Capture of latex beads, bacteria, endotoxin, and viruses by charge-modified filters

Abstract

This report demonstrates how electropositive filters can be used to enhance the removal of microorganisms and other negatively charged particles from water. It was shown that electropositive depth filters were capable of adsorbing viruses and endotoxins many times smaller than the average pore size of the filter. Electronegative filters of similar porosity or electropositive filters that had been treated to destroy the positive charge were almost ineffective under similar conditions for the removal of viruses and small latex spheres. The results of this study indicate that electropositive filters are highly effective in the removal of a wide range of contaminants over a wide range of pH values and ionic conditions.

Rapid Detection of Salmonella spp. by Using Felix-O1 Bacteriophage and High-Performance Liquid Chromatography

“…The use of electropositive largepore filters has been shown to be very effective in removing Salmonella spp. and other microorganisms from water and sewage (5,7,8,11). Subsequent elution of these bacteria into nutrient broth would allow for the detection of Salmonella spp.…”

State‐of‐the‐art in downstream processing of monoclonal antibodies: Process trends in design and validation

“…This is particularly relevant as the process impurities frequently encountered can be negatively charged at harvest pH and can form colloids during the cell culture and harvesting processes 40. For example, positively charged depth filters can be used to remove endotoxins,42, 43 viral particles,43 DNA,44, 45 and host cell protein (HCP) 40…”

“…The successful control of parameters and optimal conditions in previous upstream and downstream steps highly influence polishing design. The appropriate selection of the harvest depth filter chemistry, flux, and volumetric load helps to reduce the level of turbidity and HCP in the Protein A column eluate 43, 69…”

Chapter 9 The Detection of Waterborne Viruses

“…Positively charged filters adsorb virus from water and other materials without the need for prior conditioning of the sample. Initial work was done in the USA by Sobsey and Jones (1979) and by Hou et al (1980). They adsorb virus in the pH range 3-6; at pH values above 7 the adsorption falls off rapidly, so the pH still needs to be carefully controlled.…”