Simultaneous regeneration of calcium lactate and cellulose into PCL nanofiber for biomedical application

From electricity to vitality: the emerging use of piezoelectric materials in tissue regeneration

The unique ability of piezoelectric materials to generate electricity spontaneously has attracted widespread interest in the medical field. In addition to the ability to convert mechanical stress into electrical energy, piezoelectric materials offer the advantages of high sensitivity, stability, accuracy and low power consumption. Because of these characteristics, they are widely applied in devices such as sensors, controllers and actuators. However, piezoelectric materials also show great potential for the medical manufacturing of artificial organs and for tissue regeneration and repair applications. For example, the use of piezoelectric materials in cochlear implants, cardiac pacemakers and other equipment may help to restore body function. Moreover, recent studies have shown that electrical signals play key roles in promoting tissue regeneration. In this context, the application of electrical signals generated by piezoelectric materials in processes such as bone healing, nerve regeneration and skin repair has become a prospective strategy. By mimicking the natural bioelectrical environment, piezoelectric materials can stimulate cell proliferation, differentiation and connection, thereby accelerating the process of self-repair in the body. However, many challenges remain to be overcome before these concepts can be applied in clinical practice, including material selection, biocompatibility and equipment design. On the basis of the principle of electrical signal regulation, this article reviews the definition, mechanism of action, classification, preparation and current biomedical applications of piezoelectric materials and discusses opportunities and challenges for their future clinical translation.

Biological properties of polycaprolactone and barium titanate composite in biomedical applications

The ceramic-polymer composite materials are widely known for their exceptional mechanical and biological properties. Polycaprolactone (PCL) is a biodegradable polymer material extensively used in various biomedical applications. At the same time, barium titanate (BT), a ceramic material, exhibits piezoelectric properties similar to bone, which is essential for osseointegration. Furthermore, a composite material that combines the benefits of PCL and BT results in an innovative composite material with enhanced properties for biomedical applications. Thus, this review is organised into three sections. Firstly, it aims to provide an overview of the current research on evaluating biological properties, including antibacterial activity, cytotoxicity and osseointegration, of PCL polymeric matrices in its pure form and reinforced structures with ceramics, polymers and natural extracts. The second section investigates the biological properties of BT, both in its pure form and in combination with other supporting materials. Finally, the third section provides a summary of the biological properties of the PCLBT composite material. Furthermore, the existing challenges of PCL, BT and their composites, along with future research directions, have been presented. Therefore, this review will provide a state-of-the-art understanding of the biological properties of PCL and BT composites as potential futuristic materials in biomedical applications.

Preparation and research of PCL/cellulose composites: Cellulose derived from agricultural wastes

For the rational use of agricultural wastes, bagasse, orange peel and wheat bran were used to fabricate bio-based polymer materials. Cellulose was extracted from the three different agricultural wastes, and poly(ε-caprolactone) (PCL) was used as the matrix material. PCL was mixed with nanocrystalline cellulose (CNC), extracted bagasse cellulose (GC), orange peel cellulose (JC) and wheat bran cellulose (MC) by solution casting. Morphology and structure of the extracted cellulose were studied by Scanning Electron Microscope, Fourier Infrared spectrometer, thermogravimetry and X-ray diffractometer. The influence of GC, JC, MC on the crystallization process and mechanical properties of PCL was investigated by DSC and tensile test. Experimental results show that the addition of CNC, GC, JC, MC increases the crystallization temperature of PCL, accelerates the crystallization process of PCL, and improves the tensile property of PCL.

