Proximity ligation detection of lectin Concanavalin A and fluorescence imaging cancer cells using carbohydrate functionalized DNA-silver nanocluster probes.

A novel method for study the interaction between carbohydrate and lectin was developed in homogenous solution. DNA was introduced to the recognition process of carbohydrate with protein. Due to the versatile detection mode of DNA, the detection efficiency for carbohydrate and protein was highly promoted. Herein, two kinds of mannose-DNA conjugates were synthesized. One of which was used to prepare DNA-templated silver nanocluster (AgNCs) and the other one contained guanine-rich DNA sequences. When the mannose of two conjugates binding to lectin Concanavalin A (Con A), great enhancement on fluorescence intensity was obtained due to the proximity ligation of the DNA-templated Ag NCs with guanine-rich DNA sequences. Hence Con A can be quantified conveniently in homogenous solution using Ag NCs with low toxicity and tunable fluorescence. Moreover, carbohydrate functionalized DNA-templated AgNCs was also utilized for cancer cell imaging based on the recognition of mannose with mannose receptor on cancer cell MDA-MB-231.