α cyano 4 hydroxycinnamic acid

BPA, trifluoroacetic acid (TFA), LC/MS grade acetonitrile (ACN), polyethylene glycol (PEG) 200 and PEG600, sodium trifluoroacetate (TFANa) were purchased from FUJIFILM Wako Pure Chemical Corporation (Osaka, Japan). 2,5-Dihydroxybenzoic acid (DHB) and α-Cyano-4-hydroxycinnamic acid (CHCA) was purchased from Tokyo Chemical Industry Co., Ltd. (Tokyo, Japan).

3-[Bis(dimethylamino)methyliumyl]-3H-benzotriazol-1-oxide hexafluorophosphate (HBTU), 1-hydroxybenzotriazole hydrate (HOBt·H₂O), triisopropylsilane (TIS), α-cyano-4-hydroxycinnamic acid (CHCA), Kaiser test kit (phenol/ethanol, ninhydrin/ethanol, potassium cyanide/pyridine), 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC), and N-hydroxysuccinimide (NHS) were purchased from Tokyo Chemical Industry (TCI, Tokyo, Japan). Dichloromethane (DCM) and N,N-dimethylformamide (DMF) were purchased from Nacalai Tesque Inc (San Diego, CA, USA). 1,2-Distearoyl-sn-glycero-3-phosphoethanolamine-N-[methoxy(polyethylene glycol)-2000] (DSPE-mPEG2000; DSPE-PEG) and egg L-α-phosphatidylcholine (PC) were purchased from Avanti Polar Lipid Inc. (Alabaster, AL, USA). In addition, cholesteryl hemisuccinate (CHEMS) was purchased from Sigma-Aldrich (St. Louis, MO, USA). Piperidine (PPD) was purchased from Watanabe Chemical Industries (Hiroshima, Japan).

The molecular masses of the peptides were determined by means of an AXIMA confidence spectrometer (SHIMADZU Co., Kyoto, Japan) in the positive ion mode [21 (link)]. Mass spectrometric analyses of peptides were carried out in the reflector mode using α-cyano-4-hydroxycinnamic acid (Tokyo Chemical Industry Co., Ltd., Tokyo, Japan) as a matrix. In a typical run, the lyophilized peptide (ca. 0.1 nmol) was dissolved in 0.05% TFA aq/50% CH₃CN (1 μL), mixed with 1 μL of a matrix solution (10 mg/mL), and air-dried on the sample plate for use in MALDI-TOF/MS.