Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 5.418
Filtrar
1.
Protein Sci ; 33(6): e5022, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38747440

RESUMO

Differential scanning fluorimetry (DSF) is a method to determine the apparent melting temperature (Tma) of a purified protein. In DSF, the raw unfolding curves from which Tma is calculated vary widely in shape and complexity. However, the tools available for calculating Tma are only compatible with the simplest of DSF curves, hindering many otherwise straightforward applications of the technology. To overcome this limitation, we designed new mathematical models for Tma calculation that accommodate common forms of variation in DSF curves, including the number of transitions, the presence of high initial signal, and temperature-dependent signal decay. When tested these models against DSFbase, an open-source database of 6235 raw, real-life DSF curves, these models outperformed the existing standard approaches of sigmoid fitting and maximum of the first derivative. To make these models accessible, we created an open-source software and website, DSFworld (https://gestwickilab.shinyapps.io/dsfworld/). In addition to these improved fitting capabilities, DSFworld also includes features that overcome the practical limitations of many analysis workflows, including automatic reformatting of raw data exported from common qPCR instruments, labeling of data based on experimental variables, and flexible interactive plotting. We hope that DSFworld will enable more streamlined and accurate calculation of Tma values for DSF experiments.


Assuntos
Fluorometria , Software , Fluorometria/métodos , Temperatura de Transição , Proteínas/química
2.
Sci Rep ; 14(1): 11055, 2024 05 14.
Artigo em Inglês | MEDLINE | ID: mdl-38745038

RESUMO

Identifying pathogenic microorganisms as early as possible is critical for selecting the appropriate antimicrobial therapy in infected patients. We previously reported the development of the Tm mapping method for identifying a broad range of pathogenic bacteria within 3 h of blood collection. However, the Tm mapping identification requires an analytical instrument with a tube-to-tube variation of no more than 0.1 °C, so we can only use a few instruments that have such high thermal accuracy. To address the problem, we developed the improved Tm mapping method using imperfect-match linear long quenching probes (IMLL Q-probes). Using IMLL Q-probes, almost all commercially available analytical instruments can be used for the Tm mapping method. Some bacterial species cannot be narrowed down to one species, but they can at least be narrowed down to the genus level. The Tm mapping method using IMLL Q-probes is useful for deciding on antimicrobial therapy in infected patients.


Assuntos
Bactérias , Humanos , Bactérias/isolamento & purificação , Temperatura de Transição
3.
AAPS PharmSciTech ; 25(5): 103, 2024 May 07.
Artigo em Inglês | MEDLINE | ID: mdl-38714634

RESUMO

Crystallization of amorphous pharmaceutical solids are widely reported to be affected by the addition of polymer, while the underlying mechanism require deep study. Herein, crystal growth behaviors of glassy griseofulvin (GSF) doped with various 1% w/w polymer were systematically studied. From the molecular structure, GSF cannot form the hydrogen bonding interactions with the selected polymer poly(vinyl acetate), polyvinyl pyrrolidone (PVP), 60:40 vinyl pyrrolidone-vinyl acetate copolymer (PVP/VA 64), and poly(ethylene oxide) (PEO). 1% w/w polymer exhibited weak or no detectable effects on the glass transition temperature (Tg) of GSF. However, crystal growth rates of GSF was altered from 4.27-fold increase to 2.57-fold decrease at 8 ℃ below Tg of GSF. Interestingly, the ability to accelerate and inhibit the growth rates of GSF crystals correlated well with Tg of polymer, indicating the controlling role of segmental mobility of polymer. Moreover, ring-banded growth of GSF was observed in the polymer-doped systems. Normal compact bulk and ring-banded crystals of GSF were both characterized as the thermodynamically stable form I. More importantly, formation of ring-banded crystals of GSF can significantly weaken the inhibitory effects of polymer on the crystallization of glassy GSF.


