| 1. |
- Adolfsson, Karin H., et al.
(författare)
-
Scavenging of DPPH by Persistent Free Radicals in Carbonized Particles
- 2023
-
Ingår i: Advanced Sustainable Systems. - : Wiley. - 2366-7486. ; 7:3
-
Tidskriftsartikel (refereegranskat)abstract
- Persistent free radicals (PFR) in carbonized particles may play a role in degradation of environmental compounds. The influence of PFR is evaluated in various carbonized particles on their radical scavenging efficiency upon the common radical indicator 2-2-diphenyl-1-picrylhydrazyl (DPPH). Carbonized particles are derived by hydrothermal carbonization of glucose (C-W) or glucose and urea (NC-W) and ionothermal carbonization of glucose and urea ionic liquid (IL) (NC-IL). The carbonized materials contain OH/COOH, C=C, and C-O functionalities. The addition of urea introduces NH/NH2 functionalities. The content of polar surface groups is lower in IL-processed NC-IL. The scavenging ability, measured as DPPH UV–vis absorption decline, increases with concentration and time for all particles, while the efficiency changes are in the order of C-W > NC-W > NC-IL. Electron paramagnetic resonance analysis reveals similar radical concentration in all carbonized materials studied. The difference in efficiency is, thus, not directly related to the PFR concentration but rather to the type of PFR, surface functionalities and/or scavenging mechanism. According to the g-values, radicals in these particles are carbon-centered. The minor variation in g-values suggests interactions between the radicals and their environmental functional groups. This provides insights into the influence of PFR in carbonized materials on their radical scavenging efficiency.
|
|
| 2. |
- Aminlashgari, Nina, et al.
(författare)
-
Nanocomposites as novel surfaces for laser desorption ionization mass spectrometry
- 2011
-
Ingår i: Analytical Methods. - : Royal Society of Chemistry (RSC). - 1759-9660 .- 1759-9679. ; 3:1, s. 192-197
-
Tidskriftsartikel (refereegranskat)abstract
- The possibility to utilize nanocomposite films as easy-to-handle surfaces for surface assisted laser desorption ionization-mass spectrometry (SALDI-MS) of small molecules, such as pharmaceutical compounds, was evaluated. The signal-to-noise values of acebutolol, propranolol and carbamazepine obtained on the nanocomposite surfaces were higher than the values obtained on plain PLA surface showing that the nanoparticles participate in the ionization/desorption process even when they are immobilized in the polymer matrix. The advantages of nanocomposite films compared to the free nanoparticles used in earlier studies are the ease of handling and reduction of instrument contamination since the particles are immobilized into the polymer matrix. Eight inorganic nanoparticles, titanium dioxide, silicon dioxide, magnesium oxide, hydroxyapatite, montmorillonite nanoclay, halloysite nanoclay, silicon nitride and graphitized carbon black at different concentrations were solution casted to films with polylactide (PLA). There were large differences in signal intensities depending on the type of drug, type of nanoparticle and the concentration of nanoparticles. Polylactide with 10% titanium oxide or 10% silicon nitride functioned best as SALDI-MS surfaces. The limit of detection (LOD) for the study was ranging from 1.7 ppm up to 56.3 ppm and the signal to noise relative standard deviations for the surface containing 10% silicon nitride was approximately 20-30%. Scanning electron microscopy demonstrated in most cases a good distribution of the nanoparticles in the polymer matrix and contact angle measurements showed increasing hydrophobicity when the nanoparticle concentration was increased, which could influence the desorption and ionization. Overall, the results show that nanocomposite films have potential as surfaces for SALDI-MS analysis of small molecules.
