Itaconic anhydride

Calcium chloride (CAS 10043-52-4), trisodium phosphate (CAS 7601-54-9), sodium hydroxide (CAS 1301-73-2), and itaconic anhydride (CAS 2170-03-8) were procured from Sigma Aldrich, Germany. Calcium glutamate (CAS 19238-49-4) was obtained from BenchChem, United States, and ascorbic acid (CAS 50-81-7) was procured from Enola, Latvia.

Crotonic anhydride (CA),
itaconic anhydride (IA), methacrylic anhydride (MA), type A gelatin
from porcine skin (gel strength ∼175 g Bloom), benzalkonium
chloride (BAC), deuterium oxide, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium
bromide (MTT reagent), fluorescein sodium salt (NaFl), glutaraldehyde
solution (25% in H₂O, grade II), glycine, 1 M hydrochloric
acid solution, sodium bicarbonate, sodium dodecyl sulfate (SDS), 2,4,6-trinitrobenzenesulfonic
acid (TNBSA, 5% in H₂O), and trypan blue (0.4% solution)
were purchased from Sigma-Aldrich (Gillingham, U.K.). Dimethyl sulfoxide
(DMSO), Dulbecco’s modified eagle medium (DMEM), fetal bovine
serum (FBS), penicillin-streptomycin (10000 U/mL), phosphate-buffered
saline (PBS) tablets (which were used to make 100 mL of 1× PBS
solution in deionized water, pH 7.40), sodium hydroxide, and trypsin-EDTA
(0.25% solution) were purchased from Fisher Scientific (Loughborough,
U.K.). All other chemicals were of analytical grade and used without
further purification. Dialysis tubing with a molecular weight cutoff
of 12–14 kDa was purchased from Medicell Membranes Ltd. (London,
U.K.). Deionized water was used throughout the experiments involving
aqueous solutions.

All reagents and solvents were used without further purification, otherwise indicated.
For polymer synthesis: Diethyl ether was distilled from sodium/benzophenone ketyl. Toluene and dichloromethane were distilled from calcium hydride under a nitrogen atmosphere. All reactions involving air- or water-sensitive compounds were routinely conducted in glassware flame-dried under a positive pressure of nitrogen or argon. Itaconic anhydride, tin(II) 2-ethylhexanoate, and D,L-lactide were purchased from Sigma-Aldrich Chemical Co.
For polymer nanoparticle preparation and degradation: Salts were purchased from Sigma-Aldrich. Organic solvents were commercial analytical grade. Deionized (DI) water was taken from the PURELAB Ultra ELGA purification system. For the NMR experiments, the deuterated solvents were deuterium oxide (D₂O) and deuterated trichloromethane from Innova-Chem, +99.8 atom D %.