Abstract: A membrane includes a plurality of nanopores, each nanopore including a first opening on a first side of the membrane, a second opening on a second side of the membrane, and an inner surface that extends between the first and second openings, wherein at least one nanopore comprises a positive surface charge zone extending along a portion of a length of the nanopore and a negative surface charge zone extending along a different portion of the length of the nanopore, wherein the inner surface of the nanopore has high-density positive surface charges within the positive surface charge zone and high-density negative surface charges within the negative surface charge zone.