Succinimidyl 3 2 pyridyldithio propionate spdp

The two microRNA mimics were provided by Integrated DNA Technology (IDT, Coralville, IA). The sequence of miR-4539 is 5′-S-S-GCUGAACUGGGCUGAGCUGGGC and the sequence of miR-4261 is 5′-S-S-AGGAAACAGGGACCCA. The 5′-end of the oligo was modified with disulfide capping to introduce a thiol group for conjugation with magnetic nanoparticles. The culture media, succinimidyl 3-(2-pyridyldithio)propionate (SPDP) and tris(2-carboxyethyl)phosphine (TCEP) were purchased from Thermo Fisher Scientific (Waltham, MA), while the fluorescent dye Cy5.5-NHS was purchased from GE Healthcare Life Sciences (Pittsburgh, PA). All antibodies for Western blotting were purchased from Abcam (Cambridge, MA). All other chemicals were purchased from Sigma-Aldrich (St. Louis, MO).

Cytochrome c from equine heart ≥ 95%, α-Lactalbumin from bovine milk, acetonitrile, ethanol, acetone, dimethylformamide (DMF), reduced glutathione ethyl ester, N,N-diisopropylethylamine (DIEA), tributhylphosphine (PBu3), and 3-nitro-2-pyridinesulfenyl chloride (Npys-Cl) were purchased from Sigma-Aldrich (St. Louis, MO, USA). Carboxylic PEG acid, mPEG-COOH (2000 Da), Folic acid PEG thiol, Folate-PEG-SH (2000 Da), and Folic acid-PEG-FITC (MW 3400 Da) were purchased from NanoCS (Boston, MA, USA). Folate-poly(ethylene glycol)-carboxylic acid FA-PEG-COOH (MW 3000 Da) and Poly(lactide-co-glycolide)-thiol end cap (Mn: 10,000–30,000 Da) were purchased from Akina, Inc. (West Lafayette, IN, USA). Succinimidyl-3-(2-pyridyldithio) propionate (SPDP) was obtained from Thermo Fisher Scientific (Waltham, MA, USA). Fluorescein isothiocyanate isomer I (FITC) was purchased from Sigma-Aldrich (St. Louis, MO, USA).