A Dual-Mode NADH Biosensor Based on Gold Nanostars Decorated CoFe2 Metal-Organic Frameworks to Reveal Dynamics of Cell Metabolism

Rational Design of MOF-Based Multifunctional Bio-Nanoreactor for Efficient Detection and Photo-Degradation of Chloramphenicol

Food safety have received increasing attention in recent years, and rapid detection and thorough removal of organic contaminants is an important part of food safety control. In this work, a novel multi-functional photo-enzymatic nanoreactor HRP@Fe-NU-1003 is developed through the co-immobilization of horseradish peroxidase (HRP) and FeCl2 on a photosensitive metal-organic frameworks (MOF) NU-1003. The bio-nanocluster can serve as an efficient biosensor in the detection of chloramphenicol (CAP), with a detection limit of 15.38 pg mL-1, which is 62 times greater than that of the conventional HRP- enzyme-linked immunosorbent assay method. Besides its detecting capability, the nanoreactor also exhibits high efficiency in the photocatalytic degradation of CAP, which can remove 50 µg mL-1 of CAP thoroughly within 30 min, and the mineralization efficiency of CAP reaches 61%. In this material, Fe-NU-1003 not only acts as a protecting shell to prevent HRP from deactivation, but improves detecting sensitivity and photocatalytic performance. Mechanism studies show that FeCl2 enhances its photocatalytic performance through promoting electron (e-)-hole (h+) separation and photocurrent transfer. More importantly, the heterogeneous material possesses high stability and can be recycled at least five rounds while its photocatalytic performance maintained at a high level. This strategy provides a new approach for the detection and degradation of pollutants.

Photoactivated Nanowires as In Situ Transmembrane Electron Tunnels for Dual-Model Monitoring of Intracellular Biomarkers

The insertion of a single nanoelectrode into the cell or fluorescence detection has enabled the nondestructive tracking of intracellular biomarkers. However, the reliance on extremely expensive micromanipulators or intricate fluorescent probes has limited their widespread application. To address this challenge, we propose a novel strategy that employs modified multiwalled carbon nanotubes (MWCNTs) as artificial transmembrane electron tunnels. These MWCNTs can be spontaneously and nondestructively semiembedded within cells while exhibiting remarkable conductivity. When the photosensitive electrodes on the cell surface are illuminated, photogenerated electron-hole pairs are produced. The holes can enter the cell through the nanowires, thus promoting oxidation reactions with target molecules and generating real-time electrical signals for monitoring intracellular biomarkers. Meanwhile, the engineered recognition element on the nanowire transitions to an excited state and subsequently returns to the ground state through electrochemiluminescence (ECL), enabling in situ visualization of intracellular biomarkers. This groundbreaking approach not only eliminates the need for micromanipulators and fluorescent probes but also enables simultaneous electrical and optical monitoring of intracellular biomarker levels, significantly reducing false-positive risks. This innovation was validated to be feasible using NADH as an intracellular target molecule, marking a shift in intracellular sensing strategies.

A paper-based SERS/colorimetry substrate for reliable detection

For on-site analysis, the combination of surface enhanced Raman scattering (SERS) and colorimetry, as a dual-mode detection, can effectively improve the accuracy of detection, and reduce the influence of instrument fluctuation, which greatly improves the accuracy and reliability of the results. However, the preparation of SERS/colorimetry substrates are usually time-consuming and costly, which limits their practical applications. In this paper, a hydrophobic paper-based SERS/colorimetry substrate can be prepared by a simple spraying method. The hydrophobicity is introduced by the structures formed with polydimethylsiloxane and polymethylmethacrylate, which leads to high detection sensitivity due to its enrichment effect. Moreover, the electrostatic interaction between Ag nanoparticles and the analytes further enhances the performance of SERS and colorimetry in detection of thiram and aspartame. It also provides a new method for the detection of aspartame with colorimetry. Finally, the detection limits of SERS and colorimetry for thiram and aspartame are 0.1 mg/L and 0.1 g/L, 1 mg/L and 0.1 g/L, respectively. The paper-based SERS/colorimetry substrate makes the results more reliable through dual-mode detection, which shows great potential in the detection of real samples.

Advances and Future Trends in Nanozyme-Based SERS Sensors for Food Safety, Environmental and Biomedical Applications

Nanozymes, a kind of nanoparticles with enzyme-mimicking activities, have attracted considerable attention due to their robust catalytic properties, ease of preparation, and resistance to harsh conditions. By combining nanozymes with surface-enhanced Raman spectroscopy (SERS) technology, highly sensitive and selective sensors have been developed. These sensors are capable of detecting a wide range of analytes, such as foodborne toxins, environmental pollutants, and biomedical markers. This review provides an overview of recent advancements in the synthesis and surface modification of nanozymes, highlighting their ability to mimic multiple enzymes and enhance catalytic performance. In addition, we explore the development and applications of nanozyme-based SERS sensors in food contaminants, environmental pollutants, and biomedical markers. The review concludes with perspectives and challenges facing the field, involving the need for deeper understanding of nanozyme principles and mechanisms, development of standardized systems for characterization, and the engineering of nanozymes with tailored properties for specific applications. Finally, we discuss the potential for integrating various techniques with nanozymes to create multi-modal detection platforms, paving the way for the next generation of analytical tools in the fields of food safety, environmental monitoring, and biomedical diagnostics.

