Molecular imprinting
Molecular imprinting is a technique to create template-shaped cavities in
Molecularly imprinted materials are prepared using a template molecule and functional
In recent decades, the molecular imprinting technique has been developed for use in drug delivery, separations, biological and chemical sensing, and more. Taking advantage of the shape selectivity of the cavity, use in catalysis for certain reactions has also been facilitated.
History
The first example of molecular imprinting is attributed to M. V. Polyakov in 1931 with his studies in the polymerization of sodium silicate with ammonium carbonate. When the polymerization process was accompanied by an additive such as benzene, the resulting silica showed a higher uptake of this additive.[1] By 1949, the concept of instructional theory molecular imprinting was used by Dickey; his research precipitated silica gels in the presence of organic dyes and showed imprinted silica had high selectivity towards the template dye.[2]
Following Dickey’s observations, Patrikeev published a paper of his ‘imprinted’ silica with the method of incubating bacteria with gel silica. The process of drying and heating the silica promoted growth of bacteria better than other reference silicas and exhibited enantioselectivity.[3] He later used this imprinted silica method in further applications such as thin layer chromatography (TLC) and high performance liquid chromatography (HPLC). In 1972, Wulff and Klotz introduced molecular imprinting to organic polymers. They found that molecular recognition was possible by covalently introducing functional groups within the imprinted cavity of polymers.[4][5] The Mosbach group then proved it was possible to introduce functional groups into imprinted cavities through non-covalent interactions, thus leading to non-covalent imprinting.[6][7] Many approaches regarding molecular imprinting have since been extended to different purposes.[1]
Type of Molecular Imprinting
Covalent
In covalent imprinting, the template molecule is covalently bonded to the functional
Non-covalent
With non-covalent imprinting, interaction forces between template molecule and functional monomer are the same as the interaction forces between the polymer matrix and analyte. The forces involved in this procedure can include hydrogen bonds, dipole dipole interactions, and induced dipole forces.[1] This method is the most widely used approach to create MIPs due to easy preparation and the wide variety of functional monomers that can be bound to the template molecule. Among the functional groups, methacrylic acid is the most commonly used compound due to its ability to interact with other functional groups.[12][13] Another way to alternate the non-covalent interaction between the template molecule and polymer is through the technique ‘bite and switch’ developed by Professor Sergey A. Piletsky and Sreenath Subrahmanyam.[14] In this process, functional groups first non-covalently bond with the binding site, but during the rebinding step, the polymer matrix forms irreversible covalent bonds with the target molecule.[14][15]
Ionic/Metallic
Ionic imprinting, which involves metal ions, serves as an approach to enhance template molecule and functional monomer interaction in water.[16] Typically, metal ions serve as a mediator during the imprinting process. Cross-linking polymers that are in the presence of a metal ion will form a matrix that is capable of metal binding.[17] Metal ions can also mediate molecular imprinting by binding to a range of functional monomers, where ligands donate electrons to the outermost orbital of the metal ion.[1] In addition to mediating imprinting, metal ions can be utilized in the direct imprinting. For example, a metal ion can serve as the template for the imprinting process.[18]
Applications
One application of molecular imprinting technology is in affinity-based separations for biomedical, environmental, and food analysis. Sample preconcentration and treatment can be carried out by removing targeted trace amounts of analytes in samples using MIPs. The feasibility of MIPs in solid-phase extraction, solid-phase microextraction, and stir bar sorption extraction has been studied in several publications.[19] Moreover, chromatography techniques such as HPLC and TLC can make use of MIPs as packing materials and stationary phases for the separation of template analytes. The kinetics of noncovalently imprinted materials were observed to be faster than materials prepared by the covalent approach, so noncovalent MIPs are more commonly used in chromatography.[20]
Another application is the use of molecularly imprinted materials as chemical and biological sensors. They have been developed to target herbicides, sugars, drugs, toxins, and vapors. MIP-based sensors not only have high selectivity and high sensitivity, but they can also generate output signals (electrochemical, optical, or piezoelectric) for detection. This allows them to be utilized in fluorescence sensing, electrochemical sensing, chemiluminescence sensing, and UV-Vis sensing.[7][20] Forensic applications that delve into detections of illicit drugs, banned sport drugs, toxins, and chemical warfare agents are also an area of growing interest.[21]
Molecular imprinting has steadily been emerging in fields like
Pharmaceutical applications include selective drug delivery and control drug release systems, which make use of MIPs’ stable conformations, fast equilibrium release, and resistance to enzymatic and chemical stress.[7] Intelligent drug release, the release of a therapeutic agent as a result of a specific stimuli, has also been explored. Molecularly imprinted materials of insulin and other drugs at the nanoscale were shown to exhibit high adsorption capacity for their respective targets, showing huge potential for newfound drug delivery systems.[24] In comparison with natural receptors, MIPs also have higher chemical and physical stability, easier availability, and lower cost. MIPs could especially be used for stabilization of proteins, particularly selective protection of proteins against denaturation from heat.[25]
See also
- Molecular imprinted polymer
- Molecular recognition
References
- ^ S2CID 37702488.
- .
- ^ Patrikeev, V.; Smirnova, G.; Maksimova (1962). "Some biological properties of specifically formed silica". Nauk SSSR. 146: 707.
- ^ Wulff, G.; Sarhan, A. "The use of polymers with enzyme-analogous structures for the resolution of racemates". Angew. Chem. Int. Ed. (11): 341–346.
- S2CID 43855200.
- .
- ^ a b c d e Shah, Nasrullah (2012). "A Brief Overview of Molecularly Imprinted Polymers: From Basics to Applications". Journal of Pharmacy Research. 5: 3309.
- ^ Wulff, G.; Dederichs, R.; Grotstollen, R.; Jupe, C. (1982). "Affinity Chromatography and Related Techniques -Theoretical Aspects/Industrial and Biomedical Applications". Proceedings of the 4th International Symposium. 4: 22–26.
- S2CID 55884626.
- PMID 10997701.
- ^ Hongyuan, Yan; Row, Kyung (2006). "Characteristic and Synthetic Approach of Molecularly Imprinted Polymer". International Journal of Molecular Sciences. 7.
- .
- PMID 7894656.
- ^ PMID 11679238.
- hdl:1826/803.
- .
- PMID 26262607.
- .
- PMID 26936282.
- ^ PMID 14632031.
- ^ PMID 28350333.
- ^ WO WO1996040822A1, Domb, Abraham, "Preparation of biologically active molecules by molecular imprinting", published 1996-12-19
- PMID 21288565.
- PMID 28590908.
- .
Further reading
- Lei Ye (19 April 2016). Molecular Imprinting: Principles and Applications of Micro- and Nanostructure Polymers. CRC Press. ISBN 978-981-4364-87-4.
- Cieplak, Maciej; Kutner, Wlodzimierz (2016). "Artificial Biosensors: How Can Molecular Imprinting Mimic Biorecognition?". Trends in Biotechnology. 34 (11): 922–941. PMID 27289133.
- Iacob, Bogdan-Cezar; Bodoki, Andreea; Oprean, Luminita; Bodoki, Ede (2018). "Metal–Ligand Interactions in Molecular Imprinting".
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