title: Plasmonic-based colorimetric and spectroscopic discrimination of acetic and butyric acids produced by different types of Escherichia coli through the different assembly structures formation of gold nanoparticles.
abstract: We present a plasmonic-based strategy for the colourimetric and spectroscopic differentiation of various organic acids produced by bacteria. The strategy is based on our discovery that particular concentrations of dl-lactic, acetic, and butyric acids induce different assembly structures, colours, and optical spectra of gold nanoparticles. We selected wild-type (K-12 W3110) and genetically-engineered (JHL61) Escherichia coli (E. coli) that are known to primarily produce acetic and butyric acid, respectively. Different assembly structures and optical properties of gold nanoparticles were observed when different organic acids, obtained after the removal of acid-producing bacteria, were mixed with gold nanoparticles. Moreover, at moderate cell concentrations of K-12 W3110 E. coli, which produce sufficient amounts of acetic acid to induce the assembly of gold nanoparticles, a direct estimate of the number of bacteria was possible based on time-course colour change observations of gold nanoparticle aqueous suspensions. The plasmonic-based colourimetric and spectroscopic methods described here may enable onsite testing for the identification of organic acids produced by bacteria and the estimation of bacterial numbers, which have applications in health and environmental sciences.
authors: Department of Chemical Engineering, Hanyang University, Seoul 04763, South Korea.
authors: Ju A
authors: JA
authors: La
authors: Department of Chemical Engineering, Hanyang University, Seoul 04763, South Korea.
authors: Sora
authors: S
authors: Lim
authors: Department of Chemical Engineering, Hanyang University, Seoul 04763, South Korea.
authors: Hyo Jeong
authors: HJ
authors: Park
authors: Department of Chemical and Biological Engineering, Korea University, Seoul 02841, South Korea.
authors: Min-Ji
authors: MJ
authors: Heo
authors: Department of Chemical Engineering, Hanyang University, Seoul 04763, South Korea.
authors: Byoung-In
authors: BI
authors: Sang
authors: Department of Chemical and Biological Engineering, Korea University, Seoul 02841, South Korea.
authors: Min-Kyu
authors: MK
authors: Oh
authors: Department of Chemical Engineering, Hanyang University, Seoul 04763, South Korea. Electronic address: enjoe@hanyang.ac.kr.
authors: Eun Chul
authors: EC
authors: Cho
mesh_terms: D000085:Acetates / Q000032:analysis / Q000378:metabolism*; D002087:Butyrates / Q000032:analysis / Q000378:metabolism*; D003124:Colorimetry; D004926:Escherichia coli / Q000378:metabolism*; D005818:Genetic Engineering; D006046:Gold / Q000737:chemistry / Q000378:metabolism*; D019344:Lactic Acid / Q000032:analysis / Q000096:biosynthesis*; D053768:Metal Nanoparticles / Q000737:chemistry*; D010781:Photography; D013056:Spectrophotometry, Ultraviolet
chemical_list: D000085:Acetates; D002087:Butyrates; D019344:Lactic Acid; D006046:Gold
keywords: Assembly of gold nanoparticles; Bacteria; Colorimetric discrimination and detection; Gold nanoparticles; Organic acids