Ultrasonic synthesis of hydroxyapatite in non-cavitation and cavitation modes

Study on the mechanism of ultrasonic cavitation effect on the surface properties enhancement of TC17 titanium alloy

In industrial production and scientific research, ultrasonic cavitation technology, with its outstanding physical and chemical processing capabilities, has been widely applied in fields such as material surface modification, chemical synthesis, and biotechnology, becoming a focal point of research and application. This article delves into the effects of different ultrasonic frequencies on cavitation outcomes through the combined use of numerical simulation, fluorescence analysis, and high-speed photography, specifically analyzing the quantitative improvement in the mechanical properties of TC17 titanium alloy under ultrasonic cavitation at frequencies of 20 kHz, 30 kHz, and 40 kHz. The study found that at an ultrasonic frequency of 20 kHz, the maximum expansion radius of cavitation bubbles can reach 51.4 μm, 8.6 times their initial radius. Correspondingly, fluorescence intensity and peak area also increased to 402.8 and 28104, significantly above the baseline level. Moreover, after modification by ultrasonic cavitation, the original machining marks on the surface of TC17 titanium alloy became fainter, with the emergence of new, uniformly distributed microfeatures. The microhardness of the material increased from 373.7 Hv to 383.84 Hv, 396.62 Hv, and 414.06 Hv, with a maximum improvement of 10.8 %. At the same time, surface height difference and roughness significantly decreased (to 3.168 μm and 0.61 μm respectively), with reductions reaching 45.1 % and 42.4 %, indicating a significant improvement in material surface quality. Notably, there is a negative correlation between the improvement of mechanical properties and ultrasonic frequency, suggesting that the improvement effects decrease as ultrasonic frequency increases. This research not only reveals the quantitative relationship between ultrasonic cavitation frequency and material surface modification effects but also provides a solid scientific basis and practical guidance for the application of ultrasonic cavitation technology in surface engineering, signifying the technology's potential for broad application in the future.

Sonoproduction of nanobiomaterials - A critical review

Ultrasound (US) demonstrates remarkable potential in synthesising nanomaterials, particularly nanobiomaterials targeted towards biomedical applications. This review briefly introduces existing top-down and bottom-up approaches for nanomaterials synthesis and their corresponding synthesis mechanisms, followed by the expounding of US-driven nanomaterials synthesis. Subsequently, the pros and cons of sono-nanotechnology and its advances in the synthesis of nanobiomaterials are drawn based on recent works. US-synthesised nanobiomaterials have improved properties and performance over conventional synthesis methods and most essentially eliminate the need for harsh and expensive chemicals. The sonoproduction of different classes and types of nanobiomaterials such as metal and superparamagnetic nanoparticles (NPs), lipid- and carbohydrate-based NPs, protein microspheres, microgels and other nanocomposites are broadly categorised based on the physical and/or chemical effects induced by US. This review ends on a good note and recognises US-driven synthesis as a pragmatic solution to satisfy the growing demand for nanobiomaterials, nonetheless some technical challenges are highlighted.

Calcium hydroxyapatite nanoparticles as a reinforcement filler in dental resin nanocomposite

The current study focuses on the fabrication of calcium hydroxyapatite (Ca₁₀(PO₄)₆(OH)₂) (HA) in a nanorange having whiskers- and cubic-shaped uniform particle morphology. The synthesized HA particles hold a promising feature as reinforcement fillers in dental acrylic resin composite. They increase the efficacy of reinforcement by length and aspect ratio, uniformity, and monodispersity. Therefore, the acrylic resin was reinforced with the as-synthesized monodispersed HA filler particles (0.2-1 Wt%). The presence of filler particles in the composite had a noticeable effect on the tribological and mechanical properties of the dental material. The morphological effect of HA particles on these properties was also investigated, revealing that cubic-shaped particles showed better results than whiskers. The as-fabricated composite (0.4 Wt%) of the cubic-shaped filler particles showed maximum hardness and improved antiwear/antifriction properties. Particle loading played its part in determining the optimum condition, whereas particle size also influenced the reinforcement efficiency. The current study revealed that particle morphology, particle size, uniformity, etc., of HA fillers, greatly influenced the tribological and mechanical properties of the acrylic resin-based nanocomposite. Improvement in the tribological properties of HA particle-reinforced acrylic resin composites (HA-acrylic resin) followed the trend as AR < C_mC < WC < CC.

