Chemical Structure Research Articles

Chemical Annealing Restructures RNA for Nanopore Detection.

RNA is a key biochemical marker, yet its chemical instability and complex secondary structure hamper its integration into DNA nanotechnology-based sensing platforms. Relying on the denaturation of the native RNA structure using urea, we show that restructured DNA/RNA hybrids can readily be prepared at room temperature. Using solid-state nanopore sensing, we demonstrate that the structures of our DNA/RNA hybrids conform to the design at the single-molecule level. Employing this chemical annealing procedure, we mitigate RNA self-cleavage, enabling the direct detection of restructured RNA molecules for biosensing applications.

A comprehensive study on the identification and characterization of degradation products of lipoglycopeptide Dalbavancin using LC and LC-HRMS/MS.

Dalbavancin is the second-generation approved semisynthetic lipoglycopeptide by the United States Food and Drug Administration (USFDA) for the treatment of acute bacterial skin and skin-structure infections. Unlike other lipoglycopeptides, the stability behavior of Dalbavancin was least explored, which is a prerequisite. The current study endeavors to elucidate the oxidative and hydrolytic stability behavior of Dalbavancin by exposing the drug to oxidative, acidic, and basic stress conditions. A simple liquid chromatography (LC) method was developed, where significant resolution between Dalbavancin, its homologs, and the generated degradation products was achieved. Seven degradation products were identified under acidic, basic, and oxidative stress conditions. Using liquid chromatography and high-resolution mass spectrometry (LC-HRMS), MS/MS studies, the generated degradation products were identified and characterized. Formation of isomeric degradation products was identified especially upon exposure to basic stress conditions. The mechanistic fragmentation pathway for the seven degradation products was established, and the chemical structure for the identified degradation products was elucidated. The results strongly suggest that Dalbavancin is highly susceptible to degradation under oxidative and hydrolytic stress conditions. This study provides insights into the hydrolytic and oxidative stability of Dalbavancin, which can be employed during drug development and discovery in synthesizing relatively stable analogs.

Citrate-buffered Yamanaka medium allows to produce high-yield bacterial nanocellulose in static culture using Komagataeibacter strains isolated from apple cider vinegar

Bacterial nanocellulose (BNC) is a sustainable, renewable, and eco-friendly nanomaterial, which has gained great attentions in both academic and industrial fields. Two bacterial nanocellulose-producing strains (CVV and CVN) were isolated from apple vinegar sources, presenting high 16S rRNA gene sequence similarities (96%–98%) with Komagataeibacter species. The biofilm was characterized by scanning electron microscopy (SEM), revealing the presence of rod-shaped bacteria intricately embedded in the polymeric matrix composed of nanofibers of bacterial nanocellulose. FTIR spectrum and XRD pattern additionally confirmed the characteristic chemical structure associated with this material. The yields and productivities achieved during 10 days of fermentation were compared with Komagataeibacter xylinus ATCC 53524, resulting in low levels of BNC production. However, a remarkable increase in the BNC yield was achieved for CVV (690% increase) and CVN (750% increase) strains at day 6 of the fermentation upon adding 22 mM citrate buffer into the medium. This effect is mainly attributed to the buffering capacity of the modified Yakamana medium, which allowed to maintain pH close to 4.0 until day 6, though in combination with additional factors including stimulation of the gluconeogenesis pathway and citrate assimilation as a carbon source. In addition, the productivities determined for both isolated strains (0.850 and 0.917 g L−1 d−1) compare favorably to previous works, supporting current efforts to improve fermentation performance in static cultures and the feasibility of scaling-up BNC production in these systems.

Mechanistic insight into heteroatom removal from vacuum gas oil blended with PMMA or PET waste.

This work analyzes vacuum gas oil (VGO) and hydrocracking products of feed blended with polymethylmethacrylate (PMMA) or polyethylene terephthalate (PET) in depth to clarify the oxygen, nitrogen, and sulfur removal pathways in these complex mixtures. Hydrocracking reactions are conducted in a semi-batch reactor with a Pt-Pd/HY bifunctional catalyst at 400 °C and 80 bar for 300 min with 10 wt% waste plastic using 0.1 catalyst/feed weight ratio. The samples are analyzed using various techniques, including high-resolution mass spectrometry, providing an improved, more detailed analytical representation. The results demonstrate the synergistic effect of cofeeding oxygenated plastics to the VGO, altering the preferential reaction pathways of heteroatom-containing species in the following order: nitrogen, oxygen, and sulfur. We assess the chemical structures from the gathered data, establish plausible reaction mechanisms, and evaluate the catalyst's role.

