Polyhedral Oligomeric Silsesquioxanes‐Containing Conjugated Polymer Loaded PLGA Nanoparticles with Trastuzumab (Herceptin) Functionalization for HER2‐Positive Cancer Cell Detection

The synthesis of polyhedral oligomeric silsesquioxanes (POSS)‐containing conjugated polymer (CP) and the polymer loaded poly(lactic‐co‐glycolic‐acid) (PLGA) nanoparticles (NPs) with surface antibody functionalization for human epidermal growth factor receptor 2 (HER2)‐positive cancer cell detection are reported. Due to the steric hindrance of POSS, NPs prepared from POSS‐containing CP show improved photoluminescence quantum yield as compared to that for the corresponding linear CP encapsulated NPs. In addition, the amount of ‐NH₂ groups on NP surface is well‐controlled by changing the molar ratio of poly(lactic‐co‐glycolic‐acid)‐b‐poly(ethylene glycol) (PLGA‐b‐PEG‐NH₂) to PLGA‐OCH₃ during NP formulation. Further conjugation of the NH₂‐functionalized CP NPs with trastuzumab (Herceptin) yields NPs with fine‐tuned protein density. These NPs are able to discriminate SKBR‐3 breast cancer cells from MCF‐7 breast cancer cells and NIH/3T3 fibroblast cells both on substrate and in suspension by taking advantage of the specific binding affinity between trastuzumab and HER2 overexpressed in SKBR‐3 breast cancer cell membrane. The high quantum yield and fine‐tuned surface specific protein functionalization make the POSS‐containing CP loaded NPs a good candidate for targeted biological imaging and detection.