Search Results (45)

The valorization of agroindustrial residues represents a sustainable alternative in the production of materials attractive for sustainable technologies. In this work, cellulosic materials were isolated from treated pea pods aiming to obtain highly crystalline, thermally stable reinforcements for biocomposites. Four different treatments were evaluated; two employed 0.5 or 0.75 M oxalic acid (OA) solutions at 90 °C, and two used 5% w/v KOH solutions after each OA treatment. The cellulosic materials (10, 20 wt.%) were compounded with a polylactic acid (PLA) matrix and polyvinyl alcohol (0, 2.5 wt.%) as a compatibilizer by extrusion. Compression molding was used to obtain samples to study the composite’s mechanical and thermal behavior. The cellulosic materials and the composites were characterized by Fourier transform infrared spectroscopy, thermogravimetry, and calorimetry. The composites were also subjected to flexural, thermo-mechanical, and water absorption testing. The cellulosic reinforcements obtained using 0.75 M OA and 0.5 M OA and KOH showed the highest crystallinities (91–92%). In general, 20 wt.% reinforced composites showed lower thermal expansion and higher water absorption than those incorporating 10 wt.% reinforcements. The composites incorporating 10 wt.% of 0.5 M OA treated pea pods exhibited flexural modulus/strength 17/3% higher than that of PLA. The composites incorporating 20 wt.% of 0.5 M OA and KOH-treated pea pods showed the highest flexural modulus/strength, 35/25% higher than that of PLA. These results show that agroresidues treated with low-concentration organic acids can be effectively used to tune the mechanical, thermal, and water absorption behavior of biodegradable composites. Full article

The photochemistry of 1,3,4-oxadiazoles remains poorly understood, despite their recognized importance in medicinal chemistry and materials science. In this work, we report a detailed matrix-isolation study of 2-amino-5-(4-methoxyphenyl)-1,3,4-oxadiazole, combining low-temperature infrared spectroscopy with broadband UV photolysis and quantum chemical calculations. Theoretical analysis predicts the gas-phase molecule to exist exclusively as the amino tautomer, populating two nearly isoenergetic conformers (anti and syn) defined by the relative orientation of the amino and methoxy groups. Experimental IR spectra of the compound isolated in Ar and Xe matrices at 15 K confirm sole trapping of the amino tautomer. Annealing of the Xe matrix to the highest achievable temperature induced no detectable spectral changes, consistent with the predicted isoenergetic character of the conformers. Upon broadband UV irradiation (λ > 200 nm), the compound undergoes ring opening through N−N and C−O bond cleavages, paralleling the behavior of unsubstituted 1,3,4-oxadiazole system. Isocyanates emerge as the predominant photoproducts from these photochemical pathways. Additionally, spectroscopic evidence supports an alternative reaction pathway involving early-stage amino−imino tautomerization, followed by ring-opening of the imino tautomer through isocyanic acid extrusion, leading to the formation of a nitrilimine intermediate. This reactive species subsequently photorearranges into a carbodiimide via a diazirine-mediated pathway. All photoproducts were unambiguously identified through their distinct IR signatures, supported by quantum chemical calculations and reference data from structurally related systems. These findings provide unprecedented insight into the photochemical behavior of substituted 1,3,4-oxadiazoles and unveil new reaction pathways modulated by substituent effects, expanding the understanding of their photoreactivity. Full article

