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We present the synthesis of a modular delivery system that is composed of two main macromolecular building blocks, dendritic molecular transporter molecules and a polymeric scaffold in a size dimension of 5-10 nm. The conjugated dendritic molecular transporter units proved to be critical for the delivery of the polymer nanoparticle into 3T3 cells and illustrates the dendritic molecular transporter promoted intracellular uptake of polymer particles derived from intramolecular chain collapse processes. In a sequence of modification steps, pyridinyldithio linker was introduced to undergo thiol-disulfide exchange reactions with peptide sequences containing cysteine amino acid units to furnish peptide-nanoparticle conjugates with cleavable disulfide linkers. The intracellular uptake of the nanoparticle conjugates and the delivery of the peptidic cargo were studied via dual labeling of the nanoparticle with Alexa Fluor 568 dye and fluorescein (FITC) markers on the peptide in mammalian cell lines such as NIH 3T3 cells via confocal microscopy. In this work, we have demonstrated the assembly of a novel nanoscopic delivery system in which the conjugated dendritic molecular transporter molecules facilitated the rapid cellular uptake of a nanoparticle-peptide conjugate with up to 25 copies of peptidic cargo to establish new venues for the implementation of protein and oligonucleotide drugs.

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Size scale plays an important role in the release properties and cellular presentation of drug delivery vehicles. Because negatively charged chondroitin sulfate (CS) is capable of electrostatically sequestering positively charged growth factors, CS-derived nanoscale micelles and microscale spheroids were synthesized as potential growth factor carriers to enhance differentiation of stem cells. Particles were characterized for morphology, size distribution, surface charge, cytocompatibility, as well as release of transforming growth factor-β1 (TGF-β1) and tumor necrosis factor-α (TNF-α). CS micelles were spherical and negatively charged with a bimodal distribution of 324.1 ± 8.5 nm and 73.2 ± 4.4 nm diameters, and CS microspheres possessed a rounded morphology and a diameter of 4.3 ± 0.93 μm. Positively charged TGF-β demonstrated minimal release after loading in CS microspheres, while negatively charged TNF-α exhibited substantial release over the first 15 hours, suggesting TGF-β1 electrostatically complexed with CS. The micelles and microparticles were found to be cytocompatible at moderate concentrations with marrow stromal cell (MSC) monolayers and within embryonic stem cell (ESC) embryoid bodies. These synthesis techniques, which allow the formation of CS-based carriers over a variety of nano-and microscale sizes, offer versatility for tailored release of positively charged growth factors and controlled CS presentation for a variety of stem cell-based applications in tissue engineering and regenerative medicine.