Mie Scatter and Interfacial Tension Based Real‐Time Quantification of Colloidal Emulsion Nucleic Acid Amplification

Abstract

This work demonstrates for the first time rapid, real‐time Mie scatter sensing of colloidal emulsion nucleic acid amplification directly from emulsion droplets. Loop‐mediated isothermal amplification is used in this study, and, to our knowledge, has not previously been used in a colloidal emulsion platform. Interfacial tension values (γ) associated with bulk protein adsorption and denaturation at the oil–water interface exhibit characteristic changes in the absence or presence of amplification. In the presence of target and amplicon, emulsions maintain a constant 300–400 nm diameter, whereas emulsions formed with no target control show a rapid decrease in droplet diameter to <100 nm over the first 20 min of incubation. This method is validated using whole bacteria (Staphylococcus aureus MSSA and Escherichia coli O157:H7) and whole virus (Potato virus Y and Zika virus) samples suspended in water, buffer, or serum‐like matrices. Short‐term formation of colloidal emulsion is quantified via 60° scatter monitoring, where the initial slope of scattering intensity is utilized to confirm target amplification in less than 5 min. The unique benefits of this method render it more cost‐effective and field‐deployable than existing methods, while being adaptable to a multitude of targets, sample matrices, and nucleic acid amplification tests.

Progression of LAMP as a Result of the COVID-19 Pandemic: Is PCR Finally Rivaled?

“…Various methods, such as the addition of DMSO (dimethyl sulfoxide) [ 33 , 34 , 35 ] to the reaction mix and the use of OSD (oligonucleotide strand displacement) probes [ 24 , 25 , 26 , 27 , 28 ], have been proven to improve LAMP accuracy. In particular, compartmentalization of the reaction through microfluidics [ 29 , 30 , 31 ] and emulsion [ 32 , 122 , 123 ] techniques have shown substantial success in improving accuracy by limiting the effects of contaminants. This has been applied to PCR reactions as well, most popularly through digital-droplet PCR (ddPCR), in which reactions are partitioned (using oil) into thousands of “droplets,” eliminating interference from reaction-inhibiting particles [ 124 ].…”

Contamination-resistant, rapid emulsion-based isothermal nucleic acid amplification with Mie-scatter inspired light scatter analysis for bacterial identification

“…This paper focuses on conducting LAMP reactions in a water–oil emulsion platform (emulsion LAMP, or eLAMP) in an attempt to lower the prevalence of non-specific amplification, while also showing reduced reaction times when compared to conventional methods. The mechanism in which we will monitor in real-time the effects of amplification is based on the interfacial changes of micron size emulsions due to amplicon adsorption, followed by emulsion destabilization 11 (Fig. 1 A).…”

Interfacial Effect-Based Quantification of Droplet Isothermal Nucleic Acid Amplification for Bacterial Infection

“…Similarly, due to increased interest in POC applications, digital LAMP (dLAMP) platforms have been developed 26–28 . However, none of these studies have actively utilized interfacial tension as a sensing mechanism for the amplification of target genes 29,30 . It is possible to relate this interfacial tension to molecular self-assembly at the interface (e.g.…”