Inkjet printing of layer-by-layer assembled poly(lactide) stereocomplex with encapsulated proteins

Inkjet printing, a technique that precisely deposits liquid droplets in picoliter-volume ranges on a substrate, has received increased attention for its novelty and ability to produce functional materials. This technology is considered one of the most promising methods for the controlled deposition of different polymers. In our previous study, a poly(lactide) (PLA) stereocomplex was fabricated using inkjet printing on a substrate. The stereocomplex was formed by the layer-by-layer (LbL) stepwise deposition of poly(l-lactide) (PLLA) and poly(d-lactide) (PDLA). Multiple inkjet passes could conclusively improve the PLAs crystal structure with solvent evaporation (solidification) and dissolution of PLA. We suggested that this technique may also be applicable for fabricating polymer composites with drugs, such as peptides, proteins, and nanoparticles, which is incompatible with the PLA. Here, we report the utilization of this technique to create a PLA stereocomplex with drugs as a drug carrier/reservoir. The three components of PLLA, PDLA, and model drugs (an 8-mer peptide, ovalbumin, and protein-encapsulating nanoparticles) were alternately overprinted onto the substrate without an intermediate rinsing step. Inkjet printing was used successfully to form PLA stereocomplex composites with drugs by the LbL deposition of polymers and functioned as drug carriers/reservoirs. The sustained release of the drugs was observed from the PLLA/PDLA/drug composites. By varying the crystalline structure of PLAs-drug composites, the release kinetics of drugs could be altered and controlled efficiently. Moreover, a high drug loading content (wt %) of PLA stereocomplex composites was achieved up to 100 wt % loading, and the composites with 50 wt % of drug loading content were available for sustained-release formulation. This fabrication technique would provide a platform for creating protein/vaccine/gene delivery carriers with the desired release profiles by controlling the microphase-separated structure and drug distribution within the composites.