Securinega suffruticosa (Pall.) Rehd is an excellent natural secondary shrub in the Shell Islands of Yellow River Delta. The roots of S. suffruticosa have high medicinal value and are used to treat diseases, such as neurasthenia and infant malnutrition. Any organism that is isolated from this species is of immense interest due to its potential novel bioactive compounds. In this research, the distribution and diversity of culturable endophytic fungi in S. suffruticosa were studied, and the endophytic fungi with antimicrobial activity were screened. A total of 420 endophytic fungi isolates were obtained from the S. suffruticosa grown in Shell Islands, from which 20 genera and 35 species were identified through morphological and internal transcribed spacer (ITS) sequence analyses. Chaetomium, Fusarium, Cladosporium, and Ceratobasidium were the dominant genera. The high species richness S (42), Margalef index D′ (5.6289), Shannon–Wiener index H′ (3.1000), Simpson diversity index D_s (0.9459), PIE index (0.8670), and evenness Pielou index J (0.8719) and a low dominant index λ (0.0541) indicated the high diversity of endophytic fungi in S. suffruticosa, the various species of endophytic fungi with obvious tissue specificity. The inhibition percentages of the 12 species of such endophytic fungi against Colletotrichum siamense were 3.6%-26.3%. C. globosum, Fusarium sp.3, and C. ramotenellum had a high antibacterial activity against Enterococcus faecalis, Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus. The Minimum Inhibitory Concentration (MIC) and the Minimum Bactericidal Concentration (MBC) were between 0.5 mg/mL and 2 mg/mL. Alkaloid content detection indicated that endophytic fungi had a high alkaloid content, whereas the alkaloid contents of C. globosum and Fusarium sp.3 reached 0.231% and 0.170%, respectively. Members belonging to the endophytic fungal community in the S. suffruticosa of Shell Islands that may be used as antagonists and antibacterial agents for future biotechnology applications were identified for the first time.

Near-infrared (NIR) fluorescence imaging is a noninvasive technique that provides numerous advantages for the real-time in vivo monitoring of biological information in living subjects without the use of ionizing radiation. Near-infrared fluorescent (NIRF) dyes are widely used as fluorescent imaging probes. These fluorescent dyes remarkably decrease the interference caused by the self-absorption of substances and autofluorescence, increase detection selectivity and sensitivity, and reduce damage to the human body. Thus, they are beneficial for bioassays. Indole heptamethine cyanine dyes are widely investigated in the field of near-infrared fluorescence imaging. They are mainly composed of indole heterocyclics, heptamethine chains, and N-substituent side chains. With indole heptamethine cyanine dyes as the parent, introducing reactive groups to the parent compounds or changing their structures can make fluorescent probes have different functions like labeling protein and tumor, detecting intracellular metal cations, which has become the hotspot in the field of fluorescence imaging of biological research. Therefore, this study reviewed the applications of indole heptamethine cyanine fluorescent probes to metal cation detection, pH, molecules, tumor imaging, and protein in vivo. The distribution, imaging results, and metabolism of the probes in vivo and in vitro were described. The biological application trends and existing problems of fluorescent probes were discussed.