|
|
| 3. |
- Aminlashgari, Nina, 1986-
(författare)
-
SALDI-MS Method Development for Analysis of Pharmaceuticals and Polymer Degradation Products
- 2012
-
Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Surface assisted laser desorption ionization-mass spectrometry (SALDI-MS) was evaluated as a new tool for analysis of polymer degradation products. A SALDI method was developed enabling rapid analysis of low molecular mass polyesters and their degradation products. In addition, the possibility to utilize nanocomposite films as easy-to-handle surfaces for analysis of pharmaceutical compounds was investigated. Poly(ε-caprolactone) was used as a model compound for SALDI-MS method development. The signal-to-noise values obtained by SALDI-MS were 20 times higher compared to traditional matrix assisted laser desorption ionization-mass spectrometry (MALDI-MS) of the same samples with 2,5-dihydroxybenzoic acid as a matrix. Halloysite nanoclay and magnesium oxide showed best potential as surfaces and clean backgrounds in the low mass range were observed. The SALDI-MS method for the analysis of polyester degradation products was also verified by electrospray ionization-mass spectrometry (ESI-MS). An advantage over ESI-MS is the possibility to directly analyze degradation products in buffer solutions. Compared to gas chromatography-mass spectrometry (GC-MS) it is possible to analyze polar compounds and larger molecular mass ranges at the same time as complicated extraction steps are avoided. The possibility to use nanocomposite films as surfaces instead of free nanoparticles was evaluated by solution casting of poly(lactide) (PLA) films with eight inorganic nanoparticles. The S/N values of the pharmaceutical compounds, acebutolol, propranolol and carbamazepine, analyzed on the nanocomposite surfaces were higher than the values obtained on the surface of plain PLA showing that the nanoparticles participated in the ionization/desorption process even when they are immobilized. Beside the ease of handling, the risk for instrument contamination is reduced when nanocomposites are used instead of free nanoparticles. The signal intensities depended on the type of drug, type and concentration of nanoparticle. PLA with 10 % titanium oxide or 10 % silicon nitride functioned best as SALDI-MS surfaces.
|
|
| 4. |
- Aminlashgari, Nina, et al.
(författare)
-
Surface Assisted Laser Desorption Ionization-Mass Spectrometry (SALDI-MS) for Analysis of Polyester Degradation Products
- 2012
-
Ingår i: Journal of the American Society for Mass Spectrometry. - : American Chemical Society (ACS). - 1044-0305 .- 1879-1123. ; 23:6, s. 1071-1076
-
Tidskriftsartikel (refereegranskat)abstract
- Novel surface assisted laser desorption ionization-mass spectrometry (SALDI-MS) method was developed for rapid analysis of low molecular mass polyesters and their degradation products by laser desorption ionization-mass spectrometry. Three polycaprolactone materials were analyzed by the developed method before and after hydrolytic degradation. The signal-to-noise values obtained by SALDI-MS were 20-100 times higher compared with the ones obtained by using traditional MALDI-MS matrices. A clean background at low mass range and higher resolution was obtained by SALDI-MS. Different nanoparticle, cationizing agent, and solvent combinations were evaluated. Halloysite nanoclay and magnesium hydroxide showed the best potential as SALDI surfaces. The SALDI-MS spectrum of the polyester hydrolysis products was verified by ESI-MS. The developed SALDI-MS method possesses several advantages over existing methods for similar analyses.
|
|
| 5. |
- Bianchi, F., et al.
(författare)
-
Novel sample-substrates for the determination of new psychoactive substances in oral fluid by desorption electrospray ionization-high resolution mass spectrometry
- 2019
-
Ingår i: Talanta. - : Elsevier B.V.. - 0039-9140 .- 1873-3573. ; 202, s. 136-144
-
Tidskriftsartikel (refereegranskat)abstract
- A reliable screening and non invasive method based on the use of microextraction by packed sorbent coupled with desorption electrospray ionization-high resolution mass spectrometry was developed and validated for the detection of new psychoactive substances in oral fluid. The role of different sample substrates in enhancing signal intensity and stability was evaluated by testing the performances of two polylactide-based materials, i.e. non-functionalized and functionalized with carbon nanoparticles, and a silica-based material compared to commercially available polytetrafluorethylene supports. The best results were achieved by using the non-functionalized polylactide substrates to efficiently ionize compounds in positive ionization mode, whereas the silica coating proved to be the best choice for operating in negative ionization mode. LLOQs in the low μg/L, a good precision with CV% always lower than 16% and RR% in the 83(±4)-120(±2)% range, proved the suitability of the developed method for the determination of the analytes in oral fluid. Finally, the method was applied for screening oral fluid samples for the presence of psychoactive substances during private parties, revealing mephedrone in only one sample out of 40 submitted to analysis.
