Electrochemical genosensor based on RNA-responsive human telomeric G-quadruplex DNA: A proof-of-concept with SARS-CoV-2 RNA.

In this report, a facile and label-free electrochemical RNA biosensor is developed by exploiting methylene blue (MB) as an electroactive positive ligand of G-quadruplex. The electrochemical response mechanism of the nucleic acid assay was based on the change in differential pulse voltammetry (DPV) signal of adsorbed MB on the immobilized human telomeric G-quadruplex DNA with a loop that is complementary to the target RNA. Hybridization between synthetic positive control RNA and G-quadruplex DNA probe on the transducer platform rendered a conformational change of G-quadruplex to double-stranded DNA (dsDNA), and increased the redox current of cationic MB π planar ligand at the sensing interface, thereby the electrochemical signal of the MB-adsorbed duplex is proportional to the concentration of target RNA, with SARS-CoV-2 (COVID-19) RNA as the model. Under optimal conditions, the target RNA can be detected in a linear range from 1 zM to 1 µM with a limit of detection (LOD) obtained at 0.59 zM for synthetic target RNA and as low as 1.4 copy number for positive control plasmid. This genosensor exhibited high selectivity towards SARS-CoV-2 RNA over other RNA nucleotides, such as SARS-CoV and MERS-CoV. The electrochemical RNA biosensor showed DPV signal, which was proportional to the 2019-nCoV_N_positive control plasmid from 2 to 200000 copies (R2 = 0.978). A good correlation between the genosensor and qRT-PCR gold standard was attained for the detection of SARS-CoV-2 RNA in terms of viral copy number in clinical samples from upper respiratory specimens.

Impedimetric Polyaniline-Based Aptasensor for Aflatoxin B1 Determination in Agricultural Products.

An impedimetric aptasensor based on a polyaniline (PAni) support matrix is developed through the surface modification of a screen-printed carbon electrode (SPE) for aflatoxin B1 (AFB1) detection in foodstuffs and feedstuffs for food safety. The PAni is synthesized with the chemical oxidation method and characterized with potentiostat/galvanostat, FTIR, and UV-vis spectroscopy techniques. The stepwise fabrication procedure of the PAni-based aptasensor is characterized by means of cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) methods. The impedimetric aptasensor is optimized using the EIS technique, and its feasibility of detecting AFB1 in real sample matrices is evaluated via a recovery study in spiked foodstuffs and feedstuffs, such as pistachio nuts, cinnamons, cloves, corn, and soybeans, with a good recovery percentage, ranging from 87.9% to 94.7%. The charge transfer resistance (RCT) at the aptasensor interface increases linearly with the AFB1 concentration in the range of 3 × 10-2 nM to 8 × 10-2 nM, with a regression coefficient (R2) value of 0.9991 and detection limit of 0.01 nM. The proposed aptasensor is highly selective towards AFB1 and partially selective to AFB2 and ochratoxin A (OTA) due to their similar structures that differ only at the carbon-carbon double bond located at C8 and C9 and the large molecule size of OTA.

Zinc status in public health: exploring emerging research trends through bibliometric analysis of the historical context from 1978 to 2022.

The current study aims to provide a roadmap for future research by analyzing the research structures and trends in scholarly publications related to the status of zinc in public health. Only journal articles published between 1978 and 2022 are included in the refined bibliographical outputs retrieved from the Web of Science (WoS) database. The first section announces findings based on WoS categories, such as discipline heterogeneity, times cited and publications over time, and citation reports. The second section then employs VoSViewer software for bibliometric analysis, which includes a thorough examination of co-authorship among researchers, organizations, and countries and a count of all bibliographic databases among documents. The final section discusses the research's weaknesses and strengths in zinc status, public health, and potential future directions; 7158 authors contributed to 1730 papers (including 339 with publications, more than three times). "Keen, C.L." is a researcher with the most publications and a better understanding of zinc status in public health. Meanwhile, the USA has been the epicenter of research on the status of zinc in public health due to the highest percentage of publications with the most citations and collaboration with the rest of the world, with the top institution being the University of California, Davis. Future research can be organized collaboratively based on hot topics from co-occurrence network mapping and bibliographic couplings to improve zinc status and protect public health.

The integration of nature values and services in the nature-based solution assessment framework of constructed wetlands for carbon-water nexus in carbon sequestration and water security.

