Ultrasensitive Detection of MicroRNA in Human Saliva via Rolling Circle Amplification Using a DNA-Decorated Graphene Oxide Sensor.

MicroRNAs (miRNAs) are a family of conserved small noncoding RNAs whose expression is associated with many diseases, including cancer. Salivary miRNAs are gaining popularity as noninvasive diagnostic biomarkers for cancer and other systemic disorders, but their use is limited by their low abundance and complicated detection procedure. Herein, we present a novel self-assembly approach based on rolling circle amplification (RCA) and graphene oxide (GO) for the ultrasensitive detection of miRNA21 and miRNA16 (miRNA oral cancer biomarkers in human saliva). First, target miRNA hybridizes with the RCA template. In the presence of DNA polymerase, the RCA reaction is induced and sequences matching the template are generated. Then, a nicking enzyme cuts the long ssDNA product into tiny pieces to obtain the amplified products. The DNA-decorated GO sensor was fabricated by preabsorbing the ssDNA fluorescence-labeled probe on the GO surface, resulting in fluorescence quenching. The DNA-decorated GO sensor could detect the amplified product via the self-assembly of dsDNA, leading to the desorption and recovery of the fluorescence-labeled probe. Under optimal conditions, the proposed system exhibited ultrasensitive detection; the detection limits of miRNA16 and miRNA21 were 8.81 and 3.85 fM, respectively. It showed a wide range of detection between 10 fM and 100 pM for miRNA16 and between 10 fM and 1 nM for miRNA16. It demonstrated high selectivity, distinguishing between 1- and 3-mismatch nucleotides in target miRNA. Overall, our proposed DNA-decorated GO sensor can accurately detect the salivary miRNAs and may potentially be used for the diagnosis and screening of early-stage oral cancer.

Isothermal Amplification Technology for Disease Diagnosis.

Isothermal amplification (IA) is a nucleic acid amplification technology (NAAT) that has contributed significantly to the healthcare system. The combination of NAAT with a suitable detection platform resulted in higher sensitivity, specificity, and rapid disease diagnosis. Traditional NAAT, such as polymerase chain reaction (PCR), is widely applied in the general healthcare system but is rarely accessed in resource-limited hospitals. Some IA methods provide a rapid, sensitive, specific, and simple method for disease diagnosis. However, not all IA techniques have been regularly used in clinical applications because different biomarkers and sample types affect either the enzyme in the IA system or sample preparation. This review focuses on the application of some IA techniques that have been applied in the medical field and have the potential for use at points of care.

Stimuli-Responsive DNA Origami Nanodevices and Their Biological Applications.

DNA origami nanotechnology has provided predictable static nanoarchitectures and dynamic nanodevices with rationally designed geometries, precise spatial addressability, and marked biocompatibility. Multiple functional elements, such as peptides, aptamers, nanoparticles, fluorescence probes, and proteins, etc. can be easily integrated into DNA origami templates with nanoscale precision, leading to a variety of promising applications. Triggered by chemical/physical stimuli, dynamic DNA origami nanodevices can switch between defined conformations or translocate autonomously, providing powerful tools for intelligent biosensing and drug delivery. In this minireview, we summarize the recent progress of dynamic DNA origami nanodevices with desired reconfigurability and feasibility to perform multiple biological tasks. We introduce varieties of DNA nanodevices that can be controlled by different molecular triggers and external stimuli. Subsequently, we highlight the recent advances in employing DNA nanodevices as biosensors and drug delivery vehicles. At last, future possibilities and perspectives are also discussed.