Green synthesis of Zirconium nanoparticles using Punica granatum (pomegranate) peel extract and their antimicrobial and antioxidant potency.

The biosynthesis of metal oxide nanoparticles provides an excellent alternative to the chemical synthesis approach. The aim of the current study was a green and eco-friendly synthesis of zirconium nanoparticles (ZrNPs) from fruit peels of Punica granatum (Pomegranate). The synthesis of ZrNPs was confirmed using a UV-visible spectrophotometer. The functional groups present on surface of ZrNPs were analyzed using FTIR. The average size of obtained ZrNPs was analyzed using SEM and DLS and it was around 20-60 nm. The antimicrobial activity of obtained ZrNPs was tested against Gram-positive strains (Bacillus subtilis and Staphylococcus aureus), Gram-negative strains (Escherichia coli and Klebsiella pneumoniae) and Fungi (Aspergillus niger) by agar well diffusion method. ZrNPs showed maximum zone of inhibition against S. aureus (19 mm) and A. niger (18 mm) at the maximum concentration of 200 µg/mL. The antioxidant scavenging activity of obtained ZrNPs was analyzed using the following methods: DPPH radical scavenging activity, Hydroxyl radical scavenging activity, Ferric reducing antioxidant power and hydrogen peroxide radical scavenging activity. This the first and foremost study on ZrNPs synthesized using P. granatum fruit peel extract reporting their efficacy as antimicrobial agents against Bacteria and Fungi. Considering the tolerance of zirconium towards human body, it can also be used as antimicrobial coating material on human implants.

Origin and significance of Si and O isotope heterogeneities in Phanerozoic, Archean, and Hadean zircon.

Hydrosphere interactions and alteration of the terrestrial crust likely played a critical role in shaping Earth's surface, and in promoting prebiotic reactions leading to life, before 4.03 Ga (the Hadean Eon). The identity of aqueously altered material strongly depends on lithospheric cycling of abundant and water-soluble elements such as Si and O. However, direct constraints that define the character of Hadean sedimentary material are absent because samples from this earliest eon are limited to detrital zircons (ZrSiO4). Here we show that concurrent measurements of Si and O isotope ratios in Phanerozoic and detrital pre-3.0 Ga zircon constrain the composition of aqueously altered precursors incorporated into their source melts. Phanerozoic zircon from (S)edimentary-type rocks contain heterogeneous δ18O and δ30Si values consistent with assimilation of metapelitic material, distinct from the isotopic character of zircon from (I)gneous- and (A)norogenic-type rocks. The δ18O values of detrital Archean zircons are heterogeneous, although yield Si isotope compositions like mantle-derived zircon. Hadean crystals yield elevated δ18O values (vs. mantle zircon) and δ30Si values span almost the entire range observed for Phanerozoic samples. Coupled Si and O isotope data represent a constraint on Hadean weathering and sedimentary input into felsic melts including remelting of amphibolites possibly of basaltic origin, and fractional addition of chemical sediments, such as cherts and/or banded iron formations (BIFs) into source melts. That such sedimentary deposits were extensive enough to change the chemical signature of intracrustal melts suggests they may have been a suitable niche for (pre)biotic chemistry as early as 4.1 Ga.

Multimodal Positron Emission Tomography Imaging to Quantify Uptake of 89Zr-Labeled Liposomes in the Atherosclerotic Vessel Wall.

Nanotherapy has recently emerged as an experimental treatment option for atherosclerosis. To fulfill its promise, robust noninvasive imaging approaches for subject selection and treatment evaluation are warranted. To that end, we present here a positron emission tomography (PET)-based method for quantification of liposomal nanoparticle uptake in the atherosclerotic vessel wall. We evaluated a modular procedure to label liposomal nanoparticles with the radioisotope zirconium-89 (89Zr). Their biodistribution and vessel wall targeting in a rabbit atherosclerosis model was evaluated up to 15 days after intravenous injection by PET/computed tomography (CT) and PET/magnetic resonance imaging (PET/MRI). Vascular permeability was assessed in vivo using three-dimensional dynamic contrast-enhanced MRI (3D DCE-MRI) and ex vivo using near-infrared fluorescence (NIRF) imaging. The 89Zr-radiolabeled liposomes displayed a biodistribution pattern typical of long-circulating nanoparticles. Importantly, they markedly accumulated in atherosclerotic lesions in the abdominal aorta, as evident on PET/MRI and confirmed by autoradiography, and this uptake moderately correlated with vascular permeability. The method presented herein facilitates the development of nanotherapy for atherosclerotic disease as it provides a tool to screen for nanoparticle targeting in individual subjects' plaques.

