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ABSTRACT Magnesium (Mg) is essential for the metabolic reactions of the human body and is known for its biocompatibility, its mechanical and physical properties are similar to human bone, which is why it is considered to have high potential in biomedical applications such as temporary and resorbable implants. Through surface modifications, the high tendency to corrosion of Mg could be controlled, such as biodegradable membranes that prevent the passage of chloride ions present in the human organism. To prepare the membrane, solutions of chitosan modified with gelatin and/or glutaraldehyde are used and by means of the electrospray method applied to protect the Mg. To simulate body fluid conditions a Kokubo saline solution (BFK) was prepared. The study focuses on evaluating the corrosion rate of Mg with a coating made of a chitosan electrosprayed membrane, applying electrochemical measurements of electrochemical impedance spectroscopy and linear polarization resistance. The key additive to improve the behavior of the membranes was observed with the use of gelatin, where the membrane with the best results lowing corrosion rates is the Mg CH+GE+GL system, which it was observed with very good physical integrity in the images of morphological analyzes of the surface after 30 days of exposure.
RESUMEN El magnesio (Mg) es esencial para las reacciones metabólicas del cuerpo humano y es conocido por su biocompatibilidad, sus propiedades mecánicas y físicas son similares a las del hueso humano, por lo que se considera que tiene un alto potencial en aplicaciones biomédicas como implantes temporales y reabsorbibles. Mediante modificaciones superficiales se podría controlar la alta tendencia a la corrosión del Mg, como por ejemplo membranas biodegradables que impidan el paso de iones cloruro presentes en el organismo humano. Para preparar la membrana se utilizan soluciones de quitosano modificado con grenetina y/o glutaraldehído y mediante el método de electrorociado se aplican para proteger el Mg. Para simular las condiciones de los fluidos corporales se preparó una solución salina de Kokubo. El estudio se enfoca en evaluar la velocidad de corrosión del Mg con un recubrimiento hecho de una membrana electrorociada con quitosano, aplicando técnicas electroquímicas de espectroscopia de impedancia electroquímica y resistencia de polarización lineal. El aditivo clave para mejorar el comportamiento de las membranas se observó con el uso de gelatina, donde la membrana con mejores resultados bajando los índices de corrosión es el sistema Mg CH+GR+GL, el cual se observó con muy buena integridad física en las imágenes de análisis morfológicos de la superficie después de 30 días de exposición.
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Abstract The aim of this study was to obtain ionic quantification in periradicular medium after diffusion tests of the solution used inside root canals during the electrochemical dissolution of endodontic file fragments and the NiTi-containing dissolution product via an apical foramen. Thirty single-rooted extracted human teeth had root canals prepared and were attached to Eppendorf tubes filled with sterile saline. The samples were divided into 3 groups (n = 10) according to the solution used inside the root canal during the diffusion tests: Group 1: [NaF 12 g/L + NaCl 1 g/L]; Group 2: [NaF 12 g/L + NaCl 1 g/L + NiTi 0.50 g/L]; Group 3: [NaF 6 g/L + NaCl 0.5 g/L + NiTi 0.25 g/L]. The sample in each Eppendorf tube was then analyzed to assay the ionic quantification in periradicular medium. The groups were compared in relation to ionic quantifications (Kruskal-Wallis and Dunn's tests, p ≤ 0.05). Group 2 showed significantly higher F-, Ni and Ti quantities than groups 1 and 3 (p < 0.05). Group 3 showed significantly higher Ti and Ni quantities than group 1, where no measurable quantities of Ti and Ni were observed (p < 0.05). The conclusions were that a 50% dilution of the NiTi-containing dissolution product resulted in significantly lower F-, Ni and Ti quantities compared to the undiluted product. The quantifications observed here suggest that irrigation is recommendable during the electrochemical dissolution process to reduce the resultant ion concentrations in both the root canal and the periradicular medium.
