Preparation and characterization of collagen–hydroxyapatite/pectin composite

Material matters: exploring the interplay between natural biomaterials and host immune system

Biomaterials are widely used for various medical purposes, for instance, implants, tissue engineering, medical devices, and drug delivery systems. Natural biomaterials can be obtained from proteins, carbohydrates, and cell-specific sources. However, when these biomaterials are introduced into the body, they trigger an immune response which may lead to rejection and failure of the implanted device or tissue. The immune system recognizes natural biomaterials as foreign substances and triggers the activation of several immune cells, for instance, macrophages, dendritic cells, and T cells. These cells release pro-inflammatory cytokines and chemokines, which recruit other immune cells to the implantation site. The activation of the immune system can lead to an inflammatory response, which can be beneficial or detrimental, depending on the type of natural biomaterial and the extent of the immune response. These biomaterials can also influence the immune response by modulating the behavior of immune cells. For example, biomaterials with specific surface properties, such as charge and hydrophobicity, can affect the activation and differentiation of immune cells. Additionally, biomaterials can be engineered to release immunomodulatory factors, such as anti-inflammatory cytokines, to promote a tolerogenic immune response. In conclusion, the interaction between biomaterials and the body's immune system is an intricate procedure with potential consequences for the effectiveness of therapeutics and medical devices. A better understanding of this interplay can help to design biomaterials that promote favorable immune responses and minimize adverse reactions.

Effect of pectin on the crystallization of strontium substituted HA for bone reconstruction application

The biomacropolymers of bone extracellular matrix (ECM) guide the growth of hydroxyapatite (HA) with various ionic substitutions. Pectin, a plant polysaccharide with chemical similarities to ECM, was investigated for its potential to promote the crystallization of strontium-substituted HA (SH). The influence of pectin (0.5 and 1.0 wt%) on the in situ mineralization of SH (10 and 30 mol% calcium substitution with strontium) was studied. The preferential affinity of pectin to strontium over calcium favoured the incorporation of strontium in apatite, decreased crystal size (18.85-26.22 nm) and retained more pectin residues (8-16%). The residual pectin strongly interacted with small SH particles, resulting in high microhardness (0.43-0.85 GPa) and high surface charge (-32.1 to -30.3 mV), while weak interaction with large HA particles resulted in low microhardness (0.15-0.25 GPa) and low surface charge (-35.4 to -34.6 mV). The in vitro cellular study using human osteoblast-like MG-63 cells demonstrated that inorganic size and material crystallinity play a vital role in regulating osteogenesis. The study suggests that the synchronization of low pectin concentration (0.5 wt%) and high strontium substitution in HA (30 mol%) offers the desired microhardness and in vitro osteogenic properties to emulate natural bone.

Pectin-based bioinks for 3D models of neural tissue produced by a pH-controlled kinetics

Introduction: In the view of 3D-bioprinting with cell models representative of neural cells, we produced inks to mimic the basic viscoelastic properties of brain tissue. Moving from the concept that rheology provides useful information to predict ink printability, this study improves and expands the potential of the previously published 3D-reactive printing approach by introducing pH as a key parameter to be controlled, together with printing time. Methods: The viscoelastic properties, printability, and microstructure of pectin gels crosslinked with CaCO₃ were investigated and their composition was optimized (i.e., by including cell culture medium, HEPES buffer, and collagen). Different cell models representative of the major brain cell populations (i.e., neurons, astrocytes, microglial cells, and oligodendrocytes) were considered. Results and Discussion: The outcomes of this study propose a highly controllable method to optimize the printability of internally crosslinked polysaccharides, without the need for additives or post-printing treatments. By introducing pH as a further parameter to be controlled, it is possible to have multiple (pH-dependent) crosslinking kinetics, without varying hydrogel composition. In addition, the results indicate that not only cells survive and proliferate following 3D-bioprinting, but they can also interact and reorganize hydrogel microstructure. Taken together, the results suggest that pectin-based hydrogels could be successfully applied for neural cell culture.

