Ramification of zinc oxide doped hydroxyapatite biocomposites for the mineralization of osteoblasts

Ultrasmall zinc oxide nanoparticle-reinforced chitosan-fucoidan scaffolds for enhanced antibacterial activity and accelerated osteogenesis

Biomaterials derived from natural polymers have raised much attention for use in bone tissue engineering applications because of their high mechanical strength and biocompatibility. However, challenges persist in developing bone materials with the requisite physicochemical and osteogenic properties. In this study, the freeze-drying method fabricated a scaffold using chitosan and fucoidan reinforced with zinc oxide nanoparticles (CSFU@ZnO). The scaffolds were characterized and evaluated for their osteogenic differentiation, proliferation, and viability of pre-osteoblast cells (MC3T3-E1). Field emission-scanning electron microscopy analysis revealed a porous morphology with interconnected pores and hydrogen bond interaction between chitosan and fucoidan, as confirmed by Fourier transform infrared spectroscopy analysis. The combination of fucoidan with chitosan improved the mechanical properties, swelling capacity, and degradability. The CSFU@ZnO scaffold effectively inhibited the growth of S. aureus and E. coli, as shown by a zone of inhibition assay. In vitro studies revealed enhanced MC3T3-E1 viability, proliferation, and adhesion, as validated by SEM analysis. The osteogenic differentiation of the CSFU@ZnO scaffold showed increased alkaline phosphatase activity, better protein adsorption, and improved bone mineralization compared to the chitosan scaffold. These findings suggest that the ZnO nanoparticle-incorporated chitosan and fucoidan scaffold could be a good and viable material for bone tissue engineering.

Piezoelectric hydrogel with self-powered biomechanical stimulation enhances bone regeneration

Large bone defect healing remains a challenge in current clinical treatment, which suggests the need for functional bone repair materials. Piezoelectric materials can generate electrical stimulation under mechanical stress to improve the tissue healing environment, which are emerging candidates for tissue engineering. We created a self-powered piezoelectric hydrogel by simply blending the zinc oxide (ZnO) nanoparticles and regenerating silk fibroin (RSF). Our piezoelectric hydrogel showed controllable and suitable mechanical and piezoelectric properties which could generate electrical stimulation to promote bone tissue healing. Incorporating ZnO into RSF hydrogels not only enhanced their mechanical properties by 1.7 times and increased piezoelectric output by 2.8 times, but also mitigated the degradation rate. In vitro experiments showed that piezoelectric hydrogels significantly promoted osteogenesis differentiation of bone marrow mesenchymal stem cells (BMSCs) and enhanced vascular network reconstitution. In vivo experiments verified the osteogenic and angiogenic potential of ZnO/RSF piezoelectric hydrogels. ZnO/RSF piezoelectric hydrogel, a simple but universal strategy of RSF-based material to generate electric currents by body movement, provides novel insights into the applications of piezoelectric hydrogel. STATEMENT OF SIGNIFICANCE: ZnO/RSF hydrogels with stable piezoelectric properties were prepared by doping ZnO, which can generate stable and continuous electrical signals under pressure. After implantation into the bone defect site, it can promote the osteogenic differentiation of bone marrow mesenchymal stem cells and improve the vasculogenic ability of human umbilical vein endothelial cells, thus promoting the healing of bone tissue.

Development of hybrid bionanocomposites of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) with zinc oxide and silicon-doped hydroxyapatite nanocrystals and machine learning for predicting dynamic mechanical properties

