Preparation and characterization of cockle shell aragonite nanocomposite porous 3D scaffolds for bone repair

Coaxial Electrospun Polycaprolactone/Gelatin Nanofiber Membrane Loaded with Salidroside and Cryptotanshinone Synergistically Promotes Vascularization and Osteogenesis

Background

Salidroside (SAL) is the most effective component of Rhodiola rosea, a traditional Chinese medicine. Cryptotanshinone (CT) is the main fat-soluble extract of Salvia miltiorrhiza, exhibiting considerable potential for application in osteogenesis. Herein, a polycaprolactone/gelatin nanofiber membrane loaded with CT and SAL (PSGC membrane) was successfully fabricated via coaxial electrospinning and characterized.

Methods and Results

This membrane capable of sustained and controlled drug release was employed in this study. Co-culturing the membrane with bone marrow mesenchymal stem cells and human umbilical vein endothelial cells revealed excellent biocompatibility and demonstrated osteogenic and angiogenic capabilities. Furthermore, drug release from the PSGC membrane activated the Wnt/β-catenin signaling pathway and promoted osteogenic differentiation and vascularization. Evaluation of the membrane's vascularization and osteogenic capacities involved transplantation onto a rat's subcutaneous area and assessing rat cranium defects for bone regeneration, respectively. Microcomputed tomography, histological tests, immunohistochemistry, and immunofluorescence staining confirmed the membrane's outstanding angiogenic capacity two weeks post-operation, with a higher incidence of osteogenesis observed in rat cranial defects eight weeks post-surgery.

Conclusion

Overall, the SAL- and CT-loaded coaxial electrospun nanofiber membrane synergistically enhances bone repair and regeneration.

Green Ca-source of cockle shells converted to calcium acetate for environmental sustainability

This work aimed to synthesize and characterize the calcium acetate monohydrate (Ca(CH3COO)2·H2O) from the exothermic reaction between CaCO3 powder derived from cockle shells with three different acetic acids (8, 10, and 12 mol L-1) concentrations by the rapid and easy process without pH and temperature control to lead to cheap chemical production. The physicochemical characteristics of all synthesized Ca(CH3COO)2·H2O samples are investigated based on the chemical compositions, crystal structures, vibrational characteristics, morphologies, and thermal behavior to confirm the target compound. A suitable concentration of 10 mol L-1 CH3COOH was chosen to produce Ca(CH3COO)2·H2O with the highest yield (96.30 %), maximum calcium content (96.2 % CaO) with lower impurities, and time consumption of 17 h. The calcium acetate product obtained from cockle shells in this work shows differences in thermal stability, morphological structure purity, %yield, and metal contamination with those reported obtained from other sources and another shell type in the previous work. This research investigates the transformation of cockle shell waste into CaCO3 for the production of calcium acetate, aiming to address environmental sustainability concerns by reducing the use of calcium ore resources and greenhouse gas emissions.

Potential use of a bone tissue engineering scaffold based on electrospun poly (ɛ-caprolactone) - Poly (vinyl alcohol) hybrid nanofibers containing modified cockle shell nanopowder

Today, the construction of scaffolds promoting the differentiation of stem cells is an intelligent innovation that accelerates the differentiation toward the target tissue. The use of calcium and phosphate compounds is capable of elevating the precision and efficiency of the osteogenic differentiation of stem cells. In this research, osteoconductive electrospun poly (ɛ-caprolactone) (PCL) - poly (vinyl alcohol) (PVA) hybrid nanofibrous scaffolds containing modified cockle shell (CS) nanopowder were prepared and investigated. In this regard, the modified CS nanopowder was prepared by grinding and modifying with phosphoric acid, and it was then added to PVA nanofibers at different weight percentages. Based on the SEM images, the optimum content of the modified CS nanopowder was set at 7 wt %, since reaching the threshold of agglomeration restricted this incorporation. In the second step, the PVA-CS7 nanofibrous sample was hybridized with different PCL ratios. Concerning the hydrophilicity and mechanical strength, the sample named PCL50-PVA50-CS7 was ultimately selected as the optimized and suitable candidate scaffold for bone tissue application. The accelerated hydrolytic degradation of the sample was also studied by FTIR and SEM analyses, and the results confirmed that the mineral deposits of CS are available approximately 7 days for mesenchymal stem cells. Moreover, Alizarin red staining illustrated that the presence of CS in the PCL50-PVA50-CS7 hybrid nanofibrous scaffold may potentially lead to an increase in calcium deposits with high precipitates, authenticating the differentiation of stem cells towards osteogenic cells.

