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15 pages, 4049 KiB

Open AccessArticle

Green Synthesis of Mesquite-Gum-Stabilized Gold Nanoparticles for Biomedical Applications: Physicochemical Properties and Biocompatibility Assessment

by Ana M. Pinilla-Torres, Celia N. Sanchez-Dominguez, Karla Basilio-Bernabe, Paola Y. Carrion-Garcia, Jorge A. Roacho-Perez, Elsa N. Garza-Treviño, Hugo Gallardo-Blanco and Margarita Sanchez-Dominguez

Polymers 2023, 15(17), 3533; https://doi.org/10.3390/polym15173533 - 24 Aug 2023

Cited by 1 | Viewed by 1158

Abstract

Using cytotoxic reducing and stabilizing agents in the synthesis of gold nanoparticles (AuNPs) limits their use in biomedical applications. One strategy to overcome this problem is using “green” synthesis methodologies using polysaccharides. In the present study, we propose a green methodology for synthetizing [...] Read more.

Using cytotoxic reducing and stabilizing agents in the synthesis of gold nanoparticles (AuNPs) limits their use in biomedical applications. One strategy to overcome this problem is using “green” synthesis methodologies using polysaccharides. In the present study, we propose a green methodology for synthetizing AuNPs with mesquite gum (MG) as a reducing agent and steric stabilizer in Gold(III) chloride trihydrate aqueous solutions to obtain biocompatible nanoparticles that can be used for biomedical applications. Through this method, AuNPs can be produced without using elevated temperatures or pressures. For synthetizing gold nanoparticles coated with mesquite gum (AuNPs@MG), Gold(III) chloride trihydrate was used as a precursor, and mesquite gum was used as a stabilizing and reducing agent. The AuNPs obtained were characterized using UV-Vis spectroscopy, dynamic light scattering, transmission electron microscopy, scanning transmission electron microscopy, and FT-IR spectroscopy. The stability in biological media (phosphate buffer solution), cytotoxicity (MTT assay, hematoxylin, and eosin staining), and hemocompatibility (Hemolysis assay) were measured at different concentrations and exposure times. The results showed the successful synthesis of AuNPs@MG with sizes ranging from 3 to 30 nm and a zeta potential of −31 mV. The AuNPs@MG showed good colloidal stability in PBS (pH 7.4) for up to 24 h. Finally, cytotoxicity assays showed no changes in cell metabolism or cell morphology. These results suggest that these gold nanoparticles have potential biomedical applications because of their low cytotoxicity and hemotoxicity and improved stability at a physiological pH. Full article

(This article belongs to the Special Issue Applications of Biocompatible and Biodegradable Polymers and Their Composites)

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18 pages, 6778 KiB

Open AccessArticle

Effect of Reduction Methods on the Properties of Composite Films of Bacterial Cellulose-Silver Nanoparticles

by Ratchanon Jenkhongkarn and Muenduen Phisalaphong

Polymers 2023, 15(14), 2996; https://doi.org/10.3390/polym15142996 - 10 Jul 2023

Cited by 3 | Viewed by 1231

Abstract

Composite films of bacterial cellulose-silver nanoparticles (BC-Ag) were prepared by different methods of in situ reduction of silver ions, using sodium hydroxide, ascorbic acid, chitosan, and UV irradiation. The effects of the reduction methods on their properties were investigated. The chitosan-reduced composite exhibited [...] Read more.

Composite films of bacterial cellulose-silver nanoparticles (BC-Ag) were prepared by different methods of in situ reduction of silver ions, using sodium hydroxide, ascorbic acid, chitosan, and UV irradiation. The effects of the reduction methods on their properties were investigated. The chitosan-reduced composite exhibited dispersed silver nanoparticles (AgNPs) within the nanocellulose matrix with the smallest size, while the ascorbic-reduced composite displayed the largest size. The incorporation of AgNPs tended to reduce the crystallinity of the composites, except for the ascorbic-reduced composite, which exhibited an increase in crystallinity. Mechanical testing revealed that the ascorbic-reduced composite had the highest Young’s modulus of 8960 MPa, whereas the UV-reduced composite had the highest tensile strength and elongation at break. Thermal analysis of BC-Ag composites indicated similar glass transition temperature and decomposition profiles to BC, with additional weight-loss steps at high temperatures. The sodium hydroxide-reduced composite demonstrated the highest electrical conductivity of 1.1 × 10⁻⁷ S/cm. Water absorption capacity was reduced by the incorporation of AgNPs, except for the chitosan-reduced composite, which showed an enhanced water absorption capacity of 344%. All BC-Ag composites displayed very strong antibacterial activities against Staphylococcus aureus and Escherichia coli. These results also highlight the potential uses of BC-Ag composites for various applications. Full article

