Biocompatibility and Toxicity Evaluation of an Elastin‐Based Nanogel Carrier for Enzalutamide: Comprehensive Characterization, Controlled Release and Assessment in Zebrafish Embryos

ABSTRACT Nanomedicine combines nanotechnology with healthcare, offering transformative possibilities in drug delivery and targeted therapies. The unique properties of nanomaterials—such as their high surface area owing to their microscopic size—make them especially valuable in treating various diseases. Nanogels—polymeric nanomaterials which are designed to be modular—can be enabled to carry both water‐soluble and fat‐soluble drugs. They enable controlled drug release, protect against metabolic degradation and ensure targeted delivery to cancer cells, thereby reducing undesired drug interaction and systemic toxicity. Elastin, known for its biocompatibility and natural degradability, could play a transformative role in the biomedical landscape. Its mechanical properties can be tailored to improve drug delivery systems with enhanced loading capacities with stimuli responsive release. Enzalutamide (EZA), a drug used in prostate cancer treatment, functions by blocking androgen receptor signalling, thereby inhibiting cancer progression. Yet, resistance to castration treatment triumphs over EZA. Hence constructing a carrier that can enhance EZA's availability within the tumour environment was hypothesized by using elastin protein. The elastin nanogel (ENG) was characterized to understand physical properties such as size, drug encapsulation and rate of drug release. Furthering the need to assess safety of ENG along with its drug encapsulated counterpart. Zebrafish ( Danio rerio)— a model organism in biomedical research due to its genetic similarities to humans—was utilized. Translucency of embryos makes it ideal for studying developmental morphology. Its high sensitivity to dissolved substances makes it a valuable model for toxicological studies, environmental monitoring, and drug discovery. This study evaluates the acute toxicity of EZA‐loaded ENG at various concentrations (2.5, 5, 7.5 and 10 μg/mL). Toxicological endpoints including viability, mortality, hatching rate, heart rate and morphological abnormalities were assessed at multiple developmental stages (0–96 hpf). At 96 hpf, pooled embryo samples from each group underwent total RNA extraction, cDNA synthesis and quantitative real time PCR targeting seven developmental genes ( Hoxa3a, mef2ca, Nkx2.5, pax6a and Runx2a ) related to organogenesis, notochord, cardiac, skeletal and spinal cord development, normalized to GAPDH expression. The EZA + ENG group demonstrated reduced toxicity relative to free‐form EZA across both phenotypic and molecular parameters, suggesting improved biocompatibility and potential for safer drug delivery. These findings support the utility of elastin‐based nano carriers in mitigating the developmental toxicity of antiandrogenic therapies.