Antibacterial carbon dots derived from polyethylene glycol/polyethyleneimine with potent anti-friction performance as water-based lubrication additives

Carbon dots (CDs) are obtained from polyethylene glycol and polyethyleneimine by a simple hydrothermal method at 200 degrees C. The water dispersion of CDs (0.2 wt%) remains transparent even after standing for a month. Next, the tribological properties of CDs as water lubricating additives are evaluated by multifunctional micro-friction tester. Specifically, after adding 0.2 wt% of CDs, the mean friction coefficient and wear volume of water-based lubrication are reduced by 59.77 and 57.97%, respectively. Meanwhile, the antibacterial properties of CDs are evaluated by minimum inhibitory concentrations test, long-lasting antibacterial stability, and biological scanning electron microscopy experiment. The minimum inhibitory concentrations of CDs against Escherichia coli and Staphylococcus aureus are 62.5 and 15.56 mu g ml(-1), respectively. And the result show that, after co-cultivation with CDs, the integrity of the bacteria is seriously destroyed, which accelerates the leakage of the cell contents and eventually leads to the death of bacteria. More importantly, the antibacterial performance can be maintained stably at least for 1 month even if the continuously adding of bacterial suspensions. Therefore, as an advanced lubricating additive with antibacterial and anti-friction functions, the prepared CDs have a bright future in the field of water lubrication.

Automated summary

Carbon dots (CDs) obtained through hydrothermal method exhibit excellent anti-friction and antibacterial properties as lubricating additives in water-based lubrication. After the addition of CDs, there is a significant reduction in friction coefficient and wear volume in water lubrication.