Iron salts

All chemicals used for SPIO synthesis, including iron salts and 15−25 kDa dextran, were purchased from Sigma-Aldrich (Saint Louis, MO). Purified human complement component C3 and iC3b was purchased from Quidel Corporation (San Diego, CA), aliquoted and stored at −80 °C. Goat anti-human complement C3 polyclonal antibody that recognizes most of the C3 cleavage products was purchased from MB Biomedicals (Solon, OH). A C5a ELISA kit was purchased from Sino Biological Inc. (Beijing, China) and used according to the manufacturer’s instructions. IRDye 800CW-labled secondary antibody (anti-goat) was from LI-COR Biosciences (Lincoln, NE). Feraheme, LipoDox, and Onivyde were obtained from the University of Colorado Hospital’s pharmacy. Human sera (total 47 donors) were obtained within a 2 week period from consented healthy donors at the University of Colorado Blood Donor Center (under the Center’s Institutional Review Board protocol for anonymous collection; only age and gender were made available to the investigators), according to the previously described protocol.^{43 (link)} Briefly, blood was collected into Vacutainer Z (Beckton Dickinson), left to clot for 1 h at room temperature, and then centrifuged at 2500g for 15 min to separate serum from blood clots. Serum was aliquoted and stored at −80 °C. Each aliquot was thawed and frozen no more than twice.

Iron salts were purchased from Sigma-Aldrich (St. Louis, MO, USA). DSPE-PEG3400-amine was from Laysan Bio. Bovine serum albumin was from Sigma (St. Louis, MO, USA). Methyltetrazine (MTZ)-PEG₄-NHS ester, trans-cyclooctene (TCo)-PEG₄-NHS ester, and MTZ-NHS ester were from Click Chemistry Tools (Scottsdale, AZ, USA). IRDye 800CW-NHS ester was from Li-COR Biosciences (Lincoln, NB, USA). Purified human IgG was from Jackson ImmunoResearch (West Grove, PA, USA). Zeba desalting columns (7 and 40 kDa) were from Thermo Fisher. Cy7-NHS ester and Cy3-NHS ester were from Lumiprobe Inc. (Hunt Valley, MD, USA). Goat anti-human IRDye 680 antibody was from Li-COR. Lipophilic carbocyanine dye DiOC18(7) (“DiR”) was from Thermo Fisher.

All chemical reagents used for nanoparticle synthesis, including iron salts and 15–25-kDa dextran, were purchased from Sigma-Aldrich (St Louis, MO, US). Cell culture media were purchased from Corning Life Sciences. Antidextran DX-1 antibody was purchased from StemCell Technologies (Vancouver, BC, Canada). Goat antimouse and goat antihuman complement C3 polyclonal antibodies were purchased from MP Biomedicals (Solon, OH). Mouse monoclonal antiproperdin antibodies were purchased from Quidel (San Diego, CA). All fluorescent secondary antibodies for immunostaining were from Thermo Fisher Scientific. Copper grids (300 mesh) were purchased from Electron Microscopy Sciences (Hatfield, PA, US). BALB/c mice were bred in an animal vivarium at the University of Colorado Denver Anschutz Medical Campus according to the IACUC approved breeding protocol. The BALB/c breeder mice were purchased from Charles River Laboratories International, Inc. (Wilmington, MA). C3^−/− mice (B6;129S4-C3^tm1Crr/J) were obtained from Dr. Holers and bred in house. C57BL6 mice (Charles River) were used as a control for knockout experiments.