Binding of Adenosine to Pendant Phenylboronate Groups of Thermoresponsive Copolymer: a Quantitative Study

Abstract

Binding of adenosine to the thermosensitive copolymer of N-isopropylacrylamide and 3-(acrylamido)aminophenylboronic acid (82:18, Mn = 47,000 g . mol(-1)) was studied by equilibrium dialysis at 22 degrees C and 37 degrees C, in a 0.1 M glycine buffer containing 0.1 M NaCl at pH 9.2. The copolymer exhibited a the phase transition temperature (T(p)) of 26.5 degrees C under the above conditions. At 22 degrees C the binding of adenosine to the water-soluble copolymer was well described by a Langmuir model, accounting for preferential ionisation of the boronate-nucleoside complexes and, therefore, restricted reactivity of the rest of boronates. At saturation, the copolymer contained 38% of its phenylboronic acid groups in the form of complexes, whereas the association constant was 1,400 M(-1). At 37 degrees C no binding of adenosine to thermally precipitated copolymer was found, presumably owing to interaction of the phenylboronates with hydrophobic segments of polyNIPAM. At high loading of the copolymer by the reversibly bound adenosine the T(p) steeply increases with increasing fraction of the phenylboronate-adenosine complexes in the chains. The increase of the T(p) observed above the saturating adenosine concentration (>1 x 10(-3) M, 22 degrees C) very probably testifies to competition of the nucleoside with hydrophobic polyNIPAM segments for binding to the pendant phenylboronates.

Variations of wettability and protein adsorption on solid siliceous carriers grafted with poly(N-isopropylacrylamide)

“…The practical applications of carriers with polyNI-PAM grafted according to the presented technique can probably deal with thermally controlled desorption of affinity-bound adsorbates. We have recently shown [26] that some affinity interactions displayed by copolymers of NIPAM are highly temperature-sensitive. Dissociation of the affinity complexes and, therefore, elution of a target substance can be apparently triggered by a temperature shift.…”

Fabrication of boronic acid-functionalized nanoparticles via boronic acid–diol complexation for drug delivery

“…28,29 As shown in Scheme 1, the phenylboronic acids in PMAPBA could form stable complexes with diol moieties in dextran, when dextran solution was added slowly into PMAPBA solution. 28,29 As shown in Scheme 1, the phenylboronic acids in PMAPBA could form stable complexes with diol moieties in dextran, when dextran solution was added slowly into PMAPBA solution.…”

Interaction of sugars, polysaccharides and cells with boronate‐containing copolymers: from solution to polymer brushes

“…For estimation of phase transition temperature (T P ), the linear, low-temperature parts of thermoprecipitation curves were extrapolated to zero optical densities so that their crossing points with abscissa gave T P . (see Ivanov et al, 2005a) The calculation of T P made by extrapolation of thermoprecipitation curves gave the T P value independent of heating rate, for heating rates equal or lower than 0.1258C/min.…”

“…The multivalent character of the BCC interaction with diol moieties of interacting polymeric counterpart has been recently proven in our group . The equilibrium parameters of complex formation between the pendant PBA and individual nucleoside molecules have been quantitatively characterized (Ivanov et al, 2005a). At the same time, the sugar specificity of BCC as bioaffinity reagents with lectin-like functions has been considered up to now in very few studies (Uchimura et al, 2001;Shiomori et al, 2004).…”