Utilization of cockle shell powder as an adsorbent to remove phosphorus-containing wastewater

The paper demonstrates the capability of using cockle shells as an adsorbent for phosphorus removal from simulated petrochemical wastewater, focusing on the actual condition of the petrochemical facultative pond. In this study, the physicochemical properties of shell powder were determined, such as the functional groups, surface morphology, crystalline structure, and surface area using FTIR, SEM, EDX, XRD, and BET. It was observed that the optimum conditions for effective phosphorus removal are under the presence of rotational speed (125 rpm), higher dosage (7 g/L), and larger surface area (smaller particle size) of the shell powder. Fine powder achieved up to 52.27% of phosphorus removal after 40 min compared to coarse powder which could only give 16.67% removal. Additionally, calcined shell powder demonstrated a higher phosphorus removal rate, i.e., up to 62.37%, compared to raw shell powders. The adsorption isotherm was studied using Langmuir and Freundlich models, but the isothermal data fit better for the Freundlich model (R² = 0.9836). Overall, this study has successfully generated a greener and low-cost adsorbent.

Synthesis and Characterization of Porous CaCO3 Vaterite Particles by Simple Solution Method

Appropriately engineered CaCO3 vaterite has interesting properties such as biodegradability, large surface area, and unique physical and chemical properties that allow a variety of uses in medical applications, mainly in dental material as the scaffold. In this paper, we report the synthesis of vaterite from Ca(NO3)2·4H2O without porogen to obtain a highly pure and porous microsphere for raw material of calcium phosphate as the scaffold in our future development. CaCO3 properties were investigated at two different temperatures (20 and 27 °C) and stirring speeds (800 and 1000 rpm) and at various reaction times (5, 10, 15, 30, and 60 min). The as-prepared porous CaCO3 powders were characterized by FTIR, XRD, SEM, TEM, and BET methods. The results showed that vaterite with purity 95.3%, crystallite size 23.91 nm, and porous microsphere with lowest pore diameter 3.5578 nm was obtained at reaction time 30 min, temperature reaction 20 °C, and stirring speed 800 rpm. It was emphasized that a more spherical microsphere with a smaller size and nanostructure contained multiple primary nanoparticles received at a lower stirring speed (800 rpm) at the reaction time of 30 min. One of the outstanding results of this study is the formation of the porous vaterite microsphere with a pore size of ~3.55 nm without any additional porogen or template by using a simple mixing method.

Progress in Modern Marine Biomaterials Research

The growing demand for new, sophisticated, multifunctional materials has brought natural structural composites into focus, since they underwent a substantial optimization during long evolutionary selection pressure and adaptation processes. Marine biological materials are the most important sources of both inspiration for biomimetics and of raw materials for practical applications in technology and biomedicine. The use of marine natural products as multifunctional biomaterials is currently undergoing a renaissance in the modern materials science. The diversity of marine biomaterials, their forms and fields of application are highlighted in this review. We will discuss the challenges, solutions, and future directions of modern marine biomaterialogy using a thorough analysis of scientific sources over the past ten years.

