Nose-to-brain (N2B) delivery is a promising noninvasive strategy to circumvent the blood‒brain barrier (BBB). However, the clinical translation of N2B platforms remains hindered by a conceptual oversimplification that equates crude central nervous system (CNS) exposure with effective therapeutic delivery. This review reconceptualizes the N2B pathway as a stage-resolved sequential transport cascade extending from nasal entry to meaningful parenchymal and cellular access. We identify a critical imbalance in current formulation strategies, which have advanced two extreme poles, namely initial mucosal retention and epithelial permeation at one end and final target-cell engagement at the other, while leaving the intermediate post-epithelial gateways, including cerebrospinal fluid (CSF) and perivascular space (PVS)-mediated redistribution and deep intraparenchymal diffusion, as structural and interpretive blind spots. To bridge this gap, we propose an integrated engineering paradigm with three core design principles. First, multistage-aware design harmonizes sequential spatiotemporal functionalities within a single vehicle architecture. Second, disease-informed design integrates pathologically remodeled barrier states and glymphatic hydrodynamics into the formulation rationale. Third, cargo-informed design establishes the distinct biophysical identity and inherent liabilities of each payload, from small molecules to viral vectors and CRISPR machinery, as the primary engineering starting point. Finally, we advocate for a methodological standard demanding stage-specific validation of vehicle integrity, cross-boundary penetration, and functional target engagement, beyond compartment-blind whole-brain readouts. We further underscore the biofate and clearance of delivery systems as an emerging axis of safety and regulatory evaluation. Collectively, this framework provides a systematic basis for transitioning N2B engineering into a viable clinical modality.

Polydeoxyribonucleotide (PDRN) is a bio-derived therapeutic agent known to exhibit regenerative, angiogenic, and anti-inflammatory effects. However, its relatively large molecular size limits penetration across the skin barrier, thereby reducing the feasibility of noninvasive transdermal delivery. Iontophoresis is a promising approach for enhancing the transport of charged macromolecules, yet quantitative understanding of PDRN iontophoresis remains limited. Here, we present an in silico framework for cathodal PDRN iontophoresis based on the Nernst-Planck equation, focusing on passive diffusion and electromigration. The PDRN diffusion coefficient was determined from Franz diffusion cell experiments using the lag-time method, and the effective charge was estimated from prior experimental reports on dsDNA. A three-layer skin model comprising the stratum corneum, epidermis, and dermis was employed, and PDRN transport was analyzed as a function of applied current density, initial PDRN concentration, delivery time, and PDRN diffusion coefficient. Transport was quantified using molar flux and cumulative permeation at the epidermis-dermis interface and mid-dermis. The results clarify parameter-dependent regulation of delivery and reveal a depth-dependent shift in the dominant transport mechanism, highlighting the importance of iontophoresis for macromolecular delivery. Using calibrated outputs, we assessed agreement with experimental permeation data using the root-mean-square deviation (RMSD), mean absolute percentage error (MAPE), and the coefficient of determination (R[2]). Overall, this work provides a computational baseline to predict PDRN iontophoresis outcomes and proposes practical iontophoresis strategies for PDRN to guide device design.

Pancreatic ductal adenocarcinoma (PDAC) remains one of the most lethal solid tumors due to its dense desmoplastic stroma, poor vascular perfusion, and the limited intratumoral delivery of chemotherapeutic agents such as oxaliplatin (OXA). Extracellular vesicles (EVs) offer a biocompatible platform for drug delivery, yet their intrinsic lack of tumor specificity constrains therapeutic efficacy. Ephrin type-A receptor 2 (EphA2), which is highly expressed and efficiently internalized in PDAC, represents an attractive molecular target for guiding EVs into tumor cells. In this study, we engineered HEK293T-derived EVs to display membrane-anchored anti-EphA2 Fab fragments and encapsulate OXA (EVs-EphA2/OXA) as a targeted delivery system for PDAC therapy. Stable producer cells expressed the engineered Fab on the plasma membrane and released vesicles that retained canonical EV markers and robust antigen-binding capability. EVs-EphA2 demonstrated selective uptake into EphA2-positive AsPC-1 and BxPC-3 cells and induced significantly greater cytotoxicity than free OXA or untargeted EVs/OXA in vitro. In xenograft models, EVs-EphA2/OXA achieved the most pronounced tumor suppression, accompanied by increased γH2AX-associated DNA damage, enhanced TUNEL-positive apoptosis, and preferential tumor accumulation in biodistribution imaging. These findings demonstrate that EphA2-targeted EVs can substantially improve intratumoral delivery of OXA and amplify antitumor efficacy, supporting EVs-EphA2/OXA as a promising platform for receptor-guided chemotherapy in PDAC.

