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Over the decades, oral delivery of proteins and biological molecules has been puzzling scientists owing to the gastrointestinal barriers including the mucosal layer lining the entire gastrointestinal (GI) tract epithelium, the luminal pH, and enzymatic degradation that lead to poor bioavailability. The limited oral bioavailability of such molecules has prompted several attempts to develop a novel delivery system that can shift from subcutaneous to oral administration. Till now, there is no approved oral insulin dosage form available on the market. The needle-based delivery system has emerged as a promising strategy to combat these barriers by directly injecting the drug into the GI tract. The performance of microneedle technology mainly depends on the mechanical strength and the structure, including needle geometry, height, tip radius, and wall thickness. Also, it is crucial to pay attention to the behavior of the capsule inside the GIT by adjusting mucoadhesion characteristics and improving the localization of the capsule to the intestinal wall to avoid gastric obstruction.

Three-dimensional (3D) printing offers unique, rapid, and cost-effective manufacturing methods to print products with complex geometries and high resolution. Digital Light Processing (DLP) is one of the 3D-printing technologies with a significant capacity in terms of resolution, processing time, and efficiency over the other methods. However, the lack of commercially available resin that can be used in the manufacturing of oral dosage forms has been a challenge. To address this issue, we formulated a mucoadhesive photocurable resin using methacrylated chitosan as the mucoadhesive ingredients and BioMed resin as the resin matrix to print microneedle capsules targeting oral delivery. The 3D-printed capsule can be a promising carrier that mediate the transport of insulin and other biological drugs to successfully overcome gastrointestinal barriers and actively deliver the drug molecules into circulation.