Zirconium as a suitable reference element for estimating potentially toxic element enrichment in treated wastewater discharge vicinity.

The suitability of a reference element or normalizer used in assessing soil contamination levels using enrichment factor (EF) is important for soil quality assessment and monitoring. This study evaluated the results of using three reference elements Ti, Fe, and Zr for EF determination of Rb and Sr in soils within treated wastewater discharge vicinity, Central Botswana. The upper continental crust (UCC), world average values (WAV), and the local background values (LBV) were used in EF assessment of eight pedons. The elemental concentrations of the soils were determined with portable X-ray fluorescence (pXRF) analyzer. Relationships between the elements were strongly significant between Rb and Ti (r = 0.600, p < 0.01), Rb and Fe (r = 0.735, p < 0.01), Sr and Ti (r = 0.545, p < 0.01), and Sr and Fe (r = 0.841, p < 0.01). Second-level correlation analysis between contamination factor (CF) and EF levels showed Zr as the best reference element for Rb and Sr in the soils. Results from this study provide baseline knowledge necessary for contamination assessment and monitoring of soils with similar environmental conditions.

Effect of Hydrothermal Aging and Beverages on Color Stability of Lithium Disilicate and Zirconia Based Ceramics.

Background and Objectives: All-ceramic prosthesis is widely used in modern dental practice because of its improved physico-mechanical and optical properties. These restorations are exposed to coloring agents from various nutrition and beverages in the oral cavity. Long-term color stability is critical for the success of these restorative materials. The purpose of this in vitro study was to assess the effect of common beverages and mouthwash on the color stability of lithium disilicate (LD), monolithic zirconia (MZ) and bilayer zirconia (BZ) surfaces. Materials and Method: Thirty disc-shaped specimens from each material were fabricated; each group was subdivided (n = 10) according to coffee, green tea and chlorhexidine immersion solutions. The baseline color of ceramic discs was recorded according to the CIE L*a*b* system with a portable spectrophotometer. The second measurement was recorded after 3000 thermocycling and immersion in coloring agents for 7 days. The mean color difference was calculated and data were compared with Kruskal-Wallis and Mann-Whitney post hoc tests (0.05). Results: ΔE values for LD with the immersion of coffee, tea, and Chlorhexidine gluconate (CHG) were 1.78, 2.241 and 1.58, respectively. Corresponding ΔE values for MZ were 5.60, 5.19, and 4.86; marginally higher than the clinically acceptable level of 3.5. Meanwhile, BZ showed better color stability compared to MZ with ΔE values of 4.22, 2.11 and 1.43. Conclusions: Among the ceramics evaluated, LD ceramic was found to be more color stable, while MZ ceramics displayed a higher susceptibility to discoloration. MZ and BZ ceramic colors were significantly altered with coffee immersion, while LD ceramics were more affected by green tea.

Potential use of prostate specific membrane antigen (PSMA) for detecting the tumor neovasculature of brain tumors by PET imaging with 89Zr-Df-IAB2M anti-PSMA minibody.

Tumor angiogenesis has attracted increasing attention because of its potential as a valuable marker in the differential diagnosis of brain tumors as well as a novel therapeutic target. Prostate-specific membrane antigen (PSMA) is expressed by the neovasculature endothelium of some tumors, with little to no expression by the tumor cells or normal vasculature endothelium. The aim of this study was to investigate the potential of PSMA for the evaluation of the tumor neovasculature of various brain tumors and the possibility of detecting PSMA expression in brain tumors using PET imaging with 89Zr-Df-IAB2M (anti-PSMA minibody). Eighty-three tissue specimens including gliomas, metastatic brain tumors, primary central nervous system lymphomas (PCNSL), or radiation necroses were analyzed by immunohistochemical staining with PSMA antibody. 89Zr-Df-IAB2M PET scans were performed in three patients with recurrent high-grade gliomas or metastatic brain tumor. PSMA was highly expressed in the vascular endothelium of high-grade glioma and metastatic brain tumor, whereas PSMA was poorly expressed in the vascular endothelium of PCNSL and radiation necrosis. PSMA expression in high-grade gliomas and a metastatic brain tumor was clearly visualized by PET imaging with 89Zr-Df-IAB2M. Furthermore, a trend toward a positive correlation between the degree of 89Zr-Df-IAB2M uptake and PSMA expression levels in tumor specimens was observed. PET imaging of PSMA using 89Zr-Df-IAB2M may have potential value in the differential diagnosis of high-grade glioma from PCNSL or radiation necrosis as well as in the prediction of treatment efficacy and assessment of treatment response to bevacizumab therapy for high-grade glioma.

