Resonance Light-scattering Sensor For Biomarkers Detection Using Aptamer-based DsDNA

As a new optical detection method,resonance light technology has been developing rapidly in nearly two decades.Because of the advantages of rapidity and high sensitivity,resonance light technology has been widely used for detection from small molecules,to the protein,to the virus by scholars.In combination with aptamer,this detection method used resonant light technology exhibite several advantages,including high specificity and high selectivity.To obtain the detection method of high selectivity and high sensitivity,dual-aptamer-based dsDNA was used as binding elements,three resonance light scattering experiments were carried out to detect various biomarkers,the content are summarized as follows:(1)Resonance light scattering sensor for simultaneous detection of cancer antigen 125(CA125)and stress-induced phosphoprotein 1(STIP1)using aptamer-based dsDNA.The fluorescent sensor was fabricated by carboxyfluorescein(FAM)-labelled CA125 aptamer and cyanine-5-modified STIP1 aptamer onto the surface of reduced graphene oxide(RGO),thereby quenching the fluorescence of fluorophores.When STIP1 was introduced,the fluorescence recovered.When CA125 was added,the specific binding of aptamer and CA125 triggered the release of the FAM-labeled CA125 aptamer under the effect of formaldehyde,and adsorbed on the surface of RGO which lead to fluorescence quenching of FAM.This fluorescence signals change could be used to detect CA125 and STIP1 with the lowest detectable concentration down to 0.05 U/mL and 1 ng/mL respectively.The RLS sensor was fabricated by methyl violet interact with dsDNA which is obtained by CA125 aptamer hybridized to STIP1 aptamer.The dependence of RLS intensity on targets amount was successfully utilized for simultaneous detection of CA125 and STIP1,which provide robust evidences for the presence of ovarian cancer in the early stage.This strategy is reliable,sensitive,and may form the basis for rapid screening of ovarian cancer.(2)Resonance light scattering sensor for simultaneous detection of lysozyme and ATP using aptamer-based dsDNA.The sensor was obtained by the electronic interaction between methyl violet(MV)and dsDNA.The dsDNA was obtained by hybridization of ATP aptamer and lysozyme aptamer.The resonance light scattering technique was used to detect the concentration of lysozyme and ATP.During the procedure of detection,the aptasensor works like a bidirectional switch,the corresponding side of the dsDNA will open when the target(lysozyme or ATP)“click” the aptamer,which results in corresponding RLS signal change.By the combination of the RLS technique,it is found that the changed RLS intensity was proportional to the concentration of lysozyme and ATP.The mixtures of ATP and lysozyme also met two binary function relations.The results indicated that the aptasensor could achieve simultaneous detection of ATP and lysozyme,the detection limits of ATP and lysozyme could reach 10-11 M and 10-12 M,respectively.(3)Graphene oxide as a resonance light scattering probe for thrombin detection using dual-aptamer-based dsDNA.DsDNA is obtained by hybridizing DNA1 and DNA2,which respectively consist of one aptamer of thrombin and the complementary strand of the other aptamer of thrombin.When thrombin is added,the specific binding of two aptamers to thrombin results in a complex(DNA1–thrombin–DNA2)and triggers the release of the complementary strand of two aptamers from dsDNA.The released ssDNA can be self-assembled on the surface of RGO to form a stable DNA1–thrombin–DNA2–RGO complex,which increases RLS signals.This simple and rapid method has enabled the detection of thrombin in the picomolar level in buffer and human serum samples.