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1.
J Colloid Interface Sci ; 606(Pt 2): 961-970, 2022 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-34487943

RESUMO

The usage of single-use face masks (SFMs) has increased since the outbreak of the coronavirus pandemic. However, non-degradability and mismanagement of SFMs have raised serious environmental concerns. Moreover, both melt-blown and nanofiber-based mask filters inevitably suffer from poor filtration performance, like a continuous decrease in the removal efficiency for particulate matter (PM) and weak breathability. Herein, we report a new method to create biodegradable and reusable fibrous mask filters. The filter consists of a true nanoscale bio-based poly(lactic acid) (PLA) fiber (an average size of 37 ± 4 nm) that is fabricated via electrospinning of an extremely dilute solution. Furthermore, we designed a multiscale structure with integrated features, such as low basis weight (0.91 g m-2), small pore size (0.73 µm), and high porosity (91.72%), formed by electrospinning deposition of true nanoscale fibers on large pore of 3D scaffold nanofiber membranes. The resultant mask filter exhibited a high filtration efficiency (PM0.3-99.996%) and low pressure drop (104 Pa) superior to the commercial N95 filter. Importantly, this filter has a durable filtering efficiency for PM and natural biodegradability based on PLA. Therefore, this study offers an innovative strategy for the preparation of PLA nanofibers and provides a new design for high-performance nanofiber filters.


Assuntos
Nanofibras , Filtração , Material Particulado , Poliésteres
2.
J Colloid Interface Sci ; 606(Pt 2): 1140-1152, 2022 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-34492457

RESUMO

Understanding the microstructural parameters of amphiphilic copolymers that control the formation and structure of aggregated colloids (e.g., micelles) is essential for the rational design of hierarchically structured systems for applications in nanomedicine, personal care and food formulations. Although many analytical techniques have been employed to study such systems, in this investigation we adopted an integrated approach using non-interfering techniques - diffusion nuclear magnetic resonance (NMR) spectroscopy, dynamic light scattering (DLS) and synchrotron small-angle X-ray scattering (SAXS) - to probe the relationship between the microstructure of poly(ethylene glycol-b-caprolactone) (PEG-b-PCL) copolymers [e.g., block molecular weight (MW) and the mass fraction of PCL (fPCL)] and the structure of their aggregates. Systematic trends in the self-assembly behaviour were determined using a large family of well-defined block copolymers with variable PEG and PCL block lengths (number-average molecular weights (Mn) between 2 and 10 and 0.5-15 kDa, respectively) and narrow dispersity (Ð < 1.12). For all of the copolymers, a clear transition in the aggregate structure was observed when the hydrophobic fPCL was increased at a constant PEG block Mn, although the nature of this transition is also dependent on the PEG block Mn. Copolymers with low Mn PEG blocks (2 kDa) were observed to transition from unimers and loosely associated unimers to metastable aggregates and finally, to cylindrical micelles as the fPCL was increased. In comparison, copolymers with PEG block Mn of between 5 and 10 kDa transitioned from heterogenous metastable aggregates to cylindrical micelles and finally, well-defined ellipsoidal micelles (of decreasing aspect ratios) as the fPCL was increased. In all cases, the diffusion NMR spectroscopy, DLS and synchrotron SAXS results provided complementary information and the grounds for a phase diagram relating copolymer microstructure to aggregation behaviour and structure. Importantly, the absence of commonly depicted spherical micelles has implications for applications where properties may be governed by shape, such as, cellular uptake of nanomedicine formulations.


