scholarly journals Direct dilution of cell aliquot for high temporal resolution bacterial cell surface charge measurement

2017 ◽  
Author(s):  
Wenfa Ng
Keyword(s):  
Cell Surface ◽  
Sample Preparation ◽  
Surface Charge ◽  
Temporal Resolution ◽  
Gold Standard ◽  
Preparation Technique ◽  
Dilution Ratio ◽  
Error Type ◽  
Gold Standard Method ◽  
Charge Measurement

Bacteria surface charge mediates important cell-environment and microbe-host interactions, and its accurate and precise measurement by microelectrophoresis requires removing metabolites adhered to the cell surface, where repeated centrifugation and washing by buffers is the gold standard method for sample preparation. Unfortunately, the need for time consuming centrifugation limits the temporal resolution of sampling and profiling of experiment system dynamics; especially for samples requiring immediate treatment after sampling. Herein, the feasibility of diluting cell aliquots with buffer as a single step sample preparation technique for surface charge measurement was investigated by characterizing the effects of dilution ratio, cation type, and buffer conductivity on measuring surface charge of Escherichia coli DH5α (ATCC 53868) grown in LB Lennox medium. Results indicated that dilution ratio was critical to accurate surface charge measurement since poor signal-to-noise ratio in high or low cell concentration samples generated substantial error. Type of buffer cation was also important since putative binding of high affinity cations to the negatively-charged cell surface underestimated surface charge. Finally, high conductivity buffers enabled greater removal of adsorbed metabolites through increased charge screening; however, a broader statistical distribution of measured surface charge and less accurate data were also observed. At extreme conductivity values, measured surface charge exhibited multi-modal distribution; due probably to removal of both intrinsic cell surface ions and exogenous adsorbed metabolites, and called into question the accuracy of data. Altogether, one step dilution of cell aliquot with deionized water reliably reproduced E. coli surface charge values obtained using the gold standard approach. But, since the ensemble of secreted metabolites is bacteria and medium specific, distinct diluent and experimental parameters exist for each system. The described methodology may find use in preparing samples for cell surface characterization studies, where it would help reduce sample preparation time, and thus, improve temporal resolution at which scientific questions can be probed and answered.

scholarly journals Direct dilution of cell aliquot for high temporal resolution bacterial cell surface charge measurement

2017 ◽  
Author(s):  
Wenfa Ng
Keyword(s):  
Cell Surface ◽  
Sample Preparation ◽  
Surface Charge ◽  
Temporal Resolution ◽  
Gold Standard ◽  
Preparation Technique ◽  
Dilution Ratio ◽  
Error Type ◽  
Gold Standard Method ◽  
Charge Measurement

Bacteria surface charge mediates important cell-environment and microbe-host interactions, and its accurate and precise measurement by microelectrophoresis requires removing metabolites adhered to the cell surface, where repeated centrifugation and washing by buffers is the gold standard method for sample preparation. Unfortunately, the need for time consuming centrifugation limits the temporal resolution of sampling and profiling of experiment system dynamics; especially for samples requiring immediate treatment after sampling. Herein, the feasibility of diluting cell aliquots with buffer as a single step sample preparation technique for surface charge measurement was investigated by characterizing the effects of dilution ratio, cation type, and buffer conductivity on measuring surface charge of Escherichia coli DH5α (ATCC 53868) grown in LB Lennox medium. Results indicated that dilution ratio was critical to accurate surface charge measurement since poor signal-to-noise ratio in high or low cell concentration samples generated substantial error. Type of buffer cation was also important since putative binding of high affinity cations to the negatively-charged cell surface underestimated surface charge. Finally, high conductivity buffers enabled greater removal of adsorbed metabolites through increased charge screening; however, a broader statistical distribution of measured surface charge and less accurate data were also observed. At extreme conductivity values, measured surface charge exhibited multi-modal distribution; due probably to removal of both intrinsic cell surface ions and exogenous adsorbed metabolites, and called into question the accuracy of data. Altogether, one step dilution of cell aliquot with deionized water reliably reproduced E. coli surface charge values obtained using the gold standard approach. But, since the ensemble of secreted metabolites is bacteria and medium specific, distinct diluent and experimental parameters exist for each system. The described methodology may find use in preparing samples for cell surface characterization studies, where it would help reduce sample preparation time, and thus, improve temporal resolution at which scientific questions can be probed and answered.

