An In Vitro Macrophage Response Study of Silk Fibroin and Silk Fibroin/Nano-Hydroxyapatite Scaffolds for Tissue Regeneration Application.

In recent years, silk fibroin (SF) has been incorporated with low crystallinity nanohydroxyapatite (nHA) as a scaffold for various tissue regeneration applications due to the mechanical strength of SF and osteoconductive properties of nHA. However, currently, there is a lack of understanding of the immune response toward the degradation products of SF with nHA composite after implantation. It is known that particulate fragments from the degradation of a biomaterial can trigger an immune response. As the scaffold is made of degradable materials, the degradation products may contribute to the inflammation. Therefore, in this study, the effects of the enzymatic degradation of the SF/nHA scaffold on macrophage response were investigated in comparison to the control SF scaffold. Since the degradation products of a scaffold can influence macrophage polarization, it can be hypothesized that as the SF and SF/nHA scaffolds were degraded in vitro using protease XIV solution, the degradation products can contribute to the polarization of THP-1-derived macrophages from pro-inflammatory M1 to anti-inflammatory M2 phenotype. The results demonstrated that the initial (day 1) degradation products of the SF/nHA scaffold elicited a pro-inflammatory response, while the latter (day 24) degradation products of the SF/nHA scaffold elicited an anti-inflammatory response. Moreover, the degradation products from the SF scaffold elicited a higher anti-inflammatory response due to the faster degradation of the SF scaffold and a higher amino acid concentration in the degradation solution. Hence, this paper can help elucidate the contributory effects of the degradation products of SF and SF/nHA scaffolds on macrophage response and provide greater insights into designing silk-based biomaterials with tunable degradation rates that can modulate macrophage response for future tissue regeneration applications.

Evaluating various properties of nanohydroxyapatite synthesized from eggshells and dual-doped with Si4+ and Zn2+: An in vitro study.

Background: This study aimed to evaluate morphological, chemical and biocompatible properties of nanohydroxyapatite (N-HA) synthesized from eggshells and dual-doped with Si4+ and Zn2+. Methods: In the current study, N-HA was synthesized from chicken eggshells using the wet chemical precipitation method and doped with Si4+ and Zn2+. The physical assessment was carried out using field emission scanning electron microscopy (FE-SEM), energy dispersive X-ray (EDX) analysis, and X-ray diffraction (XRD) analysis. Crystal size was calculated using the Scherrer equation. Cytotoxicity was studied in vitro using the MTT (3-(4,5-Dimethylthiazol-2-yl)-2,5-Diphenyltetrazolium Bromide) cytotoxicity assay. The optical density (OD) of each well was obtained and recorded at 570 nm for 24 h (t1), 48 h (t2), 72 h (t3), and 5 days (t4) using a microplate reader. Results: The results of Si-Zn-doped HA showed a high specific surface area with an irregular nano-sized spherical particle structure. The atomic percentage provided the ratio of calcium to phosphate; for non-doped HA, the atomic Ca/P ratio was 1.6, but for Si-Zn-doped HA, where Zn+2 Ca and Si + replaced 4 substituted P, the atomic ratio (Ca + Zn)/(P + Si) was 1.76. The average crystal size of Si-Zn-doped HA was 46 nm, while for non-doped HA it was 61 nm. both samples were non-toxic and statistically significantly less viable than the control group After 5 days, the mean cell viability of Si-Zn-doped HA (79.17 ± 2.18) was higher than that of non-doped HA (76.26 ± 1.71) (P = 0.091). Conclusions: The MTT assay results showed that Si-Zn-doped HA is biocompatible. In addition, it showed characteristic physiochemical properties of a large surface area with interconnected porosity.

Investigate the in vitro biocompatibility, biodegradation, cytotoxicity, and differentiation potential of 3-D gelatin-nanocellulose composite scaffolds loaded with nanohydroxyapatite and simvastatin.

