Trimethylolpropane tris 3 mercaptopropionate

The branched thiol crosslinkers such as pentaerythritol tetrakis(3-mercaptopropionate) (>95%), trimethylolpropane tris(3-mercaptopropionate) (≥95.0%), and linear thiol 1,6-hexanedithiol (96%) were purchased from Sigma Aldrich. Darocur 1173® (2-hydroxy-2-methyl-1-phenyl-propan-1-one) purchased from Ciba Specialty Chemicals Inc. (Switzerland) was added as a liquid photoinitiator to the viscous prepolymer mixture. Various molar ratios of the multi-thiols were added to match the alkene bonds flanking the diallyl diurethane prepolymer. For instance of NIPU:100%_4SH, the mol ratio between diurethane (diene) and pentaerythritol tetrakis(3-mercaptopropionate) (4 thiols, 4SH) was 1:0.5. Meanwhile NIPU:50%_4SH-0%_3SH-50%_2SH were prepared from 1:0.25:0.5 ratio of diurethane (diene)_, pentaerythritol tetrakis(3-mercaptopropionate) (4 thiols, 4SH) and 1,6-hexanedithiol (2 thiols, 2SH), thus two thiol compounds contributed equally.
Each mixture was heated to 78°C for 5 min. After heating, Darocur 1173® was added to each mixture at (2% v/v) and periodically vortexed for an additional 5 min at 78°C.

All materials were used as supplied. Citrate-stabilized gold colloid suspensions (5 nm and 50 nm) and citrate stabilized silver colloid suspensions (40 nm) were purchased from Ted Pella. Phenol free-RPMI 1640 media, DMEM media without sodium pyruvate, and 10x PBS (without magnesium and calcium) were purchased from Life Technologies. DMEM media containing sodium pyruvate (ATCC 30–2002), DMEM-F12 media (ATCC-30–2006), AML-12 cells (ATCC CRL-2254), MDA-MB-231 cells (ATCC HTB-26), and RAW 264.7 cells (ATCC TIB-71) were purchased from ATCC. PEG-Maleimide was purchased from Nanocs. Pentaerythritol tetrakis (3-mercaptopropionate) and PEG-SH purchased from Sigma were handled under nitrogen at all times. Trimethylolpropane tris(3-mercaptopropionate) was purchased from Sigma and handled under nitrogen at all times. NOTE: If TTMP or PTMP is exposed to air and then used to synthesize particles, the size of those particles cannot be accurately predicted.