(This article belongs to the Special Issue Applications of Biocompatible and Biodegradable Polymers and Their Composites)

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13 pages, 3523 KiB

Open AccessArticle

Human Umbilical Vein Endothelial Cells Form a Network on a Hyaluronic Acid/Gelatin Composite Hydrogel Moderately Crosslinked and Degraded by Hydrogen Peroxide

by Kelum Chamara Manoj Lakmal Elvitigala, Wildan Mubarok and Shinji Sakai

Polymers 2022, 14(22), 5034; https://doi.org/10.3390/polym14225034 - 20 Nov 2022

Cited by 2 | Viewed by 1655

Abstract

The study of the capillary-like network formation of human umbilical vein endothelial cells (HUVECs) in vitro is important for understanding the factors that promote or inhibit angiogenesis. Here, we report the behavior of HUVECs on the composite hydrogels containing hyaluronic acid (HA) and [...] Read more.

The study of the capillary-like network formation of human umbilical vein endothelial cells (HUVECs) in vitro is important for understanding the factors that promote or inhibit angiogenesis. Here, we report the behavior of HUVECs on the composite hydrogels containing hyaluronic acid (HA) and gelatin with different degrees of degradation, inducing the different physicochemical properties of the hydrogels. The hydrogels were obtained through horseradish peroxidase (HRP)-catalyzed hydrogelation consuming hydrogen peroxide (H₂O₂, 16 ppm) supplied from the air, and the degradation degree was tuned by altering the exposure time to the air. The HUVECs on the composite hydrogel with intermediate stiffness (1.2 kPa) obtained through 120 min of the exposure were more elongated than those on the soft (0.4 kPa) and the stiff (2.4 kPa) composite hydrogels obtained through 15 min and 60 min of the exposure, respectively. In addition, HUVECs formed a capillary-like network only on the stiff composite hydrogel although those on the hydrogels with comparable stiffness but containing gelatin alone or alginate instead of HA did not form the network. These results show that the HA/gelatin composite hydrogels obtained through the H₂O₂-mediated crosslinking and degradation could be a tool for studies using HUVECs to understand the promotion and inhibition of angiogenesis. Full article

(This article belongs to the Special Issue Applications of Biocompatible and Biodegradable Polymers and Their Composites)

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11 pages, 1561 KiB

Open AccessArticle

Lung Extracellular Matrix Hydrogels-Derived Vesicles Contribute to Epithelial Lung Repair

by Anna Ulldemolins, Alicia Jurado, Carolina Herranz-Diez, Núria Gavara, Jorge Otero, Ramon Farré and Isaac Almendros

Polymers 2022, 14(22), 4907; https://doi.org/10.3390/polym14224907 - 14 Nov 2022

Cited by 2 | Viewed by 1557

Abstract

The use of physiomimetic decellularized extracellular matrix-derived hydrogels is attracting interest since they can modulate the therapeutic capacity of numerous cell types, including mesenchymal stromal cells (MSCs). Remarkably, extracellular vesicles (EVs) derived from MSCs display similar functions as their parental cells, mitigating tissue [...] Read more.

The use of physiomimetic decellularized extracellular matrix-derived hydrogels is attracting interest since they can modulate the therapeutic capacity of numerous cell types, including mesenchymal stromal cells (MSCs). Remarkably, extracellular vesicles (EVs) derived from MSCs display similar functions as their parental cells, mitigating tissue damage in lung diseases. However, recent data have shown that ECM-derived hydrogels could release other resident vesicles similar to EVs. Here, we aim to better understand the contribution of EVs and ECM-vesicles released from MSCs and/or lung-derived hydrogel (L-HG) in lung repair by using an in vitro lung injury model. L-HG derived-vesicles and MSCs EVs cultured either in L-HG or conventional plates were isolated and characterized. The therapeutic capacity of vesicles obtained from each experimental condition was tested by using an alveolar epithelial wound-healing assay. The number of ECM-vesicles released from acellular L-HG was 10-fold greater than EVs from conventional MSCs cell culture revealing that L-HG is an important source of bioactive vesicles. MSCs-derived EVs and L-HG vesicles have similar therapeutic capacity in lung repair. However, when wound closure rate was normalized by total proteins, the MSCs-derived EVs shows higher therapeutic potential to those released by L-HG. The EVs released from L-HG must be considered when HG is used as substrate for cell culture and EVs isolation. Full article

