Biocompatible bacterial cellulose-poly(2-hydroxyethyl methacrylate) nanocomposite films

Exploring nanocellulose frontiers: A comprehensive review of its extraction, properties, and pioneering applications in the automotive and biomedical industries

Material is an inseparable entity for humans to serve different purposes. However, synthetic polymers represent a major category of anthropogenic pollutants with detrimental impacts on natural ecosystems. This escalating environmental issue is characterized by the accumulation of non-biodegradable plastic materials, which pose serious threats to the health of our planet's ecosystem. Cellulose is becoming a focal point for many researchers due to its high availability. It has been used to serve various purposes. Recent scientific advancements have unveiled innovative prospects for the utilization of nanocellulose within the area of advanced science. This comprehensive review investigates deeply into the field of nanocellulose, explaining the methodologies employed in separating nanocellulose from cellulose. It also explains upon two intricately examined applications that emphasize the pivotal role of nanocellulose in nanocomposites. The initial instance pertains to the automotive sector, encompassing cutting-edge applications in electric vehicle (EV) batteries, while the second exemplifies the use of nanocellulose in the field of biomedical applications like otorhinolaryngology, ophthalmology, and wound dressing. This review aims to provide comprehensive information starting from the definitions, identifying the sources of the nanocellulose and its extraction, and ending with the recent applications in the emerging field such as energy storage and biomedical applications.

Contributions of Women in Recent Research on Biopolymer Science

Nowadays, biopolymers are playing a fundamental role in our society because of the environmental issues and concerns associated with synthetic polymers. The aim of this Special Issue entitled ‘Women in Polymer Science and Technology: Biopolymers’ is highlighting the work designed and developed by women on biopolymer science and technology. In this context, this short review aims to provide an introduction to this Special Issue by highlighting some recent contributions of women around the world on the particular topic of biopolymer science and technology during the last 20 years. In the first place, it highlights a selection of important works performed on a number of well-studied natural polymers, namely, agar, chitin, chitosan, cellulose, and collagen. Secondly, it gives an insight into the discovery of new polysaccharides and enzymes that have a role in their synthesis and in their degradation. These contributions will be paving the way for the next generation of female and male scientists on this topic.

Development of New Hybrid Casein-Loaded PHEMA-PEGDA Hydrogels with Enhanced Mineralisation Potential

Casein is a micellar protein rich in glutamic and aspartic acids as well as in phosphoserine. Considering its native affinity for calcium and the connection of sub-micelles through calcium phosphate nanoclusters, this protein holds promise for stimulating biomimetic mineralisation phenomena and direct binding with the mineral phase of hard tissues. In this work we prepared new hybrids based on casein embedded in a poly(2-hydroxyethyl methacrylate)-polyethyleneglycol diacrylate (PHEMA-PEGDA) hydrogel. The resulting materials were investigated structurally by Fourier transform infrared (FT-IR). Casein modified the water affinity and the rheological properties of the hybrids. The microstructure was explored by scanning electron microscopy (SEM) and the distribution of the protein was established by combined SEM micrographs and elemental mapping considering the casein-specific elements (P, N and S) not contained by the synthetic hydrogel matrix. The effect of casein on the mineralisation potential and stability of the mineral phase was investigated by FT-IR and SEM when alternating incubation in Ca/P solutions is performed. Increasing casein content in the hybrids leads to improved mineralisation, with localised formation of nanoapatite phase on the protein areas in the richest sample in protein. This behaviour was proved microstructurally by SEM and through overlapping elemental distribution of Ca and P from the newly formed mineral and P, S and N from the protein. This study indicates that nanoapatite-casein-PHEMA-PEGDA nanocomposites may be developed for potential use in bone repair and regeneration.