Pulmonary protein delivery has proven to be an effective approach for the treatment of local and systemic diseases, and particles that can be efficiently inhaled into peripheral regions should possess aerodynamic sizes of <2 µm, for which nano-spray-drying (NSD) is a powerful tool for fabrication. However, NSD powders have a high specific surface area and surface energy, which causes severe agglomeration and poor aerosolization performance. To solve these problems, cyclodextrin/leucine delivery systems were constructed, which can evidently protect alkaline phosphatases (AKP) with >94% of their biological activities retained in NSD powders and endow nanoparticle-based AKP-cyclodextrin-leucine (ACL) powders with improved aerosolization behavior. This can be evidenced by the fine particle (<4.46 µm) fraction (FPF<4.46) and FPF<1.66 (in unit percentage), of only 49.9% and 18.7% for the leucine-free ACL0, while significantly increased to 82.1% and 33.1% for ACL15, and further increased to >88% and >41% for ACL30/ACL45. The USP Chapters of traditional <601> and newly published <1604> were employed to determine derived metrics for aerodynamic particle size distribution (APSD). It was demonstrated that the authenticity of fitted values calculated in Chapter <601> was severely influenced by APSD profiles, and the fitted values can have immense differences from the actual values determined in Chapter <1604> . The differences can be minimized when the APSD is unimodal and normal across sized impactor stages. Hence, the authenticity of the fitted values can be improved. These new data deepen the understanding of APSD analyses and generate insights into the improvement of value authenticity for derived metrics, henceforward facilitating continuous improvements in quality control of inhaled products.

Transdermal and topical delivery systems (TDS) have emerged as the third-largest route of administration due to their ability to bypass first-pass metabolism and maintain stable plasma concentrations. Skin physiologically based pharmacokinetic (PBPK) models mechanistically characterize the percutaneous absorption process, predict local and systemic exposure, and enhance research and development efficiency through virtual clinical trials. This paper first elaborates on the theoretical foundation of skin PBPK modeling based on Fick's second law of diffusion and compares the model assumptions and application scenarios of four well-established and validated modeling platforms: Simcyp, GastroPlus, Skin-CAD, and PK-Sim. The findings indicate that Simcyp provides a refined depiction of skin physiological structure and is widely applied in clinical evaluation and special population prediction. GastroPlus focuses more on the mechanistic description of TDS formulations. Skin-CAD, as a specialized software, is extensively utilized for in vitro-in vivo extrapolation (IVIVE) predictions and formulation optimization. PK-Sim, as a freely accessible open-source software, has been used to investigate the physiological ontogeny of skin in pediatric populations. However, existing studies share limitations such as highly inconsistent model structures with varying complexity, challenges in acquiring accurate parameters, and a scarcity of physiological information for special populations. Future research should prioritize optimizing parameter acquisition methods and broadening physiological databases for pediatric, geriatric, and skin-lesion populations. Additionally, integrating non-invasive imaging technologies to construct high-precision 'digital twin' skin models represents a critical future direction. These advancements will drive the transition of PBPK models from descriptive tools to supportive instruments for individualized dosing and regulatory decision-making.

Glaucoma filtration surgery (GFS) is the definitive treatment for reducing intraocular pressure in patients with refractory glaucoma. However, postoperative scarring of the filtration tract is a major cause of surgical failure. Although artesunate (ART) exhibits significant antifibrotic efficacy, its clinical application is severely limited by poor solubility and a short half-life. This study designed and developed a new injectable hydrogel cross-linked by collagen and four-armed polyethylene glycol N-hydroxysuccinimide encapsulating ART (C-P@ART) to overcome the limitations of ART in ocular antifibrotic therapy and extensively examined its underlying mechanisms. Stable three-dimensional network structure, excellent biocompatibility, and sustained drug release characteristics of C-P@ART were validated through FTIR, rheological analysis, endotoxin-testing, scanning electron microscope (SEM), and in vitro and in vivo release assays. In a TGF-β1-induced fibroblast fibrosis model, C-P@ART significantly inhibited α-SMA expression concentration-dependently and exerted antifibrotic effects through dual regulation of TGF-β1/SMAD and PI3K/Akt pathways. Subsequently, we evaluated its antifibrotic efficacy in the rabbit GFS model, where the C-P@ART treatment group exhibited a significant reduction in postoperative collagen deposition and α-SMA-positive expression compared to the control group. C-P@ART inhibited NF-κB pathway activation and reduced inflammatory cell infiltration. In conclusion, these findings demonstrated that C-P@ART synergistically mitigates fibrosis and inflammation through sustained ART release, providing an innovative therapeutic strategy to enhance GFS outcomes.

