Micromotor-based electrochemical immunoassays for reliable determination of amyloid-ß (1-42) in Alzheimer's diagnosed clinical samples.

Alzheimer's disease (AD), in addition to being the most common cause of dementia, is very difficult to diagnose, with the 42-amino acid form of Aß (Aß-42) being one of the main biomarkers used for this purpose. Despite the enormous efforts made in recent years, the technologies available to determine Aß-42 in human samples require sophisticated instrumentation, present high complexity, are sample and time-consuming, and are costly, highlighting the urgent need not only to develop new tools to overcome these limitations but to provide an early detection and treatment window for AD, which is a top-challenge. In recent years, micromotor (MM) technology has proven to add a new dimension to clinical biosensing, enabling ultrasensitive detections in short times and microscale environments. To this end, here an electrochemical immunoassay based on polypyrrole (PPy)/nickel (Ni)/platinum nanoparticles (PtNPs) MM is proposed in a pioneering manner for the determination of Aß-42 in left prefrontal cortex brain tissue, cerebrospinal fluid, and plasma samples from patients with AD. MM combines the high binding capacity of their immunorecognition external layer with self-propulsion through the catalytic generation of oxygen bubbles in the internal layer due to decomposition of hydrogen peroxide as fuel, allowing rapid bio-detection (15 min) of Aß-42 with excellent selectivity and sensitivity (LOD = 0.06 ng/mL). The application of this disruptive technology to the analysis of just 25 µL of the three types of clinical samples provides values concordant with the clinical values reported, thus confirming the potential of the MM approach to assist in the reliable, simple, fast, and affordable diagnosis of AD by determining Aß-42.

Evaluation of pathogen disinfection efficiency of electrochemical advanced oxidation to become a sustainable technology for water reuse.

Water treatment and reuse is gaining acceptance as a strategy to fight against water contamination and scarcity, but it usually requires complex treatments to ensure safety. Consequently, the electrochemical advanced processes have emerged as an effective alternative for water remediation. The main objective here is to perform a systematic study that quantifies the efficiency of a laboratory-scale electrochemical system to inactivate bacteria, bacterial spores, protozoa, bacteriophages and viruses in synthetic water, as well as in urban wastewater once treated in a wetland for reuse in irrigation. A Ti|RuO2-based plate and Si|BDD thin-film were comparatively employed as the anode, which was combined with a stainless-steel cathode in an undivided cell operating at 12 V. Despite the low resulting current density (<15 mA/cm2), both anodes demonstrated the production of oxidants in wetland effluent water. The disinfection efficiency was high for the bacteriophage MS2 (T99 in less than 7.1 min) and bacteria (T99 in about 30 min as maximum), but limited for CBV5 and TuV, spores and amoebas (T99 in more than 300 min). MS2 presented a rapid exponential inactivation regardless of the anode and bacteria showed similar sigmoidal curves, whereas human viruses, spores and amoebas resulted in linear profiles. Due the different sensitivity of microorganisms, different models must be considered to predict their inactivation kinetics. On this basis, it can be concluded that evaluating the viral inactivation from inactivation profiles determined for bacteria or some bacteriophages may be misleading. Therefore, neither bacteria nor bacteriophages are suitable models for the disinfection of water containing enteric viruses. The electrochemical treatment added as a final disinfection step enhances the inactivation of microorganisms, which could contribute to safe water reuse for irrigation. Considering the calculated low energy consumption, decentralized water treatment units powered by photovoltaic modules might be a near reality.

Binary MoS2 nanostructures as nanocarriers for amplification in multiplexed electrochemical immunosensing: simultaneous determination of B cell activation factor and proliferation-induced signal immunity-related cytokines.

