Graphene Oxide-Assisted Accumulation and Layer-by-Layer Assembly of Antibacterial Peptide for Sustained Release Applications

Fabrication of antibacterial materials with sustained release of active components is of great importance for long-term antibacterial applications. Graphene oxide (GO) has been found to be an excellent carrier for accumulating the antibacterial peptide of G(IIKK)4I-NH2 and mediating its loading into the layer-by-layer (LBL) films for sustained release applications. G(IIKK)4I-NH2 takes random coiled conformation in monomeric state below 0.17 mM but self-assembles into supramolecular aggregates with α-helical secondary structure at higher concentrations. It can bind onto GO surface in both monomeric and aggregate states to form stable GO@G(IIKK)4I-NH2 composites. Upon binding, the local amphiphilic environment of GO surface induces a conformational transition of G(IIKK)4I-NH2 monomers from random coils to α-helix. The aggregate binding enhances the loading amount greatly. GO (1 mg) can load as high as 1.7 mg of peptide at saturation. This enables the GO@G(IIKK)4I-NH2 composites to serve as reservoirs for sustained release of active G(IIKK)4I-NH2 monomers. Moreover, G(IIKK)4I-NH2 itself shows low efficiency in LBL assembly, whereas the GO@G(IIKK)4I-NH2 composites are ideal LBL assembling units with highly enhanced loading efficiency of G(IIKK)4I-NH2. The LBL films involving degradable poly(β-amino esters) can realize sustained release of G(IIKK)4I-NH2 for bacteria killing in a well-controlled manner. This study demonstrates an efficient strategy for fabrication of long-durable antibacterial materials and surface coatings by using GO as the carrier for drug accumulation and loading.