Embodiments of the present invention provide various multipolymers and permselective membranes for use with biosensors and other implantable medical devices and prostheses. Embodiments of the present invention may provide structural strength and integrity, and further may control the influx of glucose, oxygen and/or water. Embodiments of the present invention may, for example, minimize or reduce the influx of glucose by minimizing the percentage of hydrophilic segments, which in turn minimizes the percentage of water uptake and the degree of glucose transport.