Unveiling the Shadows: Overcoming Bottlenecks in Scaling Organic Photovoltaic Technology from Laboratory to Industry

AbstractOrganic photovoltaic (OPV) technology has recently achieved remarkable progress in academia, attaining power conversion efficiencies exceeding 19%, a breakthrough previously unimaginable. Despite these advancements, the translation of high‐efficiency OPV cells into the commercialization of OPV modules has been limited, impeding the market penetration of OPV technology. Upon careful examination, various challenges emerge, including disparities between laboratory research and industrial production in device architecture, influenced by considerations of cost and manufacturability. Additionally, the incorporation of high‐efficiency materials requires careful consideration not only of the compatibility between the photoactive layer and interface layers or transparent electrodes but also of the associated synthetic complexity of chemical structures and cost implications. While these issues are crucial, they may not be widely discussed in current mainstream research. In this article, the purpose is to identify bottlenecks from a material techniques perspective, with the aim of promoting increased resources in the research of pertinent module technologies. This effort is intended to propel OPV technology toward greater success and bring it into closer alignment with the goals of commercialization.

Structural and chemical study of complex silver patterns additively manufactured by multi-photon reduction.

Multi-photon reduction (MPR) based on femtosecond laser makes rapid prototyping and molding in micro-nano scale feasible, but is limited in material selectivity due to lack of the understanding of the reaction mechanism in MPR process. In this paper, additively manufacturing of complex silver-based patterns through MPR is demonstrated. The effects of laser parameters, including laser pulse energies and scanning speeds, on the structural and chemical characteristics of the printed structures are systematically investigated. The results show that the geometric size of printed cubes deviates from the designed size further by increasing laser pulse energies or decreasing scanning speeds. The reaction mechanism of MPR is revealed by studying the elemental composition and chemical structures of printed cubes. The evolution of Raman spectra upon the laser processing parameters suggests that the MPR process mainly includes two processes: reduction and decomposition. In the MPR process, silver ions are reduced and grow into particles by accepting the electrons from ethonal molecules; meanwhile carboxyl groups in polyvinylpyrrolidone are decomposed and form amorphous carbon that is attached on the surface of silver particles. The conductivity of silver wires fabricated by MPR reaches 2×105 S/m and stays relatively constant as varying their cross section area, suggesting excellent electrical conduction. The understanding of the MPR process would accelerate the development of MPR technology and the implementation of MPR in micro-electromechanical systems could therefore be envisioned.

Gonadotropin-Releasing Hormone (GnRH) and Its Agonists in Bovine Reproduction I: Structure, Biosynthesis, Physiological Effects, and Its Role in Estrous Synchronization.

GnRH is essential for the regulation of mammalian reproductive processes. It regulates the production and release of pituitary gonadotropins, thereby influencing steroidogenesis and gametogenesis. While primarily produced in the hypothalamus, GnRH is also produced in peripheral organs, such as the gonads and placenta. GnRH analogs, including agonists and antagonists, have been synthesized for the reproductive management of animals and humans. This review focuses on the functions of hypothalamic GnRH in the reproductive processes of cattle. In addition to inducing the surge release of LH, the pulsatile secretion of GnRH stimulates the pituitary gland to release FSH and LH, thereby regulating gonadal function. Various GnRH-based products have been synthesized to increase their potency and efficacy in regulating reproductive functions. This review article describes the chemical structures of GnRH and its agonists. This discussion extends to the gene expression of GnRH in the hypothalamus, highlighting its pivotal role in regulating the reproductive process. Furthermore, GnRH is involved in regulating ovarian follicular development and luteal phase support, and estrus synchronization is involved. A comprehensive understanding of the role of GnRH and its analogs in the modulation of reproductive processes is essential for optimizing animal reproduction.

