Engineering large gelatin nanospheres coated with quantum dots for targeted delivery of human osteosarcoma with enhanced cellular internalization

Due to the special structures of cell membrane, good internalization is one of major concerns on using large nanospheres as carriers for labeling and treatment of cancer. We herein report fluorescent gelatin nanosphers (GNs) coated with CdSe/ZnS quantum dots (QDs) to form a viable vehicle for theranostic applications. Anti-human immunoglobulin G Fab formation, anti-IgG Fab, is bioconjugated on to the hybrid fluorescent GNs for targeted delivery (QDs-GNs-anti-IgG Fab). Human osteosarcoma cell line is used in studying the interaction between hybrid fluorescent GNs with and without anti-IgG Fab. The average particle size of the fluorescent GNs bioconjugated with antibodies is estimated at 480±50 nm. The emission (λem) of the fluorescent GNs is around 652 nm. The quantitative analysis on the surface modification and bioconjugation of GNs has been discussed in this paper. The three-dimensional z-stacking fluorescent images reveal that the hybrid GNs with anti-IgG Fab has ~1.5 times increase in internalization with human osteosarcoma cells than GNs without the antibody fragment. The improved cellular interaction of the QDs-GN-anti IgG Fab is attributed to the bioconjugation of antibodies which can provide specificity for targeted drug delivery. Relative cell viability (%) is larger than 80% for each type of functionalized GNs up to 40 μg/mL. We expect that the functionalized gelatin sphere can offer an effective theranostic tool for targeted drug delivery and direct imaging confirmation simultaneously.