Pure Calcium Phosphate Research Articles

PD50-10 EVALUATING THE ENCRUSTATION FEATURES DUE TO THE SHORT-TERM URETERAL STENT PLACEMENT USING MICRO-COMPUTED TOMOGRAPHY: THE RESULTS FROM A PROSPECTIVE STUDY

You have accessJournal of UrologyCME1 May 2022PD50-10 EVALUATING THE ENCRUSTATION FEATURES DUE TO THE SHORT-TERM URETERAL STENT PLACEMENT USING MICRO-COMPUTED TOMOGRAPHY: THE RESULTS FROM A PROSPECTIVE STUDY Shinji Fukui, Takashi Yoshida, Kuniko Takemoto, and Hidefumi Kinoshita Shinji FukuiShinji Fukui More articles by this author , Takashi YoshidaTakashi Yoshida More articles by this author , Kuniko TakemotoKuniko Takemoto More articles by this author , and Hidefumi KinoshitaHidefumi Kinoshita More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000002621.10AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: To evaluate the short-term encrustation formation and encrustation volume of the ureteral stent, focusing on the major stone components (i.e., calcium oxalate and calcium phosphate). METHODS: Eighty-four patients requiring ureteral stent placement after retrograde intrarenal surgery (RIRS) were enrolled. After stent removal on postoperative day 14, the encrustation volume on the stent surface was measured by micro-computed tomography. Of the 84 patients, 71 were eligible for this study, excluding seven patients with no encrustation, two patients with uric acid (1 patient) and cystine (1 patient), and four patients with no available data. The encrustation volume was evaluated by micro-CT, and the stone components and the component ratio were determined using infrared spectroscopy. RESULTS: All included patients had encrustation in the inner lumen of the stent. Compared to this, encrustation on the outer surface was observed only in 3 (4.2%) patients (p <0.001). Sixty-seven patients (94%) had calcium oxalate as the primary stone component, 42 (62%) of whom had pure calcium oxalate. Four patients (6%) had pure calcium phosphate as the primary stone component, three of whom had mixed stone with calcium phosphate. Cases with calcium oxalate showed a higher prevalence of stone components than those with calcium phosphate (p <0.001). However, cases with calcium phosphate stone had a significantly greater median inner encrustation volume compared to those with calcium oxalate stone (3.66 mm3 vs. 1.11 mm3; p <0.001). There was no difference observed in the encrustation volume on the outer surface between the two stone components (p=0.86). In multivariate analysis, crystalluria (p=0.013) and primary calcium phosphate component (p <0.001) were significantly associated with the increased total encrustation volume on the stent. CONCLUSIONS: This study revealed that the encrustation volume on the stent was significantly greater for calcium phosphate compared to calcium oxalate with the short-term indwelling ureteral stent. Thus, early stent removal may be recommended for patients with calcium phosphate stones. Source of Funding: No source of funding © 2022 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 207Issue Supplement 5May 2022Page: e840 Advertisement Copyright & Permissions© 2022 by American Urological Association Education and Research, Inc.MetricsAuthor Information Shinji Fukui More articles by this author Takashi Yoshida More articles by this author Kuniko Takemoto More articles by this author Hidefumi Kinoshita More articles by this author Expand All Advertisement PDF DownloadLoading ...

Urinary Metabolic Disturbances During Topiramate Use and their Reversibility Following Drug Cessation

ObjectiveTo understand the metabolic disturbances of stone formers currently taking topiramate and to examine the reversibility of these disturbances with cessation of the medication. Materials and MethodsAll progress notes written by 5 endourologists from a single academic center were retrospectively reviewed from January 2010 to July 2020 containing the words “topiramate” or “topamax.” Inclusion criteria were age >18 and presence of either a 24-hour urine sample or stone analysis while on topiramate. In addition, a subgroup of 18 patients with 24-hour urine samples before and after stopping topiramate were identified. ResultsA total of 93 patients were identified and included for final analysis. Twenty-four hour urine samples were available in 67 patients and showed mean citrate excretion of 331 ± 322 mg/d, mean pH of 6.6 ± 0.5, and mean calcium phosphate supersaturation of 1.9 ± 1.1. In the subgroup analysis urinary citrate excretion increased from 225 mg/d to 614 mg/d (P <.01) and pH decreased from 6.59 ± 0.54 to 6.33 ± 0.47 (P = .06) after stopping topiramate. In addition, 114 stone events occurred in 73 distinct patients, with 50% of stones either pure or majority (≥50%) calcium phosphate by composition. ConclusionHypocitraturia and elevated pH is seen during topiramate use with resultant higher rate of calcium phosphate stone formation compared to the general population. Stopping topiramate leads to significant increase in citrate excretion and normalization of pH. These metabolic disturbances appear to be reversible with medication cessation.

