Macromol

Electrospinning is a simple and versatile method to generate nanofibers. Remarkable progress has been made in the development of the electrospinning process. The production of nanofibers is affected by many parameters, which influence the final material properties. Electrospun fibers have a wide range of applications, such as energy storage devices and biomedical scaffolds. Among polymers chosen for biological scaffolds, such as PLA or collagen, polyacrylonitrile (PAN) has received increasing interest in recent years due to its excellent characteristics, such as spinnability, biocompatibility, and commercial viability, opening the way to new applications in the biotechnological field. This paper provides an overview of the electrospinning process of a large range of polymers of interest for biomedical applications, including PLA and PEO. It covers the main parameters and operation modes that affect nanofiber fabrication. Their biological applications are reviewed. A focus is placed on PAN fiber formation, functionalization, and application as scaffolds to allow cell growth. Overall, nanofiber scaffolds appear to be powerful tools in medical applications that need controlled cell culture. Full article

This study aims to confer autohesive strength to polyethylene (PE) plates by swelling the grafted layers, which were formed on the PE plates grafted with alkyl (meth)acrylate monomers, with 1,4-dioxane, and subsequently heat-pressing them. For the methyl methacrylate (MMA)-grafted PE (PE-g-PMMA) plates, the location of grafting was restricted to the outer surface region and the grafted layer with higher densities of grafted PMMA chains was composed. When the grafted PE plates were immersed in 1,4-dioxane, and then heat-pressed while applying the load, autohesion was developed. The substrate failure was observed for the PE-g-PMMA plates and the grafted amount at which the substrate failure was observed decreased with the procedures that decreased the methanol concentration of the solvent, the MMA concentration, the grafting temperature, and the heat-press temperature, and/or increased the load. The lowest grafted amount of 45 μmol/cm² for the substrate failure was obtained under the conditions where the PE-g-PMMA plate prepared at 0.75 M and 60 °C in a 70 vol% aqueous methanol solution was heat-pressed at 60 °C while applying the load of 2.0 kg/cm². The swelling of the grafted layers with 1,4-dioxane considerably contributed to the development of autohesion, bringing the inter-diffusion of grafted PMMA chains and coincident entanglement of grafted PMMA chains during the heat-pressing. The fact that the substrate failure occurred indicates that an autohesive strength higher than the ultimate strength of the used PE plate was obtained. Our approach provides a novel procedure to develop the water-resistant autohesion of PE plates. Full article

Tissue engineering and regenerative medicine have emerged as innovative approaches to enhance clinical outcomes by addressing tissue lesions and degenerations that can significantly impair organ function. Since human tissues have limited regenerative capacity, the field of regenerative medicine aims to restore damaged tissues and their functionalities. Recent decades have witnessed remarkable progress in materials science, tissue engineering, and medicine, leading to the development of regenerative engineering. This interdisciplinary field has revolutionized the production of artificial matrices, enabling the design of anatomically accurate structures with enhanced biocompatibility, bioabsorption, and cell adhesion. Among the techniques utilized for fabricating cellular scaffolds, the electrospinning of fibers stands out as an ideal approach due to its ability to mimic the characteristics of the extracellular matrix (ECM). Electrospun scaffolds exhibit distinct advantages, including a high surface area-to-volume ratio, exceptional porosity, uniformity, compositional diversity, structural flexibility, and the ease of functionalization with bioactive molecules for controlled release. These versatile properties allow for the creation of nanofiber scaffolds that closely resemble the architecture of the ECM. Consequently, they facilitate the transport of nutrients and oxygen to cells as well as the incorporation of growth factors to stimulate cell growth. These advancements open up a wide range of applications in the field of regenerative medicine. Full article

Polyphenols have attracted attention for their anti-inflammatory, antidiabetic, and anticancer properties. Due to the antioxidant and anti-inflammatory potential of these molecules, they are also proposed as a potential therapeutic tool to prevent complications of cancer and decrease the secondary effects of conventional chemotherapeutic drugs. Nonetheless, polyphenols such as flavonoids and phenolic acids have low bioavailability, as they are highly metabolized. Thus, administration strategies have been developed to enhance the anticancer properties of polyphenols. Most of these strategies involve different encapsulation techniques, such as nanoencapsulation, nanoemulsion, and the use of other polymeric matrixes. These techniques can increase the activity of these compounds after going through the gastrointestinal process and improve their solubility in an aqueous medium. This review comprises recent studies regarding encapsulation techniques to enhance the bioactivity of polyphenols against cancer and their current state in clinical studies. Overall, micro- and nanoencapsulation techniques with different polymers enhanced the anticancer properties of polyphenols by inhibiting tumor growth, modulating the expression of genes related to metastasis and angiogenesis, decreasing the expression of pro-inflammatory biomarkers. Full article