Assuntos
Cristalização , Griseofulvina , Polímeros , Temperatura de Transição , Griseofulvina/química , Cristalização/métodos , Polímeros/química , Estabilidade de Medicamentos , Ligação de Hidrogênio , Polivinil/química , Polietilenoglicóis/química , Povidona/química , Vidro/química
4.
Int J Pharm ; 656: 124088, 2024 May 10.
Artigo em Inglês | MEDLINE | ID: mdl-38582102

RESUMO

Viscosupplementation consists of hyaluronic acid (HA) intra-articular injections, commonly applied for osteoarthritis treatment while non-steroidal anti-inflammatory drugs (NSAIDs) are widely administered for pain relief. Here, HA and a NSAID (celecoxib) were combined in a formulation based on a low transition temperature mixture (LTTM) of glycerol:sorbitol, reported to increase celecoxib's solubility, thus rendering a potential alternative viscosupplement envisioning enhanced therapeutic efficiency. The inclusion of glucosamine, a cartilage precursor, was also studied. The developed formulations were assessed in terms of rheological properties, crucial for viscosupplementation: the parameters of crossover frequency, storage (G') and loss (G'') moduli, zero-shear-rate viscosity, stable viscosity across temperatures, and shear thinning behaviour, support viscoelastic properties suitable for viscosupplementation. Additionally, the gels biocompatibility was confirmed in chondrogenic cells (ATDC5). Regarding drug release studies, high and low clearance scenarios demonstrated an increased celecoxib (CEX) release from the gel (6 to 73-fold), compared to dissolution in PBS. The low clearance setup presented the highest and most sustained CEX release, highlighting the importance of the gel structure in CEX delivery. NMR stability studies over time demonstrated the LTTM+HA+CEX (GHA+CEX) gel as viable candidate for further in vivo evaluation. In sum, the features of GHA+CEX support its potential use as alternative viscosupplement.


Assuntos
Anti-Inflamatórios não Esteroides , Celecoxib , Liberação Controlada de Fármacos , Ácido Hialurônico , Osteoartrite , Viscossuplementação , Celecoxib/administração & dosagem , Celecoxib/química , Ácido Hialurônico/química , Ácido Hialurônico/administração & dosagem , Osteoartrite/tratamento farmacológico , Viscossuplementação/métodos , Anti-Inflamatórios não Esteroides/administração & dosagem , Anti-Inflamatórios não Esteroides/química , Viscosidade , Temperatura de Transição , Reologia , Animais , Linhagem Celular , Camundongos , Solubilidade , Glicerol/química , Glucosamina/química , Glucosamina/administração & dosagem , Viscossuplementos/administração & dosagem , Viscossuplementos/química , Injeções Intra-Articulares
5.
Eur J Pharm Biopharm ; 198: 114274, 2024 May.
Artigo em Inglês | MEDLINE | ID: mdl-38561067

RESUMO

Amorphous solid dispersions (ASDs) using proteins as carriers have emerged as a promising strategy for stabilizing amorphous drug molecules. Proteins possess diverse three-dimensional structures that significantly influence their own properties and may also impact the properties of ASDs. We prepared ß-lactoglobulin (BLG) with different contents of ß-sheet and α-helical secondary structures by initially dissolving BLG in different mixed solvents, containing different ratios of water, methanol/ethanol, and acetic acid, followed by spray drying of the solutions. Our findings revealed that an increase in α-helical content resulted in a decrease in the glass transition temperature (Tg) of the protein. Subsequently, we utilized the corresponding mixed solvents to dissolve both BLG and the model drug celecoxib (CEL), allowing the preparation of ASDs containing either ß-sheet-rich or α-helix/random coil-rich BLG. Using spray drying, we successfully developed BLG-based ASDs with drug loadings ranging from 10 wt% to 90 wt%. At drug loadings below 40 wt%, samples prepared using both methods exhibited single-phase ASDs. However, heterogeneous systems formed when the drug loading exceeded 40 wt%. At higher drug loadings, physical stability assessments demonstrated that the α-helix/random coil-rich BLG structure exerted a more pronounced stabilizing effect on the drug-rich phase compared to the ß-sheet-rich BLG. Overall, our results highlight the importance of considering protein secondary structure in the design of ASDs.


