Bacterial Nanocellulose Magnetically Functionalized for Neuro‐Endovascular Treatment

Translational applications of magnetic nanocellulose composites

Nanocellulose has emerged as a potential 'green' material owing to its inimitable properties. Furthermore, the significant development in technology has facilitated the design of multidimensional nanocellulose structures, including one-dimensional (1D: microparticles and nanofibers), two-dimensional (2D: coatings), and three-dimensional (3D: hydrogels/ferrogels) composites. In this case, nanocellulose composites blended with magnetic nanoparticles represent a new class of hybrid materials with improved biocompatibility and biodegradability. The application field of magnetic nanocellulose composites (MNCs) ranges from biomedicine and the environment to catalysis and sensing. In this review, we present the major applications of MNCs, emphasizing their innovative benefits and how they interconnect with translational applications in clinics and the environment. Additionally, we focus on the synthesis techniques and role of different additives in the fabrication of MNCs for achieving extremely precise and intricate tasks related to real-world applications. Subsequently, we reveal the recent interdisciplinary research on MNCs and discuss their mechanical, tribological, electrochemical, magnetic, and biological phenomena. Finally, this review concludes with a portrayal of computational modelling together with a glimpse of the various translational applications of MNCs. Therefore, it is anticipated that the current review will provide the readers with an extensive opportunity and a more comprehensive depiction related to the types, properties, and applications of MNCs.

Effect of addition of γ-poly glutamic acid on bacterial nanocellulose production under agitated culture conditions

BACKGROUND

Bacterial nanocellulose (BNC), a natural polymer material, gained significant popularity among researchers and industry. It has great potential in areas, such as textile manufacturing, fiber-based paper, and packaging products, food industry, biomedical materials, and advanced functional bionanocomposites. The main current fermentation methods for BNC involved static culture, as the agitated culture methods had lower raw material conversion rates and resulted in non-uniform product formation. Currently, studies have shown that the production of BNC can be enhanced by incorporating specific additives into the culture medium. These additives included organic acids or polysaccharides. γ-Polyglutamic acid (γ-PGA), known for its high polymerization, excellent biodegradability, and environmental friendliness, has found extensive application in various industries including daily chemicals, medicine, food, and agriculture.

RESULTS

In this particular study, 0.15 g/L of γ-PGA was incorporated as a medium additive to cultivate BNC under agitated culture conditions of 120 rpm and 30 ℃. The BNC production increased remarkably by 209% in the medium with 0.15 g/L γ-PGA and initial pH of 5.0 compared to that in the standard medium, and BNC production increased by 7.3% in the medium with 0.06 g/L γ-PGA. The addition of γ-PGA as a medium additive resulted in significant improvements in BNC production. Similarly, at initial pH levels of 4.0 and 6.0, the BNC production also increased by 39.3% and 102.3%, respectively. To assess the characteristics of the BNC products, scanning electron microscopy, Fourier transform infrared spectroscopy, and thermogravimetric analysis were used. The average diameter of BNC fibers, which was prepared from the medium adding 0.15 g/L γ-PGA, was twice thicker than that of BNC fibers prepared from the control culture medium. That might be because that polyglutamic acid relieved the BNC synthesis from the shear stress from the agitation.

CONCLUSIONS

This experiment held great significance as it explored the use of a novel medium additive, γ-PGA, to improve the production and the glucose conversion rate in BNC fermentation. And the BNC fibers became thicker, with better thermal stability, higher crystallinity, and higher degree of polymerization (DPv). These findings lay a solid foundation for future large-scale fermentation production of BNC using bioreactors.