The development of hybrid materials that integrate bioactive and antimicrobial properties within a biodegradable and biocompatible polymer matrix is a key focus in current biomedical research and applications. A significant research gap exists in the field of PHBV nanocomposites, particularly concerning those that simultaneously incorporate both ZnO and HAP particles. This study focuses on the fabrication and characterization of innovative hybrid bionanocomposites composed of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) combined with zinc oxide (ZnO) and silicon-doped hydroxyapatite (SiHAP) nanocrystals. The hybrid nanocomposite with 5 wt% ZnO and 0.1 wt% SiHAP exhibited the highest storage modulus, suitable for load-bearing applications. DMA analysis at 20 °C showed significant increases in storage (50.8 %) and loss (92 %) moduli for this composition. This particular group demonstrated cellular viability of approximately 100 %. Our results suggest that these newly developed novel composites demonstrate exceptional biocompatibility, bioactivity, and antimicrobial properties. As a result, they show significant potential as tissue engineering tools for addressing bone tissue disorders. Various Machine learning (ML) algorithms were applied to model the dynamic mechanical properties of nanocomposites based on experimental data. The study shows that these models provide accurate insights into the dynamic mechanical behavior of nanocomposites, offering a reliable method for optimizing their properties.

Zinc-doped hydroxyapatite loaded chitosan gelatin nanocomposite scaffolds as a promising platform for bone regeneration

The advancement in the arena of bone tissue engineering persuades us to develop novel nanocomposite scaffolds in order to improve antibacterial, osteogenic, and angiogenic properties that show resemblance to natural bone extracellular matrix. Here, we focused on the development of novel zinc-doped hydroxyapatite (ZnHAP) nanoparticles (1, 2 and 3 wt%; size: 50-60 nm) incorporated chitosan-gelatin (CG) nanocomposite scaffold, with an interconnected porous structure. The addition of ZnHAP nanoparticles decreases the pore size (∼30 µm) of the CG scaffolds. It was observed that with the increase in the concentration of ZnHAP nanoparticles (3 wt%) in CG scaffolds, the swelling ratio (1760% ± 2.0%), porosity (71% ± 0.98%) and degradation rate (35%) decreased, whereas mechanical property (1 MPa) increased, which was better as compared to control (CG) samples. Similarly, the high deposition of apatite crystals especially CG-ZnHAP3nanocomposite scaffold revealed the excellent osteoconductive potential among all other scaffolds. MC3T3-E1 osteoblastic cells seeded with CG-ZnHAP nanocomposite scaffolds depicted better cell adhesion, proliferation and differentiation to osteogenic lineages. Finally, the chorioallantoic membrane (CAM) assay revealed better angiogenesis of ZnHAP nanoparticles (3 wt%) loaded CG scaffolds supporting vascularization after 7th day incubation in the CAM area. Overall, the results showed that the CG-ZnHAP3nanocomposite scaffold could be a potential candidate for bone defect repair.

Fabrication and characterization of reinforced glass ionomer cement by zinc oxide and hydroxyapatite nanoparticles

This study shows the enhancement of glass ionomer cement (GIC) by incorporating hydroxyapatite (HA) and zinc oxide (ZnO) nanoparticles to improve its mechanical strength, biological activity, and antibacterial properties. GC is widely used in dental and orthopedic applications due to its bioactivity and biocompatibility, but it suffers from weak antibacterial properties and limited load-bearing capacity. HA, a calcium phosphate compound similar to natural bone, and ZnO, known for its antibacterial and bone-regenerative properties, were integrated into GIC to address these limitations. The modified GC exhibited improved compressive strength and bioactivity, particularly with the addition of 4 wt% ZnO nanoparticles, which showed the highest increase in mechanical performance while maintaining cytocompatibility. However, the fluoride release was reduced, indicating an exchange between enhanced mechanical properties and fluoride ion release. Antibacterial efficacy was assessed using well diffusion, MIC, and MBC tests, confirming that the modified GC has significant potential in dental and orthopedic applications. Future research should focus on the long-term effects of Zn2⁺ ion release to fully understand its impact on the antibacterial performance of the cement.

