One important limitation of topical photodynamic therapy (PDT) is the limited tissue penetration of precursors. Microneedles (MNs) are minimally invasive devices used to promote intradermal drug delivery. Dissolving MNs contain drug‐associated to polymer blends, dissolving after insertion into skin, allowing drug release. This study comprises development and characterization of a pyramidal model of dissolving MNs (500 μm) prepared with 5% wt/wt aminolevulinic acid and 20% wt/wt Gantrez AN‐139 in aqueous blend. Protoporphyrin IX formation and distribution were evaluated in tumor mice model by using fluorescence widefield imaging, spectroscopy, and confocal microscopy. MNs demonstrated excellent mechanical resistance penetrating about 250 μm with minor size alteration in vitro, and fluorescence intensity was 5‐times higher at 0.5 mm on average compared to cream in vivo (being 10 ± 5 a.u. for MNs and 2.4 ± 0.8 a.u. for cream). Dissolving MNs have overcome topical cream application, being extremely promising especially for thicker skin lesions treatment using PDT.

中文翻译：

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溶解含氨基乙酰丙酸的微针可改善原卟啉IX的分布

局部光动力疗法（PDT）的一个重要限制是前体的组织穿透力有限。微针（MNs）是用于促进皮内药物输送的微创设备。可溶性MN含有与聚合物共混物相关的药物，在插入皮肤后会溶解，从而释放药物。这项研究包括溶解和混合MNs（500μm）的金字塔模型的开发和表征，MNs用5％wt / wt的氨基乙酰丙酸和20％wt / wt的Gantrez AN‐139在水性混合物中制备。通过使用荧光宽视野成像，光谱学和共聚焦显微镜在肿瘤小鼠模型中评估原卟啉IX的形成和分布。MNs表现出优异的机械阻力，穿透力约为250μm，体外尺寸变化较小，荧光强度为0时高5倍。与体内乳膏相比平均为5毫米（MNs为10±5 au，乳膏为2.4±0.8 au）。可溶性MNs已经克服了局部乳膏的应用，特别是对于使用PDT治疗较厚的皮肤病变而言，具有极大的发展前景。