Polydiacetylene Nanofiber Composites as a Colorimetric Sensor Responding To Escherichia coli and pH

Abstract

Polydiacetylenes (PDAs) are conjugative polymers that demonstrate color changes as a response to an external stimulus. In this study, 10,12-pentacosadiynoic acid (PCDA) was mixed with a supporting polymer including poly(ethylene oxide) (PEO) and polyurethane (PU), and the mixture solution was electrospun to construct fiber composites. The electrospun fibers were then photopolymerized using UV irradiation to produce PEO–PDA and PU–PDA nanofiber mats with a fiber diameter ranging from 130 nm to 2.5 μm. The morphologies of both PEO–PDA and PU–PDA nanofibers were dependent on electrospinning parameters such as the ratio of PCDA to PEO or PCDA to PU and the total polymer concentrations. Scanning electron microscopy images showed beaded fibers of PEO–PDA and PU–PDA at 2 and 18 w/v % concentrations, respectively. Smooth fibers were found when the solvent concentration was increased to 3.75 w/v % in PEO–PDA and 25 w/v % in PU–PDA fibers. Both PEO–PDA and PU–PDA nanofiber composites demonstrated excellent colorimetric responses to the presence of Escherichia coli ATCC25922 bacterial cells and the changes in pH as external stimuli. The nanofibers underwent a rapid colorimetric response when exposed directly to E. coli ATCC25922 grown on Luria–Bertani agar. The comparison between the PEO–PDA and PU–PDA suggested that the combination of PEO and PDA is favorable because it provides a sensitive response to the presence of E. coli. The results were compared with samples of a PDA polymer in the absence of a matrix polymer. The colorimetric response was similar when the PDA polymer and the PDA nanofiber composites were exposed to pH changes, and the color change was found to occur at pH 10 and enhanced at pH 11–13. The PDA-containing nanofiber composites showed stronger colorimetric responses than those of the PDA polymer only, suggesting their potential as biosensors and chemosensors.

The effect of 10,12-pentacosadiynoic acid on the morphology and characteristics of electrospun PDA/PU nanofibers

“…Since the formation of the beads is due to polymer entanglement insufficient at low concentrations, there is a critical concentration that allows sufficient entanglement of the polymer chains to form continuous fibers. As the amount of PCDA added increases, there appears to be a larger attractive force between PCDA monomers with self-assembled structure than PCDA and PU matrix, leading to a higher critical concentration allowing polymer chain entanglement (Alam et al 2016;Yapor et al 2017). That is, as the amount of PCDA increases, the hydrogen-bonding of the carboxylic headgroups of the polymerized PCDA increases.…”

“…There have been recent reports that indicate that the performances of electrospun nanofibers can be improved by adding the new functional materials (Kim and Lee 2018;Lee et al 2017Lee et al , 2018. In addition, studies on the feasibility of using electrospun nanofibers as sensors have been made by varying the mixing ratio of PCDA based on polymer (Alam et al 2016;Yapor et al 2017). In the previous study Yapor et al (2017), limited the mixing ratio of PCDA and concentrations of electrospinning solutions to two methods, using PU and PEO as polymers.…”

“…In addition, studies on the feasibility of using electrospun nanofibers as sensors have been made by varying the mixing ratio of PCDA based on polymer (Alam et al 2016;Yapor et al 2017). In the previous study Yapor et al (2017), limited the mixing ratio of PCDA and concentrations of electrospinning solutions to two methods, using PU and PEO as polymers. Alam et al (2016) extended the concentration of the PEO spinning solution and the mixing ratio of the PCDA into three methods, and examined the effect of the concentration of the spinning solution and the mixing ratio of the PCDA on the size and surface roughness of the nanofibers in detail.…”

Study on microstructure and mechanical properties of polydiacetylene composite biosensors

“…1 The main purposes of the use of wound dressings are to remove exudate and to protect from outside contamination with pathogenic bacteria, as well as against dehydration. 4 Biosensors are the devices containing a biological recognition component that can trigger a response signal to pathogens, virus, and other biological stimuli. They keep the wound moist and protect from pathogenic bacteria.…”

Sensors from Electrospun Nanostructures

“…Colorimetric sensors based on nanofibres electrospun from a mixture of 10, 12-pentacosadiynoic acid and poly (ethylene oxide) and polyurethane can be used to detect Escherichia coli [73].…”