Bone tissue engineering has been proposed as a promising solution for healing of bone fractures. An important aspect of bone tissue engineering is the implantable scaffolds that participate in the regeneration and repair of bone tissue. In this study, the composite scaffolds of gelatin- nanocellulose loaded with nanohydroxyapatite and simvastatin (as the osteoinductive component) were fabricated using freeze- drying method. Scaffolds were characterized in terms of morphology, mechanical, biodegradability, water absorption capacity, and simvastatin release characteristics. Also, the biocompatibility and differentiation potential of the scaffolds were evaluated on human bone marrow-derived mesenchymal stem cells using the MTT assay and alizarin red staining, respectively. The simvastatin loaded scaffolds showed a sustained release profile in vitro up to 216 h. The results of BMSCs differentiation by alizarin red staining showed significant differences between the simvastatin loaded group and other groups. Moreover, the results of MTT assay verified cytocompatibility and non-toxicity of the scaffolds. Therefore, the gelatin-nano cellulose composite scaffolds loaded with hydroxyapatite and simvastatin may be considered promising for use in bone tissue engineering.

Clinical Evaluation of the Effect of Nanohydroxyapatite Lozenge on the pH of Dental Plaque.

Purpose: This study investigated the influence of nanohydroxyapatite-containing (nanoHAP) lozenge on plaque pH following sucrose intake. Patients and Methods: Sixteen adult subjects were enrolled in this double-blind crossover study composed of four interventions: (1) 10% w/v sucrose solution, (2) 10% w/v sorbitol solution, (3) nanoHAP lozenge, and (4) 10% w/v sucrose solution challenge followed by nanoHAP lozenge. Following the determination of each subject's resting plaque pH, the pH was measured at different time intervals from 3 to 30 minutes from the start of intervention, with 7 days interval between the applications of different interventions. The data were analyzed using the analysis of variance and Tukey's test (α < 0.05). Results: While sorbitol produces no change in plaque pH, nanoHAP-lozenge increased the plaque pH from a baseline of 7.0 ± 0.3 (mean ± sd) to 7.8 ± 0.2 (mean ± sd) within 30 minutes. Sucrose lowered the plaque pH from a baseline of 7.0 ± 0.4 (mean ± sd) to the lowest minimum of 5.1 ± 0.1 (mean ± sd) at the 7th minute, rising above the critical pH of enamel dissolution (5.5) at 12th minute and the baseline pH in more than 30 minutes. With lozenge intervention following sucrose challenge, plaque pH rose to 5.5 in 8 min, and to the baseline pH in 24 min. The cH area (Hydrogen ion concentration area) produced by sucrose (1.82 sq. units) was significantly (p < 0.05) greater than that produced when sucrose was challenged with lozenge (0.48 sq. units). Conclusion: Nanohydroxyapatite-containing lozenge increased plaque pH, reduced plaque pH drop in the presence of sucrose, and facilitated the rapid recovery of plaque pH after sucrose intake.

Enhancing melanoma therapy by modulating the immunosuppressive microenvironment with an MMP-2 sensitive and nHA/GNE co-encapsulated hydrogel.