An overview to nanocellulose clinical application: Biocompatibility and opportunities in disease treatment

Recently, the demand for organ transplantation has promptly increased due to the enhanced incidence of body organ failure, the increasing efficiency of transplantation, and the improvement in post-transplant outcomes. However, due to a lack of suitable organs for transplantation to fulfill current demand, significant organ shortage problems have emerged. Developing efficient technologies in combination with tissue engineering (TE) has opened new ways of producing engineered tissue substitutes. The use of natural nanoparticles (NPs) such as nanocellulose (NC) and nano-lignin should be used as suitable candidates in TE due to their desirable properties. Many studies have used these components to form scaffolds and three-dimensional (3D) cultures of cells derived from different tissues for tissue repair. Interestingly, these natural NPs can afford scaffolds a degree of control over their characteristics, such as modifying their mechanical strength and distributing bioactive compounds in a controlled manner. These bionanomaterials are produced from various sources and are highly compatible with human-derived cells as they are derived from natural components. In this review, we discuss some new studies in this field. This review summarizes the scaffolds based on NC, counting nanocrystalline cellulose and nanofibrillated cellulose. Also, the efficient approaches that can extract cellulose with high purity and increased safety are discussed. We concentrate on the most recent research on the use of NC-based scaffolds for the restoration, enhancement, or replacement of injured organs and tissues, such as cartilage, skin, arteries, brain, and bone. Finally, we suggest the experiments and promises of NC-based TE scaffolds.

Bacterial-Nanocellulose-Based Biointerfaces and Biomimetic Constructs for Blood-Contacting Medical Applications

Understanding the interaction between biomaterials and blood is critical in the design of novel biomaterials for use in biomedical applications. Depending on the application, biomaterials can be designed to promote hemostasis, slow or stop bleeding in an internal or external wound, or prevent thrombosis for use in permanent or temporary medical implants. Bacterial nanocellulose (BNC) is a natural, biocompatible biopolymer that has recently gained interest for its potential use in blood-contacting biomedical applications (e.g., artificial vascular grafts), due to its high porosity, shapeability, and tissue-like properties. To promote hemostasis, BNC has been modified through oxidation or functionalization with various peptides, proteins, polysaccharides, and minerals that interact with the coagulation cascade. For use as an artificial vascular graft or to promote vascularization, BNC has been extensively researched, with studies investigating different modification techniques to enhance endothelialization such as functionalizing with adhesion peptides or extracellular matrix (ECM) proteins as well as tuning the structural properties of BNC such as surface roughness, pore size, and fiber size. While BNC inherently exhibits comparable mechanical characteristics to endogenous blood vessels, these mechanical properties can be enhanced through chemical functionalization or through altering the fabrication method. In this review, we provide a comprehensive overview of the various modification techniques that have been implemented to enhance the suitability of BNC for blood-contacting biomedical applications and different testing techniques that can be applied to evaluate their performance. Initially, we focused on the modification techniques that have been applied to BNC for hemostatic applications. Subsequently, we outline the different methods used for the production of BNC-based artificial vascular grafts and to generate vasculature in tissue engineered constructs. This sequential organization enables a clear and concise discussion of the various modifications of BNC for different blood-contacting biomedical applications and highlights the diverse and versatile nature of BNC as a natural biomaterial.

Nano-embedded medical devices and delivery systems in interventional radiology

Nanomaterials research has significantly accelerated the development of the field of vascular and interventional radiology. The incorporation of nanoparticles with unique and functional properties into medical devices and delivery systems has paved the way for the creation of novel diagnostic and therapeutic procedures for various clinical disorders. In this review, we discuss the advancements in the field of interventional radiology and the role of nanotechnology in maximizing the benefits and mitigating the disadvantages of interventional radiology theranostic procedures. Several nanomaterials have been studied to improve the efficacy of interventional radiology interventions, reduce the complications associated with medical devices, improve the accuracy and efficiency of drug delivery systems, and develop innovative imaging modalities. Here, we summarize the recent progress in the development of medical devices and delivery systems that link nanotechnology in vascular and interventional radiology. This article is categorized under: Diagnostic Tools > Diagnostic Nanodevices Diagnostic Tools > In Vivo Nanodiagnostics and Imaging Therapeutic Approaches and Drug Discovery > Nanomedicine for Cardiovascular Disease.