Dynamic Real-Time Biosensing Enabled Biorhythm Tracking for Psychiatric Disorders

This review article explores the transformative potential of dynamic, real-time biosensing in biorhythm tracking for psychiatric disorders. Psychiatric diseases, characterized by a complex, heterogeneous, and multifactorial pathophysiology, pose challenges in both diagnosis and treatment. Common denominators in the pathophysiology of psychiatric diseases include disruptions in the stress response, sleep-wake cycle, energy metabolism, and immune response: all of these are characterized by a strong biorhythmic regulation (e.g., circadian), leading to dynamic changes in the levels of biomarkers involved. Technological and practical limitations have hindered the analysis of such dynamic processes to date. The integration of biosensors marks a paradigm shift in psychiatric research. These advanced technologies enable multiplex, non-invasive, and near-continuous analysis of biorhythmic biomarkers in real time, overcoming the constraints of conventional approaches. Focusing on the regulation of the stress response, sleep/wake cycle, energy metabolism, and immune response, biosensing allows for a deeper understanding of the heterogeneous and multifactorial pathophysiology of psychiatric diseases. The potential applications of nanobiosensing in biorhythm tracking, however, extend beyond observation. Continuous monitoring of biomarkers can provide a foundation for personalized medicine in Psychiatry, and allow for the transition from syndromal diagnostic entities to pathophysiology-based psychiatric diagnoses. This evolution promises enhanced disease tracking, early relapse prediction, and tailored disease management and treatment strategies. As non-invasive biosensing continues to advance, its integration into biorhythm tracking holds promise not only to unravel the intricate etiology of psychiatric disorders but also for ushering in a new era of precision medicine, ultimately improving the outcomes and quality of life for individuals grappling with these challenging conditions.

Recent advances of MOF-based SERS substrates in quantitative analysis of food contaminants: a review

Advancements in food-contaminant detection technologies can significantly improve food safety and human health. Surface-enhanced Raman spectroscopy (SERS) has become the preferred analytical method for food-safety detection owing to its numerous advantages, which include unique 'molecular fingerprinting' features, high sensitivity, rapid responses, and non-invasive characteristics. Raman-signal enhancements rely heavily on high-performance SERS substrates. In recent years, metal-organic framework (MOF)-based SERS substrates have gained attention as promising candidates for developing SERS technologies owing to their distinctive structures and functions. This review comprehensively examines recent advances in MOF-based SERS substrates, focusing on the main role of MOFs in SERS substrates as well as their typical categories and structures, construction methods, and representative applications in food-contaminant detection. First, the primary roles of MOFs in SERS substrates are briefly introduced. Next, a comprehensive overview of the typical categories and structures of MOF-based SERS substrates is discussed. Subsequently, a fundamental view of the general construction methods for MOF-based SERS substrates is presented. Next, the main applications of MOF-based SERS substrates for food-contaminant detection are summarised. Finally, challenges and perspectives, including improvements in SERS performance and stability, and the unification of SERS mechanisms, are addressed and discussed.

Microenvironment-sensitive nanozymes for tissue regeneration

Tissue defect is one of the significant challenges encountered in clinical practice. Nanomaterials, including nanoparticles, nanofibers, and metal-organic frameworks, have demonstrated an extensive potential in tissue regeneration, offering a promising avenue for future clinical applications. Nonetheless, the intricate landscape of the inflammatory tissue microenvironment has engendered challenges to the efficacy of nanomaterial-based therapies. This quandary has spurred researchers to pivot towards advanced nanotechnological remedies for overcoming these therapeutic constraints. Among these solutions, microenvironment-sensitive nanozymes have emerged as a compelling instrument with the capacity to reshape the tissue microenvironment and enhance the intricate process of tissue regeneration. In this review, we summarize the microenvironmental characteristics of damaged tissues, offer insights into the rationale guiding the design and engineering of microenvironment-sensitive nanozymes, and explore the underlying mechanisms that underpin these nanozymes' responsiveness. This analysis includes their roles in orchestrating cellular signaling, modulating immune responses, and promoting the delicate process of tissue remodeling. Furthermore, we discuss the diverse applications of microenvironment-sensitive nanozymes in tissue regeneration, including bone, soft tissue, and cartilage regeneration. Finally, we shed our sights on envisioning the forthcoming milestones in this field, prospecting a future where microenvironment-sensitive nanozymes contribute significantly to the development of tissue regeneration and improved clinical outcomes.

