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Laser scribing is a technique that converts carbon-rich precursors into 3D-graphene nanomaterial via direct, single-step, and maskless laser writing in environmental conditions and using a scalable approach. It allows simple, fast, and reagentless production of a promising material with outstanding physicochemical features to create novel electrochemical sensors and biosensors. This review addresses different strategies for fabricating laser-scribed graphene (LSG) devices and their association with nanomaterials, polymers, and biological molecules. We provide an overview of their applications in environmental and health monitoring, food safety, and clinical diagnosis. The advantages of their integration with machine learning models to achieve low bias and enhance accuracy for data analysis is also addressed. Finally, in this review our insights into current challenges and perspectives for LSG electrochemical sensors are presented.

The possibility of fast, reliable, and sensitive (μmol L À 1 ) quantification of acetaminophen (AAP) directly in saliva and sweat was demonstrated in the pH range of 4 to 7 using a new userfriendly and cost-effective graphite screen-printed electrode (SPE) modified with 2-3 nm diameter alpha-nickel-cerium hydroxide nanoparticles. The nanoparticles (NPs) were fully characterized by transmission electron microscopy (TEM, HRTEM and STEM), XRD, and the electrochemical conditions for AAP analysis optimized, pushing down the limit of detection with good selectivity. The possibility of real-time measurements of AAP was demonstrated by carrying out experiments directly in biofluids, without significant interference from species such as lactate, glucose, ascorbic and uric acid usually present in this kind of samples. This is the first report combining the catalytic properties and easy incorporation of alpha-nickel-cerium hydroxide nanoparticles into graphite ink to prepare an SPE for AAP electrochemical detection in secreting body fluids. The α-Ni 0.9 Ce 0.1 (OH) 2 SPE features good accuracy and selectivity, fast response, good accuracy and selectivity, as well as low reagent consumption for determination of AAP in real saliva and sweat samples.

Multifunctional nanomaterials have been attracting increasing attention as solutions to the existing challenges in energy systems and sensing technologies. In this regard, multifunctional NiVCe-layered double hydroxide (NiVCe-LDH) nanoparticles were synthesized by the modified sol-gel method. The analysis of this material demonstrated excellent potential for its utilization as electrode materials for hybrid supercapacitor, oxygen evolution reaction (OER), and sensor applications. The NiVCe-LDH nanoparticles delivered a specific charge of 740 C g−1 at 10 A g−1 and decent rate performance (charge retention of 68.7% at 100 A g−1), showing excellent prospects as electrode material for hybrid energy storage devices. In addition, NiVCe-LDH nanoparticles have also been successfully applied as a proof-of-concept for OER, as confirmed by their low Tafel slope of 47 mV dec−1. Finally, trimetallic NiVCe-LDH-based screen-printed electrodes were developed for the sensing of hydrogen peroxide directly in a real complex mouthwash sample, achieving a satisfactory recovery value of around 98% using a fast and simple batch injection analysis procedure. These results allow us to predict the great potential of this trimetallic hydroxide for building electrochemical sensors with good perspectives as electroactive material for OER processes and energy storage technologies.

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