A dual immunosensor is reported for the simultaneous determination of two important immunity-related cytokines: BAFF (B cell activation factor) and APRIL (a proliferation-induced signal). Sandwich-type immunoassays with specific antibodies (cAbs) and a strategy for signal amplification based on labelling the detection antibodies (dAbs) with binary MoS2/MWCNTs nanostructures and using horseradish peroxidase (HRP) were implemented. Amperometric detection was carried out at screen-printed dual carbon electrodes (SPdCEs) through the hydroquinone HQ/H2O2 system. The developed dual immunosensor provided limit of detection (LOD) of 0.08 and 0.06 ng mL-1 for BAFF and APRIL, respectively, and proved to be useful for the determination of both cytokines in cancer cell lysates and serum samples from patients diagnosed with autoimmune diseases and cancer. The obtained results agreed with those found using ELISA methodologies.

A combined analytical-chemometric approach for the in vitro determination of polyphenol bioaccessibility by simulated gastrointestinal digestion.

In this study, an integrated characterisation through polyphenol and caffeine content and antioxidant activity was combined with chemometric analysis to assess the effects of simulated in vitro gastrointestinal digestion on the bioaccessibility of these bioactive compounds from nine different tea infusions. Tea infusions were characterised based on total flavonoids, total polyphenols and antioxidant activity, together with the determination of individual polyphenol content. Fourteen phenolic compounds, including phenolic acids, stilbenes and flavonoids, were selected based on their reported bioactivity and high accessibility, attributed to their low molecular weight. Both polyphenols and caffeine were initially monitored in raw tea infusions and through the different digestion stages (salivary, gastric and duodenal) by capillary high performance liquid chromatography coupled to diode array detection (cHPLC-DAD) and/or HPLC coupled to a triple quadrupole mass analyser (HPLC-MS/MS). Multivariate analysis of the studied bioactives, using principal component analysis and cluster analysis, revealed that the decaffeination process seems to increase the stability and concentration of the compounds evaluated during digestion. The greatest transformations occurred mainly in the gastric and duodenal stages, where low bioactivity indices (IVBA) were shown for resveratrol and caffeic acid (IVBA = 0%). In contrast, the polyphenols gallic acid, chlorogenic acid and quercetin gave rise to their availability in white, green and oolong infusion teas (IVBA > 90%). Furthermore, highly fermented black and pu-erh varieties could be designated as less bioaccessible environments in the duodenum with respect to the tested compounds.

Unraveling autoimmune and neurodegenerative diseases by amperometric serological detection of antibodies against aquaporin-4.

This work reports the first electroanalytical bioplatform to date for the determination of antibodies against aquaporin-4 (AQP4-Abs), whose serum level is considered as relevant biomarker for certain autoimmune diseases. The bioplatform relies on the use of magnetic microparticles modified with the biotinylated protein for the capture of specific antibodies. The captured IgGs are enzymatically labelled with a secondary antibody conjugated to the horseradish peroxidase (HRP) enzyme. Amperometric transduction is performed using the H2O2/hydroquinone (HQ) system, which results in a cathodic current variation directly proportional to the concentration of the target antibodies. The evaluation of the analytical and operational characteristics of the developed bioplatform shows that it is competitive in terms of sensitivity with the only biosensor reported to date as well as with the commercially available ELISA kits. The achieved limit of detection value is 8.8 pg mL-1. In addition, compared to ELISA kits, the developed bioplatform is advantageous in terms of cost and point of care operation ability. The bioplatform was applied to the analysis of control serum samples with known AQP4-Abs contents as well as of sera from healthy individuals and patients diagnosed with Systemic Lupus Erythematosus (SLE) and Alzheimer (AD) diseases, providing results in agreement with the ELISA methodology.

Electrochemical immunoplatform to assist in the diagnosis and classification of breast cancer through the determination of matrix-metalloproteinase-9.

