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Dopamine is an essential neurotransmitter for daily cognitive functions controlling many neurophysiological processes including memory, cognition, and physical control. Development of analytical methods and sensors to detect dopamine is important for health monitoring and neurological research. This review provides an overview of recent advances in the development of electrochemical catalytic biosensors based on enzyme and enzyme-mimetic materials and discusses their potential applications for measurements of dopamine in biological fluids. The first part of the review summarizes and critically assesses the different types of enzymes and enzyme mimetic materials that can be used to catalytically convert dopamine, followed by a discussion of the biosensor’s fabrication, key design parameters, and detection mechanism on various electrode platforms ranging from single-use screen-printed electrodes to microneedles and implantable microelectrodes. The second part provides examples of measurements of dopamine in biological samples, including saliva, urine, serum, cell cultures, and brain tissue. We conclude with a summary of advantages and limitations of these devices in the clinical field, and an outlook to future research towards the implementation and broader adoption of electrochemical biosensors in neurophysiology, pharmacology, and the clinical field.

 

Electrochemical biosensors have the potential to provide rapid and inexpensive diagnostics while moving clinical testing from centralized labs to point-of-care (POC) applications. Conductive materials functionalized with bioreceptors that remain stable and functional for measurements in real-world conditions are essential for the fabrication of electrochemical biosensors, and carbon-based nanomaterials provide the electrical, chemical, structural, and mechanical features that make them suitable for POC devices. This review details the most recent developments in the use of carbon-based nanostructures, with a focus on one-dimensional carbon nanotubes, two-dimensional graphene, and graphene oxide, their interface with biological receptors, deposition on portable, flexible, and wearable substrates, and integration on low-cost platforms for detection of clinical biomarkers. The large-scale manufacturing and implementation of microneedles as implantable and electronic tattoos as wearable devices for on-skin diagnostics, and lab-on-mouth platforms as well as the interface with mobile technologies and their potential implementation for remote POC monitoring and decentralized healthcare through cloud processing and the internet of things (IoT) are discussed with examples of applications. The review concludes with an overview of the regulatory perspectives and future trends, challenges, and opportunities for commercialization and translation of these technologies from the research lab to practice, as useful diagnostic tools for remote monitoring of patient health conditions. 

Heavy metal contamination is one of the leading causes of water pollution, with known adverse effects on human health and the environment. This work demonstrates a novel custom-made 3D printable eco-friendly hydrogel and fabrication process that produces stable biocompatible adsorbents with the ability to capture and remove heavy metals from aqueous environments quickly and economically. The 3D printable ink contains alginate, gelatin, and polyethyleneimine (PEI), which binds heavy metals through primary and secondary amine side chains favoring heavy metal adsorption. The ink's rheological properties are optimized to create mechanically stable constructs, in the form of 3D-printed tablets, fabricated entirely by printing. The optimized tablets have high porosity and accessible surface area with multiple binding sites for heavy metal ion adsorption while the printing process enables rapid and affordable production with the potential for scale-up. The results demonstrate the contribution of hydrogel composition and rheology in determining the printability, stability, and heavy metal binding characteristics of the hydrogel, and indicate the critical role of the PEI in increasing stability of the printed construct, in addition to its metal binding properties. The highest removal capacity was obtained for copper, followed by cadmium, cobalt, and nickel ions. In the optimized formulation, each hydrogel tablet removed 60% from 100 ppm copper in 5 h and up to 98% in 18 h. For more concentrated solutions (1000 ppm), ∼25% of copper was removed in 18 h. The printed tablets are stable, robust, and can be produced in a single simple step from inexpensive biomaterials. The ink's tunability, excellent printability, and stability offer a universally applicable procedure for creating hydrogel-based structures for environmental remediation. These unique capabilities open new avenues for manufacturing tailor-made constructs with integrated functionality for water treatment and environmental applications. 

