Factors Affecting Peptide Interactions with Surface-Bound Microgels

Abstract

Effects of electrostatics and peptide size on peptide interactions with surfacebound microgels were investigated with ellipsometry, confocal microscopy, and atomic force microscopy (AFM). Results show that binding of cationic poly-L-lysine (pLys) to anionic, covalently immobilized, poly(ethyl acrylate-co-methacrylic acid) microgels increased with increasing peptide net charge and microgel charge density. Furthermore, peptide release was facilitated by decreasing either microgel or peptide charge density. Analogously, increasing ionic strength facilitated peptide release for short peptides. As a result of peptide binding, the surface-bound microgels displayed pronounced deswelling and increased mechanical rigidity, the latter quantified by quantitative nanomechanical mapping. While short pLys was found to penetrate the entire microgel network and to result in almost complete charge neutralization, larger peptides were partially excluded from the microgel network, forming an outer peptide layer on the microgels. As a result of this difference, microgel flattening was more influenced by the lower Mw peptide than the higher. Peptide-induced deswelling was found to be lower for higher Mw pLys, the latter effect not observed for the corresponding microgels in the dispersed state. While the effects of electrostatics on peptide loading and release were similar to those observed for dispersed microgels, there were thus considerable effects of the underlying surface on peptide-induced microgel deswelling, which need to be considered in the design of surface-bound microgels as carriers of peptide loads, e.g., in drug delivery or in functionalized biomaterials.

Translating Therapeutic Microgels into Clinical Applications

“…[ 137,147,148,149 ] Additionally, AFM can be used to measure the interaction forces between microgels with appropriate functionalities (biological recognition motifs or charges) with surface bound bioactive molecules, such as peptides and proteins as well as cells. [ 150,151 ]…”

“…[137,147,148,149] Additionally, AFM can be used to measure the interaction forces between microgels with appropriate functionalities (biological recognition motifs or charges) with surface bound bioactive molecules, such as peptides and proteins as well as cells. [150,151] Nanoindentation can be combined with fluorescence microscopy to analyze the correlation between mechanical properties and microgel functionalization or combine nanoindentation with Förster resonance energy transfer (FRET) measurements in a confocal microscope. These methods contribute to understand fundamental properties of functional microgels in biomedicine, such as molecular diffusion through the network and cellular interactions or uptake, depending on the microgel dimensions.…”

Antibacterial activities and molecular mechanism of amino‐terminal fragments from pig nematode antimicrobial peptide CP‐1

“…The physicochemical parameters and MIC results are presented in the Tables and and, respectively. There are some determinant factors that affect the antimicrobial activity of peptides, such as net charge, hydrophobicity, α‐helix propensity, and the length of the peptide . In this study, WL2 and WL3 have stronger antimicrobial activity than WL1, which is mainly due to the α‐helical propensity in the membrane environment.…”

“…The simple tandem peptide WL3 slightly loses its antimicrobial property when exposed to physiological concentrations of salts. Based on the mode of action of the antimicrobial peptides, Na + can suppress the electrostatic attraction between the peptides and the microbial membrane, as previously study . Na + has little impact on the antimicrobial activity of WL3 because WL3 possesses a higher net charge (+10), which can diminish the effect of Na + .…”

Decorating Nanostructured Surfaces with Antimicrobial Peptides to Efficiently Fight Bacteria

“…Similar effects were found for peptide loading on surface-bound microgels. 64 It is possible that the peptide incorporated between the outer hydrophilic polymer blocks in the micelle and thereby hampered flexibility. In addition, KYE28 incorporation led to a slightly increased water contact angle of 78°, that is, an increase in hydrophobicity of the surface that possibly results from the amphiphilic nature of the peptide.…”