This review considers the recent investigations in the scope of biodegradability of synthetic polymers, spanning polyethylene (PE), polypropylene (PP), and their corresponding composites, with a focus on the influence of oxo-additives (mostly transition metal salts). The types of oxo-additives and the mechanisms of oxidation acceleration are discussed. Furthermore, the influence of oxo-additives on both physicochemical and biological stages of degradation is evaluated (laboratory and field experiments with microorganisms/fungi action) with recent standards suggested for degradation estimation. Comparisons of the metal salts are given with respect to catalysis, as well as the synergetic influence of additives. The additives presented on the commercial market are also discussed. Full article

In this work, a simple and environmentally friendly process combining low pressure (vacuum) and mechanical compression is proposed to convert recycled polypropylene (PP) foams (28 kg/m³) into low density foams (90–131 kg/m³) having negative tensile and compressive Poisson’s ratios (NPR). The main objective of the work was to determine the effect of processing conditions (vacuum time, temperature and mechanical pressure). Based on the optimized conditions, the tensile Poisson’s ratio of the resulting auxetic foams reached −1.50, while the minimum compressive Poisson’s ratio was −0.32 for the same sample. The foam structure was characterized via morphological analysis (SEM) to determine any changes related to the treatment applied. Finally, the tensile and compressive properties (Young’s modulus, strain energy, energy dissipation and damping capacity) are also presented and discussed. It was observed that the mechanical properties of the resulting auxetic foams were improved compared to the original PP foam (PP-O) for all tensile properties in terms of modulus (19.9 to 59.8 kPa), strength (0.298 to 1.43 kPa) elongation at break (28 to 77%), energy dissipation (14.4 to 56.3 mJ/cm³) and damping capacity (12 to 19%). Nevertheless, improvements were also observed under compression in terms of the energy dissipation (1.6 to 3.6 mJ/cm³) and the damping capacity (13 to 19%). These auxetic foams can find applications in sport and military protective equipment, as well as any energy mitigation system. Full article

In this study, we evaluated the susceptibility of Alphitobius diaperinus larvae and adults to saline extract (SE), lectin-rich fraction (FR), and isolated lectin (MvRL) from Microgramma vacciniifolia rhizomes. To determine immediate effects, larvae and adults were exposed to SE (10.5 mg/mL), FR (7.5 mg/mL), or MvRL (1.0 mg/mL) for 48 h. Live insects were evaluated for acetylcholinesterase (AChE) activity. The delayed effects of SE (10.5 mg/mL), FR (7.5 mg/mL), and MvRL (0.2 and 0.4 mg/mL) were checked by incubating the adults for 16 days with a diet containing the preparations. In vitro effects on gut digestive enzymes were investigated. All preparations showed immediate larvicidal effect but had no effect on adult survival. Extracts from FR-treated larvae showed higher AChE activity than control insects. In the delayed effect assay, the adults lost biomass after consuming SE and FR. FR was the most effective inhibitory agent of trypsin-like and amylase activities (88% and 65% inhibition, respectively). All preparations inhibited endoglucanase activity in 94–98%, while SE and FR inhibited exoglucanase activity in 93.2 and 94.1%, respectively. In conclusion, M. vacciniifolia rhizomes contain compounds (including MvRL) that affect the survival and physiology of A. diaperinus, acting as potential natural insecticides for controlling this pest. Full article

The use of biodegradable polymers in tissue engineering has been widely researched due to their ability to degrade and release their components in a controlled manner, allowing for the potential regeneration of tissues. Melt blending is a common method for controlling the degradation rate of these polymers, which involves combining these materials in a molten state to create a homogenous mixture with tailored properties. In this study, polycaprolactone (PCL) was melt blended with hydrophilic poly (ethylene oxide) (PEO) of different molecular weights to assess its effect on PCL material performance. Hydrolytic degradation, thermal and viscoelastic properties, and surface hydrophilicity were performed to contrast the properties of the blends. DSC, DMA, and FTIR were performed on selected degraded PCL/PEO specimens following mass loss studies. The results showed that adding PEO to PCL reduced its melt viscosity-torque and melt temperature while increasing its hydrophilicity, optimizing PCL/PEO blend for soft tissue engineering applications and could contribute to the development of more effective and biocompatible materials for soft tissue regeneration. Full article