(This article belongs to the Special Issue Applications of Biocompatible and Biodegradable Polymers and Their Composites)

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13 pages, 3491 KiB

Open AccessArticle

Towards a Whole Sample Imaging Approach Using Diffusion Tensor Imaging to Examine the Foreign Body Response to Explanted Medical Devices

by Ruth E. Levey, Brooke Tornifoglio, Alan J. Stone, Christian Kerskens, Scott T. Robinson, Fergal B. Coulter, Robert Bagnall, Raymond O’Connor, Eimear B. Dolan, Peter Dockery, Gabriella Bellavia, Stefania Straino, Francesca Cianfarani, Paul Johnson, Eoin O’Cearbhaill, Caitríona Lally and Garry P. Duffy

Polymers 2022, 14(22), 4819; https://doi.org/10.3390/polym14224819 - 09 Nov 2022

Viewed by 1534

Abstract

Analysing the composition and organisation of the fibrous capsule formed as a result of the Foreign Body Response (FBR) to medical devices, is imperative for medical device improvement and biocompatibility. Typically, analysis is performed using histological techniques which often involve random sampling strategies. [...] Read more.

Analysing the composition and organisation of the fibrous capsule formed as a result of the Foreign Body Response (FBR) to medical devices, is imperative for medical device improvement and biocompatibility. Typically, analysis is performed using histological techniques which often involve random sampling strategies. This method is excellent for acquiring representative values but can miss the unique spatial distribution of features in 3D, especially when analysing devices used in large animal studies. To overcome this limitation, we demonstrate a non-destructive method for high-resolution large sample imaging of the fibrous capsule surrounding human-sized implanted devices using diffusion tensor imaging (DTI). In this study we analyse the fibrous capsule surrounding two unique macroencapsulation devices that have been implanted in a porcine model for 21 days. DTI is used for 3D visualisation of the microstructural organisation and validated using the standard means of fibrous capsule investigation; histological analysis and qualitative micro computed tomography (microCT) and scanning electron microscopy (SEM) imaging. DTI demonstrated the ability to distinguish microstructural differences in the fibrous capsules surrounding two macroencapsulation devices made from different materials and with different surface topographies. DTI-derived metrics yielded insight into the microstructural organisation of both capsules which was corroborated by microCT, SEM and histology. The non-invasive characterisation of the integration of implants in the body has the potential to positively influence analysis methods in pre-clinical studies and accelerate the clinical translation of novel implantable devices. Full article

(This article belongs to the Special Issue Applications of Biocompatible and Biodegradable Polymers and Their Composites)

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14 pages, 3553 KiB

Open AccessArticle

Polybutylene Succinate Processing and Evaluation as a Micro Fibrous Graft for Tissue Engineering Applications

by Giovanni Carlo Miceli, Fabio Salvatore Palumbo, Francesco Paolo Bonomo, Massimiliano Zingales and Mariano Licciardi

Polymers 2022, 14(21), 4486; https://doi.org/10.3390/polym14214486 - 23 Oct 2022

Cited by 5 | Viewed by 1798

Abstract

A microfibrous tubular scaffold has been designed and fabricated by electrospinning using poly (1,4-butylene succinate) as biocompatible and biodegradable material. The scaffold morphology was optimized as a small diameter and micro-porous conduit, able to foster cell integration, adhesion, and growth while avoiding cell [...] Read more.

