Biomineralization of bone-like hydroxyapatite to upgrade the mechanical and osteoblastic performances of poly(lactic acid) scaffolds

Recent advances of bone tissue engineering: carbohydrate and ceramic materials, fundamental properties and advanced biofabrication strategies ‒ a comprehensive review

Bone is a dynamic tissue that can always regenerate itself through remodeling to maintain biofunctionality. This tissue performs several vital physiological functions. However, bone scaffolds are required for critical-size damages and fractures, and these can be addressed by bone tissue engineering. Bone tissue engineering (BTE) has the potential to develop scaffolds for repairing critical-size damaged bone. BTE is a multidisciplinary engineered scaffold with the desired properties for repairing damaged bone tissue. Herein, we have provided an overview of the common carbohydrate polymers, fundamental structural, physicochemical, and biological properties, and fabrication techniques for bone tissue engineering. We also discussed advanced biofabrication strategies and provided the limitations and prospects by highlighting significant issues in bone tissue engineering. There are several review articles available on bone tissue engineering. However, we have provided a state-of-the-art review article that discussed recent progress and trends within the last 3-5 years by emphasizing challenges and future perspectives.

Tetracalcium phosphate/porous iron synergistically improved the mechanical, degradation and biological properties of polylactic acid scaffolds

Synergistically improving the mechanical and degradable properties of polylactic acid (PLA) scaffolds and endowing them with bioactivity are urgent problems to be solved in deepening their application in tissue engineering. In this work, tetracalcium phosphate (TTCP) and porous iron (pFe) were compounded by stirring and vacuum negative pressure, and then they were blended with polylactic acid and a porous scaffold (named TTCP@pFe/PLA) was prepared by selective laser sintering. On the one hand, molten polylactic acid penetrates the pores of porous iron to form an interlocking network, thereby achieving mechanical strengthening. On the other hand, the alkaline environment generated by the dissolution of tetracalcium phosphate can effectively catalyze the hydrolysis of polylactic acid to accelerate the degradation. Meanwhile, the dissolution of tetracalcium phosphate forms a local calcium-rich microenvironment, which rapidly induces apatite formation, that is, confers bioactivity on scaffolds. As a result, the TTCP@pFe/PLA scaffold exhibited a notable enhancement in mechanical strength, being 2.2 times stronger compared to the polylactic acid scaffold. More importantly, MC3T3E1 cells exhibit good adhesion, stretching, and proliferation on the composite scaffold, demonstrating good cytocompatibility. All these good properties of the TTCP@pFe/PLA scaffold indicate that it has potential applications as a novel alternative in bone tissue regeneration.

Incorporating bioactive glass nanoparticles in silk fibroin/bacterial nanocellulose composite scaffolds improves their biological and osteogenic properties for bone tissue engineering applications

Blend polymers composed of natural polymers are a ubiquitous biomaterial class due to their suitable mechanical and biological characterization. In the present study, composite scaffolds based on bacterial cellulose (BC)/silk fibroin (SF) with bioactive glass nanoparticles (BGNPs) were developed to enhance osteogenesis in human adipose derived stem cells (hASCs). The scanning electron microscopy (SEM) results of BGNPs indicated a spherical morphology and size ranging from 15 to 30 nm. The presence of BC and BGNPs reduced the pore diameter of SF scaffolds to about 210 ± 10 μm and 205 ± 10 μm, respectively, while increasing their compressive strength and compressive modulus. FTIR analyses proved the presence of BGNPs, BC and SF in the scaffolds. Flow cytometry data confirmed the surface markers for hASCs. The results also showed that BC and BGNPs addition to BC/SF scaffolds decreased degradation and swelling rate. The gene expression (Runx2, alkaline phosphatase and osteocalcin) studies signified the osteogenic potential of BGNPs in BC/SF scaffolds on hASCs. Eventually, the increased cell adhesion, viability and differentiation in the BC/SF and BC/SF/BGNPs composite scaffolds drawn from MTT, SEM, Alizarin red staining and alkaline phosphatase activity confirmed that these scaffolds promise to serve as a therapeutic candidate for bone defects.