Characterization of hFOB 1.19 Cell Line for Studying Zn-Based Degradable Metallic Biomaterials

In vitro testing is the first important step in the development of new biomaterials. The human fetal osteoblast cell line hFOB 1.19 is a very promising cell model; however, there are vast discrepancies in cultivation protocols, especially in the cultivation temperature and the presence of the selection reagent, geneticin (G418). We intended to use hFOB 1.19 for the testing of Zn-based degradable metallic materials. However, the sensitivity of hFOB 1.19 to zinc ions has not yet been studied. Therefore, we compared the toxicity of zinc towards hFOB 1.19 under different conditions and compared it with that of the L929 mouse fibroblast cell line. We also tested the cytotoxicity of three types of Zn-based biomaterials in two types of media. The presence of G418 used as a selection reagent decreased the sensitivity of hFOB 1.19 to Zn2+. hFOB 1.19 cell line was more sensitive to Zn2+ at elevated (restrictive) temperatures. hFOB 1.19 cell line was less sensitive to Zn2+ than L929 cell line (both as ZnCl2 and extracts of alloys). Therefore, the appropriate cultivation conditions of hFOB 1.19 during biomaterial testing should be chosen with caution.

Calcination and ion substitution improve physicochemical and biological properties of nanohydroxyapatite for bone tissue engineering applications

Nanohydroxyapatite (nanoHAP) is widely used in bone regeneration, but there is a need to enhance its properties to provide stimuli for cell commitment and osteoconduction. This study examines the effect of calcination at 1200 °C on the physicochemical and biological properties of nanoHAP doped with magnesium (Mg2+), strontium (Sr2+), and zinc (Zn2+). A synergistic effect of dual modification on nanoHAP biological properties was investigated. The materials were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), BET analysis, Fourier-transform spectroscopy, and thermal analysis methods. Furthermore, ion release tests and in vitro biological characterization, including cytocompatibility, reactive oxygen species production, osteoconductive potential and cell proliferation, were performed. The XRD results indicate that the ion substitution of nanoHAP has no effect on the apatite structure, and after calcination, β-tricalcium phosphate (β-TCP) is formed as an additional phase. SEM analysis showed that calcination induces the agglomeration of particles and changes in surface morphology. A decrease in the specific surface area and in the ion release rate was observed. Combining calcination and nanoHAP ion modification is beneficial for cell proliferation and osteoblast response and provide additional stimuli for cell commitment in bone regeneration.

Electrospinning Inorganic Nanomaterials to Fabricate Bionanocomposites for Soft and Hard Tissue Repair

Tissue engineering (TE) has attracted the widespread attention of the research community as a method of producing patient-specific tissue constructs for the repair and replacement of injured tissues. To date, different types of scaffold materials have been developed for various tissues and organs. The choice of scaffold material should take into consideration whether the mechanical properties, biodegradability, biocompatibility, and bioresorbability meet the physiological properties of the tissues. Owing to their broad range of physico-chemical properties, inorganic materials can induce a series of biological responses as scaffold fillers, which render them a good alternative to scaffold materials for tissue engineering (TE). While it is of worth to further explore mechanistic insight into the use of inorganic nanomaterials for tissue repair, in this review, we mainly focused on the utilization forms and strategies for fabricating electrospun membranes containing inorganic components based on electrospinning technology. A particular emphasis has been placed on the biological advantages of incorporating inorganic materials along with organic materials as scaffold constituents for tissue repair. As well as widely exploited natural and synthetic polymers, inorganic nanomaterials offer an enticing platform to further modulate the properties of composite scaffolds, which may help further broaden the application prospect of scaffolds for TE.

One-Pot Hydrothermal Preparation of Hydroxyapatite/Zinc Oxide Nanorod Nanocomposites and Their Cytotoxicity Evaluation against MG-63 Osteoblast-like Cells

In the present study, HAp-ZnO nanorod nanocomposites were successfully prepared using a customized hydrothermal reactor and studied for their compatibility against MG-63 osteoblast-like cells. The crystallinity, morphology, presence of chemical elements, and surface area properties were studied by XRD (X-ray diffraction), FE-SEM (field emission scanning electron microscopy), TEM (transmission electron microscopy), EDS (energy dispersive spectrum) and N₂ adsorption/desorption isotherm techniques, respectively. Further, the mechanical strength and thermal analysis were carried out using the nanoindentation method and thermogravimetric/differential scanning calorimeter (TG/DSC) methods, respectively. Moreover, in vitro biocompatibility studies for the prepared samples were carried out against human osteosarcoma cell lines (MG-63). The crystalline nature of the samples without any impurity phases was notified from XRD results. The formation of composites with the morphology of nanorods and the presence of desired elements in the intended ratio were verified using FE-SEM and EDS spectra, respectively. The TG/DSC results revealed the improved thermal stability of the HAp matrix, promoted by the reinforcement of the ZnO nanorods. The nanoindentation study ensured a significant enhancement in the mechanical stability of the prepared composite material. Finally, it demonstrated that the HAp matrix's mechanical strength and thermal stability were improved by the reinforcement of ZnO, and the cytotoxicity evaluation affirmed the biocompatible nature of the biomimetic hydroxyapatite in the composite.