The immunosuppressive tumor microenvironment, such as lactic acid and matrix metalloproteinases (MMPs) overexpression, has been well confirmed to be adverse for tumor therapy. In current study, a tumor microenvironment modulatory hydrogel was successfully developed to treat melanoma by taking advantage of the synergistic effects of nano-hydroxyapatite (nHA) with well-documented selective anti-tumor action, lactate dehydrogenase A inhibitor (R)-GNE-140 (GNE), and matrix metalloproteinase-2 (MMP-2) sensitive peptide. The hydrogel was acquired by the reaction of 4-arm-polyethylene glycol-maleic anhydride (4-arm-PEG-MAL) and MMP-2 sensitive peptide (CC-14), in which nHA and GNE were co-encapsulated physically. The in vitro degradation tests confirmed the accelerated release of nHA and GNE from the hydrogel under less-acidic (pH 6.8) and MMP-2 containing conditions compared to those neutral or without MMP-2 conditions, demonstrating the pH and MMP-2 responsive properties of as-prepared hydrogel. Findings from in vitro cell experiments revealed that the hydrogel could stop the proliferation of melanoma cells by stacking cell cycle via lactic acid metabolic dysregulation and boosting cell apoptosis via nHA direct killing effect. Moreover, after hydrogel treatment, the rate of migration and aggressiveness of melanoma cells both reduced significantly. An in vivo anti-melanoma study showed that the hydrogel could inhibit tumor growth significantly and result in more CD8+ T cells and antigen-presenting cells but less Treg cells infiltration, ultimately leading to an enhanced therapeutic efficacy. As thus, the fabricated hydrogel demonstrated great promise for treating melanoma and could be a new potent strategy for efficient melanoma therapy. STATEMENT OF SIGNIFICANCE: Nano-hydroxyapatite (nHA) has the capability of selectively killing cancer cells. The study reported a tumor microenvironment (TME) modulatory hydrogel with the goal of enhancing melanoma therapy efficacy by combining nHA administration with immunosuppressive microenvironment modulation. The hydrogel demonstrated pH and MMP-2 sensitivity. Hence, controlled release of nHA and lactate dehydrogenase A inhibitor (GNE) could be observed, and in situ MMP-2 consumption at the tumor site occurred. The hydrogel effectively inhibited the growth of melanoma cells. Furthermore, hydrogel increased the production of CD8+ T cells and antigen-presenting cells while decreasing the infiltration of Treg cells at the tumor site. This could transform the initial "cold" tumor into a "hot" tumor, ultimately resulting in an enhanced therapeutic effect.

Injectable hybrid nanofibrous spheres made of PLA and nano-hydroxyapatite for cell delivery and osteogenic induction.

Introduction: Nanofibrous spheres, with their injectable format and biomimetic three-dimensional topologies that emulate the complexity of natural extracellular environments, have become increasingly attractive for applications in biomedical and regenerative medicine. Our research contributes to this growing field by detailing the design and fabrication of a novel series of polylactic acid/nano-hydroxyapatite (PLA/nHA) hybrid nanofibrous spheres. Methods: These advanced structures were created by integrating electrospinning and electrospray techniques, which allowed for precise control over the nanofibrous spheres, especially in size. We have conducted a comprehensive investigation into the nanofibrous spheres' capacity to deliver stem cells efficiently and maintain their viability post-implantation, as well as their potential to induce osteogenic differentiation. Results and Discussion: The results show that these nanofibrous spheres are biocompatible and injectable, effectively supporting the attachment, growth, and differentiation of bone marrow-derived mesenchymal stem cells while aiding in their targeted transportation to bone defect areas to execute their regenerative functions. The findings of this study could significantly impact the future development of biocompatible materials for a range of therapeutic applications, including bone tissue engineering and regenerative therapy.

Sequential release of vancomycin and BMP-2 from chitosan/nano-hydroxyapatite thermosensitive hydrogel for the treatment of chronic osteomyelitis.

In this study, we developed scaffolds materials with microspheres to form a double sustained release system.Chitosan/nano-hydroxyapatite (CS-HA) was used as a drug carrier to construct a sustained-release system for Bone morphogenetic protein-2(BMP-2) and Vancomycin (VAN). Furthermore, VAN and BMP-2 loaded microspheres (Ms) were prepared by the emulsion ultrasonic method.The resultant composites were characterized by Scanning electron microscope (SEM), compressive strength, porosity, and biodegradation. The characterization results showed uniform porous and rough surface, enhanced thermal stability, and highest compressive strength ((1.912 ± 0.012) Kpa, the surface of the two microspheres was slightly folded and showed a regular spherical shape.The loading rate of BMP-2 was (59.611 × 10-4 ± 0.023 × 10-4)% and the encapsulation rate was (6.022 ± 0.005)%. The release rate of vancomycin and BMP-2 was 57.194% and 12.968% respectively. Osteogenic differentiation of Bone marrow mesenchymal stem cells (BMSCs) was confirmed by alkaline phosphatase quantification. The deposition of late osteogenic markers (calcium phosphates) detected by Alizarin red, which indicated extracellular matrix mineralization. The results showed that BMP-2/VAN in CS-HA hydrogel successfully achieved the sequential release of the double drugs, which could benefit bone regeneration.

