Unravelling the Function of the Unusual Antioxidants Ergothioneine and Ovothiol in Plants and Photosynthetic Protists

Ergothioneine and ovothiol are histidine derived thiols, predicted to provide antioxidant and cytoprotective roles. They have been identified in a small number of photosynthetic organisms. However, their biosynthesis and function in vivo has not been extensively explored. Metabolite profiling combined with genomic surveys indicated that the specificity of the SAM-methyltransferase is an important determinant of the biosynthetic pathway present, where the streptophyta exclusively synthesize ergothioneine, and green and red algae produce both ergothioneine and ovothiol. It has also demonstrated differences in the biosynthetic pathways between major lineages of the Archaeplastida and highlighted the loss of this pathway in the angiosperms. Knockout of the mpegt1 gene in the liverwort Marchantia polymorpha Tak-1 resulted in a reduction of ergothioneine and high light-induced stress showed an increase in the rate of development in the mutant strains. Knockout of the SAM-methyltransferase domain in the diatom Phaeodactylum tricornutum resulted in a loss of ovothiol B, but an accumulation of ovothiol A, an ovothiol B like compound, and ascorbate. P. tricornutum ovothiol mutant strains showed higher specific growth rates under high light compared to the wild type. This study has provided the first steps in the characterisation of these sulphur-containing histidine derivatives and developed tools including metabolite profiling techniques. It has also resulted in the generation of knockout mutants in two model organisms. The mutant strains have shown the involvement of histidine derived thiols in response to high light and provides two new systems which can be utilised to allow their wide roles and cellular functions to be more fully understood

Quantum Yield Enhancement of Carbon Quantum Dots Using Chemical-Free Precursors for Sensing Cr (VI) Ions

Quantum yield illustrates the efficiency that a fluorophore converts the excitation light into fluorescence emission. The quantum yield of carbon quantum dots (CQDs) can be altered via precursors, fabrication conditions, chemical doping, and surface modifications. In this study, CQDs were first fabricated from whole-meal bread using a chemical-free hydrothermal route, and a low quantum yield (0.81%) was obtained. The combination of whole-meal bread, soybean flour, and lemon juice generated CQDs with almost four folds of enhancement in quantum yield. Detailed characterization suggested that these CQDs were subjected to more complete hydrothermal reactions and had zwitterionic surfaces. The CQDs could selectively detect Cr (VI) ions with a limit of detection (LOD) of 8 ppm. This study shows that the enhancement of the quantum yield of CQDs does not need chemicals, and it is achievable with food precursors

A system of monitoring and analyzing human indoor mobility and air quality

Human movements in the workspace usually have non-negligible relations with air quality parameters (e.g., CO2, PM2.5, and PM10). We establish a system to monitor indoor human mobility with air quality and assess the interrelationship between these two types of time series data. More specifically, a sensor network was designed in indoor environments to observe air quality parameters continuously. Simultaneously, another sensing module detected participants' movements around the study areas. In this module, modern data analysis and machine learning techniques have been applied to reconstruct the trajectories of participants with relevant sensor information. Finally, a further study revealed the correlation between human indoor mobility patterns and indoor air quality parameters. Our experimental results demonstrate that human movements in different environments can significantly impact air quality during busy hours. With the results, we propose recommendations for future studies

In Vitro Biocompatibility of Surface Corrosion Films upon Magnesium

Biocompatibility is an essential requirement for implantable biomaterials, particularly for magnesium (Mg) and its alloys which are being pursued as biodegradable implants. In this study, the influence of corrosion-products layers upon the surface of pure Mg specimens was evaluated through direct contact with simulated body fluid. The immersion of pure Mg specimens was conducted in Dulbecco's modified Eagle's medium (DMEM) at physiological conditions over defined time durations (from 24 h to 14 d). Surface morphology, chemical composition, and cross-sectional structure of corrosion layers were examined by means of focused ion beam, scanning electron microscopy, and x-ray diffraction. Results reveal a duplex Mg(OH)2/CaPO4 corrosion layer was produced upon pure Mg as a result of immersion in DMEM, similar to the in vivo surface corrosion films observed on pure Mg in the murine artery. The concentration of Mg in the surface corrosion film decreased with immersion time, from approximately 64 wt% (1 d) to approximately 22 wt% (14 d). Conversely, Ca and P, representing the key constituents in DMEM, were incorporated in corrosion products, resulting in unique surfaces being presented to cells as a function of Mg dissolution. MG63 osteoblast proliferation assay demonstrates comparative cell viability on all corroded surfaces obtained through immersion in DMEM for 1 d, 3 d, 7 d, and 14 d, varying from 90% to 100%. Cell viability on all corroded surfaces was higher than that of bare metal surface (82%), signifying enhanced biocompatibility of corroded surfaces related to the bare metal surface