Effect of Oligoricinoleic Acid on Degradation of Polylactic Acid

ABSTRACT The objective of this research is to explore the impact of oligoricinoleic acid (ORA) on the degradation of polylactic acid (PLA). ORA was synthesized from ricinoleic acid using tin (II) 2-ethylhexanoate as a catalyst. The chemical structures of the obtained ORA were confirmed by Fourier-transform infrared spectrometer (FT-IR) and proton nuclear magnetic resonance spectroscopy (1H-NMR). PLA/ORA films were prepared through the casting method by varying ORA concentrations as 0.1%wt, 0.3%wt, 0.5%wt, 1.0 wt%, and 3.0%wt. Degradation of the films via hydrolysis was studied by soaking the films in deionized water and stirring at 120 rpm in an incubator at 37°C. Alterations in the structure and properties of the films were investigated after soaking for 7, 14, 21, and 28 days using ultraviolet-visible spectroscopy (UV-Vis), Fourier-transform infrared spectrometer (FTIR), scanning electron microscope (SEM), X-ray diffraction (XRD), differential scanning calorimeter (DSC), thermogravimetric analysis (TGA), and universal testing machine (UTM). Gel permeation chromatography (GPC) was performed to confirm the decrease in molecular weight (MW). The presence of 3%wt ORA could promote both ductility and degradation of PLA films. ORA further enhances thermal stability, indicating potential for prevention of thermal degradation during melt processing.

Important antiviral properties of Streptomyces species compounds

species, a subgroup of Actinomycetes bacteria, have been analysed for their antiviral properties. These bioactive secondary metabolites, which have a broad spectrum of chemical structures and strong biological activity, offer a promising opportunity for new antiviral therapeutics against various viral infections. These metabolites target different stages of viral replication or interactions with host cells, making them important for biological research and pharmaceutical development. bacteria contain numerous antiviral mechanisms that inhibit viral infections at different stages of the viral life cycle. and other actinomycetes can improve the health of people with viruses, and recent research suggests that combining with other bacterial species could improve overall health and regulate infections. This emphasises the importance of comprehensive approaches to combating viral infections and research into natural products. Further research into multispecies combinations of and other bacterial species is needed to fully utilise their therapeutic potential against viral diseases.

Determining glycosyltransferase functional order via lethality due to accumulated O-antigen intermediates, exemplified with Shigella flexneri O-antigen biosynthesis.

The O antigen (OAg) polysaccharide is one of the most diverse surface molecules of Gram-negative bacterial pathogens. The structural classification of OAg, based on serological typing and sequence analysis, is important in epidemiology and the surveillance of outbreaks of bacterial infections. Despite the diverse chemical structures of OAg repeating units (RUs), the genetic basis of RU assembly remains poorly understood and represents a major limitation in assigning gene functions in polysaccharide biosynthesis. Here, we describe a genetic approach to interrogate the functional order of glycosyltransferases (GTs). Using Shigella flexneri as a model, we established an initial glycosyltransferase (IT)-controlled system, which allows functional order allocation of the subsequent GT in a 2-fold manner as follows: (i) first, by reporting the growth defects caused by the sequestration of UndP through disruption of late GTs and (ii) second, by comparing the molecular sizes of stalled OAg intermediates when each putative GT is disrupted. Using this approach, we demonstrate that for RfbF and RfbG, the GT involved in the assembly of S. flexneri backbone OAg RU, RfbG, is responsible for both the committed step of OAg synthesis and the third transferase for the second L-Rha. We also show that RfbF functions as the last GT to complete the S. flexneri OAg RU backbone. We propose that this simple and effective genetic approach can be also extended to define the functional order of enzymatic synthesis of other diverse polysaccharides produced both by Gram-negative and Gram-positive bacteria.IMPORTANCEThe genetic basis of enzymatic assembly of structurally diverse O antigen (OAg) repeating units (RUs) in Gram-negative pathogens is poorly understood, representing a major limitation in our understanding of gene functions for the synthesis of bacterial polysaccharides. We present a simple genetic approach to confidently assign glycosyltransferase (GT) functions and the order in which they act during assembly of the OAg RU. We employed this approach to determine the functional order of GTs involved in Shigella flexneri OAg assembly. This approach can be generally applied in interrogating GT functions encoded by other bacterial polysaccharides to advance our understanding of diverse gene functions in the biosynthesis of polysaccharides, key knowledge in advancing biosynthetic polysaccharide production.

Health Risk Associated with Conventional Skin Lighteners and Female Civil Servants’ Comprehension of Skin Lightening Ingredient Information in Anambra State