Amid growing global concerns about environmental sustainability and food security, plant-based meat substitutes have emerged as a promising alternative to conventional meat. However, current formulations, especially those based on soy protein isolate (SPI) often fail to replicate the desired texture and structural integrity. To address this limitation, this study aimed to evaluate the use of whole yeast powder (WYP) combined with SPI for producing plant-based meat analogues via high-moisture extrusion. Seven groups were designed: a control group with 0% WYP, five treatment groups with 5%, 10%, 20%, 30%, and 40% WYP, and one reference group containing 20% yeast protein powder (YPP). Although lower in protein content than yeast protein powder (YPP), whole yeast powder exhibits superior water-binding capacity and network-forming ability owing to its complex matrix and fiber content. At a 20% inclusion level, whole yeast powder demonstrated a higher fibrous degree (1.84 ± 0.02 vs. 1.81 ± 0.04), greater hardness (574.93 ± 5.84 N vs. 531.18 ± 17.34 N), and increased disulfide bonding (95.33 ± 0.92 mg/mL vs. 78.41 ± 0.78 mg/mL) compared to 20% YPP. Scanning electron microscopy (SEM) and low-field nuclear magnetic resonance (LF-NMR) revealed that whole yeast powder facilitated the formation of aligned fibrous networks and enhanced water binding. Fourier transform infrared spectroscopy (FTIR) confirmed an increase in β-sheet content (0.267 ± 0.003 vs. 0.260 ± 0.003), which contributed to improved protein aggregation. Increasing the WYP content to 30–40% led to a decline in these parameters, including a reduced fibrous degree (1.69 ± 0.06 at 40% WYP) and weakened molecular interactions (p < 0.05). The findings highlight 20% WYP as the optimal substitution level, offering superior textural enhancement and fibrous structure formation compared to YPP. These results suggest that WYP is not only a cost-effective and processing-friendly alternative to YPP but also holds great promise for scalable industrial application in the plant-based meat sector. Its compatibility with extrusion processes and ability to improve sensory and structural attributes supports its relevance for sustainable meat analogue production. Full article

Ethylene and sulfur dioxide molecules were co-deposited on a CsI window at cryogenic temperature, and the photoproducts upon UV irradiation were observed using Fourier transform infrared (FTIR) spectroscopy. The products were found to be UV wavelength-dependent; at shorter wavelengths (λ = 266 nm) one strong peak was observed while more than three peaks were identified at longer UV wavelengths (λ = 300 nm). Spectral features changed seamlessly along with UV wavelength. Density functional theory (DFT) calculations were carried out for potential products, and spectral matches between observations and calculations seemed satisfactory, assuming a cyclic molecule (oxathietane 2-oxide) as the main photoproduct at longer UV wavelengths. On the other hand, the spectra of photoproducts at shorter UV wavelengths were reproduced by assuming the decomposition products of an intermediate, from the supplementary experiments using deuterated samples. Plausible photoreaction schemes were presented to account for the observed photoproducts. Full article

Ethyl maltol was investigated using matrix isolation infrared spectroscopy and DFT calculations. In an argon matrix (14.5 K), the compound was found to exist in a single conformer (form I), characterized by an intramolecular hydrogen bond with an estimated energy of ~17 kJ mol⁻¹. The IR spectrum of this conformer was assigned, and the molecule’s potential energy landscape was explored to understand the relative stability and isomerization dynamics of the conformers. Upon annealing the matrix to 41.5 K, ethyl maltol was found to predominantly aggregate into a centrosymmetric dimer (2× conformer I) bearing two intermolecular hydrogen bonds with an estimated energy of ca. 28 kJ mol⁻¹ (per bond). The UV-induced (λ > 235 nm) photochemistry of the matrix-isolated ethyl maltol was also investigated. After 1 min of irradiation, band markers of two rearrangement photoproducts formed through the photoinduced detachment-attachment (PIDA) mechanism, in which the ethyl maltol radical acts as an intermediate, were observed: 1-ethyl-3-hydroxy-6-oxibicyclo [3.1.0] hex-3-en-2-one and 2-ethyl-2H-pyran-3,4-dione. The first undergoes subsequent reactions, rearranging to 4-hydroxy-4-propanoylcyclobut-2-en-1-one and photofragmenting to cyclopropenone and 2-hydroxybut-1-en-1-one. Other final products were also observed, specifically acetylene and CO (the expected fragmentation products of cyclopropenone), and CO₂. Overall, the study demonstrated ethyl maltol’s high reactivity under UV irradiation, with significant photochemical conversion occurring within minutes. The rapid photochemical conversion, with complete consumption of the compound in 20 min, should be taken into account in designing practical applications of ethyl maltol. Full article

