Dielectrophoresis (DEP) is good for manipulation of large particles like cells, since DEP force is proportional to the cube of particle size. While for small particles such as proteins, a super high electric field gradient is needed. In this work, core/shell nanorods (NDs) have been integrated into a DEP device to create the required gradient. Proteins can be concentrated at the designed spot and thus favor the protein detection. Firstly, micro-sawtooth electrodes are pre-patterned on glass substrate (a) and then three-dimensional oxide coated Ag NDs are fabricated, as shown in the cross-sectional view of the device diagram (b). A theoretical simulation has revealed that the thin oxide coating on Ag NDs, indicated by left panel of (c), creates a gradient of the electric field intensity squared as high as of 2.6×1024 V2/m3 (right panel of (c)). The above core/shell NDs based DEP device has enriched bovine serum albumin (BSA) proteins by 1800-fold when only applying 5 V electric potential. Image (d) shows fluorescent images of BSA concentration in the DEP devices integrated with/without NDs. Further, the detection of prostate-specific antigen (PSA), a cancer biomarker for diagnosis of prostate cancer after radical prostatectomy, has been performed. Briefly, specific antibodies are immobilized onto NDs, then PSA are concentrated and captured, and finally the signal from fluorescence labeled antibodies is detected. The limit of detection is measured as low as 2.6 pg/mL (e). In summary, this core/shell NDs based DEP platform poses great potentials in applications for early point-of-care diagnostics.

Core/shell nanorods based dielectrophoresis for biomarker concentration and detection

256th National Meeting (2018)

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