Vogel_2021_Sci.Total.Environ_773_145111

Reference

Title : Enzymatic degradation of polyethylene terephthalate nanoplastics analyzed in real time by isothermal titration calorimetry - Vogel_2021_Sci.Total.Environ_773_145111
Author(s) : Vogel K , Wei R , Pfaff L , Breite D , Al-Fathi H , Ortmann C , Estrela-Lopis I , Venus T , Schulze A , Harms H , Bornscheuer UT , Maskow T
Ref : Sci Total Environ , 773 :145111 , 2021
Abstract :

Plastics are globally used for a variety of benefits. As a consequence of poor recycling or reuse, improperly disposed plastic waste accumulates in terrestrial and aquatic ecosystems to a considerable extent. Large plastic waste items become fragmented to small particles through mechanical and (photo)chemical processes. Particles with sizes ranging from millimeter (microplastics, <5 mm) to nanometer (nanoplastics, NP, <100 nm) are apparently persistent and have adverse effects on ecosystems and human health. Current research therefore focuses on whether and to what extent microorganisms or enzymes can degrade these NP. In this study, we addressed the question of what information isothermal titration calorimetry, which tracks the heat of reaction of the chain scission of a polyester, can provide about the kinetics and completeness of the degradation process. The majority of the heat represents the cleavage energy of the ester bonds in polymer backbones providing real-time kinetic information. Calorimetry operates even in complex matrices. Using the example of the cutinase-catalyzed degradation of polyethylene terephthalate (PET) nanoparticles, we found that calorimetry (isothermal titration calorimetry-ITC) in combination with thermokinetic models is excellently suited for an in-depth analysis of the degradation processes of NP. For instance, we can separately quantify i) the enthalpy of surface adsorption delta(Ads)H = 129 +/- 2 kJ mol(-1), ii) the enthalpy of the cleavage of the ester bonds delta(EB)H = -58 +/- 1.9 kJ mol(-1) and the apparent equilibrium constant of the enzyme substrate complex K = 0.046 +/- 0.015 g L(-1). It could be determined that the heat production of PET NP degradation depends to 95% on the reaction heat and only to 5% on the adsorption heat. The fact that the percentage of cleaved ester bonds ( = 12.9 +/- 2.4%) is quantifiable with the new method is of particular practical importance. The new method promises a quantification of enzymatic and microbial adsorption to NP and their degradation in mimicked real-world aquatic conditions.

PubMedSearch : Vogel_2021_Sci.Total.Environ_773_145111
PubMedID: 33940717

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Citations formats

Vogel K, Wei R, Pfaff L, Breite D, Al-Fathi H, Ortmann C, Estrela-Lopis I, Venus T, Schulze A, Harms H, Bornscheuer UT, Maskow T (2021)
Enzymatic degradation of polyethylene terephthalate nanoplastics analyzed in real time by isothermal titration calorimetry
Sci Total Environ 773 :145111

Vogel K, Wei R, Pfaff L, Breite D, Al-Fathi H, Ortmann C, Estrela-Lopis I, Venus T, Schulze A, Harms H, Bornscheuer UT, Maskow T (2021)
Sci Total Environ 773 :145111