Design And Application Of Novel Fluorescent Probes For Intracellular Small Molecular Reactive Species

In recent years, the fluorescent dyes and silicon nanoparticles have beenincreasingly valuable materials of considerable interest in bioanalytical chemistry. Asa new type of probe with special small dimension effects combined withbiocompatibility, easy-modification and low toxicity of silicon particles, it exhibitsmany different optical characteristics compared with the traditional single-wavelengthfluorescent probes, and thus has attracted great attention in the research field onbioanalytical chemistry.Fluorescent probes have become increasingly widely employed potent tools forreal-time, noninvasive, sensitive and selective imaging dynamics changes inbioanalytes. Various fluorescent probes for imaging intracellular small molecularreactive species (ISMRS) have been developed based on fluorescein, rhodamine,boron-dipyrromethene (BODIPY), resorufin and xantone to meet this demands bywhich researchers could “see” the micro-changes in living cells and animals. Theseconventional florescent probes with high signal-to-noise ratio, high quantum yield,membrane permeability and in vivo stability could give selective response to specificbioanalytes and transduce changes of bioanalytes concentration into a change influorescence intensity. However, most of them are not ideal for deep tissue and livinganimals imaging due to their relatively short emission wavelength in visible region(λem<650nm). Molecular imaging by near-infrared (NIR) fluorescent probes isexpected to be superior and has emerged as a ‘clearer’ area for researchers to exploreto meet the unsuitable need of elucidating the biological roles of ISMRS.In contrast to toxic nanoparticles such as semiconductor quantum dots (QDs),silicon nanoparticles are low toxic even nontoxic, which make them the goodcandidate to meet the demand for the development of nontoxic NPs for bioassays,such as labeling and imaging applications. Therefore, silicon nanoparticles with thesespecial optical characteristics applied in the fluorescent biological analyticalapplications have become a wide research focus.The function of each particular metabolite may vary. Emerging studies in molecularimaging have suggested that bioanalytes have a wide range of physiological effects oncell network depending on their specific identity, the concentration, the timing and the subcellular localization of their production. Considering the complex biologicalenvironment, every particular bioanalytes needs to be monitored directly near the sitesof production and action (in situ). The conventional florescent probes could not meetthe insatiable need of researchers. Multifunctional probes and correspondingnanoprobes substantially improve the performance of imaging probes and provide anew avenue to study bioanalytes. Based on the merits of NIR fluorescent dyes withgood optical characteristics and silicon nanoparticles with good biocompatibility andsize-tunablity, we assembled two functional fluorescent nanoprobes for the directdetermination of ISMRS.Firstly, we synthesized a series of size-tunable silicon nanoparticles which are goodcarriers of fluorescent probes into living cells and a novel NIR cyanine dye that couldbe utilized to design functional fluorescent probes and target proteins, enzymes andDNA.Secondly, we assembled a novel nanoprobe for simultaneous imaging hydroxylradical and peroxynitrite by functionalizing silicon nanoparticles withHB-DTPA-Eu3+/Tb3+and3-CCA. The nanoprobe could show two differentwavelengths with two distinct coulours excited at360nm. As the analysis anddetermination of conversion between hydroxyl radical and peroxynitrite has become agreat challenge to the scientific workers. The novel functional nanoprobe resistsphotobleach, are sensitive to detect target analytes and would exhibit goodbiocompatibility.Our results provide a new avenue to detect and study hydroxylradical and peroxynitrite.Thirdly, we introduce a new synthesized cyanine as NIR fluorescent probe for ROSand a6-methoxyquinoline fluorescent probe for Cl-to silicon nanoparticle. Thenanoprobe would detect ROS with less exited energy. Furthermore, this nanoprobecould be utilized to study conversion between ROS and RCS.