The degradation patterns of bacterial poly-3-hydroxybutyrate (PHB) in chloroform solution under the action of thionyl chloride in the presence of zinc chloride were studied. When 2.5.mol of zinc chloride and 100 mmol of thionyl chloride were introduced into the solution of 25 mmol PHB, a decrease in the molecular weight of the polymer was observed. During the reaction, a relatively rapid decrease in the molecular weight of the polymer was noted in the first hour of the experiment; thus, the values of the weight-average molecular weight decreased from 840 kDa to 483, 167, 58.6, and 16.7 kDa after 1, 5, 24, and 96 h of the experiment, respectively. The polydispersity also gradually decreased from 2.69 at the beginning to 1.92 at the end of the experiment. Oligomers of PHB containing 3-chlorobutyric acid and 3-hydroxybutyryl chloride residues at the O and C ends of the polymer chain, respectively, were obtained. The results confirm the ability of thionyl chloride to interact with aliphatic esters in the presence of zinc compounds, and demonstrate the possibility of using this reaction to produce oligomeric derivatives of polyesters bearing chloralkyl and acid chloride functional groups. Full article

Nanocellulose can be obtained from low-cost sources and has been extensively studied in the last decades due to its biodegradability, biocompatibility, low weight, large specific surface area, and good mechanical and optical properties. The nanocellulose properties palette can be greatly expanded by incorporating different metals, metal oxides or carbon nanomaterials, with the formation of multifunctional hybrids. Nanocellulose–nanocarbon hybrids are emerging nanomaterials that can respond to many current challenges in areas such as water purification, energy storage and conversion, or biomedicine for drug delivery, tissue engineering, antitumor and antimicrobial therapies, and many others. Although nanocellulose–nanodiamonds hybrids are still in their infancy, these nanomaterials are extremely promising for applications requiring good thermal conductivity and mechanical strength along with optical transparency. A strong increase in the thermal conductivity of a nanocellulose film of about 150 times was obtained after the addition of 90 wt% single-crystal nanodiamonds and a 70% increase in the Young’s modulus of nanocellulose films was produced by the addition of 5 wt% nanodiamonds. Therefore, in this review, data related to the manufacturing routes, main properties, and applications of nanocellulose–nanodiamonds hybrids are presented and discussed. This review paves the way for new methods and procedures to obtain nanocellulose–nanodiamonds hybrids better adapted to practical needs. Full article

Nowadays, sustainable and biodegradable bioplastics are gaining significant attention due to resource depletion and plastic pollution. An increasing number of environmentally friendly plastics are being introduced to the market with the aim of addressing these concerns. However, many final products still contain additives or mix non-biodegradable polymers to ensure minimum performance, which often undermines their ecological footprint. Moreover, there is a lack of knowledge about all stages of biodegradation and their accuracy in classifying products as biodegradable. Therefore, this review provides an overview of biodegradable polymers, elucidating the steps and mechanisms of polymer biodegradation. We also caution readers about the growing marketing practice of “greenwashing” where companies or organizations adopt green marketing strategies to label products with more environmental benefits than they have. Furthermore, we present the main standards for evaluating biodegradation, tools, and tests capable of measuring the biodegradation process. Finally, we suggest strategies and perspectives involving concepts of recycling and the circularity of polymers to make them more environmentally friendly and sustainable. After all, “throwing away” plastics should not be an option because there is no outside when there is only one planet. Full article

Dendrimers are increasingly being studied in the context of encapsulation. Many potential applications of dendrimers are based on their properties. They are used in drug delivery systems, cosmetics, food and chemistry. This review is first devoted to different synthesis approaches for dendrimers and to their ability to encapsulate active molecules. Their applications in different fields, as well as their cytotoxicity, are then detailed. To conclude this review, the main works on the interaction of dendrimers with the stratum corneum (SC) are also presented. Full article

