Direct screening of tetracyclines in water and bovine milk using room temperature phosphorescence detection

Development of europium(III) complex functionalized silica nanoprobe for luminescence detection of tetracycline

Increasing awareness of the health and environment impacts of the antibiotics misuse or overuse, such as tetracycline (TC) in treatment or prevention of infections and diseases, has driven the development of robust methods for their detection in biological, environmental and food systems. In this work, we report the development of a new europium(III) complex functionalized silica nanoprobe (SiNPs-Eu³⁺) for highly sensitive and selective detection of TC residue in aqueous solution and food samples (milk and meat). The nanoprobe is developed by immobilization of Eu³⁺ ion onto the surface of silica nanoparticles (SiNPs) as the emitter and TC recognition unit. The β-diketone configuration of TC can further coordinate with Eu³⁺ steadily on the surface of nanoprobe, facilitating the absorption of light excitation for Eu³⁺ emitter activation and luminescence "off-on" response. The dose-dependent luminescence enhancement of SiNPs-Eu³⁺ nanoprobe exhibits good linearities, allowing the quantitative detection of TC. The SiNPs-Eu³⁺ nanoprobe shows high sensitivity and selectivity for TC detection in buffer solution. Time resolved luminescence analysis enables the elimination of autofluorescence and light scattering for highly sensitive detection of TC in milk and pork mince with high accuracy and precision. The successful development of SiNPs-Eu³⁺ nanoprobe is anticipated to provide a rapid, economic, and robust approach for TC detection in real world samples.

Dendrobium candidum quality detection in both food and medicine agricultural product: Policy, status, and prospective

Dendrobium candidum (DC) is an agricultural product for both food and medicine. It has a variety of beneficial effects on the human body with antioxidant, anti-inflammatory, antitumor, enhancing immune function, and other pharmacological activities. Due to less natural distribution, harsh growth conditions, slow growth, low reproduction rate, and excessive logging, wild DC has been seriously damaged and listed as an endangered herbal medicine variety in China. At present, the quality of DC was uneven in the market, so it is very necessary to detect its quality. This article summarized the methods of DC quality detection with traditional and rapid nondestructive, and it also expounded the correlation between DC quality factor and endophytes, which provides a theoretical basis for a variety of rapid detection methods in macromolecules. At last, this article put forward a variety of rapid nondestructive detection methods based on the emission spectrum. In view of the complexity of molecular structure, the quality correlation established by spectral analysis was greatly affected by varieties and environment. We discussed the possibility of DC quality detection based on the molecular dynamic calculation and simulation mechanism. Also, a multimodal fusion method was proposed to detect the quality. The literature review suggests that it is very necessary to understand the structure performance relationship, kinetic properties, and reaction characteristics of chemical substances at the molecular level by means of molecular chemical calculation and simulation, to detect a certain substance more accurately. At the same time, several modes are combined to form complementarity, eliminate ambiguity, and uncertainty and fuse the information of multiple modes to obtain more accurate judgment results.

Application of Samarium- and Terbium-Sensitized Luminescence via a Multivariate-Based Approach for the Determination of Orbifloxacin

A lanthanide-based optical sensor has been developed for the sensitive and reliable spectrofluorometric determination of the fluoroquinolone antibiotic orbifloxacin (ORLX). Reaction of ORLX and two lanthanide metal ions, Sm(III) and Tb(III), in aqueous buffered solution produced highly fluorescent complexes. Plackett–Burman design (PBD) was used to explore the impact of four factors, pH, temperature (Temp), contact time (CT), and metal volume (MV), on the fluorescence intensity (FI) of the produced complexes. The obtained data showed that pH was the most significant variable. A blend of pH = 5.0, MV = 2.0 mL, T = 25°C, and CT = 10 min was used to achieve the maximum FI. FT-IR and Raman analyses were performed for the crystals of the as-prepared complexes. Obtained data showed shifting in most of the absorption bands, confirming the complexation of ORLX with both metal ions. Job’s method showed that the stoichiometry for the reaction of ORLX with Sm(III) and Tb(III) was 1 : 1. The proposed method was validated following the ICH guidelines. Injection formulation was analyzed successfully with the developed method with high recovery (99.42–100.91%). The detection and quantification limits were 0.987 and 3.289 ng/mL for the ORLX-Sm(III) complex and 1.020 and 3.399 ng/mL for the ORLX-Tb(III) complex, respectively.