Phosphoramide Hydrogels as Biodegradable Matrices for Inkjet Printing and Their Nano-Hydroxyapatite Composites.

Inkjet printing is a leading technology in the biofabrication of three-dimensional biomaterials, offering digital, noncontact deposition with micron-level precision. Among these materials, hydroxyapatite is widely recognized for its use in bone tissue engineering. However, most hydroxyapatite-laden inks are unsuitable for inkjet printing. To address this, we developed photocurable and biodegradable phosphoramide-based hydrogels containing thiol-functionalized polyethylene glycol via click chemistry. These hydrogels degrade into phosphates, the natural component of bone. The rheological properties of the inks are finely tuned through chemical design to meet the requirements of nanohydroxyapatite composite inks for piezoelectric inkjet printing. We demonstrated their printability using simple geometric patterns, showcasing a versatile and efficient solution for the precise inkjet printing of biomaterial composites.

Clinical and histological efficacy of a new implant surface in achieving early and stable osseointegration: An in vivo study.

An advantage of treated implant surfaces is their increased degree of hydrophilicity and wettability compared with untreated, machined, smooth surfaces that are hydrophobic. The present preclinical in vivo study aimed to compare the two implant surface types, namely SLActive (Straumann, Basel, Switzerland) and nanohydroxyapatite (Hiossen, Englewood Cliffs, NJ, USA), in achieving early osseointegration. The authors hypothesised that the nanohydroxyapatite surface is comparable to SLActive for early bone-implant contact. Six male mixed foxhounds underwent mandibular premolar and first molar extraction, and the sockets healed for 42 days. The mandibles were randomised to receive implants with either SLActive (control group) or nanohydroxyapatite surfaces (test group). A total of 36 implants were placed in 6 animals, and they were sacrificed at 2 weeks (2 animals), 4 weeks (2 animals) and 6 weeks (2 animals) after implant surgery. When radiographic analysis was performed, the difference in bone level between the two groups was statistically significant at 4 weeks (P = 0.024) and 6 weeks (P = 0.008), indicating that the crestal bone level was better maintained for the test group versus the control group. The bone-implant contact was also higher for the test group at 2 (P = 0.012) and 4 weeks (P = 0.011), indicating early osseointegration. In conclusion, this study underscored the potential of implants with nanohydroxyapatite surfaces to achieve early osseointegration.

Effect of adding sodium fluoride and nano-hydroxyapatite nanoparticles to the universal adhesive on bond strength and microleakage on caries-affected primary molars.

Evaluation of micro tensile bond strength (µTBS) and marginal leakage of sodium fluoride (NaF) and nano-hydroxyapatite (n-HA) modified universal adhesives (UAs) bonded using etch-and-rinse (ER) and self-etch (SE) bonding technique to the carious affected dentin (CAD). One hundred and twenty primary molars were prepared for CAD on the occlusal surface. The occlusal CAD surface was flattened and underwent a polishing procedure. The specimens were divided into six groups using a random allocation method based on the UAs applied and the mode of etching used (n = 20) Group A1: UAs (ER), Group B1: UAs (SE), Group A2: UAs (NaF) + ER, Group B2: UAs (NaF) + SE, Group A3: UA (n-HA) + ER and Group B3: UAs (n-HA) + SE. Composite restoration was placed and samples were thermocycled. Microleakage, µTBS, and failure mode assessment were performed using a dye penetration test, universal testing equipment, and stereomicroscope respectively. The µTBS and microleakage results (mean ± SD) were examined using analysis of the variance (ANOVA) and Tukey post hoc tests. Group B1 (UAs + SE) demonstrated the maximum scores of microleakage (25.14 ± 9.12 nm) and minimum recorded value of µTBS (14.16 ± 0.55 MPa). In contrast, Group A3 (UAs (n-HA) + ER) displayed a minimum value of marginal leakage (12.32 ± 6.33 nm) and maximum µTBS scores (19.22 ± 0.92 MPa). The outcomes of the intergroup comparison analysis showed that Group A2 (UAs (NaF) + ER), Group B2 (UAs (NaF) + SE), Group A3 (UA (n-HA) + ER) and Group B3 (UAs (n-HA) + SE) presented comparable outcomes of marginal seal outcomes and µTBS scores (p > 0.05). NaF and n-HA-modified UAs displayed favorable bond strength and minimum marginal leakage to the deciduous affected dentin surface.