Matrix metalloproteinase 9 (MMP-9) is a zinc-dependent endopeptidase that promotes angiogenesis, tumor growth, metastasis and cell invasion through the degradation of extracellular matrix. This work reports a magnetic microbeads (MBs)-based sandwich immunoassay for the amperometric determination of MMP-9 at screen-printed carbon electrodes (SPCEs). The suitable capture antibody (cAb) is immobilized onto carboxylic MBs to selectively capture the antigen which is sandwiched with a biotinylated detector antibody (biotin-dAb) further conjugated with a commercial streptavidin-horseradish peroxidase (Strep-HRP) polymer. This immunoplatform provides great analytical characteristics in terms of selectivity and sensitivity, achieving a LOD value of 2.4 pg mL-1 for standards in buffered solutions. Although this value is similar to those reported for some other approaches described so far, the method described here is simpler involving a single 30 min incubation step which makes it ideal for automation or implementation in POC devices. Moreover, the method was assayed for the accurate determination of endogenous MMP-9 in both cancer cell lysates and serum samples of patients diagnosed with different subtypes of breast cancer (BC) after a simple dilution. The results obtained show that the disposable and affordable immunoplatform developed is able not only to discriminate BC patients from healthy individuals but also to do it for the worst outcome triple negative (TNBC) subtype.

Simultaneous amperometric immunosensing of the metastasis-related biomarkers IL-13Rα2 and CDH-17 by using grafted screen-printed electrodes and a composite prepared from quantum dots and carbon nanotubes for signal amplification.

This paper describes a dual electrochemical immunoassay for the simultaneous determination of IL-13Rα2 and CDH-17, two biomarkers of emerging relevance in metastatic processes. The sandwich assay uses a screen-printed dual carbon electrode that was electrochemically grafted with p-aminobenzoic acid to allow the covalent immobilization of capture antibodies. A hybrid composed of graphene quantum dots (GQDs) and multiwalled carbon nanotubes (MWCNTs) act as nanocarriers for the detection antibodies and horseradish peroxidase. The use of this hybrid material considerably improves the assay (in comparison to the use of MWCNTs) due to the peroxidase mimicking activity of the GQDs. The method works at a low working potential (0.20 V vs. Ag pseudo-reference electrode) and thus is not readily interfered by unknown electroactive species. The dual immunoassay allows for the selective determination of both biomarkers with LOD values of 1.4 (IL-13sRα2) and 0.03 ng mL-1 (CDH-17). The simultaneous determination of IL-13Rα2 and CDH-17 was accomplished in lysates from breast and colorectal cancer cells with different metastatic potential, and in paraffin-embedded tumor tissues extracts from patients diagnosed with colorectal cancer at different stages. The applicability to discriminate the metastatic potential even in intact cells through the detection of both extracellular receptors has been demonstrated also. The assay can be performed within 3 h, requires small sample amounts (0.5 µg), and has a simple protocol. Graphical abstract Dual amperometric immunosensing of the metastasis-related biomarkers IL-13Rα2 and CDH-17 in human colorectal cancer cells and tissues by using grafted screen-printed electrodes and composites of quantum dots and carbon nanotubes as nanocarriers.

Versatile Electroanalytical Bioplatforms for Simultaneous Determination of Cancer-Related DNA 5-Methyl- and 5-Hydroxymethyl-Cytosines at Global and Gene-Specific Levels in Human Serum and Tissues.

This paper reports the preparation of versatile electrochemical biosensing platforms for the simple, rapid, and PCR-independent detection of the most frequent DNA methylation marks (5-methylcytosine, 5-mC, and/or 5-hydroxymethylcytosine, 5-hmC) both at global and gene-specific levels. The implemented strategies, relying on the smart coupling of immuno-magnetic beads (MBs), specific DNA probes and amperometric detection at screen-printed carbon electrodes (SPCEs), provided sensitive and selective determination of the target methylated DNAs in less than 90 min with a great reproducibility and demonstrated feasibility for the simultaneous detection of the same or different cytosine epimarks both at global level and in different loci of the same gene or in different genes. The bioplatforms were applied to determine global methylation events in paraffin-embedded colorectal tissues and specific methylation at promoters of tumor suppressor genes in genomic DNA extracted from cancer cells and paraffin-embedded colorectal tissues, and in serum without previous DNA extraction from cancer patients.

Determination of Cadherin-17 in Tumor Tissues of Different Metastatic Grade Using a Single Incubation-Step Amperometric Immunosensor.

