You should better specify what you mean by "washing". I work with carbon nanodots, and the information I can provide you with is the following: the solubility of my dots in DCM is extremely low (as opposed to polar solvents), which is quite common for carbon dots, indeed. I can prepare stable solutions in DCM up to about 10-4/10-5 g/L. Hope it helps. Please answer if you have further questions.