Assuntos
Poliésteres , Polietilenoglicóis , Caproatos , Lactonas , Micelas , Espalhamento a Baixo Ângulo , Difração de Raios X
3.
J Colloid Interface Sci ; 606(Pt 2): 1842-1851, 2022 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-34507175

RESUMO

HYPOTHESIS: The crystallisation of biosourced ferulic acid derivatives - Bis-O-feruloyl-1,4-butanediol (BDF) - in a polylactic acid (PLA) matrix produces thermoplastic elastomeric blends that are transparent and biodegradable. Elastomeric and transparency are controlled by the domain size. PLA-BDF blends up to a threshold BDF concentration providing elastomeric properties show no evidence of BDF crystallisation. Heat treatment weakens the PLA-BDF interaction, give BDF molecules mobility to interact with nearby BDF molecules, leading to BDF nano-crystallisation. EXPERIMENTS: PLA-BDF blends were synthesised by hot-melt processing by mixing pure PLA with different concentrations of BDF (0-40 wt%) at 180 °C for 13 min. One set of blends was annealed at 50 °C for 24 h and compared with the unannealed set. The BDF crystallisation in the blends is studied by combining SAXS, SEM, XRD and Polarised Optical Microscopy. Monte-Carlo simulations were performed to validate SAXS data analysis. FINDINGS: Unannealed PLA-BDF blends of up to the threshold of 20 wt% BDF are dominated by the semicrystalline behaviour of PLA, without any trace of BDF crystallisation. Surprisingly, the PLA-BDF 40 wt% blend shows BDF crystallisation in the form of large and nanoscale structures bonded together by weak interparticle interaction. At concentrations up to 20 wt%, the BDF molecules are homogenously dispersed and bonded with PLA. Increasing BDF to 40 wt% brings the BDF molecules close enough to crystallise at room temperature, as the BDF molecules are still bonded with the PLA network. Annealing of PLA-BDF blends led to BDF nanocrystallisation and self-assembling in the PLA network. Both BDF nanoparticle size and interparticle distance decrease as the BDF concentration increases. However, the number density of BDF nanocrystals increases. The formed BDF nanocrystals have size ranging between 100 and 380 Å with interparticle distance of 120-180 Å. The structure factor and potential mean force confirm the strong interparticle interaction at the higher BDF concentration. Heat treatment weakens the PLA -BDF interaction, which provides mobility to the BDF molecules to change conformation and interact with the nearby BDF molecules, leading to BDF crystallisation. This novel BDF crystallisation and self-assembly mechanism can be used to develop biodegradable shape memory PLA blends for biomedical, shape memory, packaging and energy applications.


Assuntos
Poliésteres , Polímeros , Ácidos Cumáricos , Espalhamento a Baixo Ângulo , Difração de Raios X
4.
Chemosphere ; 286(Pt 3): 131905, 2022 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-34426289

RESUMO

Effective utilization of photoexcited electrons and holes is always a challenge in photocatalytic reactions. Herein, we reported ternary NixCo1-xP/reduced graphene oxide/g-C3N4 (NixCo1-xP/rGO/CN) composite as a photocatalyst for synergistic poly(lactic acid) photoreforming and H2 generation in alkaline aqueous solution. The rate of H2 production over the optimal 15Ni0·1Co0·9P/rGO/CN reached 576.7 µmol h-1 g-1, which is 3.6 times as high as binary 15Ni0·1Co0·9P/CN composite. The apparent quantum efficiency of the optimal 15Ni0·1Co0·9P/rGO/CN was 1.7% at λ = 420 nm monochromatic light. Mott-Schottky analysis suggested that the photogenerated electrons transfer along the pathway of CN→rGO→Ni0·1Co0·9P, where rGO and Ni0·1Co0·9P functioned as the medium for electron transporting and reaction site for H2 generation, respectively. Meanwhile, poly(lactic acid) was photoreformed into formate and acetate by the photogenerated holes and hydroxyl radical. This work demonstrates that ternary NixCo1-xP/rGO/CN composite can be applied as a cheap and promising photocatalyst for synergistic plastic photoreforming and H2 generation.


