Preparation and bioactivity evaluation of hydroxyapatite-titania/chitosan-gelatin polymeric biocomposites

Development of novel hybrid nanomaterials with potential application in bone/dental tissue engineering: design, fabrication and characterization enriched-SAPO-34/CS/PANI scaffold

Fe-Ca-SAPO-34/CS/PANI, a novel hybrid bio-composite scaffold with potential application in dental tissue engineering, was prepared by freeze drying technique. The scaffold was characterized using FT-IR and SEM methods. The effects of PANI on the physicochemical properties of the Fe-Ca-SAPO-34/CS scaffold were investigated, including changes in swelling ratio, mechanical behavior, density, porosity, biodegradation, and biomineralization. Compared to the Fe-Ca-SAPO-34/CS scaffold, adding PANI decreased the pore size, porosity, swelling ratio, and biodegradation, while increasing the mechanical strength and biomineralization. Cell viability, cytotoxicity, and adhesion of human dental pulp stem cells (hDPSCs) on the scaffolds were investigated by MTT assay and SEM. The Fe-Ca-SAPO-34/CS/PANI scaffold promoted hDPSC proliferation and osteogenic differentiation compared to the Fe-Ca-SAPO-34/CS scaffold. Alizarin red staining, alkaline phosphatase activity, and qRT-PCR results revealed that Fe-Ca-SAPO-34/CS/PANI triggered osteoblast/odontoblast differentiation in hDPSCs through the up-regulation of osteogenic marker genes BGLAP, RUNX2, and SPARC. The significance of this study lies in developing a novel scaffold that synergistically combines the beneficial properties of Fe-Ca-SAPO-34, chitosan, and PANI to create an optimized microenvironment for dental tissue regeneration. These findings highlight the potential of the Fe-Ca-SAPO-34/CS/PANI scaffold as a promising biomaterial for dental tissue engineering applications, paving the way for future research and clinical translation in regenerative dentistry.

Self-assembled chitosan/gelatin nanofibrous aggregates incorporated thermosensitive nanocomposite bioink for bone tissue engineering

Chitosan-based thermosensitive bioink can be a potential option as bioinks for bone tissue engineering because of their excellent biocompatibility and crosslinker-free gelation at physiological temperature. However, their low mechanical strength, poor printability, and low post-printing cell viability are some of their limitations. In this work, self-assembled nanofibrous aggregates of chitosan and gelatin were prepared and incorporated in chitosan-based bioinks to enhance printability, mechanical properties, post-printing cell viability, and proliferation. Subsequently, the optimal concentration of nanohydroxyapatite was determined, and the potential of the nanocomposite bioink was evaluated. Physiochemical, mechanical, and in vitro characterizations were carried out for the developed nanocomposite bioink. The bioink had optimum printability at 10 % nanohydroxyapatite and cell viability >88 %. The composite bioink had a low water uptake capacity (2.5 %) and degraded within 3 weeks in the presence of lysozyme. Mechanical characterization revealed an elastic modulus of about 15.5 kPa. Rheological analysis indicated a higher storage modulus of the bioink samples at 37 °C. ALP activity of 36.8 units/ml after 14 days of scaffold culture in osteogenic media indicated high cellular activity. These results suggested that the incorporation of osteogenic nanohydroxyapatite and nanofibrous aggregates improved the overall osteogenic and physiochemical potential of the thermosensitive bioink.

