BSA	bovine serum albumin
MTX	methotrexate
DHF	dihydrofolic acid
DHFR	dihydrofolate reductase
MAL–(CH2)3–COOSu	maleimidopropionic acid-N-hydroxysuccinimide ester
GSSG	oxidized glutathione
BSA–S–S–MTX	BSA–S–MAL–(CH2)3–CONH–(CH2)2–S–S–(CH2)2–NHγCO–MTX
BSA–GSSG–MTX	BSA–S–MAL– (CH2)3–CONH–GSSG–NHγCO–MTX
BSA–(CH2)6–MTX	BSA–S–MAL–(CH2)3–CONH–(CH2)6–NHγCO–MTX
MALDI-TOF	matrix-assisted laser desorption ionization time of flight
ESMS	electrospray single quadruple mass spectroscopy
DCC	N,N′ dicyclohexylcarbodiimide
GSH	reduced glutathione
DMF	dimethylformamide
DIPEA	N,N′ diisopropylethylamine