Detection of calcium phosphate species in soil by confocal μ‐Raman spectroscopy#

AbstractBackgroundRaman spectroscopy is a promising but largely underexplored tool for the detection of phosphates (P) in soil. Although it requires minimal sample preparation, it has been demonstrated mainly in test matrices or substrates to circumvent the typical signal interference caused by fluorescence of organic matter in actual agricultural soils.AimsThe aim of this study was to highlight the Raman spectroscopic detection and identification of distinct calcium phosphate species amended in contrasting soil matrices—including a real arable soil.MethodsPure calcium dihydrogen phosphate [Ca(H2PO4)2·H2O], calcium hydrogen phosphate (CaHPO4), and β‐tricalcium phosphate [β‐Ca3(PO4)2] were each amended in Luvos® healing earth, loess from a C‐horizon, and a loam arable soil from an Ap‐horizon at a dose of 1 mmol (10 g soil)–1. The unique Raman signature of each pure calcium phosphate species was determined by confocal μ‐Raman spectroscopy and used subsequently as a reference spectrum to identify the compound in each soil matrix. Controls without added P were also analyzed.ResultsCa(H2PO4)2·H2O, CaHPO4, and β‐Ca3(PO4)2 were each unambiguously detected in the treated soils. Native hydroxyapatite [Ca5(PO4)3(OH)], quartz (SiO2), feldspar (NaAlSi3O8), calcite (CaCO3), and dolomite [CaMg(CO3)2] were also identified, for example, in the Raman microscopic image of the control Luvos® healing earth sample. Intrinsic β‐Ca3(PO4)2 and Ca5(PO4)3(OH) present in Ap‐horizon loam were detected and distinguished from each other by a Lorentzian fitting, which deconvoluted the individual Raman signals from an unresolved peak.ConclusionsThe usefulness of confocal μ‐Raman spectroscopy to detect distinct P species present in agricultural soil could be shown as a proof of concept.

Flow-driven synthesis of calcium phosphate-calcium alginate hybrid chemical gardens.

Systems far-from-equilibrium self-assemble into spatiotemporal structures. Here, we report on the formation of calcium alginate gardens along with their inorganic hybrids when a sodium alginate solution containing sodium phosphate in various compositions is injected into a calcium chloride reservoir. The viscoelastic properties of the membranes developed are controlled by the injection rate, while their thickness by the amount of sodium phosphate besides diffusion. Inorganic hybrid membranes with constant thickness are synthesized in the presence of a sufficient amount of sodium phosphate. The electrochemical characterization of the membranes suggests that the driving force is the pH-gradient developing along the two sides; hence, the cell potential can be controlled by the addition of alkaline sodium phosphate into the sodium alginate solution.

Enteric Coated Oral Delivery of Hydroxyapatite Nanoparticle for Modified Release Vitamin D3 Formulation

Vitamin D3 (VD) and calcium phosphate play a vital role in bone homeostasis. Factors such as obesity or gastrointestinal problems can render the use of pure VD and calcium phosphate supplements ineffective. This study investigated the possibility of using VD-loaded hydroxyapatite nanoparticles for the codelivery of VD and Ca3(PO4)2. Due to the high affinity of Ca3(PO4)2 for bone tissue, HA is an ideal delivery system to deliver VD to target tissue. Herein, HA nanoparticles were synthesized and loaded with VD using a vacuum evaporation method. The synthesized HA-VD nanoparticles were morphologically and chemically characterized by SEM, FTIR, and TGA. The system exhibited a two-stage release pattern, which includes a first-day burst release (35%) and sustained release for a further ten days. The cytocompatibility and cell penetrative ability of the nanoparticle system were assessed in vitro using preosteoblast cells: the system is nontoxic and well-tolerated. Finally, the VD-loaded HA nanoparticles were coated with a gastroresistant polymer, hypromellose phtalate-55 (HP-55) in order to protect the pH-sensitive HA from degradation at lower pHs. A coaxial electrospray technique was employed to achieve this. In all, the tested HA-VD system is a viable alternative for codelivery of VD, Ca2+, and PO43- to their target tissues.