A system of monitoring and analyzing human indoor mobility and air quality

Human movements in the workspace usually have non-negligible relations with air quality parameters (e.g., CO2, PM2.5, and PM10). We establish a system to monitor indoor human mobility with air quality and assess the interrelationship between these two types of time series data. More specifically, a sensor network was designed in indoor environments to observe air quality parameters continuously. Simultaneously, another sensing module detected participants' movements around the study areas. In this module, modern data analysis and machine learning techniques have been applied to reconstruct the trajectories of participants with relevant sensor information. Finally, a further study revealed the correlation between human indoor mobility patterns and indoor air quality parameters. Our experimental results demonstrate that human movements in different environments can significantly impact air quality during busy hours. With the results, we propose recommendations for future studies

A pilot study on carbon quantum dots for bioimaging of muscle myoblasts

A pilot study on carbon quantum dots for bioimaging of muscle myoblast

Carbon Dot Therapeutic Platforms: Administration, Distribution, Metabolism, Excretion, Toxicity, and Therapeutic Potential

AbstractUltrasmall nanoparticles are often grouped under the broad umbrella term of “nanoparticles” when reported in the literature. However, for biomedical applications, their small sizes give them intimate interactions with biological species and endow them with unique functional physiochemical properties. Carbon quantum dots (CQDs) are an emerging class of ultrasmall nanoparticles which have demonstrated considerable biocompatibility and have been employed as potent theragnostic platforms. These particles find application for increasing drug solubility and targeting, along with facilitating the passage of drugs across impermeable membranes (i.e., blood brain barrier). Further functionality can be triggered by various environmental conditions or external stimuli (i.e., pH, temperature, near Infrared (NIR) light, ultrasound), and their intrinsic fluorescence is valuable for diagnostic applications. The focus of this review is to shed light on the therapeutic potential of CQDs and identify how they travel through the body, reach their site of action, administer therapeutic effect, and are excreted. Investigation into their toxicity and compatibility with larger nanoparticle carriers is also examined. The future of CQDs for theragnostic applications is promising due to their multifunctional attributes and documented biocompatibility. As nanomaterial platforms become more commonplace in clinical treatments, the commercialization of CQD therapeutics is anticipated

Recent advances in biodegradation controls over Mg alloys for bone fracture management: A review

Magnesium (Mg) alloys possess comparable physical and mechanical properties to bone, making them an outstanding candidate of implant materials for bone fracture treatment. In addition to the excellent biocompatibility, and bioactivity, the engagement of Mg alloys is key for a number of biological functionalities in the human body. The unique biodegradation nature of Mg alloy implants implies that it may not require a secondary removal procedure when the expected supporting tasks accomplish, as they may simply and safely “disappear” over time. Nonetheless, the demonstrated drawback of potentially rapid degradation, is an issue that must be addressed appropriately for Mg implants and is consequently given unique attention in this review article. Herein, the critical criteria and the state-of-the-art strategies for controlling the degradation process of Mg alloys are reported. Furthermore, future developments of biodegradable Mg and its alloys systems with satisfactory specifications for clinical trials and deployment, are discussed. This review aims to provide information to materials scientists and clinical practitioners in the context of developing practical biodegradable Mg alloys

A Green Synthesis Route to Derive Carbon Quantum Dots for Bioimaging Cancer Cells

Carbon quantum dots (CQDs) are known for their biocompatibility and versatile applications in the biomedical sector. These CQDs retain high solubility, robust chemical inertness, facile modification, and good resistance to photobleaching, which makes them ideal for cell bioimaging. Many fabrication processes produce CQDs, but most require expensive equipment, toxic chemicals, and a long processing time. This study developed a facile and rapid toasting method to prepare CQDs using various slices of bread as precursors without any additional chemicals. This fast and cost-effective toasting method could produce CQDs within 2 h, compared with the 10 h process in the commonly used hydrothermal method. The CQDs derived from the toasting method could be used to bioimage two types of colon cancer cells, namely, CT-26 and HT-29, derived from mice and humans, respectively. Significantly, these CQDs from the rapid toasting method produced equally bright images as CQDs derived from the hydrothermal method

Interfacial study of the formation mechanism of corrosion resistant strontium phosphate coatings upon Mg-3Al-4.3Ca-0.1Mn

Strontium phosphate (SrPO 4 ) conversion coatings with the ability to impart significant corrosion resistance were prepared upon magnesium alloy Mg-3Al-4.3Ca-0.1 Mn (wt.%). Scanning electron microscopy equipped with energy dispersive spectroscopy and transmission electron microscopy were also employed to characterise surface and interfacial morphology, along with the composition of the coatings. The protective performance of SrPO 4 coatings was examined by potentiodynamic polarisation curves and immersion testing. A coating-growth mechanism was proposed and correlations between processing parameters and coating quality was established. The findings herein provide new insights for design of environmentally-benign and corrosion resistant coatings upon magnesium alloys through a simple chemical conversion technique