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Seminar leader:-Dr. Anupama Singh Principal ScientistDiv. of Agricultural Chemicals
Speaker:-Niranjan KumarRoll No:- 20494M.Sc. (Ag. Chem.)
Molecularly Imprinted Polymers for Pesticide Detection and Controlled Delivery Approach
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Overview
Introduction History Application Limitation Case study Conclusion Future Aspects
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teMolecularly Imprinted Polymer (MIP)A Molecularly Imprinted Polymer (MIP) is a polymer that is formed using the molecular imprinting technique which leaves cavities in polymer matrix with affinity to a chosen "template" molecule.
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History of Molecularly Imprinting Techniques
Captured additives from different solvents (benzene, toluene and xylene) on the silica pore structure., M.V. Polyakov et al. 1930.
Prepared silica gels in the presence of dyes as template (methyl, ethyl, n-propyl and n-butyl orange)., Frank Dickey et al. 1949.
Prepared MIP based on covalent approach., Guenter Wulff et al. 1972.
Prepared an organic MIP using non-covalent approach., Mosbach and Arshady et al. 1981
Reported an intermediate approach .,Whitcombe et al. 1995.
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teBasic components of MIP’s
Template: memory formerFunctional monomer : specific cavity Crosslinker : morphology stabilizerInitiatorPorogenic solvent andExtraction solvent
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Covalent /Preorganized approach
Non-covalent /self-assembling approach
Imprinting Techniques
Boronate ester formation, Template removal is difficult
Hydrogen bonding between methacrylic acid and adenine, Template removal and rebinding is easy.
M. J. Whitcombe et al., 1995
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Metal-coordination interactions
Semi-covalent approachCarbonate as sacrificial spacer to place two OH groups at complementary positions.
Copper ion recognition
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tePolymerization Techniques for MIP’s
Soluble initiator & liquid monomer added, agitated & heated
High viscosity and lack of good heat transfer
Ex:- Polystyrene, polyvinyl chloride, polymethyl methacrylate.
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Monomer and initiator are soluble in solvent.
Formed polymer stays in solution form.
Viscosity build up is negligible.
Ex:- Polyacrylonitrile, PVC, Polyacrylic acid, Polyacrylamide, Polyvinyl alcohol, PMMA, Polybutadiene,etc.
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Each droplet is tiny bulk reactor.
Beads of polymer formed being insoluble in water.
Highly agitation sensitive Stabilizers used are PVA,
gelatin, cellulose Ex:- Polyvinyl acetate,
Polystyrene, Styrene-divinyl benzene copolymer beads (used for ion exchange) etc.
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Water insoluble monomer, emulsifying agents, water soluble initiator (potassium persulphate / H2O2, etc.
Emulsion of monomer in water
Viscosity remains close water
Fast polymerization rates
Ex:- Synthetic rubber, plastics.
Emulsion polymerization
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Monomer and initiator soluble in solvent
Insoluble precipitates of polymer
Polymerization degree and rate is high.
Highly pure polymer
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Therapeutics
Analytical Separations
Preparative Separations
Enzyme like
catalysts
Drug Discovery
MIP’s
SPE Chemical Sensor Bioanalysis Proteomics Food Analysis Environmental
Analysis
Drug delivery Oral absorbers Blood
Purification Therapeutic
monitoring
Library screening
Library synthesis
Enantiomer separations
Scavengers
Applications of MIP’s
Borje et al., 2005
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Controlled Delivery Approach..??
• High surface area for adsorption• Homogenous cavities for specific selection• Enhanced Chemical and Thermal stability• Fast release kinetics• Synthetic polymers are cheap, easy to synthesize• Allow Incorporation of synthetic side chains, which helps
in higher affinity, selectivity, and specificity• Reusable and can be stored for years at room
temperature.
Lorenzo et al. 2011
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Limitations
Difficulty in template removal• Collapsing of the cavity• Distorting the binding points• Incomplete removal of the template• Rupture of the cavity. Monomer and cross-linker combinations Imprinting of large bio-macromolecules Template bleeding.
Lorenzo et al., 2011
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Published: November 18, 2011
Pesticide detection
Case Study - 1
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teFluorescence spectra
Florescenceamount of template
Diazinon QD’s- MIP & NIP prepared The photoluminescence measurements were carried
out on an Model F-4600 spectrophotometer.
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teFluorescence spectra of the MIP nanosphere (120 μg/mL) colloidal solution in the presence of diazinon (450 ng/mL) after incubating for different times.
Maximum adsorption at 180 min.
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Selective, sensitive, and direct fluorescence quantification of diazinon
Florescence for Diazinon-MIP decreases linearly as the concentration increases.
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Without pre-concentration, and expensive instruments
No Diazinon was detected in tap water sample
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QDs-MIP nanospheres for Diazinon Analysis of diazinon in tap water samples, LOD:- 50 ng/mL Linearity range of 50-600 ng/mL Recoveries from the water samples 98.2% to 105.4%.
General overview of the Work
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herbicide/insecticides have been developed.
Synthesized MIP for Glyphosate, Chlorpyrifos, Diazinon
Polymers were coated (200µm) onto optical fibers.
Luminescence was excited using a model 60X-argon ion laser at 465.8 nm.
