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2D layered molybdenum disulfide (MoS

The most significant advances in food analysis using microchip electrophoresis (ME) technology will be discussed in this book chapter, covering the works published from 2009 to 2019, which will be organized in three sections based on the detection mode employed: electrochemical and fluorescence detection, and bioanalytical-based approaches. The most innovative methodologies, relevant applications, and latest advances in instrumentation to achieve a truly portable lab-o- -a-chip will be discussed. Commercial instruments will also be briefly mentioned as a demonstration of the maturity of ME technology.

Herein we report the coating of visible light-driven polycaprolactone (PCL) based micromotors with an anti-biofouling poly lactic-co-glycolic acid (PLGA) layer for effective navigation and detoxification in blood samples. The micromotors encapsulate CdSe@ZnS quantum dots as photoresponsive materials and a Fe3O4 nanoparticle patch to promote electron transfer and reaction with glucose present in the media for diffusiophoretic propulsion in diluted blood. The coating of the micromotor with the PLGA layer prevents red blood cell adhesion and protein adsorption due to the creation of a highly efficient hydration layer. This results in an enhanced speed and efficient operation for enhanced toxin removal as compared with the bare PCL micromotors. Hemolysis and MTT assays along with no platelets aggregation revealed the high biocompatibility of the micromotors with living cells. Effective adsorptive removal of two relevant toxins, sepsis associated Escherichia coli O111:B4 toxin and snake venom α-bungarotoxin from blood is achieved with the PLGA micromotors. The new developments illustrated here represent one step forward in the use of light-driven micromotors for biomedical applications.

In this work, we study the interaction of graphdiyne oxide (GDYO)-, graphene oxide (GO)-, or black phosphorous (BP)-wrapped Janus micromotors using a model system relying on a fluorescence-labeled affinity peptide, which is released upon specific interaction with a target Cholera Toxin B. Such ON-OFF-ON system allows mimicking similar processes occurring at (bio)-interfaces and to study the related sorption and desorption kinetics. The distinct surface properties of each nanomaterial play a critical role in the loading/release capacity of the peptide, greatly influencing the release profiles. Sorption obeys a second-order kinetic model using the two-dimensional (2D) nanomaterials in connection with micromotors, indicating a strong influence of chemisorption process for BP micromotors. Yet, release kinetics are faster for GDYO and GO nanomaterials, indicating a contribution of π and hydrophobic interactions in the probe sorption (Cholera Toxin B affinity peptide) and target probe release (in the presence of Cholera Toxin B). Micromotor movement also plays a critical role in such processes, allowing for efficient operation in low raw sample volumes, where the high protein content can diminish probe loading/release, affecting the overall performance. The loading/release capacity and feasibility of the (bio)-sensing protocol are illustrated in Vibrio cholerae and Vibrio parahaemolyticus bacteria cultures as realistic domains. The new concept described here holds considerable promise to understand the interaction of micromotor with biological counterparts in a myriad of biomedical and other practical applications, including the design of novel micromotor-based sensors.

A novel benchtop approach to fabricate xurography-enabled thermally transferred (XTT) carbon nanomaterial-based electrochemical sensors is proposed. Filtered nanomaterial (NM) films were transferred from Teflon filters to polyethylene terephthalate-ethylene vinyl acetate (PET-EVA) substrates by a temperature-driven approach. Customized PET-EVA components were xurographically patterned by a cutting plotter. The smart design of PET-EVA films enabled us to selectively transfer the nanomaterial to the exposed EVA side of the substrate. Hence, the substrate played an active role in selectively controlling where nanomaterial transfer occurred allowing us to design different working electrode geometries. Counter and reference electrodes were integrated by a stencil-printing approach, and the whole device was assembled by thermal lamination. To prove the versatility of the technology, XTT materials were exclusively made of carbon black (XTT-CB), multiwalled carbon nanotubes (XTT-MWCNTs), and single-walled carbon nanotubes (XTT-SWCNTs). Their electrochemical behavior was carefully studied and was found to be highly dependent on the amount and type of NM employed. XTT-SWCNTs were demonstrated to be the best-performing sensors, and they were employed for the determination of l-tyrosine (l-Tyr) in human plasma from tyrosinemia-diagnosed patients. High analytical performance toward l-Tyr (linear range of 0.5-100 μM, LOD = 0.1 μM), interelectrode precision (RSD

WS2/Pt and MoS2/Pt bubble propelled micromotors are used as "on-the-fly" sensing platforms in bioassays, using a highly selective affinity peptide probe for "OFF-ON" detection of Escherichia coli as a model endotoxin. The different outer micromotor surface characteristics play an important role in the sensing performance. The relatively high outer surface of WS2/Pt micromotors results in a 3.5-fold increase in sensitivity compared to MoS2/Pt micromotors due to enhanced peptide probe loading and release. The peptide-modified WS2 micromotors are used as a low-cost and high-throughput approach for the determination of E. coli endotoxin after only 60 s, with a limit of detection of 1.9 ng mL-1 and high selectivity. The method has been validated using spiked samples (tap water, blood serum, and saliva) and bacteria media (blank broth, Staphylococcus aureus, and E. coli). The concept can be extended to the analysis of other (bio)-analytes and easily incorporated into portable instrumentation, holding great promise in a myriad of clinical, environmental, or food-safety applications.

