Materials

Poly(D,L-lactide-co-glycolide) (65/35), dimethyl formamide (DMF), dimethyl sulfoxide (DMSO), di-isopropylethylamine (DIPEA), methanol, and ether were purchased from Sigma-Aldrich (St. Louis, MO). PVA [Poly(vinyl alcohol); Mw 25,000] was purchased from Polysciences (Warrington, PA). Poly(D,L-lactide-co-glycolide) (50/50) with terminal methoxy groups (PLGA-mPEG) or terminal n-hydroxysuccinimide groups (PLGA-PEG-NHS) (each with MW 20,000:5,000 Da, PLGA:PEG) were purchased from Akina (West Lafayette, IN). AXT050,^28,29 AXT051 (AXT050 analog where the last amino acid residue is swapped from a F to a W to enable stronger intrinsic fluorescence), biotinylated AXT050, and AXT050-IRD800 were custom synthesized and ordered from New England Peptide (Gardner, MA). Human recombinant integrin was purchased from R&D Systems (Minneapolis, MN). IRDye 800 CW was purchased from LI-COR (Lincoln, NE). Tissue culture reagents and cell lines were purchased from Lonza (Portsmouth, NH). Biological buffers were purchased from Fisher Scientific (Hampton, NH).