Cellulose Structures as a Support or Template for Inorganic Nanostructures and Their Assemblies

Cellulose is the most abundant natural polymer and deserves the special attention of the scientific community because it represents a sustainable source of carbon and plays an important role as a sustainable energent for replacing crude oil, coal, and natural gas in the future. Intense research and studies over the past few decades on cellulose structures have mainly focused on cellulose as a biomass for exploitation as an alternative energent or as a reinforcing material in polymer matrices. However, studies on cellulose structures have revealed more diverse potential applications by exploiting the functionalities of cellulose such as biomedical materials, biomimetic optical materials, bio-inspired mechanically adaptive materials, selective nanostructured membranes, and as a growth template for inorganic nanostructures. This article comprehensively reviews the potential of cellulose structures as a support, biotemplate, and growing vector in the formation of various complex hybrid hierarchical inorganic nanostructures with a wide scope of applications. We focus on the preparation of inorganic nanostructures by exploiting the unique properties and performances of cellulose structures. The advantages, physicochemical properties, and chemical modifications of the cellulose structures are comparatively discussed from the aspect of materials development and processing. Finally, the perspective and potential applications of cellulose-based bioinspired hierarchical functional nanomaterials in the future are outlined.

A Versatile Strategy for the Fabrication of Poly(ethyl methacrylate) Composites

Poly(ethyl methacrylate) (PEMA) is dissolved in ethanol, known to be a non-solvent for PEMA, due to the solubilizing ability of an added bile acid biosurfactant, lithocholic acid (LA). The ability to avoid traditional toxic and carcinogenic solvents is important for the fabrication of composites for biomedical applications. The formation of concentrated solutions of high molecular weight PEMA is a key factor for the film deposition using the dip coating method. PEMA films provide corrosion protection for stainless steel. Composite films are prepared, containing bioceramics, such as hydroxyapatite and silica, for biomedical applications. LA facilitates dispersion of hydroxyapatite and silica in suspensions for film deposition. Ibuprofen and tetracycline are used as model drugs for the fabrication of composite films. PEMA-nanocellulose films are successfully prepared using the dip coating method. The microstructure and composition of the films are investigated. The conceptually new approach developed in this investigation represents a versatile strategy for the fabrication of composites for biomedical and other applications, using natural biosurfactants as solubilizing and dispersing agents.

Surface Modification of Bacterial Cellulose for Biomedical Applications

Bacterial cellulose is a naturally occurring polysaccharide with numerous biomedical applications that range from drug delivery platforms to tissue engineering strategies. BC possesses remarkable biocompatibility, microstructure, and mechanical properties that resemble native human tissues, making it suitable for the replacement of damaged or injured tissues. In this review, we will discuss the structure and mechanical properties of the BC and summarize the techniques used to characterize these properties. We will also discuss the functionalization of BC to yield nanocomposites and the surface modification of BC by plasma and irradiation-based methods to fabricate materials with improved functionalities such as bactericidal capabilities.

Iron Oxide Nanoparticles in Regenerative Medicine and Tissue Engineering

In recent years, many promising nanotechnological approaches to biomedical research have been developed in order to increase implementation of regenerative medicine and tissue engineering in clinical practice. In the meantime, the use of nanomaterials for the regeneration of diseased or injured tissues is considered advantageous in most areas of medicine. In particular, for the treatment of cardiovascular, osteochondral and neurological defects, but also for the recovery of functions of other organs such as kidney, liver, pancreas, bladder, urethra and for wound healing, nanomaterials are increasingly being developed that serve as scaffolds, mimic the extracellular matrix and promote adhesion or differentiation of cells. This review focuses on the latest developments in regenerative medicine, in which iron oxide nanoparticles (IONPs) play a crucial role for tissue engineering and cell therapy. IONPs are not only enabling the use of non-invasive observation methods to monitor the therapy, but can also accelerate and enhance regeneration, either thanks to their inherent magnetic properties or by functionalization with bioactive or therapeutic compounds, such as drugs, enzymes and growth factors. In addition, the presence of magnetic fields can direct IONP-labeled cells specifically to the site of action or induce cell differentiation into a specific cell type through mechanotransduction.