A microfibrous tubular scaffold has been designed and fabricated by electrospinning using poly (1,4-butylene succinate) as biocompatible and biodegradable material. The scaffold morphology was optimized as a small diameter and micro-porous conduit, able to foster cell integration, adhesion, and growth while avoiding cell infiltration through the graft’s wall. Scaffold morphology and mechanical properties were explored and compared to those of native conduits. Scaffolds were then seeded with adult normal human dermal fibroblasts to evaluate cytocompatibility in vitro. Haemolytic effect was evaluated upon incubation with diluted whole blood. The scaffold showed no delamination, and mechanical properties were in the physiological range for tubular conduits: elastic modulus (17.5 ± 1.6 MPa), ultimate tensile stress (3.95 ± 0.17 MPa), strain to failure (57 ± 4.5%) and suture retention force (2.65 ± 0.32 N). The shown degradation profile allows the graft to provide initial mechanical support and functionality while being colonized and then replaced by the host cells. This combination of features might represent a step toward future research on PBS as a biomaterial to produce scaffolds that provide structure and function over time and support host cell remodelling. Full article

(This article belongs to the Special Issue Applications of Biocompatible and Biodegradable Polymers and Their Composites)

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17 pages, 4012 KiB

Open AccessArticle

Composite Coatings of Chitosan and Silver Nanoparticles Obtained by Galvanic Deposition for Orthopedic Implants

by C. Zanca, S. Carbone, B. Patella, F. Lopresti, G. Aiello, V. Brucato, F. Carfì Pavia, V. La Carrubba and R. Inguanta

Polymers 2022, 14(18), 3915; https://doi.org/10.3390/polym14183915 - 19 Sep 2022

Cited by 6 | Viewed by 2393

Abstract

In this work, composite coatings of chitosan and silver nanoparticles were presented as an antibacterial coating for orthopedic implants. Coatings were deposited on AISI 304L using the galvanic deposition method. In galvanic deposition, the difference of the electrochemical redox potential between two metals [...] Read more.

In this work, composite coatings of chitosan and silver nanoparticles were presented as an antibacterial coating for orthopedic implants. Coatings were deposited on AISI 304L using the galvanic deposition method. In galvanic deposition, the difference of the electrochemical redox potential between two metals (the substrate and a sacrificial anode) has the pivotal role in the process. In the coupling of these two metals a spontaneous redox reaction occurs and thus no external power supply is necessary. Using this process, a uniform deposition on the exposed area and a good adherence of the composite coating on the metallic substrate were achieved. Physical-chemical characterizations were carried out to evaluate morphology, chemical composition, and the presence of silver nanoparticles. These characterizations have shown the deposition of coatings with homogenous and porous surface structures with silver nanoparticles incorporated and distributed into the polymeric matrix. Corrosion tests were also carried out in a simulated body fluid at 37 °C in order to simulate the same physiological conditions. Corrosion potential and corrosion current density were obtained from the polarization curves by Tafel extrapolation. The results show an improvement in protection against corrosion phenomena compared to bare AISI 304L. Furthermore, the ability of the coating to release the Ag⁺ was evaluated in the simulated body fluid at 37 °C and it was found that the release mechanism switches from anomalous to diffusion controlled after 3 h. Full article

(This article belongs to the Special Issue Applications of Biocompatible and Biodegradable Polymers and Their Composites)

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13 pages, 3912 KiB

Open AccessArticle

The Use of Waste Hazelnut Shells as a Reinforcement in the Development of Green Biocomposites

by Manuela Ceraulo, Francesco Paolo La Mantia, Maria Chiara Mistretta and Vincenzo Titone

Polymers 2022, 14(11), 2151; https://doi.org/10.3390/polym14112151 - 25 May 2022

Cited by 7 | Viewed by 2086

Abstract

Biodegradable Mater-Bi (MB) composites reinforced with hazelnut shell (HS) powder were prepared in a co-rotating twin-screw extruder followed by compression molding and injection molding. The effects of reinforcement on the morphology, static and dynamic mechanical properties, and thermal and rheological properties of MB/HS [...] Read more.

Biodegradable Mater-Bi (MB) composites reinforced with hazelnut shell (HS) powder were prepared in a co-rotating twin-screw extruder followed by compression molding and injection molding. The effects of reinforcement on the morphology, static and dynamic mechanical properties, and thermal and rheological properties of MB/HS biocomposites were studied. Rheological tests showed that the incorporation of HS significantly increased the viscosity of composites with non-Newtonian behavior at low frequencies. On the other hand, a scanning electron microscope (SEM) examination revealed poor interfacial adhesion between the matrix and the filler. The thermal property results indicated that HS could act as a nucleating agent to promote the crystallization properties of biocomposites. Furthermore, the experimental results indicated that the addition of HS led to a significant improvement in the thermomechanical stability of the composites. This paper demonstrates that the incorporation of a low-cost waste product, such as hazelnut shells, is a practical way to produce low-cost biocomposites with good properties. With a content of HS of 10%, a remarkable improvement in the elastic modulus and impact strength was observed in both compression and injection-molded samples. With a higher content of HS, however, the processability in injection molding was strongly worsened. Full article