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Objective@#A label-free electrochemical immunosensor was developed for the detection of nuclear matrix protein-22 (NMP22) as a biomarker of bladder cancer.@*Methods@#The study was based on the establishment and validation of the methodology. Urine samples were collected from 20 patients with bladder cancer and 20 controls in the affiliated Hongqi hospital of Mudanjiang medical university from September in 2017 to July in 2019 to validate the developed method. A screen-printed electrode (SPE) was modified with a film of a composite made from the reduced graphene oxide-tetraethylene pentamine (rGO-TEPA) immobilized Zn-based-Metal-organic frameworks deposited with Au nanoparticles (rGO-TEPA@Au-ZIF8). Primary antibody against NMP22 was immobilized on the Au nanoparticles on the surface of the modified SPE, which then was blocked with bovine serum albumin to elimiate nonspecific binding sites. The process of the construction of the proposed sensorwas characterized by cyclic voltammetry and electrochemical impedance spectroscopy. Differential pulse voltammetry was used to evaluate the linear range, recovery, precision, selectivity and stability. The data were analyzed by Mann-Whitney U test.@*Results@#Under optimal conditions, the immunosensor exhibited a linear range of 0.01-1000 ng/mlwith a detection limit of 3.33 pg/ml (S/N=3) and a standard recovery of 97.65%-107.05%. The levels of NMP22 in urine samples from patients with bladder cancer [66.03 (4.34, 91.74)]ng/ml determined by the proposed sensor were significantly higher than those of controls 0.54(0.06, 8.84) ng/ml(P=0.001).@*Conclusion@#The immunosensor can achieve sensitive, rapid and acucurate detection of NMP22, and has potential application prospects in monitoring tumor markers.
ABSTRACT
Objective A label-free electrochemical immunosensor was developed for the detection of nuclear matrix protein-22 (NMP22) as a biomarker of bladder cancer. Methods The study was based on the establishment and validation of the methodology. Urine samples were collected from 20 patients with bladder cancer and 20 controls in the affiliated Hongqi hospital of Mudanjiang medical university from September in 2017 to July in 2019 to validate the developed method. A screen-printed electrode (SPE) was modified with a film of a composite made from the reduced graphene oxide-tetraethylene pentamine (rGO-TEPA) immobilized Zn-based-Metal-organic frameworks deposited with Au nanoparticles (rGO-TEPA@Au-ZIF8). Primary antibody against NMP22 was immobilized on the Au nanoparticles on the surface of the modified SPE, which then was blocked with bovine serum albumin to elimiate nonspecific binding sites. The process of the construction of the proposed sensorwas characterized by cyclic voltammetry and electrochemical impedance spectroscopy. Differential pulse voltammetry was used to evaluate the linear range, recovery, precision, selectivity and stability. The data were analyzed by Mann-Whitney U test. Results Under optimal conditions, the immunosensor exhibited a linear range of 0.01-1000 ng/mlwith a detection limit of 3.33 pg/ml (S/N=3) and a standard recovery of 97.65％-107.05％. The levels of NMP22 in urine samples from patients with bladder cancer [66.03 (4.34, 91.74)]ng/ml determined by the proposed sensor were significantly higher than those of controls 0.54(0.06, 8.84) ng/ml(P=0.001). Conclusion The immunosensor can achieve sensitive, rapid and acucurate detection of NMP22, and has potential application prospects in monitoring tumor markers.
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Vitamin is one of the essential nutrients of human body.Monitoring the level of the vitamin receives more and more attention clinically.Common ways of vitamin detection include microbiological method, fluorescence analysis, immunological method, high performance liquid chromatography,liquid chromatography-mass spectrometry,electrochemical method and so on.In addition, there′re still many disputes on the reference interval of vitamins,the medical decision level and the specific reference intervals for different groups.Therefore,establishing a standardized method of vitamin detection is an urgent problem to be solved.
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Electrochemical immunosensors is widely used in clinical laboratory diagnosis for its unique properties such as cost-effective, rapid, sensitive and specific and play a role in POCT and rapid diagnosis.This paper introduces the principle and advantages of electrochemical immunosensor.Biological molecules such as tumor marker, myocardial marker, hormone, pathogenic bacteria, viruses, and autoimmune antibody has carried on the induction,based on the domestic and foreign research results.The advantages and disadvantages of electrochemical immunosensor was evaluated, and the research on its application prospect is analyzed.
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BACKGROUND: Self-monitoring of blood glucose plays an important role in management of diabetes mellitus. Blood glucose measurement is based on using plasma glucose separated from whole blood, but many people with diabetes and health care providers use a portable glucose meter for convenience. The aim of this study was to evaluate the accuracy and agreement of G300 portable glucose monitoring system against standard venous glucose testing methods, based on ISO 15197:2013 standards. METHODS: This study was the evaluation of G300 system accuracy following ISO 15197:2013 standards. We estimated precision, system accuracy, hematocrit interference, interfering substances, and user performance. RESULTS: In repeatability precision evaluation of those glucometers, standard deviation was 2.9–3.7 mg/dL at glucose levels under 100 mg/dL and coefficient of variation was 1.7–3.2% at glucose levels over 100 mg/dL, respectively. In accuracy evaluation, 99.5% of difference values between results of G300 portable glucose monitoring system and clinical laboratory were within 95%. Consensus Error grid analysis showed that all values (100%) are within zone A. Hematocrit range between 20% and 60% did not cause interference. These results were acceptable for the ISO15197:2013 criteria in all glucose concentrations. CONCLUSIONS: This study showed that G300 can provide reliable blood glucose results for patients and health care providers to manage diabetes mellitus, satisfying the ISO 15197:2013 criteria.
