Research On DNA-Templated And Near-Infrared Quantum Dots For Bioimaging

Quantum dots(QDs) are semiconductor nanocrystals with unique size dependent optical and electronic properties. Since QDs were introduced into the biomedical field in 1998, this intriguing nanomaterials has attracted numerous attentions and the related research field has developed extremely fast over the past ten years. For bio-applications, small thiol-cotaining molecules are mostly used as the ligands for QDs synthesis in aqueous which have been developed recently. Aqueous solution-based synthesis has attracted more attentions due to its mild synthetic conditions, the elimination of the solubilization step, and the use of simple and cheap reaction instruments. Recent research in this field has been focusing on developing less toxic QDs, constructing compact and biocomposites QDs with novel capping ligands, novel imaging and sensing techniques based on QDs, and multifunctional QD nanocomposites.Recently, the QDs synthesis was used to directly generate biofunctionalized QDs in one step using chimeric DNA as templates. The chimeric DNA contains a phosphorothioate domain that serves as the passivation domain for QD growth and a phosphate domain that serves as a biorecognition domain for biomolecular binding. The as-prepared QDs not only exhibit excellent size-dependent optical properties, but also using DNA valencies to assemble a high-order nanostructure which can exhibit various geometries. Additionally, DNA has been proven to be highly versatile for biomolecular targeting. Various types of biomolecules, including nucleic acids, proteins, cell-surface receptors, and small molecules, can be targeted by DNA aptamers with high affinity and specificity.NIR QDs have been extensively used for living animal optical imaging such as tumor imaging, blood vessel imaging, and lymph node mapping. The first generation of NIR QDs are composed of the heavy metal such as cadmium, mercury, or lead. The as-prepared QDs possess more toxic in bio-application. The second generation of QDs such as indium-based and silver-based QDs are believed to be less toxic and are currently more popular in animal imaging studies. However, one disadvantage of these QDs is the relatively low quantum yield, which may need to be further improved in the future. The last type of the NIR QDs is the core-shell QDs which exhibit low toxic and high QY. They have been widely used for in vivo imaging after conjugating biomolecular targets on their surface.Herein, in this repot we first synthesized the water-soluble QDs in aqueous, then the QDs were functionalized with high specific and efficient bimolecular for imaging. There are two parts in this article. On the one hand, we designed a DNA-templated QDs for dual-targeting imaging in live cancer cells. On the other hand, we functionalized as-prepared NIR QDs and applied them to animal imaging.