Desk 5 sputter system

Size and Zeta Potential Measurements: aNP size and zeta potential were measured using Zetasizer Nano: Malvern Zen 3600 Zetasizer. 0.1 mg of particles were added to 1 mL of filtered Millipore water, allowed to swell for 6 hours, and then measured. BSA loading: Amount of BSA per mg of aNP was measured using the Micro BSA Protein Assay Kit (ThermoFisher). Briefly, nanoparticles were suspended in Millipore water at a concentration of 0.1 mg/mL and added to an equal volume of working solution. After 2 hours of incubation at 37˚C, the suspension was centrifuged, and the supernatant removed for analysis. For the analysis, BSA-coated PLGA nanoparticles were compared to blank uncoated PLGA nanoparticles, and BSA-coated Nile Red-loaded PLGA nanoparticles were compared to Nile Red-loaded uncoated PLGA nanoparticles as some of the Nile Red was released from the nanoparticles during the incubation period. SEM: Vacuum dried nanoparticles were coated with 10 nm of gold using the Denton Desk V Sputter system. Particles were imaged with FEI Quanta 400 ESEM FEG using 10 kV.

Lyophilized
peptide was dissolved in Milli-Q water
to make a 2% by weight solution. A total of 125 μL of this solution
was mixed with 125 μL of 2× Dulbecco’s phosphate-buffered
saline (DPBS; Life Technologies) to form a 1% by weight hydrogel.
The 100 μL aliquots of the resulting hydrogel were allowed to
sit overnight at 4 °C. The samples were then dehydrated using
a 30% ethanol to 100% ethanol gradient over a 9 h time period. The
dehydrated hydrogels were then critical point dried using a critical
point drier (Electron Microscopy Sciences EMS 850). The dried samples
were attached to SEM pucks using conductive carbon tape and sputter
coated with 7–8 nm of gold using a Denton Desk V Sputter system.
All samples were imaged using a JEOL 6500F scanning electron microscope.