The document summarizes the use of molecularly imprinted polymers (MIPs) for pesticide detection and controlled delivery. It provides an overview of MIPs, including their history, components, imprinting techniques, applications, and limitations. It then discusses three case studies where MIPs were used: 1) fluorescent quantum dot MIPs for detection of the pesticide diazinon in water samples, 2) MIP-coated optical fibers for sensitive detection of herbicides/insecticides, and 3) controlled release of the herbicide simazine from MIP granules to prevent algal bloom in ponds.

1. ICAR–IndianAgriculturalResearchInstitute
Seminar leader:-
Dr. Anupama Singh
Principal Scientist
Div. of Agricultural Chemicals
Speaker:-
Niranjan Kumar
Roll No:- 20494
M.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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Molecularly 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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Basic components of MIP’s
Template: memory former
Functional monomer : specific cavity
Crosslinker : morphology stabilizer
Initiator
Porogenic solvent and
Extraction 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
1
2

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Metal-coordination interactions
Semi-covalent approach
Carbonate as sacrificial spacer to place two OH groups
at complementary positions.
Copper ion recognition
3
4

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Polymerization 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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 Monomer suspended in
liquid phase
 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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Why MIP for Detection and
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

17. ICAR–IndianAgriculturalResearchInstitute Fluorescence spectra
Florescence ∝ 1/amount of template
 Diazinon QD’s- MIP & NIP prepared
 The photoluminescence measurements were carried
out on an Model F-4600 spectrophotometer.

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Fluorescence 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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Calibration curves for diazinon and its analogues
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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Case Study - 2

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MIP’s for organophosphate
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.

24. ICAR–IndianAgriculturalResearchInstitute Spectral response of the glyphosate sensor to
concentration, excited at 465.8 nm
Intensity ∝Concentration of glyphosate

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Response curves for the imprinted and blank
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

29. ICAR–IndianAgriculturalResearchInstitute MIP’s as a Tool for Controlled delivery
Release kinetics
Desorption 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; and
3. 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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Case Study - 3

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Simazine 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: MAA
2. MIP2 (HEMA-polymer) - molar ratio 1:10 simazine: HEMA
3. MIP 3 (EGDMA-polymer) - no monomers, only cross-linker

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Simazine release from HEMA-based MIPs
3.5 mg of simazine were released from 300-mg
HEMA-based MIP in 25 days

33. ICAR–IndianAgriculturalResearchInstitute Results
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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Research Article
Enantioselective Release of Controlled Delivery
Granules Based on Molecularly Imprinted
Polymers
2002, Drug Delivery, Vol. 9, No. 1 , Pages 19-30
R. Suedee, T. Srichana, and T. Rattananont
Department of Pharmaceutical Chemistry, Faculty of
Pharmaceutical Sciences, Prince of Songkla
University, Songkla, Thailand.
Case Study - 4

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Release profile of the R and S enantiomers
 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.

37. ICAR–IndianAgriculturalResearchInstitute  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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Conclusions
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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Way Ahead
MIP for multiple
analytes.
MIP for large bio-
macromolecule.
MIP for protein
purification
Highly selective SPE
cartridges.
Pesticide magic bullet.

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