Development of HAp/GO/Ag coating on 316 LVM implant for medical applications

In this study, antibacterial activity, biocompatibility, and corrosion resistance of 316 LVM implants were improved using the development of HAp/GO/Ag nanocomposite coatings by the dip-coating method. The XRD and FTIR results confirmed the synthesis of HAp/GO/Ag nanocomposites. HAp/Ag nanoparticles (68 nm) bound to epoxy, hydroxyl, and carboxyl functional groups on GO sheets (size of GO sheets varies from 255 to 1480 nm) by electrostatic interaction. FESEM images showed that HAp/GO/Ag coatings had higher density and fewer micro-cracks than pure HAp coatings. In addition, HAp/GO/Ag coatings showed optimized nano-hardness (4.5 GPa) and elasticity modulus (123 GPa). The results of potentiodynamic polarization demonstrated that HAp/GO/Ag coating has the lowest corrosion current density (0.31 μA/cm²), maximum protection efficiency (90.0%), and lowest release of Fe, Cr, and Ni ions (31, 24, and 15 ppb). In addition, EIS results showed that HAp/GO/Ag coatings could prevent electrolyte access to the substrate and provide high bio-corrosion resistance. A bone-like layer is formed on nanocomposite coatings after 28 days in SBF, proving that Ag and GO's addition does not interfere with the mineralization process. After 28 days of immersion in SBF, the lowest release of Fe, Cr, and Ni ions is related to nanocomposite coatings. Also, the release of Ag⁺ ions from the coatings is between 0.13 and 1.41, providing antibacterial activity without cytotoxicity. HAp/GO, HAp/Ag, and HAp/GO/Ag nanocomposites kill 47%, 92%, and 98% of E. coli bacteria, respectively. HAp/GO, HAp/Ag, and HAp/GO/Ag nanocomposites kill 47%, 92%, and 98% of E. coli bacteria, respectively. The cell culture results showed that human MG-63 osteoblast-like cells in contact with HAp/GO/Ag coating had the highest biocompatibility (98% of cells survived). Therefore, the development of HAp/GO/Ag nanocomposite coating on 316 LVM implant shows improved properties of nano hardness, corrosion resistance, antibacterial activity, and biocompatibility properties, which is a new turning point for nanocomposite coatings for medical applications.

Bioactive glass doped with noble metal nanoparticles for bone regeneration: in vitro kinetics and proliferative impact on human bone cell line

This work investigates the bioactivity of novel silver-doped (BG-Ag) and gold-doped (BG-Au) quaternary 46S6 bioactive glasses synthesized via a semi-solid-state technique. A pseudo-second-order kinetic model successfully predicted the in vitro uptake kinetic profiles of the initial ion-exchange release of Ca in simulated body fluid, the subsequent Si release, and finally, the adsorption of Ca and P onto the bioactive glasses. Doping with silver nanoparticles enhanced the rate of P uptake by up to approximately 90%; whereas doping with gold nanoparticles improved Ca and P uptake rates by up to about 7 and 2 times, respectively; as well as Ca uptake capacity by up to about 19%. The results revealed that the combined effect of Ca and Si release, and possibly the release of silver and gold ions into solution, influenced apatite formation due to their effect on Ca and P uptake rate and capacity. In general, gold-doped bioactive glasses are favoured for enhancing Ca and P uptake rates in addition to Ca uptake capacity. However, silver-doped bioactive glasses being less expensive can be utilized for applications targeting rapid healing. In vitro studies showed that BG, BG-Ag and BG-Au had no cytotoxic effects on osteosarcoma MG-63 cells, while they exhibited a remarkable cell proliferation even at low concentration. The prepared bioactive glass doped with noble metal nanoparticles could be potentially used in bone regeneration applications.

In vitro characterization of novel nanostructured collagen-hydroxyapatite composite scaffolds doped with magnesium with improved biodegradation rate for hard tissue regeneration

New materials are required for bone healing in regenerative medicine able to temporarily substitute damaged bone and to be subsequently resorbed and replaced by endogenous tissues. Taking inspiration from basic composition of the mammalian bones, composed of collagen, apatite and a number of substitution ions, among them magnesium (Mg²⁺), in this work, novel composite scaffolds composed of collagen(10%)-hydroxyapatite (HAp)(90%) and collagen(10%)-HAp(80%)-Mg(10%) were developed. The lyophilization was used for composites preparation. An insight into the nanostructural nature of the developed scaffolds was performed by Scanning Electron Microscopy coupled with Energy Dispersive X-Ray and Transmission Electron Microscopy coupled with Energy Dispersive X-Ray. The HAp nanocrystallite clusters and Mg nanoparticles were homogeneously distributed within the scaffolds and adherent to the collagen fibrils. The samples were tested for degradation in Simulated Body Fluid (SBF) solution by soaking for up to 28 days. The release of Mg from collagen(10%)-HAp(80%)-Mg(10%) composite during the period of up to 21 days was attested, this composite being characterized by a decreased degradation rate with respect to the composite without Mg. The developed composite materials are promising for applications as bone substitute materials favouring bone healing and regeneration.

