The Functional Nucleic Acid Aptamers For Live Cell Imaging And Targeted Cancer Therapies

With the development of life science and medical technology,people's demands for quality of life are gradually increasing.It has become a critical development direction for current life science and medical technology to access biological information sufficiently to explore the nature of various life phenomena and early diagnosis of diseases.Among them,researches based on functional nucleic acid aptamers in the live cell imaging and theragnostic have attracted many attentions.Aptamer is a short nucleic acid molecule with the ability to bind with a specific target molecule,selected by systematic evolution of ligands by exponential enrichment(SELEX)from a random nucleic acid library.Aptamers can form specific two-dimensional or three-dimensional structures under certain conditions,thus binding biological targets specifically,and have good application prospects in the fields of living cell imaging,drug delivery,tumor diagnosis and therapy.As a sensor,it is possible to detect cellular molecules easily,quickly and sensitively.The combination with the anticancer drug can enhance the ability of the drug earrier to actively target into the cell or tissue,thereby effectively releasing the drug to a specific site,realizing the targeted delivery of the drug,greatly reducing the toxic side effects of the drug.Based on the advantages of functional nucleic acid aptamers,we have designed several applications for live cell imaging and targeted cancer therapy.The specific contents are follows:1.Aptamer sensor for live cell imaging was developed to monitor the release of cadmium ions from quantum dots.Cadmium-containing quantum dots are widely used as novel inorganic fluorescent nanomaterials,but the cytotoxicity caused by the release of cadmium ions(Cd2+)from quantum dots in biological applications cannot be ignored.A Cd2+ aptamer sensor is applied to detect the release of cadmium ions from quantum dots.The sensitivity,selectivity and stability of the aptamer sensor for the detection of quantum dot Cd2+ release was evaluated in vitro.Finally,the Cd2+release process of quantum dots was detected in live cell imaging.2.Photo-regulated ATP aptamer sensor for live cell imaging to the monitoring of mitochondrial ATP was constructed.Mitochondria is an energy plant in cell,providing energy for cell biological activities.The positive charged nanoparticle DQAsomes were used to load the photo-regulated ATP aptamer sensors to form the DQAsome/sensor complexes,which could target mitochondria to monitor the fluctuation of ATP.The photocleavable group on sensor could prevent sensors,activation before reaching mitochondria.3.Aptamer-antisense oligonucleotide chimera was used to target cancer cells for silencing galectin-1 gene.Galectin-1 plays an important role in many biological processes,and its overexpression may cause tumor metastasis.Due to the better stability of antisense oligonucleotides than siRNA,we constructed a chimera of aptamer-antisense oligonucleotide for silencing galectin-1 gene specifically.The chimera could target the nucleolin on cancer cell surface through aptamer and enter into cell by caveolin-mediated endocytosis pathway,resulting the silence of galectin-1 gene.4.Aptamer-integrated ?-Gal liposome as a bispecific agent for cancer immunotherapy was developed.The bispecific ?-Gal liposome was constructed by self-assembling AS1411 aptamers into the ?-Gal containing liposome,allowing the liposomes to recognize the anti-Gal antibody while targeting the nucleolin overexpressing cancer cells.Then the complement cascade was activated to produce the chemotactic peptides of C3a and C5a,which could induce the migration of macrophages and natural killer cells to the liposomes,initiating the antibody-dependent cell mediated cytotoxicity.