Flow Injection Techniques for Tetracycline Quantification: A Review

The multiple therapeutic potentials of tetracycline and its worldwide usage have encouraged researchers to develop various methods for its assay in various matrices and for different purposes. In this regard, different analytical techniques have been exploited. Among those techniques is flow injection (FI), which is an extended family of three generations and five versions. The current manuscript reviews the utilization of FI techniques for developing assay methods for tetracycline. The review covers more than forty methods, since the inception of FI techniques and up to date. The review highlights the advantages of the application of FI techniques for quantification of tetracycline in terms of reagent consumption, sample frequency, accuracy, and practitioner safety, besides instrumentation simplicity and cost-effectiveness. The review also addresses applications to several matrices ranging from simple matrices such as standard solutions and pharmaceutical formulations to complex matrices such as biological fluids and food. Prior to the review, a brief background on the principles and developments of FI techniques is illustrated.

Development of an Electrochemical Sensor Based on Nanocomposite of Fe3O4@SiO2 and Multiwalled Carbon Nanotubes for Determination of Tetracycline in Real Samples

In this work, an electrochemical sensor (GCE/MWCNT/Fe3O4@SiO2) based on a composite of multiwalled carbon nanotubes (MWCNT) and an Fe3O4@SiO2 (MMN) nanocomposite on a glassy carbon electrode (GCE) was developed for the detection of tetracycline (TC). The composite formed promoted an increased electrochemical signal and the stability of the sensor, combining its individual characteristics such as high electrical conductivity and large surface area. The composite material was characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Mössbauer spectroscopy, and scanning electron microscope (SEM). The adsorptive stripping differential pulse voltammetry (AdSDPV) promoted better performance for the electrochemical sensor and greater sensitivity for TC detection. Under optimized conditions, the currents increased linearly with TC concentrations from 4.0 to 36 µmol L−1 (0.997) and from 40 to 64 µmol L−1 (0.994) with detection and quantification limits of 1.67 µmol L−1 and 4.0 µmol L−1, respectively. The sensor was applied in the analysis of milk and river water samples, obtaining recovery values ranging from 91–117%.

A novel fluorescence probe for rapid and sensitive detection of tetracyclines residues based on silicon quantum dots

A novel rapid and sensitive fluorescence probe based on silicon quantum dots (Si QDs) fluorescence was fabricated for selective detection of tetracyclines (TCs) residues. Si QDs were innovatively prepared via facile One-Pot Solvent-Free Method and characterized by TEM, FT-IR, UV absorption, fluorescence, XPS and XRD. In aqueous solution, Cu²⁺ and Si QDs complexed together and the fluorescence of Si QDs quenched (static quenching) to a certain extent. TCs can be early in binding to Cu²⁺ and prevent Si QDs fluorescence quenching. As a consequence, quantitative screening of TCs can be achieved. The assay is highly selective for TCs. Represented by chlortetracycline (CTC), a member of TCs, under optimized conditions, good linear relationship in the range of 11.32-1086.72 nM was obtained, and the detection limit (LOD; S/N ratio = 3) of this assay for CTC is 0.92 nM. It was successfully applied to the determination of CTC in spiked bee honey and total TCs in actual honey samples. And the evaluation of selectivity, reproducibility and stability of the probe were favorable. These results demonstrated that the presented fluorescent probe can be a promising sensing platform for TCs analysis.

Aggregation-induced phosphorescence quenching method for the detection of picric acid based on melamine-passivated Mn-doped ZnS quantum dots

Melamine (MA)-passivated Mn-doped ZnS quantum dots (QDs) were synthesized by a hydrothermal method. The MA-passivated QDs can form a charge-transfer complex with picric acid (PA) at 80 °C, thereby quenching the phosphorescence of the QDs. A sensitive method for detecting PA was established based on this principle of phosphorescence quenching. When the PA concentration ranged from 2.0 to 180 ng mL^-1, the concentration was linearly related to the quenching intensity of the QDs, with a detection limit of 1.4 ng mL^-1. When applied to detect PA in environmental water samples, the proposed method showed superior analytical performance compared with other PA analysis methods. Furthermore, we verified the static quenching mechanism by density functional theory. MA on the surface of QDs and PA formed a stable structure with a binding energy of 12.43 eV.