Stable nanoscale sea-island structure of biobased polyamide 56/poly (butylene adipate-co-terephthalate) blends compatibilized by interfacial hyperbranched structure: Toward biobased polymer blends with ultrahigh toughness

Developing biobased materials is a considerably effective approach to save fossil resources and reduce emissions. Biobased polyamide 56 (PA56) is an excellent engineering material, but it has low toughness. Herein, to enhance the toughness of PA56, an ultra-tough biodegradable material, i.e., poly (butylene adipate-co-terephthalate) (PBAT) was introduced into PA56. Moreover, a self-synthesized epoxy-terminated hyperbranched polyester (EHBP) was used to improve the compatibility of the blended materials. The results of differential scanning calorimetry and Fourier-transform infrared spectroscopy indicated that the epoxide group of EHBP could react with PA56 and PBAT to form a block-like polymer structure and limit the crystallization behavior of the blends. The scanning electron microscopy results show that the addition of EHBP considerably reduced the dispersed-phase size in the blends, forming a nanoscale island structure. Moreover, the hydrogen bonds formed between EHBP and PA56/PBAT enhanced the intermolecular interaction between the two materials. Thus, PA56 blends with ultrahigh toughness were successfully prepared. The prepared PA56/PBAT/EHBP blend exhibited a notch impact strength of 20.71 kJ/m2 and a breaking elongation of 38.3 %, which represent increases of 427.3 % and 252.8 %, respectively, compared with those of pure PA56. Thus, the proposed method is suitable for toughening PA56 and broadening its applications.

Self-Charging, Breathable, and Antibacterial Poly(lactic acid) Nanofibrous Air Filters by Surface Engineering of Ultrasmall Electroactive Nanohybrids

Despite the great promise in the development of biodegradable and ecofriendly air filters by electrospinning of poly(lactic acid) (PLA) nanofibrous membranes (NFMs), the as-electrospun PLA nanofibers are generally characterized by poor electroactivity and smooth surface, challenging the exploitation of electrostatic adsorption and physical interception that are in need for efficient removal of pathogens and particulate matters (PMs). Herein, a combined "electrospinning-electrospray" strategy was disclosed to functionalize the PLA nanofibers by direct anchoring of highly dielectric BaTiO3@ZIF-8 nanohybrids (BTO@ZIF-8), conferring simultaneous promotion of surface roughness, electret properties (surface potential as high as 7.5 kV), and self-charging capability (∼190% increase in tribo-output voltage compared to that of pure PLA). Benefiting from the well-tailored morphology and increased electroactivity, the electrospun-electrosprayed PLA/BTO@ZIF-8 exhibited excellent PM-capturing performance (up to 96.54% for PM0.3 and 99.49% for PM2.5) while providing desirable air resistance (only 87 Pa at 32 L/min) due primarily to the slip flow of air molecules over the nanohybrid protrusions. This was accompanied by excellent antibacterial properties (99.9% inhibition against both Staphylococcus aureus and Escherichia coli), arising presumably from the synergistic effects of enhanced reactive oxygen species (ROS) generation, plentiful ion release, and surface charges. Our proposed strategy opens up pathways to afford exceptional combination of high-efficiency and low-resistance filtration, excellent antibacterial performance, and mechanical robustness without sacrificing the biodegradation profiles of PLA NFMs, holding potential implications for efficient and long-term healthcare.