Reactions of bis(benzene)chromium (Bz₂Cr) and ozone (O₃) were studied using low-temperature argon matrix-isolation infrared spectroscopy with supporting DFT calculations. When Bz₂Cr and O₃ were co-deposited, they reacted upon matrix deposition to produce two new prominent peaks in the infrared spectrum at $431 {\mathrm{c}\mathrm{m}}^{-1}$ and $792 {\mathrm{c}\mathrm{m}}^{-1}$. These peaks increased upon annealing the matrix to 35 K and decreased upon UV irradiation at λ = 254 nm. The oxygen-18 and mixed oxygen-16,18 isotopic shift pattern of the peak at $792 {\mathrm{c}\mathrm{m}}^{-1}$ is consistent with the antisymmetric stretch of a symmetric ozonide species. DFT calculations of many possible ozonide products of this reaction were made. The formation of a hydrogen ozonide (H₂O₃) best fits the original peaks and the oxygen-18 isotope shift pattern. Energy considerations lead to the conclusion that the chromium-containing product of this reaction is the coupled product benzene-chromium-biphenyl-chromium-benzene (BzCrBPCrBz). $2{\mathrm{B}\mathrm{z}}_2\mathrm{C}\mathrm{r}+{\mathrm{O}}_3\to {\mathrm{H}}_2{\mathrm{O}}_3+\mathrm{B}\mathrm{z}\mathrm{C}\mathrm{r}\mathrm{B}\mathrm{P}\mathrm{C}\mathrm{r}\mathrm{B}\mathrm{z}, {∆E}_{calc}=-52.13\mathrm{k}\mathrm{c}\mathrm{a}\mathrm{l}/\mathrm{m}\mathrm{o}\mathrm{l}$. Full article

Whey protein isolate (WPI) hydrogels are attractive biomaterials for application in bone repair and regeneration. However, their main limitation is low mechanical strength. Therefore, to improve these properties, the incorporation of ceramic phases into hydrogel matrices is currently being performed. In this study, novel whey protein isolate/calcium silicate (WPI/CaSiO₃) hydrogel biomaterials were prepared with varying concentrations of a ceramic phase (CaSiO₃). The aim of this study was to investigate the effect of the introduction of CaSiO₃ to a WPI hydrogel matrix on its physicochemical, mechanical, and biological properties. Our Fourier Transform Infrared Spectroscopy results showed that CaSiO₃ was successfully incorporated into the WPI hydrogel matrix to create composite biomaterials. Swelling tests indicated that the addition of 5% (w/v) CaSiO₃ caused greater swelling compared to biomaterials without CaSiO₃ and ultimate compressive strength and strain at break. Cell culture experiments demonstrated that WPI hydrogel biomaterials enriched with CaSiO₃ demonstrated superior cytocompatibility in vitro compared to the control hydrogel biomaterials without CaSiO₃. Thus, this study revealed that the addition of CaSiO₃ to WPI-based hydrogel biomaterials renders them more promising for bone tissue engineering applications. Full article

The reactive open-shell species play a very important role in the radiation-induced molecular evolution occurring in the cold areas of space and presumably leading to the formation of biologically relevant molecules. This review presents an insight into the mechanism of such processes coming from matrix isolation studies with a main focus on the experimental and theoretical studies performed in the author’s laboratory during the past decade. The radicals and radical cations produced from astrochemically relevant molecules were characterized by Fourier transform infrared (FTIR) and electron paramagnetic resonance (EPR) spectroscopy. Small organic radicals containing C, O, and N atoms are considered in view of their possible role in the formation of complex organic molecules (COMs) in space, and a comparison with earlier results is given. In addition, the radical–molecule complexes generated from isolated intermolecular complexes in matrices are discussed in connection with their model significance as the building blocks for COMs formed under the conditions of extremely restricted molecular mobility at cryogenic temperatures. Full article