Multimodal biosensing systems based on metal nanoparticles

Biosensors are currently among the most commonly used devices for analysing biomarkers and play an important role in environmental detection, food safety, and disease diagnosis. Researchers have developed multimodal biosensors instead of single-modal biosensors to meet increasing sensitivity, accuracy, and stability requirements. Metal nanoparticles (MNPs) are beneficial for preparing core probes for multimodal biosensors because of their excellent physical and chemical properties, such as easy regulation and modification, and because they can integrate diverse sensing strategies. This review mainly summarizes the excellent physicochemical properties of MNPs applied as biosensing probes and the principles of commonly used MNP-based multimodal sensing strategies. Recent applications and possible improvements of multimodal biosensors based on MNPs are also described, among which on-site inspection and sensitive detection are particularly important. The current challenges and prospects for multimodal biosensors based on MNPs may provide readers with a new perspective on this field.

Fabrication of a Novel Optical Glucose Biosensor Using Copper(II) Neocuproine as a Chromogenic Oxidant and Glucose Dehydrogenase-Immobilized Magnetite Nanoparticles

This study describes a novel optical glucose biosensor based on a colorimetric reaction between reduced nicotinamide adenine dinucleotide (NADH) and a copper(II) neocuproine complex ([Cu(Nc)2]2+) as a chromogenic oxidant. An enzymatic reaction takes place between glucose and glucose dehydrogenase (GDH)-chitosan (CS) immobilized on silanized magnetite nanoparticles (CS@SiO2@Fe3O4) in the presence of coenzyme NAD+. The oxidation of glucose to gluconolactone via the immobilized enzyme is coupled with the reduction of NAD+ to NADH at the same time. After the separation of GDH-immobilized SiO2@Fe3O4 with a magnet, the enzymatically produced NADH chemically reduces the chromogenic oxidant cupric neocuproine to the cuprous chelate. Thus, the glucose biosensor is fabricated based on the measurement of the absorbance of the formed yellow-orange complex ([Cu(Nc)2]+) at 450 nm. The obtained results show that the colorimetric biosensor has a wide linear response range for glucose, between 1.0 and 150.0 μM under optimized conditions. The limit of detection and limit of quantification were found to be 0.31 and 1.02 μM, respectively. The selectivity properties of the fabricated biosensor were tested with various interfering species. This biosensor was applied to various samples, and the obtained results suggest that the fabricated optical biosensor can be successfully used for the selective and sensitive determination of glucose in real samples.

Signal Amplification Strategy Design in Nanozyme-Based Biosensors for Highly Sensitive Detection of Trace Biomarkers

Nanozymes show great promise in enhancing disease biomarker sensing by leveraging their physicochemical properties and enzymatic activities. These qualities facilitate signal amplification and matrix effects reduction, thus boosting biomarker sensing performance. In this review, recent studies from the last five years, concentrating on disease biomarker detection improvement through nanozyme-based biosensing are examined. This enhancement primarily involves the modulations of the size, morphology, doping, modification, electromagnetic mechanisms, electron conduction efficiency, and surface plasmon resonance effects of nanozymes for increased sensitivity. In addition, a comprehensive description of the synthesis and tuning strategies employed for nanozymes has been provided. This includes a detailed elucidation of their catalytic mechanisms in alignment with the fundamental principles of enhanced sensing technology, accompanied by the presentation of quantitatively analyzed results. Moreover, the diverse applications of nanozymes in strip sensing, colorimetric sensing, electrochemical sensing, and surface-enhanced Raman scattering have been outlined. Additionally, the limitations, challenges, and corresponding recommendations concerning the application of nanozymes in biosensing have been summarized. Furthermore, insights have been offered into the future development and outlook of nanozymes for biosensing. This review aims to serve not only as a reference for enhancing the sensitivity of nanozyme-based biosensors but also as a catalyst for exploring nanozyme properties and their broader applications in biosensing.

Nanozymes towards Personalized Diagnostics: A Recent Progress in Biosensing

This review highlights the recent advancements in the field of nanozymes and their applications in the development of point-of-care biosensors. The use of nanozymes as enzyme-mimicking components in biosensing systems has led to improved performance and miniaturization of these sensors. The unique properties of nanozymes, such as high stability, robustness, and surface tunability, make them an attractive alternative to traditional enzymes in biosensing applications. Researchers have explored a wide range of nanomaterials, including metals, metal oxides, and metal-organic frameworks, for the development of nanozyme-based biosensors. Different sensing strategies, such as colorimetric, fluorescent, electrochemical and SERS, have been implemented using nanozymes as signal-producing components. Despite the numerous advantages, there are also challenges associated with nanozyme-based biosensors, including stability and specificity, which need to be addressed for their wider applications. The future of nanozyme-based biosensors looks promising, with the potential to bring a paradigm shift in biomolecular sensing. The development of highly specific, multi-enzyme mimicking nanozymes could lead to the creation of highly sensitive and low-biofouling biosensors. Integration of nanozymes into point-of-care diagnostics promises to revolutionize healthcare by improving patient outcomes and reducing costs while enhancing the accuracy and sensitivity of diagnostic tools.