Osseointegration enhancement by controlling dispersion state of carbonate apatite in polylactic acid implant

Osteoconductive ceramics (OCs) are often used to endow polylactic acid (PLA) with osseointegration ability. Conventionally, OC powder is dispersed in PLA. However, considering cell attachment to the implant, OCs may be more favorable when they exist in the form of aggregations, such as granules, and are larger than the cells rather than being dispersed like a powder. In this study, to clarify the effects of the dispersion state of OCs on the osseointegration ability, carbonate apatite (CAp), a bone mineral analog that is osteoconductive and bioresorbable, powder-PLA (P-PLA), and CAp granule-PLA (G-PLA) composite implants were fabricated via thermal pressing. The powder and granule sizes of CAp were approximately 1 and 300-600 µm, respectively. G-PLA exhibited a higher water wettability and released calcium and phosphate ions faster than P-PLA. When cylindrical G-PLA, P-PLA, and PLA were implanted in rabbit tibial bone defects, G-PLA promoted bone maturation compared to P-PLA and pure PLA. Furthermore, G-PLA bonded directly to the host bone, whereas P-PLA bonded across the osteoid layers. Consequently, the bone-to-implant contact of G-PLA was 1.8- and 5.6-fold higher than those of P-PLA and PLA, respectively. Furthermore, the adhesive shear strength of G-PLA was 1.9- and 3.0-fold higher than those of P-PLA and PLA, respectively. Thus, G-PLA achieved earlier and stronger osseointegration than P-PLA or PLA. The findings of this study highlight the significance of the state of dispersion of OCs in implants as a novel strategy for material development.

A new composite fabricated from hydroxyapatite, gelatin-MgO microparticles, and compatibilized poly(butylene succinate) with osteogenic functionality

In this study, thermally processed recycled fish teeth (FT) and fish scales, magnesium oxide (MgO), and biobased polyesters were fabricated into new bioactive and environmentally friendly composites. The magnesium oxide was encapsulated into laboratory-made fish scale-derived gelatin to form gelatin-MgO microparticles. Hydroxyapatite (HA) and gelatin were obtained by heat-treating FTs and fish scales, respectively. Compatibilized poly(butylene succinate) (CPBS), i.e., poly(butylene succinate) (PBS) to which had been added acrylic acid-grafted PBS (PBS-g-AA) compatibilizer, was combined with HA/gelatin-MgO (GHA) to form CPBS/GHA composites. The structure and tensile properties of the composites were investigated. The CPBS/GHA composites improved the adhesion and proliferation of osteoblast cells. Osteoblast growth, osteoclast growth inhibition, and the antibacterial effect of CPBS/GHA composites were primarily due to the slow release of magnesium ions into the environment from the gelatin-MgO microparticles. Higher levels of calcium and phosphorus species were observed for various PBS/HA and CPBS/GHA composites immersed in simulated body fluid. Mineralization measurements indicated that calcium and phosphate ions precipitated in osteoblasts placed on PBS/HA and CPBS/GHA composites. The study successfully developed a new composite material containing 5 wt% gelatin/MgO (phr), CPBS/HA 10 wt% and 1.0 % gelatin/MgO (an optimum formula of MgO). This composite exhibited superior tensile strength, antibacterial effect, osteoclast growth enhancement, and osteoclast growth reduction. These results suggest that the composites may facilitate the formation of new bone formation in vivo. The CPBS/GHA composites displayed good bone tissue repair ability in engineering applications.

Nanopatterned Electroactive Polylactic Acid Nanofibrous MOFilters for Efficient PM0.3 Filtration and Bacterial Inhibition

