An Integrated Micro-Heating System for On-Chip Isothermal Amplification of African Swine Fever Virus Genes.

The loop-mediated isothermal amplification (LAMP) is widely used in the laboratory to facilitate rapid DNA or RNA detection with a streamlined operational process, whose properties are greatly dependent on the uniformity and rise rate of temperature in the reaction chambers and the design of the primers. This paper introduces a planar micro-heater equipped with an embedded micro-temperature sensor to realize temperature tunability at a low energy cost. Moreover, a control system, based on the Wheatstone bridge and proportional, integral, and derivative (PID) control, is designed to measure and adjust the temperature of the micro-heater. The maximum temperature rise rate of the designed micro-heater is ≈8 °C s-1, and it only takes ≈60 s to reach the target temperature. Furthermore, a designed plasmid, containing the B646L gene of African Swine Fever Virus (ASFV), and a set of specific primers, are used to combine with the designed micro-heating system to implement the LAMP reaction. Finally, the lateral flow assay is used to interpret the amplification results visually. This method can achieve highly sensitive and efficient detection of ASFV within 40 min. The sensitivity of this on-chip gene detection method is 8.4 copies per reaction, holding great potential for applications in DNA and RNA amplification.

Theoretical Investigation on the Metamaterials Based on the Magnetic Template-Assisted Self-Assembly of Magnetic-Plasmonic Nanoparticles for Adjustable Photonic Responses.

The assembly of artificial nano- or microstructured materials with tunable functionalities and structures, mimicking nature's complexity, holds great potential for numerous novel applications. Despite remarkable progress in synthesizing colloidal molecules with diverse functionalities, most current methods, such as the capillarity-assisted particle assembly method, the ionic assembly method based on ionic interactions, or the field-directed assembly strategy based on dipole-dipole interactions, are confined to focusing on achieving symmetrical molecules. But there have been few examples of fabricating asymmetrical colloidal molecules that could exhibit unprecedented optical properties. Here, we introduce a microfluidic and magnetic template-assisted self-assembly protocol that relies mainly on the magnetic dipole-dipole interactions between magnetized magnetic-plasmonic nanoparticles and the mechanical constraints resulting from the specially designed traps. This novel strategy not only requires no specific chemistry but also enables magnetophoretic control of magnetic-plasmonic nanoparticles during the assembly process. Moreover, the assembled asymmetrical colloidal molecules also exhibit interesting hybridized plasmon modes and produce exotic optical properties due to the strong coupling of the individual nanoparticle. The ability to fabricate asymmetrical colloidal molecules based on the bottom-up method opens up a new direction for the fabrication of novel microscale structures for biosensing, patterning, and delivery applications.