Preparation, gradient extraction and surface polarity-dependent antibacterial properties of cockscomb seeds-derived carbon dots

Abstract

Cockscomb seeds-derived carbon dots (CSCDs) were fabricated by hydrothermal method with common cockscomb seeds. The prepared CSCDs exhibit selectively antibacterial properties towards Gram-positive bacterias, such as Staphylococcus aureus (S. aureus) and Staphylococcus epidermidis (S. epidermidis). Then, the CSCDs were separated to three groups with lipophilic, amphipathic and hydrophilic ones by simple gradient extraction. Interestingly, the three groups of CSCDs exhibited different antibacterial activities, and the amphipathic CSCDs(ACSCDs) showed best bacterial inhibition. This phenomenon might stem from the surface properties of the amphipathic CSCDs, which have both hydrophilic region and hydrophilic region on the surface. The structure might help the samples to penetrate the bacterial membrane more easily, and finally cause apoptosis. This work not only supplied a novel antibacterial carbon dots, but also further revealed that surface chemistry might be an important factor which could affect the bactericidal performance of carbon dots.