Potentially biogenic carbon preserved in a 4.1 billion-year-old zircon.

Evidence of life on Earth is manifestly preserved in the rock record. However, the microfossil record only extends to ∼ 3.5 billion years (Ga), the chemofossil record arguably to ∼ 3.8 Ga, and the rock record to 4.0 Ga. Detrital zircons from Jack Hills, Western Australia range in age up to nearly 4.4 Ga. From a population of over 10,000 Jack Hills zircons, we identified one >3.8-Ga zircon that contains primary graphite inclusions. Here, we report carbon isotopic measurements on these inclusions in a concordant, 4.10 ± 0.01-Ga zircon. We interpret these inclusions as primary due to their enclosure in a crack-free host as shown by transmission X-ray microscopy and their crystal habit. Their δ(13)CPDB of -24 ± 5‰ is consistent with a biogenic origin and may be evidence that a terrestrial biosphere had emerged by 4.1 Ga, or ∼ 300 My earlier than has been previously proposed.

A versatile proximity-dependent probe based on light-up DNA-scaffolded silver nanoclusters.

It is well-known that proximity-dependent probes containing an analyte recognization site and a signal formation domain could be assembled specifically into a sandwich-like structure (probe-analyte-probe) via introducing an analyte. In this work, using the design for zirconium ion (Zr(4+)) detection as the model, we develop a novel and reliable proximity-dependent DNA-scaffolded silver nanocluster (DNA/AgNC) probe for Zr(4+) detection via target-induced emitter proximity. The proposed strategy undergoes the two following processes: target-mediated emitter pair proximity as target recognition implement and the synthesis of DNA/AgNCs with fluorescence as a signal reporter. Upon combination of the rationally designed probe with Zr(4+), the intact templates were obtained according to the -PO3(2-)-Zr(4+)-PO3(2-)- pattern. The resultant structure with an emitter pair serves as a potent template to achieve highly fluorescent DNA/AgNCs. To verify the universality of the proposed proximity-dependent DNA/AgNC probe, we extend the application of the proximity-dependent probe to DNA and adenosine triphosphate (ATP) detection by virtue of a specific DNA complementary sequence and ATP aptamer as a recognition unit, respectively. The produced fluorescence enhancement of the DNA/AgNCs in response to the analyte concentration allows a quantitative evaluation of the target, including Zr(4+), DNA, and ATP with detection limits of ∼3.00 µM, ∼9.83 nM, and ∼0.81 mM, respectively. The proposed probe possesses good performance with simple operation, cost-effectiveness, good selectivity, and without separation procedures.

The interaction of an amino-modified ZrO2 nanomaterial with macrophages-an in situ investigation by Raman microspectroscopy.

Metal oxide nanoparticles (NP) are applied in the fields of biomedicine, pharmaceutics, and in consumer products as textiles, cosmetics, paints, or fuels. In this context, the functionalization of the NP surface is a common method to modify and modulate the product performance. A chemical surface modification of NP such as an amino-functionalization can be used to achieve a positively charged and hydrophobic surface. Surface functionalization is known to affect the interaction of nanomaterials (NM) with cellular macromolecules and the responses of tissues or cells, like the uptake of particles by phagocytic cells. Therefore, it is important to assess the possible risk of those modified NP for human health and environment. By applying Raman microspectroscopy, we verified in situ the interaction of amino-modified ZrO2 NP with cultivated macrophages. The results demonstrated strong adhesion properties of the NP to the cell membrane and internalization into the cells. The intracellular localization of the NP was visualized via Raman depth scans of single cells. After the cells were treated with sodium azide (NaN3) and 2-deoxy-glucose to inhibit the phagocytic activity, NP were still detected inside cells to comparable percentages. The observed tendency of amino-modified ZrO2 NP to interact with the cultivated macrophages may influence membrane integrity and cellular functions of alveolar macrophages in the respiratory system. Graphical abstract Detection of ZrO2 NM at subcellular level.