Assuntos
Água , Temperatura de Transição , Celecoxib/química , Temperatura , Solventes , Solubilidade , Composição de Medicamentos/métodos
6.
Food Chem ; 447: 138980, 2024 Jul 30.
Artigo em Inglês | MEDLINE | ID: mdl-38564849

RESUMO

Supercooling is a main controllable factor for the fundamental understanding the high-pressure shift freezing (HPSF). In the study, a self-developed device based on the diamond anvil cell (DAC) and confocal Raman microscopy was utilized to realize an in-situ investigation of supercooling behaviour during HPSF of the pure water and sucrose solution. The spectra were used to determine the freezing point which is shown as a spectral phase marker (SD). The hydrogen bond strengths of water and sucrose solution under supercooling states were estimated by peak position and peak area ratio of sub-peaks. The results showed that the OH stretching bands had redshift under supercooling states. Moreover, the addition of sucrose molecules could strengthen the hydrogen bonding strength of water molecules under supercooling states. Thus, the DAC combined with Raman spectroscopy could be considered a novel strategy for a deep understanding of the supercooling behaviour during HPSF.


Assuntos
Água , Congelamento , Água/química , Temperatura de Transição , Microscopia Confocal , Ligação de Hidrogênio
7.
Acta Parasitol ; 69(1): 889-897, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-38470530

RESUMO

PURPOSE: Strongyloides stercoralis is a parasite with special characteristics presenting it as a unique nematode. Iran is an endemic area for S. stercoralis. In this study, nested-qPCR-high resolution melting (HRM) technology was applied on some human isolates of S. stercoralis from this country by focusing on evolutionary genetics analysis. METHODS: Twelve human isolates of S. stercoralis were collected from four endemic provinces of Iran. Genomic DNA was extracted from a single filariform larva for every isolate. Using specific primers targeting partial regions in cox1 gene, nested-qPCR-HRM was performed and melting-curve profiles were analyzed alongside the evaluation of genetic proximity and phylogenetic analysis using MEGA7 and DnaSP5 software. RESULTS: The melting temperature (Tm) values of the isolates were 77.9 °C-78.3 °C. All isolates from Guilan, Mazandaran, and Khouzestan Provinces shared Tm values of 78.2 °C to 78.3 °C, while the isolates from Hormozgan Province showed Tm values of 77.9 °C, 78.0 °C, and 78.1 °C. The phylogenetic tree illustrated that the sequences of the current study included nine haplotypes. Tajima's D index analyses showed that cox1 gene in S. stercoralis isolates was negative (Tajima's D = - 0.27). CONCLUSION: The isolates were divided into five temperature groups. Although HRM assay compared to PCR sequencing identified more limited genetic changes, it revealed that the mean of Tm of the isolates from Hormozgan Province was lower than those of other provinces and represented specific haplotypes for this geographical region on the phylogenetic tree.


Assuntos
Filogenia , Reação em Cadeia da Polimerase em Tempo Real , Strongyloides stercoralis , Estrongiloidíase , Animais , Irã (Geográfico)/epidemiologia , Strongyloides stercoralis/genética , Strongyloides stercoralis/isolamento & purificação , Strongyloides stercoralis/classificação , Humanos , Estrongiloidíase/parasitologia , Estrongiloidíase/epidemiologia , DNA de Helmintos/genética , Temperatura de Transição , Haplótipos , Ciclo-Oxigenase 1/genética
8.
J Mater Chem B ; 12(15): 3694-3702, 2024 Apr 17.
Artigo em Inglês | MEDLINE | ID: mdl-38529581