Potential of pectin for biomedical applications: a comprehensive review

Pectin is a polysaccharide extracted from various plants, such as apples, oranges, lemons, and it possesses some beneficial effects on human health, including being hypoglycemic and hypocholesterolemic. Therefore, pectin is used in various pharmaceutical and biomedical applications. Meanwhile, its low mechanical strength and fast degradation rate limit its usage as drug delivery devices and tissue engineering scaffolds. To enhance these properties, it can be modified or combined with other organic molecules or polymers and/or inorganic compounds. These materials can be prepared as nano sized drug carriers in the form of spheres, capsules, hydrogels, self assamled micelles, etc., for treatment purposes (mostly cancer). Different composites or blends of pectin can also be produced as membranes, sponges, hydrogels, or 3D printed matrices for tissue regeneration applications. This review is concentrated on the properties of pectin based materials and focus especially on the utilization of these materials as drug carriers and tissue engineering scaffolds, including 3D printed and 3D bioprinted systems covering the studies in the last decade and especially in the last 5 years.

Gamma sterilization of collagen/hydroxyapatite composites: Validation and radiation effects

In this work, gamma sterilization was validated, and the impact of this sterilization process on collagen/hydroxyapatite (Col/HAp) composites was investigated. It has been already recognized that the improper sterilization of healthcare products may lead to infection and mortality/morbidity issues in patients. Gamma sterilization has emerged as a promising sterilization method because it shows advantages such as low cost, a small increase in temperature of irradiated materials, and no production of toxic residues. Moreover, gamma rays can reach the products even when contained in sealed packages. The dose of gamma radiation applied in this study ranged from 17.5 to 50 kGy. The studied samples were examined by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), thermogravimetry (TG), and differential scanning calorimetry (DSC). No apparent effect of gamma radiation on HAp was observed even when doses as high as 50 kGy were applied. On the other hand, Col was greatly affected by gamma radiation, displaying cross-linking and degradation after sterilization. These structural changes may alter Col's properties, which could, in turn, impact its medical use. As a consequence, it is strongly recommended that the irradiation dose used to sterilize the Col/HAp composites shall be kept as low as possible to mitigate the structural changes induced in Col. It was noticed that a radiation dose of 17.5 kGy was sufficient to sterilize the examined samples because a sterility assurance level (SAL) below 10^-6 was detected. Although dramatic structural changes were observed in Col when this dose was applied, the sterilized samples showed no toxicity to human mesenchymal stem cells. Based on these results, we established a VD_Max of 17.5 kGy for Col/HAp-based healthcare products.

Review of the Applications of Biomedical Compositions Containing Hydroxyapatite and Collagen Modified by Bioactive Components

Regenerative medicine is becoming a rapidly evolving technique in today's biomedical progress scenario. Scientists around the world suggest the use of naturally synthesized biomaterials to repair and heal damaged cells. Hydroxyapatite (HAp) has the potential to replace drugs in biomedical engineering and regenerative drugs. HAp is easily biodegradable, biocompatible, and correlated with macromolecules, which facilitates their incorporation into inorganic materials. This review article provides extensive knowledge on HAp and collagen-containing compositions modified with drugs, bioactive components, metals, and selected nanoparticles. Such compositions consisting of HAp and collagen modified with various additives are used in a variety of biomedical applications such as bone tissue engineering, vascular transplantation, cartilage, and other implantable biomedical devices.

