Amphiphilic hydrogels functionalized with antimicrobial peptides for wound care
Doktorsavhandling, 2023

Bacteria have the potential to cause significant harm to us when found in places where we do not want them, such as in wounds. Through the last century, the gold standard of eradicating bacteria in these cases has been with antibiotics. However, this treatment is at the risk of being severely impeded by antibiotic resistance, requiring alternative ways of dealing with bacteria. Antimicrobial peptides (AMPs) have shown promise as such an alternative with its broad-spectrum and rapid antibacterial activity, with a lower risk of inducing resistance.
The aim of this thesis was to investigate the covalent attachment of AMPs to the surface of Pluronic F127 based amphiphilic hydrogels and validate the same in vitro, in vivo, and clinically for wound care applications. A few variants of the material were created, with hydrogel discs being the most common as a convenient base for evaluation. The material was also prepared as a wound dressing where it was evaluated in a human intact skin study for a clinically relevant investigation. Furthermore, the material was also made into particles as a platform for treating deeper wounds as well as in liquid formulation or as a coating.
Overall, the AMP-functionalized hydrogels showed a potent antibacterial activity against both gram-negative and gram-positive bacteria, and some antibiotic resistant strains among them. At the same time, the materials did not show any signs of cytotoxicity against fibroblasts or erythrocytes. Furthermore, the AMP-functionalized hydrogels showed a potential to reduce the endotoxin levels released by Pseudomonas aeruginosa, a property that might assist further with combating the adverse effects of a wound infection and improve healing outcomes. The material also showed a significant antibacterial effect against the bacteria naturally present on our skin when evaluated clinically on healthy volunteers.
A main limitation behind the clinical use of AMPs is that they have a low biostability and are rapidly degraded by proteolytic enzymes. By covalently attaching the AMPs to a solid substrate they should gain steric protection against degradation. That was also the case observed for the AMPs when covalently attached to the hydrogels, as they retained their antibacterial activity for several days, both in serum, and implanted in an infected rat model. The covalent attachment of the AMPs also resulted in a contact killing mechanism, suitable for a local antibacterial effect.

infections

Antimicrobial peptides

hydrogels

wound care

lyotropic liquid crystals

antibacterial surfaces

amphiphilic polymers

surface functionalization

10:an
Opponent: Georgios Sotiriou, Karolinska Institutet, Stockholm, Sweden.

Författare

Edvin Blomstrand

Chalmers, Kemi och kemiteknik, Tillämpad kemi

Antimicrobial Peptide-Functionalized Mesoporous Hydrogels

ACS Biomaterial Science and Engineering,;Vol. 7(2021)p. 1693-1702

Artikel i vetenskaplig tidskrift

Cross-linked lyotropic liquid crystal particles functionalized with antimicrobial peptides

International Journal of Pharmaceutics,;Vol. 627(2022)

Artikel i vetenskaplig tidskrift

Clinical investigation of use of an antimicrobial peptide hydrogel wound dressing on intact skin

Journal of Wound Care,;Vol. 32(2023)p. 368-375

Artikel i vetenskaplig tidskrift

Blomstrand, E, Posch, E, Stepulane, A, Rajasekharan, A.K, Andersson, M. Antibacterial and hemolytic activity of antimicrobial peptides in solution and attached to a hydrogel surface

Blomstrand, E, Atefyekta, S, Rajasekharan, A.K, Svensson, S, Trobos, M, Thomson, P, Andersson, M. In vivo biostability and endotoxin binding properties of a hydrogel functionalized with antimicrobial peptides

Bakterier finns överallt omkring oss. För det mesta har vi en bra relation med bakterier, de finns till exempel i marken och omvandlar löv till brukbar jord, och de finns även i våra magar och bryter ned mat till näringsämnen vi kan använda. Problemet med bakterier är när de hittar till platser där de orsakar mer skada än nytta. Om till exempel för många bakterier tar sig till ett sår så kommer de att försöka sprida sig och kolonisera sårbädden. Detta leder i sin tur till en infektion. Vanligtvis behandlar vi infektioner med antibiotika, men spridningen av antibiotikaresistens har gjort att vissa infektioner blir allt svårare att behandla. Det behövs därför nya alternativ.
En fantastisk källa till inspiration är att undersöka hur naturen löser ett problem. Ett ämne som återfinns i de flesta flercelliga organismers medfödda immunförsvar är antimikrobiella peptider. Dessa peptider är specialister på att döda bakterier på ett sådant sätt att det inte skadar våra egna celler, och har mycket lägre risk att orsaka resistens. Tyvärr finns det vissa nackdelar med antimikrobiella peptider då de bryts ned snabbt i biologiska miljöer. I denna doktorsavhandling undersöks därför en metod där peptiderna binds in till ytor som skyddar peptiderna samtidigt som de fortfarande kan utöva sin bakteriedödande effekt. Detta resulterar i ett antibakteriellt material som lämpar sig för användning inom sårvård för att motverka infektioner och tillåta en naturlig läkning.

Ämneskategorier

Materialteknik

ISBN

978-91-7905-912-5

Doktorsavhandlingar vid Chalmers tekniska högskola. Ny serie: 5378

Utgivare

Chalmers

10:an

Opponent: Georgios Sotiriou, Karolinska Institutet, Stockholm, Sweden.

Mer information

Senast uppdaterat

2023-10-20