| Abstract
| - Hybrid particles of poly(methyl methacrylate) and carboxymethylcellulose, PMMA/CMC, were attached to atomicforce microscopy cantilevers and probed against concanavalin A (ConA) films formed either on Si wafers or on CMCsubstrate. Regardless of the substrate, the approach curves showed different inclinations, indicating that the probe firsttouches a soft surface and then a hard substrate. The distance corresponding to the soft layer was estimated as 20 ±10 nm and was attributed to the CMC layers attached to the hybrid particles surfaces. Probing PMMA/CMC particlesagainst ConA adsorbed onto Si wafers yielded retract curves with a sawlike pattern. The average range of adhesionforces (maximum pull-off distance) and mean adhesion force were estimated as 100 ± 40 nm and −11 ± 7 nN,respectively, evidencing multiple adhesions between CMC sugar residues and ConA. However, upon probing againstConA adsorbed onto CMC substrates, the mean pull-off distance and mean adhesion force were reduced to 37 ± 18nm and −3 ± 1 nN, respectively, indicating that the ConA molecules immobilized onto CMC films are less availableto interact with the hybrid particle than the ConA molecules adsorbed onto Si wafers. Another set of experiments,where PMMA/CMC particle probed against ConA-covered Si wafers in the presence of mannose, showed that theaddition of mannose led to a considerable decrease in the mean adhesion force from −11 ± 7 to −3 ± 1 nN. Twohypotheses have been considered to explain the effect caused by mannose addition. The first suggested the desorptionof ConA from the substrate so that the hybrid particle would probe bare Si wafer (weak adhesion). The second proposedthe adsorption of mannose onto the ConA layer so that mannose layer would probe against another mannose layer,leading to low adhesion forces. In situ ellipsometry and capillary electrophoresis have been applied to check thehypotheses.
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