Allergen to asset: Pollen-based drug delivery systems

The rising demand for therapeutics, driven by aging populations and chronic diseases, challenges the pharmaceutical manufacturing of sustainable drug delivery systems. While development of microcarriers from natural sources such as plant or animal-sourced polymers and lipids show promise, the resource-intensive and complex processes involved limits their translatability and access. In this review, we discuss briefly the existing microcarriers fabricated from natural polymers and transition to recent efforts that have been devoted to exemplify pollen, traditionally regarded as an allergen, exhibits qualities that fit the criteria of a desirable microcarrier, and can be exploited to be valuable drug delivery assets with potential of encapsulating a wide spectrum of cargo and targeted conveyance. We scope through the various derivatives of pollen-derived microcarriers, especially highlighting the recent development of the soft pollen microgel variants, which was designed in alignment with the concept of Cross Economy of transforming abundant, low-value materials to create high-value products through easily portable, innovative and effective processing methods. We further discuss the future outlook of the pollen microgel and suggest aspects of pollen research that needs to be pursued to realize its translation to be a sustainable asset to drug delivery applications.