|
|
| 6. |
- Feng, Zhaoxuan
(författare)
-
From Polysaccharides to Functional Materials for Trace Pharmaceutical Adsorption
- 2019
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The transition to bioeconomy will reduce our dependency on fossil fuels as well as contribute to a more sustainable society. Within this framework, exploitation and development of renewable substitutes to petroleum-based products provides feasible roadmap for the material design. Here a perspective is provided to how the natural polysaccharides chitosan (CS) and/or cellulose (CL) could be elaborated and transformed to high-performance materials with the explicit aim of removing trace pharmaceutical contaminants from the wastewater, thus facilitating the sustainable development. In the first part of the thesis, chitosan and cellulose were converted to the carbon spheres (C-sphere) through a microwave-assisted hydrothermal carbonization process, and C-sphere was further broken down to the nanographene oxide (nGO) via a simple oxidation route. On this foundation, a green pathway was developed for fabrication of biobased materials for wastewater purification. First, macroporous chitosan-based composite hydrogels with controllable properties were developed, where chitosan-derived nGO worked as a functional property enhancer. Second, a further development changing from the bulky hydrogels to microgels consisting of CS composite particles in the microscopic size was achieved by a fast one-pot spraying-drying process. The crosslinking reaction occurred in situ during the spray-drying. Last, the C-sphere by-itself was also believed to be a potential adsorbent for wastewater contaminants. In the next step the prepared systems were evaluated for their capacity to adsorb pharmaceutical contaminants. Diclofenac sodium (DCF) was utilized as the model drug, and the three fabricated bio-adsorbents all demonstrated effective DCF adsorption performance, with the adsorption efficiency varying from 65.6 to 100%. Moreover, the DCF adsorption kinetics, isotherms and thermodynamic study were also investigated to reveal the nature of the adsorption process with the different materials. Finally, chitosan-based microspheres were selected for the reusability study, with the adsorption efficiency above 70% retained after six adsorption-desorption cycles, thus further endowing the promising potential of the fabricated bio-adsorbents for commercial applications.
|
|
| 7. |
- Kalita, Naba Kumar, et al.
(författare)
-
Triggering Degradation of Cellulose Acetate by Embedded Enzymes : Accelerated Enzymatic Degradation and Biodegradation under Simulated Composting Conditions
- 2023
-
Ingår i: Biomacromolecules. - : American Chemical Society (ACS). - 1525-7797 .- 1526-4602. ; 24:7, s. 3290-3303
-
Tidskriftsartikel (refereegranskat)abstract
- A green strategy that significantly accelerates the biodegradation rate of cellulose acetate (CA) by triggering deacetylation was demonstrated. Lipase isolated from Candida rugosa was immobilized on CA particles (immobilized lipase (IL)) by a physical entrapment method and further incorporated in CA films. After 40 days of aging in contact with external enzymes (lipase and cellulase), the number-average molecular weight (Mn) of CA/IL 5% decreased by 88%, while the Mn of CA only exhibited a 48% reduction. Fourier transform infrared and nuclear magnetic resonance spectroscopy of CA/IL 5% indicated significant deacetylation, which was further supported by the decrease of the water contact angle from 59 to 16°. These drastic changes were not observed for CA. Similar differences in the degradation rate were observed during aging under simulated composting conditions. After 180 days of simulated composting, traces of CA/IL 5% were barely observable, while large pieces of CA still remained. This could open the door to modified lignocellulose materials with retained biodegradability, also reducing the requirements for the degradation environment as the process is initiated from inside of the material.
|
|
| 8. |
- Yadav, Nisha, et al.
