logo SBA

ETD

Digital archive of theses discussed at the University of Pisa

 

Thesis etd-10092021-144555


Thesis type
Tesi di dottorato di ricerca
Author
POMA SAJAMA, NOEMI VIOLETA
URN
etd-10092021-144555
Thesis title
Development of electrochemical sensors for microbial biofilm and protease activity detection
Academic discipline
CHIM/01
Course of study
SCIENZE CHIMICHE E DEI MATERIALI
Supervisors
tutor Prof. Di Francesco, Fabio
tutor Prof.ssa Tavanti, Arianna
Keywords
  • biofilm
  • electrochemistry
  • proteolytic activity
Graduation session start date
14/10/2021
Availability
Withheld
Release date
14/10/2024
Summary
Chronic wounds affect a large portion of population worldwide and significantly impact the health system and the patient’s quality of life. Biofilm formation in chronic wounds is associated to the wound healing delay. In addition high levels of protease activity further contribute to the wound chronicization, as proteases degrade the components of the extracellular matrix.
Electrochemical sensing systems are promising tools as they combine high sensitivity, fast response-time, low cost, and potential for miniaturization. This study was aimed to the development of two electrochemical sensors for the biofilm monitoring and protease activity assessment, using potentiometry and voltammetry as transduction methods.
A potentiometric, low-cost, flexible, graphenic sensor was developed. This proved to be able to monitor in real-time the growth of Gram-negative (Escherichia coli and Pseudomonas aeruginosa) and Gram-positive (Staphylococcus aureus) bacterial species. The OCP value decreased over time as bacteria accumulated on the sensor surface, displaying a significant negative correlation with respect to the bacterial growth.
The development of a voltametric sensor for the detection of protease activity was also been afforded. The protease biosensor used gelatin loaded with a redox mediator as the sensing layer. The proteolytic action and consequent gelatin degradation caused the release of redox mediator and made the electron transfer process more difficult, leading to a decrease of the current peak (ip) value as measured by AC voltammetry. The system response upon gelatin degradation was negatively and significantly correlated to the response measured by the standard azocasein assay.
File