This paper reports the development of an amperometric immunosensing platform for the determination of cadherin-17 (CDH-17), an atypical adhesion protein involved in the progression, metastatic potential, and survival of high prevalence gastric, hepatocellular, and colorectal tumors. The methodology developed relies on the efficient capture and enzymatic labeling of the target protein on the magnetic microparticles (MBs) surface using commercial antibodies and amperometric transduction at screen-printed carbon electrodes (SCPEs) through the HRP/H2O2/HQ system. The developed immunosensing platform allows the selective determination of the target protein at low ng mL-1 level (LOD of 1.43 ng mL-1) in 45 min and using a single incubation step. The electrochemical immunosensor was successfully used for the accurate determination of the target protein in a small amount (0.5 µg) of raw lysates of colon cancer cells with different metastatic potential as well as in extracts from paraffin embedded cancer colon tissues of different metastatic grade.

Electrochemical immunosensor for IL-13 Receptor α2 determination and discrimination of metastatic colon cancer cells.

This work describes the first electrochemical immunosensor reported for the determination of IL-13 receptor Rα2 (IL-13Rα2), an emerging relevant biomarker in metastatic colon cancer. The approach involves the formation of sandwich immunocomplexes using specific capture (CAb) and biotinylated detector antibodies (BDAb) further labeled with an streptavidin-horseradish peroxidase (Strep-HRP) polymer, onto carboxylic acid-modified magnetic microbeads (HOOC-MBs). Amperometric detection at disposable carbon screen-printed electrodes (SPCEs) using the (H2O2)/hydroquinone (HQ) system was employed to monitor the affinity reactions. The developed immunosensor exhibits a linear calibration plot over the 3.9-100 ng mL-1 concentration range, a LOD of 1.2 ng mL-1 and excellent selectivity against other non-target proteins. The amperometric immunosensor was applied successfully to quantify for the first time the IL-13Rα2 expression in raw lysates of colon cancer cells and to discriminate the metastatic potential of intact cells through recognition of this target extracellular receptor. In comparison with the commercial Enzyme-Linked ImmunoSorbent Assay (ELISA) kit involving the same immunoreagents, the immunosensor provides a similar LOD in a half-time for the assay.

Rapid Electrochemical Assessment of Tumor Suppressor Gene Methylations in Raw Human Serum and Tumor Cells and Tissues Using Immunomagnetic Beads and Selective DNA Hybridization.

We report a rapid and sensitive electrochemical strategy for the detection of gene-specific 5-methylcytosine DNA methylation. Magnetic beads (MBs) modified with an antibody for 5-methylcytosines (5-mC) are used for the capture of any 5-mC methylated single-stranded (ss)DNA sequence. A flanking region next to the 5-mCs of the captured methylated ssDNA is recognized by hybridization with a synthetic biotinylated DNA sequence. Amperometric transduction at disposable screen-printed carbon electrodes (SPCEs) is employed. The developed biosensor has a dynamic range from 3.9 to 500 pm and a limit of detection of 1.2 pm for the methylated synthetic sequence of the tumor suppressor gene O-6-methylguanine-DNA methyltransferase (MGMT) promoter region. The method is applied in the 45-min analysis of specific methylation in the MGMT promoter region directly in raw spiked human serum samples and in genomic DNA extracted from U-87 glioblastoma cells and paraffin-embedded brain tumor tissues without any amplification and pretreatment step.

