Immobilized Polydiacetylene Lipid Vesicles on Polydimethylsiloxane Micropillars as a Surfactin-Based Label-Free Bacterial Sensor Platform

Abstract

Accurate detection and sensing of bacteria are becoming increasingly important not only in microbiology but in a variety of fields including medicine, food, public health, and environmental science. However, even new rapid methods are not convenient enough.Here, we describe a simple and efficient label-free bacterial detection system using the polydiacetylene (PDA) liposomes immobilized on the 3D polydimethylsiloxane (PDMS) micropillars. Our system utilizes the colorimetric response of amine functionalized PDA vesicles to surfactin, a bacterial cyclic lipopeptide commonly released by Gram-positive Bacillus species as an antibiotic. To improve the sensitivity of PDA vesicles to surfactin by increasing the number and surface area of immobilized vesicles, the PDA vesicles were immobilized on the micropillar structure to give a hierarchical 3D PDA vesicle structure. For the fabrication of the 3D micropillar structure, polydimethylsiloxane (PDMS) was used to overcome the limitations imposed by silicon-based fabrication. In contrast to the 2D-PDA-PDMS system, which could only hardly detect the presence of 500 µM surfactin, the 3D-PDA-PDMS system could efficiently detect the presence of 5 µM surfactin and the initial presence of 4 × 10 1 cells/ml of Bacillus subtilis NCIB3610, which actively produces surfactin. Furthermore, bacterial strains that are known to produce no surfactin, such as Staphylococcus aureus Newman, Escherichia coli DH5α, and Pseudomonas aeruginosa PA14 were not detected by our system suggesting that the 3D-PDA-PDMS system is highly specific to surfactin but not to other chemicals produced by bacteria. Taken together, our results suggest that the 3D-PDA-PDMS system can sensitively and selectively be used for the high throughput detection and screening of biotechnologically important surfactin-producing bacterial strains.

Naked-Eye Detection of Ethylene Using Thiol-Functionalized Polydiacetylene-Based Flexible Sensors

“…To specifically tune the response of PDA to a particular stimulating agent, the polymer chains are often functionalized to enable their interaction with the desired analyte molecules. The most widely used modification method applied to PDA is through the reaction between their carboxylic acid moiety and an activating agent such as N -hydroxysuccinimide/ethyl-(dimethylaminopropyl)­carbodiimide, − thionyl chloride, , and oxalyl chloride. , The modified PDA derivatives have been used in various sensing applications for the detection of solvents, ions, biomolecules, microorganisms, temperature, pH, and mechanical stress . PDA can also be used for the detection of various analytes such as NH 3 , CO 2 , HCl, and volatile organic compounds .…”

Optimizing Silanization to Functionalize Stainless Steel Wire: Towards Breast Cancer Stem Cell Isolation

“…In this work, we observed a decrease in the surface roughness after GA ( Figure 7 ) with lowered rms from 0.1 to 2 nm across the samples. After treating with GA, it is expected that the surface either retains the same rms as the silanized surface (0.18 nm) [ 49 ] or becomes smoother, as reported by two studies (from rms 0.830 µm to 0.524 µm in [ 50 ] and rms from 0.69 to 0.51 nm in [ 35 ]). Binding of GA was also confirmed by CV where after GA, treatment of the HT sample lowered the peak current and increased the peak-to-peak separation ( Figure 8 ).…”

Aerosol Jet® printing 3D capabilities for metal and polymeric inks

“…In particular, 3D periodic microstructures, such as arrays of pillars or lattice units, with well-defined geometrical characteristics (aspect ratio (AR), diameter, height, and inter-spacing), have been efficiently used for micro-electromechanical systems (MEMS), energy harvesting 3D micro-batteries, bioinspired architectures, micro-sensors (elec-trochemical sensing, micro-actuators), micro-optical devices, circuit packaging, etc [3][4][5]. In life science, 3D periodic microstructures have also been embedded in bacterial sensors, scaffold-based cell culture systems for guiding and cell growth, electrophysiological recording sensors, and microbial electrolytic cell [6][7][8].…”