Electrospun Membrane Surface Modification by Sonocoating with HA and ZnO:Ag Nanoparticles—Characterization and Evaluation of Osteoblasts and Bacterial Cell Behavior In Vitro

Guided tissue regeneration and guided bone regeneration membranes are some of the most common products used for bone regeneration in periodontal dentistry. The main disadvantage of commercially available membranes is their lack of bone cell stimulation and easy bacterial colonization. The aim of this work was to design and fabricate a new membrane construct composed of electrospun poly (D,L-lactic acid)/poly (lactic-co-glycolic acid) fibers sonocoated with layers of nanoparticles with specific properties, i.e., hydroxyapatite and bimetallic nanocomposite of zinc oxide–silver. Thus, within this study, four different variants of biomaterials were evaluated, namely: poly (D,L-lactic acid)/poly (lactic-co-glycolic acid) biomaterial, poly(D,L-lactic acid)/poly (lactic-co-glycolic acid)/nano hydroxyapatite biomaterial, poly (D,L-lactic acid)/poly (lactic-co-glycolic acid)/nano zinc oxide–silver biomaterial, and poly (D,L-lactic acid)/poly (lactic-co-glycolic acid)/nano hydroxyapatite/nano zinc oxide–silver biomaterial. First, it was demonstrated that the wettability of biomaterials—a prerequisite property important for ensuring desired biological response—was highly increased after the sonocoating process. Moreover, it was indicated that biomaterials composed of poly (D,L-lactic acid)/poly (lactic-co-glycolic acid) with or without a nano hydroxyapatite layer allowed proper osteoblast growth and proliferation, but did not have antibacterial properties. Addition of a nano zinc oxide–silver layer to the biomaterial inhibited growth of bacterial cells around the membrane, but at the same time induced very high cytotoxicity towards osteoblasts. Most importantly, enrichment of this biomaterial with a supplementary underlayer of nano hydroxyapatite allowed for the preservation of antibacterial properties and also a decrease in the cytotoxicity towards bone cells, associated with the presence of a nano zinc oxide–silver layer. Thus, the final structure of the composite poly (D,L-lactic acid)/poly (lactic-co-glycolic acid)/nano hydroxyapatite/nano zinc oxide–silver seems to be a promising construct for tissue engineering products, especially guided tissue regeneration/guided bone regeneration membranes. Nevertheless, additional research is needed in order to improve the developed construct, which will simultaneously protect the biomaterial from bacterial colonization and enhance the bone regeneration properties.

Development of zinc oxide/hydroxyapatite/poly(D,L-lactic acid) fibrous scaffold for tissue engineering applications

Scaffolds based on polymeric fibers represent an engaging biomedical device due to their particular morphology and similarity with extracellular matrices. The biggest challenge to use fibrous materials in the biomedical field is related to their favorable platform for the adhesion of pathogenic microorganisms. Therefore, their optimum performance not only depends on their bioactive potential but also on their antimicrobial properties. The aim of this work was the design of antimicrobial (zinc oxide, ZnO) and bioactive (hydroxyapatite, Hap) fibrous materials using poly(D, L-lactic acid) (PDLLA) as the polymer fiber substrate. Fiber based composite scaffolds were developed using the Forcespinning® technique. For analysis purposes, the morphological, thermal, antimicrobial and biological properties of the fibrous hybrid system obtained at a concentration of 5 wt% of ZnO and 5 wt% of Hap were studied. The incorporation of the aforementioned nanoparticles (NPs) mixture in PDLLA led to an increase in viscosity and a pseudo-plastic tendency of the precursor solution, which caused an increase in fiber diameters and their dispersion of values. Small cavities and certain roughness were the main surface morphology observed on the fibers before and after NPs incorporation. The fiber thermal stability decreased due to the presence of the NPs. The antimicrobial properties of the hybrid fibrous scaffold presented a growth inhibition (GI) of 70 and 85% for E. coli and S. aureus strains, respectively. Concerning the osteoblast-cell compatibility, PDLLA and hybrid PDLLA scaffold showed low toxicity (cell viabilities above 80%), allowing cell growth inside its three-dimension structure and favorable cell morphology extended along the fibers. This behavior suggests a promising potential of this hybrid PDLLA scaffold for bone application.

