Berberine/Ag nanoparticle embedded biomimetic calcium phosphate scaffolds for enhancing antibacterial function

Comparison of the differentiation of ovine fetal bone-marrow mesenchymal stem cells towards osteocytes on chitosan/alginate/CuO-NPs and chitosan/alginate/FeO-NPs scaffolds

In the current study, the creation of a chitosan/alginate scaffold hydrogel with and without FeO-NPs or CuO-NPs was studied. From fetal ovine bone marrow mesenchymal stem cells (BM-MSCs) were isolated and cultivated. Their differentiation into osteocyte and adipose cells was investigated. Also, on the scaffolds, cytotoxicity and apoptosis were studied. To investigate the differentiation, treatment groups include: (1) BM-MSCs were plated in DMEM culture medium with high glucose containing 10% FBS and antibiotics (negative control); (2) BM-MSCs were plated in osteogenic differentiation medium (positive control); (3) positive control group + FeO-NPs, (4) positive control group + CuO-NPs; (5) BM-MSCs were plated in osteogenic differentiation medium on chitosan/alginate scaffold; (6) BM-MSCs were plated in osteogenic differentiation medium on chitosan/alginate/FeO-NPs scaffold; and (7) BM-MSCs were plated in osteogenic differentiation medium on chitosan/alginate/CuO-NPs scaffold. Alkaline phosphatase enzyme concentrations, mineralization rate using a calcium kit, and mineralization measurement by alizarin staining quantification were evaluated after 21 days of culture. In addition, qRT-PCR was used to assess the expression of the ALP, ColA, and Runx2 genes. When compared to other treatment groups, the addition of CuO-NPs in the chitosan/alginate hydrogel significantly increased the expression of the ColA and Runx2 genes (p < 0.05). However, there was no significant difference between the chitosan/alginate hydrogel groups containing FeO-NPs and CuO-NPs in the expression of the ALP gene. It appears that the addition of nanoparticles, in particular CuO-NPs, has made the chitosan/alginate scaffold more effective in supporting osteocyte differentiation.

DLP 3D printing of high-resolution root scaffold with bionic bioactivity and biomechanics for personalized bio-root regeneration

Digital light projection (DLP) printing of hydroxyapatite (HAp) bioceramic provides a promising strategy for fabrication of complex personalized bio-tooth root scaffold with high-resolution. However, it is still a challenge to fabricate bionic bio-tooth root with satisfied bioactivity and biomechanics. This research studied the HAp-based bioceramic scaffold with bionic bioactivity and biomechanics for personalized bio-root regeneration. Compared to natural decellularized dentine (NDD) scaffolds with unitary shape and restricted mechanical properties, those DLP printing bio-tooth roots with natural size, high precision appearance, excellent structure, and a smooth surface were successfully manufactured, which met various shape and structure requirements for personalized bio-tooth regeneration. Moreover, the bioceramic sintering at 1250 °C enhanced the physicochemical properties of HAp and exhibited good elastic modulus (11.72 ± 0.53 GPa), which was almost twice of early NDD (4.76 ± 0.75 GPa). To further improve the surface activity of sintered biomimetic, the nano-HAw (nano-hydroxyapatite whiskers) coating deposited by hydrothermal treatment increased the mechanical properties and surface hydrophilicity, which indicated positive effects on dental follicle stem cells (DFSCs)' proliferation and enhanced the DFSCs osteoblastic differentiation in vitro. Subcutaneous transplantation in nude mice and in-situ transplantation in rat alveolar fossa proved that the nano-HAw-containing scaffold could promote the DFSCs differentiate into periodontal ligament-like enthesis formation. In conclusion, by combining the optimized sintering temperature and modified nano-HAw interface through hydrothermal treatment, the DLP-printing of HAp-based bioceramic with favorable bioactivity and biomechanics is a promising candidate for personalized bio-root regeneration.

Can Differently Stabilized Silver Nanoparticles Modify Calcium Phosphate Precipitation?