Biodegradable polylactic acid (PLA) nanofibrous membranes (NFMs) hold great potential to address the increasing airborne particulate matter (PM) and dramatic accumulation of plastic/microplastic pollution. However, the field of PLA NFM-based filters is still in its infancy, frequently dwarfed by the bottlenecks regarding relatively low surface activity, poor electroactivity, and insufficient PM capturing mechanisms. This effort discloses a microwave-assisted approach to minute-level synthesis of dielectric ZIF-8 nanocrystals with high specific surface area (over 1012 m2/g) and ultrasmall size (∼240 nm), which were intimately anchored onto PLA nanofibers (PLA@ZIF-8) by a combined "electrospinning-electrospray" strategy. This endowed the PLA@ZIF-8 NFMs with largely increased electroactivity in terms of elevated dielectric coefficient (an increase of 202%), surface potential (up to 5.8 kV), and triboelectric properties (output voltage of 30.8 V at 10 N, 0.5 Hz). Given the profound control over morphology and electroactivity, the PLA@ZIF-8 NFMs exhibited efficient filtration of PM0.3 (97.1%, 85 L/min) with a decreased air resistance (592.5 Pa), surpassing that of the pure PLA counterpart (88.4%, 650.9 Pa). This was essentially ascribed to realization of multiple filtration mechanisms for PLA@ZIF-8 NFMs, including enhanced physical interception, polar interactions, and electrostatic adsorption, and the unique self-charging function triggered by airflow vibrations. Moreover, perfect antibacterial performance was achieved for PLA@ZIF-8, showing ultrahigh inhibition rates of 99.9 and 100% against E. coli and S. aureus, respectively. The proposed hierarchical structuring strategy, offering the multifunction integration unattainable with conventional methods, may facilitate the development of biodegradable long-term air filters.

Preparation and characterization of novel poly (lactic acid)/calcium oxide nanocomposites by electrospinning as a potential bone tissue scaffold

Calcium oxide nanoparticles (n-CaO) ca. 22 nm were obtained from eggshell waste. The n-CaO was incorporated into the PLA matrix in 10 and 20 wt% of filler content by electrospinning process to get PLA/n-CaO fibers with homogenous morphology and diameter as a potential use in scaffold for bone tissue regeneration. The incorporation of n-CaO into PLA modifies the mechanical properties, having a reinforcement effect on the matrix. The Young modulus for PLA/n-CaO nanocomposites increased between 122 and 138 % concerning neat PLA fibers, showing a more rigid behavior. The PLA/n-CaO nanocomposite fibers showed in vitro bioactivity, capable of inducing the precipitation of hydroxyapatite (HA) layer in the fiber surface after seven days in SBF solution. The biocidal and biological properties of PLA/n-Cao with 20 wt% showed a 30 % reduction in bacterial viability against S. aureus and 11 % against E. coli after 6 h of bacterial exposure. Furthermore, the fibers did not show a cytotoxic effect on the bone marrow ST-2 cell line, allowing cell adhesion and proliferation in the RPMI medium. The PLA/n-CaO with 20 wt% of nanoparticles showed a higher capacity to promote osteogenic differentiation, significantly increasing the alkaline phosphatase (ALP) expression after seven days compared to PLA and cell control. The in vivo analysis corroborated the biocompatibility of the prepared scaffolds; the presence of n-CaO in PLA reduced the formation of fibrous encapsulation of the material, improving the healing process. These results validated using n-CaO to enhance the functionality of polymer matrices as a PLA, bringing bioactive, biocide, and biocompatible properties, opening a new and interesting route to develop new biomaterials as a scaffold for bone tissue engineering.

