4 imidazolecarboxylic acid

Acrylic acid (AA), N,N,N’,N’-tetramethylethylenediamine (TMEDA), acrylate PEG (APEG; 480 Da), bisacrylamide (BAA), 1-vinylimidazole (VI), and ammonium persulfate (APS) were purchased from ThermoFisher Scientific (Fitchburg, WI, USA). acrylate PEG-NH₂ (APEG-NH₂; 2 kDa) was acquired from JenKem Technology (Allen, TX, USA). 4-Imidazolecarboxylic acid, all-trans-retinoic acid (ATRA), N-(3-aminopropyl)methacrylamide hydrochloride (APMA), and N,N’-bis(acryloyl)cystamine (BACA) were obtained from Sigma-Aldrich (St. Louis, MO). acrylate PEG-Mal (APEG-Mal; 2 kDa) was purchased from Creative PEGWorks (Chapel Hill, NC). Cell penetrating peptide (CPP), TAT-Cys (CYGRKKRRQRRR), was synthesized by Genscript (Piscataway, NJ).

Boltron® H40 (a hyperbranched polyester with 64 hydroxyl terminal groups; M_n: 2833 Da) was kindly provided by Perstorp Polyols Inc., USA, and purified by fractional precipitation in acetone and tetrahydrofuran (THF). β-Benzyl L-aspartate N-carboxyanhydride (BLA-NCA) was prepared as previously reported by our lab [49 (link)]. The heterobifunctional poly(ethylene glycol) (PEG) derivatives, methoxy–PEG–NH₂ (CH₃O-PEG–NH₂, M_n = 5 kDa) and maleimide–PEG–NH₂ (Mal–PEG–NH₂, M_n = 5 kDa), were purchased from JenKem Technology (Allen, TX, USA). Cy5 dye was obtained from Lumiprobe Corporation (Hallandale Beach, FL, USA). GE11 peptide (YHWYGYTPQNVIGGGGC) was synthesized by Tufts University Core Facility (Boston, MA, USA). GFP-siRNA-Cy5.5, GFP-siRNA, dimethyl sulfoxide (DMSO), 2-carboxybenzylaldehyde, 2-aminoethyl disulfide, 4-imidazolecarboxylic acid, and stannous (II) octoate (Sn(Oct)₂) were purchased from Sigma–Aldrich (St. Louis, MO, USA). 4-Dimethylamino pyridine (DMAP) and 1,3-dicyclohexylcarbodiimide (DCC) were purchased from ACROS and used without further purification. Other reagents, including RNAiMAX, were purchased from Thermo Fisher Scientific (Fitchburg, WI, USA) and used as received unless otherwise stated.

β-Benzyl l-aspartate N-carboxyanhydride (i.e., BLA-NCA) was prepared as previously reported.^{31 (link)} Methoxy–PEG–NH₂ (PEG–NH₂, M_n = 5 kDa) was obtained from JenKem Technology (Allen, TX). 4-Imidazolecarboxylic acid was obtained from Sigma–Aldrich (St. Louis, MO). The sNLS-Cas9-sNLS was obtained from Aldevron (Madison, WI). The NLS peptide (amino acid sequence: PKKKKRKV) was synthesized by Abi Scientific Inc. (Sterling, VA). Other reagents were obtained from Thermo Fisher Scientific (Fitchburg, WI).