Microspicule-Assisted Skin Delivery: Mechanisms, Formulation Strategies and Therapeutic Potential

The stratum corneum acts as a strict rate-limiting barrier that limits the cutaneous penetration of large hydrophilic macromolecules and bio-actives exceeding 500 Da. While conventional topical vehicles often fail to deliver therapeutic concentrations into deeper skin layers for localized action, invasive microneedling modalities frequently cause post-treatment discomfort and structural trauma. To address these limitations, microspicules derived from marine and freshwater sponges (such as Haliclona sp. and Spongilla) have emerged as a promising physical penetration enhancement technology for targeted cutaneous treatments. When applied topically with a gentle massage, these microscopic, needle-like structures partially pierce the epidermis to form transient microchannels (30–60 µm deep), facilitating the controlled and sustained release of complex payloads like peptides, siRNA, and stem cell secretomes directly within the skin tissue. This review systematically evaluates the biological origins, mineral classifications, and distinct physical mechanisms of microspicule-assisted topical delivery. Furthermore, we analyze diverse formulation strategies ranging from conventional hydrogels to advanced niosome-liposome hybrid systems, while addressing critical variables like manufacturing reproducibility, microbial purification, and regulatory considerations for localized skin therapies. Ultimately, microspicule technology provides a highly biocompatible, efficient, and patient-acceptable platform for advanced topical drug delivery and cosmetology.