Localized gene delivery and enhanced cell-cell communication via bio-orthogonal polymer coatings

Surface modification of biomaterials, particularly by adding bioactive coatings, enhances cell-material interactions at the nanoscale, improving implant performance at the macroscale. One approach involves gene delivery via surface-bound coatings, allowing for controlled local release of viral particles. However, viral gene delivery systems, such as lentiviral vectors, face challenges in precision targeting and transduction efficiency. To address these, a bio-orthogonal coating was developed and used on titanium using chemical vapor deposition (CVD) polymerization. Co-presenting a cell-binding peptide and immobilized lentiviral particles on the surface of Ti increased gene delivery efficiency by directing cells to the surface, making them easier to transduce. Specifically, a poly[(4-(3,4dibromomaleimide)-p-xylylene)-co-(4-pentafluorophenol ester-p-xylylene)] coating was prepared using CVD polymerization on Ti discs as a bio-orthogonal layer to tether lentiviral particles delivering GJA1, the gene for the gap junction protein Connexin 43 (Cx43) and the Mesenchymal stem cell (MSC) binding peptide, DPIYALSWSGMA. The polymer coating exhibited high binding efficiency for both lentivirus and peptide, allowing for precise microcontact printing. Immobilized lentiviral transduction efficiency matched that in supernatant, with co-delivery increasing transduction efficiency by 35%. The biorthogonal coating boosted MSC binding 2.7-fold, leading to a density-dependent rise in cell-cell communication. High-density seeding enabled gap junction formation, while Cx43 transduction increased intercellular communication by 36%. In low-density culture, transduction led to an 84% increase in cell-cell communication within 4h of in vitro culture. This work presents a simple, repeatable surface modification method for biomolecular immobilization, combining engineered viral vectors and peptides to enhance gene delivery approaches.