Synthesis and Characterization of Spherical Calcium Carbonate Nanoparticles Derived from Cockle Shells

Cockle shells are a natural reservoir of calcium carbonate (CaCO3), which is widely used in bone repair, tissue scaffolds, and the development of advanced drug delivery systems. Although many studies report on the preparation of CaCO3, the development of a nanosized spherical CaCO3 precursor for calcium oxide (CaO) that is suitable to be incorporated in dental material was scarce. Therefore, this study aimed to synthesize a nanosized spherical CaCO3 precursor for CaO derived from cockle shells using a sol–gel method. Cockle shells were crushed to powder form and mixed with hydrochloric acid, forming calcium chloride (CaCl2). Potassium carbonate (K2CO3) was then fed to the diluted CaCl2 to obtain CaCO3. The effect of experimental parameters on the morphology of CaCO3, such as volume of water, type of solvents, feeding rate of K2CO3, and drying method, were investigated using field-emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffractometry (XRD), Brunauer–Emmett–Teller surface area analysis, and thermogravimetric analysis. Optimized CaCO3 was then calcined to form CaO. XRD analysis of CaCO3 nanoparticles was indicative of the formation of a calcite phase. The well-structured spherical shape of CaCO3 was obtained by the optimum condition of the addition of 50 mL of water into CaCl2 in ethanolic solution with a 1 h feeding rate of K2CO3. Less agglomeration of CaCO3 was obtained using a freeze-drying technique with the surface area of 26 m2/g and average particle size of 39 nm. Spherical shaped nanosized CaO (22–70 nm) was also synthesized. The reproducibility, low cost, and simplicity of the method suggest its potential applications in the large-scale synthesis of the nanoparticles, with spherical morphology in an industrial setting.

Cockle shell-derived aragonite calcium carbonate nanoparticle for targeting cancer and breast cancer stem cells

Cockle shell-derived aragonite calcium carbonate nanoparticles (CACNP) have demonstrated prospect as nano-sized drug carriers for targeting cancer cells. CACNP is biocompatible, biodegradable and its biomaterial is readily available and is of low cost. In addition, CACNP is highly porous, has a large surface area which confer a high loading capacity. The pH-dependent release properties as well as its potential for surface functionalization with targeting agents make CACNP useful in passive and active targeting of cancer cells and cancer stem cells. In this article, we reviewed the current state of CACNP as nano-sized drug carrier for targeting cancer cells, cancer stem cells and its biocompatibility.

Utilization of Waste Grooved Razor Shell (GRS) as a Catalyst in Biodiesel Production from Refined and Waste Cooking Oils

Biodiesel is a potential alternative for fossil fuel. However, its large-scale application is held up by the disadvantage of a homogenous process, the scarce availability of raw materials and the production cost, which is higher than for fossil diesel. In this work, biodiesel production was carried out using both refined and used cooking oils. The process was investigated in a batch reactor, in the presence of CaO as a heterogeneous catalyst prepared by the calcination of the natural Waste Grooved Razor Shell (GRS). Characterizations by X-Ray Diffraction (XRD) and Thermal Gravimetric (TG)/Differential Thermal Analysis (DTA) showed that the as-received GRS consists of aragonite, (i.e., CaCO3) as the main component and of water and organic matter in a lower amount. After calcination at 900 °C, CaO was formed as the only crystalline phase. The effects of several experimental parameters in the transesterification reactions were studied, and their impact on the produced biodiesel properties was investigated. The studied variables were the methanol/oil molar ratio, the catalyst weight percentage (with respect to the oil mass), the calcination temperature of the parent GRS and the recycling and regeneration of the catalyst. The physico-chemical and fuel properties, i.e., viscosity, density and acid value of used oils and of the produced biodiesel, were determined by conventional methods (American Society for Testing and Materials (ASTM) methods) and compared with the European standards of biodiesel. The optimal identified conditions were the following: the use of a 15:1 methanol/oil molar ratio and 5 wt% of CaO with respect to the oil mass. After 3 h of reaction at 65 °C, the biodiesel yield was equal to 94% and 99% starting from waste and refined oils, respectively.

Electrospun Icariin-Loaded Core-Shell Collagen, Polycaprolactone, Hydroxyapatite Composite Scaffolds for the Repair of Rabbit Tibia Bone Defects

Background

Electrospinning is a widely used technology that can produce scaffolds with high porosity and surface area for bone regeneration. However, the small pore sizes in electrospun scaffolds constrain cell growth and tissue-ingrowth. In this study, novel drug-loading core-shell scaffolds were fabricated via electrospinning and freeze drying to facilitate the repair of tibia bone defects in rabbit models.

