Capacitive immunosensing at gold nanoparticle-decorated reduced graphene oxide electrodes fabricated by one-step laser nanostructuration.

Nanostructured electrochemical biosensors have ushered in a new era of diagnostic precision, offering enhanced sensitivity and specificity for clinical biomarker detection. Among them, capacitive biosensing enables ultrasensitive label-free detection of multiple molecular targets. However, the complexity and cost associated with conventional fabrication methods of nanostructured platforms hinder the widespread adoption of these devices. This study introduces a capacitive biosensor that leverages laser-engraved reduced graphene oxide (rGO) electrodes decorated with gold nanoparticles (AuNPs). The fabrication involves laser-scribed GO-Au3+ films, yielding rGO-AuNP electrodes, seamlessly transferred onto a PET substrate via a press-stamping methodology. These electrodes have a remarkable affinity for biomolecular recognition after being functionalized with specific bioreceptors. For example, initial studies with human IgG antibodies confirm the detection capabilities of the biosensor using electrochemical capacitance spectroscopy. Furthermore, the biosensor can quantify CA-19-9 glycoprotein, a clinical cancer biomarker. The biosensor exhibits a dynamic range from 0 to 300 U mL-1, with a limit of detection of 8.9 U mL-1. Rigorous testing with known concentrations of a pretreated CA-19-9 antigen from human fluids confirmed their accuracy and reliability in detecting the glycoprotein. This study signifies notable progress in capacitive biosensing for clinical biomarkers, potentially leading to more accessible and cost-effective point-of-care solutions.

Glycan-Based Electrochemical Biosensors: Promising Tools for the Detection of Infectious Diseases and Cancer Biomarkers.

Glycan-based electrochemical biosensors are emerging as analytical tools for determining multiple molecular targets relevant to diagnosing infectious diseases and detecting cancer biomarkers. These biosensors allow for the detection of target analytes at ultra-low concentrations, which is mandatory for early disease diagnosis. Nanostructure-decorated platforms have been demonstrated to enhance the analytical performance of electrochemical biosensors. In addition, glycans anchored to electrode platforms as bioreceptors exhibit high specificity toward biomarker detection. Both attributes offer a synergy that allows ultrasensitive detection of molecular targets of clinical interest. In this context, we review recent advances in electrochemical glycobiosensors for detecting infectious diseases and cancer biomarkers focused on colorectal cancer. We also describe general aspects of structural glycobiology, definitions, and classification of electrochemical biosensors and discuss relevant works on electrochemical glycobiosensors in the last ten years. Finally, we summarize the advances in electrochemical glycobiosensors and comment on some challenges and limitations needed to advance toward real clinical applications of these devices.

ß-1,4-Galactosyltransferase-V colorectal cancer biomarker immunosensor with label-free electrochemical detection.

ß-1,4-Galactosyltransferase-V (ß-1,4-GalT-V) is a membrane-bound glycoprotein with glycosyltransferase enzyme activity that synthesizes lactosylceramide and glycosylates high-branched N-glycans in the Golgi apparatus. Colorectal cancer (CRC) tumor cells have shown to overexpress these biomolecules concerning normal cells, releasing them into the body fluids. Thus, their detection has been suggested as a diagnosis/prognosis CRC biomarker. We report the first electrochemical immunosensor for the detection of such a novel ß-1,4-GalT-V CRC biomarker. The label-free electrochemical immunosensor covalently coupled an anti-ß-1,4-GalT-V antibody at a mixed self-assembled monolayer-coated screen-printed gold electrode (SPAuE) surface. This functionalized platform captured the ß-1,4-GalT-V glycoprotein from human serum samples with high specificity, which response monitored by electrochemical impedance spectroscopy (EIS) was protein concentration-dependent. The resultant electrochemical immunosensor showed a linear dynamic range from 5 to 150 pM, with a sensitivity of 14 Ω pM-1 and a limit of detection of 7 pM, of clinical relevance. This outstanding performance makes it great potential for including it in a biomarker signature for the early diagnosis/prognosis of CRC.