Skin-lightening products have been in use for many years to lighten skin colour. However, these products contain chemicals that can alter the skin's chemical structure and inhibit the production of melanin. Therefore, users of these products need to understand the ingredients and the potential health risks associated with their use. A study was conducted to assess the health risks associated with conventional skin-lightening products and to determine how well female civil servants understood the ingredient information on the product packaging. The study aimed to determine how many women read the ingredient information on these products, how many understood the information, and how many were aware of the health risks associated with their use. The study was conducted as a survey of 348 civil servants from 21 Ministries in Anambra State using an online sample size calculator. The study was anchored on the Individual Difference theory and selective perception media effect. The survey found that a significant number of female civil servants in Anambra state do not read the ingredient information on skin-lightening products. It was also discovered that the majority of female civil servants in Anambra State do not comprehend the product ingredient information because of its technical nature. Despite this, the study found that most women were aware of the health risks associated with the use of these products. The study concluded that female civil servants in Anambra State were aware of the ingredient information composition on skin-lightening products, but did not read it, making it difficult for them to understand and interpret the information. However, most of these women were still aware of the health risks associated with the use of skin-lightening products but still used them because of the benefits they claimed to have experienced. The study recommended that manufacturers and brand designers should simplify the technical language used to describe the product ingredients to make it easier for users to understand. Additionally, regulatory agencies like NAFDAC and SON should ensure that manufacturers produce skin products that do not contain harmful chemicals like hydroquinone, corticosteroids, and mercury. If these chemicals are used, users should be informed of the negative side effects.

Reinforcing effects of ground tyre rubber on physical, mechanical, and thermal properties of polyethylene terephthalate

This study examines the use of waste and recyclable polyethylene terephthalate (rPET) along with micro-sized ground tire rubber (GTR) to produce a polymer matrix composite (PMC) material. The PMC materials are made in a Twin-screw extruder, with different ratios of rPET to GTR ranging from 90:10 to 50:50. In order to assess the performance of the newly created rPET-GTR matrix composite materials, the physical, mechanical properties are empirically observed. The thermal properties and crystallinity (Xc) of PMC materials are analysed using DSC. SEM and microscopic imaging are used to determine the characteristics of rPET-GTR composite materials, including elemental compositions like carbon, oxygen, and silicon. The functional group and chemical structure are confirmed through IR spectra analysis using FTIR techniques. The inclusion of micro-sized GTR has shown a significant effect on the physical (density = 1.306 - 1.208 g/cm3, water absorption = 1.76%–10.74%, and melt flow index = 8.12 - 12.79 gm/10 min), mechanical (tensile strength = 52.78 – 73.58 MPa, impact strength = 110.64 - 138.44 J/m, hardness = 56.14 - 76.37, and flexural modulus = 66.23 - 106.32 MPa), and thermal (melting temperature = 220.25°C–192.57°C, Xc = 20.30 to 30.58%) properties of rPET. These studies all work together to improve the performance of waste rPET and GTR materials by repurposing them. It helps to promote sustainability, cost-effectiveness, and expands the range of applications (automotive parts, building materials, sports equipment, electrical insulation and prosthetics) for rPET-based composites with potential uses in the polymer industries.

Applications of multi-parameter sensing in pharmaceutical, agriculture and mineral industries using THz spectroscopy and Low-Wavenumber Raman spectroscopy

Multi-parameter sensing using non-destructive optical spectroscopic techniques, specifically Terahertz spectroscopy and low-wavenumber Raman spectroscopy (also known as THz-Raman spectroscopy), has significantly reshaped the landscape of analytical methodologies in various industries. This comprehensive review article elucidates the transformative impact of these advanced spectroscopic methods within the fields of pharmaceutical, agriculture, and mineral industry. As technology continues to evolve, the ability to concurrently analyse multiple parameters at the molecular level has become a cornerstone for precision and efficiency in these critical sectors. In the pharmaceutical industry, THz spectroscopy has emerged as a key tool in ensuring the quality and stability of drug formulations, while low-wavenumber Raman spectroscopy complements by offering insights into chemical structure as well as composition. The agricultural sector benefits from the capabilities of these spectroscopic techniques in optimizing crop management, soil analysis, and resource utilization. Simultaneously, the mineral industry leverages THz and low-wavenumber Raman spectroscopy for accurate mineral identification, aiding in exploration, extraction, and processing. Through this review, we aim to provide a nuanced understanding of how multi-parameter sensing through THz and low-wavenumber Raman spectroscopy is driving innovation, enhancing quality control, and fostering sustainable practices across diverse industrial landscapes.

