Microalgae Microneedle Supplies Oxygen for Antiphotoaging Treatment.

UV exposure often triggers photoaging of the skin. Pharmacological treatment suffers from severe side effects as well as poor efficacy because of insufficient skin penetration. Dissolved oxygen has been previously shown to reverse photoaged skin; however, the treatment is often limited by the availability of equipment (e.g., high-pressure oxygen). Poor oxygen diffusion into the skin has also limited its therapeutic efficacy. Herein, we developed a microneedle patch to deliver living microalgae to the deeper layers of the skin for efficient oxygenation and reversal of photoaging. The continuous release of oxygen from microalgae in the skin through photosynthesis reversed the inflammatory microenvironment and reduced reactive oxygen species levels in the photodamaged skin, leading to collagen regeneration and reduced wrinkles. This study provides not only a means for highly efficient skin oxygenation and reversal of photoaging but also an important theoretical basis for the clinical treatment of photoaging.