Fluorescent imaging and toxicology study of alga-derived carbon dots in zebrafish.

With the widespread application of carbon dots (CDs) in fluorescence imaging, their toxicity has become a focal point of concern. The potential toxicity of CDs synthesized from different raw materials remains an unresolved issue. Laver and wakame, which are commonly popular sea vegetable foods rich in nutrients, were utilized to investigate whether synthetic CDs derived from these alga sources retain medicinal value. Herein, two types of fluorescent alga-derived CDs were prepared through hydrothermal synthesis using laver and wakame respectively. Zebrafish were immersed in both types of CDs to observe their fluorescence imaging effects within the zebrafish bodies. It was observed that laver-derived CDs and wakame-derived CDs exhibited similar luminescence properties but differed in terms of fish egg imaging localization. Additionally, intestinal flora sequencing revealed varying degrees of influence on the zebrafish gut microbiota by the two types of CDs, suggesting that both alga-derived CDs could enhance the abundance of intestinal flora in zebrafish.

Analysis of Critical Instability Conditions for Solid-Phase Plugging of Natural Fractures during Temporary Plugging and Fracturing.

Hydraulic fracturing has become a key technology for the development of unconventional oil and gas resources, such as deep shale. Due to the development of natural fractures in deep shale reservoirs, the opening of natural fractures during the fracturing process can cause a significant loss of fracturing fluid, resulting in a reduction in the width of the main fracture and construction risks, such as sand plugging. It is important to improve the fracturing effect of deep shale reservoirs by plugging natural fractures with solid phases, reducing filtration, and improving the efficiency of the fracturing fluid. Ensuring the effectiveness of solid plugging is key to optimizing the fracturing design and improving the stimulation effect after fracturing. In this study, solid plugging technology is introduced into the filtration control process of natural fractures. By setting a plugging zone with a certain length and permeability inside the natural fracture, a stability prediction model for the plugging zone of natural fractures is established, and the instability conditions of the plugging zone are analyzed. The simulation results indicate that the instability of the plugging zone is related to permeability and there is a critical permeability. When the permeability of the plugging zone is greater than this value, expansion instability will occur, and when it is less than or equal to this value, shear slip instability may occur. The strength of shear slip instability is mainly determined by the length of the plugging zone, the friction angle of the natural fracture surface, the friction angle between the plugging particles, and the porosity of the plugging zone. The friction angle of natural fracture surfaces affects only the strength of slip instability, while the friction angle of plugging particles and porosity mainly affect the strength of shear instability. The research results provide a theoretical basis for the optimization of fracturing construction parameters in deep shale reservoirs.

Correction: Green synthesis of chlorella-derived carbon dots and their fluorescence imaging in zebrafish.

[This corrects the article DOI: 10.1039/D3RA07623G.].

Green synthesis of chlorella-derived carbon dots and their fluorescence imaging in zebrafish.

Recently, carbon dots (CDs) have been shown to exhibit exceptional water solubility, low toxicity, favorable biocompatibility, stable fluorescence properties with a wide and continuous excitation spectrum, and an adjustable emission spectrum. Their remarkable characteristics make them highly promising for applications in the field of bioimaging. Zebrafish is currently extensively studied because of its high genetic homology with humans and the applicability of disease research findings from zebrafish to humans. Therefore, spirulina, a commonly used feed additive in aquaculture, was chosen as the raw material for synthesizing fluorescent CDs using a hydrothermal method. On the one hand, CDs can modulate dopamine receptors in the brain of zebrafish, leading to an increase in dopamine production and subsequently promoting their locomotor activity. On the other hand, CDs have been shown to enhance the intestinal anti-inflammatory capacity of zebrafish. This study aimed to explore the chronic toxicity and genotoxicity of CDs in zebrafish while providing valuable insights for their future application in biological and medical fields.