Assuntos
Grafite , Hidrogênio , Catálise , Poliésteres
5.
J Colloid Interface Sci ; 607(Pt 1): 34-44, 2022 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-34492351

RESUMO

Among the strategies to fight cancer, multi-therapeutic approaches are considered as a wise choice to put in place multiple weapons to suppress tumors. In this work, to combine chemotherapeutic effects to magnetic hyperthermia when using biocompatible scaffolds, we have established an electrospinning method to produce nanofibers of polycaprolactone loaded with magnetic nanoparticles as heat mediators to be selectively activated under alternating magnetic field and doxorubicin as a chemotherapeutic drug. Production of the fibers was investigated with iron oxide nanoparticles of peculiar cubic shape (at 15 and 23 nm in cube edges) as they provide benchmark heat performance under clinical magnetic hyperthermia conditions. With 23 nm nanocubes when included into the fibers, an arrangement in chains was obtained. This linear configuration of magnetic nanoparticles resemble that of the magnetosomes, produced by magnetotactic bacteria, and our magnetic fibers exhibited remarkable heating effects as the magnetosomes. Magnetic fiber scaffolds showed excellent biocompatibility on fibroblast cells when missing the chemotherapeutic agent and when not exposed to magnetic hyperthermia as shown by viability assays. On the contrary, the fibers containing both magnetic nanocubes and doxorubicin showed significant cytotoxic effects on cervical cancer cells following the exposure to magnetic hyperthermia. Notably, these tests were conducted at magnetic hyperthermia field conditions of clinical use. As here shown, on the doxorubicin sensitive cervical cancer cells, the combination of heat damage by magnetic hyperthermia with enhanced diffusion of doxorubicin at therapeutic temperature are responsible for a more effective oncotherapy.


Assuntos
Hipertermia Induzida , Nanopartículas de Magnetita , Neoplasias , Linhagem Celular Tumoral , Doxorrubicina/farmacologia , Compostos Férricos , Campos Magnéticos , Poliésteres
6.
Sci Total Environ ; 803: 150033, 2022 Jan 10.
Artigo em Inglês | MEDLINE | ID: mdl-34492486

RESUMO

In this study, a novel biodegradable PHBV/PLA/rice hulls (PPRH) composite was applied and tested as biofilm attachment carrier and carbon source in two bioreactors for biological denitrification process. The denitrification performance, effect of operational conditions and microbial community structure of PPRH biofilm were evaluated. The batch experiment results showed that PPRH-packed bioreactor could completely remove 50 mg L-1 of NO3--N at natural pH (ca. 7.5) and room temperature. The continuous flow experiments indicated that high NO3--N removal efficiency (77%-99%) was achieved with low nitrite (<0.48 mg L-1) and ammonia (<0.81 mg L-1) accumulation, when influent NO3--N concentration was 30 mg L-1 and hydraulic retention time was 2-6 h. Furthermore, the microbial community analysis indicated that bacteria belonging to genus Diaphorobacter in phylum Proteobacteria were the most dominant and major denitrifiers in denitrification. In summary, PPRH composite was a promising carbon source for biological nitrate removal from water and wastewater.


Assuntos
Comamonadaceae , Microbiota , Oryza , Reatores Biológicos , Carbono , Desnitrificação , Nitratos/análise , Nitrogênio , Poliésteres , Águas Residuárias
7.
J Hazard Mater ; 421: 126716, 2022 01 05.
Artigo em Inglês | MEDLINE | ID: mdl-34333407

RESUMO

With the continuous pressure of water contamination caused by textile industry, loose nanofiltration (LNF) membranes prepared by green materials with an extraordinary water permeability are highly desirable for the recovery and purification of dyes and salts. In this work, low-pressure LNF membranes with ultrahigh permeability were fabricated via one-step interfacial polymerization (IP), in which inexpensive natural carbohydrate-derived sugars with large size and low reactivity were utilized as aqueous monomers to design selective layer. A systematic characterization by chemical analysis and optical microscopy demonstrated that the formed polyester film features not only loosen the structure, but also results in a hydrophilic and negatively charged surface. The optimized sucrose-based membrane (Su0.6/TMC0.1) with an excellent water permeability of 52.4 LMH bar-1 was found to have a high rejection of dyes and a high transmission of salts. In addition, the sugar-based membrane manifested an excellent anti-fouling performance and long-term stability. Furthermore, the non-optimized Gl0.6/TMC0.1 and Ra0.6/TMC0.1 membranes also shown a high water permeability, while maintaining a competitive dye/salt separation performance, which confirmed the universal applicability of the membrane design principle. Therefore, the proposed new strategy for preparing next-generation LNF membranes can contribute towards the textile wastewater treatment.