Electroconductive Polythiophene Nanocomposite Fibrous Scaffolds for Enhanced Osteogenic Differentiation via Electrical Stimulation

Biophysical cues are key distinguishing characteristics that influence tissue development and regeneration, and significant efforts have been made to alter the cellular behavior by means of cell-substrate interactions and external stimuli. Electrically conductive nanofibers are capable of treating bone defects since they closely mimic the fibrillar architecture of the bone matrix and deliver the endogenous and exogenous electric fields required to direct cell activities. Nevertheless, previous studies on conductive polymer-based scaffolds have been limited to polypyrrole, polyaniline, and poly(3,4-ethylenedioxythiophene) (PEDOT). In the present study, chemically synthesized polythiophene nanoparticles (PTh NPs) are incorporated into polycaprolactone (PCL) nanofibers, and subsequent changes in physicochemical, mechanical, and electrical properties are observed in a concentration-dependent manner. In murine preosteoblasts (MC3T3-E1), we examine how substrate properties modified by adding PTh NPs contribute to changes in the cellular behavior, including viability, proliferation, differentiation, and mineralization. Additionally, we determine that external electrical stimulation (ES) mediated by PTh NPs positively affects such osteogenic responses. Together, our results provide insights into polythiophene's potential as an electroconductive composite scaffold material.

Inhibition of Escherichia Virus MS2, Surrogate of SARS-CoV-2, via Essential Oils-Loaded Electrospun Fibrous Mats: Increasing the Multifunctionality of Antivirus Protection Masks

One of the most important measures implemented to reduce SARS-CoV-2 transmission has been the use of face masks. Yet, most mask options available in the market display a passive action against the virus, not actively compromising its viability. Here, we propose to overcome this limitation by incorporating antiviral essential oils (EOs) within polycaprolactone (PCL) electrospun fibrous mats to be used as intermediate layers in individual protection masks. Twenty EOs selected based on their antimicrobial nature were examined for the first time against the Escherichia coli MS2 virus (potential surrogate of SARS-CoV-2). The most effective were the lemongrass (LGO), Niaouli (NO) and eucalyptus (ELO) with a virucidal concentration (VC) of 356.0, 365.2 and 586.0 mg/mL, respectively. PCL was processed via electrospinning, generating uniform, beadless fibrous mats. EOs loading was accomplished via two ways: (1) physisorption on pre-existing mats (PCLaEOs), and (2) EOs blending with the polymer solution prior to fiber electrospinning (PCLbEOs). In both cases, 10% v/v VC was used as loading concentration, so the mats' stickiness and overwhelming smell could be prevented. The EOs presence and release from the mats were confirmed by UV-visible spectroscopy (≈5257-631 µg) and gas chromatography-mass spectrometry evaluations (average of ≈14.3% EOs release over 4 h), respectively. PCLbEOs mats were considered the more mechanically and thermally resilient, with LGO promoting the strongest bonds with PCL (PCLbLGO). On the other hand, PCLaNO and PCLaELO were deemed the least cohesive combinations. Mats modified with the EOs were all identified as superhydrophobic, capable of preventing droplet penetration. Air and water-vapor permeabilities were affected by the mats' porosity (PCL < PCLaEOs < PCLbEOs), exhibiting a similar tendency of increasing with the increase of porosity. Antimicrobial testing revealed the mats' ability to retain the virus (preventing infiltration) and to inhibit its action (log reduction averaging 1). The most effective combination against the MS2 viral particles was the PCLbLGO. These mats' scent was also regarded as the most pleasant during sensory evaluation. Overall, data demonstrated the potential of these EOs-loaded PCL fibrous mats to work as COVID-19 active barriers for individual protection masks.

Osteon-mimetic 3D nanofibrous scaffold enhances stem cell proliferation and osteogenic differentiation for bone regeneration