Effect of ZnO-doped magnesium phosphate cements on osteogenic differentiation of mBMSCs in vitro

The insufficient osteogenesis of magnesium phosphate cements (MPCs) limits its further application. It is significant to develop a bioactive MPC with osteogenic properties. In this work, MPCs were reinforced by zinc oxide nanoparticles (ZnO-NPs). The composition, microstructure, setting time, compressive strength and degradation of ZnO-NPs/MPCs (ZNMPCs) were evaluated. The results showed that the setting times of MPCs were prolonged from 8.2 to 25.3 min (5.0ZNMPC). The exothermic temperatures were reduced from 45.8 ± 0.4℃ (MPCs) to 39.3 ± 0.5℃ (1.0ZNMPC). The compressive strength of ZNMPC composite cement with 1 wt. % ZnO-NPs (1.0ZNMPC) was the highest (42.9 MPa) among all the composite cements. Furthermore, the ZNMPCs were cultured with mouse bone marrow mesenchymal stem cells (mBMSCs). The results yielded that the ZNMPCs exhibited good cytocompatibility with enhanced differentiation, proliferation, and mineralization on mBMSCs, and it also pronouncedly elevated the expressions of genes and proteins involving osteogenesis. These findings suggested that ZNMPCs could drive the differentiation toward osteogenesis and mineralization of mBMSCs, providing a simple way to the MPC with enhanced osteogenesis for further orthopedic applications.

The regulating effect of trace elements Si, Zn and Sr on mineralization of gelatin-hydroxyapatite electrospun fiber

Biomineralization approaches have been increasingly adopted to synthesizing advanced materials with superior properties. Nevertheless, the potential influence of inorganic trace elements on the mineralization process of collagen has been rarely reported, despite of the significant progress achieved on exploiting the critical roles of organic polymers in regulating the collagen mineralization. To this aim, the potential roles of Si, Zn and Sr in regulating the mineralization of gelatin-hydroxyapatite (HA) composite fibers have been examined in this study. The results indicated that the incorporation of trace elements not only promoted the biomineralization of gelatin, but also led to drastic change in the mineralization behavior. In particular, the gelatin-SiHA sample showed uniform mineralization predominantly inside the fibers, with nucleation and growth directions along the c-axis of the gelatin fibers. On the contrary, the gelatin-HA sample showed nucleation outside the fibers and spherical mineral crystals on top of fibers, typical structure for heterogeneous nucleation. As the mineralization process proceeded, the gelatin-ZnHA and gelatin-SrHA samples evolved into having similar structure as the gelatin-SiHA sample, despite of showing totally different mineralization behaviors at early time. Overall, the incorporation of trace elements seemed to lower the nucleation barriers, led to a more homogeneous mineralization mode within the fiber region and formation of mineralized structures closer to those in natural bone. Moreover, mineralized samples with trace elements demonstrated improved adhesion and cytoskeleton organization of osteoblastic cells. Such finding would provide important insight for understanding the mineralization process and the optimal design of advanced biological materials.

