Capillary Electrophoresis Measurements of Electrophoretic Mobility for Colloidal Particles of Biological Interest

Abstract

The electrophoretic mobilities of three bacterial strains were investigated by capillary electrophoresis (CE) and were compared with results obtained by microelectrophoresis (ME). The CE measurements yielded bimodal electropherograms for two of the strains, thus illustrating for the first time that surface charge variations within a monoclonal population can be probed by CE. Intrapopulation variations were not detected by ME. The mobilities of three chemically distinct types of latex microspheres were also measured. Differences between the mean mobilities obtained by CE and ME were not statistically significant (P ≤ 0.50); the standard deviations of the CE measurements were typically 2 to 10 times smaller than those obtained by comparable ME measurements. The reproducibility of CE permitted batch-to-batch mobility variations to be probed for the bacteria (one of the strains exhibited such variations), and aggregation was evident in one of the latex suspensions. These effects were not measurable with ME.

Influence of Surface Characteristics on the Stability of Cryptosporidium parvum Oocysts

“…1a shows that there was a distribution of CML microspheres with various surface charges. Similar findings have been reported for latex spheres (13) and single-strain microbial populations (38). Figure 1a shows that the electrophoretic mobility of the CML microspheres was ca.…”

Influence of Surface Characteristics on the Stability of Cryptosporidium parvum Oocysts

“…1a shows that there was a distribution of CML microspheres with various surface charges. Similar findings have been reported for latex spheres (13) and single-strain microbial populations (38). Figure 1a shows that the electrophoretic mobility of the CML microspheres was ca.…”

Change of Collision Efficiency with Distance in Bacterial Transport Experiments

“…Because bacteria transported long distances are preferentially transported through coarse‐grained media, which tend to be low in grain coatings and quartz dominated, it is expected that transport of more negatively charged cells will be favored (because quartz surfaces tend to be negatively charged under typical ground water conditions and will therefore repel negatively charged cells). This would explain our observation that the average cell surface charge (as measured by ζ potential) decreased with greater transport distances and indicates that intra population variability in cell surface properties does play a role in the observed behavior, as previously observed in multiple studies (Albinger et al 1994; Baygents et al 1998; Glynn et al 1998; Simoni et al 1998; Bolster et al 1999, 2000). It would also potentially explain the apparent increased adhesiveness of cells collected at greater transport distances when injected into columns.…”

Dielectrophoretic Concentration and Separation of Live and Dead Bacteria in an Array of Insulators

“…The determination of the electrophoretic mobility of bacterial cells has been the focus of several studies. It has been found that the μ EP of bacteria depends on surface softness, structure and charge, and cell age, as well as ionic concentration and pH of the running buffer. ,, Armstrong et al − , have analyzed microorganisms using electrokinetic techniques. In the CE method for the determination of cell viability for B. infantis , L. acidophilus , and S. cerevisiae , peaks of live and dead cells had essentially the same migration times, indicating the same electrophoretic mobility .…”

“…Several studies found that the electrokinetic mobility of bacteria is mainly controlled by the EOF. This means that the μ EP is minimal when compared with the EOF. ,,, Li and Harrison 18 stated that in uncoated glass chips, the solvent mobility due to EOF is greater than the electrophoretic mobility of bacteria. The work cited above is consistent with the direct observation of the cell velocities in our laboratory.…”

Influence of Surface Characteristics on the Stability of Cryptosporidium parvum Oocysts

“…1a shows that there was a distribution of CML microspheres with various surface charges. Similar findings have been reported for latex spheres (13) and single-strain microbial populations (38). Figure 1a shows that the electrophoretic mobility of the CML microspheres was ca.…”

Change of Collision Efficiency with Distance in Bacterial Transport Experiments

“…Because bacteria transported long distances are preferentially transported through coarse‐grained media, which tend to be low in grain coatings and quartz dominated, it is expected that transport of more negatively charged cells will be favored (because quartz surfaces tend to be negatively charged under typical ground water conditions and will therefore repel negatively charged cells). This would explain our observation that the average cell surface charge (as measured by ζ potential) decreased with greater transport distances and indicates that intra population variability in cell surface properties does play a role in the observed behavior, as previously observed in multiple studies (Albinger et al 1994; Baygents et al 1998; Glynn et al 1998; Simoni et al 1998; Bolster et al 1999, 2000). It would also potentially explain the apparent increased adhesiveness of cells collected at greater transport distances when injected into columns.…”

Dielectrophoretic Concentration and Separation of Live and Dead Bacteria in an Array of Insulators

“…The determination of the electrophoretic mobility of bacterial cells has been the focus of several studies. It has been found that the μ EP of bacteria depends on surface softness, structure and charge, and cell age, as well as ionic concentration and pH of the running buffer. ,, Armstrong et al − , have analyzed microorganisms using electrokinetic techniques. In the CE method for the determination of cell viability for B. infantis , L. acidophilus , and S. cerevisiae , peaks of live and dead cells had essentially the same migration times, indicating the same electrophoretic mobility .…”

“…Several studies found that the electrokinetic mobility of bacteria is mainly controlled by the EOF. This means that the μ EP is minimal when compared with the EOF. ,,, Li and Harrison 18 stated that in uncoated glass chips, the solvent mobility due to EOF is greater than the electrophoretic mobility of bacteria. The work cited above is consistent with the direct observation of the cell velocities in our laboratory.…”

Influence of Surface Characteristics on the Stability of Cryptosporidium parvum Oocysts

“…1a shows that there was a distribution of CML microspheres with various surface charges. Similar findings have been reported for latex spheres (13) and single-strain microbial populations (38). Figure 1a shows that the electrophoretic mobility of the CML microspheres was ca.…”

Change of Collision Efficiency with Distance in Bacterial Transport Experiments

“…Because bacteria transported long distances are preferentially transported through coarse‐grained media, which tend to be low in grain coatings and quartz dominated, it is expected that transport of more negatively charged cells will be favored (because quartz surfaces tend to be negatively charged under typical ground water conditions and will therefore repel negatively charged cells). This would explain our observation that the average cell surface charge (as measured by ζ potential) decreased with greater transport distances and indicates that intra population variability in cell surface properties does play a role in the observed behavior, as previously observed in multiple studies (Albinger et al 1994; Baygents et al 1998; Glynn et al 1998; Simoni et al 1998; Bolster et al 1999, 2000). It would also potentially explain the apparent increased adhesiveness of cells collected at greater transport distances when injected into columns.…”

Dielectrophoretic Concentration and Separation of Live and Dead Bacteria in an Array of Insulators

“…The determination of the electrophoretic mobility of bacterial cells has been the focus of several studies. It has been found that the μ EP of bacteria depends on surface softness, structure and charge, and cell age, as well as ionic concentration and pH of the running buffer. ,, Armstrong et al − , have analyzed microorganisms using electrokinetic techniques. In the CE method for the determination of cell viability for B. infantis , L. acidophilus , and S. cerevisiae , peaks of live and dead cells had essentially the same migration times, indicating the same electrophoretic mobility .…”

“…Several studies found that the electrokinetic mobility of bacteria is mainly controlled by the EOF. This means that the μ EP is minimal when compared with the EOF. ,,, Li and Harrison 18 stated that in uncoated glass chips, the solvent mobility due to EOF is greater than the electrophoretic mobility of bacteria. The work cited above is consistent with the direct observation of the cell velocities in our laboratory.…”