Determination of the median lethal dose of zinc gluconate in mice and safety evaluation

BACKGROUND

Zinc Gluconate (ZG) is a safe and effective supplement for zinc. However, there is limited research on the optimal dosage for intravenous injection and the safety evaluation of animal models for ZG. This study aims to determine the safe dose range of ZG for intravenous injection in C57BL/6J mice.

METHODS

A Dose titration experiment was conducted to determine the LD50 and 95% confidence interval (95%CI) of ZG in mice. Based on the LD50, four sub-lethal doses (SLD) of ZG were evaluated. Following three injections of each SLD and monitoring for seven days, serum zinc levels were measured, and pathological changes in the liver, kidney, and spleen tissues of mice were determined by histological staining.

RESULTS

The dose titration experiment determined the LD50 of ZG in mice to be 39.6 mg/kg, with a 95%CI of 31.8-49.3 mg/kg. There was a statistically significant difference in the overall serum zinc levels (H = 36.912, P < 0.001) following SLD administration. Pairwise comparisons showed that the serum zinc levels of the 1/2 LD50 and 3/4 LD50 groups were significantly higher than those of the control group (P < 0.001); the serum zinc level of the 3/4 LD50 group was significantly higher than those of the 1/8 LD50 and 1/4 LD50 groups (P < 0.05). There was a positive correlation between the different SLDs of ZG and the serum zinc levels in mice (rs = 0.973, P < 0.001). H&E staining showed no significant histological abnormalities or lesions in the liver, kidney, and spleen tissues of mice in all experimental groups.

CONCLUSION

The appropriate dose range of ZG for intravenous injection in C57BL/6J mice was clarified, providing a reference for future experimental research.

Fluorescence turn-off strategy for sensitive detection of DNA methyltransferase activity based on DNA-templated gold nanoclusters

DNA methylation results in a variety of human diseases and the DNA methylation process is mediated by DNA methyltransferases, which have therefore become potential targets for disease treatment. In this study, a turn-off nanogold biological probe system was successfully created for determining the activity of DNA methyltransferases (M.SssI MTase). A dumbbell-shaped DNA probe with a site-recognizable region of M. SssI MTase and a fluorescent signal probe based on a DNA-templated gold nanocluster (DNA-AuNC) probe combined for the quantitative detection of M. SssI MTase. This dumbbell-shaped DNA probe was methylated by M. SssI MTase, and the dumbbell-shaped DNA probe with a methyl group was recognized by an endonuclease (GlaI) and cleaved into hairpin DNA. The dGTP was added to the 3'-OH terminus of hairpin DNA fragments in the presence of terminal deoxynucleotidyl transferase (TdT), and the hairpin DNA was extended with a G-rich sequence that can be used as an inactivation probe. When the inactivation probe was combined with the signal probe, the fluorescent signal disappeared due to the photoinduced electron transfer effect. Methyltransferase activity was then detected based on the turn-off principle of the fluorescence signal from the DNA-AuNCs. The bioprobe enabled sensitive detection of M. SssI MTase with a detection limit of 0.178 U mL^-1 and good specificity. The bioprobe demonstrated good detection efficiency in both human serum and cell lysates, and its unique fluorescence turn-off mechanism provided good resistance to interference, thus increasing its potential application in complex biological samples. Moreover, it is suitable for screening and assessing the inhibitory activity of M. SssI MTase inhibitors, and therefore has significant potential for disease diagnosis and drug discovery.

Facile Synthesis of Efficient Luminogens with AIE Features for Three-Photon Fluorescence Imaging of the Brain through the Intact Skull

Visualization of the brain in its native environment is important for understanding common brain diseases. Herein, bright luminogens with remarkable aggregation-induced emission (AIE) characteristics and high quantum yields of up to 42.6% in the solid state are synthesized through facile reaction routes. The synthesized molecule, namely BTF, shows ultrabright far-red/near-infrared emission and can be fabricated into AIE dots by a simple nanoprecipitation procedure. Due to their high brightness, large Stokes shift, good biocompatibility, satisfactory photostability, and large three-photon absorption cross section, the AIE dots can be utilized as efficient fluorescent nanoprobes for in vivo brain vascular imaging through the intact skull by a three-photon fluorescence microscopy imaging technique. This is the first example of using AIE dots for the visualization of the cerebral stroke process through the intact skull of a mouse with high penetration depth and good image contrast. Such good results are anticipated to open up a new venue in the development of efficient emitters with strong nonlinear optical effects for noninvasive bioimaging of living brain.

Gold nanoclusters for biomedical applications: toward in vivo studies

In parallel with the rapidly growing and widespread use of nanomedicine in the clinic, we are also witnessing the development of so-called theranostic agents that combine diagnostic and therapeutic properties.

Mammalian cells: a unique scaffold forin situbiosynthesis of metallic nanomaterials and biomedical applications

Nanoscale materials biosynthesis by using mammalian scaffold is green and highly biocompatible.

Recent advances in biomedical applications of fluorescent gold nanoclusters

Fluorescent gold nanoclusters (AuNCs) are emerging as novel fluorescent materials and have attracted more and more attention in the field of biolabeling, biosensing, bioimaging and targeted cancer treatment because of their unusual physicochemical properties, such as long fluorescence lifetime, ultrasmall size, large Stokes shift, strong photoluminescence, as well as excellent biocompatibility and photostability. Recently, significant efforts have been committed to the preparation, functionalization and biomedical application studies of fluorescent AuNCs. In this review, we have summarized the strategies for preparation and surface functionalization of fluorescent AuNCs in the past several years, and highlighted recent advances in the biomedical applications of the relevant fluorescent AuNCs. Based on these observations, we also give a discussion on the current problems and future developments of the fluorescent AuNCs for biomedical applications.