The Study On The DNA Biosensor Based On MnO₂ Nanoparticles For Detecting Arthrobotrys Olisospora

Biological control of nematode pests by natural enemies has the advantages of environment-friendly,lasting efficacy,no drug resistance and so on.As the natural enemies of nematode,nematode-trapping fungi not only plays an important biological factor in controlling and regulating population,but are considered as ideal agents for controlling parasitic nematodes of plants and animals.Arthrobotrys oligospora is one of the most common and well-studied nematode-trapping fungi that can form adhesive network traps and be found in diverse soil environments.Therefore,it is important to detect A.oligospora with a sensitive,quick and portable method.Currently,the detection of A.oligospora usually is based on morphology and 18S ribosomal DNA.Electrochemical DNA biosensor has been widely used in recent years due to numerous advantages,such as high sensitivity,simplicity,low cost and possible miniaturization.However,most of DNA biosensors were used to detect bacteria and HIV,few researches were about Trichoderma harzianum.There is no report about electrochemical DNA biosensor for detection A.oligospora so far.Two kinds of DNA biosensors for detection of A.oligospora were designed in this paper.Internal Transcribed Spacer(ITS)of A.oligospora was selected as probe DNA(p-DNA).(1)An electrochemical DNA biosensor was developed that is based on a glassy carbon electrode modified with chitosan(p-DNA | chitosan | GCE).With a best DNA hybridization conditions,the biosensor was capable of detecting target DNA in the concentration range from 10-6 to 10-8 mol L-1,with a low detection limit of 10-9 mol L-1.The results show that this DNA biosensor has the potential for detecton of a specific sequence of the A.oligospora gene.(2)An electrochemical DNA biosensor was developed that is based on a glassy carbon electrode modified with MnO2 nanoparticles and chitosan(p-DNA | MnO2 |chitosan | GCE).With a best DNA hybridization conditions,the biosensor was capable of detecting target DNA in the concentration range from 10-6 to 10’9 mol L-1,with a lower detection as 10-11 mol L-1.The results show that the DNA biosensor has the potential for sensitive detection of a specific sequence of the A.oligospora gene.(3)Compared to DNA biosensor based on p-DNA | chitosan | GCE,the detection concentration range and the detection limit of DNA biosensor based on p-DNA | MrnO2 | chitosan | GCE were improved.The results indicated that MnO2 nanoparticles were a good material to develop electrochemical DNA biosensor for detecting A.oligospora.(4)The adsorption mechanism of probe DNA on electrochemical DNA biosensor based on p-DNA | MnO2 | chitosan | GCE was speculated.The active groups on surface of MnO2 nanoparticles were prontonated by acid chitosan solution.DNA phosphoric group side chain was adsorbed on surface of prontonated MnO2 nanoparticles by electrostatic attraction.The innovative place:(1)An electrochemical DNA biosensor for the detection of A.oligospora was developed.(2)The adsorption mechanism of target DNA on electrochemical DNA biosensor based on p-DNA | MnO21 chitosan | GCE was speculated.