| Cell is the element of life activity and structure in living system. Pathologicalmechanism of all diseases often started with cell research. As the control center of cell,cell nucleus is the final target position of the most drugs. So, investigating cancer cellnucleus with drugs treatment is crucial for the design of new anticancer drugs, thedevelopment of novel diagnostic strategies, and the advancement of cancer therapyefficiency. Currently, the methods of cell nucleus research mainly include traditionalcell biology methods (immunecytochemical, Western Blot and gel electrophoresis etc.)and spectral analysis methods (nuclear magnetic resonance, fluorescence spectroscopy,and single molecule force spectroscopy etc.). While, how to in situ explore molecularchanges of cell nucleus under external stimulation in noninvasive means is stillchallenging.Raman spectroscopy as an analysis means can provide spectral fingerprintinformation of materials at molecular level. Furthermore, its advantageouscharacteristics are noninvasive and label-free. However, the spectral information ofbiological samples is complicated, and also the inherent low sensitivity of Ramanspectroscopy limited its applications in biomedical areas. In the1970s, the detectionsensitivity of Raman spectroscopy is greatly improved by Surface-enhanced RamanScattering (SERS). Even can be realized single molecule detection in the90s. Moreover, SERS spectroscopy possesses advantages of narrow spectral bands, richmolecular information, which makes it feasible for studying the cell biology relatedareas.How to effectively obtain in situ SERS spectra of cell nucleus is the key point ofthis study. Based on this point, AuNR nuclear probe was prepared. Furthermore, asthe SERS substrate, the cell nuclear probe was used to in situ explore molecularchanges of cancer cell nucleus with the anticancer drug models (Doxorubicin andHoechst33342) treatment. The concrete contents of this research are as follows:The cell nuclear probe was prepared by surface modification of AuNRs. First,gold nanorods (AuNRs) with proper size and the excitation wavelength-matchedlocalized surface plasmon resonance (LSPR) property are prepared by seed-mediatedgrowth method and chemical etching method. Then, to improve the biocompatibilityand nuclear specificity, thiol-modified polyethylene glycol polymers (PEG) andnuclear localizing signal peptides (NLS) were assembled around AuNRs by Au-Scovalent interaction. By dark-field imaging, it can be found that most of theNLS-PEG-AuNRs concentrated in the cell nuclei, only a small amount of AuNRsexisted in cytoplasm. With AuNRs enhancement, we obtained the SERS spectra ofcell nucleus. Besides, the viability of SGC-7901cell after incubation with nanoprobeswas tested, the results indicating that our nuclear targeting nanoprobes were lowcytotoxicity. So, AuNR probe with nuclear specificity, low cytotoxicity and highSERS effecting was successfully prepared. The nuclear targeting probe can be furtherapplied to study the action of anticancer drugs.Based on AuNR nuclear targeting probe, we investigated the stimulation ofcancer cell nucleus with drugs treatment by in situ SERS spectroscopy. We choseDNA binder (Hoechst33342) and anticancer drug (doxorubicin, Dox) as two drugmodels. Owing to the cell nucleus will present intensive fluorescence once cell nucleiare recognized by the two kinds of small molecules, dark-field and fluorescencecoimaging are used to locate the AuNR targeting probe and drugs. With the assistance of dark-field and fluorescence coimaging, in situ SERS spectra of cell nucleus beforeand after drugs treatment were obtained. Also, through assigning and analyzingcharacteristic Raman bands, we explored the molecular changes of cancer cell nucleuswith drugs treatment. |
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