Mechanical properties and biomedical application characteristics of degradable polylactic acid–Mg–Ca3(PO4)2 three-phase composite

Polylactic acid (PLA), pure magnesium powder, and calcium phosphate powder were used to form a three-phase degradable biomedical composite. The effects of various powder proportions in polylactic acid–Mg–Ca3(PO4)2 composites were analyzed through mechanical and biological tests, which revealed that both the tensile and impact strength of the composite increased. Additionally, ductility presented only after a small proportion of powder was added. Hardness slightly increased because of dispersion strengthening. Furthermore, the addition of pure magnesium and calcium phosphate accelerated the degradation rate, and biocompatible salts were generated after degradation, which can improve healing and renewal in bone tissue. None of the composites exhibited cytotoxicity, meeting biological safety requirements. Overall, PLA10M10C (10 wt.% Mg, 10 wt.% Ca3(PO4)2) exhibited superior performance. Accordingly, PLA10M10C can serve as a reference for degradable biomedical material applications in orthopedic implants.

Mechanically Stable β-TCP Structural Hybrid Scaffolds for Potential Bone Replacement

The authors report on the manufacturing of mechanically stable β-tricalcium phosphate (β-TCP) structural hybrid scaffolds via the combination of additive manufacturing (CerAM VPP) and Freeze Foaming for engineering a potential bone replacement. In the first step, load bearing support structures were designed via FE simulation and 3D printed by CerAM VPP. In the second step, structures were foamed-in with a porous and degradable calcium phosphate (CaP) ceramic that mimics porous spongiosa. For this purpose, Fraunhofer IKTS used a process known as Freeze Foaming, which allows the foaming of any powdery material and the foaming-in into near-net-shape structures. Using a joint heat treatment, both structural components fused to form a structural hybrid. This bone construct had a 25-fold increased compressive strength compared to the pure CaP Freeze Foam and excellent biocompatibility with human osteoblastic MG-63 cells when compared to a bone grafting Curasan material for benchmark.

Growth and Spectral Investigation on Pure Calcium Phosphate Doped With (Copper and Magnesium) Crystals

Calcium stones are most commonly occurring form of cholelithiasis or gallbladder stones most one of the oldest and common afflictions of humans. Calcium phosphate is dissolved minerals in causes of renal to gallbladder stone in both human and animals. Of course, the calcium phosphate is one of the components of gallbladder. Calcium phosphate doped with (Cu and Mg) are crystals are grown by sol-gel method. In the present work the growth and characterization of pure and doped with (Cu and Mg) crystals. The grown crystals were characterization by FT-IR, SEM-EDX and TG/DTA analysis.

The study of morphological evolution, biocorrosion resistance, and bioactivity of pulse electrochemically deposited Hydroxyapatite/ZnO composite on NiTi superelastic alloy

In this work, the effect of zinc oxide nanoparticles on hydroxyapatite deposited on NiTi superelastic alloy was studied. Various concentrations of nanoparticles (200, 400, and 800 mg/L) along with cetrimonium bromide (100 mg/L) as a dispersant agent were added to the coating electrolyte. Morphological observations showed that zinc oxide encouraged hydroxyapatite plate-like crystals to grow in longitudinal and transverse directions, turning into a bone-like structure with greater pores. XRD and FTIR indicated the favorable impact of zinc oxide on the synthesis of pure hydroxyapatite as the most stable calcium phosphate phase. Next, the corrosion evaluations revealed that zinc oxide successfully reduced the corrosion current density of composite coatings down to 1.35 nA/cm2, where pure calcium phosphate coating exhibited 19.05 nA/cm2. Topographic evaluations (AFM) proved a consistent rise in roughness parameters where the roughness average climbed from 208.3 nm for calcium phosphate coating up to 436.45 nm for the composite coating with the highest ZnO concentration. The adhesion strength of composite coatings was above 15 MPa (the critical requirement for orthopedic applications), despite calcium phosphate coating. The wettability results also differed dramatically where calcium phosphate coating exhibited 31.17°, but it dropped to 12.62° for the composite coating formed in the solution containing 400 mg/L ZnO nanoparticles. Ultimately, bioactivity analysis in simulated body fluid revealed that ZnO nanoparticles not only promoted growth but also restricted the size distribution of cauliflower-like apatite grains.

