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Enhanced detection sensitivity of Escherichia coli O157:H7 using surface-modified gold nanorods.

Ramasamy M, Yi DK, An SS - Int J Nanomedicine (2015)

Bottom Line: Endogenous membrane peroxidase, an enzyme present on the surface of O157, was used for the colorimetric detection of bacteria by catalytic oxidation of the peroxidase substrate.In this study, we have analyzed the impact of the synthesized bare gold nanorods (AuNRs) and silica-coated AuNRs on the growth of E. coli O157.This result can be particularly important for the enzymatic analysis of surface treated AuNRs in various microbiological applicants.

View Article: PubMed Central - PubMed

Affiliation: School of Chemical Engineering, Yeungnam University, Gyeongsan, Republic of Korea.

ABSTRACT
Escherichia coli O157:H7 (O157) is a Gram negative and highly virulent bacteria found in food and water sources, and is a leading cause of chronic diseases worldwide. Diagnosis and prevention from the infection require simple and rapid analysis methods for the detection of pathogens, including O157. Endogenous membrane peroxidase, an enzyme present on the surface of O157, was used for the colorimetric detection of bacteria by catalytic oxidation of the peroxidase substrate. In this study, we have analyzed the impact of the synthesized bare gold nanorods (AuNRs) and silica-coated AuNRs on the growth of E. coli O157. Along with the membrane peroxidase activity of O157, other bacteria strains were analyzed. Different concentrations of nanorods were used to analyze the growth responses, enzymatic changes, and morphological alterations of bacteria by measuring optical density, 3,3',5,5'-tetramethylbenzidine assay, flow cytometry analysis, and microscopy studies. The results revealed that O157 showed higher and continuous membrane peroxidase activity than other bacteria. Furthermore, O157 treated with bare AuNRs showed a decreased growth rate in comparison with the bacteria with surface modified AuNRs. Interestingly, silica-coated AuNRs favored the growth of bacteria and also increased membrane peroxidase activity. This result can be particularly important for the enzymatic analysis of surface treated AuNRs in various microbiological applicants.

No MeSH data available.


Related in: MedlinePlus

Morphological analyses of E. coli O157 after TMB assay using FE-SEM.Notes: Panels (Ai and Aii) represent the untreated control bacteria and its magnified image. (Bi) AuNRs-treated bacteria, (Bii) disoriented cells after treatment. (Ci) Enhanced bacteria growth toward Si-AuNRs, (Cii) specific attachment of Si-AuNRs with E. coli cells by maintaining complete cell morphology.Abbreviations: FE-SEM, field emission scanning electron microscopy; TMB, 3,3′,5,5′-tetramethylbenzidine; E. coli O157, Escherichia coli O157; AuNRs, gold nanorods; Si-AuNRs, silica-coated gold nanorods.
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f8-ijn-10-179: Morphological analyses of E. coli O157 after TMB assay using FE-SEM.Notes: Panels (Ai and Aii) represent the untreated control bacteria and its magnified image. (Bi) AuNRs-treated bacteria, (Bii) disoriented cells after treatment. (Ci) Enhanced bacteria growth toward Si-AuNRs, (Cii) specific attachment of Si-AuNRs with E. coli cells by maintaining complete cell morphology.Abbreviations: FE-SEM, field emission scanning electron microscopy; TMB, 3,3′,5,5′-tetramethylbenzidine; E. coli O157, Escherichia coli O157; AuNRs, gold nanorods; Si-AuNRs, silica-coated gold nanorods.

Mentions: The morphological changes of the bacteria in the presence of nanorods were analyzed using FE-SEM study (Figure 8). The TMB assayed, bare AuNRs-treated bacteria showed disintegrated cell structure in Figure 8Bi compared to intact, proximally populated control cells (Figure 8Ai and Aii). More precisely, the enlarged view clearly depicts the ruptured, irrecoverable, disordered population in bare AuNRs-treated bacteria cells (AuNRs as white dots; Figure 8Bii). On the other hand, Si-AuNRs-treated bacteria showed enhanced growth with the formation of new populations as shown in Figure 8Ci. Attachment of Si-AuNRs on the surface of bacteria with enhanced formation of new colony was observed (Figure 8Cii). These observations corroborate the significant impact of the uncoated and coated nanorods on bacterial growth and enzymatic activity.


