Preparation Of Functional Nanoparticles For Biomolecule Detection And Cell Imaging

As a worldwide problem to be solved,cancer has attracted high attention from scientists at home and abroad for the invention of early detection methods and new anti-cancer drugs.Many studies have shown that miRNA is closely related to many kinds of cancer as a cancer indicator,so it can be used for the early diagnosis of cancer.However,its short length,easy degradation,and the lack of components in RNA make the miRNA detection faceing a great challenge.In addition,some commonly used detection methods(in-situ hybridization,blotting,the polymerase chain reaction,etc.)are time consuming and low sensitivity,limiting their development.Therefore,it is very important to find a simple and rapid detection method.Semiconductor nano-particles have great potential due to their superior fluorescence,light stability and narrow emission peaks.In addition to the early diagnosis of cancer,the invention of anticancer drugs is also an effective treatment.Based on the above background,the article mainly adopted CPNs-COOH-ssDNA as a fluorescence probe to classify and quantify microRNA;and then used the modified hollow gold nano-sphere HGNs as anti-cancer drug to inhibit the growth of cancer cells.For this purpose,the following work has been done:(1)The negatively charged CPNs-COOH were formed by co-precipitating polymer[(9,9-dioctylfluorene)-trans-co-(1,4-benzo-(2,1',3)-thiadiazole)](PFBT)and amphiphilic phospholipids-polyethylene glycol-carboxyl groups.The fluorescence and ultraviolet spectrum show that CPNs-COOH has a narrow excitation peak and emission peak,which is in favor of the single particle tracking and cell imaging experiments.In the stability test,we found that they are not susceptible to external circumstances(pH,storage time,salt concentration),showing their well stability.More importantly,their unique photostability was further verified by the microscopy experiment.(2)The CPNs-COOH was modified with NH2-ssDNA as a fluorescent probe.At the monolayer level,three sizes of fluorescent probes were used to investigate transient hybridization in different concentrations of PBS.Then the optimum probe was selected for microarray analysis of let-7a/let-7c and the quantitative detection of let-7a.The data analyzed from Matlab showes the 30 nm fluorescent probe is more appropriate.The quantitative analysis shows that the miRNA concentration is proportional to the number of transiently hybridized particles.(3)The hollow gold nanospheres(HGNs)with near-infrared characteristic were successfully synthesized using sacrificial cobalt as the template.TEM and DLS demonstrate the particle size of HGNs is about 30 nm.The UV spectroscopy shows that the emission wavelength is in the near-infrared range,which could be applied to the photothermal therapy.Next,HGNs is linked with Lycosin-I(an anti-cancer polypeptide)by Au-S interaction in order to inhibit the growth of cancer cells.