Elemental analysis of mussels and possible health risks arising from their consumption as a food: The case of Boka Kotorska Bay, Adriatic Sea.

The present study investigated the essential and non-essential elements in cultivated and wild mussels and assessed the health risk arising from their consumption as an impact of rapid growth and intensive production of Mytilus galloprovincialis in the mussel farms of the Boka Kotorska Bay. The concentrations of macro, micro, nonessential and even the small amounts of potentially toxic elements in the cultivated and wild mussels were influenced by industry, tourism and the geohydrology of the Bay. In the case of cultivated mussels, the limiting factor, i.e., the element the elevated concentration of which restricts mussels consumption, was Zr, while in the case of wild mussels the limiting factors were Cr and As. The sites with cultivated mussels stand out as sites with the highest calculated element pollution index, the total hazard index and with higher estimated risk to the health of consumers.

Cationic polyelectrolyte induced separation of some inorganic contaminants and their mixture (zirconium silicate, kaolin, K-feldspar, zinc oxide) as well as of the paraffin oil from water.

The flocculation efficiency of a cationic polyelectrolyte with quaternary ammonium salt groups in the backbone, namely PCA5 was evaluated on zirconium silicate (kreutzonit), kaolin, K- feldspar and zinc oxide (ZnO) suspensions prepared either with each pollutant or with their mixture. The effect of several parameters such as settling time, polymer dose and the pollutant type on the separation efficacy was evaluated and followed by optical density and zeta potential measurements. Except for ZnO, the interactions between PCA5 and suspended particles led to low residual turbidity values (around 4% for kreutzonit, 5% for kaolin and 8% for K-feldspar) as well as to the reduction of flocs settling time (from 1200 min to 30 min and 120 min in case of kaolinit and K-feldspar, respectively), that meant a high efficiency in their separation. The negative value of the zeta potential and flocs size measurements, at the optimum polymer dose, point to contribution from charge patch mechanism for the particles flocculation. A good efficiency of PCA5 in separation of paraffin oil (a minimum residual turbidity of 9.8%) has been also found.

Determination of trace amounts of zirconium in real samples after microwave digestion and ternary complex dispersive liquid-liquid microextraction.

In this study, a ternary Zr(IV) system with 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol (5-Br-PADAP) and fluoride was chosen on the basis of dispersive liquid-liquid microextraction method. Zirconium was extracted into the fine droplets of dichlorobenzene as extracting solvent. These drops dispersed as a cloud in the aqueous sample with the help of ultrasonic waves, and the procedure was done. Finally, atomic absorption spectrometry was applied for the determination of zirconium. The effects of different factors that influence complex formation and extraction, such as pH, amounts of complexing agents, type and volume of the extracting solvent, as well as sonication and centrifuging time, were optimized. Under optimum conditions, the calibration curve was linear in the range of 150.0-800.0 ng mL(-1) with a limit of detection of 44.0 ng mL(-1). Relative standard deviation was calculated to be 4.1 % (n = 7, c = 400.0 ng mL(-1)). The enrichment factor was 80. The proposed method was successfully used to determine the zirconium in several water, wastewater, and soil samples.

Effect of particle deposition parameters on silica coating of zirconia using a chairside air-abrasion device.

PURPOSE: To evaluate the effect of nozzle distance, nozzle angle, and deposition duration on the silica content attained on zirconia by air abrasion. MATERIALS AND METHODS: Disk-shaped zirconia (LAVA, 3M ESPE) (diameter: 10 mm, thickness: 2 mm) specimens (N = 54) were obtained. They were wet-ground finished using 600-, 800-, and 1200-grit silicone carbide abrasive papers in sequence and ultrasonically cleaned. The specimens were mounted in a specially designed apparatus that allowed the chairside air-abrasion device to be operated under standard conditions. Alumina-coated silica particles (CoJet Sand, 3M ESPE) were deposited on the zirconia disk surfaces varying the following parameters: a) nozzle distance (2, 5, 10 mm), and b) deposition duration (5, 13, 20 s) at two nozzle angles (45 and 90 degrees) under 2.5 bar pressure at three locations on each ceramic disk. The specimen surfaces were then gently air dried for 20 s. Silica content in weight percentage (wt%) was measured from 3 surfaces on each disk using Energy Dispersive X-ray Spectroscopy (EDS) (150X) in an area of 0.8 mm x 0.6 mm (n = 3 per group). Surface topographies were evaluated using SEM. Data were analyzed using ANOVA and Tukey's tests (α = 0.05). RESULTS: Nozzle angle (p = 0.003) and deposition duration (p = 0.03) significantly affected the results, but nozzle distance (p = 0.569) did not. A significantly higher amount of silica (wt%) was achieved when the nozzle angle was 45 degrees to the surface in all distance-duration combinations (16.7 to 28.2 wt%) compared to the 90-degree nozzle angle (10.7 to 18.6 wt%) (p < 0.001). The silica amount was significantly higher after 20-s deposition duration than after 13 s (p < 0.05). EDS analysis demonstrated not only Si but also Al, Zr, and O traces on the substrate. SEM images indicated that deposition at a nozzle distance of 2 mm often created cavitations in zirconia. CONCLUSION: Effective silica deposition using a charside air-abrasion device can be achieved when the nozzle is held at 45 degrees to the surface with more than 2-mm nozzle distance for 20 s.

