•Abstract Pesticides; A Source of Pollution• In agriculture, pesticides are widely used by farmers to control diseases and for obtaining high yields.• Pesticide is a term used in a broader sense for chemicals, synthetic or natural, that are used for the control of insects, fungi, bacteria, weeds, rodents and other pests.
•Abstract Pesticides; A Source of Pollution• Undegraded pesticide residues may enter into the food chains through air, water and soil and cause several health problems and disrupt the ecosystems, birds, animals and human beings.• Pesticides can be carcinogenic or citogenic, they can produce bone marrow diseases, infertility, nerve disorders and immunological and respiratory diseases.
•Abstract Pesticides; A Source of Pollution As large amount of pesticides are currently being used, there is an increased interest fordeveloping rapid screeningsystems for their detection.
•Techniques used for Pesticides• The most commonly • These • In spite of their used analytical conventional advantages, methods for methods are these techniques pesticide analysis sensitive, reliable need expensive includes high and precise. instrumentation, pressure liquid require skilled chromatography, technicians, and gas chromatography are time or coupled consuming, techniques of GC- laborious and not MS. easily adoptable for field analysis.
•ELISA: Enzyme-Linked Immunosorbent Assay • ELISA is a common example of an immunoassay with the use of an enzyme tracer.More information can be added here by changing this text.
•ELISA: Enzyme-Linked Immunosorbent Assay - Steps • A test tube is then coated with a known amount of pesticide and so the pesticide is immobilized on the surface of the tube. • The antibody that recognizes and binds to that pesticide is then added. Some of the antibody binds to the immobilized pesticide.
•ELISA: Enzyme-Linked Immunosorbent Assay - Steps • The extract is then washed away, and the amount of antibody bound to the immobilized pesticide will next be measured using the enzyme tracer. • A tracer enzyme may be already attached to the antibody or may be attached by adding a second antibody (that binds to the first) conjugated with the enzyme. A solution of colourless substrate is added, which will be changed by the enzyme to a coloured product.
•ELISA: Enzyme-Linked Immunosorbent Assay - Steps • The amount of antibodies bound to the immobilized pesticide is shown by intensity of the colour; the greater the intensity, the less pesticide is in the sample. • The intensity of the colour can be measured through the use of a micro-spectrophotometer (transducer), which may be linked to a computer with data- analysing software which is then compared against a standard curve, derived from the standards, to give the amount of pesticide in the sample.
•Immunosensors for PesticidesIntroduction.Immunosensors can be distinguished from immnunoassays wherethe transducer is not an integral part of the analytical system.
•Immunosensors for Pesticides Introduction. Immunosensors are biosensors which use antibodies (Ab) or antigens (Ag) as thespecific sensing element and provide concentration- dependent signals.
•Immunosensors for Pesticides Introduction. Basically it consists of two processes, a molecular recognition process, for detecting the specific Ag–Ab binding reaction at the surfaceof receptor, and a signal-transfer process, for responding to thechanges in an electrochemical, optical, spectroscopic, or electrical parameter of thereceptor caused by the specific binding reaction.
• Surface Plasmon Resonance (SPR) Immunosensing - Steps. • SPR immunosensing involves immobilizing Ab (or Ag) through a coupling matrix to the thin gold surface on the reflecting surface of a glass prism. • Interaction between Ag and Ab on the surface will elicit a change in the refractive index resulting in variations of the light intensity.
• Surface Plasmon Resonance (SPR) Immunosensing - Steps. The detection principle relies on detecting changes in the refractive index of the solution close to the surface of the sensor chip due to shifts in mass occurring after biomolecule binding.
• Surface Plasmon Resonance (SPR) Immunosensing Monitoring of pesticide chlorpyrifos in water samples using SPR immunossesnors Spread the chlorpyrifos that is transmitted from the source on the gold coated sensing surfaceof the SPR immunosensor 1 Allow it to stick on the gold coated sensing surface to fight with the free chlorpyrifos which is binding to the antibody Thus, it will lead to a rise with concentrations of 3 2 chlorpyrifos which decrease the SPR signal
•Reflectometric Interference Spectroscopy (RIFS) - Steps. RIFS is a direct immunosensing reflectometric technique.A white incident lightwill pass the interfacebetween the different refractive indices.
•Reflectometric Interference Spectroscopy (RIFS) - Steps. The binding of the Ab (antibody) to the surface changes thethickness of the toggling layer, which causes a change in the reflectance spectrum. Therefore, the interaction process between the Ab and the hapten derivative on the surface can bedetected time-resolved.
•Advantages & Disadvantages Immunoassays, to chromatography and other detection and monitoring methods.ADVANTAGE DISADVANTAGES• Immunoassays are • Immunoassay may not be as particularly suited for water- sensitive for some soluble pesticides that are compounds as conventional generally difficult to analyse methods. using conventional analytical • Immunoassay are methods. compound-specific only, they are not suitable for multi- residue analysis.
•Advantages & Disadvantages Immunosensors, to chromatography and other detection and monitoring methods.ADVANTAGES DISADVANTAGES• Very selective and sensitive. • Limited immunosensors are• Can be carried out for commercially available at detection and monitoring in present time. the field. • Biomolecule deactivation or• Can work with complete leaking and high diffusion automation and give the resistance of the substrate/ results under a short period of biocomponent are also key timeframe. factors in the development of immunosensors that can be applied to pesticide detection.
•Advantages & Disadvantages Surface Plasmon Resonance (SPR), to chromatography and other detection and monitoring methods.ADVANTAGES DISADVANTAGES• Multi- purpose as it is very • There can be disturbances good at miniaturization, due to variations in the reliable portable refractive index or instrumentation and temperature. automation. SOLUTION• High efficiency in monitoring interactions that bind without • Through the use of a control the help of naming the surface, will ensure biomolecule. separation of signals similar to• This portable immunosensor binding events from signals based on SPR technology due to the differences in could provide a highly refractive index between the sensitive detection of sample and running buffer. pesticide analytes at nanogram per liter levels.
•ConclusionImmunosensors based on Ab–Ag combination arestrong candidates for the screening of pesticide.However, more genetically modified sensitivebiocatalysts and highly specific antibodies areneeded for the development of stable and robustbiosensors/immunosensors in the near futureapplications.
Thank You Question & Answer.References:- Biosensors for pesticides; Huangxian Ju and Vivek Babu Kandimalla- Immunosensors for Pesticides, 2008;