the form of sodium chloride potassium chloride or any other salt compatible with cell growth and iii serum supplemented to a final concentration range of 30 90 volume volume or between 40 80 and iv a 5 or 6 carbon polyol such as xylitol arabitol or sorbitol in the concentration range of 5 mm 500 mm and preferably 250 mm the subject invention also concerns kits comprising in one or more containers reagents for practicing the present invention in one embodiment a kit can comprise an electroporation buffer of physiological ionic strength and ph and a serum or purified protein pre mixed in the buffer or provided separately from the buffer for addition thereto the serum provided can be sufficient for a final concentration in the buffer of any concentration from about 30 to about 95 v v a kit of the invention can also optionally include one or more osmolytes in one embodiment the osmolyte is a carbon polyol in a specific embodiment the osmolyte is a 5 or 6 carbon polyol in a more specific embodiment the carbon polyol is xylitol sorbitol arabitol maltitol glycerol erythritol mannitol isomalt or lactitol the kit can also optionally include agents for adjusting ionic strength and ph of the buffer such as hepes tris sodium phosphate compounds sodium salts potassium salts etc in another embodiment a kit of the invention can include one or more purified proteins for addition to the electroporation buffer the purified protein s provided can be sufficient for a final concentration of the protein in the buffer of any concentration.