Abstract:Transverse
isoelectric focusing, i.e., isoelectric focusing that
is normal to the fluid-flow direction, is an electrokinetic method
ideal for micro total analysis. However, a major challenge remains:
There is no electrode system integrable in a microfluidic device to
allow reliable transverse isoelectric focusing and electrokinetic
sensing. Here, we overcome this barrier by developing devices that
incorporate microelectrodes made of monolayer graphene. We find that
the electrolysis stability over time for grap… Show more
“…Furthermore, electrokinetic effects can be used to manipulate fluids and particles, drive electrochemical reactions, and enhance the sensitivity and specificity of biosensors. 66,67 By the same token, adhesion and cohesion are two important interfacial phenomena that play a crucial role in microfluidics. Adhesion refers to the attractive forces between a liquid and a solid surface, which can affect the wetting behaviour of the liquid and its ability to flow through microchannels.…”
“…Furthermore, electrokinetic effects can be used to manipulate fluids and particles, drive electrochemical reactions, and enhance the sensitivity and specificity of biosensors. 66,67 By the same token, adhesion and cohesion are two important interfacial phenomena that play a crucial role in microfluidics. Adhesion refers to the attractive forces between a liquid and a solid surface, which can affect the wetting behaviour of the liquid and its ability to flow through microchannels.…”
Enhancing the detection limit in protein analysis is essential for a wide range of biomedical applications. In typical fluorescent protein assays, this limit is constrained by the detection capacity of the photon detector. Here, we develop an approach that significantly enhances the protein detection threshold by using microscale isoelectric focusing implemented directly at the detection site on a protein sensor chip. We demonstrate that by electrically generating a localized pH environment within a radius of ∼60 μm, protein molecules can be concentrated within this range and be detected at levels over four times lower than those achieved by measurements without on-chip isoelectric focusing. We find that this detection-limit enhancement results from a dual effect: the concentrating of the protein molecules and a reduction in the diffusion-induced fluctuation. Our approach offers a simple, yet highly effective ultra-low-power all-electronic solution for substantially improving protein analysis detection limits for diverse applications, including healthcare, clinical diagnostics, and therapeutics.
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