Transport of Oligopeptide from Aqueous Phase to Span 80 Reverse Micelles in Microdroplet Array

Abstract

The partitioning of water and tetramethylrhodamine-conjugated-10-residue oligopeptides from the aqueous phase of microdroplets into Span 80 reverse micelles was observed by utilizing microdroplet arrays. Each peptide was dissolved in phosphate buffer saline, and initially encapsulated in arrayed droplets. An organic phase containing the reverse micelles was added to the microdroplets. Here, the hydration degree of the reverse micelle was adjusted by contact of the organic phase with a 1.0 M NaCl aqueous solution or with a phosphate buffer saline before combining it with the microdroplets. For micelles treated with a 1.0 M NaCl, significant water transport from the microdroplet to the micelle was observed, and peptide with low solubility in water was transported to the reverse micelles, while those with high solubility in water were not. For micelles treated with phosphate buffer saline, the water transport was minimal, and no significant peptide transport was observed. These results suggest that the partitioning of low-solubility oligopeptides requires accompanying water transport to the reverse micelle phase.

Nanoparticle Assembly at the Water–Oil Interface Induced by Spontaneous Emulsification for Microdroplet Immunoassay

“…Polydimethylsiloxane (PDMS) microfluidic devices with 210 μm wide and 80 μm deep square microwells on the ceiling of a 3 μm wide 80 μm deep microchannel (Figure ) were fabricated by soft lithography. A 700:100:5 mixture of PDMS, curing agents, and additive (501 W) was cured at 75 °C using a previously reported procedure . This additive was used to prevent the adsorption of proteins on the channel walls …”

“…A 700:100:5 mixture of PDMS, curing agents, and additive (501 W) was cured at 75 °C using a previously reported procedure. 8 This additive was used to prevent the adsorption of proteins on the channel walls. 25 Control of Water Activity in Span 80 Reverse Micelles.…”

“…We have previously reported the selective enrichment of microdroplet contents utilizing spontaneous nanodroplet formation, known as spontaneous emulsification. − Spontaneous emulsification is defined as emulsification without an external energy supply . When an aqueous microdroplet is set in an organic solution flow containing Span 80, a nonionic surfactant commonly used in droplet microfluidics, water partitions to the Span 80 reverse micelles, and nanometer-sized droplets are formed (Figure a) .…”

Kinetic description of water transport during spontaneous emulsification induced by Span 80

“…22,23 By utilizing the spontaneous emulsification of Span 80, we have previously developed microanalytical methods in micrometer-sized waterin-oil droplets (microdroplets). [6][7][8][9][10] In this method, the selective concentration enrichment of microdroplet contents was achieved based on the molecular transport, including water 23 and solutes, 8,24 to the Span 80 nanodroplet during spontaneous emulsification. As a result, various microdroplet manipulations such as protein crystallization 6 and immunoassay were demonstrated.…”

Spectrometric Analyses of Microplastics

“…Analytical scientists have continuously developed or applied novel microfluidic systems, paper-based analytical devises, and image processing tools. [35][36][37] The development of novel analytical methods and application to MPs analysis will be effective in gaining a deeper understanding of the impacts of MPs.…”