Assuntos
Corantes , Purificação da Água , Carboidratos , Membranas Artificiais , Poliésteres
8.
Food Chem ; 369: 130950, 2022 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-34474288

RESUMO

Naringenin, a lipophilic flavanone of citrus fruits, was encapsulated for enhanced bioavailability using biodegradable polymers of polylactic acid/polyvinyl alcohol (PLA/PVA) as well as zein/pectin as P/P-Nar-NPs and Z/P-Nar-NPs, respectively. The formulation variables were optimized using response surface methodology to achieve smaller particle size with higher surface charge and encapsulation efficiencies. The optimized formulations were physically characterized by SEM, FTIR, TGA and XRD techniques. Compared to Z/P-Nar-NPs, the P/P-Nar-NPs had better encapsulation efficiency and sustained release of naringenin under simulated gastrointestinal conditions. Furthermore, the oral administration of single dose of free and nanoforms of naringenin in rats (90 mg/kg b.wt) showed higher efficacy of PLA/PVA in improving the relative bioavailability of naringenin (4.7-fold) as compared to the zein/pectin polymer (1.9-fold). Overall, the present study provides insights into the formulation performance of the encapsulated bioactive compound under different polymeric matrices.


Assuntos
Flavanonas , Nanopartículas , Zeína , Animais , Disponibilidade Biológica , Portadores de Fármacos , Tamanho da Partícula , Pectinas , Poliésteres , Álcool de Polivinil , Ratos
9.
Food Chem ; 369: 130956, 2022 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-34479016

RESUMO

Biodegradable active packaging was produced by compounding nisin (3, 6 and 9%) and nisin-ethylenediaminetetraacetic acid (EDTA) (3 and 6%) mixtures with poly(butylene adipate terephthalate) and thermoplastic starch blends (PBAT/TPS) by blown-film extrusion. Nisin and EDTA interacted with polymers, involving CO stretching of ester bonds and increased compatibility. This plasticized the films and modified the crystallinity, surface roughness and thermal relaxation behavior. Barrier properties were improved due to modified hydrophilic-hydrophobic properties, compact structures and crystallites that restricted vapor and oxygen permeation. PBAT/TPS films containing EDTA and nisin effectively inhibited lipid degradation in pork tissues corresponding with stabilizing the CO ester bond of triacylglycerol. Microbial growth was also inhibited, particularly in EDTA-containing films up to 1.4 log. Inactivation of microorganisms stabilized redness and delayed meat discoloration, preserving the quality of packaged pork. Interaction between nisin, EDTA and polymers modified the morphology and film properties and functionalized biodegradable food packaging to inactivate microorganisms.


Assuntos
Nisina , Carne de Porco , Ácido Edético , Poliésteres , Amido
10.
Bioresour Technol ; 343: 126066, 2022 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-34626765

RESUMO

In this study, the fluctuating profiles of physicochemical and microbial characterizations along different filling heights of continuously up-flow solid-phase denitrification (SPD) columns packed with polycaprolactone (PCL) were investigated. It was found both the PCL filling area and non-filling area made significant contributions to treatment performance and denitrification mainly occurred near the bottom of the filling column. Nitrate displayed a high proportional removal (≥98.7%) among all the cases except the one with the lowest filling ratio (FR30) and highest NLR (3.99 ± 0.12 gN/(L·d)), while nitrite and ammonium displayed a weak accumulation in final effluents (nitrite ≤ 0.40 mg/L; ammonium ≤ 0.98 mg/L). The intensity of PCL hydrolysis in the top substrate was stronger than those in the middle or bottom. Both dissimilatory nitrate reduction to ammonium (DNRA) and microbial lysis contributed to ammonium accumulation, and nitrate was mainly removed via traditional denitrification and DNRA. JGI_0000069-P22_unclassified and Gracilibacteria_unclassified might contribute to denitrification.


