scholarly journals Quantifying Diffusion in a Biofilm ofStreptococcus mutans

2010 ◽  
Vol 55 (3) ◽  
pp. 1075-1081 ◽  
Author(s):  
Zeshi Zhang ◽  
Elena Nadezhina ◽  
Kevin J. Wilkinson
Keyword(s):  
Ionic Strength ◽  
Fluorescent Probes ◽  
Diffusion Coefficients ◽  
Correlation Spectroscopy ◽  
Fluorescence Correlation ◽  
Self Diffusion ◽  
Probe Size ◽  
Order Of Magnitude ◽  
Biofilm Heterogeneity ◽  
Insight Into

ABSTRACTIn biofilms, diffusion may limit the chemical activity of nutrients, toxic compounds, and medicines. This study provides direct, noninvasive insight into the factors that will most effectively limit the transport of antibiotics and biocides in biofilms. Self-diffusion coefficients have been determined for a number of fluorescent probes in biofilms ofStreptococcus mutansusing fluorescence correlation spectroscopy. The effects of probe size and charge and the roles of biofilm pH, ionic strength, and heterogeneity were studied systematically. The relative diffusion coefficients (Din the biofilm divided by that in water) decreased with increasing probe size (3,000-molecular-weight [3K], 10K, 40K, 70K, and 2,000K dextrans). Studies using variably charged substrates (tetramethylrhodamine, Oregon Green, rhodamine B, and rhodamine 6G) showed that the self-diffusion coefficients decreased with an increasing negative charge of the fluorescent probes. No significant effect was observed for changes to the ionic strength (10−4to 10−1M) or pH (4 to 9) of the biofilm. Biofilm heterogeneity was responsible for variations of ca. one order of magnitude in the diffusion coefficients.

Self-diffusion of a highly concentrated monoclonal antibody by fluorescence correlation spectroscopy: insight into protein–protein interactions and self-association

Soft Matter ◽  
2019 ◽  
Vol 15 (33) ◽  
pp. 6660-6676 ◽  
Author(s):  
Jessica J. Hung ◽  
Wade F. Zeno ◽  
Amjad A. Chowdhury ◽  
Barton J. Dear ◽  
Kishan Ramachandran ◽  
...  
Keyword(s):  
Monoclonal Antibody ◽  
Protein Interactions ◽  
Fluorescence Correlation Spectroscopy ◽  
Correlation Spectroscopy ◽  
Protein Protein Interactions ◽  
Fluorescence Correlation ◽  
Self Diffusion ◽  
Self Association ◽  
Insight Into

Measurement and interpretation of self-diffusion of a highly concentrated mAb with different formulations in context of viscosity and protein self-interactions.

The role of charge on the diffusion of solutes and nanoparticles (silicon nanocrystals, nTiO2, nAu) in a biofilm

2013 ◽  
Vol 10 (1) ◽  
pp. 34 ◽  
Author(s):  
Mahmood Golmohamadi ◽  
Rhett J. Clark ◽  
Jonathan G. C. Veinot ◽  
Kevin J. Wilkinson
Keyword(s):  
Carboxylic Acid ◽  
Diffusion Coefficients ◽  
Electrostatic Interactions ◽  
Emerging Contaminants ◽  
Correlation Spectroscopy ◽  
Fluorescence Correlation ◽  
Self Diffusion ◽  
Wide Range ◽  
Tetramethylrhodamine Methyl Ester

Environmental context The mobility and bioavailability of both contaminants and nutrients in the environment depends, to a large extent, on their diffusion. Because the majority of microorganisms in the environment are embedded in biofilms, it is essential to quantify diffusion in biofilms in order to evaluate the risk of emerging contaminants, including nanomaterials and charged solutes. This study quantifies diffusion, in a model environmental biofilm, for a number of model contaminants of variable size and charge. Abstract The effect of solute and biofilm charge on self-diffusion (Brownian motion) in biofilms is examined. Diffusion coefficients (D) of several model (fluorescent) solutes (rhodamine B; tetramethylrhodamine, methyl ester; Oregon Green 488 carboxylic acid, succinimidyl ester and Oregon Green 488 carboxylic acid) and nanoparticles (functionalised silicon, gold and titanium) were determined using fluorescence correlation spectroscopy (FCS). Somewhat surprisingly, little effect due to charge was observed on the diffusion measurements in the biofilms. Furthermore, the ratio of the diffusion coefficient in the biofilm with respect to that in water (Db/Dw) remained virtually constant across a wide range of ionic strengths (0.1–100mM) for both negatively and positively charged probes. In contrast, the self-diffusion coefficients of nanoparticles with sizes >10nm greatly decreased in the biofilms with respect to those in water. Furthermore, much larger nanoparticles (>66nm) appeared to be completely excluded from the biofilms. The results indicated that for many oligotrophic biofilms in the environment, the diffusion of solutes and nanoparticles will be primarily controlled by obstruction rather than electrostatic interactions. The results also imply that most nanomaterials will become significantly less mobile and less bioavailable (to non-planktonic organisms) as they increase in size beyond ~10nm.

