Fabrication and evaluation of poly(lactic acid), chitosan, and tricalcium phosphate biocomposites for guided bone regeneration

Biocomposite-based strategies for dental bone regeneration

OBJECTIVE

Because of the anatomical complexity of the oral and maxillofacial sites, repairing bone defects in these regions is very difficult. This review article aims to consider the application of biocomposites-based strategies for dental bone regeneration.

STUDY DESIGN

Research papers related to the topic, published over the last 20 years, were selected using the Web of Science, Pubmed, Scopus, and Google Scholar databases.

RESULTS

The strategies of monophasic, biphasic/multiphasic scaffolds, and biopolymer-based nanocomposite scaffolds containing nanomaterials compared with traditional methods used for bone regeneration, such as autografts, allografts, xenografts, and alloplasts are found to be superior because of their ability to overcome the issues (e.g., limited bone sources, pain, immune responses, high cost) related to the applications of the traditional methods.

CONCLUSIONS

In addition, additive manufacturing technologies were found to be highly advantageous for improving the efficacy of biocomposite scaffolds for treating dental bone defects.

Gelatin methacryloyl hydrogel as an injectable scaffold with multi-therapeutic effects to promote antimicrobial disinfection and angiogenesis for regenerative endodontics

Regenerative endodontics represents a paradigm shift in dental pulp therapy for necrotic young permanent teeth. However, there are still challenges associated with attaining maximum root canal disinfection while supporting angiogenesis and preserving resident stem cells viability and differentiation capacity. Here, we developed a hydrogel system by incorporating antibiotic-eluting fiber-based microparticles in gelatin methacryloyl (GelMA) hydrogel to gather antimicrobial and angiogenic properties while prompting minimum cell toxicity. Minocycline (MINO) or clindamycin (CLIN) was introduced into a polymer solution and electrospun into fibers, which were further cryomilled to attain MINO- or CLIN-eluting fibrous microparticles. To obtain hydrogels with multi-therapeutic effects, MINO- or CLIN-eluting microparticles were suspended in GelMA at distinct concentrations. The engineered hydrogels demonstrated antibiotic-dependent swelling and degradability while inhibiting bacterial growth with minimum toxicity in dental-derived stem cells. Notably, compared to MINO, CLIN hydrogels enhanced the formation of capillary-like networks of endothelial cells in vitro and the presence of widespread vascularization with functioning blood vessels in vivo. Our data shed new light onto the clinical potential of antibiotic-eluting gelatin methacryloyl hydrogel as an injectable scaffold with multi-therapeutic effects to promote antimicrobial disinfection and angiogenesis for regenerative endodontics.

Resorbable membrane design: In vitro characterization of silver doped-hydroxyapatite-reinforced XG/PEI semi-IPN composite

In this study, the production and characterization of silver-doped hydroxyapatite (AgHA) reinforced Xanthan gum (XG) and Polyethyleneimine (PEI) reinforced semi-interpenetrating polymer network (IPN) biocomposite, known to be used as bone cover material for therapeutic purposes in bone tissue, were performed. XG/PEI IPN films containing 2AgHA nanoparticles were produced by simultaneous condensation and ionic gelation. Characteristics of 2AgHA-XG/PEI nanocomposite film were evaluated by structural, morphological (SEM, XRD, FT-IR, TGA, TM, and Raman) and biological activity analysis (degradation, MTT, genotoxicity, and antimicrobial activity) techniques. In the physicochemical characterization, it was determined that 2AgHA nanoparticles were homogeneously dispersed in the XG/PEI-IPN membrane at high concentration and the thermal and mechanical stability of the formed film were high. The nanocomposites showed high antibacterial activity against Acinetobacter Baumannii (A.Baumannii), Staphylococcus aureus (S.aureus), and Streptococcus mutans (S.mutans). L929 exhibited good biocompatibility for fibroblast cells and was determined to support the formation of MCC cells. It was shown that a resorbable 2AgHA-XG/PEI composite material was obtained with a high degradation rate and 64% loss of mass at the end of the 7th day. Physico-chemically developed biocompatible and biodegradable XG-2AgHA/PEI nanocomposite semi-IPN films possessed an important potential for the treatment of defects in bone tissue as an easily applicable bone cover. Besides, it was noted that 2AgHA-XG/PEI biocomposite could increase cell viability, especially in dental-bone treatments for coating, filling, and occlusion.

Marine Biopolymers as Bioactive Functional Ingredients of Electrospun Nanofibrous Scaffolds for Biomedical Applications

Marine biopolymers, abundantly present in seaweeds and marine animals, feature diverse structures and functionalities, and possess a wide range of beneficial biological activities. Characterized by high biocompatibility and biodegradability, as well as unique physicochemical properties, marine biopolymers are attracting a constantly increasing interest for the development of advanced systems for applications in the biomedical field. The development of electrospinning offers an innovative technological platform for the production of nonwoven nanofibrous scaffolds with increased surface area, high encapsulation efficacy, intrinsic interconnectivity, and structural analogy to the natural extracellular matrix. Marine biopolymer-based electrospun nanofibrous scaffolds with multifunctional characteristics and tunable mechanical properties now attract significant attention for biomedical applications, such as tissue engineering, drug delivery, and wound healing. The present review, covering the literature up to the end of 2021, highlights the advancements in the development of marine biopolymer-based electrospun nanofibers for their utilization as cell proliferation scaffolds, bioadhesives, release modifiers, and wound dressings.