Experiencia de la consulta homeopática de un programa docente en Costa Rica, 2003-2007. Un enfoque de atención holística / Experience of a Homeopathy Consultation at a Teaching Program in Costa Rica, from 2003 to 2007

Objetivos: Describir la experiencia de la consulta homeopática, su metodología y caracterizar a los pacientes. Material y métodos: Estudio descriptivo de 83 expedientes; se analizaron variables cualitativas (sexo, estado conyugal, ocupación, escolaridad, residencia, credo, modo de acceso a la consulta, motivo de consulta, motivos de consulta físicos y psíquicos, dolor, síntomas psíquicos y físicos, diagnóstico o problemas) y cuantitativas (edad, duración de la primera consulta, número de motivos de consulta, número de diagnósticos /problemas principales, comparación del número de motivos de consulta con los diagnósticos /problemas, número total de consultas, número y costo de los medicamentos y resultado de la aplicación de la Glasgow Homoeopathic Hospital Outcome Scale. La información se recolectó del expediente clínico. Los datos se almacenaron y analizaron en el programa SPPS versión 12.0; se obtuvieron medidas de tendencia central, frecuencias y proporciones. Resultados: Se atendieron 83 personas, con un intervalo de edad entre 5 meses y 83 años, promedio 38 años. 79% adultos, predominó el sexo femenino. 57% accedió por demanda libre; 28% por referencia de médicos y enfermeros. 81% consultó por problemas físicos de salud; una vez realizado el diagnóstico, la proporción de estos disminuyó casi a la mitad y los físico-psíquicos se incrementaron ocho veces. El promedio de duración de la primera consulta fue de 66 minutos, del número de consultas fue de dos y el de medicamentos, de tres. El costo promedio de las prescripciones fue de ¢1.946ºº por paciente. Conclusiones: En el distrito de Pavas existe demanda por la consulta homeopática, que debe investigarse. Este enfoque terapéutico holístico identificó trastornos de salud no reportados por los pacientes como motivos de consulta iniciales. Los resultados obtenidos coinciden, en algunos aspectos, con otras investigaciones internacionales en el campo de la práctica clínica homeopática.

Objectives: To describe the experience, clinical methods and patients characteristics seen during homeopathic consultation. Methods: The present is a descriptive study of 83 total clinical records. The following qualitative variables were analyzed (sex, marriage status, occupation, education, residence, religion, referral manner, physical an psychic consultation reasons, diagnosis or problems). Quantitative variables were: age, duration of first consultation, number of complaints at consultation, comparison between number of complaints for consultation with diagnosis / problems, total number of consultations, number and cost of homeopathic medications and results of the application of the Glasgow Homoeopathic Hospital Outcome Scale. Data was obtained from the clinical records, and then analyzed with the SPPS software 12.0 version. Central tendency measures, frequencies and proportions were obtained. Results: 83 patients were seen, during the study period, ranging from 5 months to 83 years of age, average 38 years. There was female sex majority, and 79% were adult. Fifty seven percent attended on their own will, 28% were referred by physicians or nurses. Eighty one percent consulted because of physical problems, however after establishing a medical diagnosis, those diminished around 50% but psycho-physical health problems increased 8 times. The average of the first consultation was 66 minutes; the number of consultations was 2 and 3 the medications per person. The average cost of the prescriptions was ¢ 1 946.00 (aprox. 3 US dollars) per patient. Conclusions: There is a demand for homeopathic consultation in Pavas district that should be investigated. The holistic therapeutic approach identified health problems in patients, that they did not report at the initial consultation. The results obtained coincidence in some aspects, with other international investigations in the field of clinical homeopathic practice.

Homeopatía y curriculum de medicina / Homeopathy and medicine curriculum

El racionalismo-mecanisismo, es el fundamento filosófico de la biología experimental, en la que se basa la terapéutica de la medicina moderna. Esta filosofía condicionó en el pasado, que el desarrollo del curriculum de medicina careciera de otros enfoques terapéuticos como la homeopatía. Los avances en la investigación, la globalización del conocimiento y la búsqueda de enfoques terapéuticos más comprensivos, muestran una apertura de las escuelas de medicina, hacia la complementación médica en terapéuticas no incluidas aún en los currículos de medicina

