Poly imprinted

Several selective interactions by MIP membrane systems have been reported. For example, an L-phenylalanine imprinted membrane prepared by in-situ crosslinking polymerization showed different fluxes for various amino acids [44]. Yoshikawa et al. [51] have prepared molecular imprinted membranes from a membrane material which bears a tetrapeptide residue (DIDE resin (7)), using the dry phase inversion procedure. It was found that a membrane which contains an oligopeptide residue from an L-amino acid and is imprinted with an L-amino acid derivative, recognizes the L-isomer in preference to the corresponding D-isomer, and vice versa. Exceptional difference in sorption selectivity between theophylline and caffeine was observed for poly(acrylonitrile-co-acrylic acid) blend membranes prepared by the wet phase inversion technique [53]. 

An early example of an MIP-QCM sensor was a glucose monitoring system by Malitesta et al. (1999). A glucose imprinted poly(o-phenylenediamine) polymer was electrosynthesized on the sensor surface. This QCM sensor showed selectivity for glucose over other compounds such as ascorbic acid, paracetamol, cysteine, and fructose at physiologically relevant millimolar concentrations. A unique QCM sensor for detection of yeast was reported by Dickert and coworkers (Dickert et al. 2001 Dickert and Hayden 2002). Yeast cells were imprinted in a sol-gel matrix on the surface of the transducer. The MIP-coated sensor was able to measure yeast cell concentrations in situ and in complex media. A QCM sensor coated with a thin permeable MIP film was developed for the determination of L-menthol in the liquid phase (Percival et al. 2001). The MIP-QCM sensor displayed good selectivity and good sensitivity with a detection limit of 200 ppb (Fig. 15.7). The sensor also displayed excellent enantioselectivity and was able to easily differentiate the l- and D-enantiomers of menthol. 

Nickel AML, Seker E, Ziemer BP, Ellis AB. Imprinted poly (acrylic acid) films on cadmium selenide. A composite sensor structure that couples selective amine binding with semiconductor substrate photoluminescence. Chem Mater 2001 13 1391-1397. 

Oral E, Peppas NA. Hydrophilic molecularly imprinted poly(hydroxyethyl-methacrylate) polymers. J Biomed Mater Res A 2006 78 205 -210. 

Ulyanova YV, Blackwell AE, Minteer SD. Poly(methylene green) employed as molecularly imprinted polymer matrix for electrochemical sensing. Analyst 2006 131 257-261. 

Figure 2 Typical PL enhancements due to exposure to amines (a) etched n-CdSe surface exposed to ammonia (b) etched w-CdSe surface exposed to trimethylamine (c) n-CdSe coated with a trimethylamine-imprinted PAA film exposed sequentially to ammonia and trimethylamine and (d) n-CdSe coated with an ammonia-imprinted poly(acrylic acid) (PAA) film exposed sequentially to ammonia and ttimethylamine. Nitrogen gas was used as the reference ambient between exposures to the amine-containing ambients with the indicated partial pressures. Samples were excited at 633 nm and the PL was monitored at 720 nm.

Preformed polymers can also be employed to prepare imprinted core-shell particles [143]. The group of Chang recently prepared a poly(amic acid) bearing oestrone as a template molecule covalently bound to the polymer through a urethane linker (see Fig. 2). A layer of this polymer was subsequently deposited on silica particles (10 pm diameter) prefunctionalised with amino groups at their surface. Thermal imidisation of the polymer yielded finally a polyimide shell (thickness about 100 nm) on the silica particles. Subsequent template removal yielded the imprinted cavities, which exhibited selective rebinding of oestrone in HPLC experiments. 

The group of Ciardelli prepared MIP nanoparticles imprinted with theophylline or caffeine by precipitation polymerisation and coated them onto a poly-MMA-co-AA membrane (Fig. 18) [217, 255, 256]. 

The first work in this field was probably that of Piletsky et al. [84] that described a competitive FILA for the analysis of triazine using the fluorescent derivative 5-[(4,6-dichlorotriazin-2-yl)amino]fluorescein. The fluorescence of the supernatant after incubation was proportional to the triazine concentration and the assay was selective to triazine over atrazine and simazine. The same fluorescent triazine derivative was applied to competitive assays using atrazine-imprinted films [70]. To this end an oxidative polymerization was performed in the presence of the template, the monomer(s) 3-thiopheneboronic acid (TBA) or mixtures of 3-amino-phenylboronic acid (APBA) and TBA (10 1) in ethanol-water (1 1 v/v) where the template is more soluble. The polymers were grafted onto the surface of polystyrene microplates. The poly-TBA polymers yielded a detection limit of 8 pM atrazine whereas for the poly-TBA-APBA plates it was lowered to 0.7 pM after 5 h of incubation. However, a 10-20% decrease in the polymer affinity was observed after 2 months. 

Fang and co-workers [115] have reported a flow injection chemiluminescence assay for the detection of maleic hydrazide (MH). The imprinted poly(MAA-co-EDMA) polymer selectively retained the herbicide that was further treated with alkaline luminol-potassium periodate to produce a strong CL signal. Upon reaction, the absorbed MH was destroyed and removed by the flowing solution. The polymer was reused up to ten times and the linear response was between 3.5 x 10 and 5.0 x 10 2 mg mL-1 with a detection limit of 6.0 x 10 5 mg mL-1. The CILA flow injection system was used for the analysis of potato and onion samples spiked with 1.0, 2.0, and 4.0 x 10-3 mg mL-1 of MH. Recoveries ranged from 98% to 103% (RSD 2.3%), demonstrating the successful application of the method. 