Materials and Methods

The collagen core scaffolds were freeze-dried containing icariin (ICA)-loaded chitosan microspheres. The shell scaffolds were electrospun using collagen, polycaprolactone and hydroxyapatite materials to form CPH composite scaffolds with the ones containing ICA microspheres named CPHI. The core-shell scaffolds were then cross-linked by genipin. The morphology, microstructure, physical and mechanical properties of the scaffolds were assessed. Rat marrow mesenchymal stem cells from the wistar rat were cultured with the scaffolds. The cell adhesion and proliferation were analysed. Adult rabbit models with tibial plateau defects were used to evaluate the performance of these scaffolds in repairing the bone defects over 4 to 12 weeks.

Results

The results reveal that the novel drug-loading core-shell scaffolds were successfully fabricated, which showed good physical and chemical properties and appropriate mechanical properties. Furthermore, excellent cells attachment was observed on the CPHI scaffolds. The results from radiography, micro-computed tomography, histological and immunohistochemical analysis demonstrated that abundant new bones were formed on the CPHI scaffolds.

Conclusion

These new core-shell composite scaffolds have great potential for bone tissue engineering applications and may lead to effective bone regeneration and repair.

Cockle Shell-Derived Calcium Carbonate (Aragonite) Nanoparticles: A Dynamite to Nanomedicine

Cockle shell is an external covering of small, salt water edible clams (Anadara granosa) that dwells in coastal area. This abundant biomaterial is hard, cheap and readily available with high content of calcium carbonate in aragonite polymorphic form. At present, cockle shell-derived calcium carbonate nanoparticles (CSCaCO3NPs) with dual applications has remarkably drawn significant attention of researchers in nanotechnology as a nanocarrier for delivery of different categories of drugs and as bone scaffold due to its beneficial potentials such as biocompatibility, osteoconductivity, pH sensitivity, slow biodegradation, hydrophilic nature and a wide safety margin. In addition, CSCaCO3NP possesses structural porosity, a large surface area and functional group endings for electrostatic ion bonds with high loading capacity. Thus, it maintains great potential in the drug delivery system and a large number of biomedical utilisations. The pioneering researchers adopted a non-hazardous top-down method for the synthesis of CSCaCO3NP with subsequent improvements that led to the better spherical diameter size obtained recently which is suitable for drug delivery. The method is therefore a simple, low cost and environmentally friendly, which involves little procedural steps without stringent temperature management and expensive hazardous chemicals or any carbonation methods. This paper presents a review on a few different types of nanoparticles with emphasis on the versatile most recent advancements and achievements on the synthesis and developments of CSCaCO3NP aragonite with its applications as a nanocarrier for drug delivery in nanomedicine.

In vivo evaluation of a novel nanocomposite porous 3D scaffold in a rabbit model: histological analysis

The healing of load-bearing segmental defects in long bones is a challenge due to the complex nature of the weight that affects the bone part and due to bending, shearing, axial, and torsional forces. An innovative porous 3D scaffolds implant of CaCO₃ aragonite nanocomposite derived from cockle shell was advanced for substitute bone solely for load-bearing cases. The biomechanical characteristics of such materials were designed to withstand cortical bone strength. In promoting bone growth to the implant material, an ideal surface permeability was formed by means of freeze drying and by adding copolymers to the materials. The properties of coating and copolymers supplement were also assessed for bone-implant connection resolutions. To examine the properties of the material in advanced biological system, an experimental trial in an animal model was carried out. Critical sized defect of bone was created in rabbit's radial bone to assess the material for a load-bearing application with a short and extended period assessment with histological evaluation of the incorporated implanted material to the bone of the host. Trials in animal models proved that the material has the capability of enduring load-bearing conditions for long-term use devoid of breaking or generating stress that affects the host bone. Histological examination further confirmed the improved integration of the implanted materials to the host bone with profound bone development into and also above the implanted scaffold, which was attained with negligible reaction of the tissues to a foreign implanted material.