Diabetes mellitus, chronic metabolic disease marked by persistent hyperglycemia resulting from inadequate insulin production or impaired action. Despite advancements in glucose-responsive insulin delivery systems, challenges persist such as limited responsiveness to dynamic glucose fluctuations, in vivo biocompatibility, and production scalability with uniform performance. However, insulin-loaded microspheres combined with microfluidics-based technology improve the subcutaneous insulin reservoir and homogeneous microsphere production rate. This study presents a microfluidic-engineered glucose-responsive controlled-insulin release microsphere using Glucose oxidase (GOx) as the glucose-sensing unit and a hybrid carrier composed of poly (lactic-co-glycolic acid) (PLGA) and acid-sensitive acetalated dextran (Ac-dex). The microfluidic-based fabrication method ensured uniform and controllable microsphere size and stable performance with satisfactory batch-to-batch reproducibility. In Streptozotocin (STZ)-induced diabetic mice, the microspheres maintained normal blood glucose levels for at least 20 hours. Absence of additional treatment-induced organ toxicity, systemic inflammation, and low hypoglycemic index ensured that the formulation is safe. Besides, this study provides a promising strategy for closed-loop insulin therapy, with potential clinical applications in improving glycemic control and reducing the burden of diabetes management.

Despite considerable advances in cancer therapy, the intrinsic heterogeneity of malignant cells continues to compromise therapeutic efficacy with conventional monotherapies, driving the need for combination treatments to achieve more durable and complete responses. The limited efficacy of conventional chemotherapy is largely attributable to the immunosuppressive tumor microenvironment, which is frequently perpetuated by epigenetic mechanisms, including aberrant DNA methylation. To overcome these limitations, we hypothesized that Decitabine (Dac)-mediated sensitization could dramatically enhance Sorafenib (Sor)-induced ferroptosis, and to test this synergy, we developed an innovative biomimetic codelivery platform comprising polymer micelles loaded with Sor surface-coated with exosomes encapsulating Dac (Exo&PM/D + S). This platform facilitates codelivery, enabling Dac-mediated DNA hypomethylation to remodel the tumor microenvironment and promote Sor-triggered ferroptosis. In vitro, Exo&PM/D + S exhibited potent anti-tumor activity by concurrently enhancing DNA demethylation and ROS accumulation. In mouse neuroblastoma models, the system significantly suppressed tumor growth, stimulated antitumor immunity, and extended survival. Mechanistic studies confirmed that Dac potentiates Sor-induced ferroptosis through epigenetic modulation. Thus, Exo&PM/D + S represents a promising nanotherapeutic strategy that synergizes epigenetic modulation with ferroptosis induction for enhanced anti-tumor efficacy.

Infected wounds represent a significant clinical burden owing to persistent infection, excessive inflammation, and impaired tissue regeneration. To overcome these limitations, we developed a sprayable N-succinyl chitosan/Pluronic F127 (NSC/PF127) hydrogel incorporating MoO2 nanoparticles, ciprofloxacin, and fibroblast growth factor-2 (FGF-2). At body temperature, the hydrogel rapidly transitions from a solution to a gel and responds to both pH changes and near-infrared (NIR) irradiation. MoO2 exhibits NIR-mediated photothermal activity, while CIP and FGF-2 are released in a sustained and pH-dependent manner, thereby maintaining antibacterial efficacy and growth factor bioactivity. In vitro studies demonstrated excellent cytocompatibility and significantly enhanced fibroblast and keratinocyte migration. The combined photothermal effect and antibiotic therapy effectively suppressed bacterial growth and disrupted established biofilms. In a rat model of Staphylococcus aureus-infected full-thickness wounds, the hydrogel composite significantly accelerated healing, reduced inflammation, promoted collagen deposition and angiogenesis, and enhanced tissue regeneration. Biochemical and gene expression analyses further indicated reduced oxidative stress and improved tissue regeneration. This multifunctional, sprayable hydrogel combines targeted antibacterial action with sustained pro-regenerative signaling, offering a promising strategy for further preclinical investigations of infected wound management.

