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Development of a liposome-based immunochromatographic strip assay for the detection of Salmonella.
Shukla, Shruti,Leem, Hyerim,Kim, Myunghee Springer-Verlag 2011 Analytical and bioanalytical chemistry Vol.401 No.8
<P>Salmonella species are ubiquitous human pathogens which pose a dangerous threat to the elderly and children worldwide. In this study, to develop a more efficient assay procedure for the rapid detection of Salmonella Typhimurium, an immunochromatographic strip assay was developed using immunoliposome (anti-Salmonella IgG-tagged) encapsulated with sulforhodamine B (SRB). The detection sensitivity of the developed immunochromatographic assay was compared with a commercial immunochromatographic test strip using colloidal gold nanoparticles. The liposomes were prepared through a reverse-phase evaporation method by using a lipid and phospholipid mixture and SRB, a fluorescence dye, which was encapsulated in the phospholipid bilayer. Furthermore, the outer surface of the SRB-encapsulated liposome was conjugated with antibody (affinity-purified polyclonal goat anti-Salmonella IgG) to form an immunoliposome (size, 223 nm), used as the analytical reagent in the developed immunoassay. For this strip assay, a plastic-backed nitrocellulose strip was immobilized with two antibody zones. The lower zone of the strip referred to Salmonella antigen capture zone (test line), while the other zone served as a positive control (control line). The lower zone was coated with affinity-purified polyclonal goat anti-Salmonella IgG, while the upper zone was coated with rabbit anti-goat IgG. During capillary migration of the wicking solution (diluted liposome and Salmonella culture, each 50 관l), Salmonella was captured with surface-bound immunoliposomes at the antigen capture zone, while the unbound liposomes migrated upward and bound to another zone. The color density of the antigen capture zone was directly proportional to the amount of S. Typhimurium in the test sample. As a result, the detection limit of the immunochromatographic strip assay developed in this study against S. Typhimurium was found to be 10(2) CFU/ml, which was significantly higher than the detection limit (10(7) CFU/ml) of the commercial immunochromatographic test strip assay.</P>
Shukla, Shruti,Kim, Myunghee 한국식품과학회 2016 Food Science and Biotechnology Vol.25 No.4
This study deals with understanding the effects of starter cultures on the safety aspects of soy sauce fermentation and their application to compensate undesirable changes occurring during fermentation processes. Various starter cultures of bacterial and fungal combinations with different microbial strains were used for the production of soy sauce samples under standardized fermentation/manufacturing conditions, and contents of biogenic amines (BAs) and aflatoxins were determined. Quantitative analysis of BAs and aflatoxins was performed using HPLC and immunoassay-based total aflatoxin detection kit, respectively. The amount of total BAs in all laboratory-made starter culture soy sauce samples was quantified in the range of 2.80-20.42 mg/L, which was within the limit of human consumption safety level. In addition, the level of total aflatoxin was under the limit (0.00 to $4.80{\mu}g/kg$), according to the standard parameters of food and agricultural organization (FAO) and world health organization (WHO).
Shukla, Shruti,Haldorai, Yuvaraj,Bajpai, Vivek K.,Rengaraj, Arunkumar,Hwang, Seung Kyu,Song, Xinjie,Kim, Myunghee,Huh, Yun Suk,Han, Young-Kyu Elsevier 2018 Biosensors & bioelectronics Vol.109 No.-
<P><B>Abstract</B></P> <P>A sensitive electrochemical immunosensing platform for the detection of <I>Cronobacter sakazakii</I> was developed using a graphene oxide/gold (GO/Au) composite. Transmission electron microscopy showed that the Au nanoparticles, with an average size of < 30 nm, were well dispersed on the GO surface. For the detection of <I>C. sakazakii</I>, a polyclonal anti-<I>C. sakazakii</I> antibody (IgG) was covalently immobilized to the Au nanoparticles on the surface of the GO/Au composite coated glassy carbon electrode (GCE). The electrochemical sensing performance of immunofunctionalized GCE was characterized by cyclic voltammetry and differential pulse voltammetry. Under optimized conditions, in pure culture there was a linear relationship between electrical signal and <I>C. sakazakii</I> levels over the range 2.0 × 10<SUP>2</SUP>–2.0 × 10<SUP>7</SUP> cfu/mL (R<SUP>2</SUP> = 0.999), with a detection limit of 2.0 × 10<SUP>1</SUP> cfu/mL. The total analytical time was 15 min per sample. The <I>C. sakazakii</I> electrochemical immunosensing assay was able to successfully detect 2.0 × 10<SUP>1</SUP> cfu/mL of <I>C. sakazakii</I> in artificially contaminated powdered infant formula without any enrichment or pre-enrichment steps. Furthermore, the recovery rates of the <I>C. sakazakii</I> electrochemical immunosensing assay following spiking of powdered infant formula with different concentrations of <I>C. sakazakii</I> (cfu/mL) were 82.58% at 2.0 × 10<SUP>1</SUP> cfu/mL, 84.86% at 2.0 × 10<SUP>2</SUP> cfu/mL, and 95.40% at 2.0 × 10<SUP>3</SUP> cfu/mL. The <I>C. sakazakii</I> electrochemical immunosensing assay had good selectivity, reproducibility, and reactivity compared with other <I>Cronobacter</I> spp. and/or pathogens belonging to other genera, indicating its significant potential in the clinical diagnosis of <I>C. sakazakii</I>.