(This article belongs to the Special Issue Applications of Biocompatible and Biodegradable Polymers and Their Composites)

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9 pages, 2509 KiB

Open AccessArticle

Artificial Synapses Based on Bovine Milk Biopolymer Electric-Double-Layer Transistors

by Sung-Hun Kim and Won-Ju Cho

Polymers 2022, 14(7), 1372; https://doi.org/10.3390/polym14071372 - 28 Mar 2022

Cited by 6 | Viewed by 2075

Abstract

With the growing demand for bio- and eco-friendly artificial synapses, we propose a novel synaptic transistor using natural bovine-milk-based biocompatible polymers as an electrical double layer (EDL). A method for forming an EDL membrane, which plays a key role in synaptic devices, was [...] Read more.

With the growing demand for bio- and eco-friendly artificial synapses, we propose a novel synaptic transistor using natural bovine-milk-based biocompatible polymers as an electrical double layer (EDL). A method for forming an EDL membrane, which plays a key role in synaptic devices, was established using a milk-based biocompatible polymer. The frequency-dependent capacitance of a milk-based polymer-EDL was evaluated by constructing an EDL capacitor (EDLC) with indium-tin-oxide (ITO) electrode. As a result, a significantly large capacitance (1.48 μF/cm² at 1 Hz) was identified as an EDL effect due to the proton charge of the bovine-milk-based polymer, which is much more superior compared to conventional insulating materials such as SiO₂. Subsequently, by using a milk-based polymer-EDL membrane in the fabrication of electronic synaptic transistors, we successfully implemented important synaptic functions, such as paired-pulse facilitation, dynamic filtering, and synaptic-weight-integration-based logic operations. Therefore, the proposed milk-based biocompatible polymer-EDL membrane offers new opportunities for building eco-friendly and biodegradable artificial synaptic systems. Full article

(This article belongs to the Special Issue Applications of Biocompatible and Biodegradable Polymers and Their Composites)

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21 pages, 7784 KiB

Open AccessArticle

Formulation of Piperine Nanoparticles: In Vitro Breast Cancer Cell Line and In Vivo Evaluation

by Imran Kazmi, Fahad A. Al-Abbasi, Syed Sarim Imam, Muhammad Afzal, Muhammad Shahid Nadeem, Hisham N. Altayb and Sultan Alshehri

Polymers 2022, 14(7), 1349; https://doi.org/10.3390/polym14071349 - 26 Mar 2022

Cited by 9 | Viewed by 2359

Abstract

Piperine (PPN), one of the most investigated phytochemicals, is known to have excellent therapeutic efficacy against a variety of ailments including breast cancer. However, its physicochemical properties such as poor aqueous solubility restrict its clinical application. Therefore, the present investigation was designed to [...] Read more.

Piperine (PPN), one of the most investigated phytochemicals, is known to have excellent therapeutic efficacy against a variety of ailments including breast cancer. However, its physicochemical properties such as poor aqueous solubility restrict its clinical application. Therefore, the present investigation was designed to develop PPN encapsulated lipid polymer hybrid nanoparticles (PPN-LPHNPs) to overcome the limitation. The developed PPN-LPHNPs were optimized by the three-factor, three-level Box–Behnken design (3³-BBD). The optimized PPN-LPHNPs were then evaluated for their drug release profile, cytotoxicity assay against MDA-MB-231 and MCF-7 cells, and gastrointestinal stability as well as colloidal stability. In addition, the optimized PPN-LPHNPs were evaluated for ex vivo intestinal permeation and in vivo pharmacokinetic in albino Wistar rats. As per the results, the optimized PPN-LPHNPs showed a small average particles size of <160 nm with a low (<0.3) polydispersity index, and highly positive surface charge (>+20 mV). PPN-LPHNPs revealed excellent gastrointestinal as well as colloidal stability and sustained release profiles up to 24 h. Furthermore, PPN-LPHNPs revealed excellent cytotoxicity against both MDA-MB-231 and MCF-7 cancer cells compared to the free PPN. Moreover, animal studies revealed that the PPN-LPHNPs exhibited a 6.02- and 4.55-fold higher intestinal permeation and relative oral bioavailability, respectively, in comparison to the conventional PPN suspension. Thus, our developed LPHNPs present a strong potential for improved delivery of PPN. Full article