Analysis of the Surface of Historic Fabric from the Auschwitz-Birkenau State Museum after Treatment with Ethanol Mist Used to Eliminate Microorganisms Harmful to Human Health.

the aim of the work was to present the changes occurring on the model and historical cotton surface of cotton resulting from disinfection with 90% ethanol mist. Samples of historical materials consisted of fabric elements from suitcases stored in A-BSM. A mist of 90% ethanol was applied for 15 s at a distance of 16 cm from the surface. The spectra of cotton samples before and after ethanol application were recorded using Fourier transform infrared spectroscopy (FTIR-ATR). Analyses of the surface layers were performed using X-ray photoelectron spectroscopy (XPS). the decontamination performed did not show any significant differences in the chemical composition and surface structure of cotton before and after the use of 90% ethanol mist. Ethanol mist, which eliminates microorganisms from the historical surface, does not cause significant changes to the surface of historical objects.

PRODIGE - Planet-forming disks in Taurus with NOEMA. II. Modeling the CO (2-1) isotopologue emission of the Class II T Tauri disks in Taurus

To understand how planets form in protoplanetary disks, it is necessary to characterize their gas and dust distribution and masses. This requires a combination of high-resolution dust continuum and molecular line interferometric observations, coupled with advanced theoretical models of protoplanetary disk physics, chemical composition, and radiative transfer. We aim to constrain the gas density and temperature distributions as well as gas masses in several T Tauri protoplanetary disks located in Taurus. We use the 12CO, 13CO, and C18O (2-1) isotopologue emission observed at $0.9 with the IRAM NOrthern Extended Millimeter Array (NOEMA) as part of the MPG-IRAM Observatory Program PRODIGE (PROtostars and DIsks: Global Evolution \, PIs: P. Caselli Th. Henning). Our sample consists of Class II disks with no evidence of strong radial substructures. We use these data to constrain the thermal and chemical structure of these disks through theoretical models for gas emission. To fit the combined optically thick and thin CO line data in Fourier space, we developed the DiskCheF code, which includes the parameterized disk physical structure, machine-learning (ML) accelerated chemistry, and the RADMC-3D line radiative transfer module. A key novelty of DiskCheF is the fast and feasible ML-based chemistry trained on the extended grid of the disk physical-chemical models precomputed with the ANDES2 code. This ML approach allows complex chemical kinetics models to be included in a time-consuming disk fitting without the need to run a chemical code. We present a novel approach to incorporate chemistry into disk modeling without the need to explicitly calculate a chemical network every time. Using this new disk modeling tool, we successfully fit the 12CO, 13CO, and C$ $O (2-1) data from the CI, CY, DL, DM, DN, and IQ Tau disks. The combination of optically thin and optically thick CO lines allows us to simultaneously constrain the disk temperature and mass distribution, and derive the CO-based gas masses. The best-fit disk gas masses range between 0.005 and $0.04 M_ sun $. These values are in reasonable agreement with the disk dust masses rescaled by a factor of 100 as well as with other indirect gas measurements via, for example, modeling of the wavelength dependence of the dust continuum emission radii, and HD and CO isotopologue emission.

Investigation of the Link between Per- and Polyfluoroalkyl Substances and Stress Biomarkers in Bottlenose Dolphins (Tursiops truncatus).

Bottlenose dolphins (Tursiops truncatus) are keystone and sentinel species in the world's oceans. We studied correlations between per- and polyfluoroalkyl substances (PFAS) and their stress axis. We investigated associations between plasma biomarkers of 12 different PFAS variants and three cortisol pools (total, bound, and free) in wild T. truncatus from estuarine waters of Charleston, South Carolina (n = 115) and Indian River Lagoon, Florida (n = 178) from 2003 to 2006, 2010-2013, and 2015. All PFAS and total cortisol levels for these dolphins were previously reported; bound cortisol levels and free cortisol calculations have not been previously reported. We tested null hypotheses that levels of each PFAS were not correlated with those of each cortisol pool. Free cortisol levels were lower when PFOS, PFOA, and PFHxS biomarker levels were higher, but free cortisol levels were higher when PFTriA was higher. Bound cortisol levels were higher when there were higher PFDA, PFDoDA, PFDS, PFTeA, and PFUnDA biomarkers. Total cortisol was higher when PFOA was lower, but total cortisol was higher when PFDA, PFDoDA, PFTeA, and PFTriA were higher. Additional analyses indicated sex and age trends, as well as heterogeneity of effects from the covariates carbon chain length and PFAS class. Although this is a cross-sectional observational study and, therefore, could reflect cortisol impacts on PFAS toxicokinetics, these correlations are suggestive that PFAS impacts the stress axis in T. truncatus. However, if PFAS do impact the stress axis of dolphins, it is specific to the chemical structure, and could affect the individual pools of cortisol differently. It is critical to conduct long-term studies on these dolphins and to compare them to populations that have no or little expose to PFAS.