The scaffold microstructure is important for bone tissue engineering. Failure to synergistically imitate the hierarchical microstructure of the components of bone, such as an osteon with concentric multilayers assembled by nanofibers, hinders the performance for guiding bone regeneration. Here, a 2D bilayer nanofibrous membrane (BLM) containing poly(lactide-co-glycolide) (PLGA)/polycaprolactone (PCL) composite membranes in similar compositions (PCL15 and PCL20), but possessing different degrees of shrinkage, was fabricated via sequential electrospinning. Upon incubation in phosphate buffered saline (PBS) (37 °C), the 2D BLM spontaneously deformed into a 3D shape induced by PCL crystallization within the PLGA matrix, and the PCL15 and PCL20 layer formed a concave and convex surface, respectively. The 3D structure contained curved multilayers with an average diameter of 776 ± 169 μm, and on the concave and convex surface the nanofiber diameters were 792 ± 225 and 881 ± 259 nm, respectively. The initial 2D structure facilitated the even distribution of seeded cells. Adipose-derived stem cells from rats (rADSCs) proliferated faster on a concave surface than on a convex surface. For the 3D BLM, the osteogenic differentiation of rADSCs was significantly higher than that on 2D surfaces, even without osteogenic supplements, which resulted from the stretched cell morphology on the curved sublayer leading to increased expression of lamin-A. After being implanted into cranial defects in Sprague Dawley (SD) rats, 3D BLM significantly accelerated bone formation. In summary, 3D BLM with an osteon-like structure provides a potential strategy to repair bone defects.

Development of Immediate Release Tablets Containing Calcium Lactate Synthetized from Black Sea Mussel Shells

Nowadays, the use of marine by-products as precursor materials has gained great interest in the extraction and production of chemical compounds with suitable properties and possible pharmaceutical applications. The present paper presents the development of a new immediate release tablet containing calcium lactate obtained from Black Sea mussel shells. Compared with other calcium salts, calcium lactate has good solubility and bioavailability. In the pharmaceutical preparations, calcium lactate was extensively utilized as a calcium source for preventing and treating calcium deficiencies. The physical and chemical characteristics of synthesized calcium lactate were evaluated using Fourier Transform Infrared Spectroscopy, X-ray diffraction analysis and thermal analysis. Further, the various pharmacotechnical properties of the calcium lactate obtained from mussel shells were determined in comparison with an industrial used direct compressible Calcium lactate DC (PURACAL^®). The obtained results suggest that mussel shell by-products are suitable for the development of chemical compounds with potential applications in the pharmaceutical domain.

Multi-Functional Core-Shell Nanofibers for Wound Healing

Core-shell nanofibers have great potential for bio-medical applications such as wound healing dressings where multiple drugs and growth factors are expected to be delivered at different healing phases. Compared to monoaxial nanofibers, core-shell nanofibers can control the drug release profile easier, providing sustainable and effective drugs and growth factors for wound healing. However, it is challenging to produce core-shell structured nanofibers with a high production rate at low energy consumption. Co-axial centrifugal spinning is an alternative method to address the above limitations to produce core-shell nanofibers effectively. In this study, a co-axial centrifugal spinning device was designed and assembled to produce core-shell nanofibers for controlling the release rate of ibuprofen and hEGF in inflammation and proliferation phases during the wound healing process. Core-shell structured nanofibers were confirmed by TEM. This work demonstrated that the co-axial centrifugal spinning is a high productivity process that can produce materials with a 3D environment mimicking natural tissue scaffold, and the specific drug can be loaded into different layers to control the drug release rate to improve the drug efficiency and promote wound healing.

Vitamin D3-loaded electrospun cellulose acetate/polycaprolactone nanofibers: Characterization, in-vitro drug release and cytotoxicity studies

Vitamin D deficiency is now a global health problem; despite several drug delivery systems for carrying vitamin D due to low bioavailability and loss bioactivity. Developing a new drug delivery system to deliver vitamin D₃ is a strong incentive in the current study. Hence, an implantable drug delivery system (IDDS) was developed from the electrospun cellulose acetate (CA) and ε-polycaprolactone (PCL) nanofibrous membrane, in which the core of implants consists of vitamin D₃-loaded CA nanofiber (CAVD) and enclosed in a thin layer of the PCL membrane (CAVD/PCL). CA nanofibrous mat loaded with vitamin D₃ at the concentrations of 6, 12, and 20% (w/w) of vitamin D₃ were produced using electrospinning. The smooth and bead-free fibers with diameters ranged from 324 to 428 nm were obtained. The fiber diameters increased with an increase in vitamin D₃ content. The controlled drug release profile was observed over 30-days, which fit with the zero-order model (R² > 0.96) in the first stage. The mechanical properties of IDDS were improved. Young's modulus and tensile strength of CAVD/PCL (dry) were161 ± 14 and 13.07 ± 2.5 MPa, respectively. CA and PCL nanofibers are non-cytotoxic based on the results of the in-vitro cytotoxicity studies. This study can further broaden in-vivo study and provide a reference for developing a new IDDS to carry vitamin D₃ in the future.