(This article belongs to the Special Issue Applications of Biocompatible and Biodegradable Polymers and Their Composites)

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20 pages, 4744 KiB

Open AccessArticle

The Influence of Additives and Environment on Biodegradation of PHBV Biocomposites

by Pavel Brdlík, Martin Borůvka, Luboš Běhálek and Petr Lenfeld

Polymers 2022, 14(4), 838; https://doi.org/10.3390/polym14040838 - 21 Feb 2022

Cited by 7 | Viewed by 2861

Abstract

The biodegradation of polyhydroxybutyrate-co-hydroxyvalerate (PHBV) ternary biocomposites containing nature-based plasticizer acetyl tributyl citrate (ATBC), heterogeneous nucleation agents—calcium carbonate (CaCO₃) and spray-dried lignin-coated cellulose nanocrystals (L-CNC)—in vermicomposting, freshwater biotope, and thermophilic composting have been studied. The degree of disintegration, differential scanning calorimetry [...] Read more.

The biodegradation of polyhydroxybutyrate-co-hydroxyvalerate (PHBV) ternary biocomposites containing nature-based plasticizer acetyl tributyl citrate (ATBC), heterogeneous nucleation agents—calcium carbonate (CaCO₃) and spray-dried lignin-coated cellulose nanocrystals (L-CNC)—in vermicomposting, freshwater biotope, and thermophilic composting have been studied. The degree of disintegration, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and the evaluation of surface images taken by scanning electron microscopy (SEM) were conducted for the determination influence of different environments and additives on the biodegradation of PHBV. Furthermore, the method adapted from ISO 14855-1 standard was used for thermophilic composting. It is a method based on the measurement of the amount of carbon dioxide evolved during microbial degradation. The highest biodegradation rate was observed in the thermophilic condition of composting. The biodegradation level of all PHBV-based samples was, after 90 days, higher than 90%. Different mechanisms of degradation and consequently different degradation rate were evaluated in vermicomposting and freshwater biotope. The surface enzymatic degradation, observed during the vermicomposting process, showed slightly higher biodegradation potential than the hydrolytic attack of freshwater biotope. The application of ATBC plasticizers in the PHBV matrix caused an increase in biodegradation rate in all environments. However, the highest biodegradation rate was achieved for ternary PHBV biocomposites containing 10 wt. % of ATBC and 10 wt. % of CaCO₃. A considerable increase in the degree of disintegration was evaluated, even in freshwater biotope. Furthermore, the slight inhibition effect of L-CNC on the biodegradation process of ternary PHBV/ATBC/L-CNC could be stated. Full article

(This article belongs to the Special Issue Applications of Biocompatible and Biodegradable Polymers and Their Composites)

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14 pages, 3839 KiB

Open AccessArticle

Combined Effect of Biopolymer and Fiber Inclusions on Unconfined Compressive Strength of Soft Soil

by Chunhui Chen, Kai Wei, Jiayu Gu, Xiaoyang Huang, Xianyao Dai and Qingbing Liu

Polymers 2022, 14(4), 787; https://doi.org/10.3390/polym14040787 - 17 Feb 2022

Cited by 12 | Viewed by 2354

Abstract

The utilizing of traditional chemical stabilizers could improve soil engineering properties but also results in brittle behavior and causes environmental problems. This study investigates the feasibility of the combined utilization of an ecofriendly biopolymer and fiber inclusions as an alternative to traditional cement [...] Read more.

The utilizing of traditional chemical stabilizers could improve soil engineering properties but also results in brittle behavior and causes environmental problems. This study investigates the feasibility of the combined utilization of an ecofriendly biopolymer and fiber inclusions as an alternative to traditional cement for reinforcing soft soil. A series of unconfined compression tests were conducted to examine the combined effect of the biopolymer and fibers on the stress–strain characteristics, strength improvement, failure pattern, and reinforcement mechanism of soft soil. The results show that the biopolymer associated with fibers has an unconfined compressive strength similar to that of fiber-reinforced soil. However, it then increases with different curing times and conditions, which can be up to 1.5 MPa–2.5 MPa. The combined effect of fibers and the biopolymer is not simply equivalent to the sum of the effects of each individual material. The fiber shows its role instantly after being mixed into soil, whereas the effect of biopolymer gradually appears with sample curing time. The biopolymer plays a dominant role in increasing the peak unconfined compressive strength and brittleness of soil, while the amount of fiber is crucial for reducing soil brittleness and increasing ductility. It is shown that the biopolymer not only contributes to the particle bonding force but also facilitates the reinforcement efficiency of fibers in the soil. The fibers in return assist in reducing the soil brittleness arising from biopolymer cementation and provide residual resistance after post-peak failure. Full article