As the climate change impacts are expected to become increasingly disruptive, affecting water security, environmental health and ecosystem, constructed wetlands receive attention for their functions in delivering various life-sustaining services to human and environmental systems. In this article, a systematic review was conducted through the Preferred Reporting Items for Systematic Reviews and Meta-Analyses standard to identify the current research on constructed wetlands' nature values and services from 2011 to 2020 of two databases, namely Scopus and Web of Science. The criteria of assessment focus on holistic deliberation of subject matters, namely carbon sequestration and water security as regulating and provisioning services, as well as nature values of constructed wetlands, namely instrumental and intrinsic values. As a result, 38 articles were selected and comprehensively examined. As the lack of an interdisciplinary approach makes data and information integration difficult, this study derived an integrated classification of constructed wetlands' services and mapped with its nature values, guided by the Millennium Ecosystem Assessment framework. Besides, mechanisms and factors affecting carbon sequestration and water security were also discussed. The carbon-water nexus was then conceptualised as interlinkages between engineered and natural physicochemical processes at the interface between carbon and water cycles. To fill the gaps, based on the carbon-water nexus concept, a new framework was synthesised at the end of the deliberation for constructed wetlands in regulating local climate through carbon sequestration and ensuring water security through water treatment and purification as well as influencing socio-cultural values, which needs an integrated approach that is the novelty of this work. The framework integrates the dichotomy of the instrumental-intrinsic nature values of constructed wetlands to evaluate the importance and benefit of the carbon-water nexus. The framework that reveals the vitality of nature values provided by constructed wetlands can help improve the decision-making to prioritise ecosystem services and conservation efforts, particularly in the sustainable management of constructed wetlands.

Bio-Doped Microbial Nanosilica as Optosensing Biomaterial for Visual Quantitation of Nitrite in Cured Meats.

A microbial optosensor for nitrite was constructed based on biomimetic silica nanoparticles, which were doped with R5, a polypeptide component of silaffin, as a robust biosilica immobilization matrix entrapped with Raoultella planticola and NAD(P)H cofactor during the in vitro biosilicification process of silica nanoparticles. Ruthenium(II)(bipy)2(phenanthroline-benzoylthiourea), the chromophoric pH probe, was physically adsorbed on the resulting biogenic nanosilica. Optical quantitation of the nitrite concentration was performed via reflectance transduction of the bio-doped microbial nanosilica at a maximum reflectance of 608 nm, due to the deprotonation of phen-BT ligands in the ruthenium complex, while the intracellular enzyme expression system catalyzed the enzymatic reduction of nitrite. Reflectance enhancement of the microbial optosensor was linearly proportional to the nitrite concentration from 1−100 mg L−1, with a 0.25 mg L−1 limit of detection and a rapid response time of 4 min. The proposed microbial optosensor showed good stability of >2 weeks, great repeatability for 5 repetitive assays (relative standard deviation, (RSD) = 0.2−1.4%), high reproducibility (RSD = 2.5%), and a negligible response to common interferents found in processed meats, such as NO3−, NH4+, K+, Ca2+, and Mg2+ ions, was observed. The microbial biosensor demonstrated an excellent capacity to provide an accurate estimation of nitrite in several cured meat samples via validation using a standard UV-vis spectrophotometric Griess assay.

Establishing mercury-free medical facilities: a Malaysian case study.

PURPOSE: Mercury is widely used in medical and healthcare facilities as dental amalgam, mercury-added medical devices, thiomersal-containing vaccines, laboratory analysis and for other general applications despite the hazards. Various agencies consistently promote mercury-free medical facilities through mercury-free alternatives and better management practices, which are in line with the Minamata Convention on Mercury that aims to protect human health and environment from anthropogenic mercury release. The paper aims to discuss these issues. DESIGN/METHODOLOGY/APPROACH: The authors conducted a gap analysis on recommended practices gathered from the literature and current practices gathered through semi-structured interviews with Malaysian medical personnel. A life cycle approach was adopted covering mercury use: input, storage, handling, accident, waste disposal and governance phases. FINDINGS: The authors found that there are significant gaps between recommended and current mercury management practices. Analysis indicates improper mercury management as the main contributor to these gaps. The authors found from recommended practices that core components needing improvement include: mercury management action plan, mercury use identification team, purchasing policy, proper guidelines and monitoring systems. PRACTICAL IMPLICATIONS: This study helps us to understand mercury management practices and suggests essential steps to establish a mercury-free medical facility. ORIGINALITY/VALUE: This study explored the gaps between recommended and current mercury management practices in a medical facility and contributes to the Minamata Convention on Mercury aspirations.

Mercury-Added Products Management: Challenges In Developing Countries And Lessons Learned From Medical Facility

The risks of mercury use have prompted the establishment of Minamata Convention on Mercury which placed strong emphasis on management of mercury-added products. This convention aims to reduce and phase out the use, manufacturing and trade of mercury-added products including batteries, switches and non-electronic measuring devices. This commitment will cause significant impacts especially in the developing countries in designing the right approach to achieve it. This is also true for medical industry which is well known for the utilization of mercury-added devices and dental amalgam in its services but had embarked on efforts in eliminating mercury for many years. The experiences learned within a medical facility can be useful in efforts to meet this global ambition of mercury phase out. This paper aims to provide conceptual discussion on the challenges faced by developing countries and lessons learned from medical facility that can helps the formulation of appropriate approaches to manage mercury-added products. The paper adopted medical industry as a case study and used document analysis to discuss the issue. The main challenges identified for developing countries include lacks of capacity, funding, data and newer technologies. Based on analysis of previous studies, this study proposed a mercury management framework in medical facility and identified the recommended practices, namely technological application, policy instrument, capacity building and guidelines development. These identified approaches are found to have specific relationships between cost and potential impacts, hence giving flexibility for adoption based on the available resources in promoting better mercury management system