Viscosity-activated carbon dots for noninvasive disease diagnosis, therapeutic efficacy assessment and anticancer drug screening

Abnormal levels of intracellular microviscosity have a close relationship with some diseases and pathologies. Therefore, quantitative imaging of viscosity at the cellular and organ levels is beneficial for disease diagnosis, curative effect evaluation, and anticancer drug screening. Herein, we synthesized viscosity-activated orange-red emitting carbon dots (named as LP-CDs) from lignin and p-phenylenediamine using a one-step method, whose fluorescence intensity, lifetime, and quantum yield significantly increase with rising viscosity. Meanwhile, the fluorescence intensity of LP-CDs also has a good linear relationship with the solution viscosity. Taking the advantages of high sensitivity, noninvasiveness, and rapid result output of fluorescence imaging, LP-CDs can visualize the cellular viscosity changes induced by inflammation and hyperglycemia, and image tumor evolution. More importantly, LP-CDs can be used as powerful sensors to screen anticancer drugs in vivo by evaluating therapeutic effects. This work provides a new scheme for constructing robust nanoprobes to achieve the diagnosis and imaging-guided surgery of viscosity related diseases.