A large bone defect is defined as a defect that exceeds the regenerative capacity of the bone. Nowadays, autologous bone grafting is still the gold standard treatment. In this study, a hybrid bone tissue engineering scaffold (BTE) was designed with biocompatibility, biodegradability and adequate mechanical strength as the primary objectives. Chitosan (CS) is a biocompatible and biodegradable polymer that can be used in a wide range of applications in bone tissue engineering. Hydroxyapatite (HAp) and fluorapatite (FAp) have the potential to improve the mechanical properties of CS. In the present work, different volumes of acetic acid (AA) and different ratios of HAp and FAp scaffolds were prepared and UV cross-linked to form a 3D structure. The properties of the scaffolds were characterised by scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, swelling studies and compression testing. The cytotoxicity result was obtained by the MTT assay. The degradation rate was tested by weight loss after the scaffold was immersed in SBF. The results showed that a crosslinked structure was formed and that bonding occurred between different materials within the scaffold. Additionally, the scaffolds not only provided sufficient mechanical strength but were also cytocompatibility, depending on their composition. The scaffolds were degraded gradually within a 6-to-8-week testing period, which closely matches bone regeneration rates, indicating their potential in the BTE field. Full article

The biggest challenge for scientists is to create an ideal wound dressing that should be non-toxic, biocompatible, and biodegradable, providing optimal conditions for the most effective regeneration process. Biomaterials loaded with plant-derived compounds show better biocompatibility and biological properties, ensuring a faster tissue repair process. In order to develop membranes with good mechanical properties and anti-bacterial properties, the objective of this work describes the synthesis of a chitosan-based membrane added with olive leaf extract as an active principle with potential for topical application. The material developed was characterized in terms of morphology, physical, chemical, and mechanical properties, and the anti-bacterial capacity of the membranes. The results indicated that the developed membrane has good potential for use as a wound dressing, as it presented mechanical properties (30.17 ± 8.73 MPa) and fluid draining capacity (29.31 ± 1.65 g·m⁻²·h⁻¹) adequacy. In addition, the antimicrobial activity analysis revealed the active membrane potential against E. coli and S. aureus reaching 9.9 mm and 9.1 mm, respectively, in inhibition zones, the most common bacteria in skin wounds. Therefore, all the results indicate that the developed membrane presents viable characteristics for the use of wound dressing. Full article

Using natural materials as reinforcements for polypropylene to alter composite properties and cost is a well-known approach. Often, wood particles are used for that. These give reasonable reinforcement, but are also sought after by other industries, e.g., for energy production, and may also not be available everywhere. Therefore, the aim of this work was to investigate cherry pit particles as an alternative material for polypropylene reinforcement. Cherry pits originate as a by-product from fruit processing and have not been utilized until now as reinforcement. Cherry pit particles were produced by milling the pits, and afterwards composites were produced by compounding and injection molding. Mechanical properties and melt flow were investigated. We found some reinforcement effect, but to a lesser extent than wood particles. The cherry pit particles contain some fatty acid components, which reduce tensile properties and increase the melt flow rate of the composites. For future applications, methods for reducing these fatty acids to improve reinforcement capabilities should be investigated. Full article

Lectins (carbohydrate-binding proteins) are able to distinguish different patterns of glycosylation on cell surfaces. This study investigated the effects of lectins from Alpinia purpurata inflorescence (ApuL) and Schinus terebinthifolia leaf (SteLL) on the viability of human leukemia cells (K562, chronic myeloid leukemia; JURKAT, acute lymphoblastic leukemia) and mesenchymal stem cells (MSCs) from human umbilical cords. In addition, possible immunomodulatory effects of ApuL and SteLL on MSCs were assessed by determining cytokine levels in cultures. ApuL reduced the viability of JURKAT cells (IC₅₀: 12.5 μg/mL), inducing both apoptosis and necrosis. For K562 cells, ApuL at 50 µg/mL caused a decrease in viability, but of only 8.8%. Conversely, SteLL exerted a cytotoxic effect on K562 (IC₅₀: 6.0 μg/mL), inducing apoptosis, while it was not cytotoxic to JURKAT. ApuL and SteLL (0.19–100 μg/mL) did not decrease MSCs viability. Treatment with ApuL strongly suppressed (99.5% reduction) the release of IL-6 by MSCs. SteLL also reduced the levels of this cytokine in culture supernatant. In conclusion, ApuL and SteLL showed potential to reduce the viability of leukemia cells, as well as immunomodulatory effect on MSCs without being toxic to them. These biological properties can be explored biomedically and biotechnologically in the future. Full article

