Virus removal membrane
A virus removal membrane is formed from a hydrophilized synthetic polymer, in which, when a solution containing gold colloids having a diameter of 20 nm is applied through a primary surface to the virus removal membrane to allow the virus removal membrane to capture the gold colloids for measurement of brightness in a cross section of the virus removal membrane, a value obtained by dividing a standard deviation of a value of an area of a spectrum of variation in the brightness by an average of the value of the area is 0.01 or more and 1.5 or less; and a thickness of a portion, where gold colloids having a diameter of 20 nm or more and 30 nm or less are captured, in the cross section of the virus removal membrane in a wet state is 10 μm or more and 30 μm or less.
1. A virus removal membrane for removing viruses from a protein-containing solution,
the virus removal membrane comprising:
a primary surface configured to have the protein-containing solution applied thereto, and
a secondary surface configured to allow a liquid that permeates through a thickness of the virus removal membrane to flow therefrom, wherein,
a body of the virus removal membrane is configured such that,
i) a value obtained by dividing a standard deviation of a value of an area of a spectrum of variation in brightness by an average of the value of the area of the spectrum of variation in the brightness is 0.01 or more and 1.50 or less, wherein the brightness is measured for a cross section of the virus removal membrane after 40 mL of a solution containing gold colloids having a diameter of 20 nm is applied to a filtration area of 0.001 m 2 of the primary surface, filtered under a pressure of 196 kPa, and penetrates into the body of the virus removal membrane to allow the virus removal membrane to capture the gold colloids for measurement of brightness; and
ii) a thickness of a portion where gold colloids having a diameter of 20 nm or more and 30 nm or less are captured in the cross section of the virus removal membrane in a wet state is 10 μm or more and 28.0 μm or less, wherein the thickness is measured after 40 mL of a solution containing gold colloids having a diameter of 20 nm or more and 30 nm or less is applied to the filtration area of 0.001 m 2 of the primary surface, filtered under a pressure of 196 kPa, and penetrates into the body of the virus removal membrane,
wherein
the body of the virus removal membrane is configured such that
a portion where gold colloids having a diameter of 30 nm are captured is located at a place corresponding to 15% or more and 60% or less of a thickness of the virus removal membrane from the primary surface in the cross section of the virus removal membrane in a wet state after 40 mL of a solution containing the gold colloids having a diameter of 30 nm is applied to the filtration area of 0.001 m 2 of the primary surface, filtered under a pressure of 196 kPa, and penetrates into the body of the virus removal membrane,
a portion where gold colloids having a diameter of 20 nm are captured is located at a place corresponding to 25% or more and 85% or less of the membrane thickness from the primary surface in the cross section of the virus removal membrane in a wet state after 40 mL of a solution containing the gold colloids having a diameter of 20 nm is applied to the filtration area of 0.001 m 2 of the primary surface, filtered under a pressure of 196 kPa, and penetrates into the body of the virus removal membrane, and
a portion where gold colloids having a diameter of 15 nm are captured is located at a place corresponding to 60% or more and 100% or less of the membrane thickness from the primary surface in the cross section of the virus removal membrane in a wet state after 40 mL of a solution containing the gold colloids having a diameter of 15 nm is applied to the filtration area of 0.001 m 2 of the primary surface, filtered under a pressure of 196 kPa, and penetrates into the body of the virus removal membrane,
wherein each of the solutions containing gold colloids are diluted with distilled water for injection, 1.59% by volume of polyoxyethylene-naphthyl ether, and 0.20% by volume of poly(sodium 4-styrenesulfonate) so that the absorbance at the maximum absorption wavelength of the gold colloids of the solution is 0.25 measured by an ultraviolet-visible spectrophotometer,
and
the virus removal membrane is formed of a hydrophilized synthetic polymer.
2. The virus removal membrane according to claim 1 , wherein the body of the virus removal membrane is configured such that, when 40 mL of a solution containing gold colloids having a diameter of 10 nm is applied to the filtration area of 0.001 m 2 of the primary surface, filtered under a pressure of 196 kPa, and penetrates into the body of the virus removal membrane, gold colloids having a diameter of 10 nm are not captured,
wherein the solution containing gold colloids having a diameter of 10 nm is diluted with distilled water for injection, 1.59% by volume of polyoxyethylene-naphthyl ether, and 0.20% by volume of poly(sodium 4-styrenesulfonate) so that the absorbance at the maximum absorption wavelength of the gold colloids of the solution is 0.25 measured by an ultraviolet-visible spectrophotometer.
3. The virus removal membrane according to claim 1 , wherein a logarithmic removal rate of gold colloid having a diameter of 30 nm is 1.00 or more,
a logarithmic removal rate of gold colloid having a diameter of 20 nm is 1.00 or more,
a logarithmic removal rate of gold colloid having a diameter of 15 nm is 0.10 or more, and
a logarithmic removal rate of gold colloid having a diameter of 10 nm is less than 0.10.
4. The virus removal membrane according to claim 1 , wherein a pore size of a pore is decreased and is then constant, from the primary surface towards the secondary surface in the cross section of the virus removal membrane, and the virus removal membrane has a densest layer in the vicinity of the secondary surface.
5. The virus removal membrane according to claim 1 , wherein a thickness of the membrane is 40.0 μm or more and 60.0 μm or less in a dry state.
6. The virus removal membrane according to claim 1 , wherein a bubble point is 1.30 MPa or more and 1.80 MPa or less.
7. The virus removal membrane according to claim 1 , wherein a ratio of a bubble point (MPa) to a surface tension (N/m) is 96 or more and 133 or less.
8. The virus removal membrane according to claim 1 , wherein a pure water permeation rate is 30 L/m 2 /hrs/0.1 MPa, or more and 80 L/m 2 /hrs/0.1 MPa, or less.
9. The virus removal membrane according to claim 1 , which is a hollow fiber membrane.
10. The virus removal membrane according to claim 1 , which is a flat membrane.
11. The virus removal membrane according to claim 1 , comprising a thermoplastic crystalline polymer.
12. The virus removal membrane according to claim 1 , comprising a hydrophilic graft chain.
13. The virus removal membrane according to claim 1 , wherein the body of the virus removal membrane is configured such that, when the solution containing gold colloids having the diameter of 15 nm is applied to the primary surface and penetrates into the body of the virus removal membrane, a thickness of a portion where gold colloids having a diameter of 15 nm are captured in a cross section of the virus removal membrane in a wet state is 2 μm or more and 10 μm or less.
14. The virus removal membrane according to claim 1 , further comprising: the body of the virus removal membrane being cooled and solidified by bringing the virus removal membrane into contact with water having a temperature of 30.0° or less.
15. The virus removal membrane according to claim 1 , wherein the body of the virus removal membrane is a hollow fiber membrane having a uniform structure in the circumferential direction.
16. The virus removal membrane according to claim 1 , wherein the thickness of the portion where the gold colloids having the diameter of 20 nm or more and 30 nm or less are captured in the cross section of the virus removal membrane in the wet state is 26.4 μm or less.