Optically Controlled Nanosensors For Highly Sensitive Imaging Of Cancer Cells

Diagnosis and treatment of cancer is a global concern,and how to make accurate early diagnosis of cancer has great significance in improving the survival rate of cancer patients.Traditional methods of cancer detection can't play a role at the microscopic level.Therefore,quantum dot-based molecular imaging technology has been rapidly developed and has played an increasingly important role in many fields.MicroRNAs(miRNAs)are a class of small noncodingRNA molecules that act as crucial post-transcriptional regulators of gene expression.MiRNAs play major roles in different developmental processes including metabolism,cell proliferation,apoptosis,and developmental timing.Aberrant levels of miRNA are found to be implicated in a variety of human diseases such as cancer,cardiovascular disease,inflammatory disease,and Alzheimer's disease.It has been revealed that miRNA levels are highly dynamic at different developmental stages or in response to therapy.Sensitive imaging of miRNA in living cells is of great value for disease diagnostics and prognostics.While signal amplification-based strategies have been developed for imaging low-abundance disease-relevant miRNA molecules,precise temporal control over sensor activity in living cells still remains a challenge,and limits their applications for sensing miRNA concentration dynamics.Herein,we report a class of photocaged nanoparticle sensors for highly sensitive imaging of miRNA in living cells with temporal control.The sensor features a DNAtemplated gold nanoparticle-quantum dot satellite nanostructure which is temporarily inactivated by a photocaged DNA mask.Upon UV light irradiation,the sensor restores its activity for catalytic sensing of miRNA in living cells via entropy-driven two-step toeholdmediated strand displacement reactions.We show that the sensor exhibits quick response to UV light,robust intracellular stability,and high specificity and sensitivity for the miRNA target.On the basis of this strategy,precise control over sensor activity is achieved using an external light trigger,where on-demand sensing could be potentially performed with spatiotemporal control.