RESUMO

Thermoresponsive shape memory polymers (SMPs) prepared from UV-curable poly(ε-caprolactone) (PCL) macromers have the potential to create self-fitting bone scaffolds, self-expanding vaginal stents, and other shape-shifting devices. To ensure tissue safety during deployment, the shape actuation temperature (i.e., the melt transition temperature or Tm of PCL) must be reduced from ∼55 °C that is observed for scaffolds prepared from linear-PCL-DA (Mn ∼ 10 kg mol-1). Moreover, increasing the rate of biodegradation would be advantageous, facilitating bone tissue healing and potentially eliminating the need for stent retrieval. Herein, a series of six UV-curable PCL macromers were prepared with linear or 4-arm star architectures and with Mns of 10, 7.5, and 5 kg mol-1, and subsequently fabricated into six porous scaffold compositions (10k, 7.5k, 5k, 10k★, 7.5k★, and 5k★) via solvent casting particulate leaching (SCPL). Scaffolds produced from star-PCL-tetraacrylate (star-PCL-TA) macromers produced pronounced reductions in Tm with decreased Mnversus those formed with the corresponding linear-PCL-diacrylate (linear-PCL-DA) macromers. Scaffolds were produced with the desired reduced Tm profiles: 37 °C < Tm < 55 °C (self-fitting bone scaffold), and Tm ≤ 37 °C (self-expanding stent). As macromer Mn decreased, crosslink density increased while % crystallinity decreased, particularly for scaffolds prepared from star-PCL-TA macromers. While shape memory behavior was retained and radial expansion pressure increased, this imparted a reduction in modulus but with an increase in the rate of degradation.


Assuntos
Poliésteres , Alicerces Teciduais , Temperatura de Transição , Osso e Ossos , Temperatura
9.
Macromol Rapid Commun ; 45(9): e2300704, 2024 May.
Artigo em Inglês | MEDLINE | ID: mdl-38346444

RESUMO

The isothermal melting behaviors of ultra-high molecular weight polyethylene (UHMWPE) with different entangled states (i.e., nascent and melt-crystallized samples) are studied. For two kinds of UHMWPE samples, the result shows that the relative content of survived crystals (Xs) exponentially decreases with time and reaches a constant value. It is suggested that such a melting behavior is related to the observed nonlinear growth of crystals induced by the kinetically rejected entanglements accumulated at the growth front. Additionally, the exponential decay of Xs with time provides a characteristic melting time (τ) for the melting process. Compared to the melt-crystallized UHMWPE, the τ value of nascent UHMWPE is generally longer even in a higher temperature range, which is mainly because the former has a larger entanglement density difference. Furthermore, these observations demonstrate that UHMWPEs with different entangled states have an analogous melting mechanism since they exhibit a similar melting activation energy (≈1300 kJ mol-1).


Assuntos
Cristalização , Polietilenos , Cinética , Polietilenos/química , Temperatura de Transição , Temperatura
10.
Int J Biol Macromol ; 262(Pt 1): 129684, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-38307741

RESUMO

Incorporation of growth factors, signaling molecules and drugs can be vital for the success of tissue engineering in complex structures such as the dentoalveolar region. This has led to the development of a variety of drug release systems. This study aimed to develop pNIPAM-methylcellulose microgels with different synthesis parameters based on a 23 full factorial design of experiments for this application. Microgel properties, including volume phase transition temperature (VPTT), hydrodynamic size, drug loading and release, and cytocompatibility were systematically evaluated. The results demonstrated successful copolymerization and development of the microgels, a hydrodynamic size ranging from ∼200 to ∼500 nm, and VPTT in the range of 34-39 °C. Furthermore, loading of genipin, capable of inducing odontoblastic differentiation, and its sustained release over a week was shown in all formulations. Together, this can serve as a solid basis for the development of tunable drug-delivering pNIPAM-methylcellulose microgels for specific tissue engineering applications.


Assuntos
Microgéis , Géis/química , Metilcelulose , Engenharia Tecidual , Temperatura de Transição
11.
Int J Pharm ; 653: 123895, 2024 Mar 25.
Artigo em Inglês | MEDLINE | ID: mdl-38346598