Enhanced detection sensitivity of Escherichia coli O157:H7 using surface-modified gold nanorods.

Ramasamy M, Yi DK, An SS - Int J Nanomedicine (2015)

Morphological analyses of E. coli O157 after TMB assay using FE-SEM.Notes: Panels (Ai and Aii) represent the untreated control bacteria and its magnified image. (Bi) AuNRs-treated bacteria, (Bii) disoriented cells after treatment. (Ci) Enhanced bacteria growth toward Si-AuNRs, (Cii) specific attachment of Si-AuNRs with E. coli cells by maintaining complete cell morphology.Abbreviations: FE-SEM, field emission scanning electron microscopy; TMB, 3,3′,5,5′-tetramethylbenzidine; E. coli O157, Escherichia coli O157; AuNRs, gold nanorods; Si-AuNRs, silica-coated gold nanorods.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4556300&req=5

f8-ijn-10-179: Morphological analyses of E. coli O157 after TMB assay using FE-SEM.Notes: Panels (Ai and Aii) represent the untreated control bacteria and its magnified image. (Bi) AuNRs-treated bacteria, (Bii) disoriented cells after treatment. (Ci) Enhanced bacteria growth toward Si-AuNRs, (Cii) specific attachment of Si-AuNRs with E. coli cells by maintaining complete cell morphology.Abbreviations: FE-SEM, field emission scanning electron microscopy; TMB, 3,3′,5,5′-tetramethylbenzidine; E. coli O157, Escherichia coli O157; AuNRs, gold nanorods; Si-AuNRs, silica-coated gold nanorods.
Mentions: The morphological changes of the bacteria in the presence of nanorods were analyzed using FE-SEM study (Figure 8). The TMB assayed, bare AuNRs-treated bacteria showed disintegrated cell structure in Figure 8Bi compared to intact, proximally populated control cells (Figure 8Ai and Aii). More precisely, the enlarged view clearly depicts the ruptured, irrecoverable, disordered population in bare AuNRs-treated bacteria cells (AuNRs as white dots; Figure 8Bii). On the other hand, Si-AuNRs-treated bacteria showed enhanced growth with the formation of new populations as shown in Figure 8Ci. Attachment of Si-AuNRs on the surface of bacteria with enhanced formation of new colony was observed (Figure 8Cii). These observations corroborate the significant impact of the uncoated and coated nanorods on bacterial growth and enzymatic activity.

Bottom Line: Endogenous membrane peroxidase, an enzyme present on the surface of O157, was used for the colorimetric detection of bacteria by catalytic oxidation of the peroxidase substrate.In this study, we have analyzed the impact of the synthesized bare gold nanorods (AuNRs) and silica-coated AuNRs on the growth of E. coli O157.This result can be particularly important for the enzymatic analysis of surface treated AuNRs in various microbiological applicants.

View Article: PubMed Central - PubMed

Affiliation: School of Chemical Engineering, Yeungnam University, Gyeongsan, Republic of Korea.

ABSTRACT
Escherichia coli O157:H7 (O157) is a Gram negative and highly virulent bacteria found in food and water sources, and is a leading cause of chronic diseases worldwide. Diagnosis and prevention from the infection require simple and rapid analysis methods for the detection of pathogens, including O157. Endogenous membrane peroxidase, an enzyme present on the surface of O157, was used for the colorimetric detection of bacteria by catalytic oxidation of the peroxidase substrate. In this study, we have analyzed the impact of the synthesized bare gold nanorods (AuNRs) and silica-coated AuNRs on the growth of E. coli O157. Along with the membrane peroxidase activity of O157, other bacteria strains were analyzed. Different concentrations of nanorods were used to analyze the growth responses, enzymatic changes, and morphological alterations of bacteria by measuring optical density, 3,3',5,5'-tetramethylbenzidine assay, flow cytometry analysis, and microscopy studies. The results revealed that O157 showed higher and continuous membrane peroxidase activity than other bacteria. Furthermore, O157 treated with bare AuNRs showed a decreased growth rate in comparison with the bacteria with surface modified AuNRs. Interestingly, silica-coated AuNRs favored the growth of bacteria and also increased membrane peroxidase activity. This result can be particularly important for the enzymatic analysis of surface treated AuNRs in various microbiological applicants.

No MeSH data available.


Related in: MedlinePlus