An LED-Driven AuNPs-PDMS Microfluidic Chip and Integrated Device for the Detection of Digital Loop-Mediated Isothermal DNA Amplification

Abstract

The sensitive quantification of low-abundance nucleic acids holds importance for a range of clinical applications and biological studies. In this study, we describe a facile microfluidic chip for absolute DNA quantifications based on the digital loop-mediated isothermal amplification (digital LAMP) method. This microfluidic chip integrates a cross-flow channel for droplet generation with a micro-cavity for droplet tiling. DNA templates in the LAMP reagent were divided into ~20,000 water-in-oil droplets at the cross-flow channel. The droplets were then tiled in the micro-cavity for isothermal amplification and fluorescent detection. Different from the existing polydimethylsiloxane (PDMS) microfluidic chips, this study incorporates gold nanoparticles (AuNPs) into PDMS substrate through silica coating and dodecanol modification. The digital LAMP chip prepared by AuNPs-PDMS combines the benefits of the microstructure manufacturing performance of PDMS with the light-to-heat conversion advantages of AuNPs. Upon illumination with a near infrared (NIR) LED, the droplets were stably and efficiently heated by the AuNPs in PDMS. We further introduce an integrated device with a NIR heating unit and a fluorescent detection unit. The system could detect HBV (hepatitis B virus)-DNA at a concentration of 1 × 101 to 1 × 104 copies/μL. The LED-driven digital LAMP chip and the integrated device; therefore, demonstrate high accuracy and excellent performance for the absolute quantification of low-abundance nucleic acids, showing the advantages of integration, miniaturization, cost, and power consumption.

A sample-to-answer DNA detection microfluidic system integrating sample pretreatment and smartphone-readable gradient plasmonic photothermal continuous-flow PCR

“…2a, AuNRs were synthesized according to the seed-mediated growth method, modified with silica, and then dispersed in ethanol. 32 Then the AuNR-ethanol was mixed with the PDMS prepolymer and finally evaporated at 65 °C for 3 h to remove ethanol and obtain pure AuNR-PDMS. In this study, the modified silica shell can improve the dispersion of AuNRs in ethanol and PDMS and the stability under irradiation.…”

“…At present, studies have shown that a modified disposable syringe unit 50 and a cheap LED 21,32 can be used for CF-PCR liquid driving and plasmonic PCR heating, leaving room for further cost reduction and miniaturization. We will build on this paper by integrating these cheaper and smaller components and developing a fully automated fluorescence analysis application on a smartphone to bring this study closer to point-of-care testing (POCT).…”

A carbon-black-embedded poly(dimethylsiloxane)-paper hybrid device for energy-efficient nucleic-acid amplification in point-of-care testing

“…Owing to this property, photothermal materials, such as gold, silver, and copper nanoparticles can be used as heaters for nucleic acid amplication. [32][33][34] To generate heat from photothermal materials, an optical device that can provide light radiation of a specic wavelength is required.…”

A plasmonic gold nanofilm-based microfluidic chip for rapid and inexpensive droplet-based photonic PCR

“…Although AuNPs significantly improve the quality of PCR reaction by heat transfer enhancement, they may have an inhibitory effect on nucleic acid amplification at high concentrations 48 , 49 . Besides, photothermal heating using AuNPs suffers from a nonuniform distribution of nanoparticles 50 . AuNFs may be regarded as a better alternative for nucleic acid amplification than AuNPs.…”