Biomimetic Nacre-like Hydroxyapatite/Polymer Composites for Bone Implants

One of the most ambitious goals for bone implants is to improve bioactivity, incapability, and mechanical properties; to reduce the need for further surgery; and increase efficiency. Hydroxyapatite (HA), the main inorganic component of bones and teeth, has high biocompatibility but is weak and brittle material. Cortical bone is composed of 70% calcium phosphate (CaP) and 30% collagen and forms a complex hierarchical structure with anisotropic and lamellar microstructure (osteons) which makes bone a light, strong, tough, and durable material that can support large loads. However, imitation of concentric lamellar structure of osteons is difficult to achieve in fabrication. Nacre from mollusk shells with layered structures has now become the archetype of the natural "model" for bio-inspired materials. Incorporating a nacre-like layered structure into bone implants can enhance their mechanical strength, toughness, and durability, reducing the risk of implant catastrophic failure or fracture. The layered structure of nacre-like HA/polymer composites possess high strength, toughness, and tunable stiffness which matches that of bone. The nacre-like HA/polymer composites should also possess excellent biocompatibility and bioactivity which facilitate the bonding of the implant with the surrounding bone, leading to improved implant stability and long-term success. To achieve this, a bi-directional freeze-casting technique was used to produce elongated lamellar HA were further densified and infiltrated with polymer to produce nacre-like HA/polymer composites with high strength and fracture toughness. Mechanical characterization shows that increasing the ceramic fractions in the composite increases the density of the mineral bridges, resulting in higher flexural and compressive strength. The nacre-like HA/(methyl methacrylate (MMA) + 5 wt.% acrylic acid (AA)) composites with a ceramic fraction of 80 vol.% showed a flexural strength of 158 ± 7.02 MPa and a Young's modulus of 24 ± 4.34 GPa, compared with 130 ± 5.82 MPa and 19.75 ± 2.38 GPa, in the composite of HA/PMMA, due to the higher strength of the polymer and the interface of the composite. The fracture toughness in the composition of 5 wt.% PAA to PMMA improves from 3.023 ± 0.98 MPa·m1/2 to 5.27 ± 1.033 MPa·m1/2 by increasing the ceramic fraction from 70 vol.% to 80 vol.%, respectively.

Bioelectret poly(lactic acid) membranes with simultaneously enhanced physical interception and electrostatic adsorption of airborne PM0.3

Traditional polymeric fibrous membranes have been extensively used to reduce the health risks caused by airborne particulate matter (PM), leading to the dramatically increasing pollution of plastics and microplastics. Although great efforts have been made to develop poly(lactic acid) (PLA)-based membrane filters, they are frequently dwarfed by their relatively poor electret properties and electrostatic adsorptive mechanisms. To resolve this dilemma, a bioelectret approach was proposed in this work, strategically involving the bioinspired adhesion of dielectric hydroxyapatite nanowhiskers as a biodegradable electret to promote the polarization properties of PLA microfibrous membranes. In addition to significant improvements in tensile properties, the incorporation of hydroxyapatite bioelectret (HABE) enabled remarkable increase in the removal efficiencies of ultrafine PM_0.3 in a high-voltage electrostatic field (10 and 25 kV). This was exemplified by the largely increased filtering performance (69.75%, 23.1 Pa) for PLA membranes loaded with 10 wt% HABE at the normal airflow rate (32 L/min) compared to the pristine PLA counterpart (32.89%, 7.2 Pa). Although the filtration efficiency of PM_0.3 for the counterpart dramatically decreased to 21.6% at 85 L/min, the increment was maintained at nearly 196% for the bioelectret PLA, while an ultralow pressure drop (74.5 Pa) and high humidity resistance (RH 80%) were achieved. The unusual property combination were ascribed to the HABE-enabled realization of multiple filtration mechanisms, including the simultaneous enhancement of physical interception and electrostatic adsorption. The significant filtration applications, unattainable with conventional electret membranes, demonstrate the bioelectret PLA as a promising biodegradable platform that allows high filtration properties and humidity resistance.

Electroactive, Antibacterial, and Biodegradable Poly(lactic acid) Nanofibrous Air Filters for Healthcare

