.81 fM in the range of 10-200 μM. Additionally, the recovery rate of environmental samples remained at 96.07 %-104.48 %, confirming the reliability and practicality of the prepared biosensors. This strategy provided a potential method to upgrade the optical properties and enzyme activities of biosensor with eventual applications in bioanalysis.

A novel biosensor MDC@N-MMCNs to selective detection and elimination of foodborne bacterial pathogens

BACKGROUND

Infections caused by foodborne pathogens pose a major threat to human health. Traditional bacterial detection methods, such as plate culture and polymerase chain reaction, cannot meet the growing demand for fast and accurate detection. In contrast, colorimetric sensors have the characteristics of convenience, speed, and visualization, but their specific sensitivity is relatively poor. Therefore, it is necessary to develop a biosensor with selective identification of foodborne pathogens, high sensitivity, and early detection of foodborne pathogen contamination in food.

RESULTS

We have developed a broad-spectrum microbial detection biosensor platform MDC@N-MMCNs that combines antimicrobial peptides as identifying ingredients with mesoporous carbon with peroxidase-like activity to detect and eliminate foodborne pathogens rapidly. In this study, nitrogen-doped magnetic mesoporous carbon nanospheres (N-MMCNs) were prepared using ferric nitrate as the magnetic source. Musca domestica cecropin (MDC) has abundant recognition sites on the surface of bacteria, which helps to recognize and amplify the signal, and combines with N-MMCNs to form MDC@N-MMCNs. MDC@N-MMCNs have high stability, specificity, and sensitivity, with a visual detection limit as low as 102 CFU/mL. The MDC@N-MMCNs paper-based sensor enables selective and rapid detection of four foodborne pathogens via a smartphone application.

SIGNIFICANCE

Based on these findings, we believe that MDC@N-MMCNs hold great potential for on-site bacterial infection diagnosis in resource-limited environments or point-of-care (POCT) settings, offering a simple, cost-effective solution for food safety and public health.

Host molecules inside metal-organic frameworks: host@MOF and guest@host@MOF (Matrjoschka) materials

The controllable encapsulation of host molecules (such as porphyrin, phthalocyanine, crown ether, calixarene or cucurbituril organic macrocycles, cages, metal-organic polyhedrons and enzymes) into the pores of metal-organic frameworks (MOFs) to form host-in-host (host@MOF) materials has attracted increasing research interest in various fields. These host@MOF materials combine the merits of MOFs as a host matrix and functional host molecules to exhibit synergistic functionalities for the formation of guest@host@MOF materials in sorption and separation, ion capture, catalysis, proton/ion conduction and biosensors. (This guest@host@MOF construction is reminiscent of Russian (Matrjoschka) dolls which are nested dolls of decreasing size placed one inside another.) In this tutorial review, the advantages of MOFs as a host matrix are presented; the encapsulation approaches and general important considerations for the preparation of host@MOF materials are introduced. The state-of-the-art examples of these materials based on different host molecules are shown, and representative applications and general characterization of these materials are discussed. This review will guide researchers attempting to design functional host@MOF and guest@host@MOF materials for various applications.

Monitoring Antibiotic Pollutants in Water Using Electrochemical Techniques: A Detailed Review

This review article examines the application of electrochemical methods for detecting four prevalent antibiotics - azithromycin (AZM), amoxicillin (AMX), tetracycline (TC), and ciprofloxacin (CIP) - in environmental monitoring. Although, antibiotics are essential to contemporary treatment, their widespread usage has contaminated the environment and given rise to antibiotic resistance. Electrochemical techniques offer sensitive, rapid, and cost-effective solutions for monitoring these antibiotics, addressing the limitations of traditional methods. The review provides a comprehensive analysis of various electrochemical approaches, including voltammetry, amperometry, photoelectrochemical and so on, highlighting their principles, advantages, and limitations. Key findings underscore the effectiveness of these methods in detecting antibiotics at trace levels in complex environmental matrices. Implications for environmental health and policy are discussed, emphasizing the importance of reliable detection techniques in mitigating antibiotic resistance and safeguarding ecosystems. Lastly, the article outlines future research directions aimed at enhancing the sensitivity, selectivity, and field-applicability of electrochemical sensors, thus advancing their utility in environmental monitoring and public health protection.

Bioremediation of organic pollutants by laccase-metal-organic framework composites: A review of current knowledge and future perspective

Immobilized laccases are widely used as green biocatalysts for bioremediation of phenolic pollutants and wastewater treatment. Metal-organic frameworks (MOFs) show potential application for immobilization of laccase. Their unique adsorption properties provide a synergic effect of adsorption and biodegradation. This review focuses on bioremediation of wastewater pollutants using laccase-MOF composites, and summarizes the current knowledge and future perspective of their biodegradation and the enhancement strategies of enzyme immobilization. Mechanistic strategies of preparation of laccase-MOF composites were mainly investigated via physical adsorption, chemical binding, and de novo/co-precipitation approaches. The influence of architecture of MOFs on the efficiency of immobilization and bioremediation were discussed. Moreover, as sustainable technology, the integration of laccases and MOFs into wastewater treatment processes represents a promising approach to address the challenges posed by industrial pollution. The MOF-laccase composites can be promising and reliable alternative to conventional techniques for the treatment of wastewaters containing pharmaceuticals, dyes, and phenolic compounds. The detailed exploration of various immobilization techniques and the influence of MOF architecture on performance provides valuable insights for optimizing these composites, paving the way for future advancements in environmental biotechnology. The findings of this research have the potential to influence industrial wastewater treatment and promoting cleaner treatment processes and contributing to sustainability efforts.