Synthesis and characterization of injectable thermosensitive hydrogel based on Pluronic-grafted silk fibroin copolymer containing hydroxyapatite nanoparticles as potential for bone tissue engineering.

Injectable hydrogels are promising for bone tissue engineering due to their minimally invasive application and adaptability to irregular defects. This study presents the development of pluronic grafted silk fibroin (PF-127-g-SF), a temperature-sensitive graft copolymer synthesized from SF and modified PF-127 via a carbodiimide coupling reaction. The PF-127-g-SF copolymer exhibited a higher sol-gel transition temperature (34 °C at 16 % w/v) compared to PF-127 (23 °C), making it suitable for injectable applications. It also showed improved flexibility and strength, with a yielding point increase from <10 % to nearly 30 %. Unlike PF-127 gel, which degrades within 72 h in aqueous media, the PF-127-g-SF copolymer maintained a stable gel structure for over two weeks due to its robust crosslinked hydrogel network. Incorporating hydroxyapatite nanoparticles (n-HA) into the hydrogel reduced pore size and decreased swelling and degradation rates, extending structural stability to four weeks. Increasing n-HA concentration from 0 % to 20 % reduced porosity from 80 % to 66 %. Rheological studies indicated that n-HA enhanced the scaffold's strength and mechanical properties without altering gelation temperature. Cellular studies with MG-63 cells showed that n-HA concentration influenced cell viability and mineralization, highlighting the scaffold's potential in bone tissue engineering.

Integrating molecular-caged nano-hydroxyapatite into post-crosslinked PVA nanofibers for artificial periosteum.

Artificial periosteum is deemed a novel strategy for inducing endogenous bone regeneration, but ideal periosteum substitutes achieved by orchestrating a biomimetic microenvironment for bone regeneration remain a significant challenge. Here, we design and fabricate a hybridized nanofiber-based artificial periosteum with boosted osteoinduction properties. Via a "molecular cage" biomineralization strategy, nano-hydroxyapatite (nano-HAp) with a controllable size (∼22 nm) and excellent dispersion serves as unique nano-additives for water-soluble polyvinyl-alcohol (PVA)-based artificial periosteum. The PVA/HAp composite is electrospun into nanofibers to replicate the extracellular-matrix-inspired nanostructure for inducing cell adhesion, proliferation, and fate manipulation. A simple post-crosslinking treatment is subsequently applied to further booster its mechanical strength (6.6 MPa) and swelling stability. The optimized sample of C-PVA/HAp (10 wt% nano-HAp) artificial periosteum features excellent biocompatibility and remarkable in vitro mineralization. Cell experiments demonstrate that its effectively boasted cell modulation for enhanced osteogenesis without the aid of growth factors, showing a possible activation of the ERK/MAPK signaling pathway. This work provides an effective strategy for designing novel HAp nano-additives and expands the possibility of biomimetic fabrication for more advanced nanofiber-based artificial periosteum.

Polystyrene microplastics as carriers for nano-hydroxyapatite particles: Impact of surface functionalization and mechanistic insights.