scholarly journals Direct dilution of cell aliquot for high temporal resolution bacteria cell surface charge measurement

2016 ◽  
Author(s):  
Wenfa Ng ◽  
Yen-Peng Ting
Keyword(s):  
Cell Surface ◽  
Sample Preparation ◽  
Surface Charge ◽  
Temporal Resolution ◽  
Gold Standard ◽  
Preparation Technique ◽  
Dilution Ratio ◽  
Error Type ◽  
Gold Standard Method ◽  
Charge Measurement

Bacteria surface charge mediates important cell-environment and microbe-host interactions, and its accurate and precise measurement by microelectrophoresis requires removing metabolites adhered to the cell surface - where repeated centrifugation and washing by buffers is the gold standard method for sample preparation. Unfortunately, the need for time-consuming centrifugation limits the temporal resolution of sampling and profiling of experiment system dynamics; especially for samples requiring immediate treatment after sampling. Herein, the feasibility of diluting cell aliquots with buffer as a single step sample preparation technique for surface charge measurement was investigated by characterizing the effects of dilution ratio, cation type, and buffer conductivity on measuring surface charge of Escherichia coli DH5α (ATCC 53868) grown in LB Lennox medium. Results indicated that dilution ratio was critical to accurate surface charge measurement since low signal-to-noise ratio in high or low cell concentration samples generated substantial error. Type of buffer cation was also important since putative binding of high affinity cations to the negatively-charged cell surface underestimated surface charge. Finally, high conductivity buffers enabled greater removal of adsorbed metabolites through increased charge screening; however, a broader statistical distribution of measured surface charge and less accurate data were also observed. At extreme conductivity values, measured surface charge exhibited multi-modal distribution; due probably to removal of both intrinsic cell surface ions and exogenous adsorbed metabolites, and called into question the accuracy of data. Altogether, one step dilution of cell aliquot with deionized water reliably reproduced E. coli surface charge values obtained using the gold standard approach. But, since the ensemble of secreted metabolites is bacteria and medium specific, distinct diluent and experiment parameters exist for each system. The described methodology may find use in preparing samples for cell surface characterization studies, where it would help reduce sample preparation time – and thus, improve temporal resolution at which scientific questions can be probed and answered.

scholarly journals Direct dilution of cell aliquot for high temporal resolution bacterial surface charge measurement

2016 ◽  
Author(s):  
Wenfa Ng ◽  
Yen-Peng Ting
Keyword(s):  
Cell Surface ◽  
Sample Preparation ◽  
Surface Charge ◽  
Temporal Resolution ◽  
Gold Standard ◽  
Preparation Technique ◽  
Dilution Ratio ◽  
Bacterial Surface ◽  
Charge Measurement ◽  
One Step

Bacterial surface charge mediates important cell-environment and microbe-host interactions, and its accurate and precise measurement by microelectrophoresis requires removing metabolites adhered to the cell surface - where repeated centrifugation and washing by buffers is the gold standard sample preparation method. Unfortunately, the need for time-consuming centrifugation limits the temporal resolution of sampling and profiling of experimental dynamics; especially for samples requiring immediate treatment after sampling. Herein, the feasibility of diluting cell aliquots with buffer as a one step sample preparation technique for surface charge measurement was investigated by characterizing the effects of dilution ratio, cation type, and buffer conductivity on measuring surface charge of Escherichia coli DH5α (ATCC 53868) grown in LB Lennox medium. Results indicated that dilution ratio was critical to accurate surface charge measurement since low signal-to-noise ratio in high or low cell concentration samples generated substantial error. Type of buffer cation was also important since putative binding of high affinity cations to the cell surface underestimated surface charge of negatively charged bacteria. Finally, high conductivity buffers enabled greater removal of adsorbed metabolites through increased charge screening. However, a broader statistical distribution of measured surface charge was also observed – which, at extreme conductivity values, led to inaccurate data; probably due to removal of both intrinsic cell surface ions and exogenous adsorbed metabolites. Altogether, one step dilution of cell aliquot with deionized water reliably reproduced E. coli surface charge values obtained via the gold standard approach. But, since the ensemble of secreted metabolites is bacteria and/or medium specific, distinct diluent and experiment parameters exist for each system. The described methodology may find use in preparing samples for cell surface characterization studies, where it would help reduce sample preparation time – and thus, improve temporal resolution at which scientific questions can be probed and answered.