Subject(s)
Humans , Blood Glucose Self-Monitoring , Blood Glucose , Capillaries , Consensus , Diabetes Mellitus , Electrochemical Techniques , Fasting , Glucose , Health Personnel , HematocritABSTRACT
ABSTRACT Introduction: nickel-titanium (nitinol) wires may potentially corrode oral environments causing biocompatibility problems. The purpose of this study was to compare the behavior of corrosion of nitinol wires in artificial saliva with different levels of pH, fluoride concentration, and tension degrees. Methods: an experimental study applying four electrochemical techniques: corrosion potential, linear polarization resistance, Tafel curves, and electrochemical impedance spectroscopy. Samples were cemented on teeth simulating different crowding degrees (56 gf and 224 gf) at various levels of fluoride concentration (0% and 0.5%) and pH (4 and 7). Results: the corrosion strength values for a sample submerged at pH 4, 0% NaF during 5 hours is lower for a force of 224 gf than for 56 gf. When the electrolyte is added a concentration of 0.5% sodium fluoride, it increases polarization resistance for a force of 224 gf. Conclusion: this study confirmed the existence of oxides on the nickel-titanium surface, especially on the arch exposed for 14 days to pH 4 and 0.5% NaF.
RESUMEN Introducción: los alambres de níquel-titanio (nitinol) poseen potencial de corrosión en el medio bucal y pueden ocasionar problemas de biocompatibilidad. El propósito de este estudio fue comparar el comportamiento de corrosión que presentan los alambres de nitinol en saliva artificial con diferentes niveles de pH, concentración de fluoruros y grados de tensión. Métodos: se desarrolló un estudio de tipo experimental, aplicando cuatro técnicas electroquímicas: potencial de corrosión, resistencia a la polarización lineal, curvas de Tafel y espectroscopía de impedancia electroquímica. Los especímenes fueron cementados en dientes que simulaban diferentes grados de apiñamiento (56 gf y 224 gf), a diversos niveles de concentración de fluoruros (0% y 0,5%) y pH (4 y 7). Resultados: se observó que el valor de resistencia a la corrosión para una muestra sumergida a pH 4, 0% NaF y a 5 horas de inmersión es menor para la fuerza de 224 gf que para la de 56 gf. Cuando se le agrega al electrolito la concentración de fluoruro de sodio de 0,5%, aumenta la resistencia a la polarización para una fuerza equivalente de 224 gf. Conclusiones: se confirmó la existencia de óxidos sobre la superficie del níquel-titanio, especialmente en el arco expuesto durante 14 días a pH 4 y 0,5% en peso de NaF.
Subject(s)
Fluorosis, Dental , Electrochemical Techniques , FluoridesABSTRACT
OBJECTIVES: This paper suggests the experimental guidelines to evaluate the electro-mechanical safety of belt type equipment. The electro-mechanical safety was determined by using the International Electrotechnical Commission guidelines, which are widely used as important factors for assessing the electro-mechanical safety of belt type equipment. However, the local guidelines on wearable healthcare sensors are currently not well-established. Therefore, safety guidelines suited for the actual circumstances in Korea are required, and this paper attempts to try a new experimental safety test procedure of the wearable healthcare sensor. METHODS: This belt type device measures the electrocardiogram (ECG) and heart rates by attaching to the chest. Examination lists were selected by analyzing the common standards ofelectro-mechanical safety (IEC 60601-1) and environment tests (IEC 60068-1, IEC 60068-2) of home-healthcare equipment. RESULTS: The essential electrical safety, which was required for the RS300G3 as a medical device, was evaluated, and most of the examination lists were selected by considering the circumstances of the users. The device passed all the selected examinable lists that are applicable to the Korean environment. CONCLUSIONS: This study has limitations to estimate and to conduct electro-mechanical safety experiments because our study focused on the belt type of heart-rates equipment. We are not taking into account the overall electro-mechanical home-healthcare measurements. According to industrial and technological development, there are infinite possibilities for the advancement of home-healthcare equipment, so more examination lists for safety are being added in addition to what we have done.