“Allergolds”: Gold Nanocluster-Based Bioconjugates of Food Allergens with Reduced Immunoglobulin E Binding

Allergen-specific immunotherapy represents the only method of achieving a lasting reduction in the severity of allergic symptoms. However, the need to expose patients to the allergens to which they are sensitized carries risks. One solution is to use denatured allergens whereby the structure of allergenic proteins is disrupted, preventing their recognition by immunoglobulin E (IgE) antibodies and thus reducing the risk of adverse reactions. Denaturation is often carried out by using chemical cross-linking to generate allergoids. Gold nanoclusters (AuNCs) are emerging as versatile tools in biotechnology due in part to their ability to conjugate a wide range of biological molecules. Previous works have described the formation of AuNC using egg allergens such as Gal d 4 (lysozyme), Gal d 2 (ovalbumin), and whole egg whites. In all cases, AuNC bioconjugation disrupted the protein structure, allowing for their use in biosensing applications. In this work, we hypothesize that these AuNC-allergen bioconjugates could be used to generate "Allergolds", chemically altered versions of allergenic proteins analogous to traditional allergoid formulations. Using spectroscopic techniques, we confirm that the formation of AuNC bioconjugates of the chicken egg Gal d 4 and Gal d 2 disrupts protein structure when generated from both purified protein and whole egg whites. This structural perturbation was found to be resilient to a range of chemical conditions and successfully disrupted recognition by human IgE. These results establish Allergolds as a potential tool for generating systematically denatured allergens from both purified proteins and biological extracts.