Effects of ultrasound irradiation on enzymatic hydrolysis of protein and application for the determination of tetracyclines in complex matrices

The widespread use of tetracyclines (TCs) in food animals has led to concerns regarding unsafe residue levels in feed, food and manure. The determination of TCs in such matrices suffers from interference by the interactions between proteins and TCs. Three deproteination methods were compared in this study. In contrast with acid deproteination, which caused a large loss of TCs due to the strong adsorption of TCs on protein precipitates, a normal enzymatic hydrolysis was confirmed to have a merit of effectively releasing TCs from protein matrices, but required treatment time as long as 16 h. The adoption of ultrasound irradiation was proposed to shorten the enzymatic hydrolysis time. After investigating the effects of ultrasound power and irradiation time, the conditions of the ultrasound-enhanced enzymatic hydrolysis were optimized as ultrasound power of 100 W and irradiation time of 6 min. The ultrasound-enhanced enzymatic hydrolysis treatment of 6 min yielded recovery of TCs (from protein-containing matrices) as high as that obtained by the normal enzymatic hydrolysis treatment of 16 h. The acceleration effect of ultrasound irradiation was attributed to ultrasound-induced cavitation, which increased exposure of both the functional groups of trypsin and the C-terminal amino acid in the protein that was a cleavage site for trypsin attack. When the ultrasound-enhanced enzymatic hydrolysis method was used to determine TCs in complex matrices, it was found that this new method achieved recoveries of 89.5, 117.7, 110.4 and 100.0% for oxytetracycline, tetracycline, chlortetracycline and doxycycline, being much higher than those (29.6-39.4%) obtained using the common acid deproteination process. Copyright © 2017 John Wiley & Sons, Ltd.

One-pot carbonization synthesis of europium-doped carbon quantum dots for highly selective detection of tetracycline

The detection of tetracycline is of great significance because of its damaging effects on human health, such as renal toxicity and hemolytic anemia. Any release of tetracycline into the surrounding environment can produce bacterial drug resistance. We develop a new sensitive and selective detection approach for tetracycline in complex water samples by preparing europium-doped carbon quantum dots (Eu-CQDs) through a simple and rapid carbonization method operating at 200 °C for 5 min. The Eu-CQDs are characterized by blue photoluminescence, excitation-wavelength-dependent emission and excellent stability. Importantly, the fluorescence of the Eu-CQDs can be quenched efficiently by tetracycline, based on the strong inner filter effect mechanism between Eu-CQDs and tetracycline, making the fluorescence intensity ratio (I ₀/I) of the Eu-CQDs at 465 nm correlate linearly with the concentration of tetracycline in the range of 0.5-200 μM, with a limit of detection of 0.3 μM. This shows the broad applicability of the Eu-CQDs in pursuing the concepts of simplicity and specificity for analytical purposes.

An inner filter effect based sensor of tetracycline hydrochloride as developed by loading photoluminescent carbon nanodots in the electrospun nanofibers

The inner filter effect (IFE), which results from the absorption of the excitation or emission light by absorbers, has been employed as an alternative approach in sensing systems due to its flexibility and simplicity. In this work, highly photoluminescent carbon nanodots (CDs), which were simply prepared through a new one-step microwave synthesis route, were loaded in electrospun nanofibers, and the obtained nanofibers were then successfully applied to develop a fluorescent IFE-based visual sensor for tetracycline hydrochloride (Tc) sensing in milk. This developed visual sensor has high selectivity owing to the requirements of the spectral overlap between the CDs and Tc, showing high promise in sensing chemistry with an efficient response and economic effect.

Preparation of multifunctional magnetic–fluorescent nanocomposites for analysis of tetracycline hydrochloride

Magnetic quantum dots were effective materials for detection of tetracycline hydrochloride with various concentrations.