(This article belongs to the Special Issue Applications of Biocompatible and Biodegradable Polymers and Their Composites)

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18 pages, 4177 KiB

Open AccessArticle

Rheology and Tack Properties of Biodegradable Isodimorphic Poly(butylene succinate)-Ran-Poly(ε-caprolactone) Random Copolyesters and Their Potential Use as Adhesives

by Aleida J. Sandoval, María Mercedes Fernández, María Virginia Candal, Maryam Safari, Antxon Santamaria and Alejandro J. Müller

Polymers 2022, 14(3), 623; https://doi.org/10.3390/polym14030623 - 06 Feb 2022

Cited by 6 | Viewed by 2500

Abstract

The sole effect of the microstructure of biodegradable isodimorphic poly(butylene succinate)-ran-poly(ε-caprolactone) random copolyesters on their rheological properties is investigated. To avoid the effect of molecular weight and temperature, two rheological procedures are considered: the activation energy of flow, E_a, [...] Read more.

The sole effect of the microstructure of biodegradable isodimorphic poly(butylene succinate)-ran-poly(ε-caprolactone) random copolyesters on their rheological properties is investigated. To avoid the effect of molecular weight and temperature, two rheological procedures are considered: the activation energy of flow, E_a, and the phase angle versus complex modulus plots. An unexpected variation of both parameters with copolyester composition is observed, with respective maximum and minimum values for the 50/50 composition. This might be due to the peculiar chain configurations of the copolymers that vary as a function of comonomer distribution within the chains. The same chain configuration variations are responsible for the isodimorphic character of the copolymers in the crystalline state. Tack tests, performed to study the viability of the copolyesters as environmentally friendly hot melt adhesives (HMA), reveal a correlation with rheological results. Tackiness parameters, particularly the energy of adhesion obtained from stress-strain curves during debonding experiments, are enhanced as melt elasticity increases. Based on the carried-out analysis, the link microstructure-rheology-tackiness is established, allowing selecting the best performing HMA sample considering the polymer chemistry of the system. Full article

(This article belongs to the Special Issue Applications of Biocompatible and Biodegradable Polymers and Their Composites)

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11 pages, 854 KiB

Open AccessArticle

Eugenyl-2-Hydroxypropyl Methacrylate-Incorporated Experimental Dental Composite: Degree of Polymerization and In Vitro Cytotoxicity Evaluation

by Abdel-Basit Al-Odayni, Dalal H. Alotaibi, Waseem Sharaf Saeed, Abdullah Al-Kahtani, Ali Assiri, Fahad M. Alkhtani and Ali Alrahlah

Polymers 2022, 14(2), 277; https://doi.org/10.3390/polym14020277 - 11 Jan 2022

Cited by 7 | Viewed by 1773

Abstract

The aim of this study was to evaluate the properties of new dental formulations containing eugenyl-2-hydroxypropyl methacrylate (EgGMA) monomer, as restorative dental material, in terms of their degree of photopolymerization and cytotoxicity. The target model composites (TBEg0, TBEg2.5, and TBEg5) were prepared by [...] Read more.

