Unityinova 500 nmr spectrometer

The synthetic route of poly(γ-GA-co-γ-DSGA) is illustrated in Figure 1a. To partially activate the γ-GA residues of poly(γ-GA) into the reactive γ-GAOSu moieties, NHS (50 mol % with respect to the γ-GA residues) and DCC (equal to molar concentration of NHS) used as the coupling agent were added to the solution of poly(γ-GA) in DMSO/pyridine (3/1 (v/v)). The reaction was carried out at 4°C for 48 h. The undesired product, N,N’-dicyclohexylurea (DCU), was then removed by the repeated filtration of the concentrated polymer solution. The partial transesterification of poly(γ-GA-co-γ-GAOSu) with distearin (25 mol% with respect to the original γ-GA residues in poly(γ-GA)) was then conducted at 60°C for 7 days, using 4-dimethylaminopyridine as the catalyst. This was followed by the dialysis (Cellu Sep MWCO 12000∼14000) against DMSO/THF (3/1 (v/v) solution) to eliminate the unreacted lipid species. Afterward, full hydrolysis of the remaining γ-GAOSu into the γ-GA residues was achieved by the addition of pH 7.4 tris buffer. The solution was then dialyzed (Cellu Sep MWCO 12000∼14000) against deionized water to remove NHS, DMSO and THF. Finally, the purified lipid/polypeptide conjugate was collected by lyophilization. The chemical composition was determined by ¹H-NMR (Varian Unityinova 500 NMR Spectrometer) using DMSO-d₆ as the solvent.

Epoxidized Soybean Oil (ESO) was obtained from Sankim (İstanbul, Turkey), maleic anhydride (MA), 2-chloroethanol (CE), 4-(dimethylamino)pyridine (DMAP), zinc chloride, hydroquinone, styrene (ST), sodium iodide, tetrahydrofuran (THF), triethylamine (TEA) were purchased from Merck (Darmstadt, Germany). All of these chemicals were used without any further purification. FTIR spectra of the compounds and copolymers were performed by Bruker Optics Vertex 70 spectrometer using ATR (attenuated total reflection) techniques from 4000 cm⁻¹ to 400 cm⁻¹. ¹H NMR spectra were acquired by a Varian Unity Inova 500 NMR spectrometer in CDCl₃. Thermal stabilities of the material were found by Shimadzu DTG 60 model TGA instrument with a 10 °C/min heating rate under nitrogen atmosphere. Differential scanning calorimetric (DSC) analyses of the copolymers were performed with a heat-flux type DSC instrument (SII Nanotechnology, ExStar 6200).