Assuntos
Compostos de Amônio , Desnitrificação , Nitratos , Nitritos , Nitrogênio , Poliésteres
11.
Bioresour Technol ; 343: 126119, 2022 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-34653627

RESUMO

In this study, techno-economic analysis of the sustainable production of polylactic acid (PLA) and biodiesel from Food Waste (FW), with a plant capacity of 50 tons/day, was investigated. In addition, FW of four countries (China, India, Brazil, and the USA) with different compositions of water, protein, lipid and carbohydrate were proposed. Each country has different PLA production rates based on carbohydrate and biodiesel production based on fat. In this study, the FW composition of the USA shows better economic feasibility than other countries. The actual minimum selling price is 6.53 (China), 5.35 (India), 4.75 (Brazil), and 4.29 (US) $/kg. The uncertainty of the MSP was analyzed based on various input limits. The sensitivity analysis was conducted based on biodiesel-selling price, PLA-selling price, income tax, and project lifetime on techno-economic analysis parameters, such as ROI, payback period, IRR and NPV were investigated.


Assuntos
Biocombustíveis , Eliminação de Resíduos , Alimentos , Poliésteres
12.
Sci Total Environ ; 805: 150181, 2022 Jan 20.
Artigo em Inglês | MEDLINE | ID: mdl-34537709

RESUMO

Establishing the emission profile of volatile organic compounds generated during fused deposition modeling 3D printing using polymer filaments is important in terms of both understanding the processes taking place during thermal degradation of thermoplastics, and assessing the user's exposure to potentially harmful volatiles. However, obtaining detailed, real-time qualitative and quantitative results poses a challenge. In this paper solid-phase microextraction-gas chromatography-time-of-flight mass spectrometry and proton transfer reaction time-of-flight mass spectrometry were used to identify and monitor the emission of volatiles during thermal degradation of polylactide filaments and during 3D printing. Filaments of two different grades and three colours were used. It was possible to obtain detailed, time- and temperature-resolved emission profiles of the main products of thermal decomposition of lactide and polylactide 3D printing filaments at concentration levels of a few µg/g. This revealed different temperature-dependent emission characteristics of particular volatiles, such as, among others, lactide, acetaldehyde, acetic acid, and 2-butanone between various polylactide 3D printing filaments. This approach can be used to monitor the emission associated with printing with various other types of polymer 3D printing materials.


Assuntos
Compostos Orgânicos Voláteis , Cromatografia Gasosa-Espectrometria de Massas , Poliésteres , Impressão Tridimensional , Compostos Orgânicos Voláteis/análise
13.
Acta Ortop Mex ; 35(2): 125-131, 2021.
Artigo em Espanhol | MEDLINE | ID: mdl-34731911

RESUMO

INTRODUCTION: There are different pathologies of the lumbar spine that condition a biomechanical and clinical instability for its treatment, various stabilization techniques have been carried out that try to preserve the movement and the transmission of load of the affected segment such as the interspinatus ligamentplasty with Dallos® fiber. OBJECTIVE: To show the biomechanical variations of functional segment of lumbar spine of pigs, before and after performing the discectomy and ligamentoplasty with Dallos® fiber. MATERIAL AND METHODS: The lumbar segment was mounted in a servo-hydraulic multiaxial simulator. Mobility ranges of flexion, extension, lateral flexion and axial rotations were simulated under three conditions: 1. Natural segment, 2. Discectomy segment, and 3. Disectomized segment plus ligamentoplasty with Dallos® fiber. The mobility ranges are made up to a torque of 7.5 N-m The data of the torques and mobility ranges was collected in the simulator program and the results of the biomechanical changes between the three conditions described were plotted. RESULTS: It was shown that lumbar biomechanics is affected after discectomy mainly in flexion and extension. In the left axial bending and rotation movements, an alteration of torque and mobility ranges was found. CONCLUSIONS: The ligamentoplasty recovers part of the stability lost after discectomy preserving part of the disc height without reaching to equalize the movements as in the natural segment. After discectomy the distribution of force suggests that residual instability with ligament plasty may represent facet overload.