RESUMO

Amorphous solid dispersions (ASD) are known to enhance the absorption of poorly water-soluble drugs. In this work we synthesise well-defined Polyvinylpyrrolidone (PVP) to establish the impact of dispersity and chain-end functionality on the physical properties of Curcumin (CUR)/PVP ASD. Thermodynamic characterisation of synthesised PVP emphasises a strong effect of the dispersity on the glass transition temperature (Tg), 50 °C higher for synthesised PVP than for commercial PVP K12 of same molar mass. This increase of Tg affects the thermodynamic properties of CUR/PVP ASD successfully formulated up to 70 wt% of CUR by milling or solvent evaporation. The evolution of both the Tg and CUR solubility values versus CUR content points out the development of fairly strong CUR-PVP interactions that strengthen the antiplasticising effect of PVP on the Tg of ASD. However, for ASD formulated with commercial PVP this effect is counterbalanced at low CUR content by a plasticising effect due to the shortest PVP chains. Moreover, the overlay of the phase and state diagrams highlights the strong impact of the polymer dispersity on the stability of CUR/PVP ASD. ASD formulated with low dispersity PVP are stable on larger temperature and concentration ranges than those formulated with PVP K12.


Assuntos
Curcumina , Polímeros , Povidona , Solubilidade , Temperatura de Transição
12.
J Prosthet Dent ; 131(4): 708.e1-708.e8, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-38383280

RESUMO

STATEMENT OF PROBLEM: Removable dental prostheses require periodic relining with the loss of intaglio surface fit because of mucosal shape changes over time. Therefore, a new material with high adaptability to tissue changes over time would be beneficial. PURPOSE: This study focused on a shape-memory gel (SMG) that softens when heated, retains its shape when cooled, and returns to its original shape when reheated. The purpose was to optimize SMG for intraoral use by controlling the ratio of 2 acrylate monomers and to evaluate the changes in the shape memory and physical properties of SMG with temperature and to evaluate biocompatibility. MATERIAL AND METHODS: SMG specimens were synthesized using the following mixing ratios of 2 monomers, docosyl acrylate (DA) and stearyl acrylate (SA): 0:100, 25:75, 50:50, 75:25, and 100:0. SMG specimens were photopolymerized using a fluorescent light-polymerizing unit. To evaluate shape memory as a function of temperature, permanent deformation was measured based on the standardized compression set test for thermoplastic rubber. For evaluation of the physical properties and cytotoxicity, a 3-dimensionally printed denture base material was used as the control material. All assessments were compared between the groups by using 1-way analysis of variance followed by the Tukey-Kramer multiple comparison test (α=.05). RESULTS: SMGs with a higher amount of DA maintained their compressed shape at room and intraoral temperatures. However, the SMG matrices softened and recovered their original shapes above 60 °C. SMGs showed Shore A hardness equivalent to that of the denture-base polymer material at intraoral temperatures because of the high phase-transition temperature. The low water solubility of SMGs supported the biocompatibility test results. CONCLUSIONS: SMG, in which the phase-transition temperature was controlled by mixing acrylate monomers with different melting points, exhibited shape memory in the intraoral environment. The results indicate the feasibility of applying SMG for the fabrication of removable dental prostheses because of its high adaptability to tissue changes over time and biocompatibility.


Assuntos
Acrilatos , Prótese Dentária , Temperatura , Temperatura de Transição , Teste de Materiais
13.
J Chromatogr A ; 1717: 464690, 2024 Feb 22.
Artigo em Inglês | MEDLINE | ID: mdl-38309188

RESUMO

The extensive use of pesticides to control pest infestations has led to the development of analytical methods to determine pesticide residues in food matrices to prevent food exposure. However, most developed analytical methods do not consider impact on the environment in terms of the toxicity of the chemicals used and the amount of waste produced. An environmentally-friendly method, based on a miniaturized matrix solid-phase dispersion followed by high-performance liquid chromatography-tandem mass spectrometry, for the analysis of fourteen pesticides in tomatoes, was exploited. For the recovery of pesticides from tomato samples, a low transition temperature mixture (LTTM), containing choline chloride and sesamol 1:3 molar ratio, was employed. Extraction parameters like sample-to-dispersant ratio, extraction solvent volume and LTTM volume were optimized through a Box-Behnken design. The 1:4 sample-to-dispersant ratio, 900 µL of ethanol as extraction solvent and 50 µL of LTTM ensured the best result considering the pesticides' peak areas. The optimized analytical method was validated obtaining the following results: linearity range was between LOQ and 5 mg kg-1 with a minimum R2 of 0.9944 for tebufenozide, values in the range of 0.001-0.023 and 0.004-0.076 mg kg-1 were obtained for LOD and LOQ respectively, while peak areas intra-day and inter-day repeatability were maximum of 10.19 and 9.15 %, respectively. The analytical method was then applied to real samples studying whole, pulp and peel tomato pool. The analysis of whole and tomato pulp revealed the presence of seven and eight of the fourteen investigated pesticides, respectively. However, their concentration was lower than the limit of quantification. In tomato peel, five pesticides, namely dimethomorph, methoxyfenozide, pyraclostrobin, pyriproxyfen, and spiromesifen were quantified and their concentrations were below maximum residue levels.