Theranostic nanoparticles (NPs) which provide both therapeutic and diagnostic capabilities have potential to fundamentally change biomedical sciences and improve disease diagnostics and therapy. This review summarizes the recent advances in the development of ceria NPs (CeNPs) therapeutics with combined free radical scavenging activity and biosensing functions as a promising class of theranostic probes in biomedicine. The unique physicochemical properties of CeNPs including the antioxidant, anticancer and anti-inflammatory properties are discussed in relation to their therapeutic efficacy in disease models including neurodegenerative diseases, anti-inflammatory, hypoxic damage, ischemia-reperfusion. The potential to combine the antioxidant properties with sensing functions to achieve synergistic therapeutic and biosensing functions is highlighted with a focus on personalized medicine and next generation therapy. The current state-of-the-art, challenges and opportunities for future development of CeNPs as active theranostic probes in biomedicine are also discussed.

 

The presence of contaminants of emerging concerns (CECs) such as pharmaceuticals and personal care products, endocrine disrupting compounds (EDCs), per/poly‐fluorinated substances (PFAS), pesticides, and nanomaterials poses significant challenges to the environment and human health. This review discusses the current status of electrochemical sensing methods and their potential as low‐cost analytical platforms for the detection and characterization of emerging contaminants. Recent developments in advanced materials and fabrication techniques such as electrophoretic deposition, layer‐by‐layer deposition, roll‐to‐roll and 3D printing techniques, and the scalable manufacturing of low‐cost portable electrochemical devices are discussed. Examples of detection mechanisms, electrode modification procedures, device configuration, and their performance along with recent developments in fundamental electrochemistry, particularly nanoimpact methods, are provided to demonstrate the capabilities of these methods for the environmental monitoring of CECs. Finally, a critical discussion of future research needs, detection challenges, and opportunities is provided to demonstrate how electrochemistry can be used to advance field monitoring of these chemicals. These methods can be used as complementary or alternative methods to the currently used laboratory‐based analytical instrumentation to facilitate large‐scale studies and manage risks associated with the presence of CECs in the environment and other matrices.

 

Nanoelectrochemistry allows for the investigation of the interaction of per‐ and polyfluoroalkyl substances (PFASs) with silver nanoparticles (AgNPs) and the elucidation of the binding behaviour of PFASs to nanoscale surfaces with high sensitivity. Mechanistic studies supported by single particle collision electrochemistry (SPCE), spectroscopic and density functional theory (DFT) calculations indicate the capability of polyfluorooctane sulfonic acid (PFOS), a representative PFAS, to selectively bind and induce aggregation of AgNPs. Single‐particle measurements provide identification of the “discrete” AgNPs agglomeration (e.g. 2–3 NPs) formed through the inter‐particles F−F interactions and the selective replacement of the citrate stabilizer by the sulfonate of the PFOS. Such interactions are characteristic only for long chain PFAS (‐SO₃⁻) providing a means to selectively identify these substances down to ppt levels. Measuring and understanding the interactions of PFAS at nanoscale surfaces are crucial for designing ultrasensitive methods for detection and for modelling and predicting their interaction in the environment.

 

Nanoelectrochemistry allows for the investigation of the interaction of per‐ and polyfluoroalkyl substances (PFASs) with silver nanoparticles (AgNPs) and the elucidation of the binding behaviour of PFASs to nanoscale surfaces with high sensitivity. Mechanistic studies supported by single particle collision electrochemistry (SPCE), spectroscopic and density functional theory (DFT) calculations indicate the capability of polyfluorooctane sulfonic acid (PFOS), a representative PFAS, to selectively bind and induce aggregation of AgNPs. Single‐particle measurements provide identification of the “discrete” AgNPs agglomeration (e.g. 2–3 NPs) formed through the inter‐particles F−F interactions and the selective replacement of the citrate stabilizer by the sulfonate of the PFOS. Such interactions are characteristic only for long chain PFAS (‐SO₃⁻) providing a means to selectively identify these substances down to ppt levels. Measuring and understanding the interactions of PFAS at nanoscale surfaces are crucial for designing ultrasensitive methods for detection and for modelling and predicting their interaction in the environment.