80
and 2) due to their small size, the L NPs enters intracellular space. Some lignin
monophenolic compounds, e.g. cinnamaldehyde, consumes adenosine triphosphate
(ATP) energy by infiltrating the bacteria and decreasing the intracellular pH. The
combination of these two mechanisms leads to cell death. Yang et al. (2018a) produced polyvinyl alcohol/Cs (PVA/Cs) hydrogels containing L NPs. L NPs and Cs
showed a synergistic effect on the antioxidant response, while L NPs exhibited
effective antimicrobial activity.
Acid, alkali and toxic reagents such as acetone, dioxane are methanol are needed
in conventional lignin extraction methods. The harmful components produced during the extraction process limit the applications of lignin in the cosmetic, food and
medical industries. Shikinaka et al. (2018) introduced a simultaneous enzymatic
saccharification and comminution (SESC) method to isolate lignin fractions from
plants. The lignin fractions isolated by SESC are amorphous L NPs and can be utilized as a spin trap reagent and non-toxic ROS scavenger (Shikinaka et al. 2018).
The SESC L NPs never affected normal cells, they only acted on cancer and inflammation sites, so they are applicable in pharmaceutical preparations. As metal L NPs,
silver L NPs (Ag L NPs) have also been widely used in the drug delivery, medical
imaging and medical sensing. Lignin can form complexes with Ag cations to efficiently stabilize Ag L NPs. Marulasiddeshwara et al. (2017) reported an easy onepot green synthesis of lignin-capped Ag L NPs (LCSN). LCSN showed antimicrobial
activity against human pathogens such as S. aureus and Aspergillus niger, as well as
antioxidant activity. LCSN also inhibited adenosine diphosphate-induced platelet
aggregation without interfering with plasma coagulation. These functional properties and the non-toxic nature of LCSN facilitated its application in biomaterials for
tissue engineering and gene therapy.
5.5.4 Applications in Conductive Materials
Polyaniline (PANI) is a popular conductive polymer due to its good environmental
stability and low cost, but its application on an industrial scale has been restricted
due to its infusibility and insolubility, which make it very difficult to process
(Jaymand 2013). The introduction of substituent groups in their molecular structure
can decrease the rigidity of the PANI chains and, thus improving their processability
(Jaymand 2013). The preparation of ring-substituted PANI derivatives, such as
poly(o-methoxyaniline) (POMA) is a good example of how processability can be
improved by the addition of substituent groups. Wang et al. (2012) described the
synthesis of POMA-LS (POMA-LS) composites. The presence of LGS increased
the radical scavenging capacity, but decreased the alternating current conductivity
of the composites. The physical properties of the composites were determined by
the LS/POMA weight ratio. A higher LS/POMA weight ratio led to a higher specific
surface area and smaller POMA particles (Wang et al. 2012).
Z. Qin et al.
and 2) due to their small size, the L NPs enters intracellular space. Some lignin
monophenolic compounds, e.g. cinnamaldehyde, consumes adenosine triphosphate
(ATP) energy by infiltrating the bacteria and decreasing the intracellular pH. The
combination of these two mechanisms leads to cell death. Yang et al. (2018a) produced polyvinyl alcohol/Cs (PVA/Cs) hydrogels containing L NPs. L NPs and Cs
showed a synergistic effect on the antioxidant response, while L NPs exhibited
effective antimicrobial activity.
Acid, alkali and toxic reagents such as acetone, dioxane are methanol are needed
in conventional lignin extraction methods. The harmful components produced during the extraction process limit the applications of lignin in the cosmetic, food and
medical industries. Shikinaka et al. (2018) introduced a simultaneous enzymatic
saccharification and comminution (SESC) method to isolate lignin fractions from
plants. The lignin fractions isolated by SESC are amorphous L NPs and can be utilized as a spin trap reagent and non-toxic ROS scavenger (Shikinaka et al. 2018).
The SESC L NPs never affected normal cells, they only acted on cancer and inflammation sites, so they are applicable in pharmaceutical preparations. As metal L NPs,
silver L NPs (Ag L NPs) have also been widely used in the drug delivery, medical
imaging and medical sensing. Lignin can form complexes with Ag cations to efficiently stabilize Ag L NPs. Marulasiddeshwara et al. (2017) reported an easy onepot green synthesis of lignin-capped Ag L NPs (LCSN). LCSN showed antimicrobial
activity against human pathogens such as S. aureus and Aspergillus niger, as well as
antioxidant activity. LCSN also inhibited adenosine diphosphate-induced platelet
aggregation without interfering with plasma coagulation. These functional properties and the non-toxic nature of LCSN facilitated its application in biomaterials for
tissue engineering and gene therapy.
5.5.4 Applications in Conductive Materials
Polyaniline (PANI) is a popular conductive polymer due to its good environmental
stability and low cost, but its application on an industrial scale has been restricted
due to its infusibility and insolubility, which make it very difficult to process
(Jaymand 2013). The introduction of substituent groups in their molecular structure
can decrease the rigidity of the PANI chains and, thus improving their processability
(Jaymand 2013). The preparation of ring-substituted PANI derivatives, such as
poly(o-methoxyaniline) (POMA) is a good example of how processability can be
improved by the addition of substituent groups. Wang et al. (2012) described the
synthesis of POMA-LS (POMA-LS) composites. The presence of LGS increased
the radical scavenging capacity, but decreased the alternating current conductivity
of the composites. The physical properties of the composites were determined by
the LS/POMA weight ratio. A higher LS/POMA weight ratio led to a higher specific
surface area and smaller POMA particles (Wang et al. 2012).
Z. Qin et al.