TY - JOUR
T1 - Shelf-life optimisation of plasma polymerised (2,2,6,6-tetramethylpiperidin-1-yl)oxyl (TEMPOpp) coatings; a new possible approach to tackle infections in chronic wounds
AU - Böttle, Kilian
AU - Vasilev, Krasimir
AU - Michl, Thomas Danny
PY - 2021/4
Y1 - 2021/4
N2 - Chronic wounds fail to heal and are accompanied by an ongoing infection. They cause suffering, shorten lifespans, and their prevalence is increasing. Unfortunately, the medical treatment of chronic wounds has remained unchanged for decades. A novel approach to break the biological vicious cycle is the long-lived radical (2,2,6,6-Tetramethylpiperidin-1-yl)oxyl (TEMPO). TEMPO can be plasma polymerised (TEMPOpp) into thin coatings that have antimicrobial properties. However, due to its radical nature, quenching causes it to lose effectiveness over time. Our aim in this study was to extend the shelf-life of TEMPOpp coatings using various storage conditions: Namely, room temperature (RT), room temperature & vacuum sealed (RTV), freezer temperature & vacuum sealed (FTV). We have analysed the coatings’ quality via the surface analytical methods of X-Ray Photoelectron spectroscopy (XPS) and electron paramagnetic resonance (EPR); finding marked differences among the three storage conditions. Furthermore, we have compared the antimicrobial efficacy of the stored coatings against two major bacterial pathogens, Staphylococcus aureus and Staphylococcus epidermidis, commonly found in chronic wounds. We did so both qualitatively via live/dead staining, as well as quantitatively via (2-methoxy-4-nitro-5-sulfophenyl)-5-[(phenylamino) carbonyl]-2H-tetrazolium (XTT) viability assay for up to 15 weeks in 5 weeks increments. Taken all together, we demonstrate that samples stored under FTV conditions retain the highest antimicrobial activity after 15 weeks and that this finding correlates with the retained concentration of nitroxides.
AB - Chronic wounds fail to heal and are accompanied by an ongoing infection. They cause suffering, shorten lifespans, and their prevalence is increasing. Unfortunately, the medical treatment of chronic wounds has remained unchanged for decades. A novel approach to break the biological vicious cycle is the long-lived radical (2,2,6,6-Tetramethylpiperidin-1-yl)oxyl (TEMPO). TEMPO can be plasma polymerised (TEMPOpp) into thin coatings that have antimicrobial properties. However, due to its radical nature, quenching causes it to lose effectiveness over time. Our aim in this study was to extend the shelf-life of TEMPOpp coatings using various storage conditions: Namely, room temperature (RT), room temperature & vacuum sealed (RTV), freezer temperature & vacuum sealed (FTV). We have analysed the coatings’ quality via the surface analytical methods of X-Ray Photoelectron spectroscopy (XPS) and electron paramagnetic resonance (EPR); finding marked differences among the three storage conditions. Furthermore, we have compared the antimicrobial efficacy of the stored coatings against two major bacterial pathogens, Staphylococcus aureus and Staphylococcus epidermidis, commonly found in chronic wounds. We did so both qualitatively via live/dead staining, as well as quantitatively via (2-methoxy-4-nitro-5-sulfophenyl)-5-[(phenylamino) carbonyl]-2H-tetrazolium (XTT) viability assay for up to 15 weeks in 5 weeks increments. Taken all together, we demonstrate that samples stored under FTV conditions retain the highest antimicrobial activity after 15 weeks and that this finding correlates with the retained concentration of nitroxides.
KW - Chronic wound
KW - EPR
KW - Long-lived radical
KW - Nitroxides
KW - Plasma polymer
KW - S. aureus
KW - S. epidermis
KW - Shelf-life
KW - TEMPO
KW - XTT
UR - http://www.scopus.com/inward/record.url?scp=85103578781&partnerID=8YFLogxK
UR - http://purl.org/au-research/grants/NHMRC/1122825
UR - http://purl.org/au-research/grants/NHMRC/1032738
U2 - 10.3390/antibiotics10040362
DO - 10.3390/antibiotics10040362
M3 - Article
AN - SCOPUS:85103578781
VL - 10
JO - Antibiotics
JF - Antibiotics
SN - 2079-6382
IS - 4
M1 - 362
ER -