The subcutaneous (SC) injection route is a commonly used and important method for therapeutic delivery of a wide range of compounds, and needle characteristics have a significant influence on patient pain, anxiety, safety, and other outcomes. This systematic review evaluates the evidence on how needle-specific characteristics (e.g. gauge, length, tip design, wall thickness, concealment) and administration- or device-related factors can affect patient-reported outcomes and clinical safety indicators during and following SC injections. A comprehensive search was conducted in MEDLINE, PubMed, Embase, and ClinicalTrials.gov in June 2024. Studies were included if they assessed the relationship between needle characteristics and pain, anxiety, safety, or related outcomes in individuals receiving SC injections. A dual-reviewer process was used for study selection, data extraction, and quality assessment. Sixty-two studies met inclusion criteria. Evidence consistently indicated that thinner and shorter needles reduced patient-reported pain and adverse events such as bruising and bleeding. Tapered and lubricated needles, hidden or retractable needle designs, and use of autoinjectors or prefilled syringes also contributed to reduced anxiety and improved user satisfaction. However, results were heterogeneous, and many studies lacked sufficient power or single-variable evaluation of individual needle parameters, limiting definitive conclusions. Needle characteristics significantly influence patient experience and safety with SC delivery. While both clinical evidence and practical experience clearly favor thinner, shorter, and concealed needles, further standardized, high-quality research is needed to isolate and quantify the specific contributions of individual needle characteristics to optimize injection practices and support patient-centered device design.

Currently, the commercial fixed-combination of two agents is facing several clinical challenges, including suboptimal intraocular pressure (IOP) reduction, which requires multiple daily administrations, compromised bioavailability due to rapid tear film clearance and nasolacrimal drainage, and preservative-induced ocular surface toxicity. To address these limitations, we intend to develop a novel preservative-free, long-acting fixed-combination formulation of carteolol hydrochloride and netarsudil dimesylate. This once-daily formulation demonstrates enhanced therapeutic potential through optimized physicochemical stability and extended ocular residence time in theory. However, commercialized netarsudil dimesylate is precipitated when the pH of the solution is above 5.4 or when carteolol hydrochloride is mixed with netarsudil dimesylate. Consequently, the preservative-free and long-acting fixed-combination carteolol-netarsudil containing hydroxypropyl methylcellulose (HPMC) as a thickener (FC-CN-TKN) was prepared in a pH about 5.0 solution using an extremely simple one-pot pH-adjusting solubilization strategy, achieving stable co-solubilization of both active pharmaceutical ingredients. The optimized FC-CN-TKN formulation demonstrated excellent physicochemical stability under refrigerated storage conditions. Additionally, FC-CN exerted no influence on the intraocular penetration of each active compound in the pharmacokinetic study, and HPMC-mediated viscosity enhancement significantly prolonged precorneal retention, further improving its residence time and bioavailability. Importantly, once daily, FC-CN-TKN exerted a potent IOP-lowering effect and protective effect on retinal ganglion cells. The innovative FC-CN-TKN was stable, safe, and effective, being a promising glaucoma therapy.

Messenger RNA (mRNA) therapeutics have revolutionized biomedicine by enabling direct in vivo programming of immune cells. This strategy bypasses the complex manufacturing and high costs associated with ex vivo cell therapies. However, efficient and specific systemic delivery of mRNA to target immune cell subsets remains a major translational hurdle. This review systematically examines engineering strategies that address this challenge. We first outline the key biological barriers to mRNA delivery, such as serum instability, nonspecific biodistribution, cellular uptake heterogeneity, and inefficient endosomal escape. Next, we comprehensively review advances in lipid nanoparticle (LNP) engineering, including discovering novel lipids, modulating compositions, conjugating targeting ligands, and incorporating stimuli-responsive elements, to enable enhanced tropism toward specific immune cells. Representative applications in oncology, protein replacement, autoimmune disease, and tissue regeneration are highlighted. Finally, we address translational challenges in safety, scalable manufacturing, and regulatory issues. The integration of rational material design, high-throughput screening, artificial intelligence, and interdisciplinary collaboration will be essential to advance next-generation targeted in vivo mRNA cell therapies toward clinical translation.

Extracellular vesicles (EVs) have emerged as promising tools for early cancer detection, therapeutic monitoring, and drug delivery in oncology. Artificial intelligence (AI), particularly machine learning and deep learning, offers new analytical tools and computational approaches for EV research. This review summarizes recent advances in the application of AI to EV isolation, characterization, diagnosis, and drug delivery, with particular emphasis on its potential to enhance tumor detection sensitivity, diagnostic accuracy, and the rational design of delivery platforms. Special attention is given to the roles and recent applications of AI models in integrating multimodal features, characterizing EV heterogeneity, supporting diagnostic classification, and modeling in vivo behavior. Moreover, we examine the integration of AI with EV-based microfluidic isolation, surface-enhanced Raman spectroscopy (SERS), fluorescence imaging, and multiomics analysis. Among these areas, AI-assisted EV diagnostic applications are comparatively closer to clinical translation, with several studies incorporating patient-derived samples and AI-assisted diagnostic platforms, whereas AI-guided therapeutic EV design strategies remain largely exploratory. With the continued accumulation of multicenter, cross-platform EV datasets, improvements in algorithmic robustness, and closer integration of computational and experimental workflows, AI may support further clinical evaluation of EV-based diagnostics and the systematic optimization of therapeutic EV platforms.