Dielectrophoresis‐Based Protein Enrichment for a Highly Sensitive Immunoassay Using Ag/SiO2 Nanorod Arrays. Issue 12 (26th January 2018) - Cao, Zhen
Abstract: A nanoscale insulator‐based dielectrophoresis (iDEP) technique is developed for rapid enrichment of proteins and highly sensitive immunoassays. Dense arrays of nanorods (NDs) by oblique angle deposition create a super high electric field gradient of 2.6 × 10 24 V 2 m −3 and the concomitant strong dielectrophoresis force successfully traps small proteins at a bias as low as 5 V. 1800‐fold enrichment of bovine serum albumin protein at a remarkable rate of up to 180‐fold s −1 is achieved using oxide coated Ag nanorod arrays with pre‐patterned sawtooth electrodes. Based on this system, an ultrasensitive immunoassay of mouse immunoglobulin G is demonstrated with a reduction in the limit of detection from 5.8 ng mL −1 (37.6 pM) down to 275.3 fg mL −1 (1.8 f M), compared with identical assays performed on glass plates. This methodology is also applied to detect a cancer biomarker prostate‐specific antigen spiked in human serum with a detection limit of 2.6 ng mL −1 . This high sensitivity results from rapid biomarker enrichment and metal enhanced fluorescence through the integration of nanostructures. The concentrated proteins also accelerate binding kinetics and enable signal saturation within 1 min. Given the easy fabrication process, this nanoscale iDEP system provides a highly sensitive detection platform for point‐of‐care diagnostics. Abstract : An insulator‐based dielectrophoresis device integrated with versatile nanorod arrays is used for the highly effective and rapid enrichment of proteins. An immunoassay of mouse immunoglobulin G with femtomolar sensitivity is realized leveraging on this platform, referring to a 20 000‐fold enhancement in the detection limit compared with identical assays performed on glass plates.