Lignin is a byproduct
of agricultural industries and only has limited
applications. In this study, lignin was investigated for use in sustainable
biopolymeric packaging film. Alkali lignin (AL) and lignosulfonate
(LSS) were added to enzymatically modified soy protein isolate (SPI)
biopolymeric film with different concentrations with the goal of improvement
of film physical and functional properties. A radical scavenging activity
test revealed that films containing LSS had values 28 and 6% higher
than control and AL-based films, respectively; AL itself (not in films)
had significantly higher radical scavenging activity than LSS. This
indicates the activity of lignin is affected by interaction with SPI.
The higher compatibility between LSS and enzymatically modified SPI
resulted in a positive effect on surface smoothness, water absorption,
and mechanical properties of LSS-based films. Films containing AL
showed a high light absorption range in the UV region, and this UV-blocking
ability increased with increasing level of lignin. Deconvoluted Fourier
transform infrared spectra confirmed that the addition of lignin resulted
in some changes in the secondary structure of the protein matrix,
which were aligned with X-ray diffraction results. The addition of
lignin improved tensile strength (TS) and thermal stability of films
compared to the lignin-free control. This improvement in TS and thermal
stability was probably a result of new intermolecular interactions
between lignin and SPI. Water vapor permeability of the films containing
lignin decreased to 50% of the control because lignin played a role
as a filler in the matrix. On the basis of our observations, the incorporation
of lignin into biopolymeric film is capable of providing additional
benefits and solutions to various industries, such as food, packaging,
agriculture, and pharmaceuticals.
Cost-effective and sensitive aptasensor with guanine chemiluminescence detection capable of simply quantifying thrombin in human serum was developed using thrombin aptamer (TBA), one of the G-quadruplex DNA aptamers, without expensive nanoparticles and complicated procedures. Guanines of G-quadruplex TBA-conjugated carboxyfluorescein (6-FAM) bound with thrombin do not react with 3,4,5-trimethoxylphenylglyoxal (TMPG) in the presence of tetra-n-propylammonium hydroxide (TPA), whereas guanines of free TBA- and TBA-conjugated 6-FAM immobilized on the surface of graphene oxide rapidly react with TMPG to emit light. Thus, guanine chemiluminescence in 5% human serum with thrombin was lower than that without thrombin when TBA-conjugated 6-FAM was added in two samples and incubated for 20 min. In other words, the brightness of guanine chemiluminescence was quenched due to the formation of G-quadruplex TBA-conjugated 6-FAM bound with thrombin in a sample. High-energy intermediate, capable of emitting dim light by itself, formed from the reaction between guanines of TBA and TMPG in the presence of TPA, transfers energy to 6-FAM to emit bright light based on the principle of chemiluminescence energy transfer (CRET). G-quadruplex TBA aptasensor devised using the rapid interaction between TBA-conjugated 6-FAM and thrombin quantified trace levels of thrombin without complicated procedures. The limit of detection (LOD = background + 3 × standard deviation) of G-quadruplex TBA aptasensor with good linear calibration curve, accuracy, precision, and recovery was as low as 12.3 nM in 5% human serum. Using the technology reported in this research, we expect that various types of G-quadruplex DNA aptasensors capable of specifically sensing a target molecule such as ATP, HIV, ochratoxin, potassium ions, and thrombin can be developed.
The objective of this study was to investigate the effects of various solvents on the crystallinity and thermal expansion stability of PLA film. Three different PLA films were produced by the solvent casting technique; PLA in chloroform (PLA-C), PLA in methylene chloride (PLA-M), and PLA in methylene chloride: acetonitrile ¼ 50: 50 (PLA-MA). The PLA-MA had higher % crystallinity, 46.15, than the PLA-C, 24.03, and the PLA-M, 14.25. With this increase in crystallinity, the PLA-MA had improved thermal expansion stability as shown by very low accumulated dimensional changes at 20 to 100 C. Wide-angle X-ray diffraction identified multiple crystalline structures for the PLA-MA. Film barrier properties were also measured. PLA-MA had the lowest oxygen permeability. However, there was no significant difference in water vapor permeability among the three PLA films. The mechanical property tests revealed that the PLA-C and PLA-M were ductile while the PLA-MA was brittle in behavior. The PLA-MA was very hazy as compared with the PLA-C and PLA-M. This work has shown that the PLA-MA had increased % crystallinity and, more importantly, it had improved thermal expansion stability which can be very beneficial for the flexible packaging industry.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.