US 12,260,976 B2
Magnetic bead and magnetic bead dispersion
Yasunari Ikeda, Shiojiri (JP); Michio Nakamori, Matsumoto (JP); and Hirofumi Hokari, Chino (JP)
Assigned to SEIKO EPSON CORPORATION, (JP)
Filed by SEIKO EPSON CORPORATION, Tokyo (JP)
Filed on Mar. 28, 2023, as Appl. No. 18/191,096.
Claims priority of application No. 2022-053050 (JP), filed on Mar. 29, 2022.
Prior Publication US 2023/0317332 A1, Oct. 5, 2023
Int. Cl. H01F 1/153 (2006.01); B22F 1/052 (2022.01); B22F 1/07 (2022.01); B22F 1/08 (2022.01); B22F 1/145 (2022.01); B22F 9/08 (2006.01)
CPC H01F 1/15383 (2013.01) [B22F 1/052 (2022.01); B22F 1/07 (2022.01); B22F 1/08 (2022.01); B22F 1/147 (2022.01); B22F 2009/0804 (2013.01); B22F 2301/35 (2013.01)] 6 Claims
OG exemplary drawing
 
1. A magnetic bead comprising:
a magnetic metal powder; and
a coating layer with which a particle surface of the magnetic metal powder is coated, the coating layer being a composite containing silicon and one or more selected from the group consisting of Al, Ti, V, Nb, Cr, Sn, and Zr,
wherein the coating layer includes a functional group configured to enhance binding of a biological substance to the magnetic bead, the functional group being selected from the group consisting of an OH group, an epoxy group, a trimethylsilyl group, and a NHS group,
an average particle size D50 of the magnetic bead is 0.5 μm or more and 50 μm or less,
a ratio D90/D50 of a 90% particle size D90 in a particle size distribution of the magnetic bead to the average particle size D50 is 2.00 or less, and
when the magnetic bead is left to stand in a state of a dispersion obtained by dispersing the magnetic bead in water, a time until an initial absorbance of the dispersion attenuates to 80% of an absorbance when the standing is started is 90 seconds or longer.