Joule heating is a primary limitation in slab gel electrophoresis which is a gold standard method in biochemistry and biotechnology. In this paper, we introduced an innovative new class of heat transfer nanocomposites engineered by the inclusion of metal oxide nanoparticles (NPs) in a conventional separation medium (gel). The nanocomposite exhibits high thermal conductivity compared to the gel itself. The results suggest a unique correlation between the average particle size and the thermal conductivity of the metal oxide NPs with a resolution improvement in the separation, i.e. a reduction in Joule heating. Ceria, zirconia, tungsten oxide, and lanthania NPs were loaded into agarose gel separately and used as a separation medium for gel electrophoresis. Among the NPs, ceria with the smallest size (5.2 nm) and highest thermal conductivity (17 W m-1 K-1) presented a better performance in reduction of Joule heating. By loading 0.3% (m/v) ceria, zirconia, and tungsten oxide NPs into the agarose gel at 25 o C, the thermal conductivity of the gel increased by 79, 78, and 78%, and resulted in a 22, 18, and 14% reduction in Joule heating (230 V), respectively. The overall separation efficiency and resolution increased for the agarose/zirconia gel as compared with the pure agarose gel. For example, the separation efficiency of the 70 and 80 (bp) peaks increased by 260 and 165%, respectively. Also, the resolution increased from 1.65 for the pure agarose gel to 6.32 for the agarose/zirconia gel.

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