The aim of this study was to evaluate the properties of new dental formulations containing eugenyl-2-hydroxypropyl methacrylate (EgGMA) monomer, as restorative dental material, in terms of their degree of photopolymerization and cytotoxicity. The target model composites (TBEg0, TBEg2.5, and TBEg5) were prepared by mixing 35% organic matrix (TEGDMA/BisGMA (50/50 wt%) of which 0, 2.5, and 5 wt%, respectively, were replaced with EgGMA monomer) with 65% filler (silanized hydroxyapatite (HA)/zinc oxide (ZnO₂), 4:3 by weight). The vinylic double-bond conversion (DC) after light-curing was studied using Fourier transform infrared technique whereas cell viability was in vitro tested using primary human gingival fibroblasts cells over 7 days by means of AlamarBlue colorimetric assay. The obtained data were statistically analyzed using ANOVA and Tukey post-hoc tests. The results revealed no significant difference in DC between TBEg2.5 (66.49%) and control (TBEg0; 68.74%), whereas both differ significantly with TBEg5, likely due to the inhibitory effect of eugenol moiety at high concentration. The cell viability test indicated that all the composites are biocompatible. No significant difference was counted between TBEg2.5 and TBEg5, however, both differed significantly from the control (TBEg0). Thus, even though its apparent negative effect on polymerization, EgGMA is potentially safer than bisphenol-derived monomers. Such potential properties may encourage further investigations on term of EgGMA amount optimization, compatibility with other dental resins, and antimicrobial activity. Full article

(This article belongs to the Special Issue Applications of Biocompatible and Biodegradable Polymers and Their Composites)

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Review

Jump to: Research

28 pages, 6119 KiB

Open AccessReview

A Review on Bast-Fibre-Reinforced Hybrid Composites and Their Applications

by Teboho Clement Mokhena, Asanda Mtibe, Thabang Hendrica Mokhothu, Mokgaotsa Jonas Mochane and Maya Jacob John

Polymers 2023, 15(16), 3414; https://doi.org/10.3390/polym15163414 - 15 Aug 2023

Cited by 3 | Viewed by 1424

Abstract

The development of eco-friendly products to protect the environment has become a topical subject in the research and industrial communities. This is a result of strict environmental regulations necessitating the development of novel strategies to reduce our reliance on petroleum-based products, which exert [...] Read more.

The development of eco-friendly products to protect the environment has become a topical subject in the research and industrial communities. This is a result of strict environmental regulations necessitating the development of novel strategies to reduce our reliance on petroleum-based products, which exert a negative effect on our ecosystem. Bast-fibre-based hybrids have been extensively studied for various applications due to their eco-friendliness and cost effectiveness. There is a very limited number of review articles covering the properties and preparation of bast-fibre-based hybrid composites. This review is designed to provide an overview of the preparation and application of bast-fibre-based hybrid composites. It covers the thermal properties, mechanical properties, moisture absorption and flame-retardant properties of bast hybrid composites. This review not only summarises recent advances on the use and preparation of bast hybrid composites, it also presents a future outlook. Full article

(This article belongs to the Special Issue Applications of Biocompatible and Biodegradable Polymers and Their Composites)

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29 pages, 54268 KiB

Open AccessReview

Poly-l-Lactic Acid (PLLA)-Based Biomaterials for Regenerative Medicine: A Review on Processing and Applications

by Elisa Capuana, Francesco Lopresti, Manuela Ceraulo and Vincenzo La Carrubba

Polymers 2022, 14(6), 1153; https://doi.org/10.3390/polym14061153 - 14 Mar 2022

Cited by 78 | Viewed by 13439

Abstract

Synthetic biopolymers are effective cues to replace damaged tissue in the tissue engineering (TE) field, both for in vitro and in vivo application. Among them, poly-l-lactic acid (PLLA) has been highlighted as a biomaterial with tunable mechanical properties and biodegradability that [...] Read more.

Synthetic biopolymers are effective cues to replace damaged tissue in the tissue engineering (TE) field, both for in vitro and in vivo application. Among them, poly-l-lactic acid (PLLA) has been highlighted as a biomaterial with tunable mechanical properties and biodegradability that allows for the fabrication of porous scaffolds with different micro/nanostructures via various approaches. In this review, we discuss the structure of PLLA, its main properties, and the most recent advances in overcoming its hydrophobic, synthetic nature, which limits biological signaling and protein absorption. With this aim, PLLA-based scaffolds can be exposed to surface modification or combined with other biomaterials, such as natural or synthetic polymers and bioceramics. Further, various fabrication technologies, such as phase separation, electrospinning, and 3D printing, of PLLA-based scaffolds are scrutinized along with the in vitro and in vivo applications employed in various tissue repair strategies. Overall, this review focuses on the properties and applications of PLLA in the TE field, finally affording an insight into future directions and challenges to address an effective improvement of scaffold properties. Full article

(This article belongs to the Special Issue Applications of Biocompatible and Biodegradable Polymers and Their Composites)

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