SELF-ASSEMBLED MULTILAYERS OF WATER GLUCOSE MODIFIED-CHITOSAN AND GLUCOSE OXIDASE FOR DETECTION OF GLUCOSE IN MILK SAMPLES
Background: A crucial aspect of electrochemical enzymatic biosensor development is the immobilization of the enzymes, as it directly influences the sensitivity of the bioelectrode. Among the different methods used to incorporate enzymes on the surface of the transducers, layer-by-layer (LbL) self-assembly based on electrostatic interaction with polyelectrolytes of opposite charge stands out due to its simplicity and reproducibility. Aims: The aim of the work was to develop an electrochemical glucose biosensor by LbL assembly of a new functionalized chitosan polycation and the enzyme glucose oxidase (GOx). Methods: Chitosan was chemically functionalized with glucose by the Maillard reaction. The resulting polycation, named G-Chit, is soluble in the medium compatible with the enzyme. The bioelectrode was obtained by alternating adsorption of G-Chit and GOx onto carbon paste electrodes. By selecting the number of bilayer of G-Chit/GOX, the enzyme concentration, and the pH, the electroanalytical performance of the biosensor was optimized. The electrochemical responses were characterized by cyclic voltammetry and chronoamperometry. Results: Under optimized experimental conditions, the biosensor exhibited a sensitivity of (0.81 ± 0.03) µA mM-1 in a glucose concentration range of (0.18 to 1.75) mM. Discussion: Results indicated that catalytic response increases both with the number of G-Chit/GOx bilayers and the enzyme concentration, obtaining the best responses for 3 bilayers and 2 mg mL-1, respectively, while the optimum working pH value was 7.0. Conclusions: The analytical response of the biosensor was tested in milk samples with negligible matrix effects, suggesting a potential application in other dairy products. Results show that G-Chit appears promising for the immobilization of enzymes.
Read ArticleEXTRACTION AND CHARACTERIZATION OF CURCUMIN FROM TURMERIC RHIZOMES GROWN IN MÉRIDA, VENEZUELA
The extraction of naturally occurring compounds is one of the fastest-growing industries because of its benefits against its synthetic analogs. Environmental protection must require the use of natural products instead of chemicals to minimize pollution. Thus, this investigation studies the use of some natural product, as curcumin, as naturally occurring acid‐base indicators. Curcumin can be used as acid-base indicators since it was found that it possesses pH-dependent solubility. Curcumin, the major active component of turmeric, Curcuma longa (Zingiberaceae), is used as a spice in curry and as a coloring agent in yellow mustards, cosmetics, pharmaceuticals, and hair dyes. In this research, the main compound colored rhizome of turmeric (Curcuma longa) cultivated in Mérida, Venezuela, is extracted: Curcumin (C21H20O6) (1E,6E)-1,7-bis(4-hydroxy-3-methoxyphenyl)-1,6-heptadiene-3,5-dione, in a yield of 3.42% after 8 hours of extraction using soxhlet extractor system with organic solvents (hexane and ethanol). The thin-layer chromatography and column performed separation and purification using a mobile phase, a mixture of chloroform-hexane 3:2. The dye was characterized by spectroscopic analysis of visible ultraviolet (UV-Vis) and infrared (IR), in addition to his studio in steering sensitivity as an acid-base indicator. This dye is useful as an acid-base indicator in strong acid-strong base volumes and did not require large amounts of it as it has high sensitivity. The results indicate that curcumin as an acid-base indicator allows the development of new standards in different chemistry fields that require this type of analysis.
Read ArticleSURVEY ON KNOWLEDGE OF SEXUALLY TRANSMITTED INFECTIONS AND GONORRHEA: DO WE KNOW ENOUGH?
Background: Sexually Transmitted Infections (STIs) constitute an important group of infections with serious implications for public health. According to WHO, 1 million new contagions are produced daily, with more than 370 million new cases yearly. STIs can be originated from viruses, bacteria, fungi, or parasites. Regardless of their nature, they can be either cured or treated and controlled, but more importantly, they are preventable. Aims: The best tool to fight against STIs is prevention, which has a strong dependence on knowledge. This work aimed to assess the level of knowledge of society about STIs and gonorrhea. Methods: We conducted an online survey, covering a wide range of ages and levels of education, inquiring about areas such as origin, ways of contagion, prevention, associated diseases, and treatment of STIs and gonorrhea. We performed a statistical analysis of the answers. Results and Discussion: it was found that the general level of knowledge about STIs was independent of the age and level of education of the respondents. The respondent has shown better familiarity with prevention and contagion than with origin, diseases, and treatment. When the question was focused on gonorrhea, we found a lack in the cognizance of several points. Conclusions: Based on our findings, we conclude it is necessary to improve sexual education programs, starting at early ages but directed to all populations, particularly about gonorrhea.
Read Article