Bacterial Nanocellulose as a Scaffold for In Vitro Cell Migration Assay

Bacterial nanocellulose (BNC) stands out among polymers as a promising biomaterial due to its mechanical strength, hydrophilicity, biocompatibility, biodegradability, low toxicity and renewability. The use of scaffolds based on BNC for 3D cell culture has been previously demonstrated. The study exploited excellent properties of the BNC to develop an efficient and low-cost in vitro cell migration assay. The BNC scaffold was introduced into a cell culture 24 h after the SW480 cells were seeded, and cells were allowed to enter the scaffold within the next 24–48 h. The cells were stained with different fluorophores either before or after the introduction of the scaffold in the culture. Untreated cells were observed to enter the BNC scaffold in significant numbers, form clusters and retain a high viability after 48 h. To validate the assay’s usability for drug development, the treatments of SW480 cells were performed using aspirin, an agent known to reduce the migratory potential of this cell line in culture. This study demonstrates the application of BNC as a scaffold for cell migration testing as a low-cost alternative to commercial assays based on the Boyden chamber principle. The assay could be further developed for routine use in cancer research and anticancer drug development.

Use of Super Paramagnetic Iron Oxide Nanoparticles as Drug Carriers in Brain and Ear: State of the Art and Challenges

Drug delivery and distribution in the central nervous system (CNS) and the inner ear represent a challenge for the medical and scientific world, especially because of the blood-brain and the blood-perilymph barriers. Solutions are being studied to circumvent or to facilitate drug diffusion across these structures. Using superparamagnetic iron oxide nanoparticles (SPIONs), which can be coated to change their properties and ensure biocompatibility, represents a promising tool as a drug carrier. They can act as nanocarriers and can be driven with precision by magnetic forces. The aim of this study was to systematically review the use of SPIONs in the CNS and the inner ear. A systematic PubMed search between 1999 and 2019 yielded 97 studies. In this review, we describe the applications of the SPIONS, their design, their administration, their pharmacokinetic, their toxicity and the methods used for targeted delivery of drugs into the ear and the CNS.

Bacterial cellulose-based magnetic nanocomposites: A review

Bacterial cellulose (BC) is a natural polymer that has unique and interesting structural, physical and chemical properties. These characteristics make it very attractive as a starting point for several novel developments in innovative research. However, the pristine BC lacks certain properties, in particular, magnetic property, which can be imparted to BC by incorporation of several types of magnetic nanoparticles. Magnetic nanocomposites based on BC exhibit additional magnetic functionality on top of the excellent properties of pristine BC, which make them promising materials with potential uses in various medical and environmental applications, as well as in advanced electronic devices. This review has compiled information about all classes of BC magnetic nanocomposites fabricated by various synthesis approaches and an overview of applications as well as improved features of these materials. A summary of the key developments of BC magnetic nanocomposites and emphasis on novel advances in this field is presented.

Nanocellulose Hybrids with Metal Oxides Nanoparticles for Biomedical Applications

Cellulose is one of the most affordable, sustainable and renewable resources, and has attracted much attention especially in the form of nanocellulose. Bacterial cellulose, cellulose nanocrystals or nanofibers may serve as a polymer support to enhance the effectiveness of metal nanoparticles. The resultant hybrids are valuable materials for biomedical applications due to the novel optical, electronic, magnetic and antibacterial properties. In the present review, the preparation methods, properties and application of nanocellulose hybrids with different metal oxides nanoparticles such as zinc oxide, titanium dioxide, copper oxide, magnesium oxide or magnetite are thoroughly discussed. Nanocellulose-metal oxides antibacterial formulations are preferred to antibiotics due to the lack of microbial resistance, which is the main cause for the antibiotics failure to cure infections. Metal oxide nanoparticles may be separately synthesized and added to nanocellulose (ex situ processes) or they can be synthesized using nanocellulose as a template (in situ processes). In the latter case, the precursor is trapped inside the nanocellulose network and then reduced to the metal oxide. The influence of the synthesis methods and conditions on the thermal and mechanical properties, along with the bactericidal and cytotoxicity responses of nanocellulose-metal oxides hybrids were mainly analyzed in this review. The current status of research in the field and future perspectives were also signaled.