Valorisation of waste ilmenite mud in the manufacture of sulphur polymer cement.

This paper reports the preparation of sulphur polymer cements (SPCs) incorporating waste ilmenite mud for use in concrete construction works. The ilmenite mud raw material and the mud-containing SPCs (IMC-SPCs) were characterised physico-chemically and radiologically. The optimal IMC-SPC mixture had a sulphur/mud ratio (w/w) of 1.05 (mud dose 20 wt%); this cement showed the greatest compressive strength (64 MPa) and the lowest water absorption coefficient (0.4 g cm(-2) at 28 days). Since ilmenite mud is enriched in natural radionuclides, such as radium isotopes (2.0·10(3) Bq kg(-1)(228)Ra and 5.0·10(2) Bq kg(-1)(226)Ra), the IMC-SPCs were subjected to leaching experiments, which showed their environmental impact to be negligible. The activity concentration indices for the different radionuclides in the IMC-SPCs containing 10% and 20% ilmenite mud met the demands of international standards for materials used in the construction of non-residential buildings.

Should finishing, polishing or glazing be performed after grinding YSZ ceramics? A systematic review and meta-analysis.

The present systematic review and meta-analysis aimed to assess the characteristics and consequences of post-processing methods after grinding procedures in YSZ ceramics on its surface roughness and flexural strength. The protocol of this review was made prospectively and is available online in the PROSPERO database (link). Literature searches on PubMed/MEDLINE, EMBASE, Lilacs, Web of Science and Scopus were conducted on December 2022 to select in vitro studies written in English, without publishing-date restrictions, that considered surface characteristics and mechanical properties of YSZ ceramics submitted to grinding and subsequent post-processing surface treatments as an attempt to revert the effect induced by grinding. Two authors independently selected the studies, extracted the data and assessed the risk of bias. Mean differences (Rev-Man 5.1, random effects model, α= 0.05) were obtained by comparing flexural strength and surface roughness values of ground surfaces with at least one post-processing surface treatment (global analysis). Subgroup analyses were performed considering the most prevalent categories of post-processing methods. A total of 33 (out of 4032) studies were eligible and included in the analysis. In the global analysis, ground surfaces showed higher flexural strength than when post-processing methodologies were employed (p< 0.0001). The subgroup analysis showed that only polishing was able to enhance the flexural strength after grinding (p= 0.001); however, when other protocols were used, the ground surface was always superior in terms of flexural strength (p< 0.0001). Post-processing techniques in both the global and sub-group analyses were able to reduce the surface roughness after grinding in YSZ ceramics (p< 0.00001). High heterogeneity was found in all the meta-analyses. Concerning the risk of bias analysis, the included studies had mixed scores for the considered factors. In conclusion, in terms of improving flexural strength and restoring surface roughness after grinding, polishing protocols can be considered the best indication as post-processing treatment after YSZ ceramics adjustments/grinding.

3D flower-like zirconium magnesium oxide nanocomposite for efficient fluoride removal.