Development of Si doped nano hydroxyapatite reinforced bilayer chitosan nanocomposite barrier membranes for guided bone regeneration

Guided Bone Regeneration (GBR) is a widely used process for the treatment of periodontal defects to prevent the formation of surrounding soft tissue at the periodontal defect and to provide hard tissue regeneration. Recently GBR designs have focused on the development of resorbable natural polymer-based barrier membranes due to their biodegradability and excellent biocompatibility. The aim of this study is to fabricate a novel bilayer nanocomposite membrane with microporous sublayer composed of chitosan and Si doped nanohydroxyapatite particles (Si-nHap) and chitosan/PEO nanofiber upper layer. Bilayer membrane was designed to prevent epithelial and fibroblastic cell migration and growth impeding bone formation with its upper layer and to support osteogenic cell bioactivity at the defect site with its sublayer. Microporous and nanofiber layers were fabricated by using freeze-drying and electrospinning techniques respectively. The effect of Si-nHap content on the morphological, mechanical and physical properties of the composites were investigated using SEM, AFM, micro-Ct, compression test, water uptake capacity and enzymatic degradation study. Antimicrobial properties of nanocomposite membranes were investigated with tube dilution and disk diffusion methods. In vitro cytotoxicity of bilayer membranes was evaluated. Saos-2 and NIH/3T3 proliferation studies were carried out on each layer. In vitro bioactivity of Saos-2 and NIH/3T3 cells were evaluated with ALP activity and hydroxyproline content respectively. Results showed that Si-nHap incorporation enhanced the mechanical and physical properties as well as controlling biodegradability of the polymer matrix. Besides, Si-nHap loading induced the bioactivity of Saos-2 cells by enhancing cell attachment, spreading and biomineralization on the material surface. Thus, results supported that designed bilayer nanocomposite membranes can be used as a potential biomaterial for guided bone regeneration in periodontal applications.

Recent applications of electrical, centrifugal, and pressurised emerging technologies for fibrous structure engineering in drug delivery, regenerative medicine and theranostics

Advancements in technology and material development in recent years has led to significant breakthroughs in the remit of fiber engineering. Conventional methods such as wet spinning, melt spinning, phase separation and template synthesis have been reported to develop fibrous structures for an array of applications. However, these methods have limitations with respect to processing conditions (e.g. high processing temperatures, shear stresses) and production (e.g. non-continuous fibers). The materials that can be processed using these methods are also limited, deterring their use in practical applications. Producing fibrous structures on a nanometer scale, in sync with the advancements in nanotechnology is another challenge met by these conventional methods. In this review we aim to present a brief overview of conventional methods of fiber fabrication and focus on the emerging fiber engineering techniques namely electrospinning, centrifugal spinning and pressurised gyration. This review will discuss the fundamental principles and factors governing each fabrication method and converge on the applications of the resulting spun fibers; specifically, in the drug delivery remit and in regenerative medicine.

Insight on the effect of a piperonylic acid derivative on the crystallization process, melting behavior, thermal stability, optical and mechanical properties of poly(l-lactic acid)

A new piperonylic acid derivative (BPASD) was synthesized and evaluated as an organic nucleating agent for poly(l-lactic acid) (PLLA) via melt-crystallization; the other behaviors including cold-crystallization, melting process after crystallization, thermal stability in air atmosphere, and optical and mechanical properties of PLLA/BPASD samples were also investigated. The results of the melt-crystallization investigation showed that, in comparison to virgin PLLA, the BPASD could induce PLLA to crystallize in higher temperature region or at a faster cooling rate, suggesting that the BPASD as a heterogeneous nucleating agent could promote the crystallization of PLLA, but the melt-crystallization depended on the cooling rate, BPASD concentration, and the final melting temperature. With increasing of BPASD concentration, a shift to the lower temperature of cold-crystallization peak and decrease of crystallization enthalpy indicated that BPASD had an inhibition for the cold-crystallization of PLLA to some extent. The heating rate, crystallization temperature, the BPASD, and its concentration were critical factors to the melting process, and double-melting peaks appeared in heating were assigned to melting–recrystallization. Thermal decomposition behavior revealed that the addition of BPASD reduced the thermal stability of PLLA, but the interaction of PLLA and BPASD could prevent the decrease of the onset decomposition temperature. Further, the BPASD also decreased the light transmittance and elongation at the break of PLLA, but the tensile modulus and tensile strength of PLLA were enhanced.

Multi-Functional Electrospun Nanofibers from Polymer Blends for Scaffold Tissue Engineering

Electrospinning and polymer blending have been the focus of research and the industry for their versatility, scalability, and potential applications across many different fields. In tissue engineering, nanofiber scaffolds composed of natural fibers, synthetic fibers, or a mixture of both have been reported. This review reports recent advances in polymer blended scaffolds for tissue engineering and the fabrication of functional scaffolds by electrospinning. A brief theory of electrospinning and the general setup as well as modifications used are presented. Polymer blends, including blends with natural polymers, synthetic polymers, mixture of natural and synthetic polymers, and nanofiller systems, are discussed in detail and reviewed.

Manufacture and Property of Warp-Knitted Fabrics with Polylactic Acid Multifilament

This study investigates the properties of polylactic acid (PLA) multifilament and its warp-knitted fabrics. Multifilament properties were tested and compared with PET multifilament with different diameters. The 83.3 dtex PLA multifilament was used to knit the fabric, and the fabric properties before and after dyeing were studied. Results showed that the mechanical properties of PLA multifilament were comparable to those of PET. However, PLA had a higher heat shrinkage rate. The dyed PLA warp-knitted fabric has excellent color fastness. Due to the influence of temperature and dye particles during the dyeing process, the breaking strength, air permeability and moisture permeability of the fabric were decreased. On the contrary, the elongation at break, abrasion resistance, anti-pilling properties, drape and crochet value of the fabric were increased.