A new fluorescence micromotor-based immunoassay (FMIm) has been developed for procalcitonin (PCT) determination as an early sepsis diagnostic analytical tool. The micromotors combine the high binding capacity of the specific antibodies onto their polymeric polypyrrole outer layer (PPy layer), with their magnetic guidance (Ni layer) and self-propulsion by catalytic generation of oxygen bubbles (PtNP inner layer) to actively recognize the PCT antigen. This FMIm allowed a sensitive (LOD = 0.07 ng mL-1) and direct PCT determination in clinical samples from very low-birth-weight infants (VLBWI) with sepsis suspicion, using small volumes of sample (25 μL) in a clinically relevant range of concentrations (0.5-150 ng mL-1). The good agreement between PCT levels obtained by our micromotor-based method and routine immunofluorescence hospital determination demonstrates the feasibility for the analysis in VLBWI samples and its potential as a point-of-care diagnostic tool for sepsis.

Online coupling of a micromotor-based immunoassay and a microfluidic electrochemical detection was explored as a new approach for C-reactive protein (CRP) determination in serum and preterm neonatal plasma samples with sepsis suspicion. The approach combines the advantages of micromotors (self-fluid mixing capabilities leading to a faster assay in low sample volumes) and electrochemical microfluidic (flow-controlled ultraminiaturized electrochemical detection, high sensitivity, and low-cost) technologies. Both technologies elegantly meet the point of care testing or bed side device requirements such as low analysis times, miniaturization and simplification, and single use. Anti-CRP functionalized micromotors (anti-CRP-rGO(reduced graphene oxide)/Ni/PtNPs (platinum nanoparticles))-based immunoassay coupled to thin layer Au-based electrochemical microfluidics operating at -0.20 V under controlled fluidic detection operations (30 μL min-1) allowed the sensitive (LOD = 0.54 μg/mL) and accurate CRP determination using very low volume preterm neonatal clinical samples (

Micro-/nanorobot technology has developed rapidly in recent years due to their great potential to perform multiple tasks. Here, we develop magnetic microrobots prepared as polycaprolactone/Fe

Micro/nanomotors are nanoscale devices that have been explored in various fields, such as drug delivery, environmental remediation, or biosensing and diagnosis. The use of micro/nanomotors has grown considerably over the past few years, partially because of the advantages that they offer in the development of new conceptual avenues in biosensing. This is due to their propulsion and intermixing in solution compared with their respective static forms, which enables motion-based detection methods and/or decreases bioassay time. This review focuses on the impacts of micro/nanomotors on biosensing research in the last 2 years. An overview of designs for bioreceptor attachment to micro/nanomotors is given. Recent developments have focused on chemically propelled micromotors using external fuels, commonly hydrogen peroxide. However, the associated fuel toxicity and inconvenience of use in relevant biological samples such as blood have prompted researchers to explore new micro/nanomotor biosensing approaches based on biocompatible propulsion sources such as magnetic or ultrasound fields. The main advances in biocompatible propulsion sources for micro/nanomotors as novel biosensing platforms are discussed and grouped by their propulsion-driven forces. The relevant analytical applications are discussed and representatively illustrated. Moreover, envisioning future biosensing applications, the principal advantages of micro/nanomotor synthesis using biocompatible and biodegradable materials are given. The review concludes with a realistic drawing on the present and future perspectives.

The ubiquity and importance of ROS and RNS in cellular signaling, disease development, and death give rise to an outstanding interest in their detection and quantification. Among the analytical techniques available, electrochemical sensors stand out for the detection of ROS/RNS due to their high sensitivity and inherent miniaturization which allows the in situ and real-time detection together with a tunable selectivity due to the different electrochemical behavior of ROS/RNS. Nanomaterial-based enzyme-free electrochemical sensors possess improved sensitivity, selectivity, stability, and unique catalytic activities. In addition, their integration in nanoelectrodes, lab-on-chips, microfluidic systems, and stretchable electrodes allow the determination of ROS/RNS in individual cells, cell organelles, or cell populations, under different experimental conditions hardly accessible using classical detection methods.

Resumen del póster presentado a la XXXVIII Reunión Bienal de la Real Sociedad Española de Química, celebrada en el Palacio de Congresos de Granada, del 27 de junio al 30 de junio de 2022., This work presents an inmunoplatform design for the single and simultaneous determination of two immunoglobulin (Ig) subtypes, specifically IgE and IgG4, considered as reliable markers for the diagnosis and attenuation of food allergy specific to ovalbumin (OVA) (Fig. 1: Schematics for electrochemical immunoassay of the OVA-specific IgE and IgG4). The assay is based on the use of OVA-modified magnetic microbeads bioconjugates for the specific capture of Igs (IgE and IgG4) from serum, which are discriminated in a further step using the specific antibody to the Ig isotype to be detected conjugated with horseradish enzyme. Single or dual amperometric transduction was carried out on (dual) screen-printed carbon electrodes, in the presence of H2O2/hydroquinone system. This approach provides good results in terms of sensitivity (LOD values of 0.003 kU L-1 and 0.0002 μg L-1 for IgE and IgG4, respectively), simplicity and assay time. Both Igs were determined in serum of patients diagnosed with egg allergy with excellent results.