Zinc-doped carbon quantum dots-based ratiometric fluorescence probe for rapid, specific, and visual determination of tetracycline hydrochloride

In this work, a rapid, specific, and visual ratiometric fluorescence probe was constructed for tetracycline hydrochloride (TCH) determination based on zinc-doped carbon quantum dots (Zn-CDs). In the presence of TCH, the blue fluorescence at 440 nm originating from Zn-CDs was quenched, and the green fluorescence at 515 nm stemming from TCH was enhanced. The inner filter effect (IFE) and the chelation between Zn and tetracycline are the main mechanisms for the conversion of spectra. The spectrum and color change completed and stabilized within 1 min, indicating the possibility of real-time detection of TCH. The detection range for TCH is 0.1-50 μM, and the low detection limit is 61.1 nM. In addition, Zn-CDs-based test strips were successfully applied to direct visual identification of TCH in actual samples of river water and milk, indicating the possibility of their practical application.

Enzyme-Linked Metal Organic Frameworks for Biocatalytic Degradation of Antibiotics

Metal organic frameworks (MOFs) are multi-dimensional network of crystalline material held together by bonding of metal atoms and organic ligands. Owing to unique structural, chemical, and physical properties, MOFs has been used for enzyme immobilization to be employed in different catalytic process, including catalytic degradation of antibiotics. Immobilization process other than providing large surface provides enzyme with enhanced stability, catalytic activity, reusability, and selectivity. There are various approaches of enzyme immobilization over MOFs including physical adsorption, chemical bonding, diffusion and in situ encapsulation. In situ encapsulation is one the best approach that provides extra stability from unfolding and denaturation in harsh industrial conditions. Presence of antibiotic in environment is highly damaging for human in particular and ecosystem in general. Different methods such as ozonation, oxidation, chlorination and catalysis are available for degradation or removal of antibiotics from environment, however these are associated with several issues. Contrary to these, enzyme immobilized MOFs are novel system to be used in catalytic degradation of antibiotics. Enzyme@MOFs are more stable, reusable and more efficient owing to additional support of MOFs to natural enzymes in well-established process of photocatalysis for degradation of antibiotics aimed at environmental remediation. Prime focus of this review is to present catalytic degradation of antibiotics by enzyme@MOFs while outlining their synthetics approaches, characterization, and mechanism of degradation. Furthermore, this review highlights the significance of enzyme@MOFs system for antibiotics degradation in particular and environmental remediation in general. Current challenges and future perspective of research in this field are also outlined along with concluding comments.

Graphical Abstract

Electrochemical Biosensor Based on Chitosan- and Thioctic-Acid-Modified Nanoporous Gold Co-Immobilization Enzyme for Glycerol Determination

An electrochemical biosensor based on chitosan- and thioctic-acid-modified nanoporous gold (NPG) co-immobilization glycerol kinase (GK) and glycerol-3-phosphate oxidase (GPO) was constructed for glycerol determination in wine. The NPG, with the properties of porous microstructure, large specific surface area, and high conductivity, was beneficial for protecting the enzyme from inactivation and denaturation and enhancing electron transfer in the modified electrode. The co-immobilization of the enzyme by chitosan-embedding and thioctic-acid-modified NPG covalent bonding was beneficial for improving the catalytic performance and stability of the enzyme-modified electrode. Ferrocene methanol (Fm) was used as a redox mediator to accelerate the electron transfer rate of the enzyme-modified electrode. The fabricated biosensor exhibited a wide determination range of 0.1–5 mM, low determination limit of 77.08 μM, and high sensitivity of 9.17 μA mM−1. Furthermore, it possessed good selectivity, repeatability, and stability, and could be used for the determination of glycerol in real wine samples. This work provides a simple and novel method for the construction of biosensors, which may be helpful to the application of enzymatic biosensors in different determination scenarios.

Research Progress of UiO-66-Based Electrochemical Biosensors

UiO-66, as a member of the MOFs families, is widely employed in sensing, drug release, separation, and adsorption due to its large specific surface area, uniform pore size, easy functionalization, and excellent stability. Especially in electrochemical biosensors, UiO-66 has demonstrated excellent adsorption capacity and response signal, which significantly improves the sensitivity and specificity of detection. However, the existing application research remains in its infancy, lacking systematic methods, and recycling utilization and exclusive sensing of UiO-66 still require further improvement. Therefore, one of the present research objectives is to explore the breakthrough point of existing technologies and optimize the performance of UiO-66-based electrochemical biosensors (UiO-66-EBs). In this work, we summarized current experimental methods and detection mechanisms of UiO-66-EBs in environmental detection, food safety, and disease diagnosis, analyzed the existing problems, and proposed some suggestions to provide new ideas for future research.