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Development of a GO/Au nanocomposite-based electrochemical immunosensing for <I>Cronobacter sakazakii</I> detection. </LI> <LI> The developed assay detected 2.0 × 10<SUP>1</SUP> cfu/mL of <I>C. sakazakii</I> in pure culture as well as in infant formula powder. </LI> <LI> Developed assay required a total analytical performance time of 15 min per sample. </LI> <LI> The assay facilitated sensitive, efficient, and rapid detection of <I>C. sakazakii</I> without any interfering factor. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Shukla, Shruti,Park, Juyeon,Park, Jung Hyun,Lee, Jong Suk,Kim, Myunghee Springer-Verlag 2018 Journal of food science and technology Vol.55 No.2
<P>Lotus (Nelumbo nucifera) root has been used as an edible vegetable in East Asia for thousands of years. The present research was aimed to explore the physicochemical, nutritional and microbiological safety of lotus root fermented sugar syrup as a fermented food supplement or condiment for human health benefits. In this study, the physicochemical, nutritional and microbiological safety properties of lotus root syrup fermented with 57A degrees Brix brown sugar at different time periods until 6 months (180 days) was investigated. There was a significant improvement as compared to 57A degrees Brix brown sugar broth (as a control) in the total acceptability and physicochemical properties of lotus root sugar syrup samples such as pH and color improvement. The red color values of 180 days lotus root fermented sugar syrup samples were significantly enhanced (6.85 +/- 0.58) when compared with the control (0.20 +/- 0.15). In addition, the total protein content was increased from 8.27 +/- 0.86 to 392.33 +/- 7.19 mu g/mL, along with the increase in fermentation time reaching to the level of consumption acceptability. All the lotus root fermented sugar syrup samples were subjected to microbiological analysis. It was found that the coliform, Bacillus cereus, Escherichia coli, Salmonella and Staphylococcus aureus counts were not detected in majority of the samples, confirming the high degree of hygiene processing of lotus root fermented sugar syrup samples for its use as a food supplement or condiment.</P>
김수지,( Shruti Shukla ),( Vivek K. Bajpai ),전태준 ( Imran Khan ),이은선,오미화,허윤석,한영규 한국공업화학회 2019 한국공업화학회 연구논문 초록집 Vol.2019 No.0
In this research, we synthesized a reduced graphene oxide/tin oxide (rGO/SnO<sub>2</sub>) composite for the electrochemical detection of fungal contaminant, patulin (PAT). The resulting rGO/SnO<sub>2</sub> composite exhibited promising electrochemical properties with outstanding performance to detect PAT levels in contaminated apple juice samples. The differential pulse voltammetric response of the rGO/SnO<sub>2</sub> composite electrode exhibited a linear relationship with PAT concentration in the 50-600 nM range and had a lower detection limit of 0.17nM. The sensor electrode exhibited high sensitivity, reliable reproducibility, and good selectivity. We found that the electrochemical sensor had ability to rapidly detect PAT in apple juice samples without the need of extraction or clean-up steps and achieved a higher recovery rate (74.33±0.70 to 99.26±0.70%) within a short-time analysis than did by the HPLC (61.97±1.78 to 84.31±1.96%), thus illustrating its feasibility for agricultural and food safety industries.
오서영,( Shruti Shukla ),( Vivek K. Bajpai ),( Imran Khan ),전태준,이은선,오미화,한영규,허윤석 한국공업화학회 2019 한국공업화학회 연구논문 초록집 Vol.2019 No.0
Histamine as neurotransmitter, plays an important role in regulating the biological circadian rhythm and wakefulness in human health. Liposome-based multiplexed dual-layered assembled lipo-immunonanofluorophore biosensing was developed as a suitable biosensor device, which integrates immuno-liposomes in dual layered sandwich immunoassay format. Method 1 based on a dual-layered single wash procedure, which had a detection limit of 10 ppb and Method 2 was based on a dual layered one-by-one wash procedure and had a detection limit of 2-3 ppb that required 2 h 30 min to perform. Method 2 was chosen for further validation. The feasibility of developed multiplexed sensing was tested in histamine contaminated fresh mackerel fish, and canned fish (tuna), which showed a similar detection range but with low amplified fluorescence signal intensities and sufficient levels of histamine recovery from fresh mackerel (73.5-99.98%), canned tuna (79.08-103.74%).