Nanostructured fluorescent particles derived from natural molecules were prepared by a green synthesis technique employing a microwave method. The precursors citric acid (CA) and cysteine (Cys) were used in the preparation of S- and N-doped Cys carbon dots (Cys CDs). Synthesis was completed in 3 min. The graphitic structure revealed by XRD analysis of Cys CDs dots had good water dispersity, with diameters in the range of 2–20 nm determined by TEM analysis. The isoelectric point of the S, N-doped CDs was pH value for 5.2. The prepared Cys CDs displayed excellent fluorescence intensity with a high quantum yield of 75.6 ± 2.1%. Strong antimicrobial capability of Cys CDs was observed with 12.5 mg/mL minimum bactericidal concentration (MBC) against gram-positive and gram-negative bacteria with the highest antimicrobial activity obtained against Staphylococcus aureus. Furthermore, Cys CDs provided total biofilm eradication and inhibition abilities against Pseudomonas aeruginosa at 25 mg/mL concentration. Cys CDs are promising antioxidant materials with 1.3 ± 0.1 μmol Trolox equivalent/g antioxidant capacity. Finally, Cys CDs were also shown to inhibit the acetylcholinesterase (AChE) enzyme, which is used in the treatment of Alzheimer’s disease, even at the low concentration of 100 μg/mL.

源自天然分子的纳米结构荧光颗粒是通过采用微波方法的绿色合成技术制备的。前体柠檬酸 (CA) 和半胱氨酸 (Cys) 用于制备 S 和 N 掺杂的 Cys 碳点 (Cys CDs)。合成在 3 分钟内完成。Cys CDs点的XRD分析揭示的石墨结构具有良好的水分散性，通过TEM分析确定直径在2-20nm范围内。S、N掺杂CD的等电点为pH值为5.2。制备的 Cys CD 显示出优异的荧光强度，量子产率高达 75.6 ± 2.1%。在 12.5 mg/mL 的最低杀菌浓度 (MBC) 下观察到 Cys CDs 对革兰氏阳性和革兰氏阴性菌具有很强的抗菌能力，对革兰氏阳性和革兰氏阴性细菌具有最高的抗菌活性金黄色葡萄球菌。此外，Cys CD在 25 mg/mL 浓度下提供了对铜绿假单胞菌的总生物膜根除和抑制能力。Cys CDs 是一种很有前途的抗氧化材料，抗氧化能力为 1.3 ± 0.1 μmol Trolox 当量/g。最后，Cys CD 也被证明可以抑制用于治疗阿尔茨海默病的乙酰胆碱酯酶 (AChE)，即使在 100 μg/mL 的低浓度下也是如此。