Green preparation of a novel cationic surfactant derived from starch carbon dots and the high surface activity as well as the antibiosis for E. coli and S. aureus

We report a green approach of preparing cationic surfactant with starch. • None of any organic solvent is used during the whole procedure. • The cationic surfactant differs entirely with conventional one in structure. Renewable carbohydrates provided abundant resources for the preparation of carbon dots (CDs), which could serve as a starting material for synthesis of fine chemicals. In this work, soluble starch was first formulated into an aqueous dispersion and then converted into starch-derived CDs (designated as SCDs) via hydrothermal treatment. Subsequently, SCDs were facilely and efficiently modified with n -dodecylamine in an aqueous medium (the modified product was denoted as SCDs-C12). Experimental results demonstrated that a dilute solution of SCDs-C12 reduced the surface tension of water from 72.0 to 31.9 mN·m −1 (25 °C), and its surface activity was comparable to that of some novel gemini surfactants. Additionally, the positively charged SCDs-C12 exhibited excellent performance in inhibiting the growth of E. coli , with a minimum inhibitory concentration of only 0.05 mg·mL −1 , outperforming many previously reported CD-based materials. In summary, this work developed an environmentally friendly and green strategy for the fabrication of multifunctional cationic surfactants. Download: Download high-res image (74KB) Download: Download full-size image