Synthesis of nanohydroxyapatite/collagen-loaded fucoidan-based composite hydrogel for drug delivery to gastrointestinal cancer cells

The present study aims to evaluate the synthesis of nanohydroxyapatite/collagen-loaded fucoidan-based composite hydrogel and characterized its physico-chemical properties for targeted drug delivery to gastrointestinal cancer cells. The nanomaterial is fabricated and characterized as small spherical nanosheets with a high thermal stability by using Fourier transform infrared (FTIR) analysis, X-ray diffraction (XRD), Thermogravimetric analysis (TGA), UV-vis spectrophotometry (UV-vis), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). in vitro cytotoxicity, BrdU cell proliferation, and scratch assays demonstrate that the nanohydroxyapatite/collagen-loaded fucoidan-based nanomaterial exhibits non-toxicity and increases cell proliferation and migration. in vitro free radical scavenging assays confirm that the fabricated nanomaterial inhibits reactive oxygen species and generates singlet oxygen radicals in the gastrointestinal cancer cells by. The current findings suggest that the proposed nanomaterial can be a potential carrier for the targeted drug delivery to the gastrointestinal cancer cells.

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.

Bioactivity reinforced surface patch bound collagen-pectin hydrogel

In this report, we discuss the design of a novel collagen/pectin (CP) hybrid composite hydrogel (CPBG) containing in-situ mineralized bioactive glass (BG) particles to simulate an integrative 3D cell environment. Systematic analysis of the CP sol revealed collagen and pectin molecules interacted regardless of both possessing similar net negative charge through the mechanism of surface patch binding interaction. Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA) confirmed this associative interaction which resulted in the formation of a hybrid crosslinked network with the BG nanoparticles acting as pseudo crosslink junctions. Scanning Electron Microscopy (SEM), Energy Dispersive X-Ray Analysis (EDAX) and Transmission Electron Microscopy (TEM) results confirmed uniform mineralization of BG particles, and their synergetic interaction with the network. The in-vitro bioactivity tests on CPBG indicated the formation of bone-like hydroxyapatite (Ca₁₀(PO₄)₆(OH)₂) microcrystals on its surface after interaction with simulated body fluid. This hydrogel was loaded with a model antifungal drug amphotericin-B (AmB) and tested against Candida albicans. The AmB release kinetics from the hydrogel followed the Fickian mechanism and showed direct proportionality to gel swelling behavior. Rheological analysis revealed the viscoelastic compatibility of CPBG for the mechanical load bearing applications. Cell viability tests indicated appreciable compatibility of the hydrogel against U2OS and HaCaT cell lines. FDA/PI on the hydrogel portrayed preferential U2OS cell adhesion on hydrophobic hydroxyapatite layer compared to hydrophilic surfaces, thereby promising the regeneration of both soft and hard tissues.

Influence of gelatin and collagen incorporation on peroxidase-mediated injectable pectin-based hydrogel and bioactivity of fibroblasts

Pectin has recently attracted increasing attention for biomedical and pharmaceutical applications. Due to the lack of adhesion molecules in polysaccharides, phenolic hydroxyl conjugated gelatin was added to enzymatically-gellable peroxidase-modified pectin derivative and compared with phenolic hydroxyl -pectin/collagen. Both pectin and gelatin were modified by tyramine hydrochloride in the presence of EDC/NHS. The phenolic hydroxyl -pectin/phenolic hydroxyl -gelatin, phenolic hydroxyl-pectin/collagen, and phenolic hydroxyl -pectin hydrogels were prepared using horseradish peroxidase and hydrogen peroxide_. The hydrogels were characterized by gelation time analysis. Morphology, enzymatic biodegradation, mechanical and swelling properties as well as water vapor transmission rate were also evaluated. Fibroblasts were cultured for 7 days, and the survival rate was evaluated using conventional MTT assay. Hydrogels composed of Ph-pectin/Ph-gelatin showed decreased biodegradation rate, and WVTR and further improved mechanical performance in comparison with other groups. Both phenolic hydroxyl -pectin/collagen and phenolic hydroxyl -pectin/phenolic hydroxyl -gelatin hydrogels exhibited porous structures. The hydrogels composed of collagen promoted cell survival rate 1.4 and 3.5 times compared to phenolic hydroxyl -gelatin and phenolic hydroxyl -pectin based hydrogels at the end of 7 days, respectively (p < 0.001). The study demonstrated the potential of enzymatically-gellable pectin-based hydrogels as cost-effective frameworks for use in tissue engineering applications.

