Throughout their lifecycle, petroleum-based plastics are associated with many environmental problems, including greenhouse gas emissions, persistence in marine and terrestrial environments, pollution, etc. On the other hand, bioplastics form a rapidly growing class of polymeric materials that are commonly presented as alternatives to conventional petroleum-based plastics. However, bioplastics also have been linked to important environmental issues such as greenhouse gas emissions and unfavorable land use change, making it necessary to evaluate the true impact of bioplastic use on the environment. Still, while many reviews discuss bioplastics, few comprehensively and simultaneously address the positives and negatives of bioplastic use for the environment. The primary focus of the present review article is to address this gap in present research. To this end, this review addresses the following questions: (1) what are the different types of bioplastics that are currently in commercial use or under development in the industry; (2) are bioplastics truly good for the environment; and (3) how can we better resolve the controversial impact of bioplastics on the environment? Overall, studies discussed in this review article show that the harms associated with bioplastics are less severe as compared to conventional plastics. Moreover, as new types of bioplastics are developed, it becomes important that future studies conduct thorough life cycle and land use change analyses to confirm the eco-friendliness of these new materials. Such studies will help policymakers to determine whether the use of new-generation bioplastics is indeed beneficial to the environment.
RationaleWe report the unsolved molecular structure of the complex biopolymer sporopollenin exine extracted from Lycopodium clavatum pollen grains.MethodsTOF‐SIMS and CID‐MS/MS, MALDI‐TOF‐MS and CID‐TOF/TOF‐MS/MS were used for the analysis of this complex biopolymer sporopollenin exine extracted from Lycopodium clavatum pollen grains. Solid‐state 1H‐ and 13C‐NMR, 2D 1H‐1H NOESY, Rotor‐synchronized 13C{1H} HSQC, and 13C{1H} multi CP‐MAS NMR experiments were used to confirm the structural assigments revealed by MS and MS/MS studies. Finally, high‐resolution XPS was used to check for the presence of aromatic components in sporopollenin.ResultsThe combined MS and NMR analyses showed that sporopollenin contained poly(hydroxy acid) dendrimer‐like networks with glycerol as a core unit, which accounted for the sporopollenin empirical formula. In addition, these analyses showed that the hydroxy acid monomers forming this network contained a β‐diketone moiety. Moreover, MALDI‐TOF‐MS and MS/MS allowed us to identify a unique macrocyclic oligomeric unit composed of polyhydroxylated tetraketide‐like monomers. Lastly, high‐resolution X‐ray photoelectron spectroscopy (HR‐XPS) showed the absence of aromaticity in sporopollenin.ConclusionsWe report for the first time the two main building units that form the Lycopodium clavatum sporopollenin exine. The first building unit is a macrocyclic oligomer and/or polymer composed of polyhydroxylated tetraketide‐like monomeric units, which represents the main rigid backbone of the sporopollenin biopolymer. The second building unit is the poly(hydroxy acid) network in which the hydroxyl end groups can be covalently attached by ether links to the hydroxylated macrocyclic backbone to form the sporopollenin biopolymer, a spherical dendrimer. Such spherical dendrimers are a typical type of microcapsule that have been used for drug delivery applications. Finally, HR‐XPS indicated the total absence of aromaticity in the sporopollenin exine.
RationaleWe report the top‐down lignomic analysis of the virgin released lignin (VRL) small oligomers obtained from French Oak wood.MethodsWe have used MALDI‐TOF‐MS in the negative ion mode for the analysis of the complex mixture of lignin oligomers extracted from French Oak wood. High‐energy CID‐TOF/TOF‐MS/MS analyses were used to support the postulated precursor ion structures.ResultsTwenty compounds were identified using MALDI‐TOF‐MS/MS of the VRL extracted from French Oak wood: seven tricin derivatives and/or flavonoids, three syringylglycerol derivatives, two syringol derivatives, two flavonolignin derivatives, and six miscellaneous compounds: luteoferol, lariciresinol isomer, 5‐hydroxy guaiacyl derivative, syringyl ‐C10H10O2 dimer, trihydroxy benzaldehyde derivative, and aryl tetralin lignan derivative. Most of the identified compounds were in the form of carbohydrate and/or shikimic acid complexes.ConclusionsThe analysis of this complex mixture led to the identification of a series of lignin dimers, novel lignin‐carbohydrate complexes (LCC), and unique tricin derivatives linked to different types of carbohydrates and shikimic acid moieties. This finding supports the presence of lignin‐carbohydrate complexes in the isolated VRL. These analyses also showed that French Oak lignin is abundant in syringol moieties present in the lignin syringyl units or tricin derivatives. Moreover, the identification of some lignin‐carbohydrate and/or flavonoid‐shikimic acid complexes could provide new insight into the relationship between the biosynthesis of lignin and tricin.
Rationale We report for the first time the top‐down lignomic analysis of the virgin released lignin (VRL) oligomers obtained from the Saudi date palm wood (SDPW), using a matrix‐assisted laser desorption/ionization time‐of‐flight/time‐of‐flight (MALDI‐TOF/TOF) instrument. In addition, we are proposing new collision‐induced dissociation tandem mass spectrometry (CID‐MS/MS) fragmentation routes for this series of unreported VRL oligomers. Methods We have used direct MALDI‐TOF‐MS analysis of the mixture of lignin oligomers without any chromatographic pre‐separation. High‐energy CID‐MS/MS analyses were used to confirm the precursor ion structures. Results Six protonated lignin oligomer molecules were identified: [C19H24O8 + H]+ as H(8‐O‐4')G; [C50H52O19 + H]+ as H(8‐O‐4')H(8‐O‐4'')S(8‐O‐4''')S(8‐O‐4'''')G; [C58H54O18+ H]+ as H(8‐O‐4')H(8‐O‐4'')H(8‐O‐4''')G(8‐O‐4'''')S(8‐O‐4''''')G; [C58H54O19 + H]+ as H(8‐O‐4')H(8‐O‐4'')H(8‐O‐4''')S(8‐O‐4'''')S(8‐O‐4''''')G; [C61H68O25 + H]+ as H(8‐O‐4')G(8‐O‐4'')G(8‐O‐4''')S(8‐O‐4'''')S(8‐O‐4''''')G; and [C61H68O26 + H]+ as C(8‐O‐4')G(8‐O‐4'')G(8‐O‐4''')S(8‐O‐4'''')S(8‐O‐4''''')G units (H = coniferyl, S = sinapyl, and G = p‐coumaryl). Two distonic cations were identified as [C39H43O15 + H]+• and [C40H43O16 + H]+• deriving from two tetrameric lignin oligomers. The high‐energy MS/MS analyses allowed the confirmation of the proposed structures of this series of lignin oligomers. Conclusions To our knowledge, this is the first elucidation of the lignin structure of the Saudi seedling date palm wood that was accomplished using a top‐down lignomic strategy that has not previously been published. The complex high‐energy CID‐MS/MS fragmentations presented herein are novel and have never been described before.
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