SOUTHERN JOURNAL OF SCIENCES

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.

Background: This interview covers Dr. Peter McCullough’s medical career, experience as an editor of medical journals, and his expertise in areas such as cardiomyopathy, myocarditis, and pericarditis. Aims: The primary aim is to understand Dr. McCullough’s perspectives on various medical topics, including his journey as a cardiologist, the importance of peer review, the phenomenon of Pheidippides cardiomyopathy, the differences between myocarditis and pericarditis, and the significance of ethical principles like the Nuremberg Code and the Declaration of Helsinki. Additionally, the interview aims to explore his concerns about censorship during the COVID-19 pandemic. Methods: The interview follows a question-and-answer format, with the interviewer posing questions to Dr. McCullough on various topics related to his medical career, research interests, and ethical considerations. Results: Dr. McCullough shares his insights on topics such as cardiomyopathy, myocarditis, and pericarditis, emphasizing the importance of peer review, identifying potential biases, and balancing scientific rigor with timely dissemination of findings. He also highlights the significance of the Nuremberg Code and the Declaration of Helsinki in ensuring informed consent and preventing coercion in medical research and treatment. Discussion: Dr. McCullough expresses concerns about censorship during the COVID-19 pandemic, which he believes impacted the ability of medical professionals to freely discuss and disseminate health-related information. He also discusses the potential role of COVID-19 vaccines in causing myocarditis and the need for transparent communication about treatment options and potential complications. Conclusion: The interview provides valuable insights from Dr. McCullough’s extensive medical experience and expertise, covering a range of topics from cardiovascular conditions to ethical principles and the challenges posed by censorship during the COVID-19 pandemic.

Background: Infectious diseases are a global problem, the second human cause of death. Infectious diseases caused by pathogenic bacteria have been treated with a high degree of efficacy. However, even when the 20th century was considered the “golden age” of antibiotics, bacteria developed a different resistance mechanism to antibiotics. In 2017, the WHO issued an alert about 12 bacteria with an urgent need to develop new antibiotics. Aims: The aim of the present review is to analyze the current knowledge of the antibacterial activity of natural extract-based treatments against the pathogens listed by WHO. Methods: A systematic review of the literature in PubMed was performed to search for publications describing the use of natural extracts as antibiotics over bacteria. We focused on the Gram-Negative group. The exclusion criteria consisted of limiting papers on natural extracts tested over the bacteria culture related to eight selected bacteria, according to an alert issued by WHO in 2017, and seven plant extracts. Results: All the Gram-Negative bacteria listed in 2017 by WHO have been treated, with different degrees of advance, with some of the plant extracts and plant-based compounds reviewed. In general, the first approach is using inhibition disks applied over the bacterial biofilm in solid culture media. Discussion: While Salmonellae and P. aeruginosa have been extensively studied, over N. gonorrhoeae, A. baumannii have been tested with fewer natural extracts. Edible herbs are more often used, as well as artemisa and wine byproducts. In all cases, they are in the early stages of study, not being tested in patients at present. Conclusions: Plant extracts and plant-based compounds are effective as antibacterial, with minimal effects on the host cell. Furthermore, they are sustainable, environmentally friendly, and renewable.