Anti-enteroviral Activity of Microalgal Extracts Probed by Bionanohybrids of Quantum Dots and Viruses

Enterovirus 71 (EV71) disease currently lacks effective prevention and treatment. Developing a rapid and efficient drug-screening platform could expedite the discovery of potential anti-EV71 agents. Water-suspensible fluorescent CdSe/ZnS quantum dots (QDs) employed as imaging probes were fabricated by using amphiphilic alginate to form hydrophobic interaction with hydrophobic surfactant layer originally harnessed to stabilize QDs in organic phase. In the presence of 50 μg/mL cationic polybrene, bionanohybrids of QDs and EV71 formed via colloidal clustering of both negatively charged QDs (-7.38 mV) and EV71 (-9.27 mV) were detected to be positively charged (5.58 mV) and confirmed by transmission electron microscopy micrographs with sizes around 30-40 nm. The formation of QD-EV71 bionanohybrids was also verified by the appearance of QD fluorescence within BHK-21 cells treated with QD-EV71 bionanohybrids. Fluorescent images of BHK-21 cells, pretreated with various concentrations of allophycocyanin (APC) or C-phycocyanin (CPC) extracted from microalgae for 1 h and subsequently challenged with QD-EV71 bionanohybrids for 60 min, were taken by confocal laser scanning microscopy. According to our cell-based fluorescent imaging platform, the minimal effective anti-EV71 concentration of APC and CPC was determined to be 50 and 10 μg/mL, respectively. In summary, the present study demonstrated the infectivity of QD-EV71 bionanohybrids remained intact to be internalized by cells susceptible to EV71 and anti-EV71 effectiveness of two microalgae extracts was rapidly visualized by blocking cell entry of fluorescent imaging probes (i. e., QD-EV71 bionanohybrids)