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Lyophilization process was used to obtain new composite scaffolds.

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Collagen(10%)-HAp(90%) and collagen(10%)-HAp(80%)-Mg(10%) scaffolds were developed.

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HAp nanocrystallites and Mg nanoparticles are embedded into collagen fibrils.

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Degradation in SBF attested the Mg release from composite during up to 21 days.

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Composite collagen(10%)-HAp(80%)-Mg(10%) scaffold can be applied as bone substitute.

Enhanced biomineralization and protein adsorption capacity of 3D chitosan/hydroxyapatite biomimetic scaffolds applied for bone-tissue engineering

This work presents the enhanced biomineralization and protein adsorption capacity of 3D chitosan/hydroxyapatite (CS/HAp) biomimetic scaffolds synthesized from natural sources applied for bone-tissue engineering (BTE).

Niobium pentoxide and hydroxyapatite particle loaded electrospun polycaprolactone/gelatin membranes for bone tissue engineering

Effective methods of accelerating the bone regeneration healing process are in demand for a number of bone-related diseases and trauma. This work developed scaffolds with improved properties for bone tissue engineering by electrospinning composite polycaprolactone-gelatin-hydroxyapatite-niobium pentoxide (PGHANb) membranes. Composite membranes, with average fiber diameters ranging from 123 to 156 nm, were produced by adding hydroxyapatite (HA) and varying concentrations of niobium pentoxide (Nb₂O₅) particles (0, 3, 7, and 10 wt%) to a polycaprolactone (PCL) and gelatin (GL) matrix prior to electrospinning. The morphology, mechanical, chemical and biological properties of resultant membranes were evaluated. Bioactivity was assessed using simulated body fluid (SBF) and it confirmed that the presence of particles induced the formation of hydroxyapatite crystals on the surface of the membranes. Samples were hydrophilic and cell metabolism results showed that the niobium-containing membranes were non-toxic while improving cell proliferation and differentiation compared to controls. This study demonstrated that electrospun membranes containing HA and Nb₂O₅ particles have potential to promote cell adhesion and proliferation while exhibiting bioactive properties. PGHANb membranes are promising candidates for bone tissue engineering applications.

Bioactive/Natural Polymeric Scaffolds Loaded with Ciprofloxacin for Treatment of Osteomyelitis

Local delivery of antibiotic into injured bone is a demand. In this work, different scaffolds of chitosan (C) with or without bioactive glass (G) were prepared using the freeze-drying technique in 2:1, 1:1, and 1:2 weight ratios. Chitosan scaffolds and selected formulas of chitosan to bioglass were loaded with ciprofloxacin in 5%, 10%, and 20% w/w. Scaffold morphology showed an interconnected porous structure, where the glass particles were homogeneously dispersed in the chitosan matrix. The kinetic study confirmed that the scaffold containing 1:2 weight ratio of chitosan to glass (CG12) showed optimal bioactivity with good compromise between Ca and P uptake capacities and Si release rate. Chitosan/bioactive glass scaffolds showed larger t ₅₀ values indicating less burst drug release followed by a sustained drug release profile compared to that of chitosan scaffolds. The cell growth, migration, adhesion, and invasion were enhanced onto CG12 scaffold surfaces. Samples of CG12 scaffolds with or without 5% drug induced vascular endothelial growth factor (VEGF), while those containing 10% drug diminished VEGF level. Only CG12 induced the cell differentiation (alkaline phosphatase activity). In conclusion, CG12 containing 5% drug can be considered a biocompatible carrier which would help in the localized osteomyelitis treatment.