New scaffolds, based on whey protein isolate (WPI) and chitosan (CS), have been proposed and investigated as possible materials for use in osteochondral tissue repair. Two types of WPI-based hydrogels modified by CS were prepared: CS powder was incorporated into WPI in either dissolved or suspended powder form. The optimal chemical composition of the resulting WPI/CS hydrogels was chosen based on the morphology, structural properties, chemical stability, swelling ratio, wettability, mechanical properties, bioactivity, and cytotoxicity evaluation. The hydrogels with CS incorporated in powder form exhibited superior mechanical properties and higher porosity, whereas those with CS incorporated after dissolution showed enhanced wettability, which decreased with increasing CS content. The introduction of CS powder into the WPI matrix promoted apatite formation, as confirmed by energy dispersive spectroscopy (EDS) and Fourier transform infrared spectroscopy (FTIR) analyses. In vitro cytotoxicity results confirmed the cytocompatibility of CS powder modified WPI hydrogels, suggesting their suitability as cell scaffolds. These findings demonstrate the promising potential of WPI/CS scaffolds for osteochondral tissue repair. Full article

New water-soluble nanocomposites with cobalt oxide nanoparticles (Co₃O₄NPs) in a poly(1-vinyl-1,2,4-triazole) (PVT) matrix have been synthesized. The PVT used as a stabilizing polymer matrix was obtained by radical polymerization of 1-vinyl-1,2,4-triazole (VT). The polymer nanocomposites with Co₃O₄ nanoparticles were characterized by ultraviolet–visible, Fourier-transform infrared spectroscopy, atomic absorption spectroscopy, transmission electron microscopy, dynamic light scattering, gel permeation chromatography, and simultaneous thermogravimetric analysis. The resulting polymer nanocomposites consist of spherical isolated cobalt nanoparticles with a diameter of 1 to 13 nm. The average hydrodynamic diameters of macromolecular coils are 15–112 nm. The cobalt content in nanocomposites ranges from 1.5 to 11.0 wt.%. The thermal stability of nanocomposites is up to 320 °C. Full article

Recent joint mass spectrometric and IR photodissociation studies have provided proof on the existence of octa-coordinated ionic lanthanide-carbonyl complexes under those extreme gaseous conditions. In contrast, in older literature concerning cryogenic studies of neutral Ln(CO)_x species, the highest coordination was assigned to hexa-coordinated Ln(CO)₆ molecules. The present study aims to clarify the above controversy using matrix isolation spectroscopy and DFT calculations. In order to ensure the maximum possible coordination, the Ln(CO)_x complexes were synthesized in neat CO cryogenic matrices at 10 K and were investigated by infrared and UV-visible spectroscopy. The formed complexes were identified on the basis of the characteristic CO stretching frequencies of the ground-state molecules predicted by DFT calculations. Our joint experimental–theoretical analysis confirmed the preference of octa-coordinated Ln(CO)₈ complexes in cryogenic neat CO matrices. Full article

Targeted synthesis of C/composite Ni-based material was carried out by the method of matrix isolation. The composite was formed with regard to the features of the reaction of catalytic decomposition of methane. The morphology and physicochemical properties of these materials have been characterized using a number of methods: elemental analysis, scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, temperature programmed reduction (TPR-H₂), specific surface areas (SSA), thermogravimetric analysis, and differential scanning calorimetry (TGA/DSC). It was shown by FTIR spectroscopy that nickel ions are immobilized on the polymer molecule of polyvinyl alcohol, and during heat treatment, polycondensation sites are formed on the surface of the polymer molecule. By the method of Raman spectroscopy, it was shown that already at a temperature of 250 °C, a developed conjugation system with sp2-hybridized carbon atoms begins to form. The SSA method shows that the formation of the composite material resulted in a matrix with a developed specific surface area of 20 to 214 m²/g. The XRD method shows that nanoparticles are essentially characterized by Ni, NiO reflexes. The composite material was established by microscopy methods to be a layered structure with uniformly distributed nickel-containing particles 5–10 nm in size. The XPS method determined that metallic nickel was present on the surface of the material. A high specific activity was found in the process of catalytic decomposition of methane—from 0.9 to 1.4 g_H2/g_cat/h, X_CH4, from 33 to 45% at a reaction temperature of 750 °C without the stage of catalyst preliminary activation. During the reaction, the formation of multi-walled carbon nanotubes occurs. Full article

