A composite prepared from carboxymethyl chitosan and aptamer-modified gold nanoparticles for the colorimetric determination of Salmonella typhimurium

Functionalized Inorganic Nanoparticles for the Detection of Food and Waterborne Bacterial Pathogens

“…Short shelf-life and easy contamination is mostly common in this product. Studies evaluating the detection of pathogens in spiked milk using biofunctionalized inorganic nanoparticles has been reported [68,76,91,95,100,101,106,117]. Investigation by Ma et al [63] on the colorimetric detection of S. typhi using aptamer modified-AuNPs had 96.4% recoveries similar to those obtained using the plate counting methods (104.3%).…”

“…It was found to increase electron transfer, electrochemical signal and ascertain detection within a short period (20-60 minutes). Few studies evaluated the bi-functional approaches of aptamer with other bio-receptors such as 4-mercaptobenzoic acid (4-MBA) [66], oligonucleotide probe [67], chitosan [68], 4-MBA and citrate [69]. Each complementing bio-receptors reported showed fast, sensitive, specificity and accurate SERS based sensors towards the detection of pathogens in samples.…”

Recent Advances in Aptamer Sensors

“…The system showed a linear relationship for S. typhimurium from 3.3 × 10 1 to 3.3 × 10 6 CFU/mL, with LODs of 33 and 95 CFU/mL for detection by the naked eye in pure culture and milk, respectively ( Table 1 ) [ 87 ]. S. typhimurium bacteria have also been detected via AuNP aggregation through competitive aptamer–target binding under the influence of salts, as inducers of aggregation, with a linear range of 100 to 10 9 CFU/mL and LOD of 16 CFU/mL, as reported by Jiecan [ 88 ]. The AuNP salt-induced aggregation mechanism was determined in an assay for aflatoxin M 1 (AFM1) as described by Seyed et al [ 89 ].…”

“…Recently, Zong et al, and Liu et al [91,92] proposed a study on the competitive binding affinities of both the aptamer and target toward the AuNPs and the effect of this binding on the sensing strategy based on salt-induced aggregation, as displayed in Figure As previously discussed, several colorimetric aptasensors were developed based on AuNP-induced aggregation with different targets such as malathion, Cd 2+ , Salmonella typhimurium, and AFB1, changing the specific aptamer functionalized with the AuNPs [85][86][87][88]90]. The question is what the role of these targets and others in the stability and instability of AuNPs in solution is, and if this could influence the salt-induced AuNP aggregation or not, affecting the reliability of the proposed strategies.…”

“…Similarly, a colorimetric aptasensor based on the aggregation of AuNPs as a signal transducer using cationic perylene probe as gold aggregating agent (CPP) was also provided by Lerdsrias et al for assaying aflatoxin B1 (AFB1), with a LOD of 0.18 ng/mL [90], as shown in Figure 2A. As previously discussed, several colorimetric aptasensors were developed based on AuNP-induced aggregation with different targets such as malathion, Cd 2+ , Salmonella typhimurium, and AFB1, changing the specific aptamer functionalized with the AuNPs [85][86][87][88]90]. The question is what the role of these targets and others in the stability and instability of AuNPs in solution is, and if this could influence the salt-induced AuNP aggregation or not, affecting the reliability of the proposed strategies.…”