Synthesis, molecular modelling, and antibacterial evaluation of new sulfonamide-dyes based pyrrole compounds

In this study, we synthesized new series of 5-oxo-2-phenyl-4-(arylsulfamoyl)sulphenyl) hydrazono)-4,5-dihydro-1H-pyrrole-3-carboxylate hybrids 4a-f with the goal of overcoming sulfonamide resistance and identifying novel therapeutic candidates by chemical changes. The chemical structures of the synthesized hybrids were established over the spectroscopic tools. The frontier molecular orbitals configuration and energetic possessions of the synthesized compounds were discovered utilizing DFT/B3LYP/6-311++ G** procedure. The 3D plots of both HOMO and LUMO showed comparable configuration of both HOMO and LUMO led to close values of their energies. Amongst the prepared analogues, the sulfonamide hybrids 4a-f, hybrid 4a presented potent inhibitory towards S. typhimurium with (IZD = 15 mm, MIC = 19.24 µg/mL) and significant inhibition with (IZD = 19 mm, MIC = 11.31 µg/mL) against E.coli in contrast to sulfonamide (Sulfamethoxazole) reference Whereas, hybrid 4d demonstrated potent inhibition with (IZD = 16 mm, MIC = 19.24 µg/mL) against S. typhimurium with enhanced inhibition against E. Coli, Additionally, the generated sulfonamide analogues’' molecular docking was estimated over (PDB: 3TZF and 6CLV) proteins. Analogue 4e had the highest documented binding score as soon as linked to the other analogues. The docking consequences were fitting and addressed with the antibacterial valuation.

Flavonoids and triterpenoids isolated from the ethyl acetate extract of Maytenus quadrangulata leaves.

The new flavonoid 4'-O-methylepigallocatechin 5-O-β-D-glucopyranoside (1), along with four known triterpenes (2-4), a steroid (6), and a flavonoid (7) were isolated from the ethyl acetate extract of Maytenus quadrangulata leaves. The chemical structures of the isolated compounds were determined through analysis of 1D NMR (1H and 13C) spectroscopic data, in addition to 2D NMR and spectrometric (MS) data for compound 1. This is the first report of the isolation of compounds 3-O-β-D-glucosyl-β-sitosterol (6) and 4'-O-methylepigallocatechin (7) from this species. Compounds 1 and 7 were evaluated against the bacteria Staphylococcus aureus and Klebsiella pneumoniae, but neither exhibited activity even at the highest concentration tested.

Direct Comparative Studies Revealing the Contribution of TADF Activity of Organic Emitters Towards Efficient Electrochemiluminescence.

Electrochemiluminescence (ECL) featuring thermally activated delayed fluorescence (TADF) properties has attracted considerable interest, showcasing their potential for 100% exciton harvesting, which marks a significant advancement in the realm of organic ECL. However, the challenge of elucidating the precise contribution of TADF to the enhanced ECL efficiency arises due to the lack of comparative studies of organic compounds with or without efficient TADF properties. In this study, we present four carbazole-benzonitrile (Cz-BN) molecules possessing similar chemical structures and comparable exchange energy (ΔEST). Despite their comparable properties, these compounds exhibited varying TADF efficiencies, warranting a closer examination of their underlying structural and electronic characteristics governing the optical properties. Consequently, intense ECL emission was only observed from 4CzBN with a remarkable TADF efficiency, underscoring the substantial difference in the ECL signal among molecules with comparable ΔEST and similar spectral properties but varying TADF activity.

Antibacterial mechanism of Malaysian Carey clay against food-borne Staphylococcus aureus

Depending on their chemical structure and geochemistry, clay minerals can display potent antibacterial properties against a range of bacterial pathogens. Malaysian Carey clay was evaluated for its antibacterial activity against food-borne Staphylococcus aureus ATCC 13565 strains. The minimum inhibitory concentration (MIC) and minimum bactericidal activity (MBC) of both Carey clay leachates and suspension were 125 mg/mL and 250 mg/mL, respectively. Time-kill assay revealed that 2x MIC and 4x MIC Carey clay in both leachate and suspension forms resulted in complete killing of S. aureus. Antibacterial mechanism was investigated through imaging of bacterial morphology using TEM and determination of reactive oxygen species (ROS) using NBT assay. Imaging of bacterial morphology using TEM showed abnormalities, including disrupted cell walls following exposure to Carey clay, and the antibacterial activity was associated with generation of ROS. Our study suggests that Carey clay displays promising functionality as a natural antibacterial agent in the food industry.