The potential of microplastics (MPs) to act as carriers for contaminants or engineered nanomaterials is of rising concern. However, directly determining the vector effect of polystyrene (PS) MPs towards nano-hydroxyapatite (nHAP) particles, a typical nano phosphorus fertilizer and soil remediation material, has been rarely studied. In this study, the interaction of differentially surface functionalized PS MPs with nHAP were investigated through batch experiments under different solution chemistry conditions. The results demonstrated that nHAP had the highest attachment/adsorption affinity onto carboxyl-functionalized PS, followed by bare PS and amino-functionalized PS under near-neutral pH conditions. Adsorption of nHAP exhibited a strong pH-dependent behavior with PS MPs, increasing under acidic-neutral pH (3-7) and decreasing at higher pH values. The presence of humic acid and NaCl hindered the adsorption of nHAP onto MPs. Scanning electron microscopy observations revealed a rod-like morphology for adsorbed nHAP, which was randomly distributed on MPs surface. Surface complexation and cation-π interaction were mainly responsible for the adsorption of nHAP as revealed by multiple spectroscopic analyses. These results provide mechanistic insights into nHAP-PS interactions and expound the effect of surface functionalization of PS on binding mechanisms, and thus bring important clues for better understanding the vector effects of MPs towards nanoparticles.

Evaluation of Remineralization Efficacy of Nanoparticle-based Materials on White Spot Lesions in Children: A Comparative Clinical Study.

Background: Despite the introduction of several anticaries products, dental caries continues to be a global problem. In recent years, there has been a rise in interest in noninvasive treatment for noncavitated caries lesions by employing remineralization concepts. Each remineralizing agent has its own drawbacks. Therefore, it is desirable to seek new agents that offer the advantages of earlier counterparts with lower detrimental reactions. Aim: The purpose of this research is to evaluate the remineralization efficacy of nanoparticle-based materials on white spot lesion (WSL) in children. Materials and methods: A total of 45 children between the age-group of 4 and 8 years with WSLs were selected and randomly divided into three groups. At baseline, the teeth with WSLs were confirmed and identified using International Caries Detection and Assessment System II (ICDAS II) criteria, and the dimensions of the lesions were measured using photographic methods. Then, they were randomly placed into three groups of 15 samples each-group I nanosilver fluoride (NSF), group II nanohydroxyapatite (nano-HAP) serum, and group III MI varnish. Following that, the varnish was applied, and follow-up was done in the 2nd, 4th, 12th, and 24th week. Results: By the 4th week, all three groups had a statistically significant difference (p < 0.05). Baseline measurements for groups I, II, and III showed that their respective mean WSL dimensions were 4.9 ± 0.66, 4.27 ± 0.69, and 5.44 ± 2.95. The dimensions of each group were reduced by the 24th week to 1.22 ± 0.46, 0.93 ± 0.41, and 2.19 ± 1.40, respectively. Overall, group II (nano-HAP serum) showed a statistically significant decrease in the dimension of the lesion at the end of the 24th week, followed by groups I and III. Conclusion: The remineralization of enamel was induced by all three agents. Nano-HAP serum is more successful than MI Varnish and NSF. How to cite this article: Annadurai T, Vundela RR, Chowdhary N, et al. Evaluation of Remineralization Efficacy of Nanoparticle-based Materials on White Spot Lesions in Children: A Comparative Clinical Study. Int J Clin Pediatr Dent 2024;17(4):425-432.

The Impact of Nano-Hydroxyapatite Scaffold Enrichment on Bone Regeneration In Vivo-A Systematic Review.

OBJECTIVES: In order to ensure improved and accelerated bone regeneration, nano-hydroxyapatite scaffolds are often enriched with different bioactive components to further accelerate and improve bone healing. In this review, we critically examined whether the enrichment of nHAp/polymer scaffolds with growth factors, hormones, polypeptides, microRNAs and exosomes improved new bone formation in vivo. MATERIALS AND METHODS: Out of 2989 articles obtained from the literature search, 106 papers were read in full, and only 12 articles met the inclusion criteria for this review. RESULTS: Several bioactive components were reported to stimulate accelerated bone regeneration in a variety of bone defect models, showing better results than bone grafting with nHAp scaffolds alone. CONCLUSIONS: The results indicated that composite materials based on nHAp are excellent candidates as bone substitutes, while nHAp scaffold enrichment further accelerates bone regeneration. The standardization of animal models should be provided in order to clearly define the most significant parameters of in vivo studies. Only in this way can the adequate comparison of findings from different in vivo studies be possible, further advancing our knowledge on bone regeneration and enabling its translation to clinical settings.

