The Fabrication, Characterization, and Ulcerative Colitis Treatment of Colonic Targeting Microspheres Loading Baicalein Nanocrystals Based on the “Nano in Micro” Strategy

Introduction: Ulcerative colitis (UC) is a chronic inflammatory bowel disease with an increasing global incidence. Current clinical therapies are often limited by insufficient efficacy and adverse effects, highlighting the urgent need for safe and effective treatment strategies. This study aimed to develop a colon-targeted drug delivery system based on a “nano-in-micro” strategy for UC therapy. Methods: Baicalein nanocrystal microspheres (BE-NC MS) were prepared using an emulsification– internal gelation method. Their morphology, particle size, Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), and powder X-ray diffraction (XRD) were characterized. In vitro drug release behavior was evaluated. A dextran sodium sulfate (DSS)-induced UC model was established in C57BL/6 mice, and therapeutic efficacy was assessed after 7 days of treatment. Results: BE MS and BE-NC MS exhibited uniform particle sizes of 186.22 ± 0.69 μm and 185.49 ± 0.38 μm, respectively. The drug was effectively encapsulated and successfully delivered to the colon. Compared with baicalein (BE), baicalein nanocrystals (BE-NC), and (Baicalein microspheres) BE MS, BE-NC MS significantly alleviated UC symptoms and markedly reduced the levels of TNF-α, IL-1β, and IL-6 in colon tissue. Discussion: The enhanced therapeutic efficacy of BE-NC MS may be attributed to colon-specific delivery and improved bioavailability provided by the nano-in-micro formulation, enabling effective suppression of colonic inflammation. Conclusion: BE-NC MS represents a promising colon-targeted delivery system and offers a potential new strategy for the treatment of ulcerative colitis.