Byme et al. [124] have shown the possibility of creating imprinted polymer ordered micropattems, of a variety of shapes and dimensions, on polymer and silicon substrates using iniferters and photopolymerization. They applied this approach to the recognition of D-glucose using copolymer networks containing poly(ethylene glycol) and functional monomers such as acrylic acid, 2-hydro-xyethyl methacrylate, and acrylamide. 

Molecular imprinting has been used to devise a chemosensor for L-nicotine (Table 6) [178]. For that, poly(methacrylic acid) (PMA) beads, imprinted with the L-nicotine template in chloroform, were incorporated in a film of the conjugated polymer, OCiC10-PPV. EIS has then been utilized for the L-nicotine determination in the 1-10 nM concentration range. This MIP chemosensor showed predominant affinity towards L-nicotine over a structurally related L-nicotine metabolite, L-cotinine. Similarly, the polydopamine-imprinted film prepared by electropolymerization in the phosphate buffer (pH = 7.4) has been used to devise a chemosensor for L-nicotine with LOD of 0.5 pM (Table 6) [106]. This LOD is still much higher than that reported for other L-nicotine determination methods based on MIPs, such as SPE combined with differential pulsed elution, which was 6 nM [31]. 

An imprinted poly[tetra(o-aminophenyl)porphyrin] film, deposited on a carbon fibre microelectrode by electropolymerization, was used for selective determination of dopamine [208] in the potential range of —0.15 to 1.0 V. This chemosensor has been used successfully for dopamine determination in brain tissue samples. The dopamine linear concentration range extended from 10 6 to 10-4 M with LOD of 0.3 pM. However, this LOD value is very high compared to that of the dopamine voltammetric detection using polyaminophenol MIPs prepared by electropolymerization [209]. Dopamine was determined by CV and DPV at concentrations ranging from 2 x 10 s to 0.25 x 10 6 M with LOD of 1.98 nM. This LOD value is lower than that of PM dopamine detection [133]. 

FIGURE 17 Chromatograms of the chiral resolution of Z-tyrosine-OH on Z-(S)-tyrosme-OH-imprinted poly(pentaerythritol triacrylate-co-methylmethacrylate) CSP using chloroform-acetic acid (66 4, v/v) as the mobile phase. (From Ref. 8.)... 

In spite of the development of more successful and reliable CSPs (Chaps. 2-8), these miscellaneous types of CSP have their role in the field of the chiral resolution also. The importance of these CSPs ties in the fact that they are readily available, inexpensive, and economic. Moreover, these CSPs can be used for some specific chiral resolution purpose. For example, the CSP based on the poly(triphenylmethyl methacrylate) polymer can be used for the chiral resolution of the racemic compounds which do not have any functional group. The CSPs based on the synthetic polymers are, generally, inert and, therefore, can be used with a variety of mobile phases. The development of CSPs based on the molecularly imprinted technique has resulted in various successful chiral resolutions. The importance and application of these imprinted CSPs lies in the fact that the chiral resolution can be predicted on these CSPs and, hence, the experimental conditions can be designed easily without greater efforts. Because of the ease of preparation and the inexpensive nature of these CSPs, they may be useful and effective CSPs for chiral resolution. Briefly, the future of these types of CSP, especially synthetic polymers and polymers prepared by the molecularly imprinted technique, is very bright and will increase in importance in the near future. 

Fig. 23 Fabrication procedure for microstructured waveguide a fabrication of waveguid-ing film including imprinted surface grating, b fabrication of support, and c assembly of film and support into final waveguide. PDMS poly(dimethylsiloxane) [36]...

Chen, Y.H., Chen, S.H., Analysis of DNA fragments by microchip electrophoresis fabricated on poly(methyl methacrylate) substrates using a wire-imprinting method. Electrophoresis 2000, 21, 165-170. 

Henry, A.C., Waddell, E.A., Shreiner, R., Locascio, L.E., Control of electroosmotic flow in laser-ablated and chemically modified hot imprinted poly(ethylene tereph-thalate glycol) microchannels. Electrophoresis 2002, 23, 791-798. 

PEDOT PEELS PEG PEG-Si PEI PEO PEP PER PET PG PG-zb Ph phim PHMA PI pia PIXIES poly-(3,4-ethylenedioxythiophene) parallel electron energy loss spectroscopy poly(ethylene glycol) 2-[methoxypoly(ethyleneoxy)propyl]trimethoxysilane poly(ethylene imine) poly(ethylene oxide) poly(ethylene-aZf-propylene) photoelectrorheological (effect) positron emission tomography adaptor protein G Fc domain of PG phenyl benzimidazolate poly(w-hexyl methacrylate) polyisoprene V-4-pyridyl isonicotinamide protein imprinted xerogels with integrated emission sites... 

Electropolymerization can also be used for the design of molecularly imprinted polymers (MIPs), capable of interacting with the analyte (template) molecule with high affinity and specificity (103,104). This is accomplished by electropolymerizing polypyrrole, polyaniline, or poly(o-phenylenediamine) in the presence of the analyte (template) molecule. At the end of the polymer-... 

To use this method for the preparation of imprinted colloids, Whitcombe et al. applied it during the shell preparation. They synthesized a copolymer network shell consisting of poly(EGDMA-co-cholesteryl (4-vinyl)phenyl carbonate) using a variety of different seed particles to build the polymer core [26]. The seed particles used were 30-45 nm in diameter and the imprinted p(EGDMA-co-CVPC) shell resulted to a thickness of about 15 nm (Fig. 3). The specific BET surface area of the core-shell particles was typically 80 m2 g... 

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