Composing drug delivery with light distribution improvement: the use of dissolving microneedles in skin cancer with photodynamic therapy

Significance: Dissolving microneedles (MN) have emerged as a promising platform for drug delivery, providing a minimally invasive approach to bypass the skin's natural barriers and enhance molecular penetration and diffusion. Their biocompatibility, user-friendly application, and ability to deliver precise therapeutic dosing make them particularly suitable for dermatological use. In addition to pharmacological benefits, dissolving MN possesses a geometric structure that enables optical waveguiding, thereby improving light penetration and distribution. Aim: We address a key limitation of photodynamic therapy (PDT): the limited penetration of light into biological tissues. PDT relies on activating photosensitizing agents with specific wavelengths of light to generate cytotoxic species, selectively targeting abnormal or diseased cells while minimizing effects on surrounding healthy tissue. Approach: Pyramidal dissolving MN arrays were fabricated from a biocompatible polymer and systematically characterized. Their light distribution profile under laser illumination was evaluated using image analysis. Results: Quantitative analysis of light distribution demonstrates that MN can simultaneously facilitate drug delivery and light distribution. Conclusions: This multifunctionality provides a synergistic therapeutic advantage, as localized drug release is complemented by optimized light delivery, thereby enhancing treatment outcomes. The dual-function platform has significant implications for PDT, enabling the design of integrated therapeutic systems that combine chemical and photonic modalities within a single, biodegradable device. Such systems may be particularly advantageous in resource-limited settings or outpatient care, where ease of use and effectiveness are essential. This strategy offers an approach to overcoming the limitations of conventional light-based therapies, supporting the development of more effective and accessible treatments for skin cancer and other dermatological conditions.