|OptiScale: a small scale screening tool for every application|
|Establishing Product Specific Bubble Point Specifications For Sterilizing-Grade (0.22 µm) Durapore® Filters|
|Sterile Filtration of Serum-free Mammalian Cell Culture Media|
|Colony filtration blot: a new screening method for soluble protein expression in Escherichia coli
Tobias Cornvik, Sue-Li Dahlroth, Audur Magnusdottir, Maria Dolores Herman, Rosemarie Knaust, Monica Ekberg & Pär Nordlund
Nature Methods, 2005 Jul:2(7):507-509 2005
|A functional study on polymorphism of the ATP-binding Cassette transpoter ABCG2:
Toshihisa Ishikawa,Biochem.J, 373, 767-774, 2003, internal ref ABC-02
Biochem.J, 373, 767-774, 2003, internal ref ABC-02 2003
|Comparison of microporous membrane morphologies using confocal scanning laser microscopy
Charcosset C (reprint), et al.
Journal of membrane science. 2000. v168, n2, p53-62 2000
|ATP/Mg2+-dependent Cardiac Transport system for Flutathione S-Conjugates
Toshihisa Ishikawa,J.Biological Chemistry, 264:29, 17343-17348, 1989, internal ref ABC-01
J.Biological Chemistry, 264:29, 17343-17348, 1989, internal ref ABC-01 1989
|How do I clear my Millipore filters?||It is possible to clear Millipore filters by choosing a clearing agent with the same refractive index as the membrane. This is called the PORE FILLING TECHNIQUE. Filters appear opaque because of the diffraction of light through the tortuous pores. Filling the pores with a liquid that has the same refractive index as the membrane (ex. xylene for MF filters) allows light to pass through the filter at a uniform speed thus rendering the filter transparent. This technique can be used for most membrane filters with a single refractive index. The refractive index for Durapore membrane is 1.42 and for MF membrane its 1.50.
Please note that this does not work for polycarbonate membranes because these membranes have more than one refractive index (1.62 and 1.58). If desired, the porous structure can be dissolved from Isopore polycarbonates by dissolving the filter in chloroform, methylene chloride or 1-methyl-2 pyrrolidone.
|What is the blue separation paper between my filters?||It is a parchmentalized paper specially formulated for Millipore Corporation.|
|How do I tell the membrane from the separator?||The blue paper is the separator.|
|How do I assemble a diffusion chamber containing tissue for implantation?||
|What are the dimensions and width of the grids on the Millipore 47mm gridded membranes?||The grids are 3.08mm x 3.08mm square. A grid line is 44um in width and there is are average of 169 gridded squares per filter. Please note however that the actual filtration area and therefore the total number of squares in that area is dependent on the filter holder. For filter holders with 9.6sq.cm of filtration area there are 100 squares available. For filter holders with 13.8 sq.cm of filtration area the number of available grids are approximately 140.|
|How do I assemble a diffusion chamber containing suspension cells for implantation?||Wet two membrane filters (either GSWP 013 00 or HAWP 013 00) with Milli-Q water and blot them to absorbent paper to remove excess water. Glue a moist filter to each side of the diffusion chamber ring with hole (catalog number PR00 014 01) using MF cement (catalog number XX70 000 00). Sterilize the dried diffusion chamber with ethylene oxide gas or ultraviolet light. After sterilization, inject the cells through the hole in the plastic ring, and plug the hole with the nylon thread which comes with the rings (catalog number PR00 000 00 if ordered separately).|
|Are the pore sizes of your Durapore membranes uniform or asymmetric?||The surfaces of the Durapore membrane are symmetric, however, the actual pores are not straight-through holes but rather follow a torturous path.|
|Which membrane should I use to filter my solution?||For general filtration use MCE. When you are looking for the lowest protein binding membrane use Durapore. For speed, and when filtering serum solutions use Millipore Express.|
|Which side of the membrane should I use, the shiny or dull side?||Most researchers may not even notice that there is a "sidedness" to filters, and, for most applications, orientation will not affect filter performance. However, membranes do have a slightly asymmetric pore structure: the shiny side of the membrane is the "tighter" side. In some applications, you can take advantage of this difference by selecting a specific filter orientation. ultrafiltration membranes should always be used shiny side up, regardless of application for drop dialysis ( a buffer exchange technique in which a few drops of DNA or protein are placed in a 0.05 or 0.025 um filter and floated on a buffer solution), apply the sample to the shiny side of the filter and float the filter dull side to the buffer. This measure will enhance buffer exchange and discourage sample loss. The Millipore Express and Express Plus membranees are also sided - these membranes should be used shiny side facing down.|
|Can I autoclave my filters?||Millipore's MF, Durapore, Fluoropore and Mitex filters are all autoclavable. Standard conditions of 121-126C for 20-30 min generally work quite well. However, the filters should be autoclaved on a "slow exhaust (liquid) cycle. Because Fluoropore membranes have a polyethylene backing they will be slightly wrinkled after autoclaving.|
|What is the difference between pore size and pore size distribution?||Whereas pore size is a measure of the diameter of the largest pore, pore size distribution is a measure of the range of pore sizes. The range of pore sizes can be normally distributed, and the spread can be quite narrow (e.g. the ratio of largest to smallest may be less than 2). On the other hand, pore size distribution can be very heterogeneous. In the case of large spreads and heterogeneity, the pore size will be far less predictive of flow rate (either filtration or capillary) than it will be for a membrane with a narrow pore size distribution. It is important to note that the pore size corresponding to the bubble point is not at the middle of the distribution, but is the largest pore.|
|Can Millipore filters remove mycoplasma from my solution?||Mycoplasma can be removed from solutions by using a 0.1 um pore size filter. For mycoplasma reduction the 0.1 um Durapore filter can be used. Its Millipore code is VV. A 0.1 um Express membrane can also be used for removal of mycoplasma. Its membrane code is VP. These membranes are available in a number of fabricated fiter devices. For help determining which device would be best for your solution, call Millipore Technical Services.|
|I would like to use the Durapore membrane discs and am interested in knowing what is meant by average pore size?||Since the size and uniformity of the Durapore membrane is accurately controlled during manufacturing, it is possible to rate membranes as absolute filters based on the largest particle that can pass through the membrane. It is then possible to confirm the pore size rating of the membrane filter using a non-destructive integrity test referred to as the bubble point test. This test is based on the fact that liquid is held in the membrane pores by surface tension and that the minimum pressure required to force liquid from the capillary structure is directly related to the capillary diameter.|
|I have a dilute protein solution. I want to make sure I do not lose any of my protein. Which filter should I use?||You should use any device that contains a Durapore filter. Durapore is the lowest protein-binding filter available. This filter will give the best yield when filtering a dilute protein solution.|
|How do I dissolve my Durapore membrane?||Hot DMF, DMSO, NMP will mostly dissolve hydrophobic GV & VV, but there still is an "insoluble" portion if you try to filter it. Phobic HV truely dissolves.
The hydrophilic versions can not be fully dissolved in part to the hydrophilic surface modification which is insoluble in all solvents.
We don't recommend Durapore for applications where the membrane needs to be dissolved. MCE is a great choice.
|Hydrophilic Durapore® Cartridges and Capsules User Guide|