Abstract: The positively and negatively charged nanoparticles with pH responsiveness were prepared by biocompatible poly-γ-glutamic acid (γ-PGA) and chitosan (CS) , and were used to load the antibiotic amoxicillin. The structures and morphologies of the drug-loaded nanoparticles were characterized by Dynamic Light Scattering (DLS), Fourier Transform Infrared Spectroscopy (FT-IR), X-Ray Diffractometer (XRD) and Transmission Electron Microscopy (TEM). The pH responsive drug release of these nanoparticles to drug release and their toxicity to cells were investigated. The application of these two types of nanoparticles as drug carriers was also investigated from the aspects of anti-protein pollution and inhibition of Escherichia. coli and Staphylococcus aureus. Results showed that the sizes of surface charges can be easily tailored by adjusting the amount of γ-PGA and CS. Also, negatively charged nanoparticles displayed better performance of pH controlled drug release. Under simulated stomach environment, the sizes of the drug-loaded nanoparticles were between 200 nm and 300 nm and the cumulative release of amoxicillin was only 25%. However, in the simulated intestinal cell gap environment which was neutral or weakly alkaline, the mean particle size was increased to about 1 μm and the cumulative drug release was enhanced to 85%. In addition, the nanoparticles had a function of lowering the toxicity of drugs to normal cells by 20%, and they can improve the inhibitory effects on intestinal bacteria by about 42% compared to the free drug.