Calcium phosphates (CaPs) composites with silver nanoparticles (AgNPs) attract attention as a possible alternative to conventional approaches to combating orthopedic implant-associated infections. Although precipitation of calcium phosphates at room temperatures was pointed out as an advantageous method for the preparation of various CaP-based biomaterials, to the best of our knowledge, no such study exists for the preparation of CaPs/AgNP composites. Motivated by this lack of data in this study we investigated the influence of AgNPs stabilized with citrate (cit-AgNPs), poly(vinylpyrrolidone) (PVP-AgNPs), and sodium bis(2-ethylhexyl) sulfosuccinate (AOT-AgNPs) in the concentration range 5-25 mg dm^-3 on the precipitation of CaPs. The first solid phase to precipitate in the investigated precipitation system was amorphous calcium phosphate (ACP). The effect of AgNPs on ACP stability was significant only in the presence of the highest concentration of AOT-AgNPs. However, in all precipitation systems containing AgNPs, the morphology of ACP was affected, as gel-like precipitates formed in addition to the typical chain-like aggregates of spherical particles. The exact effect depended on the type of AgNPs. After 60 min of reaction time, a mixture of calcium-deficient hydroxyapatite (CaDHA) and a smaller amount of octacalcium phosphate (OCP) formed. PXRD and EPR data point out that the amount of formed OCP decreases with increasing AgNPs concentration. The obtained results showed that AgNPs can modify the precipitation of CaPs and that CaPs properties can be fine-tuned by the choice of stabilizing agent. Furthermore, it was shown that precipitation can be used as a simple and fast method for CaP/AgNPs composites preparation which is of special interest for biomaterials preparation.

Complexes of Ag and ZnO nanoparticles with BBR for enhancement of gastrointestinal antibacterial activity through the impacts of size and composition

This study introduces the bioformulations of Ag/BBR and ZnO/BBR complexes against pathogenic bacteria in the gastrointestinal tract. Without the use of toxic reduction agents, Ag and ZnO NPs were prepared using an electrochemical method and then facially mixed with BBR solution to form Ag/BBR and ZnO/BBR complexes. BBR molecules are strongly conjugated with Ag and ZnO NPs through coordinated bonding and electrostatic interaction. As a result, the presence of BBR significantly influenced the nanoparticle growth, resulting in the formation of core/shell structured Ag/BBR and ZnO/BBR NPs with small particle sizes. The antibacterial test showed that BBR, Ag, or ZnO components all contributed to the increase of antibacterial ability of Ag/BBR and ZnO/BBR NPs against both methicillin-resistant Staphylococcus aureus (MRSA) and Salmonella enteritidis (S. enteritidis). The bactericidal ability of Ag/BBR and ZnO/BBR complexes against MRSA was exhibited even at a concentration of four-fold dilution (corresponding to 1.25 g L^-1 of BBR and 46.25 mg L^-1 of Ag) and two-fold dilution (corresponding to 2.5 g L^-1 of BBR and 10 mg L^-1 of ZnO), respectively, while that of the Ag/BBR complex against S. enteritidis showed at a concentration of two-fold dilution corresponding to 2.5 g L^-1 of BBR and 92.5 mg L^-1 of Ag. The results obtained in this study support that Ag/BBR and ZnO/BBR complexes can be potential therapeutic agents against gastrointestinal infections.

Enhanced osteogenesis and angiogenesis of biphasic calcium phosphate scaffold by synergistic effect of silk fibroin coating and zinc doping