MP54-13 METABOLIC DISTURBANCES DURING TOPIRAMATE USE AND THEIR REVERSIBILITY FOLLOWING DRUG CESSATION

You have accessJournal of UrologyStone Disease: Epidemiology & Evaluation II (MP54)1 Sep 2021MP54-13 METABOLIC DISTURBANCES DURING TOPIRAMATE USE AND THEIR REVERSIBILITY FOLLOWING DRUG CESSATION Daniel Pelzman, Eman Kazi, and Michelle Semins Daniel PelzmanDaniel Pelzman More articles by this author , Eman KaziEman Kazi More articles by this author , and Michelle SeminsMichelle Semins More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000002084.13AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: Topiramate is a commonly used medication which inhibits carbonic anhydrase, causing renal tubular acidosis and hypocitraturia, thereby increasing the risk for kidney stone formation. Despite the strong association between topiramate use and kidney stone formation, few studies have examined the characteristics of stone formers taking topiramate. Additionally, the reversibility of the metabolic disturbances with cessation of the medication has not been previously studied. To fill this knowledge gap, we investigated the stone composition and 24-hour urine samples of a large cohort of stone formers taking topiramate. METHODS: All progress notes written by 5 endourologists from a single academic center were retrospectively reviewed from January 2010 to July 2020 containing the words “topiramate” or “topamax.” Inclusion criteria were age >18 and presence of either a 24-hour urine sample or stone analysis while on topiramate. In addition, a subgroup of 17 patients with 24-hour urine samples before and after stopping topiramate were identified. RESULTS: A total of 93 patients were identified and included for final analysis. Twenty-four hour urine samples were available in 65 patients and showed mean citrate excretion of 333 mg/day (95% confidence interval (CI) [254-412]), mean pH of 6.54 (95% CI [6.41-6.68]), and mean calcium phosphate supersaturation of 1.8 (95% CI [1.6-2.1]). In the subgroup analysis, mean urinary citrate excretion increased from 233 mg/day (95% CI [135-330]) to 633 mg/day (95% CI [471-796], p<0.01), and pH decreased from 6.61 (95% CI [6.34-6.89]) to 6.34 (95% CI [6.12-6.56], p=0.06) after stopping topiramate (Figure 1). 114 stone events occurred in 73 distinct patients with 50% either pure or majority (≥50%) calcium phosphate by composition. CONCLUSIONS: Hypocitraturia and elevated pH is seen during topiramate use with resultant higher rate of calcium phosphate stone formation compared to the general population. Stopping topiramate leads to significant increase in citrate excretion and normalization of pH. Patients and providers should be aware of this risk when starting topiramate therapy. These metabolic disturbances appear to be reversible with medication cessation. Source of Funding: None © 2021 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 206Issue Supplement 3September 2021Page: e954-e954 Advertisement Copyright & Permissions© 2021 by American Urological Association Education and Research, Inc.MetricsAuthor Information Daniel Pelzman More articles by this author Eman Kazi More articles by this author Michelle Semins More articles by this author Expand All Advertisement Loading ...

Effect of aspartic acid on the crystallization kinetics of ACP and dentin remineralization