Assuntos
Discotomia , Poliésteres , Animais , Fenômenos Biomecânicos , Vértebras Lombares/cirurgia , Amplitude de Movimento Articular , Suínos
14.
J Nanosci Nanotechnol ; 21(6): 3291-3298, 2021 06 01.
Artigo em Inglês | MEDLINE | ID: mdl-34739784

RESUMO

In this paper, a simple and effective method to prepare Ag-Ce/ZnO nanorods photocatalyst and grow them controllably on modified polyester fabrics was presented to fabricate multifunctional textiles. Analytical grade zinc acetate dihydrate and sodium hydroxide were used as the main raw materials to prepare Ag-Ce/ZnO nanorods. Morphological, structural and chemical characterization of the Ag-Ce/ZnO nanorods was performed by XRD, UV-vis and other spectroscopies. The results showed that the Ag-Ce/ZnO nanorods had a hexagonal wurtzite structure. After 60 minutes of irradiation under ultraviolet light, the Ag-Ce/ZnO nanorods showed a percentage photodegradation of 93.14% for a methylene blue (MB) solution. Modified polyester fabrics covered with the Ag-Ce/ZnO nanorods were then prepared in a water bath. By a series of tests, it was observed that the Ag-Ce/ZnO nanorods on the modified polyester surface were neatly arranged and had good photocatalytic properties. Moreover, the UPF of the modified polyester fabric after finishing increased from 30.4 to 877.2. The multifunctional properties of the finished fabric exhibited good durability.


Assuntos
Nanotubos , Óxido de Zinco , Catálise , Poliésteres , Água
15.
Nanoscale ; 13(43): 18363-18373, 2021 Nov 11.
Artigo em Inglês | MEDLINE | ID: mdl-34723308

RESUMO

As a new nanotechnology of mechanical energy harvesting and self-powered sensing, triboelectric nanogenerators (TENGs) have been explored as a new path of using various low-frequency disordered mechanical energies in the surrounding environment to provide power and/or sensing. However, the research of TENGs that provide full flexibility and environmental friendliness is still limited. Herein, a flexible single-electrode TENG (S-TENG) based on polyester conductive cloth as the working electrode is developed to harvest human motion energy for powering light emitting diodes (LEDs) and portable electronics. The flat conductive cloth was wrapped in a flexible elastomer. Defatted cowhide was firstly selected as a friction positive charge material for TENGs. When the size of the fabricated S-TENG is 40 × 100 mm2, high output performance has been achieved and it can generate an open-circuit voltage of 534 V and a power density of 230 mW m-2 at an operation frequency of 3.0 Hz. After integrating with a rectifier, the S-TENG can power 240 LEDs, charge various capacitors, and drive an electronic watch or a calculator. Moreover, the S-TENG can harvest the biomechanical energy of wrist movement, hand tapping, and human walking. Meanwhile, the S-TENG as a self-powered sensor can be employed to monitor subtle signals of human physiological activities, such as finger motion, facial masseter activity, and diaphragmatic breathing. Additionally, the S-TENG can be attached to clothes (such as wool coats, polyamide sweaters) to harvest the energy of cuff movement. Therefore, this work provides new insights for clean power sources of skin-mounted electronics and promotes the development of a sustainable energy supply for wearable and portable electronics.


Assuntos
Nanotecnologia , Poliésteres , Condutividade Elétrica , Fontes de Energia Elétrica , Eletrônica , Humanos
16.
Phys Chem Chem Phys ; 23(34): 19011-19021, 2021 Sep 14.
Artigo em Inglês | MEDLINE | ID: mdl-34612439