Numerical Study of Customized Artificial Cornea Shape by Hydrogel Biomaterials on Imaging and Wavefront Aberration

The blindness caused by cornea diseases has exacerbated many patients all over the world. The disadvantages of using donor corneas may cause challenges to recovering eye sight. Developing artificial corneas with biocompatibility may provide another option to recover blindness. The techniques of making individual artificial corneas that fit the biometric parameters for each person can be used to help these patients effectively. In this study, artificial corneas with different shapes (spherical, aspherical, and biconic shapes) are designed and they could be made by two different hydrogel polymers that form an interpenetrating polymer network for their excellent mechanical strength. Two designed cases for the artificial corneas are considered in the simulations: to optimize the artificial cornea for patients who still wear glasses and to assume that the patient does not wear glasses after transplanting with the optimized artificial cornea. The results show that the artificial corneas can efficiently decrease the imaging blur. Increasing asphericity of the current designed artificial corneas can be helpful for the imaging corrections. The differences in the optical performance of the optimized artificial corneas by using different materials are small. It is found that the optimized artificial cornea can reduce the high order aberrations for the second case.

Synthesis and Characterization Superabsorbent Polymers Made of Starch, Acrylic Acid, Acrylamide, Poly(Vinyl Alcohol), 2-Hydroxyethyl Methacrylate, 2-Acrylamido-2-methylpropane Sulfonic Acid

Three polymers with excellent absorption properties were synthesized by graft polymerization: soluble starch-g-poly(acrylic acid-co-2-hydroxyethyl methacrylate), poly(vinyl alcohol)/potato starch-g-poly(acrylic acid-co-acrylamide), poly(vinyl alcohol)/potato starch-g-poly(acrylic acid-co-acrylamide-co-2-acrylamido-2-methylpropane sulfonic acid). Ammonium persulfate and potassium persulfate were used as initiators, while N,N′-methylenebisacrylamide was used as the crosslinking agent. The molecular structure of potato and soluble starch grafted by synthetic polymers was characterized by means of Fourier Transform Infrared Spectroscopy (FTIR). The morphology of the resulting materials was studied using a scanning electron microscope (SEM). Thermal stability was tested by thermogravimetric measurements. The absorption properties of the obtained biopolymers were tested in deionized water, sodium chroma solutions of various concentrations and in buffer solutions of various pH.

Bacterial Nanocellulose toward Green Cosmetics: Recent Progresses and Challenges

In the skin care field, bacterial nanocellulose (BNC), a versatile polysaccharide produced by non-pathogenic acetic acid bacteria, has received increased attention as a promising candidate to replace synthetic polymers (e.g., nylon, polyethylene, polyacrylamides) commonly used in cosmetics. The applicability of BNC in cosmetics has been mainly investigated as a carrier of active ingredients or as a structuring agent of cosmetic formulations. However, with the sustainability issues that are underway in the highly innovative cosmetic industry and with the growth prospects for the market of bio-based products, a much more prominent role is envisioned for BNC in this field. Thus, this review provides a comprehensive overview of the most recent (last 5 years) and relevant developments and challenges in the research of BNC applied to cosmetic, aiming at inspiring future research to go beyond in the applicability of this exceptional biotechnological material in such a promising area.

Bacterial Nanocellulose in Dentistry: Perspectives and Challenges

Bacterial cellulose (BC) is a natural polymer that has fascinating attributes, such as biocompatibility, low cost, and ease of processing, being considered a very interesting biomaterial due to its options for moldability and combination. Thus, BC-based compounds (for example, BC/collagen, BC/gelatin, BC/fibroin, BC/chitosan, etc.) have improved properties and/or functionality, allowing for various biomedical applications, such as artificial blood vessels and microvessels, artificial skin, and wounds dressing among others. Despite the wide applicability in biomedicine and tissue engineering, there is a lack of updated scientific reports on applications related to dentistry, since BC has great potential for this. It has been used mainly in the regeneration of periodontal tissue, surgical dressings, intraoral wounds, and also in the regeneration of pulp tissue. This review describes the properties and advantages of some BC studies focused on dental and oral applications, including the design of implants, scaffolds, and wound-dressing materials, as well as carriers for drug delivery in dentistry. Aligned to the current trends and biotechnology evolutions, BC-based nanocomposites offer a great field to be explored and other novel features can be expected in relation to oral and bone tissue repair in the near future.