Type I collagen and non-collagen proteins are the main organic components of dentin. This study aimed to investigate the biomimetic remineralization of demineralized dentin by aspartic acid (Asp), which is abundant in non-collagenous proteins (NCPs). Asp was added to a mineralizing solution containing polyacrylic acid (PAA) to explore the mechanism of Asp regulating the pure amorphous calcium phosphate (ACP) phase transition process. The remineralization process and superstructure of the remineralized layer of demineralized dentin were evaluated and analyzed by transmission electron microscope (TEM) and scanning electron microscope (SEM), and the biological stability of the remineralized layer was investigated by collagenase degradation experiment. It demonstrated that Asp promoted the crystallization kinetics of PAA-stabilized amorphous calcium phosphate to hydroxyapatite (HAP), and shortened the remineralization time of demineralized dentin from 7 days to 2 days. The newly formed remineralized dentin had similar morphology and biological stability to the natural dentin layer. The presence of a large number of Asp residues in NCPs promoted the phase transformation of ACP, and further revealed the mechanism of action of NCPs in dentin biomineralization. This experiment also showed that Asp promoted the biomimetic remineralization of dentin; the morphology and hierarchical structure of remineralized layer was similar to that of natural teeth, and had good biological properties.

Physical and Mechanical Characterization of Crystalline Pure β-Tri Calcium Phosphate & Its Dopants as Bone Substitutes

β-Tri calcium phosphate ceramics play a significant role in several biomedical application for their marked resorbability and bioactivity. One of them is in bone grafting, where it is used for treating bone defects caused by wounds or osteoporosis. In the present work an in-depth and systematic study of pure and different doped variants (Zinc, Magnesium and Titanium) of β-Tri calcium phosphate was done. We have prepared pure β-Tri calcium phosphate and its different dopants of different strength. All together seven different composition were studied. We have tried to investigate some important features which are the prerequisite for their application. These include lattice parameter study, mechanical properties, contacts behaviour with SBF, haemolytic characteristics, and its cytotoxic nature. The capability of new apatite development on the surface of pure and doped β-TCP samples were also considered and compared by using Simulated Body Fluid (SBF) to observe their interaction with human body fluid.

Feasible and pure P2O5-CaO nanoglasses: An in-depth NMR study of synthesis for the modulation of the bioactive ion release

The use of bioactive glasses (e.g. silicates, phosphates, borates) has demonstrated to be an effective therapy for the restoration of bone fractures, wound healing and vascularization. Their partial dissolution towards the surrounding tissue has shown to trigger positive bioactive responses, without the necessity of using growth factors or cell therapy, which reduces money-costs, side effects and increases their translation to the clinics. However, bioactive glasses often need from stabilizers (e.g. SiO44−, Ti4+, Co2+, etc.) that are not highly abundant in the body and which metabolization is not fully understood. In this study, we were focused on synthesizing pure calcium phosphate glasses without the presence of such stabilizers. We combined a mixture of ethylphosphate and calcium 2-methoxyethoxide to synthesize nanoparticles with different compositions and degradability. Synthesis was followed by an in-depth nuclear magnetic resonance characterization, complemented with other techniques that helped us to correlate the chemical structure of the glasses with their physiochemical properties and reaction mechanism. After synthesis, the organically modified xerogel (i.e. calcium monoethylphosphate) was treated at 200 or 350 °C and its solubility was maintained and controlled due to the elimination of organics, increase of phosphate-calcium interactions and phosphate polycondensation. To the best of our knowledge, we are reporting the first sol-gel synthesis of binary (P2O5-CaO) calcium phosphate glass nanoparticles in terms of continuous polycondensated phosphate chains structure without the addition of extra ions. The main goal is to straightforward the synthesis, to get a safer metabolization and to modulate the bioactive ion release. Additionally, we shed light on the chemical structure, reaction mechanism and properties of calcium phosphate glasses with high calcium contents, which nowadays are poorly understood. Statement of SignificanceThe use of bioactive inorganic materials (i.e. bioactive ceramics, glass-ceramics and glasses) for biomedical applications is attractive due to their good integration with the host tissue without the necessity of adding exogenous cells or growth factors. In particular, degradable calcium phosphate glasses are completely resorbable, avoiding the retention in the body of the highly stable silica network of silicate glasses, and inducing a more controllable degradability than bioactive ceramics. However, most calcium phosphate glasses include the presence of stabilizers (e.g. Ti4+, Na+, Co2+), which metabolization is not fully understood and complicates their synthesis. The development of binary calcium phosphate glasses with controlled degradability reduces these limitations, offering a simple and completely metabolizable material with higher transfer to the clinics.