Electropsun Polycaprolactone Fibres in Bone Tissue Engineering: A Review

Regeneration of bone tissue requires novel load bearing, biocompatible materials that support adhesion, spreading, proliferation, differentiation, mineralization, ECM production and maturation of bone-forming cells. Polycaprolactone (PCL) has many advantages as a biomaterial for scaffold production including tuneable biodegradation, relatively high mechanical toughness at physiological temperature. Electrospinning produces nanofibrous porous matrices that mimic many properties of natural tissue extracellular matrix with regard to surface area, porosity and fibre alignment. The biocompatibility and hydrophilicity of PCL nanofibres can be improved by combining PCL with other biomaterials to form composite scaffolds for bone regeneration. This work reviews the most recent research on synthesis, characterization and cellular response to nanofibrous PCL scaffolds and the composites of PCL with other natural and synthetic materials for bone tissue engineering.

High pressure laminates reinforced with electrospun cellulose acetate nanofibers

In the work, the non-woven cellulose acetate (CA) nanofiber mats were prepared via electrospinning, and CA nanofiber were incorporated into the core layer of the high-pressure laminates (HPLs). When the concentration of CA was 16 wt%, SEM images demonstrated that the morphology of the CA nanofiber mat was the best, with an average diameter of 654±246 nm. When CA nanofiber mats were incorporated into the core layer of HPLs, the mechanical properties of the resulted HPLs composites were significantly improved. Specifically, the tensile strength and elongation at break of the nanofiber mats reinforced HPLs composites increased remarkably to 40.8 ±1.1 MPa and 27.9 ± 0.9 %, respectively, which were nearly 6 times and 4.4 times higher than those of the pure HPLs. Furthermore, the incorporation of the CA nanofiber mats also significantly improved the flame retardancy of the HPLs, which was revealed from the thermogravimetric analysis (TGA) results.

Simple conversion of 3D electrospun nanofibrous cellulose acetate into a mechanically robust nanocomposite cellulose/calcium scaffold

Cellulose and its derivatives are widely used as nanofibrous biomaterials, but obtaining 3D cellulose nanofibers is difficult and relevant research is scarce. In the present study, we propose a simple method for converting electrospun 3D cellulose acetate/lactic acid nanofibers via calcium hydroxide treatment into a 3D cellulose/calcium lactate nanocomposite matrix. The conversion resulted in producing a stronger nanofibrous matrix (1.382 MPa vs. 0.112 MPa) that is more hydrophilic and cell-friendly compared to the untreated cellulose acetate/lactic acid group. The successful conversion was verified via FTIR, XPS, TGA, DTG, and XRD. The ability of the scaffolds to provide a suitable environment for cell growth and infiltration was verified by CCK assay and confocal microscopy. The porous nature, mechanical strength, and presence of calcium make the 3D cellulose/calcium lactate matrix a promising material for bone tissue engineering.

Integrated design and fabrication strategies for biomechanically and biologically functional PLA/β-TCP nanofiber reinforced GelMA scaffold for tissue engineering applications

