Herein, we demonstrate a simple and inexpensive one-pot green synthesis of silver nanoparticles (Ag-NPs) functionalised with a combination of banana peel (Musa paradisiaca) and grape (Vitis vinifera) fruit extracts. T...Herein, we demonstrate a simple and inexpensive one-pot green synthesis of silver nanoparticles (Ag-NPs) functionalised with a combination of banana peel (Musa paradisiaca) and grape (Vitis vinifera) fruit extracts. The reaction mixture of aqueous silver nitrate, banana peel and grapefruit extracts revealed a dark brown colour after a reaction time of 18 minutes, which indicates the presence and the successful synthesis of silver nanoparticles. The optical and structural properties of the green synthesised nanoparticles were analysed using UV-Visible spectroscopy (UV-Vis) which confirmed an absorption band at 440 nm. The polydispersity nature and the AgNPs sizes of 30 nm were revealed using small angle X-ray scattering (SAXS) and high-resolution transmission electron microscopy (HR-TEM) techniques. Fourier transform infrared spectroscopy (FT-IR) studies revealed the structure of these nanoparticles which included carbonyl groups, primary amine groups, OH groups and other stabilizing functional groups characteristic of the properties of combined extracts. A simple, quick, less time-consuming surface plasmon resonance (SPR) and electrochemical method in the form of optical and electrochemical sensors have been developed for the detection of Escherichia coli 0157:H7. The obtained limit of detection (LOD) values for SPR and GBPE-Ag-NPs/GCE-based sensor systems were found to be 1 × 102 CFU/mL and 3.5 × 101 CFU/mL, respectively. The obtained values fall within the range for E. coli 0157:H7 in seawater.展开更多
Produce-associated food-borne outbreaks have been increasingly implicated as the significant proportion of the annual incidence of food-borne ilness worldwide.The objectives of this study were to determine the concent...Produce-associated food-borne outbreaks have been increasingly implicated as the significant proportion of the annual incidence of food-borne ilness worldwide.The objectives of this study were to determine the concentrations of indicator bacteria and the presence of Salmonella spp.Shigella spp..Escherichia coli(E.coln 0157:H7,and Listeria monocytogenes(L.monocytogenes),and to characterize predictors associated with Salmonella contamination of retail produce from fresh markets and supermarkets in Bangkok,Thailand.A total of 503 samples were col-lected during May 2018 and February 2019,comprised of sweet basil,spring onion,coriander,cabbage,lettuce,cucumber,and tomato,with conventional items from fresh open-air markets(n=167),conventional items from supermarkets(n=168),and organic items from supermarkets(n=168).The overall prevalence in these 503 items for fecal coliforms and E.coli was 84.3%and 71.4%,with mean concentrations(±standard deviation)of fecal coliforms and E.coli being(3.0×10^(5)±1.3×10^(5))most probable number(MPN)/g and(1.8×10^(5)±1.1×10^(5))MPN/g,respectively.The concentrations of fecal coliforms and E.coli were higher in produce sampled from fresh open-air markets than produce from supermarkets;simi-larly,these bacterial indicators were higher from produce grown under conventional methods than certified organic produce.The prevalence of Salmonella and Shigella was 4.8%and 0.4%,respectively,but no positives were found for E.coli 0157:H7 and L.monocytogenes.The predom-inant Salmonella serovar was Stanley(30.8%).Based on logistic regression,the odds of Salmonella contamination were significantly(P<0.05)higher during the rainy versus dry season,produce grown using conventional versus organic agriculture,sweet basil versus other commodities,and using ice tank versus dry refrigeration for overnight retail storage.This study indicated that fruits and vegetables are important sources of microbial contamination.Hence,monitoring and surveillance of pathogen contamination to produce is needed to strengthen food safety.展开更多
文摘Herein, we demonstrate a simple and inexpensive one-pot green synthesis of silver nanoparticles (Ag-NPs) functionalised with a combination of banana peel (Musa paradisiaca) and grape (Vitis vinifera) fruit extracts. The reaction mixture of aqueous silver nitrate, banana peel and grapefruit extracts revealed a dark brown colour after a reaction time of 18 minutes, which indicates the presence and the successful synthesis of silver nanoparticles. The optical and structural properties of the green synthesised nanoparticles were analysed using UV-Visible spectroscopy (UV-Vis) which confirmed an absorption band at 440 nm. The polydispersity nature and the AgNPs sizes of 30 nm were revealed using small angle X-ray scattering (SAXS) and high-resolution transmission electron microscopy (HR-TEM) techniques. Fourier transform infrared spectroscopy (FT-IR) studies revealed the structure of these nanoparticles which included carbonyl groups, primary amine groups, OH groups and other stabilizing functional groups characteristic of the properties of combined extracts. A simple, quick, less time-consuming surface plasmon resonance (SPR) and electrochemical method in the form of optical and electrochemical sensors have been developed for the detection of Escherichia coli 0157:H7. The obtained limit of detection (LOD) values for SPR and GBPE-Ag-NPs/GCE-based sensor systems were found to be 1 × 102 CFU/mL and 3.5 × 101 CFU/mL, respectively. The obtained values fall within the range for E. coli 0157:H7 in seawater.
基金the University of California Davis(A18-1020-S001),USAthe Chulalongkorn University Graduate Scholarship to Commemorate the 72nd Anniversary of His Majesty King Bhumibol Adulyadej(Thailand)to Jutanat Srisamran.
文摘Produce-associated food-borne outbreaks have been increasingly implicated as the significant proportion of the annual incidence of food-borne ilness worldwide.The objectives of this study were to determine the concentrations of indicator bacteria and the presence of Salmonella spp.Shigella spp..Escherichia coli(E.coln 0157:H7,and Listeria monocytogenes(L.monocytogenes),and to characterize predictors associated with Salmonella contamination of retail produce from fresh markets and supermarkets in Bangkok,Thailand.A total of 503 samples were col-lected during May 2018 and February 2019,comprised of sweet basil,spring onion,coriander,cabbage,lettuce,cucumber,and tomato,with conventional items from fresh open-air markets(n=167),conventional items from supermarkets(n=168),and organic items from supermarkets(n=168).The overall prevalence in these 503 items for fecal coliforms and E.coli was 84.3%and 71.4%,with mean concentrations(±standard deviation)of fecal coliforms and E.coli being(3.0×10^(5)±1.3×10^(5))most probable number(MPN)/g and(1.8×10^(5)±1.1×10^(5))MPN/g,respectively.The concentrations of fecal coliforms and E.coli were higher in produce sampled from fresh open-air markets than produce from supermarkets;simi-larly,these bacterial indicators were higher from produce grown under conventional methods than certified organic produce.The prevalence of Salmonella and Shigella was 4.8%and 0.4%,respectively,but no positives were found for E.coli 0157:H7 and L.monocytogenes.The predom-inant Salmonella serovar was Stanley(30.8%).Based on logistic regression,the odds of Salmonella contamination were significantly(P<0.05)higher during the rainy versus dry season,produce grown using conventional versus organic agriculture,sweet basil versus other commodities,and using ice tank versus dry refrigeration for overnight retail storage.This study indicated that fruits and vegetables are important sources of microbial contamination.Hence,monitoring and surveillance of pathogen contamination to produce is needed to strengthen food safety.