Biphasic calcium phosphate (BCP) scaffold has been widely applied to bone regeneration because of its good biocompatibility and bone conduction property. However, the low mechanical strength and the lack of angiogenic and osteogenic induction properties have restricted its application in bone tissue regeneration. In this study, we combined zinc (Zn²⁺) doping and silk fibroin (SF) coating with expectation to enhance compressive strength, osteogenesis and angiogenesis of BCP scaffolds. The phase composition, morphology, porosity, compressive strength, in vitro degradation and cell behaviors were investigated systematically. Results showed that the scaffold coated with SF exhibited almost 3 times of compressive strength without compromising its porosity compared with the uncoated scaffold. Zn²⁺ doping and SF coating synergistically enhanced the alkaline phosphatase activity and osteogenesis-related genes expression of mouse bone mesenchymal stem cells (mBMSCs). Furthermore, SF coating notably improved the proliferation, cell viability and in vitro angiogenesis of human umbilical vein endothelial cells (HUVECs). This work provides a novel way to modify BCP scaffolds simultaneously with enhancing mechanical strength and biological properties.

Bioceramic-based scaffolds with antibacterial function for bone tissue engineering: A review

Bone defects caused by trauma, tumor, congenital abnormality and osteoarthritis, etc. have been substantially impacted the lives and health of human. Artificial bone implants, like bioceramic-based scaffolds, provide significant benefits over biological counterparts and are critical for bone repair and regeneration. However, it is highly probable that bacterial infections occur in the surgical procedures or on bioceramic-based scaffolds. Therefore, it is of great significance to obtain bioceramic-based scaffolds with integrative antibacterial and osteogenic functions for treating bone implant-associated infection and promoting bone repair. To fight against infection problems, bioceramic-based scaffolds with various antibacterial strategies are developed for bone repair and regeneration and also have made great progresses. This review summarizes recent progresses in bioceramic-based scaffolds with antibacterial function, which include drug-induced, ion-mediated, physical-activated and their combined antibacterial strategies according to specific antibacterial mechanism. Finally, the challenges and opportunities of antibacterial bioceramic-based scaffolds are discussed.

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Bioceramic-based scaffolds with antibacterial function (BSAF) are reviewed.

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BSAF have a great potential in treating bone infection and promoting bone repair.

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Antibacterial strategies of BSAF include drug, ion, physical and combined ways.

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The combined strategy may be the optimal approach in fighting bone infection.

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Limitations, challenges and perspectives of BSAF are discussed.

Scaffolds in the microbial resistant era: Fabrication, materials, properties and tissue engineering applications

Due to microbial infections dramatically affect cell survival and increase the risk of implant failure, scaffolds produced with antimicrobial materials are now much more likely to be successful. Multidrug-resistant infections without suitable prevention strategies are increasing at an alarming rate. The ability of cells to organize, develop, differentiate, produce a functioning extracellular matrix (ECM) and create new functional tissue can all be controlled by careful control of the extracellular microenvironment. This review covers the present state of advanced strategies to develop scaffolds with antimicrobial properties for bone, oral tissue, skin, muscle, nerve, trachea, cardiac and other tissue engineering applications. The review focuses on the development of antimicrobial scaffolds against bacteria and fungi using a wide range of materials, including polymers, biopolymers, glass, ceramics and antimicrobials agents such as antibiotics, antiseptics, antimicrobial polymers, peptides, metals, carbon nanomaterials, combinatorial strategies, and includes discussions on the antimicrobial mechanisms involved in these antimicrobial approaches. The toxicological aspects of these advanced scaffolds are also analyzed to ensure future technological transfer to clinics. The main antimicrobial methods of characterizing scaffolds’ antimicrobial and antibiofilm properties are described. The production methods of these porous supports, such as electrospinning, phase separation, gas foaming, the porogen method, polymerization in solution, fiber mesh coating, self-assembly, membrane lamination, freeze drying, 3D printing and bioprinting, among others, are also included in this article. These important advances in antimicrobial materials-based scaffolds for regenerative medicine offer many new promising avenues to the material design and tissue-engineering communities.

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Antibacterial, antifungal and antibiofilm scaffolds.

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Antimicrobial scaffold fabrication techniques.

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Antimicrobial biomaterials for tissue engineering applications.

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Antimicrobial characterization methods of scaffolds.

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Bone, oral tissue, skin, muscle, nerve, trachea, cardiac, among other applications.