Bioinspired Reactive Interfaces Based on Layered Double Hydroxides-Zn Rich Hydroxyapatite with Antibacterial Activity

This work is focused on the preparation and multi-technique characterization of potentially biocompatible reactive interfaces obtained by combining layered double hydroxides (LDHs) and hydroxyapatite (HA). Antimicrobial and osteoinductive metallic ions as Zn²⁺ and Ga³⁺ were chosen as intralayer constituents of LDH to obtain ZnAl and ZnAlGa systems. These LDHs, exchanged with dihydrogenphosphate anions, promoted the precipitation of HA on the LDH surface yielding HA@LDH composites. X-ray diffraction quantitative analysis, through the Rietveld refinement method, coupled with elemental analysis and micro-Raman spectroscopy showed the formation of a mixed Ca-Zn HA phase. Scanning electron microscopy revealed that HA, in the presence of LDH, grew preferentially along its a-axis, thus crystallizing mainly in the form of flake crystals. LDH and HA@LDH composites showed antibacterial activity against Staphylococcus aureus and Pseudomonas aeruginosa at not cytotoxic concentrations for human osteoblasts (hFob 1.19), especially when Ga cations were present in the LDH structure. The effect of the presence of HA in the composites on the bone-bonding ability and on human osteoblast proliferation was also investigated. The HA seemed to reduce the toxicity of the LDH toward human osteoblast while did not affect the bone-bonding ability. This multidisciplinary study provides the bio-chemical, structural characterization of new LDH and HA@LDH composites, evaluating also their bioactivity to be potentially applicable to titanium-based prostheses.

Photocatalytic Behaviour of Zinc Oxide Nanostructures on Surface Activation of Polymeric Fibres

Zinc oxide (ZnO) in various nano forms (nanoparticles, nanorods, nanosheets, nanowires and nanoflowers) has received remarkable attention worldwide for its functional diversity in different fields i.e., paints, cosmetics, coatings, rubber and composites. The purpose of this article is to investigate the role of photocatalytic activity (role of photogenerated radical scavengers) of nano ZnO (nZnO) for the surface activation of polymeric natural fibres especially cotton and their combined effect in photocatalytic applications. Photocatalytic behaviour is a crucial property that enables nZnO as a potential and competitive candidate for commercial applications. The confirmed features of nZnO were characterised by different analytical tools, i.e., scanning electron microscopy (SEM), field emission SEM (FESEM) and elemental detection spectroscopy (EDX). These techniques confirm the size, morphology, structure, crystallinity, shape and dimensions of nZnO. The morphology and size play a crucial role in surface activation of polymeric fibres. In addition, synthesis methods, variables and some of the critical aspects of nZnO that significantly affect the photocatalytic activity are also discussed in detail. This paper delineates a vivid picture to new comers about the significance of nZnO in photocatalytic applications.

Ion release from hydroxyapatite and substituted hydroxyapatites in different immersion liquids: in vitro experiments and theoretical modelling study

Multi-substituted hydroxyapatites (ms-HAPs) are currently gaining more consideration owing to their multifunctional properties and biomimetic structure, owning thus an enhanced biological potential in orthopaedic and dental applications. In this study, nano-hydroxyapatite (HAP) substituted with multiple cations (Sr2+, Mg2+ and Zn2+) for Ca2+ and anion ( Si O 4 4 - ) for P O 4 3 - and OH-, specifically HAPc-5%Sr and HAPc-10%Sr (where HAPc is HAP-1.5%Mg-0.2%Zn-0.2%Si), both lyophilized non-calcined and lyophilized calcined, were evaluated for their in vitro ions release. These nanomaterials were characterized by scanning electron microscopy, field emission-scanning electron microscopy and energy-dispersive X-ray, as well as by atomic force microscope images and by surface specific areas and porosity. Further, the release of cations and of phosphate anions were assessed from nano-HAP and ms-HAPs, both in water and in simulated body fluid, in static and simulated dynamic conditions, using inductively coupled plasma optical emission spectrometry. The release profiles were analysed and the influence of experimental conditions was determined for each of the six nanomaterials and for various periods of time. The pH of the samples soaked in the immersion liquids was also measured. The ion release mechanism was theoretically investigated using the Korsmeyer-Peppas model. The results indicated a mechanism principally based on diffusion and dissolution, with possible contribution of ion exchange. The surface of ms-HAP nanoparticles is more susceptible to dissolution into immersion liquids owing to the lattice strain provoked by simultaneous multi-substitution in HAP structure. According to the findings, it is rational to suggest that both materials HAPc-5%Sr and HAPc-10%Sr are bioactive and can be potential candidates in bone tissue regeneration.