Biomimetic Composite Scaffold With Phosphoserine Signaling for Bone Tissue Engineering Application

In guided bone tissue engineering, successful ingrowth of MSCs depends primarily on the nature of the scaffold. It is well-known that only seconds after implantation, biomaterials are coated by a layer of adsorbed proteins/peptides which modulates the subsequent cell/scaffold interactions, especially at early times after implantation. In this work, nanohydroxyapatite and collagen based composite materials (Coll/nanoHA) were modified with phosphorylated amino acid (O-phospho-L-serine-OPS) to mimic bone tissue, and induce cell differentiation. The choice for this phosphorylated amino acid is due to the fact that osteopontin is a serine-rich glycol-phosphoprotein and has been associated to the early stages of bone formation, and regeneration. Several concentrations of OPS were added to the Coll/nanoHA scaffold and physico-chemical, mechanical, and in vitro cell behavior were evaluated. Afterwards, the composite scaffold with stronger mechanical and best cellular behavior was tested in vivo, with or without previous in vitro culture of human MSC's (bone tissue engineering). The OPS signaling of the biocomposite scaffolds showed similar cellular adhesion and proliferation, but higher ALP enzyme activity (HBMSC). In vivo bone ectopic formation studies allowed for a thorough evaluation of the materials for MSC's osteogenic differentiation. The OPS-scaffolds results showed that the material could modulated mesenchymal cells behavior in favor of osteogenic differentiation into late osteoblasts that gave raised to their ECM with human bone proteins (osteopontin) and calcium deposits. Finally, OPS-modified scaffolds enhanced cell survival, engraftment, migration, and spatial distribution within the 3D matrix that could be used as a cell-loaded scaffold for tissue engineering applications and accelerate bone regeneration processes.

Synthesis and appraisal of a hydroxyapatite/pectin hybrid material for zinc removal from water

A simple method to modify hydroxyapatite and pectin into an efficient zinc sorbent was investigated. Process and formulation modifications enabled the formation of a flower-like hydroxyapatite/pectin hybrid material. The hybrid material was characterized with scanning electron microscopy, elemental analysis, and zeta potential tests. Sorption data were analyzed with different kinetic and isotherm models. The results showed that the pseudo-second order kinetic model and two-staged isotherm curves with Langmuir at the first stage and a Freundlich model the at second stage could best describe the zinc sorption on the hybrid. The maximum experimental sorption capacity was 330.4 mg Zn2+ per gram of sorbent, which was obtained with an initial concentration of 260 mg L-1 Zn2+ at pH 5.0. pH monitoring and Zeta potential tests suggested surface complexation and electrostatic attraction were fundamental in the zinc sorption process.

A porous collagen-carboxymethyl cellulose/hydroxyapatite composite for bone tissue engineering by bi-molecular template method

Inspired by the mechanism of bone formation, a porous collagen-carboxymethyl cellulose/hydroxyapatite (Col-CMC/HA) composite was designed and fabricated using a biomimetic template of Col and CMC protein-polysaccharide bi-molecules. The morphology, composition and physical properties of Col-CMC/HA composites were characterized systematically. It was found that the nano-HA homogenously distributed on the surface of Col-CMC bi-templates while the composite presented 3D porous structure with pore size from 100 μm to 300 μm. The porosities of composites were located at the range of 71%-85%. Besides, the compressive strength of composites was highly depended on the ratio of Col to CMC in the organic template. The optimized composite in respect to physical properties showed a compressive strength as high as 7.06 MPa, quite close to that of natural bone. The high relative growth rate of wild-type mouse embryonic fibroblasts cells was found for the composite, indicating a good biocompatibility. The organic-inorganic composite also behaved good in collagenase resistance and could be biodegraded in 8 weeks, with about 50% of initial weight left at the ratio of Col to CMC of 1:9. The results demonstrated that the Col-CMC/HA composite by bi-molecular template method was a rational and safe method to prepare biomaterials with tunable properties.