Understanding the Structure and Dynamics of Nanocellulose-Based Composites with Neutral and ionic Poly(methacrylate) Derivatives using Inelastic Neutron Scattering and DFT Calculations

Bacterial nanocellulose (BC)-based composites containing poly(2-hydroxyethyl methacrylate) (PHEMA), poly(methacroylcholine chloride) (PMACC) or poly(methacroylcholine hydroxide) (PMACH) were characterized by inelastic neutron scattering (INS) spectroscopy, combined with DFT (density functional theory) calculations of model systems. A reasonable match between calculated and experimental spectral lines and their intensities was used to support the vibrational assignment of the observed bands and to validate the possible structures. The differences between the spectra of the nanocomposites and the pure precursors indicate that interactions between the components are stronger for the ionic poly(methacrylate) derivatives than for the neutral counterpart. Displaced anions interact differently with cellulose chains, due to the different ability to compete with the O-H···O hydrogen bonds in cellulose. Hence, the INS is an adequate technique to delve deeper into the structure and dynamics of nanocellulose-based composites, confirming that they are true nanocomposite materials instead of simple mixtures of totally independent domains.

Nanocellulose-Based Patches Loaded with Hyaluronic Acid and Diclofenac towards Aphthous Stomatitis Treatment

Nanostructured patches composed of bacterial nanocellulose (BNC), hyaluronic acid (HA) and diclofenac (DCF) were developed, envisioning the treatment of aphthous stomatitis. Freestanding patches were prepared via diffusion of aqueous solutions of HA and DCF, with different concentrations of DCF, into the wet BNC three-dimensional porous network. The resultant dual polysaccharides-based patches with a nanostructured morphology present thermal stability up to 200 °C, as well as good dynamic mechanical properties, with a storage modulus higher than 1.0 GPa. In addition, the patches are non-cytotoxic to human keratinocytes (HaCaT cells), with a cell viability of almost 100% after 24 h. The in vitro release profile of DCF from the patches was evaluated in simulated saliva, and the data refer to a diffusion- and swelling-controlled drug-release mechanism. The attained results hint at the possibility of using these dual polysaccharides-based oral mucosal patches to target aphthous stomatitis.

High-strength cellulose-polyacrylamide hydrogels: Mechanical behavior and structure depending on the type of cellulose

Two types of stiff and high-strength composite hydrogels possessing the structure of interpenetrating polymer networks were synthesized via free-radical polymerization of acrylamide carried out straight within the previously formed physical network of regenerated plant cellulose or bacterial cellulose (PC and BC respectively) that was swollen in the reactive solution. The mechanical behavior of synthesized hydrogels subjected to the action of compressive deformations with different amplitude values was studied. The analysis of the stress-strain curves of compression tests of the hydrogels of both types obtained in different test conditions demonstrates the substantial difference in their mechanical behavior. Both the PC- and BC-based hydrogels withstand successfully the one-shot compression with the amplitude up to 80%, but in the conditions of the multiple compression tests (cyclic compressions) during the subsequent compression acts the dramatic increase in the stiffness of the BC-based hydrogels was observed at the deformation region beyond 60%. This effect can be explained by the deep reorganization of the intermolecular structure of the material with the stress-induced reorientation of BC micro-fibrils. Submicron- and micron-scale specific features of structures of composite hydrogels of both types were studied by cryo-scanning electron microscopy to explain the peculiarities of the mechanical effects observed.

