A Microfluidic Paper Based Origami Nanobiosensor for Label Free, Ultrasensitive Immunoassays.
Microfluidic paper based analytical devices (mPADs) represent a promising platform technology for point of care diagnosis. Highly sensitive, rapid, and easy to perform immunoassays implemented on mPADs are desirable to fulfill the promise of the mPAD technology. This article reports the first microfluidic paper based origami nanobiosensor (origami mPAD) which integrates zinc oxide nanowires (ZnO NWs) and electrochemical impedance spectroscopy (EIS) biosensing mechanism, for label free, ultrasensitive immunoassays. The EIS mechanism features simple and label free assay operations which take less than 25 min to be finished, while the ZnO NWs allow covalent bonding for immobilizing probe proteins and improve the biosensing performance with such features as high surface area to volume ratios and high sensitivity to surface binding. The calibration of the device reveals an ultralow limit of detection (LOD) of 60 fg mL( 1) >100 times lower than those of existing mPADs) for rabbit immunoglobulin G in phosphate buffered saline. The detection of human immunodeficiency virus p24 antigen in human serum with a low LOD of 300 fg mL( 1) >33 times lower than that of a commercial p24 antigen test kit) is also demonstrated. This novel mPAD design offers ultrahigh sensitivity, short assay time, and ease of operation, and thus possesses significant potential for low cost, rapid molecular diagnosis of early stage diseases.
Advanced healthcare materials