ABSTRACT: Large-scale cultivation of Bacillus thuringiensis Berliner (Bt) crops has led to the rapid development of drug resistance. Herein, a fluorescent star poly(amino acid) is synthesized with L-isoleucine functionalization for the efficient delivery of either positively or negatively charged exogenous proteins into live cells. Poly(amino acid)s (P1)/Cry1Ab complexes greatly increase the cytotoxicity of the Bt toxin, Cry1Ab, and efficiently kill Bt-resistant pests.