Enzyme-Free and Label-Free Ultrasensitive Electrochemical Detection of Human Immunodeficiency Virus DNA in Biological Samples Based on Long-Range Self-Assembled DNA Nanostructures

Biosensors based on nanomaterials have been used for detection of various biological molecules with high sensitivity and selectivity. Herein, we developed a simple and ultrasensitive electrochemical DNA biosensor using long-range self-assembled DNA nanostructures as carriers for signal amplification, which can achieve an impressive detection limit of S aM human immunodeficiency virus (HIV) DNA even in complex biological samples. In this study, we designed two auxiliary probes. A cascade of hybridization events between the two auxiliary probes can lead to long-range self-assembly and form micrometer-long one-dimensional DNA nanostructures. In the presence of target DNA, each copy of the target can act as a trigger to connect a DNA nanostructure to a capture probe on the electrode surface. Then, a great amount of redox indicator [Ru(NH3)(6)](3+) can be electrostatically bound to the DNA nanostructures and eventually result in significantly amplified electrochemical signals.