Spectra was measured using spectrometer.
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concentration, excited at 465.8 nm
Intensity Concentration of glyphosate
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polymer sensors
Curves were generated using 10 ppm solutions at pH 10.5
80% response time was 12,14,15min and 20-30 min for imprinted & non-imprinted respectively.
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Results and Discussion
Detected Glyphosate, Chlorpyrifos, Diazinon with a LOD of less than 10ppt.
Linearity range of ppt-ppm Response times of less than 15 min.
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Gao et al., 2013
Molecularly imprinted polymer microspheres for optical measurement of ultra trace non-fluorescent cyhalothrin in honey
Recovery (%) 97-104 LOD = 0.004 nM R2 = 0.99
Separation of Sudan dyes from chilli powder by magnetic molecularly imprinted polymer
Limits of detection of the four Sudan dyes are 6.2, 1.6, 4.3 and 4.5 ng/g, respectively
Relative standard deviation ranging from 4.8% to 9.1% Recovery (%) 79.9–87.8
Piao et al., 2012
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Optical Detection of α-Cyhalothrin by Core-shell Fluorescent Molecularly Imprinted Polymers in Chinese spirits
Detection limit 9.17- 60 nM/L, Recovery (%) 104.6 ± 4.8
Wang et al., 2015
Highly Permselective Membrane Surface Modification by Cold Plasma-induced Grafting Polymerization of Molecularly Imprinted Polymer for Recognition of Pyrethroid Insecticides in Fish.
Recovery (%) 81.9-101.5 Linearity Range 5.0–100.0(μg/L) LOD = 0.26(μg/kg), LOQ = 0.77(μg/kg) R2 = 0.99
Zhang et al., 2014
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Release kineticsDesorption properties of MIP’s.
1. Rate-programmed delivery: Drug diffusion from the system has to follow a specific rate profile;2. Activation-modulated delivery: The release is activated by some physical, chemical or biochemical processes; and3. Feedback-regulated delivery: The rate of drug release is regulated by the concentration of a triggering agent. When the triggering agent is above a certain level, the release is activated. This induces a decrease in the level of the triggering agent and, finally, the drug release is stopped.
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teCase Study - 3
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teSimazine MIP’s showed the controlled release of simazine in pond and thus reduces algal bloom.
Leapfrog algorithm, recommended the synthesis and testing of the following polymers :1. MIP1 (MAA-polymer) - molar ratio 1:5 simazine: MAA2. MIP2 (HEMA-polymer) - molar ratio 1:10 simazine: HEMA3. MIP 3 (EGDMA-polymer) - no monomers, only cross-linker
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3.5 mg of simazine were released from 300-mg HEMA-based MIP in 25 days
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The MAA- based polymer demonstrated strong binding towards the template.
Very slow and steady release of simazine into the water was observed, total of 0.35 mg over 25 days.
The EGDMA-based polymer was prepared without any functional monomer and as expected, the release of simazine was the largest and quickest of all the polymers.
In total, the EDGMA- based polymer released 5.2 mg of simazine in 13 days.
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Enantioselective Release of Controlled Delivery Granules Based on Molecularly Imprinted Polymers
2002, Drug Delivery, Vol. 9, No. 1 , Pages 19-30R. Suedee, T. Srichana, and T. RattananontDepartment of Pharmaceutical Chemistry, Faculty of Pharmaceutical Sciences, Prince of Songkla University, Songkla, Thailand.
Case Study - 4
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Drug/polymer ratio. Synthesized combined S-MIP for ibuprofen and
ketoprofen Drug release profiles were obtained, at 37◦C
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%ee for ibuprofen = 63.6%; %ee for ketoprofen = 13.5 by combined MIP’s granule.
%ee for ibuprofen = 43.5; %ee for ketoprofen = 10.0 by single MIP granule .
The enantioselectivity values, estimated as enantiomeric excess release percentage using the equation:
Where, S-isomer and R-isomer represent the amounts of each isomer released at a given time.
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te Mechanisms by which cyclodextrins modify drug release
from polymeric drug delivery systems Incorporation of cyclodextrins into polymeric drug
delivery systems leads to drug release by • improving the aqueous solubility of drugs• acting as wicking agents,• acting as channeling agents.1. Inclusion complexes of tretinoin with
cyclodextrins.
David et al., 2000
Soft Contact Lenses Capable of Sustained Delivery of Timolol
Synthesized Timolol imprinted hydrogels with HEMA/MAA. The release kinetics was measured at 37°C in 0.9% NaCl
(pH 5.5), phosphate buffer (pH 7.4) or artificial lacrimal fluid (pH 8).
80-90% drug release in 7-8 h As HEMA/MAA ratio increases, Timolol release also
increases. Lorenzo et al., 2002
Montassier et al., 1997
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MIP’s can be used efficiently for the rapid, specific and selective detection of pesticides.
No need of sample pre-concentration & expensive instruments.
As a tool for controlled pesticide and drug delivery in biological fluids.
As a sensors, enzyme mimics, as receptor, antibodies.
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MIP for multiple analytes.
MIP for large bio-macromolecule.
MIP for protein purification
Highly selective SPE cartridges.
Pesticide magic bullet.
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