Tailor-Made, Linear, and “Comb-Like” Polyester-Based Copolymers: Synthesis, Characterization, and Thermal Behavior of Potential 3D-Printing/Electrospinning Candidates

Tailor-made, linear, and “comb-like” poly(ε-caprolactone)-based copolymers were synthesized by employing a combination of controlled polymerization techniques. Poly(dimethylsiloxane-block-ε-caprolactone) copolymers (SCL#) were synthesized by a combination of anionic and ring-opening polymerization (ROP), whereas “comb-like” poly(hydroxyethylmethacrylate-co-(hydroxyethylmethacrylate-graft-ε-caprolactone)-block-ε-caprolactone) (HEMACL#) were synthesized through simultaneous ROP and reversible addition fragmentation chain transfer (RAFT) polymerization. Copolymers were characterized by hydrogen nuclear magnetic resonance (1H-NMR), size exclusion chromatography (SEC), and Fourier transform infrared (FTIR) spectroscopy. All polymers exhibited narrow molar masses distributions (Mw/Mn<1.54), and their thermal properties were analyzed by isothermal crystallization kinetics (Avrami’s theory, by using differential scanning calorimetry (DSC)) and by employing modulated thermogravimetric analysis (MTGA). The macromolecular structure exerts a noticeable effect on the PCL block behavior when compared to the PCL homopolymer, at least for the temperature range studied (16–24°C): less differences in thermal properties were observed for linear block copolymers, whereas for “comb-like” graft copolymers their final crystallization capacity strongly depends on the presence of branches. For both sets of copolymers, the decrease in the resulting melting temperatures and the increase in the half-life crystallization time values might be useful processing parameters, particularly if these copolymers are planned for using as an alternative source of 3D printing or electrospinning materials.

Bacterial cellulose as an example product for sustainable production and consumption

Life cycle of bacterial cellulose. Sustainable production and consumption of bio-based products are showcased using bacterial cellulose as an example.

A multipurpose natural and renewable polymer in medical applications: Bacterial cellulose

Bacterial cellulose (BC) produced by some bacteria, among them Gluconacetobacter xylinum, which secrets an abundant 3D networks fibrils, represents an interesting emerging biocompatible nanomaterial. Since its discovery BC has shown tremendous potential in a wide range of biomedical applications, such as artificial skin, artificial blood vessels and microvessels, wound dressing, among others. BC can be easily manipulated to improve its properties and/or functionalities resulting in several BC based nanocomposites. As example BC/collagen, BC/gelatin, BC/Fibroin, BC/Chitosan, etc. Thus, the aim of this review is to discuss about the applicability in biomedicine by demonstrating a variety of forms of this biopolymer highlighting in detail some qualities of bacterial cellulose. Therefore, various biomedical applications ranging from implants and scaffolds, carriers for drug delivery, wound-dressing materials, etc. that were reported until date will be presented.

Light-Cured Self-Etch Adhesives Undergo Hydroxyapatite-Triggered Self-Cure

Light cure is a popular mode of curing for dental adhesives. However, it suffers from inadequate light delivery when the restoration site is less accessible, in which case a self-cure mechanism is desirable to salvage any compromised polymerization. We previously reported a novel self-cure system mediated by ethyl 4-(dimethylamino)-benzoate (4E) and hydroxyapatite (HAp). The present work aims to investigate if such self-cure phenomenon takes place in adhesives that underwent prior inadequate light cure and to elucidate if HAp released from the dental etching process is sufficient to trigger it. Model self-etch adhesives were formulated with various components, including bis[2-methacryloyloxy)ethyl]-phosphate (2MP) as acidic monomer and trimethylbenzoyl-diphenylphosphine oxide (TPO) as photoinitiator. In vitro evolution of degree of conversion (DC) of HAp-incorporated adhesives was monitored by infrared spectroscopy during light irradiation and dark storage. Selected adhesives were allowed to etch and extract HAp from enamel, light-cured in situ, and stored in the dark, after which Raman line mapping was used to obtain spatially resolved DC across the enamel-resin interface. Results showed that TPO+4E adhesives reached DC similar to TPO-only counterparts upon completion of light irradiation but underwent another round of initiation that boosted DC to ~100% regardless of HAp level or prior light exposure. When applied to enamel, TPO-only adhesives had ~80% DC in resin, which gradually descended to ~50% in enamel, whereas TPO+4E adhesives consistently scored ~80% DC across the enamel-resin interface. These observations suggest that polymerization of adhesives that underwent insufficient light cure is salvaged by the novel self-cure mechanism, and such salvaging effect can be triggered by HAp released from dental substrate during the etching process.