Nano-Gold And Quantum Dots Composites For The Application In Imaging, Drug Delivery Of Cancer

The development of nanotechnology has had a great influence on different fields,especially materials science,biotechnology and pharmacotherapy.The application of nanomaterials in drug carriers has been studied well,but anticancer drugs-releasing of lowabundance nucleic acids in living cells remains challenging because of the relatively low responsiveness and Non-selectivity to cells of conventional drug carriers.In order to solve this problem,we designed a drug carriers based on DNA-templated DOX-loaded gold nanoparticle(GNP)-quantum dots(QD)assembly for catalytic drugreleasing of cancer-related microRNAs in living cells with signal amplification capacity.We show that a single microRNA molecule could catalyze the disassembly of multiple QDs and DOXs of GNP through a DNA-programmed thermodynamically driven entropy gain process,yielding significantly amplified QD photoluminescence and better therapeutic effect.Compared with the traditional drug carriers,we found that the catalytic system can respond to low levels of nucleic acids,quickly and accurately distinguish between normal cells and cancer cells,and kill cancer cells.This system is composed of ssDNA Linkered gold nanoparticle and CdTe QDs with site targeting of MicroRNA-21.Molecules of the cancer drug doxorubicin were intercalated into the stem region of DNA sequence.The presence of MicroRNA-21 or cognate DNA could catalyze the disassembly of nanocarrier,leading to inner chain substitution followed by the release of the QDs and trapped doxorubicin emiting the fluorescence of the two materials.This bionanocomposites could specifically distinguish tumor cells and normal cells based on MicroRNA-21 activity,and precisely release doxorubicin in response to MicroRNA-21 in tumor cells,and prevent toxicity to normal organs.