Advances in pharmaceutical technology have promoted the development of colon-targeted delivery system for oral administration of bioactive peptides or proteins to enhance their bioavailability. In this study, a multi-unit nanofiber mat was fabricated by coaxial electrospinning and its feasibility as the colon-targeted delivery system for a bioactive peptide, salmon calcitonin (sCT), was investigated. Sodium alginate and sCT-loaded liposome coated with pectin served as the shell layer and core layer, respectively. An in vitro study demonstrated that the encapsulated sCT was released in a sustained and colon-targeted way. Analysis using different mathematical models showed that release followed a complex mechanism. In addition, greater amounts of sCT were released from the core-shell nanofiber mat into simulated colon fluid (SCF) than was released from a uniaxial nanofiber mat (65.2% vs. 47.8%). The use of a core-shell nanofiber mat further alleviated the burst release of sCT into simulated gastric and intestinal fluid (SGF and SIF), demonstrating the superiority of a multi-unit vehicle for colon-targeted delivery of sCT. Furthermore, 88% of the bioactivity of encapsulated sCT was retained. This multi-unit vehicle offers a better-designed vehicle for the colon-targeted sustained release of bioactive peptides or proteins and, thus, should improve oral bioavailability. (C) 2019 Elsevier Inc. All rights reserved.