The present invention generally relates to systems and methods for targeted removal of a substance or biomolecule such as a protein from a biological fluid, such as blood. In some cases, the blood may be withdrawn from a subject, treated, and returned to the subject. Previous techniques for removal of biological materials from blood, such as hemodialysis and plasmapheresis, were generally non-specific (i.e., they removed a multitude of proteins/toxins from the blood). By contrast, novel methods and devices described herein are capable of removing specific or single substances such as proteins from biological fluids such as blood in a specific manner. Such highly specific protein removal has a broad array of clinical applications, including treatment of inflammatory conditions and autoimmune diseases.