(författare)
-
Carbon Dot-Triggered Photocatalytic Degradation of Cellulose Acetate
- 2021
-
Ingår i: Biomacromolecules. - : American Chemical Society (ACS). - 1525-7797 .- 1526-4602. ; 22:5, s. 2211-2223
-
Tidskriftsartikel (refereegranskat)abstract
- Chemical modification of biopolymers, before use in thermo-plastic applications, can reduce the susceptibility to open environment degradation. We demonstrate carbon dots (CDs) as green photocatalytic triggers that can render the common cellulose derivative, cellulose acetate (CA), degradable under open environment relevant conditions. CD-modified cellulose acetate (CA + CD) films were subjected to UV-A irradiation in air and simulated sea water, and the degradation process was mapped by multiple spectroscopic, chromatographic, and microscopy techniques. The addition of CDs effectively catalyzed the deacetylation reaction, the bottleneck preventing biodegradation of CA. The photocatalytically activated degradation process led to significant weight loss, release of small molecules, and regeneration of cellulose fibers. The weight loss of CA + CD after 30 days of UV-A irradiation in air or simulated sea water was 53 and 43%, respectively, while the corresponding values for plain CA films were 12 and 4%. At the same time the weight average molar mass of CA + CD decreased from 62,000 to 11,000 g/mol and 15,000 g/mol during UV-A irradiation in air and simulated sea water, respectively, and the degree of substitution (DS) decreased from 2.2 to 1.6 both in air and in water. The aging in water alone did not affect the weight average molar mass, but the DS was decreased to 1.9. Control experiments confirmed the generation of hydrogen peroxide when aqueous CD dispersion was subjected to UV-A irradiation, indicating a free radical mechanism. These results are promising for the development of products, such as mulching films, with photocatalytically triggered environmental degradation processes.
|
|
| 9. |
- Magnusson, Mikael, et al.
(författare)
-
Bioconversion of food waste to biocompatible wet-laid fungal films
- 2022
-
Ingår i: Materials & design. - : Elsevier. - 0264-1275 .- 1873-4197. ; 216
-
Tidskriftsartikel (refereegranskat)abstract
- The fungus Rhizopus delemar was grown on bread waste in a submerged cultivation process and wet-laid into films. Alkali or enzyme treatments were used to isolate the fungal cell wall. A heat treatment was also applied to deactivate biological activity of the fungus. Homogenization of fungal biomass was done by an iterative ultrafine grinding process. Finally, the biomass was cast into films by a wet-laid process. Ultrafine grinding resulted in densification of the films. Fungal films showed tensile strengths of up to 18.1 MPa, a Young's modulus of 2.3 GPa and a strain at break of 1.4%. Highest tensile strength was achieved using alkali treatment, with SEM analysis showing a dense and highly organized structure. In contrast, less organized structures were obtained using enzymatic or heat treatments. A cell viability assay and fluorescent staining confirmed the biocompatibility of the films. A promising route for food waste valorization to sustainable fungal wet-laid films was established. © 2022 The Authors
|
|
| 10. |
- Tardy, Blaise L., et al.
(författare)
-
Prospects for the integration of lignin materials into the circular economy
- 2023
-
Ingår i: Materials Today. - : Elsevier BV. - 1369-7021 .- 1873-4103. ; 65, s. 122-132
-
Tidskriftsartikel (refereegranskat)abstract
- Lignin is a remarkable natural polyphenol that provides trees with physical and (bio-)chemical resistance, as well as the ability to reach considerable heights. Lignin is also intrinsically circular with slow biodegradability, thereby serving as a carbon source for soils. There is a growing interest in using industrial lignin as an environmentally and economically beneficial material. However, most of the industrially produced lignin is still used as a cost-efficient energy source by the forestry sector. To efficiently redirect the use towards material applications and to avoid the end-of-life problems connected to traditional plastics, there is an imminent need and opportunity to include circularity as an important design parameter. In this review, we critically assess opportunities and obstacles for lignin as a component in circular materials, as guided by life cycle assessment and benchmarking to best practices in materials science and engineering, e.g., circularity "by design". We cover and reflect on recent and emerging advances in nanotechnology and materials science that showcase how lignin can contribute to carbon fixation as a viable alternative to its combustion in the pulping processes. We argue that, with adequate considerations, lignin has the potential to enable the development of new circular biobased materials that do not cause accumulation of environmentally persistent waste, and are equipped with attractive functionalities and performance for the benefit of a sustainable society.
|
|
