Disclosed is a marking composition comprising a marker and a hydrogel. Disclosed is a process of forming a marking composition comprising mixing a marker and a hydrogel. Disclosed is an article comprising a marker, a hydrogel, and an implement. Disclosed is a kit comprising a marker, a hydrogel, and an implement, wherein the marker and hydrogel are combined. Disclosed is a method for marking a portion of the brain in a mammal comprising: (a) removing a portion of a mammal's skull to expose a portion of the brain matter； and (b) contacting the exposed portion of the brain with a marking composition. Disclosed is a method for recording electrical activity in a brain, comprising: (a) removing a portion of the skull, thereby exposing a portion of a brain； (b) inserting an electrode into the brain； and (c) recording electrical activity via the electrode, wherein the electrode is at least partially coated with a marking composition.
