Photoelectrochemical(PEC)biosensor is a novel analytical technology.Due to separation of excitation and output signal,PEC biosensor possessed numerous advantages such as low background signal,high sensitivity and so on,which demonstrated enormous application potential in analysis field.As is known to all,the detection sensitivity of PEC biosensor is closely related to photoelectric properties of materials.Thus,it is urgent to synthetize novel materials with excellent photoelectric conversion efficiency,which could greatly improve detection performance of PEC biosensors.With the development of material,some organic materials with photoelectric response are gradually used in construction of PEC biosensors.However,comparing with inorganic materials,the lower photoelectric conversion efficiency of organic materials limited their wide application.Therefore,how to improve the photocurrent response of organic materials has become a problem,which is needed to be solved.Designing novel organic materials not only could integrate advantages of different materials,but also could form sensitized structures,heterojunctions and so on to further accelerate transmission of carriers between materials.Therefore,photoelectric conversion of materials could be enhanced greatly,leading to extremely high photocurrent signals.In addition,diversified nucleic acid signal amplification strategies could convert a few targets into a large amount of output DNA through multi-cycles or functionalized DNA structures.The output DNA provided numerous binding sites for immobilization of signal probes,which could greatly enhance detection sensitivity of proposed PEC biosensor.Herein,by integrating high-performance organic optoelectronic materials with simple and efficient nucleic acid signal amplification strategy,we proposed a series of PEC biosensors for sensitive detection of biomarkers.The specific research content is as follows:(1)Construction of Sensitive PEC Biosensor Based on Enzyme-free triple cycles Amplification Strategy and Organic Photoelectric NanospheresIn this work,the non-sensitizer participated photoactive 3D DNA nanospheres in-situ generated on rigid planar DNA tripod was proposed as a signal probe.By integrating with enzyme-free triple cycles amplification strategy,a novel photoelectrochemical(PEC)biosensor was constructed to realize the ultra-sensitive detection of miRNA-141.First,the slight targets could be efficiently converted into numerous output DNAs through the enzyme-free triple cycles,which thus opened the hairpin at apex of planar DNA tripod on electrode to trigger the rolling cycle amplification(RCA)for in-situ producing a large amount of 3D DNA nanospheres with loading of plentiful positively charged cationic N,N-bis(2-(trimethylammonium iodide)propylene)perylene-3,4,9,10-tetracarboxydiimi-de(PDA+).Impressively,the unique rigid planar DNA tripod could not only adjust the distance among each hairpin on vertexes for simply enhancing the hybridization efficiency toward output DNA with effective improvement in the generation of 3D DNA nanospheres,but also endow the highly efficient decoration of PDA+approximated to electrode that beneficial to fast electron transport,thereby simply acquiring a low background and extremely high PEC signal without the need of sensitizers for improving detection sensitivity.As a result,the proposed approach showed a detection range from0.1 fmol·L-1 to 100 pmol·L-1 for miRNA-141,providing a novel and efficient strategy to construct ultra-sensitive PEC biosensor for potential application in early disease diagnosis.(2)Construction of Photocathodic Anti-interference PEC Biosensor Based on Cascaded Sensitized Optoelectronic Materials and DNA nanonetPhotocathodic biosensor possesses excellent anti-interference capability in bioanalysis comparing with anodic PEC biosensor,which however suffers from high electron-hole recombination rate with low photocurrent.Based on the above,a novel organic-inorganic P3HT@C60@ZnO nanosphere with cascade energy band arrangement was synthesized via a simple way,which inherited the advantages of organic high mobility for photo-generated holes and inorganic strong optical absorptivity.Specifically,the well-matched band gap endowed not only the improved life for light generated carrier and promoted separation of electron-hole pairs,but also the expansion of charge-depletion layer,significantly improving the photoelectric conversion efficiency for acquiring an extremely high photocathodic signal that increased by 30 times compared with individual materials.Accordingly,by integrating with the efficient amplification of DNA nanonet derived from clamped hybrid chain reaction(c-HCR),a sensitive photocathodic biosensor based on P3HT@C60@ZnO nanosphere was proposed for accurate detection of p53.As a result,the biosensor possessed a wide detection range from 0.1 fmol·L-1 to 10 nmol·L-1 and a low detection limit of 0.37 fmol·L-1 toward p53,offering a new avenue to construct sensitive PEC platform with superior anti-interference ability and holding a prospective application in disease diagnosis and biological analysis. |