The Efficacy Of The Multifunctional Nucleic Acid Nano Drug-loading System For Tumors

The diagnosis and treatment of cancer are of great concern in the field of biochemical analysis,which of the methods involved are more and more rich and innovative.Among them,the functional nucleic acid nanometer system is promising in research and application prospect.In this paper,a multifunctional DNA nanosphere system was designed.On the one hand,a multifunctional DNA nanosphere system was formed by the method of DNA self-assembly and the method of rolling circle amplification(RCA).As a vector of DOX for the specific recognition and targeting of different cancer cells,it can also be used for the determination of glutathione content of small molecules in cells.The results of experiment showed that the DNA nanospheres had a good biocompatibility and strong selectivity and reduced the damage of normal cells so that achieved the killing effect on cancer cells.It also had a high sensitivity and good reproducibility to the detection of glutathione.On the other hand,on the base of RCA,using the proximity ligation(PLA),this paper combined oxidized graphene and mesoporous silica.Inorganic nano-materials achieved the detection of small molecules in cell and intracellular drug release simultaneously.The design effectively reduces the biological in addition to the detection samples outside the irrelevant effects of the digestion,so that the detection is more feasible and highly sensitive.The main contents are as follows:1.DNA-spheres decorated magnetic nano-composite based on terminal transfer reaction for versatile target detection and cellular targeted drug delivery: First,DNA-spheres were formatted by DNA self-assembly technique.Secondly,on the basis of the synthesis of DNA-spheres,the DNA primer strand containing the disulfide bond can be hybridized with the DNA single strand to form the DNA-spheres containing the disulfide bonds.The DNA-spheres can achieve the detection of intracellular glutathione content with a high sensitivity of detection.Furthermore,the template chain involved in the RCA process was modified by the sgc8 aptamer,which specifically recognizes the PTK7 protein overexpressed on CEM cells.Finally,based on the formation of DNA-spheres,we also integrate multiple adenine(A)bases at the end of linear long chainfrom RCA by the action of terminal transferases,which may be linked to poly-(T)-single strand modified by folic acid,resulting in the formation of DNA-spheres containing folic acid.So the spheres can specifically recognize those cancer cells that will over express folate receptors on the surface,such as HeLa cells,etc.2.Proximity ligation mediated amplification to ATP response and open DNA-gate on mesoporous silica for drug delivery: proximity ligation(PLA)can be reacted with two different single-stranded DNA molecules so that the two DNA single-stranded tails can be closely in the space which at the role of DNA ligase,the connection reaction of the free 5'and 3' end was occurred.Therefore,we designed a DNA primer strand containing ATP aptamer as a linker chain,a template chain that could complement with the DNA primer strand,and a signal strand that hybridized to the complementary of the template chain.These DNA single strands can be both adsorbed on graphene oxide(GO),which has a good biocompatibility and nanoscale particle size.In cells,once the system meets with ATP molecules,ATP aptamer can be involved with ATP molecules,resulting in proximity ligation.In the role of DNA ligase,it can produce a circular DNA complex and then the RCA process was completed.The long linear DNA single chain contains thousands of bases that can be combined with a large number signal chain attached to GO,releasing strong fluorescence.The detection of fluorescence can achieve the measurement of ATP concentration in a high sensitivity.At the same time,in order to improve the selectivity of this system,we modified the folic acid molecules on the surface of GO,which could specifically bind to cancer cells overexpressing folate receptors,such as HeLa cells,not the MCF-7 cells.The study results further illustrate that potential application of the system in cancer diagnosis.On the other hand,through the electrostatic attraction adsorption,the DNA single strand could be attached to the mesoporous silica,as the gate DNA single chain,blocking the micro-channel crossing and encapsulation of internal pre-equipped DOX.The system was based on the closed drug delivery and controlled release structure.Once the ATP molecule is present,the linker DNA will be released from the GO surface,hybridizing to the template DNA of the GO surface,and joining with ligation enzyme.RCA reaction is followed by the addition of the phi29 DNA polymerase.The product of RCA reaction contains a base fragment complementary to the signal DNA,allowing the fluorescent oligonucleotide probe to be released from the GO surface out and fluorescence is recovery.The strong fluorescence signal realized the sensitive detection of ATP.Gate DNA were modified to the surface of the MSN by electrostatic attraction to encapsulate DOX.After the above-mentioned RCA process,its resulting long DNA chain containing a base fragment complementary to gate DNA,will be hybridized to the gate DNA strand on the surface of MSN,which opened the MSN hole and released the drug DOX into cell for HeLa cell therapy.And the specificity to folate receptor-overexpressed cell was satisfactory which would be beneficial for cancer therapy.The system effectively reduces the digestion of other substances outside the target molecule and reduces the side effects of anticancer drugs,making the detection method more highly sensitive,selective and feasible.