Abstract
Bacteria biofilms in chronically infected wounds significantly increase the burden of healthcare costs and resources for patients and clinics. Because biofilms are such an effective barrier to standard antibiotic treatment, new methods of therapy need to be developed to combat these infections. Our group has demonstrated the potential of using Laser Generated Shockwaves as a potential therapy to mechanically disrupt the bacterial biofilms covering the wound. Previous studies have used rigid silica glass as the shockwave propagation medium, which is not compatible with the intended clinical application. This paper describes the exploration of five candidate flexible plastic films to replace the glass substrate. Each material measured 0.254 mm thick and was used to generate shockwaves of varying intensities. Shockwave characterization was performed using a high-speed Michelson displacement interferometer and peak stress values obtained in the flexible substrates were compared to glass using one-way nested Analysis of Variance and Tukey HSD post-hoc analysis. Results demonstrate statistically significant differences between substrate material and indicate that polycarbonate achieves the highest peak stress for a given laser fluence suggesting that it is optimal for clinical applications.
Highlights
It has been well documented that 1) chronic wound infections significantly hinder the healing process, increasing healthcare costs and consumption of resources, and 2) bacteria biofilms play an integral role in the persistence of infected wounds [1,2,3,4]
Second we focus on decay time instead of FWHM because, in the intended clinical application, the intensity of the reflected tensile wave is strongly dependent on destructive interference with the tail end of the transmitting compressive wave
Looking at the 110.14 mJ/mm2 laser drive density as an example, polycarbonate generated a peak stress of 258.75 MPa, and PVC generated a peak stress of 101.74 MPa, showing a difference of over 150 MPa
Summary
It has been well documented that 1) chronic wound infections significantly hinder the healing process, increasing healthcare costs and consumption of resources, and 2) bacteria biofilms play an integral role in the persistence of infected wounds [1,2,3,4]. When bacteria infect a wound and proliferate, they create a protective habitat to survive called a biofilm. This film is composed of an extracellular polysaccharide matrix, sometimes referred to as glycocalix or extracellular polymeric substance (EPS) [4,5,6,7]. The biofilm serves many functions that aid the survival of bacterial colonies. It is the beginning of the adhesion process for cell-cell or cell-surface interaction. It is the avenue for collecting nutrients and minerals to sustain the bacteria [8], which in the case of open wounds are likely siphoned from the underlying tissue, leading to its necrosis. Studies have shown that standard antibiotic treatments are ineffective against biofilms, requiring up to 1000 times the normal dosage to generate significant therapeutic effects, which in turn becomes toxic to the patient [9,10]
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