Poly(lactic acid) (PLA)-based nanofibrous membranes (NFMs) hold great potential in the field of biodegradable filters for air purification but are largely limited by the relatively low electret properties and high susceptibility to bacteria. Herein, we disclosed a facile approach to the fabrication of electroactive and antibacterial PLA NFMs impregnated with a highly dielectric photocatalyst. In particular, the microwave-assisted doping (MAD) protocol was employed to yield Zn-doped titanium dioxide (Zn-TIO), featuring the well-defined anatase phase, a uniform size of ∼65 nm, and decreased band gap (3.0 eV). The incorporation of Zn-TIO (2, 6, and 10 wt %) into PLA gave rise to a significant refinement of the electrospun nanofibers, decreasing from the highest diameter of 581 nm for pure PLA to the lowest value of 264 nm. More importantly, dramatical improvements in the dielectric constants, surface potential, and electret properties were simultaneously achieved for the composite NFMs, as exemplified by a nearly 94% increase in surface potential for 3-day-aged PLA/Zn-TIO (90/10) compared with that of pure PLA. The well regulation of morphological features and promotion of electroactivity contributed to a distinct increase in the air filtration performance, as demonstrated by 98.7% filtration of PM_0.3 with the highest quality factor of 0.032 Pa^-1 at the airflow velocity of 32 L/min for PLA/Zn-TIO (94/6), largely surpassing pure PLA (89.4%, 0.011 Pa^-1). Benefiting from the effective generation of reactive radicals and gradual release of Zn²⁺ by Zn-TIO, the electroactive PLA NFMs were ready to profoundly inactivate Escherichia coli and Staphylococcus epidermidis. The exceptional combination of remarkable electret properties and excellent antibacterial performance makes the PLA membrane filters promising for healthcare.

Bioelectrets in Electrospun Bimodal Poly(lactic acid) Fibers: Realization of Multiple Mechanisms for Efficient and Long-Term Filtration of Fine PMs

Despite the great potential in fabrication of biodegradable and eco-friendly air filters by electrospinning poly(lactic acid) (PLA) membranes, the filtering performance is frequently dwarfed by inadequate physical sieving or electrostatic adsorption mechanisms to capture airborne particulate matters (PMs). Here, using the parallel spinning approach, the unique micro/nanoscale architecture was established by conjugation of neighboring PLA nanofibers, creating bimodal fibers in electrospun PLA membranes for the enhanced slip effect to significantly reduce the air resistance. Moreover, the bone-like nanocrystalline hydroxyapatite bioelectret (HABE) was exploited to enhance the dielectric and polarization properties of electrospun PLA, accompanied by the controlled generation of junctions induced by the microaggregation of HABE (10-30 wt %). The incorporated HABE was supposed to orderly align in the applied E-field and largely promote the charging capability and surface potential, gradually increasing to 7.2 kV from the lowest level of 2.5 kV for pure PLA. This was mainly attributed to HABE-induced orientation of PLA backbone chains and C═O dipoles, as well as the interfacial charges trapped at the interphases of HABE-PLA and crystalline region-amorphous PLA. Given the multiple capturing mechanisms, the micro/nanostructured PLA/HABE membranes were characterized by excellent and sustainable filtering performance, e.g., the filtration efficiency of PM_0.3 was promoted from 59.38% for pure PLA to 94.38% after addition of 30 wt % HABE at a moderate airflow capacity of 32 L/min and from 30.78 to 83.75% at the highest level of 85 L/min. It is of interest that the pressure drop was significantly decreased, mainly arising from the slip effect between the ultrafine nanofibers and conjugated microfibers. The proposed combination of the nanostructured electret and the multistructuring strategy offers the function integration of efficient filtration and low resistance that are highly useful to pursue fully biodegradable filters.

Toward ultra-tough and heat-resistant biodegradable polylactide/core-shell rubber blends by regulating the distribution of rubber particles with stereocomplex crystallites

Ultra-tough and heat-resistant poly(l-lactide)/core-shell rubber (PLLA/CSR) blends were fabricated by utilizing stereocomplex (SC) crystallites to effectively regulate the CSR distribution in PLLA matrix. Linear and 3-11 armed poly(d-lactide)s (PDLAs) were synthesized and then melt-mixed with PLLA/CSR blend. Interestingly, the incorporated PDLA chains could collaborate with PLLA chains to form dense SC crystallites network in PLLA/PDLA/CSR blends, thus inducing the CSR particles to transform from uniform distribution structure to network-like structure. With increasing the PDLA arm numbers, the size of CSR clusters in the network-like structure first increased and then decreased, and the continuity of the network-like structure first remained at a high level and then decreased obviously. The formation of CSR network-like structure could remarkably improve the impact strength of PLLA/PDLA/CSR blends without deteriorating their strength and modulus (compared with PLLA/CSR blend), and the CSR network-like structure with larger-sized CSR clusters and higher continuity could help obtain higher impact strength (78.3 kJ/m²). Moreover, the heat resistance of PLLA/PDLA/CSR blends could also be significantly improved (the highest Vicat softening temperature was 131 °C) by the SC crystallites network and CSR network-like structure. This work provides an effective strategy for controlling the rubber network-like morphology and thereby preparing high-performance PLLA materials.

