3D-printed electrochemical glucose device with integrated Fe(II)-MOF nanozyme

Two Birds with One Stone: Fe-DNA nanospheres produced via coordination-propelled self-assembly with excellent peroxidase-like property for versatile ratiometric fluorescent assay and cellular imaging

Exploring novel versatile nanozymes for multi-signal biosensing and cellular application is one of the most promising directions to meet the diversified requirements in this field. Herein, by harnessing coordination-propelled self-assembly between Fe (II) and DNAs, we prepared Fe-DNA nanospheres (Fe-DNA NSs) via a cost-effective one-step hydrothermal method, and pioneered the application of its excellent POD-mimicking property to fluorescent substrates. Initially, we investigated its enzyme-like activity using TMB as canonical colorimetric substrate and screened its catalytic oxidation effects towards different fluorescent substrates, such as T-HCl, AR, OPD and Sc, respectively. Afterwards, by virtue of the contrary fluorescent changes of Sc (decreased FI465) and OPD (increased FI562) and the cooperative effects of FRET/IFE between them, we devised the first universal Fe-DNA nanospheres-based ratiometric fluorescent (RF) platform. Taking H2O2 and glucose as model targets, two RF biosensors based on the alternative direct-nanozyme-catalysis and enzyme/nanozyme-tandem-catalysis were rationally fabricated, respectively. And we further exploited them to evaluate the quality of commercial contact lens care solution, and sensitively determine the blood glucose level of human. Moreover, corresponding cytotoxicity experiments adequately proved the superior biocompatibility of Fe-DNA NSs over most inorganic nanozymes. Furthermore, taking Cy5-labelled A20 strands as templates, we synthesized small-sized (∼60 nm) Fe-DNA fluorescent nanozyme and achieved efficient cellular delivery/imaging. This work not only offered a valid prototype for operating multi-signal-responsive nanozymatic biosensors, but also opened unique avenues for the bio-applications of nucleic acids-originated fluorescent nanozymes in cellular imaging and biotherapy.

Lab-on-a-Scalpel: Medical Tool Incorporating a Disposable Fully 3D-Printed Electrochemical Cell Promoting Drop-Volume Chemical Analysis in the Operating Theater

Surgical operations are intricate and invasive procedures that require continuous monitoring of the patient's biochemical profile. Point-of-care testing would allow healthcare professionals to identify abnormalities and make the necessary interventions to minimize the risk of complications and ensure patient safety. To this end, we report the development of a disposable and compact fully 3D-printed electrochemical cell incorporated into a medical scalpel (Lab-on-a-Scalpel), aiming to promote on-site (electro)chemical analysis in the operating theater. This multifunctional device minimizes the number of instruments needed during surgery and can be fabricated on-demand by using a desktop-sized 3D printer at a very low cost. The performance of the Lab-on-a-Scalpel sensing device was evaluated over various electrochemical techniques (cyclic voltammetry, amperometry, and differential pulse voltammetry) and different setups (stirring, drop-volume analysis, polarization potentials, etc.) for the determination of epinephrine. Results showed attractive analytical figures-of-merit, with the limit of detection (LOD) reaching 0.13 μM, and high accuracy in recovery studies conducted on artificial blood samples. Our findings suggest that Lab-on-a-Scalpel is a valuable tool that enables near-patient diagnostics with a minimum sample volume and holds promise to become an essential tool for robotic-assisted surgery.

3D-printed electrodes for electrochemical detection of environmental analytes

Environmental monitoring faces increasing demands for rapid, sensitive, and cost-effective analytical methods to detect various pollutants. Three-dimensional (3D) printing technology has emerged as a transformative approach for fabricating electrochemical sensors, offering unprecedented flexibility in electrode design and potential for customization. This comprehensive review examines recent advances in 3D-printed electrochemical sensors for environmental analysis, focusing on manufacturing technologies, materials development, and surface modification strategies. We analyze various printing approaches, including fused deposition modeling, stereolithography, and selective laser melting, discussing their relative advantages and limitations for electrode fabrication. The review explores conductive materials development, from carbon-based composites to novel metal-containing filaments, and examines crucial surface modification techniques that enhance sensor performance. Key applications in environmental monitoring are evaluated, including the detection of heavy metals, pathogens, antibiotics, and organophosphates, with particular attention to analytical performance metrics and real-world applicability. Technical challenges are critically assessed, including limitations in printing resolution, material conductivity, and long-term stability. The review concludes by identifying promising research directions, such as the integration of advanced materials and the development of automated manufacturing processes, highlighting opportunities for improving sensor performance and commercial viability in environmental monitoring applications.