Medicina homeopática en Costa Rica / Homeopathic medicine in Costa Rica

La medicina homeopática está legalizada en Costa Rica desde 1921. Su ejercicio es regulado por el Colegio de Médicos y Cirujanos. El término homeopatía fue acuñado por el médico alemán Samuel Hahnemann. Es una modalidad de tratamiento medicamentoso que se basea en la ley de las semejanzas. Cada afección es tratada con la sustancia que causa una sintomatología parecida. En Costa Rica la homeopatía fue introducida en 1980 por Bartolomé Marichal, un abogado colombiano. El primer médico homeópata costarricense fue el Dr. Gregorio G. Quesada, quien en 1898 se graduó en el Hahnemann Medical College de Chicago. En 1921, el Congreso de la República emitió la ley que autoriza el libre ejercicio de la profesión a "los osteópatas y homeópatas existentes en Costa Rica al tiempo de la promulgación de esta ley con título universitario". En 1929 se fundó la Liga Homeopática de Costa Rica presidida por un ingeniero agrónomo e integrada por un grupo heterogéno. En 1934 regresó al país el Dr. Raúl Villalón Montero, graduado del Consejo Homeopático de Colombia. El virtud de un tratado vigente entre ambos países ejerce la medicina homeopática. Debido a que no se incorporó al colegio de médios, este le suguió una causa por ejercicio ilegal de la medicina durante treinta y cuatro años. En la segundo mitad del presente siglo se han incorporado por examen al Colegio de Médicos dos graduados en escuelas de medicina homeopáticas extranjeras y se ha aceptado como especialista a un egresado de nuestra universidad que siguiera posgrado en México. Otro médico cirujano que realizara igual posgrado ha logrado el reconocimiento de tales estudios en la Universidad de Costa Rica. Se hace una descripción pormenorizada de eventos relacionados con la homeopatía que han sucedido en Costa Rica en los últimos cien años. Se destacan las diversas interpretaciones que ha merecido la legislación que regula su ejercicio en nuestro país, y a pesar de lo cual se ha desarrollado la homeopatía como alternativa terapéutica. Palabras clave: Homeopatía, historia, legislación en Costa Rica, perspectivas.(AU)

Medicina homeopática en Costa Rica / Homeopathic medicine in Costa Rica

La medicina homeopática está legalizada en Costa Rica desde 1921. Su ejercicio es regulado por el Colegio de Médicos y Cirujanos. El término homeopatía fue acuñado por el médico alemán Samuel Hahnemann. Es una modalidad de tratamiento medicamentoso que se basea en la ley de las semejanzas. Cada afección es tratada con la sustancia que causa una sintomatología parecida. En Costa Rica la homeopatía fue introducida en 1980 por Bartolomé Marichal, un abogado colombiano. El primer médico homeópata costarricense fue el Dr. Gregorio G. Quesada, quien en 1898 se graduó en el Hahnemann Medical College de Chicago. En 1921, el Congreso de la República emitió la ley que autoriza el libre ejercicio de la profesión a "los osteópatas y homeópatas existentes en Costa Rica al tiempo de la promulgación de esta ley con título universitario". En 1929 se fundó la Liga Homeopática de Costa Rica presidida por un ingeniero agrónomo e integrada por un grupo heterogéno. En 1934 regresó al país el Dr. Raúl Villalón Montero, graduado del Consejo Homeopático de Colombia. El virtud de un tratado vigente entre ambos países ejerce la medicina homeopática. Debido a que no se incorporó al colegio de médios, este le suguió una causa por ejercicio ilegal de la medicina durante treinta y cuatro años. En la segundo mitad del presente siglo se han incorporado por examen al Colegio de Médicos dos graduados en escuelas de medicina homeopáticas extranjeras y se ha aceptado como especialista a un egresado de nuestra universidad que siguiera posgrado en México. Otro médico cirujano que realizara igual posgrado ha logrado el reconocimiento de tales estudios en la Universidad de Costa Rica. Se hace una descripción pormenorizada de eventos relacionados con la homeopatía que han sucedido en Costa Rica en los últimos cien años. Se destacan las diversas interpretaciones que ha merecido la legislación que regula su ejercicio en nuestro país, y a pesar de lo cual se ha desarrollado la homeopatía como alternativa terapéutica. Palabras clave: Homeopatía, historia, legislación en Costa Rica, perspectivas.