Interpenetrating network gelatin methacryloyl (GelMA) and pectin-g-PCL hydrogels with tunable properties for tissue engineering

The design of new hydrogel-based biomaterials with tunable physical and biological properties is essential for the advancement of applications related to tissue engineering and regenerative medicine. For instance, interpenetrating polymer network (IPN) and semi-IPN hydrogels have been widely explored to engineer functional tissues due to their characteristic microstructural and mechanical properties. Here, we engineered IPN and semi-IPN hydrogels comprised of a tough pectin grafted polycaprolactone (pectin-g-PCL) component to provide mechanical stability, and a highly cytocompatible gelatin methacryloyl (GelMA) component to support cellular growth and proliferation. IPN hydrogels were formed by calcium ion (Ca2+)-crosslinking of pectin-g-PCL chains, followed by photocrosslinking of the GelMA precursor. Conversely, semi-IPN networks were formed by photocrosslinking of the pectin-g-PCL and GelMA mixture, in the absence of Ca2+ crosslinking. IPN and semi-IPN hydrogels synthesized with varying ratios of pectin-g-PCL to GelMA, with and without Ca2+-crosslinking, exhibited a broad range of mechanical properties. For semi-IPN hydrogels, the aggregation of microcrystalline cores led to formation of hydrogels with compressive moduli ranging from 3.1 to 10.4 kPa. For IPN hydrogels, the mechanistic optimization of pectin-g-PCL, GelMA, and Ca2+ concentrations resulted in hydrogels with comparatively higher compressive modulus, in the range of 39 kPa-5029 kPa. Our results also showed that IPN hydrogels were cytocompatible in vitro and could support the growth of three-dimensionally (3D) encapsulated MC3T3-E1 preosteoblasts in vitro. The simplicity, technical feasibility, low cost, tunable mechanical properties, and cytocompatibility of the engineered semi-IPN and IPN hydrogels highlight their potential for different tissue engineering and biomedical applications.

From waste to high-value product: Jackfruit peel derived pectin/apatite bionanocomposites for bone healing applications

Public requirements encouraged by the current asset framework drive industry to expand its general effectiveness by enhancing existing procedures or finding new uses for waste. Thus, the aim of this study was the isolation, fabrication, and characterization of pectin derived from jackfruit (Artocarpus heterophyllus) peels and the generation of hybrid of pectin (P)/apatite (HA) (P/HA) bionanocomposites. In this process, the natural pectin polymer derived from the peel of jackfruits was used in different concentrations for the fabrication of HA bionanocomposites. Characterization of the isolated pectin and bionanocomposites samples was performed with ¹H NMR and ¹³C NMR, FTIR, XRD, SEM-EDX, and HR-TEM. Cytocompatibility, ALP, fibroblast stem cells, anti-inflammatory and cell adhesion testing of the fabricated bionanocomposites was showed good biocompatibility. Our results signify that the fabricated bionanocomposites might be applicable as bone graft materials.

Biocompatible 3D Matrix with Antimicrobial Properties

The aim of this study was to develop, characterize and assess the biological activity of a new regenerative 3D matrix with antimicrobial properties, based on collagen (COLL), hydroxyapatite (HAp), β-cyclodextrin (β-CD) and usnic acid (UA). The prepared 3D matrix was characterized by Scanning Electron Microscopy (SEM), Fourier Transform Infrared Microscopy (FT-IRM), Transmission Electron Microscopy (TEM), and X-ray Diffraction (XRD). In vitro qualitative and quantitative analyses performed on cultured diploid cells demonstrated that the 3D matrix is biocompatible, allowing the normal development and growth of MG-63 osteoblast-like cells and exhibited an antimicrobial effect, especially on the Staphylococcus aureus strain, explained by the particular higher inhibitory activity of usnic acid (UA) against Gram positive bacterial strains. Our data strongly recommend the obtained 3D matrix to be used as a successful alternative for the fabrication of three dimensional (3D) anti-infective regeneration matrix for bone tissue engineering.