RESUMO

The design of mixed polymeric micelles by a combination of two or more dissimilar polymers is a potential strategy to achieve multiple stimuli-response for anti-cancer drug delivery. However, their drug loading co-micellization behavior and multiple stimuli-responsive drug release mechanism have been poorly understood at the mesoscopic level, especially in the system that involves reduction-response due to the difficulty of simulation on the cleavage of chemical bonds. In this work, the co-micellization behavior, drug distribution regularities and dual pH/reduction-responsive drug release process of mixed micelles formed by disulfide-linked polycaprolactone-b-polyethylene glycol methyl ether methacrylate (PCL-SS-PPEGMA) and poly(ethylene glycol) methyl ether-b-poly(N,N-diethylamino ethyl methacrylate) (PDEA-PPEGMA) were studied by dissipative particle dynamics (DPD) mesoscopic simulations. A dedicated bond-breaking script was employed to accomplish the disulfide bond-breaking simulations. The results showed that PCL55-SS-PPEGMA10 and PDEA34-PPEGMA11 could be well mixed to form superior DOX-loaded micelles with good drug-loading capacity and drug-controlled release performance. To prepare the DOX-loaded micelles with optimized properties, the simulation results suggested the feed ratio of DOX:PCL55-SS-PPEGMA10:PDEA34-PPEGMA11 set to 3:4:4. Compared with the two single stimuli-response, the dual pH/reduction-response process perfectly combined both pH-response and reduction-response together, providing a higher release rate of DOX. Therefore, this study provides theoretical guidance aimed at the property optimization and micellar structure design of the dual pH/reduction-responsive mixed micelles.


Assuntos
Antibióticos Antineoplásicos/química , Doxorrubicina/química , Metacrilatos/química , Simulação de Dinâmica Molecular , Poliésteres/química , Polietilenoglicóis/química , Portadores de Fármacos/química , Concentração de Íons de Hidrogênio , Micelas , Estrutura Molecular , Oxirredução
17.
Rozhl Chir ; 100(9): 435-439, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34649452

RESUMO

INTRODUCTION: The development of an ideal dressing for wound healing remains an unresolved issue. Thanks to the development of electrospinning technology, polymers in the form of nanofibers have come to the forefront of research interest. A modern and very promising dressing material is a “nonwoven” based on nanofibers of the synthetic polymer polylactide (PLA). The aim of this work was to assess the regenerative abilities of PLA in a standardized wound in a porcine model and compare our results to the literature data. METHODS: We applied PLA-based nanofiber dressings to the standardized wounds created in the porcine model. On the third, tenth, seventeenth and twenty-fourth days after the formation of the defect, we changed the wound dressing while taking a tissue sample for histopathological examination. We continuously monitored serum levels of acute phase proteins. RESULTS: PLA stimulated an inflammatory response. From the third day, the thickness of the fibrin layer with granulocytes increased. It reached its maximum values on the tenth day (mean 340 μm); at the same time the level of serum amyloid A, as a marker of inflammation, culminated. The individual phases of healing intertwined. The highest thickness values of the granulation tissue with cellular connective tissue (diameter 8463 μm) were reached on the seventeenth day. On the twenty-fourth day, the defects were healed macroscopically with a mean reepithelialization layer of 9913 μm. CONCLUSION: PLA-based nanofiber dressing potentiates the inflammatory, proliferative and reepithelialization phases of healing. Its structure perfectly mimics the extracellular matrix and serves as a 3D network for the growth and interaction of cellular elements. In addition to biocompatibility, PLA has a unique ability of two-phase biodegradation. It is a promising material for industrial production of dressing materials. Most of the available studies were performed in vitro. In vivo comparative studies approximating the use of PLA to daily practice are still missing.


Assuntos
Nanofibras , Animais , Bandagens , Poliésteres , Suínos , Cicatrização
18.
Int J Mol Sci ; 22(19)2021 Sep 27.
Artigo em Inglês | MEDLINE | ID: mdl-34638747

