| Cabon dots?CDs?,luminescent nanomaterials with a diameter less than 10 nm,have unique optical properties such as tunable photoluminescence?PL?and excitation dependent emission.CDs have good properties of water solubility,biocompatibility and anti-photobleaching compared with organic small molecule and quantum dots?QDs?of CdSe,which have been used in analytical detection,biological imaging,drug delivery and other fields.However,there are still some problems of CDs in the detection and analysis,such as poor anti-interference ability and selectivity.Aptamer is an oligonucleotide DNA or RNA fragment that can specifically recognize the target.Therefore,the combination of CDs and aptamer can improve the selectivity and sensitivity of the analysis.In this paper,CDs were successfully synthesized by environmental friendly and rapid method,and combined with apatmer for the fabrication of detection probes.The fabrication of CDs probes were applied in antibiotic detection and cell imaging.The main contents are the following three parts:1.CDs were synthesized by microwave method by the usage of citric acid,ethylenediamine and glycerol as carbon precursors.Then,the combination of CDs and oxytetracycline?OTC?aptamer was developed a luminescence probe for oxytetracycline detection.The highly-selective and sensitive probes were made because OTC can quench CDs luminescence by charge transfer,and aptamer can recovery the luminescence.For the high affinity of aptamer,it is easy to make the OTC leave the surface of CDs,leading the recovery of luminscence.We also optimized the detection conditions such as aptamer sequence,buffer type,buffer pH,the detection time and so on.Under the optimum conditions,the proposal have good linearity range from 0.010 ng/mL to1.0 ng/mL in water samples,and the limit of detection is 0.002 ng/mL,and the recoveries are from 86 % to 99 %.2.In this work,CDs were synthesized by microwave method by using citric acid and urea as raw materials.For the high selectivity of kanamycin?KAA?,the KAA aptamer was applied to make a luminescent probe.Combining CDs with nucleic acid aptamer,the luminescent probe was fabricated and was used in the detection of KAA in milk by the coupled with a commerical KAA kit.The fabricated luminescent probes were characterized by infrared spectrometer,Zeta potential and mass spectrometry,and so on.The time and photo stability of KAA probes were detected.Under the optimum conditions,the developed method was applied to detect KAA in milk with the linearity ranged from 1 to 10-4ng/L,the detection limit is 5.0×10-5ng/L,and the recoveries are from 80.51 % to 92.84%.3.In this work,CDs were synthesized by microwave method by the usage of citric acid and urea,and were applied for cell imaging.The synthesized CDs have significant pH responsiveness and excellent biocompatibility.In the range of pH from 1.0 to 4.6,the optical signals were increased with the increasing of pH value,and the response remains relatively stable at pH 4.6-9.0.We also found that the charges and the diameter of CDs are also pH-dependent,and this significantly enhances the cellular internalization process inducing in tumor cell death.We hope the superior photoluminescence properties of CDs will not only for cell imaging but also for drug development. |
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