Assuntos
Resíduos de Praguicidas , Praguicidas , Solanum lycopersicum , Praguicidas/análise , Cromatografia Líquida de Alta Pressão/métodos , Espectrometria de Massas em Tandem/métodos , Temperatura de Transição , Resíduos de Praguicidas/análise , Solventes/química , Extração em Fase Sólida/métodos
14.
Macromol Rapid Commun ; 45(9): e2300735, 2024 May.
Artigo em Inglês | MEDLINE | ID: mdl-38281084

RESUMO

The covalently cross-linked network gives thermosets superior thermal, mechanical, and electrical properties, which, however, squarely makes the large residual stress that is inevitably induced during preparation hardly relieved in the glassy state. In this work, an incredible reduction in residual stress is successfully achieved in bulk thermosets in the glassy state through introducing highly dynamic thiocarbamate bonds by "click" reactions of thiols and isocyanates. Due to the excellent dynamic behaviors of thiocarbamate bonds, local network rearrangement is achieved through thermal stimulation, while the strong 3D cross-linked network is well maintained. Ultimately, a decrease by 44% in residual stress is detected by simply annealing samples at 30 °C below glass transition temperature (Tg), during which they could well maintain more than 98.4% of the storage modulus. After the annealing, more uniform residual stress distribution is also observed, showing a 32% decline in sample standard deviation. However, the residual stress of epoxy resin, a typical thermoset as a reference, changes little even after annealing at Tg. The results prove it a feasible strategy to reduce residual stress in bulk thermosets in the glassy state by introducing proper dynamic covalent bonds.


Assuntos
Vidro , Vidro/química , Temperatura de Transição , Compostos de Sulfidrila/química , Estrutura Molecular , Isocianatos/química , Estresse Mecânico , Temperatura
15.
Biomacromolecules ; 25(2): 666-674, 2024 Feb 12.
Artigo em Inglês | MEDLINE | ID: mdl-38194667

RESUMO

Understanding and controlling the diffusion of ions and chemicals within the secondary plant cell walls are pivotal in various applications of biomasses. Recent studies have shown that inorganic ion diffusion through secondary cell walls is controlled by a moisture-induced glass transition in amorphous polysaccharides, including amorphous cellulose and hemicelluloses. Understanding the diffusion of ions in these structures has been the subject of numerous recent experiments; however, a deep understanding of the underlying mechanisms of interactions between ion atoms and water/hemicellulose molecules is still lacking. This study uses molecular dynamics simulations to elucidate the diffusion mechanisms of potassium and chloride ions in the cell walls under varying moisture content. The results reveal that a higher moisture content leads to the formation of solvent layers around the ions and reduces the charge interaction between the functional groups of wood polymers and ions. Hence, a higher moisture content results in an improved diffusion rate of ions within the domain. The simulation results also show that higher moisture content lowers the glass transition temperature, promoting diffusion of ions in the system. In contrast, increases in the ion concentration increase the glass transition temperature of the system and degrade the diffusion of ions in the system.