scholarly journals Direct dilution of cell aliquot for high temporal resolution bacterial surface charge measurement

2015 ◽  
Author(s):  
Wenfa Ng ◽  
Yen-Peng Ting
Keyword(s):  
Cell Surface ◽  
Sample Preparation ◽  
Surface Charge ◽  
Temporal Resolution ◽  
Gold Standard ◽  
Preparation Technique ◽  
Dilution Factor ◽  
Error Type ◽  
Bacterial Surface ◽  
One Step

Bacterial surface charge (SC) mediates important cell-environment and microbe-host interactions, and its accurate and precise measurement by microelectrophoresis requires removing metabolites adhered to the cell surface - where repeated centrifugation and washing by buffers is the gold standard method. Unfortunately, the need for time-consuming centrifugation limits the temporal resolution of sampling and interrogation of experimental dynamics; especially for samples requiring immediate treatment post sampling. Herein, the feasibility of diluting cell aliquots with buffer as a one-step sample preparation technique for SC measurement was investigated by characterising the effects of dilution factor, type of cation, and buffer conductivity on measuring SC of Escherichia coli DH5α grown in LB medium. Results indicated that dilution factor was critical to accurate SC measurement since low signal-to-noise ratios in high or low cell concentration samples generated substantial error. Type of buffer cation was also important since putative binding of high affinity cations to the cell surface underestimated SC of negatively-charged bacteria. Finally, although high conductivity buffers enabled greater removal of adsorbed metabolites through increased charge screening, a broader statistical distribution of measured SC was also observed – which, at extreme conductivity values, led to inaccurate data, probably due to removal of both intrinsic cell surface ions and exogenous adsorbed metabolites. Altogether, one-step dilution of cell aliquot with deionized water reliably reproduced E. coli SC values obtained via the gold standard approach; however, since the ensemble of secreted metabolites is bacteria/medium specific, distinct diluent and optimal parameters exist for each system. The described methodology may find use in preparing samples for cell surface characterisation studies, where it would help reduce sample preparation time – and thus, improve temporal resolution at which scientific questions can be probed and answered.

scholarly journals Direct dilution of cell aliquot for high temporal resolution bacterial surface charge measurement

2013 ◽  
Author(s):  
Wenfa Ng
Keyword(s):  
Cell Surface ◽  
Sample Preparation ◽  
Surface Charge ◽  
Temporal Resolution ◽  
Gold Standard ◽  
Standard Approach ◽  
Preparation Technique ◽  
Dilution Factor ◽  
Bacterial Surface ◽  
One Step

Bacterial surface charge (SC) mediates important cell-environment and microbe-host interactions, and its accurate and precise measurement by microelectrophoresis requires removing metabolites adhered to the cell surface - where repeated centrifugation and washing by buffers is the gold standard approach. Unfortunately, the need for time-consuming centrifugation limits the temporal resolution of sampling and interrogation of experimental dynamics; especially for samples requiring immediate treatment post sampling. Herein, the feasibility of diluting cell aliquots with buffer as a one-step sample preparation technique for SC measurement was investigated by characterising the effects of dilution factor, type of cation, and buffer conductivity on measuring SC of Escherichia coli DH5α grown in LB medium. Results indicated that dilution factor was critical to accurate SC measurement since low signal-to-noise ratios in high or low cell concentration samples generated substantial error. Type of buffer cation was also important since putative binding of high affinity cations to the cell surface underestimated SC of negatively-charged bacteria. Finally, although high conductivity buffers enabled greater removal of adsorbed metabolites through increased charge screening, a broader statistical distribution of measured SC was also observed – which, at extreme conductivity values, led to inaccurate data, probably due to removal of both intrinsic cell surface ions and exogenous adsorbed metabolites. Altogether, one-step dilution of cell aliquot with deionized water reliably reproduced E. coli SC values obtained via the gold standard approach; however, since the ensemble of secreted metabolites is bacteria/medium specific, distinct diluent and optimal parameters exist for each system. The described methodology may find use in preparing samples for cell surface characterisation studies, where it would help reduce sample preparation time – and thus, improve temporal resolution at which scientific questions can be probed and answered.

