# Novel Molecular Weight Gradient Hyaluronate Dissolving Microneedles for Sustained Intralesional Delivery and Photodynamic Activation of Hematoporphyrin in Port-Wine Stain Therapy

## TL;DR

This paper introduces a new microneedle system for targeted delivery of hematoporphyrin to treat port-wine stains, avoiding systemic side effects.

## Contribution

The study is the first to apply dissolving microneedles for localized, rapid delivery of hematoporphyrin in port-wine stain therapy.

## Key findings

- Microneedles with a molecular weight hyaluronate gradient dissolved in 30 minutes and delivered hematoporphyrin effectively.
- The system achieved high drug concentration and rapid release in skin lesions while avoiding systemic exposure.
- The design showed superior mechanical strength and drug loading capacity compared to traditional methods.

## Abstract

Port-wine stain (PWS), a progressive congenital vascular malformation characterized by ectatic dermal capillaries, demonstrates age-dependent lesion expansion and chromatic intensification, resulting in significant psychosocial comorbidity. While systemic hematoporphyrin (HP) administration remains the clinical paradigm for photodynamic therapy (PDT), its therapeutic utility is severely constrained by non-targeted biodistribution. Pharmacokinetic analyses reveal prolonged dermal retention and suboptimal lesion accumulation, predisposing 42% of patients to phototoxic reactions. To address these limitations, this work creatively suggested a local targeted drug delivery method based on soluble microneedles in response to the difficulties mentioned above. The rational design of a molecular weight (MW) HA gradient system enabled the engineering of ternary nanocomposite microneedles with enhanced biomechanical integrity (0.49 N/needle) and superior HP loading capacity, which collectively facilitated spatiotemporally controlled transdermal delivery of hematoporphyrin with complete dissolution within 30 min. The release performance, skin permeability, and storage stability of hematoporphyrin dissolving microneedles (HP-DMNs) have all been demonstrated in vitro. This study applies soluble microneedle technology to the delivery of HP in PWS for the first time. It avoids the risk of systemic exposure through precise local administration. It uses the rapid dissolution properties of microneedles to achieve high concentration and rapid release of drugs in skin lesions. This study provides a new strategy for sustained intralesional release and rapid drug delivery treatment of PWS and provides novel ideas for the development of new formulations of HP and related photosensitizers.