PMC

Structure of chitin, chitosan and protonated chitosan (water-soluble poly-electrolyte). The structures were obtained in the ChemDraw 7.0 (PerkinElmer, Waltham, MA, USA) software.

Comparison of the structure factor S(q) of the poly-electrolyte segments (red continuous line) and the counterions (blue dashed line) in a salt free polyelectrolyte solution at different solvent affinities: (a) no solvent affinity (ε_c,s/ε = ε_p,s/ε = 1); (b) strong counter-ion solvent affinity (ε_c,s/ε = 8); (c) strong polyelectrolyte solvent affinity (ε_p,s/ε = 8). The resulting S(q) of the counter-ions in the case of electrolyte solutions is included as point of reference for the case of counter-ion solvent affinity (green dot-dashed line) as illustrated (b). The charge fraction for all cases was φ = 0.032.

Normalized current traces of translocation events with (a) uncoated negatively charged NPs showing mostly enhancements (b) poly-electrolyte coated positively charged NPs showing mostly blockages. The open pore current in both figures (a) and (b) was approximately 67 nA at 800 mV. (c)Interaction between the positively charged AuNP with the negatively charge SiN membrane causes a change from the enhancement regime to the blockage regime and a significant increase in dwell time. Also notable is positive Au NP at lower potential (500 mV) has a larger dwell time than the higher potential (800 mV), which is not prominent in the negative AuNP cases.

Schematic representation of the process involved in the encapsulation of CAT into polymer multilayers using biocrystals as templates. (Steps 1, 2) stepwise deposition of poly electrolyte layers; (Step 3) Exposure of the enzyme to solutions of pH > 6 or acidic solution (pH < 4), which results in the morphology change of the polymer capsule accompanied by the solubilisation of the enzyme; (Step 4) Exposure of the enzyme to solutions of pH > 11 leads to the release of the enzyme by rupturing of the polymer capsule; (Step 5) Exposure of the encapsulated enzyme to an oxidizing solution results in the decomposition of the enzyme and thus enzyme expelled from the interior of the capsule through the polymer walls, leaving behind the hollow polymer capsules (reproduced with permission from Caruso et al. Langmuir 2000, 16, 1485–1488).