RESUMO

Amphiphilic copolymers with pendant functional groups in polyester segments are widely used in nanomedicine. These enriched functionalities are designed to form covalent conjugates with payloads or provide additional stabilization effects for encapsulated drugs. A general method is successfully developed for the efficient preparation of functional biodegradable PEG-polyester copolymers via click chemistry. Firstly, in the presence of mPEG as initiator, Sn(Oct)2-catalyzed ring-opening polymerization of the α-alkynyl functionalized lactone with D,L-lactide or ε-caprolactone afforded linear mPEG-polyesters bearing multiple pendant alkynyl groups. Kinetic studies indicated the formation of random copolymers. Through copper-catalyzed azide-alkyne cycloaddition reaction, various small azido molecules with different functionalities to polyester segments are efficiently grafted. The molecular weights, polydispersities and grafting efficiencies of azido molecules of these copolymers were investigated by NMR and GPC. Secondly, it is demonstrated that the resulting amphiphilic functional copolymers with low CMC values could self-assemble to form nanoparticles in aqueous media. In addition, the in vitro degradation study and cytotoxicity assays indicated the excellent biodegradability and low cytotoxicity of these copolymers. This work provides a general approach toward the preparation of functional PEG-polyester copolymers in a quite efficient way, which may further facilitate the application of functional PEG-polyesters as drug delivery materials.


Assuntos
Plásticos Biodegradáveis , Química Click , Sistemas de Liberação de Medicamentos , Poliésteres , Polietilenoglicóis/química , Plásticos Biodegradáveis/síntese química , Plásticos Biodegradáveis/química , Plásticos Biodegradáveis/farmacocinética , Plásticos Biodegradáveis/farmacologia , Catálise , Células HeLa , Humanos , Poliésteres/síntese química , Poliésteres/química , Poliésteres/farmacocinética , Poliésteres/farmacologia , Compostos de Estanho/química
19.
Mater Sci Eng C Mater Biol Appl ; 130: 112434, 2021 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-34702519

RESUMO

Bone defects arising from injury and/or disease are a common and debilitating clinical lesion. While the development of tissue microenvironments utilizing biomimetic constructs is an emerging approach for bone tissue engineering. In this context, bioactive glass nanoparticles (BGNPs) were embedded within polycaprolactone (PCL) scaffolds. The scaffolds exhibit an engineered unidirectional pore structure which are surface activated via oxygen plasma to allow immobilization of simvastatin (SIM) on the pore surface. Microscopic observation indicated the surface modification did not disturb the lamellar orientation of the pores improving the biomimetic formation of hydroxyapatite. Mathematically modelled release profiles reveal that the oxygen plasma pre-treatment can be utilized to modulate the release profile of SIM from the scaffolds. With the release mechanism controlled by the balance between the diffusion and erosion mechanisms. Computational modelling shows that Human Serum Albumin and Human α2-macroglobulin can be utilized to increase SIM bioavailability for cells via a molecular docking mechanism. Cellular studies show positive MG-63 cell attachment and viability on optimized scaffolds with alkaline phosphatase activity enhanced along with enhanced expression of osteocalcoin biomarker.


Assuntos
Preparações Farmacêuticas , Engenharia Tecidual , Biomimética , Humanos , Simulação de Acoplamento Molecular , Osteogênese , Poliésteres , Tecidos Suporte
20.
Mater Sci Eng C Mater Biol Appl ; 130: 112471, 2021 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-34702545

RESUMO

Hydrogen sulfide (H2S) has been as an essential gasotransmitter and a potential therapeutic approach for several biomedical treatments such as cardiovascular disorders, hypertension, and other diseases. The endogenous and exogenous H2S also plays a crucial role in the bone anabolic process and a protective mechanism in cell signalling. In this study, we have utilized two types of polymers, polycaprolactone (PCL) and gelatin (Gel), for the fabrication of JK-2 (H2S donor) loaded nanofibrous scaffold via electrospinning process for bone healing and bone tissue engineering. Comparing the PCL/Gel and PCL/Gel-JK-2 scaffolds, the latter demonstrated enhanced cell adhesion and proliferation capabilities. Furthermore, both experimental scaffolds have been subjected to an in vivo experiment for 4 and 8 weeks in a bone-defect model of a rabbit to determine their biological responses under physiological conditions. There was an obvious increase in bone regeneration in the PCL/Gel-JK-2 group compared to the control and PCL/Gel groups. These results indicate the use of PCL/Gel scaffolds loaded with JK-2 should be considered for possible bone regeneration.


Assuntos
Regeneração Óssea , Tecidos Suporte , Animais , Adesão Celular , Proliferação de Células , Gelatina , Poliésteres , Coelhos , Engenharia Tecidual
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