A 3D flower-shaped bimetallic nanocomposite zirconium magnesium oxide (ZMO) was prepared first time by the controlled solution combustion method using triethanolamine (TEA) as a fuel and chelating agent. The composite material was used to remove excess fluoride via adsorption. The thermal stability of the adsorbent was characterized by thermogravimetric analysis (TGA). Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FESEM), energy-dispersive X-ray (EDX), and X-ray diffraction (XRD) were used to characterize the adsorbent. The surface charge of the nano adsorbent was determined by Zeta Sizer. The surface area and pore volume of the adsorbent were determined by Brunauer-Emmett-Teller (BET) isotherm and Barrett-Joyner-Halenda (BJH) methods. The adsorption behavior of fluoride was studied systematically varying the pH, contact time, adsorbent dose, and initial fluoride concentration. The adsorption followed the Langmuir isotherm model with a maximum adsorption capacity of 42.14 mg/g. The pseudo-second-order kinetic model was confirmed by the adsorption study. The maximum adsorption efficiency was in the 6-10 pH range. The reaction mechanism was mainly based on ion exchange between hydroxy and fluoride ions which was proven by X-ray photoelectron spectroscopy (XPS). Real water tests indicated that ZMO could be used as a potential defluoridation agent for fluoride containing groundwater treatment.

Efficient fluorescence turn-on probe for zirconium via a target-triggered DNA molecular beacon strategy.

It is well-known that Zr(4+) could selectively bind with two phosphate-functionalized molecules through a coordinate covalent interaction to form a sandwich-structured complex (-PO(3)(2-)-Zr(4+)-PO(3)(2-)-). In this paper, we for the first time converted such interaction into fluorescence sensing systems for Zr(4+) via a target-triggered DNA molecular beacon strategy. In the new designed sensing system, two phosphorylated and pyrene-labeled oligonucleotides were chosen as both recognition and reporter units, which will be linked by target Zr(4+) to form a hairpin structure and bring the two labeled pyrene molecules into close proximity, resulting in a "turn-on" excimer fluorescence signal. Moreover, γ-cyclodextrin was introduced to afford an amplified fluorescence signal and, therefore, provided an improved sensitivity for the target Zr(4+). This allows detection of Zr(4+) with high sensitivity (limit of detection, LOD = 200 nM) and excellent selectivity. The proposed sensing system has also been used for detection of Zr(4+) in river water samples with satisfactory result.

89Zr-labeled dextran nanoparticles allow in vivo macrophage imaging.

Tissue macrophages play a critical role both in normal physiology and in disease states. However, because of a lack of specific imaging agents, we continue to have a poor understanding of their absolute numbers, flux rates, and functional states in different tissues. Here, we describe a new macrophage specific positron emission tomography imaging agent, labeled with zirconium-89 ((89)Zr), that was based on a cross-linked, short chain dextran nanoparticle (13 nm). Following systemic administration, the particle demonstrated a vascular half-life of 3.9 h and was found to be located primarily in tissue resident macrophages rather than other white blood cells. Subsequent imaging of the probe using a xenograft mouse model of cancer allowed for quantitation of tumor-associated macrophage numbers, which are of major interest in emerging molecular targeting strategies. It is likely that the material described, which allows the visualization of macrophage biology in vivo, will likewise be useful for a multitude of human applications.

Articulating spacers used in two-stage revision of infected hip and knee prostheses abrade with time.

BACKGROUND: Articulating spacers used in two-stage revision surgery of infected prostheses have the potential to abrade and subsequently induce third-body wear of the new prosthesis. QUESTIONS/PURPOSES: We asked whether particulate material abraded from spacers could be detected in the synovial membrane 6 weeks after implantation when the spacers were removed for the second stage of the revision. PATIENTS AND METHODS: Sixteen hip spacers (cemented prosthesis stem articulating with a cement cup) and four knee spacers (customized mobile cement spacers) were explanted 6 weeks after implantation and the synovial membranes were removed at the same time. The membranes were examined by xray fluorescence spectroscopy, xray diffraction for the presence of abraded particles originating from the spacer material, and analyzed in a semiquantitative manner by inductively coupled plasma mass spectrometry. Histologic analyses also were performed. RESULTS: We found zirconium dioxide in substantial amounts in all samples, and in the specimens of the hip synovial lining, we detected particles that originated from the metal heads of the spacers. Histologically, zirconium oxide particles were seen in the synovial membrane of every spacer and bone cement particles in one knee and two hip spacers. CONCLUSIONS: The observations suggest cement spacers do abrade within 6 weeks. Given the presence of abrasion debris, we recommend total synovectomy and extensive lavage during the second-stage reimplantation surgery to minimize the number of abraded particles and any retained bacteria.