Ultrasound-irradiated synthesis of 3-mercaptopropyl trimethoxysilane-modified hydroxyapatite derived from fish-scale residues followed by ultrasound-assisted organic dyes removal

We report a novel method for the synthesis of 3-mercaptopropyl trimethoxysilane-modified hydroxyapatite (FHAP-SH) derived from fish-scale residues by using ultrasound irradiation. Scanning electron microscopy, transmission electron microscopy, energy-dispersive spectroscopy, X-ray diffraction, and Fourier transform infrared spectroscopy were used for the FHAP-SH characterization. Then, the organic dye adsorption on the FHAP-SH was monitored through an ultrasound process. After the dye removal optimization, significant improvements were observed in the maximum adsorption capacities for Congo Red (CR, 500 mg g^-1), Coomassie Brilliant Blue G 250 (CB, 235 mg g^-1), and Malachite Green (MG, 625 mg g^-1). The adsorption behaviors of these dyes were fitted by using the Langmuir isotherm model with a high coefficient of determination values ranging from 0.9985 to 0.9969. The adsorption of the three dyes onto FHAP-SH was an endothermic process based on the adsorption thermodynamics model, while the adsorption kinetics analysis of the dyes presented a good alignment with the pseudo-second-order kinetics. The FHAP-SH exhibits a remarkably high adsorption capacity, is inexpensive, and fulfills the ecofriendly requirements of dye wastewater treatment, especially in the textile industry.

Effect of reaction condition on microstructure and properties of (NiCuZn)Fe2O4 nanoparticles synthesized via co-precipitation with ultrasonic irradiation

Nano-spinel ferrites synthesized via chemical co-precipitation method are small in size and have serious agglomeration phenomenon, which makes separation difficult in the subsequent process. Ni0.4Cu0.2Zn0.4Fe2O4 ferrites nanoparticles were synthesized via co-precipitation assisted with ultrasonic irradiation produced by ultrasonic cleaner with 20 kHz frequency using chlorinated salts and KOH as initial materials. The effects of ultrasonic power (0, 40 W, 60 W, 80 W) and reaction temperature on the microstructure and magnetic properties of ferrite nanoparticles were investigated. The structure analyses via XRD revealed the successful formation of pure (NiCuZn)Fe2O4 ferrites nanospinel without any impurity. The crystallites sizes were less than 40 nm and the lattice constant was near 8.39 Å. The TEM showed ferrite particle polygonal. M-H analyses performed the saturation magnetization and coercivity of ferrite nanoparticles obtained at the reaction temperature of 25℃ were higher than at 50℃ with same power. The samples exhibited the highest values of Ms 55.67 emu/g at 25℃ and 47.77 emu/g at 50℃ for 60 W and the lowest values of Hc 71.23 Oe at 25℃ for 40 W and 52.85 Oe at 50℃ for 60 W. The squareness ratio (SQR) were found to be lower than 0.5, which revealed the single magnetic domain nature (NiCuZn)Fe2O4 nanoparticles. All the outcomes show the ultrasonic irradiation has positive effects on improving the microstructure and increasing magnetic properties.

Multifunctional Hydroxyapatite/Silver Nanoparticles/Cotton Gauze for Antimicrobial and Biomedical Applications

Medical textiles have played an increasingly important protection role in the healthcare industry. This study was aimed at improving the conventional cotton gauze for achieving advanced biomedical specifications (coloration, UV-protection, anti-inflammation, and antimicrobial activities). These features were obtained by modifying the cotton gauze fabrics via in-situ precipitation of hydroxyapatite nanoparticles (HAp NP), followed by in-situ photosynthesis of silver (Ag) NPs with ginger oil as a green reductant with anti-inflammation properties. The HAp-Ag NPs coating provides good UV-protection properties. To further improve the HAp and Ag NPs dispersion and adhesion on the surface, the cotton gauze fabrics were modified by cationization with chitosan, or by partial carboxymethylation (anionic modification). The influence of the cationic and anionic modifications and HAp and Ag NPs deposition on the cotton gauze properties (coloration, UV-protection, antimicrobial activities, and water absorption) was thoroughly assessed. Overall, the results indicate that chemical (anionic and cationic) modification of the cotton gauze enhances HAp and Ag NPs deposition. Chitosan can increase biocompatibility and promotes wound healing properties of cotton gauze. Ag NP deposition onto cotton gauze fabrics brought high antimicrobial activities against Candida albicans, Gram-positive and Gram-negative bacteria, and improved UV protection.