Assuntos
Vitrificação , Madeira , Temperatura de Transição , Madeira/metabolismo , Difusão , Parede Celular/química , Íons , Água/química , Temperatura
16.
Int J Pharm ; 651: 123807, 2024 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-38220121

RESUMO

It is generally accepted that water as a plasticizer can decrease the glass transition temperatures (Tgs) of amorphous drugs and drug excipient systems. However, previous studies suggest that water, as an anti-plasticizer, can increase the Tgs of co-amorphous systems of prilocaine (PRL) and lidocaine (LID). In order to investigate the intermolecular interactions between water and co-amorphous PRL-LID systems, Fourier transform infrared spectroscopy (FTIR) and principal component analysis (PCA) were conducted. Water was found to bind with the carbonyl groups of PRL and LID molecularly evenly in the hydrated co-amorphous PRL-LID systems. Quantum chemical simulations visually confirmed the interactions between water and co-amorphous PRL-LID systems. Furthermore, the physical stability of hydrated co-amorphous PRL-LID systems was improved due to the anti-plasticizing effect of water, compared with the anhydrous samples. The preference of water to interact with the carbonyl groups of PRL and LID as binding sites could be associated with the anti-plasticizing effect of water on the co-amorphous PRL-LID systems.


Assuntos
Lidocaína , Prilocaína , Prilocaína/química , Temperatura de Transição , Temperatura , Água , Espectroscopia de Infravermelho com Transformada de Fourier , Estabilidade de Medicamentos , Varredura Diferencial de Calorimetria , Solubilidade
17.
Environ Sci Pollut Res Int ; 31(7): 10296-10316, 2024 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-36719584

RESUMO

Ionic liquids (ILs), often known as green designer solvents, have demonstrated immense application potential in numerous scientific and technological domains. ILs possess high boiling point and low volatility that make them suitable environmentally benign candidates for many potential applications. The more important aspect associated with ILs is that their physicochemical properties can be effectively changed for desired applications just by tuning the structure of the cationic and/or anionic part of ILs. Furthermore, these eco-friendly designer materials can function as electrolytes or solvents depending on the application. Owing to the distinctive properties such as low volatility, high thermal and electrochemical stability, and better ionic conductivity, ILs are nowadays immensely used in a variety of energy applications, particularly in the development of green and sustainable energy storage and conversion devices. Suitable ILs are designed for specific purposes to be used as electrolytes and/or solvents for fuel cells, lithium-ion batteries, supercapacitors (SCs), and solar cells. Herein, we have highlighted the utilization of ILs as unique green designer materials in Li-batteries, fuel cells, SCs, and solar cells. This review will enlighten the promising prospects of these unique, environmentally sustainable materials for next-generation green energy conversion and storage devices. Ionic liquids have much to offer in the field of energy sciences regarding fixing some of the world's most serious issues. However, most of the discoveries discussed in this review article are still at the laboratory research scale for further development. This review article will inspire researchers and readers about how ILs can be effectively applied in energy sectors for various applications as mentioned above.


Assuntos
Líquidos Iônicos , Líquidos Iônicos/química , Solventes/química , Eletrólitos/química , Íons , Temperatura de Transição
18.
Int J Biol Macromol ; 256(Pt 2): 128507, 2024 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-38040144

RESUMO

With the increased environmental issues, advanced high-performance and multifunctional polymeric materials derived from biomass have tremendous attention due to the great potential to replace their traditional petroleum-based counterparts. In this work, a series of lignin graft copolymers, lignin-graft-poly(n-butyl acrylate-co-acrylic acid) (Lig-g-P(BA-co-AA)), were rationally prepared via reversible addition-fragmentation chain transfer (RAFT) polymerization. These lignin-based copolymers demonstrate good thermal stability and tunable glass transition temperature (Tg) values. The mechanical performance, including tensile strength, extensibility, Young's modulus, and toughness can be facilely adjusted by the BA/AA feed ratio and lignin content during polymerization. Owing to the extraordinary photothermal conversion ability of lignin, the Lig-B550 copolymer, containing 11.8 wt% lignin content, shows excellent stimulus-healing behavior within 1 min with a 97.1 % healing efficiency under near-infrared (NIR) laser irradiation. Moreover, the Lig-g-P(BA-co-AA) copolymers exhibit remarkable adhesion property, broadening their potential applications in the adhesive area. This grafting strategy is versatile and efficient, conferring the resultant lignin-based composite elastomers with dramatically enhanced mechanical properties and unprecedented photothermal behavior, which can inspire the further development of strong lignin-based sustainable elastomers.


