Advancements in Nanomedicine for Allergic Diseases: Diagnosis, Toxicity, and Therapeutic Strategies

Allergic diseases affect over one billion people worldwide as a common chronic condition. Conventional treatments often relieve symptoms but lack long-term efficacy or safety. Over the past decade, nanomedicine, i.e., nanoscale drugs and delivery systems, has emerged as a promising alternative that leverages the tunable physicochemical properties of nanoparticles (NPs) and enhances both diagnosis and treatment of hypersensitivity disorders. In diagnostics, nanoparticle-based biosensors have achieved detection limits as low as 42 fg/mL with specificity exceeding 90% for food and aeroallergen proteins. Therapeutic applications comprise various NPs, including gold, silver, iron oxide, carbon-based, lipid-mediated, polymeric, dendrimeric, and virus-like, as delivery vehicles and as immunomodulators. Preclinical models detect >50% reductions in pro-inflammatory cytokines (IL-4, IL-5) and two- to 3-fold reductions in eosinophil infiltration following NP-augmented allergen immunotherapy, with antigen-specific IgE titers reduced by up to 70%. Although such advancement has occurred, nanotoxicology studies highlight dose-dependent organ concentration and prolonged pulmonary half-lives that necessitate rigorous biosafety evaluation. Regulatory and manufacturability concerns remain significant hurdles for clinical translation. This article reviews up-to-date quantitative performance metrics for nanoparticle therapeutics and diagnostics in allergy control, critically examines the toxicity profiles and translational issues, and brings out directions toward individualized, safe nanotheranostic platforms.