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
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
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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?
Wet a single membrane filter (either GSWP 013 00 or HAWP 013 00) with Milli-Q water and blot it to absorbent paper to remove excess water.
Glue the filter to one side of a diffusion chamber ring without hole (catalog number PR00 014 00), using MF cement (catalog number XX70 000 00), and let dry.
Sterilize this assembly, along with another membrane filter of the same type, by exposure to ethylene oxide gas or ultraviolet light.
Moisten the half-completed chamber and the separate sterile filter with a sterile physiological solution, and aseptically place the tissue to be studied in the half-completed chamber assembly.
Glue the cover filter in place using sterile technique.
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).
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.
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.
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.
C7631Durapore® membranes made with Polyvinylidene fluoride (PVDF) provide high flow rates and throughput, low extractables and broad chemical compatibility.
Durapore® membranes provide high flow rates and throughput, low extractables and broad chemical compatibility. Hydrophlic Durapore® membrane binds far less protein than nylon, nitrocellulose, or PTFE membranes.
Features & Benefits
Available in several pore sizes (both hydrophilic and hydrophobic varieties) to suit your application needs
Durapore® membrane filters have very low protein binding to minimize interaction with your sample and maximize recovery
Color: white Surface: plain Thickness: 125 µm Sterilization: by autoclave (121 °C at 1 bar), EO or gamma Operating temperature: 85 °C max. Bacterial endotoxins: 0.5 EU/mL Gravimetric extractables: < 0.5%
Bubble Point (psi)
Water Flow Rate2 (mL/min/cm²)
Typical Air Flow3 (L/min/cm²)
Protein Binding (µg/cm2)
0.1 µm pore size, hydrophilic PVDF, 13 mm membrane
≥75 psi, air with water
0.22 µm pore size, hydrophilic PVDF, 13 mm membrane
≥50 psi, air with water
0.45 µm pore size, hydrophilic PVDF, 13 mm membrane
≥22 psi, air with water
0.65 µm pore size, hydrophilic PVDF, 13 mm membrane
≥15 psi, air with water
Clarifying filtration of biological solutions, particle monitoring
≥3 psi, air with water
0.1 µm pore size, hydrophobic PVDF, 47 mm membrane
≥26 psi, air with methanol
0.22 µm pore size, hydrophobic PVDF, 47 mm membrane
≥18 psi, air with methanol
0.45 µm pore size, hydrophobic PVDF, 47 mm membrane
≥9 psi, air with methanol
1Corresponds to first 4 digits of catalogue number. 2Water Flow Rate measured with 500 mL of water at 25 oC and 27.5 inHg vacuum through 47 mm disc. 3Air flow rate measured at 10 psi. Values represent typical performance and are not established specifications.