Development and analysis of a novel loading technique for FDM 3D printed systems: Microwave-assisted impregnation of gastro-retentive PVA capsular devices.

In this paper, we describe a modular post-printing loading protocol for a 3D printed gastro-retentive drug delivery system. Fused Deposition Modelling (FDM) 3D printing was exploited for the rapid prototyping of a modular floating system (caps-in-cap). Optimized models were produced as blank PVA scaffolds, and a morphological analysis of the FDM printed models was conducted to develop a straightforward protocol for drug-loading. The 3D printed gastro-retentive systems were then subjected to microwave irradiation in oversaturated solutions of anhydrous caffeine for drug loading, and research focused on an analysis of the impact of microwave irradiation on the chemical and physical properties of the polymer and the drug. The drug-loading efficiency, thermal and chemical characteristics of components, the stability of the drug and the morphology of processed printouts are characterised and described. Parameters of this unexplored microwave-assisted post-printing loading technique were evaluated and adequately set up, and the process resulted in the preservation of the polymeric matrix and enhancement of drug loading. Hence, microwave impregnation confirmed its potential in superseding the traditional pre- and post-printing loading methods, such as soaking techniques, being faster and more efficient and providing a new paradigm approach to personalised drug delivery.

Patient-specific 3D scanned and 3D printed antimicrobial polycaprolactone wound dressings.

The increasing prevalence of wound infections caused by antibiotic resistant bacteria is an urgent challenge facing modern medicine. To address this issue the expedient use of antimicrobial metals such as zinc, copper and silver were incorporated into an FDA-approved polymer (polycaprolactone - PCL) to produce filaments for 3D printing. These metals have broad-spectrum antimicrobial properties, and moreover, copper and zinc can enhance the wound healing process. 3D scanning was used to construct 3D models of a nose and ear to provide the opportunity to customize shape and size of a wound dressing to an individual patient. Hot melt extrusion was used to extrude pellets obtained by vacuum-drying of solutions of PCL and the different metals in order to manufacture metal-homogeneously-loaded filaments. Wound dressings with different shapes were produced with the filaments containing different concentrations of metals. Release of the metals from the dressings was determined by inductively coupled plasma atomic emission spectroscopy. All the different metal dressings show fast release (up to 24h) followed by slow release (up to 72h). The antibacterial efficacy of the wound dressings was tested using a thermal activity monitor system, revealing that silver and copper wound dressings had the most potent bactericidal properties. This study shows that 3D scanning and 3D printing, which are becoming simpler and more affordable, have the potential to offer solutions to produce personalised wound dressings.