We present an integrated design and fabrication strategy for the development of hierarchically structured biomechanically and biologically functional tissue scaffold. An integration of β-TCP incorporated fluffy type nanofibers and biodegradable interpenetrating gelatin-hydrogel networks (IGN) result in biomimetic tissue engineered constructs with fully tunable properties that can match specific tissue requirements. FESEM images showed that nanofibers were efficiently assembled into an orientation of IGN without disturbing its pore architecture. The pore architecture, compressive stiffness and modulus, swelling, and the biological properties of the composite constructs can be tailored by adjusting the composition of nanofiber content with respect to IGN. Experimental results of cell proliferation assay and confocal microscopy imaging showed that the as-fabricated composite constructs exhibit excellent ability for MC3T3-E1 cell proliferation, infiltration and growth. Furthermore, β-TCP incorporated functionalized nanofiber enhanced the biomimetic mineralization, cell infiltration and cell proliferation. Within two weeks of cell-seeding, the composite construct exhibited enhanced osteogenic performance (Runx2, osterix and ALP gene expression) compared to pristine IGN hydrogel scaffold. Our integrated design and fabrication approach enables the assembly of nanofiber within IGN architecture, laying the foundation for biomimetic scaffold.

Electrospinning of multifunctional cellulose acetate membrane and its adsorption properties for ionic dyes

Electrospinning of cellulose acetate with appropriated solvent system is the most straightforward method for fabricating micro- and nanofibers. To simultaneously and effectively remove both cationic and anionic dyes, a novel cost-effective multifunctional cellulose acetate (CA) fibers membrane was prepared by electrospinning followed by deacetylation, carboxymethylation and polydopamine (PDA) coating. The adsorption properties of PDA@DCA-COOH membrane were evaluated with methylene blue (MB) and Congo red (CR) as the ionic representatives for their removal. The results indicated that carboxyl, hydroxyl and amine multifunctional groups had been successfully grafted on the surface of the nanofibers with the maximum adsorption capacities of 69.89 and 67.31 mg g-1 for MB and CR, respectively, in the individual systems. The effect of co-existed dyes, inorganic salts and surfactants on the uptake of MB and CR in the simulated real complex system was strongly depended on the initial pH and ionic strength of the solution. The excellent adsorption capacities of the composite membrane were due to strong electrostatic attraction through the abundant functional groups on PDA@DCA-COOH surface. Based on its excellent recycling performance and adsorption property, PDA@DCA-COOH has a promising potential as an effective adsorbent in water treatment.

In Situ Biological Transmutation of Catalytic Lactic Acid Waste into Calcium Lactate in a Readily Processable Three-Dimensional Fibrillar Structure for Bone Tissue Engineering

A bioinspired three-dimensional (3D) fibrous structure possesses biomimicry, valuable functionality, and performance to scaffolding in tissue engineering. In particular, an electrospun fibrous mesh has been studied as a scaffold material in various tissue regeneration applications. We produced a low-density 3D polycaprolactone/lactic acid (LA) fibrous mesh (3D-PCLS) via the novel lactic-assisted 3D electrospinning technique exploiting the catalytic properties of LA as we reported previously. In the study, we demonstrated a strategy of recycling the LA component to synthesize the osteoinductive biomolecules in situ, calcium lactate (CaL), thereby forming a 3D bioactive PCL/CaL fibrous scaffold (3D-SCaL) for bone tissue engineering. The fiber morphology of 3D-PCLS and its packing degree could have been tailored by modifying the spinning solution and the collector design. 3D-SCaL demonstrated successful conversion of CaL from LA and exhibited the significantly enhanced biomineralization capacity, cell infiltration and proliferation rate, and osteoblastic differentiation in vitro with two different cell lines, MC3T3-e1 and bone marrow stem cells. In conclusion, 3D-SCaL proves to be a highly practical and accessible strategy using a variety of polymers to produce 3D fibers as a potential candidate for future regenerative medicine and tissue engineering applications.

Polycaprolactone as biomaterial for bone scaffolds: Review of literature

Bone tissue engineering using polymer based scaffolds have been studied a lot in last decades. Considering the qualities of all the polymers desired to be used as scaffolds, Polycaprolactone (PCL) polyester apart from being biocompatible and biodegradable qualifies to an appreciable level due its easy availability, cost efficacy and suitability for modification. Its adjustable physio-chemical state, biological properties and mechanical strength renders it to withstand physical, chemical and mechanical, insults without significant loss of its properties. This review aims to critically analyse the efficacy of PCL as a biomaterial for bone scaffolds.