Fabrication of Gelatin-Based Electrospun Composite Fibers for Anti-Bacterial Properties and Protein Adsorption

A major goal of biomimetics is the development of chemical compositions and structures that simulate the extracellular matrix. In this study, gelatin-based electrospun composite fibrous membranes were prepared by electrospinning to generate bone scaffold materials. The gelatin-based multicomponent composite fibers were fabricated using co-electrospinning, and the composite fibers of chitosan (CS), gelatin (Gel), hydroxyapatite (HA), and graphene oxide (GO) were successfully fabricated for multi-function characteristics of biomimetic scaffolds. The effect of component concentration on composite fiber morphology, antibacterial properties, and protein adsorption were investigated. Composite fibers exhibited effective antibacterial activity against Staphylococcus aureus and Escherichia coli. The study observed that the composite fibers have higher adsorption capacities of bovine serum albumin (BSA) at pH 5.32-6.00 than at pH 3.90-4.50 or 7.35. The protein adsorption on the surface of the composite fiber increased as the initial BSA concentration increased. The surface of the composite reached adsorption equilibrium at 20 min. These results have specific applications for the development of bone scaffold materials, and broad implications in the field of tissue engineering.

Fabrication and characterization of novel nano-biocomposite scaffold of chitosan-gelatin-alginate-hydroxyapatite for bone tissue engineering

A novel nano-biocomposite scaffold was fabricated in bead form by applying simple foaming method, using a combination of natural polymers-chitosan, gelatin, alginate and a bioceramic-nano-hydroxyapatite (nHAp). This approach of combining nHAp with natural polymers to fabricate the composite scaffold, can provide good mechanical strength and biological property mimicking natural bone. Environmental scanning electron microscopy (ESEM) images of the nano-biocomposite scaffold revealed the presence of interconnected pores, mostly spread over the whole surface of the scaffold. The nHAp particulates have covered the surface of the composite matrix and made the surface of the scaffold rougher. The scaffold has a porosity of 82% with a mean pore size of 112±19.0μm. Swelling and degradation studies of the scaffold showed that the scaffold possesses excellent properties of hydrophilicity and biodegradability. Short term mechanical testing of the scaffold does not reveal any rupturing after agitation under physiological conditions, which is an indicative of good mechanical stability of the scaffold. In vitro cell culture studies by seeding osteoblast cells over the composite scaffold showed good cell viability, proliferation rate, adhesion and maintenance of osteoblastic phenotype as indicated by MTT assay, ESEM of cell-scaffold construct, histological staining and gene expression studies, respectively. Thus, it could be stated that the nano-biocomposite scaffold of chitosan-gelatin-alginate-nHAp has the paramount importance for applications in bone tissue-engineering in future regenerative therapies.

Differentiation of human endometrial stem cells into endothelial-like cells on gelatin/chitosan/bioglass nanofibrous scaffolds

The capacity of gelatin/chitosan/bioactive glass nanopowders (GEL/CS/BGNPs) scaffolds was investigated for increasing human endometrial stem cells (hEnSCs) differentiation into the endothelial cells in the presence of angiogenic factors. GEL/CS nanofibrous scaffold with different contents of BGNPs were fabricated and assessed. Expression of endothelial markers (CD31, vascular endothelial cadherin (VE-cadherin), and KDR) in differentiated cells was evaluated. Results showed the diameter of nanofiber increases with decreasing the BG content in GEL/CS scaffolds. Moreover, in vitro study indicated that the GEL/CS/BGNPs scaffold with 1.5% BGNPs content provided a suitable three-dimensional structure for endothelial cells differentiation. Thus, the GEL/CS/BGNPs scaffold can be recommended for blood vessels repair.