Monte Carlo simulation of fluorescence correlation spectroscopy data

2011 ◽  
Vol 76 (3) ◽  
pp. 207-222 ◽  
Author(s):  
Peter Košovan ◽  
Filip Uhlík ◽  
Jitka Kuldová ◽  
Miroslav Štěpánek ◽  
Zuzana Limpouchová ◽  
...  
Keyword(s):  
Monte Carlo Simulation ◽  
Monte Carlo ◽  
Diffusion Coefficients ◽  
Fluorescence Correlation Spectroscopy ◽  
Rotational Diffusion ◽  
Correlation Spectroscopy ◽  
Analytical Models ◽  
Spherical Particles ◽  
Fluorescence Signal ◽  
Fluorescence Correlation

We employed the Monte Carlo simulation methodology to emulate the diffusion of fluorescently labeled particles and understand the source of differences between values of diffusion coefficients (and consequently hydrodynamic radii) of fluorescently labeled nanoparticles measured by fluorescence correlation spectroscopy (FCS) and dynamic light scattering (DLS). We used the simulation program developed in our laboratory and studied the diffusion of spherical particles of different sizes, which are labeled on their surface. In this study, we focused on two complicating effects: (i) multiple labeling and (ii) rotational diffusion which affect the fluorescence signal from large particles and hinder the analysis of autocorrelation functions according to simple analytical models. We have shown that the fluorescence fluctuations can be well fitted using the analytical model for small point-like particles, but the obtained parameters deviate in some cases significantly from the real ones. It means that the current data treatment yields apparent values of diffusion coefficients and other parameters only and the interpretation of experimental results for systems of particles with sizes comparable to the size of the active illuminated volume requires great care and precaution.

Accurate Diffusion Coefficients of Organosoluble Reference Dyes in Organic Media Measured by Dual-Focus Fluorescence Correlation Spectroscopy

ACS Nano ◽  
2015 ◽  
Vol 9 (7) ◽  
pp. 7360-7373 ◽  
Author(s):  
Karel Goossens ◽  
Mira Prior ◽  
Victor Pacheco ◽  
Dieter Willbold ◽  
Klaus Müllen ◽  
...  
Keyword(s):  
Diffusion Coefficients ◽  
Fluorescence Correlation Spectroscopy ◽  
Correlation Spectroscopy ◽  
Organic Media ◽  
Fluorescence Correlation

Solution and Diffusion in Silicone Rubber. I. A Comparison with Natural Rubber

1963 ◽  
Vol 36 (3) ◽  
pp. 642-650 ◽  
Author(s):  
R. M. Barrer ◽  
J. A. Barrie ◽  
N. K. Raman
Keyword(s):  
Statistical Theory ◽  
Natural Rubber ◽  
Silicone Rubber ◽  
Diffusion Coefficients ◽  
Molecular Size ◽  
Low Energy ◽  
Kcal Mole ◽  
Self Diffusion ◽  
Order Of Magnitude ◽  
And Diffusion

Abstract The diffusion and solubility of n- and isobutane and of n- and neopentane has been studied in the range 30° to 70° C, in polydimethylsiloxane rubbers. The solubilities are very similar to those in natural rubbers and show comparable agreement with the statistical theory of polymer penetrant mixtures. Diffusion coefficients are at least an order of magnitude greater in silicone than in natural rubbers. The very low energy of activation, ED, of about 4 kcal/mole is almost invariant among the hydrocarbons studied and is the same as for self-diffusion and viscous flow in this rubber. The low value of ED means that permeabilities of the hydrocarbons increase as the temperature falls. Because diffusion in silicones is less dependent upon molecular size and shape of penetrant than in natural rubber, the silicones are less selective though much more permeable separation barriers.

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