Synthesis and SERS application of gold and iron oxide functionalized bacterial cellulose nanocrystals (Au@Fe3O4@BCNCs)

Bacterial cellulose nanocrystals (BCNCs) are biocompatible cellulose nanomaterials that can host guest nanoparticles to form hybrid nanocomposites with a wide range of applications. Herein, we report the synthesis of a hybrid nanocomposite that consists of plasmonic gold nanoparticles (AuNPs) and superparamagnetic iron oxide (Fe3O4) nanoparticles supported on BCNCs. As a proof of concept, the hybrid nanocomposites were employed to isolate and detect malachite green isothiocyanate (MGITC) via magnetic separation and surface-enhanced Raman scattering (SERS). Different initial gold precursor (Au3+) concentrations altered the size and morphology of the AuNPs formed on the nanocomposites. The use of 5 and 10 mM Au3+ led to a heterogenous mix of spherical and nanoplate AuNPs with increased SERS enhancements, as compared to the more uniform AuNPs formed using 1 mM Au3+. Rapid and sensitive detection of MGITC at concentrations as low as 10-10 M was achieved. The SERS intensity of the normalized Raman peak at 1175 cm-1 exhibited a log-linear relationship for MGITC concentrations between 2 × 10-10 and 2 × 10-5 M for Au@Fe3O4@BCNCs. These results suggest the potential of these hybrid nanocomposites for application in a broad range of analyte detection strategies.

Controlled Anchoring of Iron Oxide Nanoparticles on Polymeric Nanofibers: Easy Access to Core@Shell Organic-Inorganic Nanocomposites for Magneto-Scaffolds

Composites combining superparamagnetic iron oxide nanoparticles (SPIONs) and polymers are largely present in modern (bio)materials. However, although SPIONs embedded in polymer matrices are classically reported, the mechanical and degradation properties of the polymer scaffold are impacted by the SPIONs. Therefore, the controlled anchoring of SPIONs onto polymer surfaces is still a major challenge. Herein, we propose an efficient strategy for the direct and uniform anchoring of SPIONs on the surface of functionalized-polylactide (PLA) nanofibers via a simple free ligand exchange procedure to design PLA@SPIONs core@shell nanocomposites. The resulting PLA@SPIONs hybrid biomaterials are characterized by electron microscopy (scanning electron microscopy and transmission electron microscopy) and energy-dispersive X-ray spectroscopy analysis to probe the morphology and detect elements present at the organic-inorganic interface, respectively. A monolayer of SPIONs with a complete and homogeneous coverage is observed on the surface of PLA nanofibers. Magnetization experiments show that magnetic properties of the nanoparticles are well preserved after their grafting on the PLA fibers and that the size of the nanoparticles does not change. The absence of cytotoxicity, combined with a high sensitivity of detection in magnetic resonance imaging both in vitro and in vivo, makes these hybrid nanocomposites attractive for the development of magnetic biomaterials for biomedical applications.

Versatile Application of Nanocellulose: From Industry to Skin Tissue Engineering and Wound Healing

Nanocellulose is cellulose in the form of nanostructures, i.e., features not exceeding 100 nm at least in one dimension. These nanostructures include nanofibrils, found in bacterial cellulose; nanofibers, present particularly in electrospun matrices; and nanowhiskers, nanocrystals, nanorods, and nanoballs. These structures can be further assembled into bigger two-dimensional (2D) and three-dimensional (3D) nano-, micro-, and macro-structures, such as nanoplatelets, membranes, films, microparticles, and porous macroscopic matrices. There are four main sources of nanocellulose: bacteria (Gluconacetobacter), plants (trees, shrubs, herbs), algae (Cladophora), and animals (Tunicata). Nanocellulose has emerged for a wide range of industrial, technology, and biomedical applications, namely for adsorption, ultrafiltration, packaging, conservation of historical artifacts, thermal insulation and fire retardation, energy extraction and storage, acoustics, sensorics, controlled drug delivery, and particularly for tissue engineering. Nanocellulose is promising for use in scaffolds for engineering of blood vessels, neural tissue, bone, cartilage, liver, adipose tissue, urethra and dura mater, for repairing connective tissue and congenital heart defects, and for constructing contact lenses and protective barriers. This review is focused on applications of nanocellulose in skin tissue engineering and wound healing as a scaffold for cell growth, for delivering cells into wounds, and as a material for advanced wound dressings coupled with drug delivery, transparency and sensorics. Potential cytotoxicity and immunogenicity of nanocellulose are also discussed.

