Donepezil hydrochloride (DPL) and Embelin (EMB) loaded Nanostructured Lipid Carriers (NLCs) have been developed and optimized to achieve optimal drug loading, safer nasal delivery, effective neuronal/cell uptake, enhanced brain accessibility, controlled release, and desired therapeutic effect. Molecular docking studies demonstrated that both drugs bind effectively to AchE with interaction energies of -48.5319 and − 65.7525, respectively, indicating a synergistic approach. The hydrophobic interactions with target proteins facilitate the transportation of drugs through brain hydrophobic channels to provide a desired pharmacological response. N2a cell line investigation advised a 1:1 ratio of DPL and EMB to have the greatest possible synergistic effect based on the MTT assay. NLCs were fabricated by hot emulsification probe sonication method and optimized using QbD-based Central Composite Rotatable Design (CCRD). Optimized NLCs with a diameter of 180.2 nm were suitable for axonal uptake. A low Polydispersity index (PDI) score of 0.37 and Zeta Potential (ZP) of -12 mV indicated a uniform monodisperse system with persistent and stable dispersion properties. The NLCs demonstrated sustained drug release, DPL released at 90.72 ± 1.00%, and EMB at 81.30 ± 0.52% in 24 h. The Korsemeyer-Peppas model proved to be the most accurate fit due to its strong correlation. Ex vivo permeation and CLSM studies revealed superior goat nasal mucosa penetration of NLCs over suspension with a higher fluorescence level, up to 35 μm. NLCs treated nasal mucosa exhibited no erosion or interstitial gaps in the histopathological study. Moreover, NLCs were nontoxic and non-irritating, with a HET CAM score of 0.68 ± 0.05, indicating safe nasal delivery. The cellular uptake study showed a preponderance of the NLCs in the Cell’s cytoplasm, indicating ready uptake by N2a cells. Hence, intranasal therapy with the DPL and EMB-loaded NLCs could be a practical and promising implementation. Further in vivo, and clinical studies will be required to establish the formulation’s efficacy in treating Alzheimer’s disease (AD).

Graphical Abstract

盐酸多奈哌齐 (DPL) 和 Embelin (EMB) 负载的纳米结构脂质载体 (NLC) 已被开发和优化，以实现最佳的药物负载、更安全的鼻腔递送、有效的神经元/细胞摄取、增强的大脑可及性、控制释放和期望的治疗效果。分子对接研究表明，两种药物均能有效结合 AchE，相互作用能分别为 -48.5319 和 - 65.7525，表明存在协同作用。与靶蛋白的疏水相互作用促进药物通过脑疏水通道的运输，以提供所需的药理反应。根据 MTT 测定，N2a 细胞系研究建议 DPL 和 EMB 的比例为 1:1，以产生最大可能的协同效应。NLC 采用热乳化探针超声处理方法制造，并使用基于 QbD 的中央复合旋转设计 (CCRD) 进行优化。优化后的 NLC 直径为 180.2 nm，适合轴突摄取。0.37 的低多分散指数 (PDI) 和 -12 mV 的 Zeta 电位 (ZP) 表明均匀的单分散体系具有持久且稳定的分散特性。NLC 表现出持续的药物释放，24 小时内 DPL 释放率为 90.72 ± 1.00%，EMB 释放率为 81.30 ± 0.52%。由于相关性很强，Korsemeyer-Peppas 模型被证明是最准确的拟合。离体渗透和 CLSM 研究表明，NLC 的山羊鼻粘膜渗透性优于悬浮液，荧光水平更高，高达 35 μm。在组织病理学研究中，NLC 处理的鼻粘膜没有表现出侵蚀或间质间隙。此外，NLC 无毒、无刺激性，HET CAM 评分为 0.68 ± 0.05，表明鼻腔给药安全。细胞摄取研究显示 NLC 在细胞的细胞质中占优势，表明 N2a 细胞已准备好摄取。因此，使用 DPL 和 EMB 负载的 NLC 进行鼻内治疗可能是一种实用且有前景的实施方案。还需要进一步的体内和临床研究来确定该制剂治疗阿尔茨海默病（AD）的功效。

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