Study on the effect of oxidation-ultrasound treatment on the electrochemical properties of activated carbon materials

Activated carbon (AC) has been widely used in water treatment because of its rich pore structure, large specific surface area, simple production process, low preparation cost and wide source of raw materials. In this paper, the regeneration efficiency of low-frequency ultrasonic pretreatment (40 kHz, 115Μw/cm³) on biological activated carbon (BAC) is investigated, and its principle is discussed. The results show that the micro-jet and micro-liquid flow with high temperature and pressure produced by micro-bubble rupture during ultrasonic cavitation play an important role in the regeneration of activated carbon. And optimum ultrasonic treatment time is determined (5 min). In addition, the preparation of cu-loaded activated carbon by ultrasound-microwave method is investigated to pretreat wastewater produced in paracetamol production. The results show that Cu and Cu oxides can be loaded on activated carbon surface by ultrasonic-microwave pretreatment. Finally, the pretreatments of activated carbon by physical, chemical and physical-chemical method are investigated. The effects of the above different pretreatment methods on the structure and adsorption properties of activated carbon are compared and evaluated.

Effect of Ultrasound Irradiation on the Synthesis of Hydroxyapatite/Titanium Oxide Nanocomposites

Bioceramic materials, such as hydroxyapatite, Ca10(PO4)6(OH)2, (HAp), can be chemically bound to bone tissue; since they are bioactive and biocompatible. HAp, titanium oxide (TiO2), and hydroxyapatite/titanium oxide (HAp/TiO2) nanocomposite nanoparticles were obtained by ultrasound irradiation assisted by sol-gel and co-precipitation methods at different time intervals, using Ca(NO3)2•4H2O, (NH4)2HPO4, and TiOSO4•xH2O as calcium, phosphorus, and titanium sources, respectively. HAp, TiO2, and HAp/TiO2 nanocomposite powders were characterized by X-ray Diffraction (XRD) and Raman Spectroscopy. The percentages of anatase phase for TiO2 and of monoclinic and hexagonal phases for HAp were quantified by Rietveld refinement. Furthermore, sample crystallinity in each material was enhanced by increasing the ultrasound irradiation time. The nanoparticle shape was semi-spherical, agglomerated, and between 17 and 20 nm in size. The agglomeration of particles in the samples was corroborated with a Field Emission Scanning Electron Microscope (FESEM).

Synthesis of Graphene Nanoribbons–Hydroxyapatite Nanocomposite Applicable in Biomedicine and Theranostics

In order to investigate the effect of graphene nanoribbons on the final properties of hydroxyapatite-based nanocomposites, a solvothermal method was used at 180 °C and 5 h for the synthesis of graphene nanoribbons–hydroxyapatite nanopowders by employing hydrogen gas injection. Calcium nitrate tetrahydrate and diammonium hydrogenphosphate were used as calcium and phosphate precursors, respectively. To synthesize the powders, a solvent containing diethylene glycol, anhydrous ethanol, dimethylformamide, and water was used. Graphene oxide nanoribbons were synthesized by chemical unzipping of carbon nanotubes under oxidative conditions. The synthesized powders were consolidated by spark plasma sintering methodat 950 °C and a pressure of 50 MPa. The powders and sintered samples were then evaluated using X-ray diffraction, Raman spectroscopy, high-resolution transmission electron microscopy, Vickers microindentation techniques, and biocompatibility assay. The findings of this study showed that the final powders synthesized by the solvothermal method had calcium to phosphate ratio of about 1.67. By adding a small amount of graphene nanoribbon (0.5%W), elastic modulus and hardness of hydroxyapatite increased dramatically. In biological experiments, the difference of hydroxyapatite effect in comparison with the nanocomposite was not significant. The findings of this study showed that graphene nanoribbons have a positive effect on the properties of hydroxyapatite, and these findings would be useful for the medical and theranostic application of this type of nanocomposites.

