Membrane-Disrupting Nanofibrous Peptide Hydrogels

Abstract

Self-assembled peptide nanofibers can form biomimetic hydrogels at physiological pH and ionic strength through noncovalent and reversible interactions. Inspired by natural antimicrobial peptides, we designed a class of cationic amphiphilic self-assembled peptides (CASPs) that self-assemble into thixotropic nanofibrous hydrogels. These constructs employ amphiphilicity and high terminal charge density to disrupt bacterial membranes. Here, we focus on three aspects of the self-assembly of these hydrogels: (a) the material properties of the individual self-assembled nanofibers, (b) emergence of bulk-scale elasticity in the nanofibrous hydrogel, and (c) trade-off between the desirable material properties and antimicrobial efficacy. The design of the supramolecular nanofibers allows for higher-order noncovalent ionic cross-linking of the nanofibers into a viscoelastic network. We determine the stiffness of the self-assembled nanofibers via the peak force quantitative nanomechanical atomic force microscopy and the bulk-scale rheometry. The storage moduli depend on peptide concentration, ionic strength, and concentration of multivalent ionic crosslinker. CASP nanofibers are demonstrated to be effective against Pseudomonas aeruginosa colonies. We use nanomechanical analysis and microsecond-time scale coarse-grained simulation to elucidate the interaction between the peptides and bacterial membranes. We demonstrate that the membranes stiffen, contract, and buckle after binding to peptide nanofibers, allowing disruption of osmotic equilibrium between the intracellular and extracellular matrix. This is further associated with dramatic changes in cell morphology. Our studies suggest that self-assembled peptide nanofibrils can potentially acts as membranedisrupting antimicrobial agents, which can be formulated as injectable hydrogels with tunable material properties.

Antimicrobial and Amyloidogenic Activity of Peptides. Can Antimicrobial Peptides Be Used against SARS-CoV-2?

“…Several studies have demonstrated the formation of antibacterial nanonets by amyloids, which inhibit the spread of microbes [ 176 , 177 ]. AMPs capable of forming hydrogels with mechanical protective properties for the further proliferation of both planktonic bacterial cells and biofilms are of particular interest [ 178 , 179 ]. Using the software AGGRESCAN [ 180 ], FoldAmyloid [ 181 ], PASTA 2.0 [ 182 ] and Waltz [ 183 ], we searched for and predicted amyloidogenic regions in a sample of 300 and 499 AMPs showing activity against Gram-negative and Gram-positive bacteria, respectively ( Figure 4 ).…”

Multivalent display of chemical signals on self‐assembled peptide scaffolds

“…Coil29 (QARILEADAEILRAYARILEAHAEILRAQ-NH 2 ) Ovalbumin 257-264 3B [121] PADRE (aKXVAAWTLKAa) 3B [121] PEPvIII (LEEKKGNYVVTDH) 3B [121] PEPvIII (LEEKKGNYVVTDH)/ PADRE (aKXVAAWTLKAa) 3B [121] Ovalbumin 323-339 3B [122] E214 (Ac-KFEGTEDAVETIIQAIEA) 3B [122] Ac-(Leu) 15 -Lys J8 (Ac-QAEDKVKQSREAKKQVEKALKQLEDKVQ)/ PADRE (AKFVAAWTLKAAA-NH 2 ) 3B [123] Ac-KKFKFEFEF Tyrosinase-related protein 2 180-188 3B [124] P10 (D[KIEKRIK] 5 KWWP) LSEIKGVIVHRLEGFFLLTRILTIPQSLD/gonadotropinreleasing hormone 3B [125] STQNAIDEITNKVN 3B [125] FF03 QVVHNSYNRPAYSPG 3B [126] AP205 SpyTag/Pfs25 3B [127] Mi3 SpyCatcher/cysteine-rich protective antigen 3B [128] SAPNs αTSR/ NANP/flagellin 3B [129] Matrix protein 2/HelixC 3B [130] P27/P27A 3B [131] Ac-AAVVLLLW Human papillomavirus E7 43-57 3B [132] Lumazine synthase nanoparticles Z-domain of protein A from Aquifex aelicus/ anti-HER2 antibodies/fluorescein 3B [133] AlDox (6-maleimidocapryl hydrazone) 3B [133] Sialic acid/Alexa Fluor 488 3F [134] Polyhedron protein from Autographa californica nucleopolyhedrovirus nanoparticles Open reading frame 2 from Porcine Circovirus Type 2 3B [135] NAVISQKKK-NH 2 KKK 3C [136] Ac-K 6 (SL) 6 K 6 -NH 2 Lysine residues 3C [137] Ac-WK x (QL) y K z -NH 2 Lysine residues 3C [138][139][140] Ac-WK 2 (QL) 6 K 2 -NH 2 /Ac-H 3 (QL) 6 Melittin 3C [141] K 3 W(QL) 6 K 2 -NH 2 Lysine residues/polyethylene glycol 3C [142] Fmoc-FFE Spermine 3C [143] Nap-FFE Spermine 3C [143] Nap-FFKK Lysine residues 3C [144] FFKK Naproxen 3C [145] Nap-FFFKK Lysine residues 3C …”

Supramolecular Peptide Assemblies as Antimicrobial Scaffolds

“…While activity against planktonic cells is important, the inhibition of multicellular bacterial biofilms is a particularly attractive goal for clinical biomaterials. Kumar and colleagues described a series of cationic and amphiphilic self-assembling, β-sheet forming peptides (CASP) that contain 2-8 lysine residues in their sequence to form hydrogels that could inhibit the formation of P. aeruginosa biolfims [132]. These sequences tolerated up to six lysine residues, with CASP-K8 not able to form gels at 20 mg/mL concentrations, leading to the team further validating the anti-biofilm activity of CASP-K6.…”