Biofabrication of 3D cell-encapsulated tubular constructs using dynamic optical projection stereolithography.

It has been widely recognized that one of the critical limitations in biofabrication of functional tissues/organs is lack of vascular networks which provide tissues and organs with oxygen and nutrients. Biofabrication of 3D vascular-like constructs is a reasonable first step towards successful printing of functional tissues and organs. In this paper, a dynamic optical projection stereolithography system has been implemented to successfully fabricate 3D Y-shaped tubular constructs with living cells encapsulated. The effects of operating conditions on the cure depth of a single layer have been investigated, such as UV intensity, exposure time, and cell density. A phase diagram has been constructed to identify optimal operating conditions. Cell viability immediately after printing has been measured to be around 75%. Post-printing mechanical properties, swelling properties, and microstructures of the gelatin methacrylate hydrogels have been characterized. The resulting fabrication knowledge helps to effectively and efficiently print tissue-engineered vascular networks with complex geometries.

Digital light processing (DLP) 3D-printing technology and photoreactive polymers in fabrication of modified-release tablets.

In this study, we assessed the feasibility of using digital light processing (DLP) 3D printers (3DP) in fabrication of solid oral dosage forms. The DLP technology uses a digital micromirror device (DMD) that reflects and focuses ultraviolet (UV) light on the surfaces of photoreactive materials that polymerize in a layer-by-layer fashion. Using poly(ethylene glycol) diacrylate (PEGDA) and poly(ethylene glycol) dimethacrylate (PEGDMA) as photoreactive polymers and theophylline as a model drug, we deployed a DLP printer to fabricate tablets. After optimizing various printing parameters including UV intensity and exposure time, layer thickness, and polymer concentration, we printed various types of tablets with and without perforation. We then assessed the tablets for drug content, mechanical strengths, swellability, weight variation, microscopic features, drug-polymer interactions and drug release profiles. The loading of theophylline was 1%, which was independent of tablet weights. The drug content and weight variation were within the acceptable range, as recommended by the United States Pharmacopeia (USP). Scanning electronic microscopic (SEM) pictures showed tablets with distinct layers and smooth outer surfaces. The spectral scans, obtained using Fourier Transform Infrared Spectroscopy (FTIR), showed no chemical interactions between the drug and polymers. Similarly, drug content determined using a UV spectrophotometer was the same as that determined by a high performance liquid chromatography (UPLC). The extent of drug release increased with the increase in the number of perforations in the tablets. Overall, this study demonstrates that DLP 3DP can be used as a platform for fabricating oral tablets with well-defined shapes and different release profiles.