Ultrasonic aqueous synthesis of corrosion resistant hydroxyapatite coating on magnesium alloys for the application of long-term implant

For the orthopedic application, the promising biodegradable magnesium alloys gained increasing attention. In order to improve the interface bonding strength and corrosion resistance of magnesium alloys, a novel ultrasonic aqueous synthesis approach was performed to produce hydroxyapatite coating on biodegradable magnesium alloys. The effect of ultrasonic time on the composition, microstructure, interface bonding strength and corrosion resistance of HA coated magnesium alloys were investigated. A dense and crack-free HA coating was synthesized by only ultrasonic cavitation for 1 h in the aqueous solution containing Ca²⁺ and PO₄^3- ions and the coating was constituted of bamboo leaf-like HA staggered irregularly, which endowed magnesium alloy with a sufficient interface bonding strength of 18.1 ± 2.2 MPa. The electrochemical performance and mineralization ability of the coated magnesium alloys were carried out in the simulated body fluids. Compared with bare magnesium samples, the coated samples presented excellent corrosion resistance and could rapidly induce apatite formation after only three days of immersion in the simulated body fluid (SBF). Moreover, in the immersion test of 90 days, HA coatings could provide a long-term protection for magnesium alloy substrate, indicating that ultrasonic aqueous synthesized HA coating could be acted as a promising modified biomaterial on magnesium alloys for the orthopedic application.

Photoluminescent Hydroxylapatite: Eu3+ Doping Effect on Biological Behaviour

Luminescent europium-doped hydroxylapatite (Eu_XHAp) nanomaterials were successfully obtained by co-precipitation method at low temperature. The morphological, structural and optical properties were investigated by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier Transform Infrared (FT-IR), UV-Vis and photoluminescence (PL) spectroscopy. The cytotoxicity and biocompatibility of Eu_XHAp were also evaluated using MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide)) assay, oxidative stress assessment and fluorescent microscopy. The results reveal that the Eu³⁺ has successfully doped the hexagonal lattice of hydroxylapatite. By enhancing the optical features, these Eu_XHAp materials demonstrated superior efficiency to become fluorescent labelling materials for bioimaging applications.

Ultrasound Assisted Green Synthesis of Silver and Iron Oxide Nanoparticles Using Fenugreek Seed Extract and Their Enhanced Antibacterial and Antioxidant Activities

This study reports a facile and ecofriendly approach for the ultrasound assisted synthesis of silver and iron oxide nanoparticles and their enhanced antibacterial and antioxidant activities. The fenugreek seed extract was used as reducing, capping, and stabilizing agent in the synthesis of nanoparticles. The transmission electron microscopy results showed that nanoparticles synthesized by ultrasonication have a smaller size (~20 nm) as compared to the nanoparticles fabricated by magnetic stirring (~40 nm). The color change of the solution from milky white to brown suggested the formation of silver nanoparticles which was confirmed by the presence of an absorbance peak at 396 nm. The results of powder X-ray diffraction and energy dispersive X-ray spectroscopy confirmed the crystallinity and elements present in nanoparticles synthesized using fenugreek seed extract. Fourier transform infrared analysis showed that the fenugreek seed phytochemicals were coated on the nanoparticle surface. Thermal gravimetric analysis showed the thermal degradation and stability of nanoparticles. Magnetization study of iron oxide nanoparticles confirmed the superparamagnetic nature. The silver nanoparticles showed antibacterial activities against both gram-negative (Escherichia coli) and gram-positive (Staphylococcus aureus) bacteria, while no antibacterial activities were observed for iron oxide nanoparticles. The ultrasound assisted nanoparticles showed higher stability and antibacterial and antioxidant activity compared with the nanoparticles fabricated by magnetic stirring.

