The molecular weight, LA/GA molar ratio and PLGA/PEG weight ratio of the copolymer were determined by means of proton nuclear magnetic resonance 1H NMR spectroscopy on a Bruker (Billerica, MA, USA) ADVANCE III HD 700 MHz instrument in deuterated chloroform (CDCl3) solvent at 25 °C (Supplementary Figure S1 ). The number-average molecular weight (Mn) and polydispersity index (Mw/Mn) of the PLGA–PEG–PLGA copolymer were determined via gel permeation chromatography with the multi-angle light scattering method (GPC-MALS) (Supplementary Figure S2 ). The instrumental setup included an Agilent HPLC 1100 Series instrument with a degasser, pump, autosampler, set of two PLgel 5 μm Mixed-C 300 × 7.5 mm columns (Agilent, Santa Clara, CA, USA) thermostated to 25 °C and a UV-VIS diode array detector connected to a DAWN HELEOS II multi-angle laser light scattering detector, a ViscoStar-II differential viscometer and Optilab T-rEX refractive index detectors (Wyatt Technology, Dernbach, Germany). Tetrahydrofuran was used as the mobile phase at a flow rate of 1 mL·min−1.
Dawn heleos 2 multi angle laser light scattering detector
Manufactured by Wyatt Technology
Sourced in United States
The DAWN HELEOS II is a multi-angle laser light scattering (MALS) detector. It measures the angular dependence of scattered light from macromolecules or particles in solution, which can be used to determine their molecular weight and size.
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Lab products found in correlation
Plgel 5 μm mixed c 300 7.5 mm columns, by Agilent Technologies (1 mentions)
Viscostar 2 differential viscometer, by Wyatt Technology (1 mentions)
Advance 3 hd 700 mhz, by Bruker (1 mentions)
Optilab t rex refractive index detector, by Wyatt Technology (1 mentions)
Optilab rex interferometric refractometer, by Wyatt Technology (1 mentions)
Sil 20ac ht, by Shimadzu (1 mentions)
Sb 805 hq, by Wyatt Technology (1 mentions)
Galaxie software, by Agilent Technologies (1 mentions)
Spectrum one spectrometer, by PerkinElmer (1 mentions)
Astra software, by Wyatt Technology (1 mentions)
3 protocols using dawn heleos 2 multi angle laser light scattering detector
1
Characterization of PLGA-PEG-PLGA Copolymer
2
Chitosan Characterization by SEC-MALS
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The average MW and polydispersity index (PDI) for chitosan samples were determined by size-exclusion chromatography (SEC) as described in Lavertu et al. [66 (link)]. Measurements were performed on a Gel Permeation Chromatography (GPC) system consisting of an LC-20AD isocratic pump (Shimadzu, Kyoto, Japan), an autosampler SIL-20AC HT (Shimadzu), an oven CTO-20AC (Shimadzu) coupled with a Dawn HELEOS II multiangle laser light scattering detector (Wyatt Technology Co., Santa Barbara, CA, USA), an Optilab rEX interferometric refractometer (Wyatt Technology Co.), and two Shodex OHpak columns (SB-806M HQ and SB-805 HQ) connected in series. The mobile phase was an acidic aqueous buffer (AcOH 0.15 M, AcONa 0.1 M, NaN3 0.4 mM, 0.1 M NaCl) and a chitosan dn/dc value of 0.205 was used (laser’s wavelength of 658 nm).
3
Characterization of Copolymer Composition and Molecular Weight
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1 H NMR spectra were obtained in CDCl3 using a Bruker Advance 300 or a Jeol 400 spectrometer and analysed using MestreNova software. Chemical shifts are recorded in ppm relative to residual CHCl3. The degree of polymerisation was determined by comparing integration of the vinyl protons of the HEMA end group with the integration of the methine signal of the lactide block or the methylene signal of the glycolide block.
Copolymer molecular weight was determined by gel permeation chromatography (GPC) using N,N-dimethylformamide (DMF) as a solvent containing 1% LiBr at a flow rate of 0.6 mL min -1 on a Varian Prostar instrument (Varian inc.) equipped with a Varian 325 UV-vis dual wavelength detector (254 nm), a Dawn Heleos II multiangle laser light scattering detector (Wyatt Technology Corp.), a Viscotek 3850 differential RI detector and a pair of PL gel 5 µm Mixed D 300 х 7.5mm columns with guard column (Polymer Laboratories Inc.) in series.
Near monodisperse polystyrene standards (Polymer Laboratories) were used for calibration.
Data analysis was achieved with Galaxie software (Varian Inc.) and chromatograms characterised with the Cirrus software (Varian Inc.) and Astra software (Wyatt Technology Corp.). ATR-FTIR spectra were recorded using a Spectrum One spectrometer (Perkin Elmer, Bucks. UK) at 4cm -1 resolution with 32 co-addition scans recorded between 600 and 4000 cm -1 .
Copolymer molecular weight was determined by gel permeation chromatography (GPC) using N,N-dimethylformamide (DMF) as a solvent containing 1% LiBr at a flow rate of 0.6 mL min -1 on a Varian Prostar instrument (Varian inc.) equipped with a Varian 325 UV-vis dual wavelength detector (254 nm), a Dawn Heleos II multiangle laser light scattering detector (Wyatt Technology Corp.), a Viscotek 3850 differential RI detector and a pair of PL gel 5 µm Mixed D 300 х 7.5mm columns with guard column (Polymer Laboratories Inc.) in series.
Near monodisperse polystyrene standards (Polymer Laboratories) were used for calibration.
Data analysis was achieved with Galaxie software (Varian Inc.) and chromatograms characterised with the Cirrus software (Varian Inc.) and Astra software (Wyatt Technology Corp.). ATR-FTIR spectra were recorded using a Spectrum One spectrometer (Perkin Elmer, Bucks. UK) at 4cm -1 resolution with 32 co-addition scans recorded between 600 and 4000 cm -1 .
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