Vapor-Induced Pore-Forming Atmospheric-Plasma-Sprayed Zinc-, Strontium-, and Magnesium-Doped Hydroxyapatite Coatings on Titanium Implants Enhance New Bone Formation-An In Vivo and In Vitro Investigation

OBJECTIVES

Titanium implants are regarded as a promising treatment modality for replacing missing teeth. Osteointegration and antibacterial properties are both desirable characteristics for titanium dental implants. The aim of this study was to create zinc (Zn)-, strontium (Sr)-, and magnesium (Mg)-multidoped hydroxyapatite (HAp) porous coatings, including HAp, Zn-doped HAp, and Zn-Sr-Mg-doped HAp, on titanium discs and implants using the vapor-induced pore-forming atmospheric plasma spraying (VIPF-APS) technique.

METHODS

The mRNA and protein levels of osteogenesis-associated genes such as collagen type I alpha 1 chain (COL1A1), decorin (DCN), osteoprotegerin (TNFRSF11B), and osteopontin (SPP1) were examined in human embryonic palatal mesenchymal cells. The antibacterial effects against periodontal bacteria, including Porphyromonas gingivalis and Prevotella nigrescens, were investigated. In addition, a rat animal model was used to evaluate new bone formation via histologic examination and micro-computed tomography (CT).

RESULTS

The ZnSrMg-HAp group was the most effective at inducing mRNA and protein expression of TNFRSF11B and SPP1 after 7 days of incubation, and TNFRSF11B and DCN after 11 days of incubation. In addition, both the ZnSrMg-HAp and Zn-HAp groups were effective against P. gingivalis and P. nigrescens. Furthermore, according to both in vitro studies and histologic findings, the ZnSrMg-HAp group exhibited the most prominent osteogenesis and concentrated bone growth along implant threads.

SIGNIFICANCE

A porous ZnSrMg-HAp coating using VIPF-APS could serve as a novel technique for coating titanium implant surfaces and preventing further bacterial infection.

Self-Prepared Hyaluronic Acid/Alkaline Gelatin Composite with Nano-Hydroxyapatite and Bone Morphogenetic Protein for Cranial Bone Formation

New bone-forming substitute materials are highly useful in dental implantology. The purpose of this study was to prepare cross-linked hyaluronic acid (cHLA)/cross-linked alkaline gelatin (cAG)/nano-hydroxyapatite (nHAp)/bone morphogenic protein (BMP) constructs; and evaluate their bone-forming capabilities in rat cranial bone defects. The cHLA and cAG liquids processed with an epoxy cross-linker were blended with a 3:1 volume ratio, followed by freeze-drying. The dry composites were further infiltrated with water containing nHAp only (BMP (−)) or with water containing nHAp and BMP (BMP (+)). Prepared wet constructs (BMP (−) and BMP (+)) were implanted in rat cranial bone defects, while defects only were also made, and animals were fed for 8 weeks, followed by subsequent soft X-ray measurements and histological observations. The X-ray results showed that BMP (+) constructs disappeared, though caused inward extension of peripherical bone from defect edges with an increase in length of approximately 24%, larger than those of BMP (−) constructs and defect only with approximately 17% and 8% increments, respectively (p < 0.05). Histological observations of BMP (+) construct samples clearly indicated active bone extension consisting of an array of island-like bones. It was concluded that cHLA/cAG/nHAp/BMP could be used as novel bone-substitute materials.