N–acetyl–L–cysteine (NAC), a derivative of the L–cysteine amino acid, presents antioxidant and mucolytic properties of pharmaceutical interest. This work reports the preparation of organic-inorganic nanophases aiming for the development of drug delivery systems based on NAC intercalation into layered double hydroxides (LDH) of zinc–aluminum (Zn₂Al–NAC) and magnesium–aluminum (Mg₂Al–NAC) compositions. A detailed characterization of the synthesized hybrid materials was performed, including X-ray diffraction (XRD) and pair distribution function (PDF) analysis, infrared and Raman spectroscopies, solid-state ¹³carbon and ²⁷aluminum nuclear magnetic resonance (NMR), simultaneous thermogravimetric and differential scanning calorimetry coupled to mass spectrometry (TG/DSC–MS), scanning electron microscopy (SEM), and elemental chemical analysis to assess both chemical composition and structure of the samples. The experimental conditions allowed to isolate Zn₂Al–NAC nanomaterial with good crystallinity and a loading capacity of 27.3 (m/m)%. On the other hand, NAC intercalation was not successful into Mg₂Al–LDH, being oxidized instead. In vitro drug delivery kinetic studies were performed using cylindrical tablets of Zn₂Al–NAC in a simulated physiological solution (extracellular matrix) to investigate the release profile. After 96 h, the tablet was analyzed by micro-Raman spectroscopy. NAC was replaced by anions such as hydrogen phosphate by a slow diffusion-controlled ion exchange process. Zn₂Al–NAC fulfil basic requirements to be employed as a drug delivery system with a defined microscopic structure, appreciable loading capacity, and allowing a controlled release of NAC. Full article

The dynamic development of nanotechnology has enabled the development of innovative and novel techniques for the production and use of nanomaterials. One of them is the use of nanocapsules based on biodegradable biopolymer composites. Closing compounds with antimicrobial activity inside the nanocapsule cause the gradual release of biologically active substances into the environment, and the effect on pathogens is regular, prolonged and targeted. Known and used in medicine for years, propolis, thanks to the synergistic effect of active ingredients, has antimicrobial, anti-inflammatory and antiseptic properties. Biodegradable and flexible biofilms were obtained, the morphology of the composite was determined using scanning electron microscopy (SEM) and particle size was measured by the dynamic light scattering (DLS) method. Antimicrobial properties of biofoils were examined on commensal skin bacteria and pathogenic Candida isolates based on the growth inhibition zones. The research confirmed the presence of spherical nanocapsules with sizes in the nano/micrometric scale. The properties of the composites were characterized by infrared (IR) and ultraviolet (UV) spectroscopy. It has been proven that hyaluronic acid is a suitable matrix for the preparation of nanocapsules, as no significant interactions between hyaluronan and the tested compounds have been demonstrated. Color analysis and thermal properties, as well as the thickness and mechanical properties of the obtained films, were determined. Antimicrobial properties of the obtained nanocomposites were strong in relation to all analyzed bacterial and yeast strains isolated from various regions of the human body. These results suggest high potential applicability of the tested biofilms as effective materials for dressings to be applied on infected wounds. Full article

Biofilms represent the main mode of existence of bacteria and play very significant roles in many industrial, medical and agricultural fields. Analysis of biofilms is a challenging task owing to their sophisticated composition, heterogeneity and variability. In this study, biofilms formed by the rhizobacterium Azospirillum baldaniorum (strain Sp245), isolated biofilm matrix and its macrocomponents have for the first time been studied in detail, using Fourier transform infrared (FTIR) spectroscopy, with a special emphasis on the methodology. The accompanying novel data of comparative chemical analyses of the biofilm matrix, its fractions and lipopolysaccharide isolated from the outer membrane of the cells of this strain, as well as their electrophoretic analyses (SDS-PAGE) have been found to be in good agreement with the FTIR spectroscopic results. Full article