In situ Study Unravels Bio-Nanomechanical Behavior in a Magnetic Bacterial Nano-cellulose (MBNC) Hydrogel for Neuro-Endovascular Reconstruction

Surgical clipping and endovascular coiling are well recognized as conventional treatments of Penetrating Brain Injury aneurysms. These clinical approaches show partial success, but often result in thrombus formation and the rupture of aneurysm near arterial walls. The authors address these challenging brain traumas with a unique combination of a highly biocompatible biopolymer hydrogel rendered magnetic in a flexible and resilient membrane coating integrated to a scaffold stent platform at the aneurysm neck orifice, which enhances the revascularization modality. This work focuses on the in situ diagnosis of nano-mechanical behavior of bacterial nanocellulose (BNC) membranes in an aqueous environment used as tissue reconstruction substrates for cerebral aneurysmal neck defects. Nano-mechanical evaluation, performed using instrumented nano-indentation, shows with very low normal loads between 0.01 to 0.5 mN, in the presence of deionized water. Mechanical testing and characterization reveals that the nano-scale response of BNC behaves similar to blood vessel walls with a very low Young´s modulus, E (0.0025 to 0.04 GPa), and an evident creep effect (26.01 ± 3.85 nm s^-1 ). These results confirm a novel multi-functional membrane using BNC and rendered magnetic with local adhesion of iron-oxide magnetic nanoparticles.

Magnetic targeting of smooth muscle cells in vitro using a magnetic bacterial cellulose to improve cell retention in tissue-engineering vascular grafts

Tissue-engineered vascular grafts (TEVG) use biologically-active cells with or without supporting scaffolds to achieve tissue remodeling and regrowth of injured blood vessels. However, this process may take several weeks because the high hemodynamic shear stress at the damaged site causes cellular denudation and impairs tissue regrowth. We hypothesize that a material with magnetic properties can provide the force required to speed up re-endothelization at the vascular defect by facilitating high cell density coverage, especially during the first 24 h after implantation. To test our hypothesis, we designed a magnetic bacterial cellulose (MBC) to locally target cells in vitro under a pulsatile fluid flow (0.514 dynes cm^-2). This strategy can potentially increase cell homing at TEVG, without the need of blood cessation. The MBC was synthesized by an in situ precipitation method of Fe³⁺ and Fe²⁺ iron salts into bacterial cellulose (BC) pellicles to form Fe₃O₄ nanoparticles along the BC's fibrils, followed by the application of dextran coating to protect the embedded nanoparticles from oxidation. The iron salt concentration used in the synthesis of the MBC was tuned to balance the magnetic properties and cytocompatibility of the magnetic hydrogel. Our results showed a satisfactory MBC magnetization of up to 10 emu/g, which is above the value considered relevant for tissue engineering applications (0.05 emu/g). The MBC captured magnetically-functionalized cells under dynamic flow conditions in vitro. MBC magnetic properties and cytocompatibility indicated a dependence on the initial iron oxide nanoparticle concentration.

STATEMENT OF SIGNIFICANCE

Magnetic hydrogels represent a new class of functional materials with great potential in TVEG because they offer a platform to (1) release drugs on demand, (2) speed up tissue regrowth, and (3) provide mechanical cues to cells by its deformability capabilities. Here, we showed that a magnetic hydrogel, the MBC, was able to capture and retain magnetically-functionalized smooth muscle cells under pulsatile flow conditions in vitro. A magnetic hydrogel with this feature can be used to obtain high-density cell coverage on sites that are aggressive for cell survival such as the luminal face of vascular grafts, whereas simultaneously can support the formation of a biologically-active cell layer that protects the material from restenosis and inflammation.