Preparation and characterization of hot-melt extruded polycaprolactone-based filaments intended for 3D-printing of tablets.

Hot-melt extruded (HME) filaments are an essential intermediate product for the three- dimensional (3D) printing of drug delivery systems (DDSs) by the fused deposition modelling (FDM) process. The aim of this study was to design novel polymeric 3D-printable HME filaments loaded with active pharmaceutical ingredients (APIs). The physical solid-state properties, mechanical properties, drug release and short-term storage stability of the filaments and 3D-printed DDSs were studied. Physical powder mixtures of polycaprolactone (PCL), plasticizer and API were manually blended, extruded by a single-screw extruder, and printed by a table-top FDM 3D-printing system. The composition of PCL and arabic gum (ARA) enabled the incorporation of 20%, 30% and 40% (w/w) of indomethacin (IND) and theophylline (THEO) into the HME filaments. The uneven distribution of API throughout the filaments impaired 3D printing. The HME filaments loaded with 20% IND or THEO were selected for the further analysis and printing tests (the ratio of PCL, ARA and IND or THEO was 7:1:2, respectively). The IND filaments were yellowish, mechanically strong and flexible, and they had a uniform filament diameter and smooth outer surface. The filaments containing THEO were smooth and off-white. The 3D-printed tablets fabricated from IND or THEO-loaded filaments showed sustained drug release in vitro. The drug release rate, however, significantly increased by changing the geometry of 3D-printed tablets from a conventional tablet structure to an unorthodox lattice ("honeycomb") structure. Overall, the combination of PCL and ARA provides an interesting novel polymeric carrier system for 3D-printable HME filaments and tablets.

Bi-Layered Polymer Carriers with Surface Modification by Electrospinning for Potential Wound Care Applications.

Polymeric wound dressings with advanced properties are highly preferred formulations to promote the tissue healing process in wound care. In this study, a combinational technique was investigated for the fabrication of bi-layered carriers from a blend of polyvinyl alcohol (PVA) and sodium alginate (SA). The bi-layered carriers were prepared by solvent casting in combination with two surface modification approaches: electrospinning or three-dimensional (3D) printing. The bi-layered carriers were characterized and evaluated in terms of physical, physicochemical, adhesive properties and for the safety and biological cell behavior. In addition, an initial inkjet printing trial for the incorporation of bioactive substances for drug delivery purposes was performed. The solvent cast (SC) film served as a robust base layer. The bi-layered carriers with electrospun nanofibers (NFs) as the surface layer showed improved physical durability and decreased adhesiveness compared to the SC film and bi-layered carriers with patterned 3D printed layer. Thus, these bi-layered carriers presented favorable properties for dermal use with minimal tissue damage. In addition, electrospun NFs on SC films (bi-layered SC/NF carrier) provided the best physical structure for the cell adhesion and proliferation as the highest cell viability was measured compared to the SC film and the carrier with patterned 3D printed layer (bi-layered SC/3D carrier). The surface properties of the bi-layered carriers with electrospun NFs showed great potential to be utilized in advanced technical approach with inkjet printing for the fabrication of bioactive wound dressings.