Harnessing facial neuronal pathways via iontophoresis for targeted intradermal delivery of bimodal spherical nucleic acids to the brain for anti-glioma  effect

Background: Glioblastoma (GBM) remains one of the most aggressive brain tumors due to barriers in drug delivery across the blood-brain barrier (BBB) and its profoundly immunosuppressive tumor microenvironment (TME). These limitations restrict therapeutic penetration into tumor sites. While intranasal strategies exploit trigeminal/olfactory routes, mucociliary clearance and off-target exposure have limited clinical translation. Here, we developed a facial dermal iontophoresis-based system to deliver immune-modulating nanoparticles through the facial neuro-lymphatic network to bypass the BBB and reprogram the TME. Methods: To overcome delivery barriers affecting immunotherapies intended to modulate tumor-associated and peripheral immunity, we integrated two approaches. First, we established iontophoresis as a minimally invasive method to bypass the BBB and enhance the transport of therapeutics delivered via facial intradermal (i.d.) injection. Second, we engineered a bimodal Spherical Nucleic Acid (bi-SNA) platform that activates cGAS and inhibits STAT3. Bi-SNAs consist of a 15-nm gold core functionalized with a hairpin oligonucleotide with STAT3-decoy sequences, enabling simultaneous cGAS activation and STAT3 sequestration. Bi-SNAs elicit potent antitumor immunity in multiple HGG models and outperform cGAS-agonist monotherapies. A dedicated iontophoresis device was designed for preclinical assessment using murine GBM models, and iontophoretic parameters (current density, waveform, electrode placement) were optimized for controlled transdermal SNA transport. Biodistribution was measured by 3D fluorescence CT-IVIS with ICG-labeled SNAs, gold levels by ICP-MS, and immune modulation by multispectral flow cytometry. Results: I.d. Bi-SNA delivery with iontophoresis significantly suppressed tumor progression, depleted immunosuppressive myeloid cells, and increased recruitment/activation of effector T cells. IVIS imaging showed a two-fold increase and faster kinetics of SNA trafficking from facial planes to the brain without detectable systemic spread, with preferential accumulation along maxillary-olfactory and temporomandibular conduits. ICP-MS revealed ~20-fold higher gold deposition in the brain and trigeminal nerve within 12 hours compared with passive i.d. delivery. Conclusions: Iontophoresis-enhanced i.d. delivery provides a powerful non-invasive strategy for brain-targeted immunotherapy, leveraging neuronal pathways to bypass the BBB and reprogram the GBM TME. This establishes a foundation for patient-adaptable, at-home nanotherapeutic delivery for brain tumors.