Lipase degradation of plasticized polyvinyl chloride endotracheal tube surfaces to create nanoscale features

Abstract

Polyvinyl chloride (PVC) endotracheal tubes (ETTs) nanoetched with a fungal lipase have been shown to reduce bacterial growth and biofilm formation and could be an inexpensive solution to the complex problem of ventilator-associated pneumonia (VAP). Although bacterial growth and colonization on these nanoetched materials have been well characterized, little is known about the mechanism by which the fungal lipase degrades the PVC and, thus, alters its properties to minimize bacteria functions. This study used X-ray photoelectron spectroscopy (XPS) and attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) to better describe the surface chemistry of both unetched and lipase nanoetched PVC ETT. ATR-FTIR analysis of the unetched and treated surfaces showed a similar presence of a plasticizer. This was confirmed by XPS analysis, which showed an increase of carbon and the presence of oxygen on both unetched and nanoetched surfaces. A quantitative comparison of the FTIR spectra revealed significant correlations (Pearson’s correlation, R =0.997 [ R 2 =0.994, P <0.001]) between the unetched and nanomodified PVC ETT spectra, demonstrating similar surface chemistry. This analysis showed no shifting or widening of the bands in the spectra and no significant changes in the intensity of the infrared peaks due to the degradation of the plasticizer by the fungal lipase. In contrast, results from this study did demonstrate significantly increased nanoscale surface features on the lipase etched compared to non-etched PVC ETTs. This led to a change in surface energetics, which altered ion adsorption to the ETTs. Thus, these results showed that PVC surfaces nanoetched with a 0.1% lipase solution for 48 hours have no significant change on surface chemistry but do significantly increase nanoscale surface roughness and alters ion adsorption, which suggests that the unique properties of these materials, including their previously reported ability to decrease bacterial adhesion and growth, are due to the changes in the degree of the nanoscale roughness, not changes in their surface chemistry.

Immobilization in Ionogel: A New Way to Improve the Activity and Stability of Candida antarctica Lipase B

“…Sheldon developed a new method for enzyme immobilization as CLEA (crosslinked enzyme aggregates). The method involves the precipitation of the enzyme from aqueous buffer followed by crosslinking with glutaraldehyde of the resulting physical aggregates of enzyme molecules [ 29 , 30 ]. CLEAs are shown to be stable, recyclable catalysts exhibiting high catalyst productivities.…”

“…It could be explained by possible PVC degradation at these conditions and, consequently, releasing HCl into the medium. Very recently, lipase degradation of plasticized PVC has been studied [ 29 , 30 ]. It was reported that this degradation could yield HCl.…”

“…As regards the greenness of the process, we should remember that the primary cause of the high E factors (developed by Seldon and defined as the ratio mass waste/mass product) of most processes in the pharmaceutical industry is the high molecular complexity of APIs (active pharmaceutical ingredients), the large number of chemical steps needed to assemble the APIs from commercially available starting materials, and the use of classical stoichiometric reagents instead of catalysts [ 29 , 31 ]. From an environmental point of view, the new method proposed in this paper involves the use of immobilized biocatalysts with better properties, activity, and selectivity than the free enzyme, which increases the productivity of the process [ 30 , 32 ].…”

Selective digestive decontamination solution used as “lock therapy” prevents and eradicates bacterial biofilm in an in vitro bench-top model

“…Based on the possibility to prevent VAP, other authors have demonstrated other procedures to prevent biofilm formation. Machado et al, have recently described a novel way of preventing biofilm formation on ETT surface by nanomodifying polyvinyl with a fungal lipase [ 38 , 39 ]. They also demonstrated that these modifications reduced P. aeruginosa colonization by 2.7 log 10 [ 40 ].…”

A novel antibacterial and antifouling nanocomposite coated endotracheal tube to prevent ventilator-associated pneumonia

“…For example, photolithographic etching of the Sharklet™ micro-pattern onto a silicone ETT surface resulted in a significant decrease in the accumulation of mucus inside the ETT, both in vitro and in vivo [ 21 ]. In addition, nanorough ETTs that can decrease bacterial growth and biofilm formation have also been introduced [ 22 ]; however, their widespread use is hindered by concerns over antibiotic resistance, coating stabilities, biocompatibility, and relatively high costs. Indeed, only silver-coated ETTs have been approved as antibiofilm ETTs in the USA, and to date, these coatings have been subjected to multiple clinical trials [ 14 ].…”