EFFECT OF SEED EXTRACTS OF Elettaria cardamomum ON CALCIUM OXALATE CRYSTALLIZATION

Kidney stone has tormented humans since the earliest records of civilization. Urinary stones are one of the oldest and the most common afflictions in humans. Calcium containing stones are the most common comprising about 75% of all urinary calculi, which may be in the form of pure calcium oxalate (50%) or calcium phosphate (5%) or a mixture of both (45 %). 10% of men and 3 % of women have a stone during their adult lives. A number of plants have been mentioned in the Indian ayurvedic system, which can prevent formation or dissolve kidney stones. In the present study, the inhibitory potency of different extracts of seeds of Elettaria cardamomum were evaluated on various stages of formation and on the growth of calcium oxalate crystals in vitro. A result obtained showed that alcoholic and aqueous extract has the higher capacity to inhibit the crystal formation and aggregation as compared to ethyl acetate and petroleum ether extracts.

Tough and Elastic α-Tricalcium Phosphate Cement Composites with Degradable PEG-Based Cross-Linker.

Dual setting cements composed of an in situ forming hydrogel and a reactive mineral phase combine high compressive strength of the cement with sufficient ductility and bending strength of the polymeric network. Previous studies were focused on the modification with non-degradable hydrogels based on 2-hydroxyethyl methacrylate (HEMA). Here, we describe the synthesis of suitable triblock degradable poly(ethylene glycol)-poly(lactide) (PEG-PLLA) cross-linker to improve the resorption capacity of such composites. A study with four different formulations was established. As reference, pure hydroxyapatite (HA) cements and composites with 40 wt% HEMA in the liquid cement phase were produced. Furthermore, HEMA was modified with 10 wt% of PEG-PLLA cross-linker or a test series containing only 25% cross-linker was chosen for composites with a fully degradable polymeric phase. Hence, we developed suitable systems with increased elasticity and 5–6 times higher toughness values in comparison to pure inorganic cement matrix. Furthermore, conversion rate from α-tricalcium phosphate (α-TCP) to HA was still about 90% for all composite formulations, whereas crystal size decreased. Based on this material development and advancement for a dual setting system, we managed to overcome the drawback of brittleness for pure calcium phosphate cements.

Effect of positioning on ureteric stone retropulsion: ‘gravity works’

To evaluate the potential impact of alterations in 'patient' position on laser-induced ureteric stone retropulsion in an in vitro model. A ceramic (phantom) stone was placed in a water-filled clear polymer tube and subjected to continuous laser energy until the stone had retropulsed a distance of 10 cm. The trial was stopped after 60 s if the stone had not reached 10 cm. The time and total energy needed to cause 10 cm of retropulsion were recorded at incline angles of 0°, 10°, 20°, and 40°; 10 trials at each angle were completed. The study was then repeated with pure calcium phosphate brushite stones. Retropulsion decreased with increasing incline angle of the saline-filled clear polymer tube. At 0° of incline the phantom stone reached a distance of 10 cm after 7.4 s. At 10°, 20° and 40°, the phantom stone migrated a mean maximum distance of 3.1, 1.2 and 0.7 cm, respectively, and the trial was stopped after 60 s. For the calcium phosphate stone, at 0° and 10° of incline, the stone reached 10 cm after 6.9 and 42.8 s, respectively (P < 0.05). At 20° and 40°, the calcium phosphate stone moved a mean maximum distance of 2.4 and 1 cm, and the trial was stopped after 60 s. Alterations in the angle of inclination reduced stone retropulsion during ureteroscopic lithotripsy in an in vitro model to <1 cm. Increasing the incline angle of a patient may effectively preclude retropulsion when performing laser lithotripsy of ureteric stones.

Corrosion and biocompatibility examination of multi-element modified calcium phosphate bioceramic layers

Multi-ions doped bioactive calcium phosphate (dCaP) layers were developed by pulse current deposition onto surgical grade titanium alloy material (Ti6Al4V). The coatings were electrodeposited from base electrolyte containing adequate amounts of calcium nitrate and ammonium dihydrogen phosphate at 70 °C. After electrodeposition, the pure CaP layers were doped with different ions that possess bioactive and antimicrobial properties, such as Zn2+, Mg2+, Sr2+ and Ag+ ions. The morphology and structure of coatings were characterized by Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Energy-dispersive X-ray Spectroscopy (EDX) as well as XRD and FT-IR measurements. The results revealed the pulse current deposited and surface post-treated CaP layer to be mainly in hydroxyapatite phase. The corrosion properties of bioceramic coatings were assessed in conventional simulated body fluid (SBF) in a three electrode open cell by using potentiodynamic polarization measurements over two weeks period. The electrochemical results revealed that the pure calcium phosphate (CaP) coated implant material and the bare implant possess the highest resistivity to corrosion, while the modified calcium phosphate coating showed lower corrosion resistance by at least one order of magnitude. The cell viability measurements showed that the electrochemically deposited CaP layer was biocompatible.

