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Chemomechanical Polymers as Sensors and Actuators for Biological and Medicinal Applications.

Schneider HJ, Kato K, Strongin RM - Sensors (Basel) (2007)

Bottom Line: Two different effector molecules can induce motions as functions of their concentration, thus representing a logical AND gate.Another principle relies on the fast formation of covalent bonds between an effector and the chemomechanical polymer.The speed of the responses can significantly increase by increasing the surface to volume ratio of the polymer particles.

View Article: PubMed Central - PubMed

Affiliation: FR Organische Chemie der Universität des Saarlandes, D-66041 Saarbrücken, Germany.

ABSTRACT
Changes in the chemical environment can trigger large motions in chemomechanical polymers. The unique feature of such intelligent materials, mostly in the form of hydrogels, is therefore, that they serve as sensors and actuators at the same time, and do not require any measuring devices, transducers or power supplies. Until recently the most often used of these materials responded to changes in pH. Chemists are now increasingly using supramolecular recognition sites in materials, which are covalently bound to the polymer backbone. This allows one to use a nearly unlimited variety of guest (or effector) compounds in the environment for a selective response by automatically triggered size changes. This is illustrated with non-covalent interactions of effectors comprising of metal ions, isomeric organic compounds, including enantiomers, nucleotides, aminoacids, and peptides. Two different effector molecules can induce motions as functions of their concentration, thus representing a logical AND gate. This concept is particularly fruitful with effector compounds such as peptides, which only trigger size changes if, e.g. copper ions are present in the surroundings. Another principle relies on the fast formation of covalent bonds between an effector and the chemomechanical polymer. The most promising application is the selective interaction of covalently fixed boronic acid residues with glucose, which renders itself not only for sensing, but eventually also for delivery of drugs such as insulin. The speed of the responses can significantly increase by increasing the surface to volume ratio of the polymer particles. Of particular interest is the sensitivity increase which can be reached by downsizing the particle volume.

No MeSH data available.


Selectivity between different organic effector compounds of polymer I [0.02-0.05 M phosphate buffer; the effects at pH 11 are corrected for difference between pH 7 and pH 11 alone (390 vol %)] [39a].
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f22-sensors-07-01578: Selectivity between different organic effector compounds of polymer I [0.02-0.05 M phosphate buffer; the effects at pH 11 are corrected for difference between pH 7 and pH 11 alone (390 vol %)] [39a].

Mentions: Relatively large differences in swelling promoted by various organic compounds have been observed with polymers such as I. They can be understood and planned on the basis of interaction mechanisms known from supramolecular chemistry. As indicated in Scheme 2, the ethylendiamine (ene) units allow not only metal chelation and pH-dependent protonation, but also hydrogen bonding as well as N+ cation-π effects. That the latter play an essential role is clear from the large chemomechanical effects observed only when aryl units are present in the effector molecule: the saturated cyclohexane-carboxylate has, within error, no effect in contrast to the nearly isosteric benzoic acid (Scheme 8) [39a]. That electrostatic attraction, or ion pairing with the cationic N+ sites in I is an additional prerequisite for any size changes of the gel is evidenced by the inactivity of electroneutral compounds. Finally, the alkyl groups introduced into polymer I provide for lipophilic interactions, which vary among the different organic moieties of the effectors. In consequence, not only nucleotides (see Scheme 7) but even structural isomers such as different benzene dicarboxylicacids can be distinguished (Scheme 8).


Chemomechanical Polymers as Sensors and Actuators for Biological and Medicinal Applications.

Schneider HJ, Kato K, Strongin RM - Sensors (Basel) (2007)

Selectivity between different organic effector compounds of polymer I [0.02-0.05 M phosphate buffer; the effects at pH 11 are corrected for difference between pH 7 and pH 11 alone (390 vol %)] [39a].
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3814870&req=5

f22-sensors-07-01578: Selectivity between different organic effector compounds of polymer I [0.02-0.05 M phosphate buffer; the effects at pH 11 are corrected for difference between pH 7 and pH 11 alone (390 vol %)] [39a].
Mentions: Relatively large differences in swelling promoted by various organic compounds have been observed with polymers such as I. They can be understood and planned on the basis of interaction mechanisms known from supramolecular chemistry. As indicated in Scheme 2, the ethylendiamine (ene) units allow not only metal chelation and pH-dependent protonation, but also hydrogen bonding as well as N+ cation-π effects. That the latter play an essential role is clear from the large chemomechanical effects observed only when aryl units are present in the effector molecule: the saturated cyclohexane-carboxylate has, within error, no effect in contrast to the nearly isosteric benzoic acid (Scheme 8) [39a]. That electrostatic attraction, or ion pairing with the cationic N+ sites in I is an additional prerequisite for any size changes of the gel is evidenced by the inactivity of electroneutral compounds. Finally, the alkyl groups introduced into polymer I provide for lipophilic interactions, which vary among the different organic moieties of the effectors. In consequence, not only nucleotides (see Scheme 7) but even structural isomers such as different benzene dicarboxylicacids can be distinguished (Scheme 8).

Bottom Line: Two different effector molecules can induce motions as functions of their concentration, thus representing a logical AND gate.Another principle relies on the fast formation of covalent bonds between an effector and the chemomechanical polymer.The speed of the responses can significantly increase by increasing the surface to volume ratio of the polymer particles.

View Article: PubMed Central - PubMed

Affiliation: FR Organische Chemie der Universität des Saarlandes, D-66041 Saarbrücken, Germany.

ABSTRACT
Changes in the chemical environment can trigger large motions in chemomechanical polymers. The unique feature of such intelligent materials, mostly in the form of hydrogels, is therefore, that they serve as sensors and actuators at the same time, and do not require any measuring devices, transducers or power supplies. Until recently the most often used of these materials responded to changes in pH. Chemists are now increasingly using supramolecular recognition sites in materials, which are covalently bound to the polymer backbone. This allows one to use a nearly unlimited variety of guest (or effector) compounds in the environment for a selective response by automatically triggered size changes. This is illustrated with non-covalent interactions of effectors comprising of metal ions, isomeric organic compounds, including enantiomers, nucleotides, aminoacids, and peptides. Two different effector molecules can induce motions as functions of their concentration, thus representing a logical AND gate. This concept is particularly fruitful with effector compounds such as peptides, which only trigger size changes if, e.g. copper ions are present in the surroundings. Another principle relies on the fast formation of covalent bonds between an effector and the chemomechanical polymer. The most promising application is the selective interaction of covalently fixed boronic acid residues with glucose, which renders itself not only for sensing, but eventually also for delivery of drugs such as insulin. The speed of the responses can significantly increase by increasing the surface to volume ratio of the polymer particles. Of particular interest is the sensitivity increase which can be reached by downsizing the particle volume.

No MeSH data available.