Assuntos
Elastômeros , Lignina , Polímeros , Temperatura , Temperatura de Transição
19.
Eur J Pharm Biopharm ; 194: 1-8, 2024 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-38029940

RESUMO

Molecular mobility in form of alpha and beta relaxations is considered crucial for characterization of amorphous lyophilizates and reflected in the transition temperatures Tgα and Tgß. Based on an overview of applied methods to study beta relaxations, Dynamic Mechanical analysis was used to measure Tgα and Tgß in amorphous freeze-dried samples. Lysozyme and trehalose as well as their mixtures in varying ratios were investigated. Three different residual moisture levels, ranging from roughly 0.5-7 % (w/w), were prepared via equilibration of the freeze-dried samples. Known plasticising effects of water on Tgα were confirmed, also via differential scanning calorimetry. In addition and contrary to expectations, an influence of water on the Tgß also was observed. On the other hand, an increasing amount of trehalose lowered Tgα but increased Tgß showing that Tgα and Tgß are not paired. The findings were interpreted with regard to their underlying molecular mechanisms and a correlation with the known influences of water and trehalose on stability. The results provide encouraging hints for future stability studies of freeze-dried protein formulations, which are urgently needed, not least for reasons of sustainability.


Assuntos
Muramidase , Trealose , Muramidase/química , Trealose/química , Água , Liofilização/métodos , Temperatura de Transição , Varredura Diferencial de Calorimetria
20.
J Mech Behav Biomed Mater ; 150: 106337, 2024 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-38154364

RESUMO

OBJECTIVES: To conduct a physiochemical and mechanical material analysis on 3D printed shape-memory aligners in comparison to thermoformed aligners. MATERIALS AND METHODS: Four materials were examined, including three thermoformed materials: CA Pro (CP), Zendura A (ZA), Zendura FLX (ZF), and one 3D printed material: Tera Harz (TC-85). Rectangular strips measuring 50 × 10 × 0.5 mm were produced from each material. Five tests were conducted, including differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), shape recovery tests, three-points bending (3 PB), and Vickers surface microhardness (VH). RESULTS: DSC recorded glass transition temperatures (Tg) at 79.9 °C for CP, 92.2 °C for ZA, 107.1 °C for ZF, and 42.3 °C for TC-85. In DMA analysis at 20-45 °C, a prominent decrease in storage modulus was observed, exclusively for TC-85, as the temperature increased. Notably, within the temperature range of 30-45 °C, TC-85 exhibited substantial shape recovery after 10 min, reaching up to 86.1 %, while thermoformed materials showed minimal recovery (1.5-2.9 %). In 3 PB test (at 30, 37, 45 °C), ZA demonstrated the highest force at 2 mm bending, while TC-85 exhibited the lowest. Regarding VH at room temperature, there was a significant decrease for both ZA and ZF after thermoforming. ZA had the highest hardness, followed by ZF and TC-85, with CP showing the lowest values. CONCLUSIONS: TC-85 demonstrates exceptional shape memory at oral temperature, improving adaptation, reducing force decay, and enabling, together with its higher flexibility, extensive tooth movement per step. Additionally, it maintains microhardness similar to thermoformed sheets, ensuring the durability and effectiveness of dental aligners. CLINICAL RELEVANCE: The 3D printed aligner material with shape memory characteristics (4D aligner) has revolutionized the orthodontic aligner field. It showed mechanical properties more suitable for orthodontic treatment than thermoforming materials. Additionally, it offers enhanced control over aligner design and thickness, while optimizing the overall workflow. It also minimizes material wastage, and reduces production expenses.


Assuntos
Materiais Inteligentes , Fenômenos Mecânicos , Vidro , Temperatura de Transição , Impressão Tridimensional
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA