Isopentane pre-cooled with liquid nitrogen is generally considered the best method for freezing brain tissue for protein analysis:
Steps:Pre-cool isopentane in a metal or thick glass container by placing it in a bath of liquid nitrogen or on dry ice until it reaches a slushy consistency. Immediately immerse the freshly isolated brain in the pre-cooled isopentane for a few minutes until it is thoroughly frozen. Transfer the frozen brain to a pre-cooled container and store it at -80°C.
This method balances rapid freezing with minimized risk of ice crystal damage and tissue cracking, ensuring the best preservation of proteins for subsequent ELISA analysis.