Label free ultrasensitive detection of NS1 based on electrochemical aptasensor using polyethyleneimine aggregated AuNPs

To date, NS1 viral diagnostic technologies have been considered as time-consuming, expensive and too complex to be widely deployed, particularly in developing countries. In view of this, an electrochemical method was exploited to detect dengue virus based on NS1-specific aptamer and cationic polymer-induced aggregation of gold nanoparticles (AuNPs). The basic principle of this assay is classical based on the gradual aggregation of AuNPs controlled by the specific interactions among polyethyleneimine (PEI), aptamer and NS1. The aggregation of AuNPs was induced by the cationic polymer, which was controlled by the interaction of aptamer and cationic polymer forming "duplex" structure. This non-specific interaction between aptamer and polymer was expected to limit the flexibility of the aptameric chain and consequently renders the aptamer to be more accessible to the target molecule (NS1). This accession of NS1 was responsible for the quadruplexe formation due to strong obligatory electrostatic interaction with aptamer. This structural switching between aptamer/polymer duplex and aptamer/target complex was the base to design this electrochemical aptasensor. This cationic polymer and aptamer assisted dispersion-aggregation phenomenon renders change in their electrochemical response which could eventually probe the sensitive detection of NS1 protein. The as prepared electrochemical aptasensor successfully detected NS-1 protein with enhanced limit of detection (0.3 ng mL(-1)) and linear range (3-160 ng mL(-1)). Human real serum analysis indicated the actual applicability of our E-Apts. Using this electrochemical aptasensor, we demonstrate the highly sensitive and specific detection of Dengue virus. The low-cost and flexibility inherent in this analytical technique could be an important step towards effective diagnostic technology for the detection of Dengue virus and other infectious diseases.