Mechanism of ultrasonic impregnation on porosity of activated carbons in non-cavitation and cavitation regimes

Ultrasonic impregnation has proven to be an effective method to improve surface area and pore volume during preparation of activated carbons. However, the mechanism by which the promotion effect of ultrasonic impregnation is still ambiguous. Fundamental wave pressure (FWP) and broadband integrated pressure (BIP) were used to estimate the non-cavitation (vibration) energy and cavitation energy, respectively. The effects of FWP and BIP on the pore volume, surface area, surface functional groups, and microcosmic morphology were investigated in non-cavitation and cavitation regimes. Ultrasonic vibration promoted the surface enlargement and pore development of activated carbons, and it mainly affected the development of mesopore volume (V_mes) in both the pore volume and the mesopore-size-distribution range. The V_mes was enhanced by 60%-100% in the non-cavitation regime. Ultrasonic cavitation also facilitated porosity development of activated carbons, and it mainly affected the development of specific surface area (S_BET) and micropore volume (V_mic). The excessive cavitation led to a decrease of the porosity of activated carbons, so the BIP should be optimized during impregnation. The highest S_BET, V_mic, and V_mes for activated carbons were obtained by in the presence of both FWP and BIP, which were enhanced by 29.05%, 30.23%, and 113.33%, respectively, compared with the corresponding value for the activated carbon prepared without using ultrasonic impregnation. This work provided new insight into the role of the acoustic energy present during impregnation in tuning properties of activated carbons.

S. N. SN, Sagadevan S, Hoque ME, Kulandaivelu R. Advanced lithium substituted hydroxyapatite nanoparticles for antimicrobial and hemolytic studies

In this study, pure hydroxyapatite (HAP) and lithium substituted hydroxyapatite (Li-HAP) nanoparticles were synthesized by a sonochemical synthesis process and investigated for their antimicrobial and hemolytic activities.

Investigations on sonofragmentation of hydroxyapatite crystals as a function of strontium incorporation

Hydroxyapatite (Ca₁₀(PO₄)₆(OH)₂, HA) is chemically similar to the mineral component of bones and hard tissues in mammals. Various cations can substitute calcium in the crystal structure of hydroxyapatite. Among them strontium triggers interest, because strontium incorporated hydroxyapatite increases the number of bone forming sites in addition to having good biocompatibility. In the present investigation strontium substituted hydroxyapatite (SHA) in the compositions range 0, 10, 20, 50 and 100 mol% have been synthesized by precipitation method and subjected to ultrasonic treatment for different time intervals to gain insight on the role of ultrasound in modifying the morphology of SHA. This study reveals that the aspect ratio of SHA varied with the duration of ultrasonication. SHA samples subjected to 5 min ultrasound experienced an increase in aspect ratio. Further increase of ultrasonication time tends to decrease the aspect ratio invariably for all SHA samples indicating particle fragmentation. The extent of sonofragmentation as a function of percentage incorporation of strontium in HA lattice has been studied as a part of the present investigation. This study indicated that strain in the HA lattice has correlation with strontium incorporation, leading to varied extent of sonofragmentation. Also, the investigation suggested that 100% substitution of calcium sites by strontium leads to a relatively lesser strain and hence poor fragmentation. To the best of our knowledge the report on sonofragmentation of HA crystallites as a function of strontium incorporation is first of its kind in the literature.

Application of hydroxyapatite and its modified forms as adsorbents for water defluoridation: an insight into process synthesis

Fluorosis is a major scourge in many countries caused by prolonged consumption of drinking water with high fluoride content found in groundwater resources. Hydroxyapatite (Hap) and its composite forms are excellent biomaterials that recently gained attention as efficient adsorbents, owing to its physical and chemical nature as it can substitute both cationic and anionic complexes present in an aqueous solution in its atomic arrangement. Its biological nature, biocompatibility and biodegradability along with its chemical characteristics such as crystallinity, stability, ion adsorption capability and highly specific catalytic activity make it suitable for a variety of applications especially in water treatment for fluoride removal. This review describes various techniques for synthesis of a wide variety of biogenic, synthetic, composite and modified forms of Hap for application in water defluoridation. Hap derived from natural sources or synthesized using conventional methods, hydrothermal, sol-gel or advanced sonication-cum-precipitation technique varied in terms of its crystallinity, structure, size, etc., which affect the fluoride removal capacity. The advantage and disadvantages of various synthesis methods, process parameters and product characteristics have been compiled, which may help to identify a suitable synthesis method for a desired Hap product for potential application and future perspectives in water treatment.