DOPC Nanodisc. Nanodiscs of phospholipids may be used for scientific research involving membrane proteins or cell membranes. The DOPC nanodisc are prepared by solubilizing a liposome composed of DOPC : cholesterol : DSPE-PEG2000 (7.5 : 1 : 2.5) using styrene - maleic acid (SMA) copolymers. The SMA to lipid mass ratio is 8:1. After the liposome solubilization, the SMA 3:1 copolymer yields nanodiscs in an average diameter about 10 nm. The SMA 2:1 copolymer yields nanodiscs in an average diameter about 30 nm. The total lipid concentration is 5 mg/ml and the SMA copolymer concentration is 40 mg/ml. The nanodiscs are formed in a buffer composed of 10 mM Tris-HCl, pH 7.6. This product includes 2 ml of 5 mg/ml lipids composed of DOPC:Cholesterol: DSPE-PEG2000 and 40 mg/ml SMA copolymer 3:1 in 0.1 M TrisHCl, pH 7.6.