Antibacterial Honeycomb Scaffolds for Achieving Infection Prevention and Bone Regeneration

Surgical site infection (SSI) is a severe complication associated with orthopedic bone reconstruction. For both infection prevention and bone regeneration, the framework surface of osteoconductive and bioresorbable scaffolds must be locally modified by minimum antibacterial substances, without sacrificing the osteoconductivity of the scaffold framework. In this study, we fabricated antibacterial honeycomb scaffolds by replacing carbonate apatite, which is the main component of the scaffold, with silver phosphate locally on the scaffold surface via dissolution-precipitation reactions. When the silver content was 9.9 × 10^-4 wt %, the honeycomb scaffolds showed antibacterial activity without cytotoxicity and allowed cell proliferation, differentiation, and mineralization. Furthermore, the antibacterial honeycomb scaffolds perfectly prevented bacterial infection in vivo in the presence of methicillin-resistant Staphylococcus aureus, formed new bone at 2 weeks after surgery, and were gradually replaced with a new bone. Thus, the antibacterial honeycomb scaffolds achieved both infection prevention and bone regeneration. In contrast, severe infection symptoms, including abscess formation, osteolytic lesions, and inflammation, occurred 2 weeks after surgery when honeycomb scaffolds without silver phosphate modification were implanted. Nevertheless, the unmodified honeycomb scaffolds eliminated bacteria and necrotic bone through their scaffold channels, resulting in symptom improvement and bone formation. These results suggest that the honeycomb structure is inherently effective in hindering bacterial growth. This novel insight may contribute to the development of antibacterial scaffolds. Moreover, our modification method is useful for providing antibacterial activity to various biomaterials.

Silk Polymers and Nanoparticles: A Powerful Combination for the Design of Versatile Biomaterials

Silk fibroin (SF) is a natural protein largely used in the textile industry but also in biomedicine, catalysis, and other materials applications. SF is biocompatible, biodegradable, and possesses high tensile strength. Moreover, it is a versatile compound that can be formed into different materials at the macro, micro- and nano-scales, such as nanofibers, nanoparticles, hydrogels, microspheres, and other formats. Silk can be further integrated into emerging and promising additive manufacturing techniques like bioprinting, stereolithography or digital light processing 3D printing. As such, the development of methodologies for the functionalization of silk materials provide added value. Inorganic nanoparticles (INPs) have interesting and unexpected properties differing from bulk materials. These properties include better catalysis efficiency (better surface/volume ratio and consequently decreased quantify of catalyst), antibacterial activity, fluorescence properties, and UV-radiation protection or superparamagnetic behavior depending on the metal used. Given the promising results and performance of INPs, their use in many different procedures has been growing. Therefore, combining the useful properties of silk fibroin materials with those from INPs is increasingly relevant in many applications. Two main methodologies have been used in the literature to form silk-based bionanocomposites: in situ synthesis of INPs in silk materials, or the addition of preformed INPs to silk materials. This work presents an overview of current silk nanocomposites developed by these two main methodologies. An evaluation of overall INP characteristics and their distribution within the material is presented for each approach. Finally, an outlook is provided about the potential applications of these resultant nanocomposite materials.

Hyaluronic acid as a bioactive component for bone tissue regeneration: Fabrication, modification, properties, and biological functions

Hyaluronic acid (HA) is widely distributed in the human body, and it is heavily involved in many physiological functions such as tissue hydration, wound repair, and cell migration. In recent years, HA and its derivatives have been widely used as advanced bioactive polymers for bone regeneration. Many medical products containing HA have been developed because this natural polymer has been proven to be nontoxic, noninflammatory, biodegradable, and biocompatible. Moreover, HA-based composite scaffolds have shown good potential for promoting osteogenesis and mineralization. Recently, many HA-based biomaterials have been fabricated for bone regeneration by combining with electrospinning and 3D printing technology. In this review, the polymer structures, processing, properties, and applications in bone tissue engineering are summarized. The challenges and prospects of HA polymers are also discussed.