The food industry produces an exorbitant amount of solid waste of petrochemical origin as a result of the increase in the development of new products. Natural polymers are an alternative to this theme; however, their development with adequate properties is a challenge. The union of different polymers in the synthesis of packaging is usually carried out to improve these properties. The combination of agar-agar and chitosan biopolymers show particular advantages through hydrogen bonds and electrostatic attraction between oppositely charged groups, presenting a promising source of studies for the synthesis of green packaging. When combined with natural extracts with active properties, these polymers allow an increase in the microbiological stability of foods associated with lower chemical preservative content and greater environmental sustainability. Full article

Heat-resistant polymers with an intense, visible photoluminescence (PL) functionality are presented. A polybenzoxazole (PBO) containing hexafluoroisopropylidene (HFIP) side groups exhibited an intense purple PL with a quantum yield, Φ_PL, of 0.22 (22%), owing to the effectively disturbed concentration quenching (CQ) in the fluorophore units by the bulky HFIP side groups. The chain ends of a wholly cycloaliphatic polyimide (PI), derived from 1,2,3,4-cyclobutanetetracarboxylic dianhydride (CBDA) and 4,4′-methylenebis(cyclohexylamine) (MBCHA), were modified with conjugated monoamines. The PI derived from 2,3,6,7-naphthalenetetracarboxylic dianhydride (2,3,6,7-NTDA) and MBCHA exhibited a very high glass transition temperature (T_g = 376 °C) and purple fluorescence from the S₁(π,π*) state. However, its Φ_PL value was lower than expected. A pronounced effect of fluorophore dilution using CBDA on the PL enhancement was observed. This is closely related to the planar structure of the 2,3,6,7-NTDA-based diimide units. By contrast, the counterpart using an 2,3,6,7-NTDA isomer, 1,4,5,8-NTDA, was virtually non-fluorescent, despite its sufficient dilution using CBDA. The PI film obtained using 3,3″,4,4″-p-terphenyltetracarboxylic dianhydride (TPDA) with a non-coplanar structure and MBCHA exhibited an intense blue fluorescence spectrum (Φ_PL = 0.26) peaking at 434 nm. The dilution approach using CBDA enhanced its fluorescence up to a high Φ_PL value of 0.41. Even when TPDA was combined with an aromatic diamine, 2,2′-bis(trifluoromethyl)benzidine (TFMB), the intense blue fluorescence was observed without charge-transfer fluorescence. A semi-cycloaliphatic PI derived from TFMB and a novel cycloaliphatic tetracarboxylic dianhydride, which was obtained from a hydrogenated trimellitic anhydride derivative and 4,4′-biphenol, was used as another host polymer for 9,10-bis(4-aminophenyl)anthracene (BAPA). The BAPA-incorporating PI film resulted in a significant PL enhancement with a considerably high Φ_PL of 0.48. This PI film also had a relatively high T_g (265 °C). A reactive dye, N,N′-bis[4-(4-amino-3-methylbenzyl)-2-methylphenyl]-3,4,9,10-perylenetetracarboxydiimide, was harnessed as a fluorescence probe to explore transamidation between polyimide precursors in solution. Full article

The solid-phase polymerization synthesis (SPPS) represents one of the most innovative approaches to the preparation of nano-sized molecularly imprinted polymers. One of its main features consists of the use of a solid support on which the template molecule is covalently grafted. It implies that the imprinting process does not involve the target molecule as is, but, rather, a structural modification of it. It is known that the rationally designed mimic N-(4-chloro-1-hydroxy-2-naphthoylamido)-(L)-phenylalanine (CHNA-Phe) is able to generate, by bulk polymerization, imprinted materials capable of recognizing the mycotoxin Ochratoxin A (OTA). In this work, we wanted to verify whether the CHNA-Phe can be a useful mimic template in the SPPS technique. The binding isotherm were measured in the pH range of 4–8 and the binding affinities for CHNA-Phe and OTA were compared, showing that CHNA-Phe-imprinted nanoMIPs recognize, in buffered water, equally well OTA, and that the overall molecular recognition depends markedly from pH-related ionic interactions between the ligand and the binding site. There results confirm that in the SPPS method, it is possible and convenient to use as mimic templates a molecule whose three-dimensional structure is to some extent different from the target without substantial loss of selectivity or binding affinity. Full article