Optimizing the Construction and Activation of 3D-Printed Electrochemical Sensors: An Experimental Design Approach for Simultaneous Electroanalysis of Paracetamol and Caffeine

This work presents an optimization of the construction, treatment, and activation of 3D-printed electrochemical sensors (E-3D). For this, was used a 23-full factorial design examining three key variables at two levels: electrode height, electrode diameter, and printing speed. Moreover, it evaluates various physical, chemical, and electrochemical methods to treat and activate the E-3D surface. The techniques of electrochemical impedance spectroscopy and cyclic voltammetry (CV) shows that the sequential physical, chemical, and electrochemical treatments lead to the highest treatment efficiency and activation. Raman spectroscopy and atomic force microscopy characterize untreated and treated E-3D sensor surfaces. The optimal treatment and activation methodology was applied to the electroanalysis of paracetamol (PAR) and caffeine (CAF) simultaneously using CV and differential pulse anodic stripping voltammetry (DPASV). DPASV measurements reveal limits of detection of 0.44 and 0.58 μmol L-1 in a 0.5 mol L-1 H2SO4 medium for PAR and CAF, respectively, with the treated and activated E-3D sensor. The principal achievement of this work was emphasizing the critical role of surface treatment and activation in enhancing the performance of the developed electrodes, thereby advancing technological applications of 3D-printed electrochemical sensors.

Shifting paradigm in electrochemical biosensing matrices comprising metal organic frameworks and their composites in disease diagnosis

Metal Organic Frameworks (MOFs) are an evolving category of crystalline microporous materials that have grabbed the research interest for quite some time due to their admirable physio-chemical properties and easy fabrication methods. Their enormous surface area can be a working ground for innumerable molecular adhesions and site for potential sensor matrices. They have been explored in the last decade for incorporation in electrochemical sensor matrices as diagnostic solutions for a plethora of diseases. This review emphasizes on some of the recent advancements in the area of MOF-based electrochemical biosensors with focus on various important diseases and their significance in upgrading the sensor performance. It summarizes MOF-based biosensors for monitoring biomarkers relevant to diabetes, viral and bacterial sepsis infections, neurological disorders, cardiovascular diseases, and cancer in a wide range of real matrices. The discussion has been supplemented with extensive tables elaborating recent trends in the field of MOF-composite probe fabrication strategies with their respective sensing parameters. The article sums up the future scope of these materials in the field of biosensors and enlightens the reader with recent trends for future research scope. This article is categorized under: Diagnostic Tools > Biosensing Diagnostic Tools > Diagnostic Nanodevices.

Immobilizing nanozymes on 3D-printed metal substrates for enhanced peroxidase-like activity and trace-level glucose detection

The prevalence of 3D-printed portable biomedical sensing devices, which are fashioned mainly from plastic and polymer materials, introduces a pressing concern due to their limited reusability and consequential generation of substantial disposable waste. Considering this, herein, we pioneered a ground-breaking advancement, i.e., a 3D-printed metal substrate-based enzyme. Our inventive methodology involved the synthesis of a thermally degraded Fe-based metal-organic framework, DEG 500, followed by its deposition on a 3D-printed metal substrate composed of Ti-Al-V alloy. This novel composite exhibited remarkable peroxidase-like activity in a range of different temperatures and pH, coupled with the ability to detect glucose in real-world samples such as blood and fruit juices. The exceptional enzymatic behaviour was attributed to the diverse iron (Fe) oxidation states and the presence of oxygen vacancies, as evidenced through advanced characterization techniques. Fundamentally, we rigorously explored the mechanistic pathway through controlled studies and theoretical calculations, culminating in a transformative stride toward more sustainable and effective biomedical sensing practices.