Aptasensors for rapid detection of Escherichia coli O157:H7 and Salmonella typhimurium

Abstract

Herein we reported the development of aptamer-based biosensors (aptasensors) based on label-free aptamers and gold nanoparticles (AuNPs) for detection of Escherichia coli (E. coli) O157:H7 and Salmonella typhimurium. Target bacteria binding aptamers are adsorbed on the surface of unmodified AuNPs to capture target bacteria, and the detection was accomplished by target bacteria-induced aggregation of the aptasensor which is associated as red-to-purple color change upon high-salt conditions. By employing anti-E. coli O157:H7 aptamer and anti-S. typhimurium aptamer, we developed a convenient and rapid approach that could selectively detect bacteria without specialized instrumentation and pretreatment steps such as cell lysis. The aptasensor could detect as low as 105colony-forming units (CFU)/ml target bacteria within 20 min or less and its specificity was 100%. This novel method has a great potential application in rapid detection of bacteria in the near future.

Chemiluminescent aptasensor capable of rapidly quantifying Escherichia Coli O157:H7

“…Thus, only a very limited amount of the enormous domestic and imported foods that are released in the food market are being inspected using the conventional analytical system [2]. Recently, various aptamers using single strand DNA or RNA have been developed to capture foodborne pathogens in a sample [3][4][5][6][7]. Also, new analytical methods capable of rapidly quantifying trace levels of foodborne pathogens using aptasensors with chemiluminescence [8], colorimeter [7,9], electrochemical [9], or fluorescence [10] detection have been reported.…”

“…Recently, various aptamers using single strand DNA or RNA have been developed to capture foodborne pathogens in a sample [3][4][5][6][7]. Also, new analytical methods capable of rapidly quantifying trace levels of foodborne pathogens using aptasensors with chemiluminescence [8], colorimeter [7,9], electrochemical [9], or fluorescence [10] detection have been reported. Using aptasensors, it was possible to detect foodborne pathogens without complicated and tedious procedures such as multiple incubations and washings [8].…”

“…DNA aptamer capable of rapidly binding E. Coli O157:H7 in a sample with excellent specificity and selectivity contains multiple guanines [7]. Thus, it is possible to develop a novel analytical method capable of rapidly quantifying E. Coli O157:H7 using E. Coli O157:H7 aptamer-conjugated fluorescent dye and guanine chemiluminescence detection.…”

Developments in nanoparticles for use in biosensors to assess food safety and quality

“…For example, a sensor for E. coli O157:H7 and Salmonella has been reported based on the immobilization of aptamers onto the surface of gold nanoparticles ( Pieta et al, 2013 andWu et al, 2012). In one example, upon binding of the pathogen target there is a visible change of the nanobeads from red to blue.…”

Fluorometric sensing of endotoxin based on aggregation of CTAB capped gold nanospheres

“…The wide usage of GNPs was mainly due to the simple preparation method and functionalization of the nanoparticle with antibodies, aptamers or chemicals having exceptional spectral features and good stability characteristics. Detection of E. coli was colorimetric detected using gold nanoparticles functionalized with borohydride [17], mercaptoethylamine [18], aptamers [19], antibodies [20] and cysteine [21] by observing the change in the surface plasmon resonance band. Rod-shaped gold nanoparticles were also synthesized and functionalized with 11-Mercaptoundecanoic acid and Cystamine dihydrochloride to detect efficiently E. coli bacteria [22,23].…”