SEM evaluation of the TEM cold-stage double-film specimen

1984 ◽  
Vol 42 ◽  
pp. 272-273
Author(s):  
Jayesh Bellare
Keyword(s):  
Spatial Distribution ◽  
Sample Preparation ◽  
Sample Thickness ◽  
Specimen Preparation ◽  
Preparation Technique ◽  
Liquid Sample ◽  
Thin Specimen ◽  
Sample Preparation Technique ◽  
Cold Stage ◽  
Film Specimen

Seeing is believing, but only after the sample preparation technique has received a systematic study and a full record is made of the treatment the sample gets.For microstructured liquids and suspensions, fast-freeze thermal fixation and cold-stage microscopy is perhaps the least artifact-laden technique. In the double-film specimen preparation technique, a layer of liquid sample is trapped between 100- and 400-mesh polymer (polyimide, PI) coated grids. Blotting against filter paper drains excess liquid and provides a thin specimen, which is fast-frozen by plunging into liquid nitrogen. This frozen sandwich (Fig. 1) is mounted in a cooling holder and viewed in TEM.Though extremely promising for visualization of liquid microstructures, this double-film technique suffers from a) ireproducibility and nonuniformity of sample thickness, b) low yield of imageable grid squares and c) nonuniform spatial distribution of particulates, which results in fewer being imaged.

A technique for preparing semiconductor cross sections for both TEM and SEM analysis

1989 ◽  
Vol 47 ◽  
pp. 712-713
Author(s):  
Stanley J. Klepeis ◽  
J.P. Benedict ◽  
R.M Anderson
Keyword(s):  
Sample Preparation ◽  
Cross Section ◽  
Cross Sections ◽  
Sem Analysis ◽  
Preparation Technique ◽  
Ion Milling ◽  
Tem Analysis ◽  
Polished Cross Section ◽  
Area Of Interest ◽  
Polished Side

The ability to prepare a cross-section of a specific semiconductor structure for both SEM and TEM analysis is vital in characterizing the smaller, more complex devices that are now being designed and manufactured. In the past, a unique sample was prepared for either SEM or TEM analysis of a structure. In choosing to do SEM, valuable and unique information was lost to TEM analysis. An alternative, the SEM examination of thinned TEM samples, was frequently made difficult by topographical artifacts introduced by mechanical polishing and lengthy ion-milling. Thus, the need to produce a TEM sample from a unique,cross-sectioned SEM sample has produced this sample preparation technique.The technique is divided into an SEM and a TEM sample preparation phase. The first four steps in the SEM phase: bulk reduction, cleaning, gluing and trimming produces a reinforced sample with the area of interest in the center of the sample. This sample is then mounted on a special SEM stud. The stud is inserted into an L-shaped holder and this holder is attached to the Klepeis polisher (see figs. 1 and 2). An SEM cross-section of the sample is then prepared by mechanically polishing the sample to the area of interest using the Klepeis polisher. The polished cross-section is cleaned and the SEM stud with the attached sample, is removed from the L-shaped holder. The stud is then inserted into the ion-miller and the sample is briefly milled (less than 2 minutes) on the polished side. The sample on the stud may then be carbon coated and placed in the SEM for analysis.

