Biocompatible transition metal complexes dyes emitting in the near-infrared (NIR) region, are highly desirable in fluorescence imaging techniques. However, a high-performance mitochondria-specific labeling NIR probe with high photostability is still lacking. Herein we reported two NIR-emitting cationic iridium(III) complexes [Ir(pbq-g)₂(N^N)]⁺Cl⁻ (pbq-g = phenylbenzo[g]-quinoline; N^N = 2-(1-benzyl-1H-pyrazol-3-yl) pyridine (Ir1) and 2-(1-(naphthalen-1-ylmethyl)-1H-pyrazol-3-yl) pyridine (Ir2)). These two novel Ir(III) complexes with different N^N ligands exhibited similar NIR emission with λ_max at 751 nm for Ir1 and 750 nm for Ir2 in PBS solution, with luminescence quantum yields of around 0.62 for Ir1 and 0.85 for Ir2. These two complexes showed high mitochondrial specificity, superior photostability, high resistance to the loss of the mitochondrial membrane potential and appreciable tolerance to environmental changes, allowing NIR imaging of mitochondrial morphological changes over long periods of time. These excellent photophysical and imaging properties made them promising NIR luminescent tags for applications in bioimaging.

Poria cocos polysaccharides (PS) have been used as Chinese traditional medicine with various pharmacological effects, including antiviral, anti-oxidative, and immunomodulatory activities. Herein Bombyx mori silkworm was used as a model animal to evaluate the immunomodulatory effects of PS via detecting the changes of innate immune parameters and explore the underlying molecular mechanism of the immunoregulatory effect of PS using Illumina HiSeq Xten platform. The results presented here demonstrated that a hemocoel injection of PS significantly enhanced the cellular immunity of silkworm, including hemocyte phagocytosis, microaggregation, and spreading ability. A total of 335 differentially expressed genes (DEGs) were screened, including 214 upregulated genes and 121 downregulated genes by differential expression analysis. Gene annotation and enrichment analyses showed that many DEGs related to immune signal recognition, detoxification, proPO activation, carbohydrate metabolism, and lipid metabolism were significantly upregulated in the treatment group. The Kyoto Encyclopedia of Genes and Genomes-based Gene Set Enrichment Analysis also revealed that the more highly expressed gene sets in the PS treatment silkworm were mainly related to immune signal transduction pathways and energy metabolism. In addition, the activity of four enzymes related to immunity and energy metabolism—including phenoloxidase, glucose-6-phosphate dehydrogenase, hexokinase, and fatty acid synthetase—were all significantly increased in the larvae injected with PS. We performed qRT-PCR to examine the expression profile of immune and metabolic-related genes, which further verified the reliability of our transcriptome data and suggested that PS can regulate the immunity of silkworm by enhancing the cellular immunity and modulating the expression levels of genes related to immune responses and physiological metabolism. These findings will lay a scientific foundation for the use of PS as an immunomodulator in disease prevention in human beings or animals.