Mixing ratio of nano hydroxyapatite and Epigallocatechin-3-gallate (EGCG) towards viscosity and antibacterial effect as a potential pulp capping Material: An experimental study.

Background: Finding a new natural scaffold is challenging due to crucial impact on long-term treatment outcomes in pulp capping. In this context, nano hydroxyapatite (nano-HA) is a potential candidate having similar properties to bone tissue in the body. The compound is often synthesized with Epigallocatechin-3-gallate (EGCG) which offers anti-inflammatory and antibacterial properties. Therefore, this study aims to contribute novel insights into the development of effective pulp capping materials by determining the viscosity ratio of the combination of nano-HA and EGCG applied to the cavity according to standard pulp capping material, as well as proving the antibacterial effect against Lactobacillus acidophilus. Methods: The combination of nano-HA - EGCG is divided into three treatment groups, (G1) 1:1 ratio, (G2) 1:1.5 ratio, (G3) 1:2 ratio, as well as control group G4 (Ca(OH)2 and aquadest) with a ratio of 1:1. Meanwhile, each group is tested for viscosity using a Brookfield viscometer. The well diffusion method is used to determine the antibacterial activity by measuring the diameter of the inhibition zone for each treatment, with C1 (Ca(OH)2 and aquadest) as control group at a ratio of 1:1, and three treatment groups (nano-HA - EGCG), (C2) 0.5:1 ratio, (C3) 1:1 ratio, and (C4) 2:1 ratio. Results: The results show that there is a difference in the viscosity of each group with G3 having a viscosity of 12.0183 cP, which is closest to control. Furthermore, significant differences are also reported in antibacterial activity between control and treatment groups. Conclusion: The ratio of 1:2 (G3) has a viscosity that closely matches the standard of pulp capping materials. The combinations of nano-HA and EGCG are proven to have antibacterial power against Lactobacillus acidophilus.

Nano-hydroxyapatite-assisted enzyme-induced carbonate precipitation enhances Pb-contaminated aqueous solution and loess remediation.

Intensive agricultural activities could cause lead (Pb) bioaccumulation, threatening human health. Although the enzyme-induced carbonate precipitation (EICP) technology has been applied to tackle the aforesaid problem, the urease may denature or even lose its activity when subjected to a significant Pb2+ toxicity effect. To this end, the nano-hydroxyapatite (nHAP)-assisted EICP was proposed to reduce the mobility of Pb2+. Results indicated that a below 30% immobilization efficiency at 60 mM Pb2+ was attained under EICP. nHAP adsorbed the majority of Pb2+, preventing Pb2+ attachment to urease. Further, hydroxylphosphohedyphane or hydroxylpyromorphite was formed at 60 mM Pb2+, followed by the formation of cerussite, allowing hydroxylphosphohedyphane or hydroxylpyromorphite to be wrapped by cerussite. By contrast, carbonate-bearing hydroxylpyromorphite of higher stability (Pb10(PO4)6CO3) was developed at 20 mM Pb2+ as CO3 2- substituted the hydroxyl group in hydroxylpyromorphite. Moreover, nHAP helped EICP to form nucleated minerals. As a result, the EICP-nHAP technology raised the immobilization efficiency at 60 mM Pb2+ up to 70%. The findings highlight the potential of applying the EICP-nHAP technology to Pb-containing water bodies remediation.

Bone Morphogenetic Protein 7-Loaded Gelatin Methacrylate/Oxidized Sodium Alginate/Nano-Hydroxyapatite Composite Hydrogel for Bone Tissue Engineering.