Enhancing ZnO-NP Antibacterial and Osteogenesis Properties in Orthopedic Applications: A Review

Prosthesis-associated infections and aseptic loosening are major causes of implant failure. There is an urgent need to improve the antibacterial ability and osseointegration of orthopedic implants. Zinc oxide nanoparticles (ZnO-NPs) are a common type of zinc-containing metal oxide nanoparticles that have been widely studied in many fields, such as food packaging, pollution treatment, and biomedicine. The ZnO-NPs have low toxicity and good biological functions, as well as antibacterial, anticancer, and osteogenic capabilities. Furthermore, ZnO-NPs can be easily obtained through various methods. Among them, green preparation methods can improve the bioactivity of ZnO-NPs and strengthen their potential application in the biological field. This review discusses the antibacterial abilities of ZnO-NPs, including mechanisms and influencing factors. The toxicity and shortcomings of anticancer applications are summarized. Furthermore, osteogenic mechanisms and synergy with other materials are introduced. Green preparation methods are also briefly reviewed.

Delivery of Salvianolic Acid B for Efficient Osteogenesis and Angiogenesis from Silk Fibroin Combined with Graphene Oxide

The efficiency of drugs often hinges on drug carriers. To effectively transport therapeutic plant molecules, drug delivery carriers should be able to carry large doses of therapeutic drugs, enable their sustained release, and maintain their biological activity. Here, graphene oxide (GO) is demonstrated to be a valid carrier for delivering therapeutic plant molecules. Salvianolic acid B (SB), which contains a large number of hydroxyl groups, bound to the carboxyl groups of GO by self-assembly. Silk fibroin (SF) substrates were combined with functionalized GO through the freeze-drying method. SF/GO scaffolds could be loaded with large doses of SB, maintain the biological activity of SB while continuously releasing SB, and significantly promote the osteogenic differentiation of rat bone marrow mesenchymal stem cells (rBMSCs). SF/GO/SB also dramatically enhanced endothelial cell (EA-hy9.26) migration and tubulogenesis in vitro. Eight weeks after implantation of SF/GO/SB scaffolds in a rat cranial defect model, the defect area showed more new bone and angiogenesis than that following SF and SF/GO scaffold implantation. Therefore, GO is an effective sustained-release carrier for therapeutic plant molecules, such as SB, which can repair bone defects by promoting osteogenic differentiation and angiogenesis.

Transition metal-doped cryogels as bioactive materials for wound healing applications

Transition metals (TM) are essential microelements with various biological functions demanded in tissue regeneration applications. Little is known about therapeutic potential of TM within soft hydrogel biomaterials. The soluble divalent TM, such as Zn, Cu, Mn and Co, were stably incorporated into gelatin network during cryogelation. TM content in the resultant cryogels varied from 0.1 × 10³ to 11.8 × 10³ ppm, depending on the TM type and concentration in the reaction solution. Zn component was uniformly complexed with the gelatin scaffold according to elemental imaging, increasing the swelling of polymer walls and the G'/G″ values and also decreasing the size of cryogel macro-pores. Zn-doped cryogels supported migration of human skin fibroblasts (HSF); only upper Zn content of 11.8 × 10³ ppm in the scaffold caused c.a. 50% inhibition of cell growth. Zn ions solubilized in culture medium were more active towards HSF (IC₅₀ ≈ 0.3 mM). Treatment of splinted full-skin excisional wounds in rats with the Zn-doped and non-doped cryogels showed that Zn considerably promoted passing inflammatory/proliferation phases of healing process, inducing more intense dermis formation and structuration. The results show the feasibility of development of cryogel based formulations with different TM and support high phase-specific ability of the Zn-gelatin cryogels to repair acute wounds.