Phenylboronic acid, PBA

FIGURE 5.5.5 Biomolecule-responsive membranes allowing reversible open/close cycles by the conformational changes of grafted polymers, (a) Structure of copolymer comprising NIPAAm and phenylboronic acid (PBA) derivatives [66]. 

Along this line, boronic acid-based polymer complexes are sensitive to glucose as a potential insulin delivery system, presumably due to the competitive binding of glucose to boronic acids, which disrupts the boronic acid-diol complex network within the polymer matrix (Scheme 13.5) [157]. In one study, the phenylboronic acid (PBA) moiety was attached to poly(M-vinyl-2-pyrrolidone) (NVP) to form poly(NVP-co-PBA)... 

Transport via Tetrahedral Boronates. Membrane transport using boronic acid carriers was first reported in 1986 by Shinbo and co-workers who discovered that a mixture of phenylboronic acid (PBA) and trimethyloctylammonium (TOMA) chloride transported reducing monosaccharides through BLMs (75). Transport was observed to be pH sensitive, in that uphill saccharide transport could be achieved from a basic source phase into an acidic receiving phase. The transport mechanism... 

Scheme 10.3 Simplified illustration of the complexation equilibrium between the phenylboronic acid groups and glucose. Binding of glucose with PBA group in this way results in swelling of the hydrogel.

The abbreviations used are as follows TMAH = trimethylanilinium hydroxide, Bui = 1-iodobutane, PrI = 1-iodopropane, EtI = iodoethane, Mel = methyl iodide, AA -acetic anhydride, HFB = heptafluorobutyryl, HFBA = Heptafluorobutyric anhydride, TFA = trifluoroacetyl, TFAA = trifluoroacetic anhydride, PFP = pentafluoropropanyl, PPT A = pentfluoropropionic anhydride, BSTFA = N, O-bis (timethylsilyl trifluoroac-etamide), MSTFA = N-methyl-N-trimethylsilyltrifluoroacetamide, MBTFA -N-methyl-b/5 (trifluoroacetamide), TMCS = trimethylchlorosilane, TFAP = (S)-(->-N-(trifluoroacetyl) prolyl, PBA = phenylboronic acid, and CB Chloride = 4-car-bethoxyhexafluorobutyryl chloride. 

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