Background: Bone tissue engineering (BTE) is a promising alternative to autologous bone grafting for the clinical treatment of bone defects, and inorganic/organic composite hydrogels as BTE scaffolds are a hot spot in current research. The construction of nano-hydroxyapatite/gelatin methacrylate/oxidized sodium alginate (nHAP/GelMA/OSA), abbreviated as HGO, composite hydrogels loaded with bone morphogenetic protein 7 (BMP7) will provide a suitable 3D microenvironment to promote cell aggregation, proliferation, and differentiation, thus facilitating bone repair and regeneration. Methods: Dually-crosslinked hydrogels were fabricated by combining GelMA and OSA, while HGO hydrogels were formulated by incorporating varying amounts of nHAP. The hydrogels were physically and chemically characterized followed by the assessment of their biocompatibility. BMP7-HGO (BHGO) hydrogels were fabricated by incorporating suitable concentrations of BMP7 into HGO hydrogels. The osteogenic potential of BHGO hydrogels was then validated through in vitro experiments and using rat femoral defect models. Results: The addition of nHAP significantly improved the physical properties of the hydrogel, and the composite hydrogel with 10% nHAP demonstrated the best overall performance among all groups. The selected concentration of HGO hydrogel served as a carrier for BMP7 loading and was evaluated for its osteogenic potential both in vivo and in vitro. The BHGO hydrogel demonstrated superior in vitro osteogenic induction and in vivo potential for repairing bone tissue compared to the outcomes observed in the blank control, BMP7, and HGO groups. Conclusion: Using hydrogel containing 10% HGO appears promising for bone tissue engineering scaffolds, especially when loaded with BMP7 to boost its osteogenic potential. However, further investigation is needed to optimize the GelMA, OSA, and nHAP ratios, along with the BMP7 concentration, to maximize the osteogenic potential.

Microstructural, Fluid Dynamic, and Mechanical Characterization of Zinc Oxide and Magnesium Chloride-Modified Hydrogel Scaffolds.

Scaffolds for the filling and regeneration of osteochondral defects are a current challenge in the biomaterials field, and solutions with greater functionality are still being sought. The novel approach of this work was to obtain scaffolds with biologically active additives possessing microstructural, permeability, and mechanical properties, mimicking the complexity of natural cartilage. Four types of scaffolds with a gelatin/alginate matrix modified with hydroxyapatite were obtained, and the relationship between the modifiers and substrate properties was evaluated. They differed in the type of second modifier used, which was hydrated MgCl2 in two proportions, ZnO, and nanohydroxyapatite. The samples were obtained by freeze-drying by using two-stage freezing. Based on microstructural observations combined with X-ray microanalysis, the microstructure of the samples and the elemental content were assessed. Permeability and mechanical tests were also performed. The scaffolds exhibited a network of interconnected pores and complex microarchitecture, with lower porosity at the surface (15 ± 7 to 29 ± 6%) and higher porosity at the center (67 ± 8 to 75 ± 8%). The additives had varying effects on the pore sizes and permeabilities of the samples. ZnO yielded the most permeable scaffolds (5.92 × 10-11 m2), whereas nanohydroxyapatite yielded the scaffold with the lowest permeability (1.18 × 10-11 m2), values within the range reported for trabecular bone. The magnesium content had no statistically significant effect on the permeability. The best mechanical parameters were obtained for ZnO samples and those containing hydrated MgCl2. The scaffold's properties meet the criteria for filling osteochondral defects. The developed scaffolds follow a biomimetic approach in terms of hierarchical microarchitecture and mechanical parameters as well as chemical composition. The obtained composite materials have the potential as biomimetic scaffolds for the regeneration of osteochondral defects.

Design and in vitro evaluation of 223Ra/99mTc-loaded spherical nano-hydroxyapatite in bone tumor therapy.

Aim: Nano-hydroxyapatite (nHA) is a good nanocarrier to load 223Ra, but the low specific activity (sp.act.) of 223Ra@nHA limits its application in medicine. Methods: We proposed a method for preparing nHA using PEG as a template, which significantly increases the sp.act of 223Ra@nHA and a new method to loaded 99mTc for in vivo tracking. Results: The nHA synthesized using PEG as a template was associated with higher sp.act for 223Ra in comparison to nHA with identical particle size and without PEG. The nHA load 99mTc-MDP was associated with higher labeling rate and stability in comparison to 99mTc. Conclusion: All these findings suggest that using PEG as a template and 99mTc-MDP could be the most effective of synthetic 223Ra/99mTc@nHA.

[Box: see text].