Development of biocompatible nanogel for sustained drug release by overcoming the blood brain barrier in zebrafish model

•Delivery of drug to the zebrafish brain was achieved by overcoming the blood–brain barrier.•PNIPAM nanogel had prepared and functionalized with polysorbate 80 for sustained donepezil delivery.•Acetylcholineesterase inhibition in zebrafish brain had confirmed the drug release by donepezil conjugated nanogel.•Concentration dependent swim behavior and neuronal biocompatibility is reported in adult zebrafish.•Therapeutic efficiency of the donepezil conjugated nanogel was studied through cardiac and phenotypic assessment in zebrafish embryos.