Study on the Structure and Properties of Crystalline Pure and Doped β-Tri Calcium Phosphate Ceramics

Resorbable Calcium Phosphate based bio-ceramics find wide application in arthroplasty. It requires better in-vivo mechanical strength and stability to effectively exploit the resorption behaviour. Present study reports synthesis and thorough characterization of undoped β-TCP along with Magnesium and Titanium doped (3wt% and 5 wt.%) β-TCP. Density, porosity, grain size and shape, percentage shrinkage and particle size distribution were measured. XRD and FTIR were done to examine the changes in crystalline phases and functional groups of all these ceramics. Scanning electron microscopy (SEM) was used to study the interconnectivity of pores, pore shape and size. Finally hemolysis study was done to understand the degree of hemocompatibility. Primary results suggest that all the samples retained β-TCP phase, structures were submicron grained with uniform, nodular grains and good amount of porosity. All specimens revealed high hemocomptaibility.

Biologically inspired, catechol-coordinated, hierarchical organization of raspberry-like calcium phosphate nanospheres with high specific surface area.

The elaborate design of calcium phosphates (CaP) with a hierarchical structure for biomedical applications is severely restricted due to their instinctive pertinacious irregular agglomeration. Thus, the development of mesoporous CaP with large internal pores is far from satisfactory. In this study, catechol is selected as a modifier to intervene in the precipitation of CaP. Compared to pure CaP with smooth irregular aggregates with an average size of 110 nm, the catechol-intervened CaP (CaP/Cat) samples are raspberry-like nano-spherical assemblies of ca. 25 nm nanoparticles. The obtained spheres possess a mesoporous structure, large interior pores and high specific surface area, which endow them with a high protein adsorption capacity and high DNA delivery efficacy. Catechol is subjected to oxidative polymerization while CaP precipitation occurs. This simultaneous reaction is supposed to play a crucial role in directing the assembling of the CaP/Cat nanospheres. The flexible catechol moiety is shown to be a novel and promising modifier for manufacturing CaP with tunable structures and properties for various applications.

Ultrasonically assisted preparation of poly(acrylic acid)/calcium phosphate hybrid nanogels as pH-responsive drug carriers

Biocompatible, biodegradable and stimuli-responsive nanomaterials can be used as drug carriers and to achieve controlled drug delivery, which is crucial for treating tumors and lowering drug side effects. Calcium phosphate (CaP) nanoparticles and poly(acrylic acid) (PAA) hydrogels can be used as biocompatible and pH-responsive drug carriers. In this study, based on the ultrasound effect, PAA/CaP hybrid nanogels (approximately 100nm, PDI<0.2) are obtained via the cross-linking of CaP nanoparticles and PAA molecules between the Ca2+ ions and –COOH groups. The PAA/CaP hybrid nanogels show good stability in biological media as well as no hemolysis and no cytotoxicity to L02 cells. Moreover, the PAA/CaP hybrid nanogels display an enhanced loading capacity (approximately 32%) for doxorubicin hydrochloride (DOX) compared to pure CaP nanoparticles (approximately 7.5%) and a pH-controlled drug release due to their dissolution in acidic environment. DOX can be delivered into cancer cells by the PAA/CaP hybrid nanogels, which show an inhibitory effect comparable to that of free DOX, although the inhibitory effect is delayed due to the slow release of DOX from the carriers. In vivo, the PAA/CaP hybrid nanogels cannot avoid the capture by the reticuloendothelial system; however, they show passive tumor targeting ability. In brief, the biocompatible, biodegradable and pH-responsive PAA/CaP hybrid nanogels have the potential to act as drug carriers for controlled drug release.