Hybrid hydroxyapatite nanoparticles-loaded PCL/GE blend fibers for bone tissue engineering

In order to augment bone formation, a new biodegradable scaffold system was fabricated using different ratios of hydroxyapatite (HAp) blended with synthetic polymer polycaprolactone (PCL) and natural polymer gelatin (GE) followed by electrospinning method. Three different concentrations of HAp were used in PCL/GE to obtain a blend of 10, 30, and 50% (w/v) HAp-PCL/GE. These HAp-loaded PCL/GE blends were then compared with PCL/GE blends by different mechanical and biological in vitro and in vivo studies to understand the applicability of the system. Scanning electron microscopy, X-ray diffraction analysis, and tensile strength measurement were done to obtain physical properties. Fifty Percent HAp-PCL/GE blends possessed the highest mechanical strength. In vitro cytotoxicity and proliferation of osteoblast cells on the PCL/GE and HAp-PCL/GE scaffolds were examined and shown that addition of HAp in PCL/GE was beneficial by increasing cell viability (>85%) proliferation and cell-surface attachment. Expression of collagen and osteopontin was also found higher in 50% HAp-PCL/GE blends than the others. On the other hand, in vivo bone formation was examined using rat models and increased bone formation was observed in 50% HAp-PCL/GE blends within 6 weeks. Based on the combined results of this study, HAp-PCL/GE membranes were found to hold great promise for use in tissue engineering applications, especially in bone tissue engineering.

Fabrication and evaluation of chitosan-gelatin based buckling implant for retinal detachment surgery

The traditional nonabsorbable silicone buckling implant (buckle) may cause some long-term complications when it is used in the retinal detachment surgery. In this study we fabricated a chitosan-gelatin based buckling implant to replace the traditional one. We evaluated its biocompatibility with human scleral fibroblasts (HSF) in vitro and its cytotoxicity with L929 cell. To evaluate elasticity and hardness of the blends buckle, the mechanical properties of the chitosan-gelatin buckle were compared with the traditional silicone buckle. The light and electron microscopy coupled with immunocytochemistry demonstrated that chitosan-gelatin blends supported the survival and growth of primarily cultured HSF without significant cytotoxic effects. MTT analysis and cell cycle analysis indicated that chitosan-gelatin blends promoted the proliferation of HSF. A preliminary in vivo implantation test indicated that chitosan-gelatin buckling implant were compatible with the surrounding tissue. The results collectively demonstrated that chitosan-gelatin blends could be a candidate biodegradable material for scleral buckling surgery.

Application of spectroscopic methods for structural analysis of chitin and chitosan

Chitin, the second most important natural polymer in the world, and its N-deacetylated derivative chitosan, have been identified as versatile biopolymers for a broad range of applications in medicine, agriculture and the food industry. Two of the main reasons for this are firstly the unique chemical, physicochemical and biological properties of chitin and chitosan, and secondly the unlimited supply of raw materials for their production. These polymers exhibit widely differing physicochemical properties depending on the chitin source and the conditions of chitosan production. The presence of reactive functional groups as well as the polysaccharide nature of these biopolymers enables them to undergo diverse chemical modifications. A complete chemical and physicochemical characterization of chitin, chitosan and their derivatives is not possible without using spectroscopic techniques. This review focuses on the application of spectroscopic methods for the structural analysis of these compounds.

Organic/Inorganic bioactive materials Part III: in vitro bioactivity of gelatin/silicocarnotite hybrids

In this work we present our experimental results on synthesis, structure evolution and in vitro bioactivity assessment of new gelatin/silicocarnotite hybrid materials. The hybrids were obtained by diluting gelatin (G) and silicocarnotite (S) ceramic powder with G:S ratios of 75:25 and 25:75 wt.% in hot (40°C) water. The hybrids were characterized using XRD, FTIR, SEM/EDS and XPS. FTIR depicts that the “red shift” of amide I and COO− could be attributed to the fact that the gelatin prefers to chelate Ca2+ from S. The growth of calcium phosphates on the surface of the hybrids synthesized and then immersed in 1.5 SBF for 3 days was studied by using of FTIR, XRD and SEM/EDS. According to FTIR results, after an immersion of 3 days, A and B-type CO3HA can be observed on the surface. XRD results indicate the presence of hydroxyapatite with well defined crystallinity. SEM/EDS of the precipitated layers show the presence of CO3HA and amorphous calcium phosphate on the surface of samples with different G/S content when immersed in 1.5 SBF. XPS of the G/S hybrid with 25:75 wt.% proved the presence of Ca-deficient hydroxyapatite after an in vitro test for 3 days.