This review is dedicated to offering a new perspective on using DNA nanostructures to explore the progress of cell–cell communication.

Diabetic wound repair is a global challenge due to bacterial infection and the typical microenvironments of hyperglycemia, high pH value, hypoxia, persistent inflammation and insufficient angiogenesis. Herein, a glucose-activated nitric oxide (NO) releasing and microenvironment regulation hydrogel dressing (COH-GB) has been developed for efficiently promoting infectious diabetic wound healing. Specifically, an artificial multienzyme nanoflower (GB nanoflower) composed of glucose oxidase (GOx) and hemoglobin (Hb) was synthesized and incorporated into the hydrogel formed by carboxymethyl chitosan (CMCS), oxidized sodium alginate (OSA) and hydroxyurea (HU). In which, the hyperglycemia-triggered cascade reaction could consume glucose, while providing hydrogen peroxide (H₂O₂) for the generation of NO by HU in the presence of Hb with peroxidase-mimicking activity. The COH-GB hydrogel with essential wound dressing characteristics could remodel the microenvironment of diabetic wounds by reducing local glucose and pH levels, alleviating hypoxia, and scavenging excessive ROS; and releasing NO under different blood glucose levels for antibacterial or angiogenesis. Importantly, the prepared COH-GB hydrogel significantly accelerated the MRSA-infected diabetic wound healing by effectively reducing wound infection, inhibiting inflammation, and promoting collagen deposition, angiogenesis and the migration and differentiation of fibroblasts and keratinocytes. Notably, the formation of GB nanoflowers could enhance the activity and stability of enzymes, and improve the cascade reaction efficiency, thereby inducing a more efficient performance in microenvironment regulation, antibacterial and angiogenesis, as well as wound healing. Hence, the prepared artificial multienzyme nanoflower composite hydrogel provides an efficient and secure dressing for promoting infectious diabetic wound healing via glucose-activated NO releasing and microenvironment regulation.

MicroRNAs (miRNAs) encapsulated in tumor-derived exosomes are becoming ideal biomarkers for the early diagnosis and prognosis of lung cancer. However, the accuracy and sensitivity are often hampered by the extraction process of exosomal miRNA using traditional methods. Herein, this study developed a fluorogenic quantitative detection method for exosomal miRNA using the fluorescence quenching properties of molybdenum disulfide (MoS₂) nanosheets and the enzyme-assisted signal amplification properties of duplex-specific nuclease (DSN). First, a fluorescently-labeled nucleic acid probe was used to hybridize the target miRNA to form a DNA/RNA hybrid structure. Under the action of the DSN, the DNA single strand in the DNA/RNA hybrid strand was selectively digested into smaller oligonucleotide fragments. At the same time, the released miRNA target triggers the next reaction cycle, so as to achieve signal amplification. Then, MoS₂ was used to selectively quench the fluorescence of the undigested probe leaving the fluorescent signal of the fluorescently-labeled probe fragments. The fluorometric signals for miRNA-21 had a maximum excitation/emission wavelength of 488/518 nm. Most importantly, the biosensor was then applied for the accurate quantitative detection of miRNA-21 in exosome lysates extracted from human plasma and this method was able to successfully distinguish lung cancer patients from healthy people. This biosensor provides a simple, rapid, and a highly specific quantitative method for exosomal miRNA and has promising potential to be used in the early diagnosis of lung cancer.