Molecularly imprinted polymer Molecular similarity

Molecularly imprinted composite membranes have been developed based on the functionalisation of a commercial membrane with an MIP in order to improve the mechanical stability of the imprinted polymer phase, similarly to the preparation of MIP composite beads, discussed in Sect. 2.2.2. 

Figure 20-23 (a) Surface plasmon resonance spectrum of sensor coated with molecularly imprinted polymer that selectively binds NAD+. (b) Response of sensor to four similar molecules shows largest response to NAD+, which was the template for polymerization. [From O. A. Raitman. V. I. Chegel, a B. Kharitonov. M. Zayats. E. Katz, and I. Winner. Analysis of NAD(P) and NAD(P)H Cofactors by Means of Imprinted Polymers Associated with Au Surfaces A Surface Plasmon Resonance Study. Anal. CNm. Ada 2004,504. 101.]... 

A group of structurally similar tricyclic antidepressants was analyzed by Vallano and Remcho [131] using a molecular imprint polymer (MlP)-based... 

Therefore the development of synthetic phases that can offer similar recognition properties seems desirable. One promising way to introduce selectivity in chemical analysis is the use of molecularly imprinted polymers (MIPs) [14-16]. These can in favourable cases recognise small molecules with affinities and selectivites exceeding that of antibody-antigen and have, due to their robustness, capacity and reproducibility, potential as reusable adsorbents in assays or sample pretreatment. 

Spectroscopic sensing requires that a chromophore must be available and be influenced by the rebinding of the imprinted analyte. This can be accomplished in a variety of ways, the simplest case being when the analyte is itself a chromophore. Sensors based on intrinsic analyte chromophores can benefit from molecular imprinting by both selectivity and sensitivity enhancement. In terms of selectivity, molecules similar to the analyte are likely to have similar spectroscopic parameters that could be the source of interference in a conventional sensing strategy. The inability of an interferent to bind to the imprinted polymer allows discrimination. 

Due to the frequently poor stability (thermal, and pH) and short lifetimes of biological components, synthetic molecules with high affinity properties similar to those of biological components are being introduced. One of the most promising groups of biomimetic materials are comprises molecularly imprinted polymers (MIPs). These are becoming an important class of synthetic materials that can mimick the molecular... 

Molecularly imprinted polymer recognition units are based upon template polymerization techniques (Haupt and Mosbach 2000). The MIP recognition units are formed in the presence of a template molecule that is later leached out or extracted, thus leaving complementary cavities embedded in the Ii nal structure of the polymer. These polymers display high chemical-binding affinity for molecules with structural similarities to the template molecule. Hence, MIPs can be used to fabricate sensors... 

One of the most attractive applications would be molecularly imprinted catalysts. In principle, such catalysts could be prepared if substrate, product or transition-state analogs could be used as template molecules, since to natural catalytic antibodies are produced in a similar way. Since molecularly imprinted polymers are considered to be analogous to antibodies in that binding sites are tailor-made, catalytic antibody-like activity in imprinted polymers could also be conceived, enabling an artifi-cial catalytic antibody with the advantageous features of synthetic molecules to be produced. 

Several SP materials have been used for the extraction of FRs from aqueous samples, plasma and milk (Table 31.7). Similar materials have been used for all FRs. Typical SP materials include Ci8 and Cg bonded to porous silica, highly cross-linked poly(styrene divinylbenzene) (PS-DVB), and graphitized carbon black (GCB). It is also possible to use XAD-2 resin for extraction of various FRs, pesticides, and plastic additives from large volumes of water (100 1). The analytes can then be either eluted from the resin by acetone hexane mixture, or Soxhlet extracted with acetone and hexane. For a specific determination of diphenyl phosphate in water and urine, molecularly imprinted polymers have been used in the solid phase extraction. The imprinted polymer was prepared using 2-vinylpyridine as the functional monomer, ethylene glycol dimethacrylate as the cross linker, and a structural analog of the analyte as the template molecule. Elution was done with methanol triethylamine as solvent. Also solid phase microextraction (SPME) has been applied in the analysis of PBDEs in water samples. The extraction has been done from a headspace of a heated water sample (100°C) using polydimethylsiloxane (PDMS) or polyacryl (PA) as the fiber material. ... 

In the second, more selective, approach a class-specific extraction with molecular imprinted polymers (MIPs) can be used [43,44] however, their use in environmental analysis has been rarely reported and so far limited to pesticide analysis. For example, Turiel et al. [45] developed a method for group-selective extraction of chlorotriazines and methylyhiotyrizines and their TPs in soils, obtaining recoveries higher than 94% for chlorotriazines and 39% for prometryn. Similarly, in the study of Chapuis et al. [46], the ametryn MIP was shown to be highly class-selective for triazines and their degradation products and was appUed to the clean-up of soil extracts. 

Other SPME-IMS methods that have been reported for application to pharmaceutical or related samples include those for analysis of ephedrine in urine, meth-amphetamines in human serum, and captopril in human plasma and pharmaceutical preparations. In a method similar to SPME-IMS, testosterone was collected with a molecular imprinted polymer from urine and desorbed into an IMS. The method was validated with HPLC and determined to have a detection limit of 0.9 ng/mL with a linear dynamic range from 10 to 250 ng/mL. ... 

Figure 6 The template theophylline (T) is allowed to interact with the functional monomer methacrylic acid (M) to form a self-assembly. The monomers will interact with theophylline and will form a self-assembly complex mainly based on hydrogen bonding. This self-assembly and the positions of the functional monomers are then frozen and held in place by copolymerization with cross-linker ethyleneglycol dimethacrylate (L). This leads to a rigid polymer scaffold that retains the spatial conformation and thus the specific binding cavity of the original template. After extraction of the template, a molecularly imprinted polymer (MIP) is obtained and the imprinted cavity is able to specifically rebind the template and other, even similar structures are excluded from the binding site cavity.

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