Phosphoglycan-sensitized platform for specific detection of anti-glycan IgG and IgM antibodies in serum.

Glycosylphosphatidylinositol anchored proteins (GPI-APs) are natural conjugates in the plasma membrane of eukaryotic cells that result from the attachment of a glycolipid to the C-terminus of many proteins. GPI-APs play a crucial role in cell signaling and adhesion and have implications in health and diseases. GPI-APs and GPIs without protein (free GPIs) are found in abundance on the surface of the protozoan parasite Toxoplasma gondii. The detection of anti-GPI IgG and IgM antibodies allows differentiation between toxoplasmosis patients and healthy individuals using serological assays. However, these methods are limited by their poor efficiency, cross-reactivity and need for sophisticated laboratory equipment and qualified personnel. Here, we established a label-free electrochemical glycobiosensor for the detection of anti-GPI IgG and IgM antibodies in serum from toxoplasmosis seropositive patients. This biosensor uses a synthetic GPI phosphoglycan bioreceptor immobilized on screen-printed gold electrodes through a linear alkane thiol phosphodiester. The antigen-antibody interaction was detected and quantified by electrochemical impedance spectroscopy (EIS). The resultant device showed a linear dynamic range of anti-GPI antibodies in serum ranging from 1.0 to 10.0 IU mL-1, with a limit of detection of 0.31 IU mL-1. This method also holds great potential for the detection of IgG antibodies related to other multiple medical conditions characterized by overexpression of antibodies.

Electrochemical Biosensors for Determination of Colorectal Tumor Biomarkers.

The accurate determination of specific tumor markers associated with cancer with non-invasive or minimally invasive procedures is the most promising approach to improve the long-term survival of cancer patients and fight against the high incidence and mortality of this disease. Quantification of biomarkers at different stages of the disease can lead to an appropriate and instantaneous therapeutic action. In this context, the determination of biomarkers by electrochemical biosensors is at the forefront of cancer diagnosis research because of their unique features such as their versatility, fast response, accurate quantification, and amenability for multiplexing and miniaturization. In this review, after briefly discussing the relevant aspects and current challenges in the determination of colorectal tumor markers, it will critically summarize the development of electrochemical biosensors to date to this aim, highlighting the enormous potential of these devices to be incorporated into the clinical practice. Finally, it will focus on the remaining challenges and opportunities to bring electrochemical biosensors to the point-of-care testing.

Microalgae protoplasts isolation and fusion for biotechnology research / Aislamiento y fusión de protoplastos de microalgas para aplicaciones biotecnológicas

ABSTRACT Protoplasts are microbial or vegetable cells lacking a cell wall. These can be obtained from microalgae by an enzymatic hydrolysis process in the presence of an osmotic stabilizer. In general, protoplasts are experimentally useful in physiological, genetic and biochemical studies, so their acquisition and fusion will continue to be an active research area in modern biotechnology. The fusion of protoplasts in microalgae constitutes a tool for strain improvement because it allows both intra and interspecific genetic recombination, resulting in organisms with new or improved characteristics of industrial interest. In this review we briefly describe the methodology for obtaining protoplasts, as well as fusion methods and the main applications of microalgal platforms.

RESUMEN Los protoplastos son células microbianas o vegetales que carecen de pared celular. Estos pueden obtenerse a partir de microalgas por un proceso de hidrólisis enzimática en presencia de un estabilizador osmótico. En general, los protoplastos son experimentalmente útiles en estudios fisiológicos, genéticos y bioquímicos, por lo que su obtención y fusión continuarán siendo un área de investigación activa en la biotecnología moderna. La fusión de protoplastos en microalgas constituye una herramienta para el mejoramiento de cepas pues permite la recombinación genética intra e interespecífica, logrando así organismos con nuevas características de interés industrial. En esta revisión, describimos brevemente la metodología para obtener protoplastos, métodos de fusión y las principales aplicaciones de las plataformas basadas en microalgas.