TEM sample preparation of wear-tested room-temperature pulsed-laser-deposited thin films of MoS2 by ultramicrotomy

1993 ◽  
Vol 51 ◽  
pp. 1118-1119
Author(s):  
Pamela F. Lloyd ◽  
Scott D. Walck
Keyword(s):  
Thin Films ◽  
Sample Preparation ◽  
Room Temperature ◽  
High Vacuum ◽  
Pulsed Laser ◽  
Ultra High Vacuum ◽  
Wear Testing ◽  
Preparation Technique ◽  
Cross Sectional ◽  
Aerospace Applications

Pulsed laser deposition (PLD) is a novel technique for the deposition of tribological thin films. MoS2 is the archetypical solid lubricant material for aerospace applications. It provides a low coefficient of friction from cryogenic temperatures to about 350°C and can be used in ultra high vacuum environments. The TEM is ideally suited for studying the microstructural and tribo-chemical changes that occur during wear. The normal cross sectional TEM sample preparation method does not work well because the material’s lubricity causes the sandwich to separate. Walck et al. deposited MoS2 through a mesh mask which gave suitable results for as-deposited films, but the discontinuous nature of the film is unsuitable for wear-testing. To investigate wear-tested, room temperature (RT) PLD MoS2 films, the sample preparation technique of Heuer and Howitt was adapted.Two 300 run thick films were deposited on single crystal NaCl substrates. One was wear-tested on a ball-on-disk tribometer using a 30 gm load at 150 rpm for one minute, and subsequently coated with a heavy layer of evaporated gold.

Introduction of a Novel Sample Preparation Technique for the Failure Analysis of Silicon Integrated Photonics Modules

2019 ◽  
Author(s):  
Pradip Sairam Pichumani ◽  
Fauzia Khatkhatay
Keyword(s):  
Sample Preparation ◽  
Failure Analysis ◽  
Silicon Photonics ◽  
Cmos Technology ◽  
Single Step ◽  
Oxide Semiconductor ◽  
Disruptive Technology ◽  
Preparation Technique ◽  
Test Vehicle ◽  
Sample Preparation Technique

Abstract Silicon photonics is a disruptive technology that aims for monolithic integration of photonic devices onto the complementary metal-oxide-semiconductor (CMOS) technology platform to enable low-cost high-volume manufacturing. Since the technology is still in the research and development phase, failure analysis plays an important role in determining the root cause of failures seen in test vehicle silicon photonics modules. The fragile nature of the test vehicle modules warrants the development of new sample preparation methods to facilitate subsequent non-destructive and destructive analysis methods. This work provides an example of a single step sample preparation technique that will reduce the turnaround time while simultaneously increasing the scope of analysis techniques.

A Modified QuEChERS Extraction and LC-MS/MS Method for the Determination of Pesticide Residues in Curry Leaves (Murraya koenigii)

2019 ◽  
Vol 6 (1) ◽  
pp. 30-41
Author(s):  
Ranjith Arimboor ◽  
Karunkara Ramakrishna Menon ◽  
Natarajan Ramesh Babu ◽  
Haneesh Chandran
Keyword(s):  
Sample Preparation ◽  
Matrix Effect ◽  
Retention Time ◽  
Pesticide Residues ◽  
Mobile Phase ◽  
Preparation Technique ◽  
Modified Quechers ◽  
Curry Leaves ◽  
Ms Analysis ◽  
The Matrix

Background:Increased consumer demand for curry leaves free from pesticides demands fast and reliable analytical methods for the analysis of pesticide residues.Objective:The optimization of a QuEChERS based sample preparation technique with improved analytical accuracy by removing interfering matrix components for LC-MS/MS analysis of pesticide residues from curry leaves.Methods:A modified QuEChERS solid phase extraction method was developed and validated for the analysis of 26 pesticides in fresh and dried curry leaves. The effects of the sample preparation steps and column retention time on the matrix suppression of analyte ions were also evaluated.Results:Validation parameters were found within an acceptable range. The matrix effect evaluation studies showed that the QuEChERS sample preparation was able to minimize the ion suppression of analytes due to co-eluting matrix of components and that a d-SPE clean up step had major role in reducing matrix effect. The gradient mobile phase with longer retention time for analytes resulted in comparatively lesser matrix effects than the isocratic mobile phase of non-polar nature. Even after the clean up, a considerable number of compounds had more than 20% reduction in their MS response in the gradient mobile phase.Conclusion:This study emphasized the need of proper sample clean up before a LC-MS/MS analysis and the usage of matrix matched standards and mobile phase that ultimately results in an appropriate analyte separation in reasonable retention times.

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