Highly selective manganese-doped zinc sulfide quantum dots based label free phosphorescent sensor for phosphopeptides in presence of zirconium (IV)

We report a room-temperature phosphorescence (RTP) sensor for phosphopeptides based on zirconium (IV)-modulated mercaptopropionic acid (MPA)-capped Mn-doped ZnS quantum dots (QDs). This sensor incorporates the advantages of the well-known Zr(4+)-phosphopeptide affinity pair and the RTP properties of doped QDs. The RTP of Mn-doped ZnS QDs capped with MPA can be effectively quenched by Zr(4+). The high affinity of phosphopeptides to Zr(4+) enables the dissociation of the ion from the surface of MPA-capped ZnS QDs, thereby forming a stable complex with phosphopeptides in the solution, and recovering the RTP of the QDs. The Zr(4+)-induced RTP quenching and subsequent phosphopeptide-induced RTP recovery for MPA-capped ZnS QDs provide a solid basis for the present RTP sensor based on QDs for the detection of phosphopeptides. The detection limit for phosphopeptides is 0.9ngmL(-1), the relative standard deviations is 2.5%, and the recovery of urine and serum samples with phosphopeptides addition rangs from 96% to 105% at optimal conditions. The proposed method was successfully applied to biological fluids and obtained satisfactory results.

Rapid colorimetric sensing of tetracycline antibiotics with in situ growth of gold nanoparticles

A colorimetric assay utilizing the formation of gold nanoparticles was developed to detect tetracycline antibiotics in fluidic samples. Tetracycline antibiotics showed the capability of directly reducing aurate salts into atomic gold which form gold nanoparticles spontaneously under proper conditions. The resulted gold nanoparticles showed characteristic plasmon absorbance at 526 nm, which can be visualized by naked eyes or with a spectrophotometer. UV-vis absorbance of the resulted gold nanoparticles is correlated directly with the concentrations of tetracycline antibiotics in the solution, allowing for quantitative colorimetric detection of tetracycline antibiotics. Reaction conditions, such as pH, temperature, reaction time, and ionic strength were optimized. Sensitivity of the colorimetric assay can be enhanced by the addition of gold nanoparticle seeds, a LOD as low as 20 ng mL(-1) can be achieved with the help of seed particles. The colorimetric assay showed minimum interference from ethanol, methanol, urea, glucose, and other antibiotics such as sulfonamides, amino glycosides etc. Validity of the method was also evaluated on urine samples spiked with tetracycline antibiotics. The method provides a broad spectrum detection method for rapid and sensitive detection of reductive substances such as tetracycline antibiotics in liquid and biological samples.

Rapid screening of multiple antibiotic residues in milk using disposable amperometric magnetosensors

Disposable amperometric magnetosensors, involving a mixture of modified-magnetic beads (MBs), for the multiplex screening of cephalosporins (CPHs), sulfonamides (SAs) and tetracyclines (TCs) antibiotic residues in milk are reported for the first time in this work. The multiplexed detection relies on the use of a mixture of target specific modified magnetic beads (MBs) and application of direct competitive assays using horseradish peroxidase (HRP)-labeled tracers. The amperometric responses measured at -0.20 V vs. the Ag pseudo-reference electrode of screen-printed carbon electrodes (SPCE) upon the addition of H2O2 in the presence of hydroquinone (HQ) as redox mediator, were used to monitor the extent of the different affinity reactions. The developed methodology, involving a simple and short pretreatment, allowed discrimination between no contaminated UHT and raw milk samples and samples containing antibiotic residues at the maximum residue limits (MRLs). The usefulness of the multiplexed magnetosensor was demonstrated by analyzing spiked milk samples in only 5 min. The results demonstrated that a clear discrimination of milk samples contaminated with antibiotics at their MRL level or their mixtures, allowing the identification of milk not complying with current legislation. These features make the developed methodology a promising alternative in the development of user-friendly devices for on-site analysis to ensure quality control for dairy products.

Maxillary sinus floor elevation with a tissue-engineered bone composite of deciduous tooth stem cells and calcium phosphate cement in goats

The study aimed to assess the effect of maxillary sinus floor elevation with tissue-engineered bone constructed from deciduous tooth stem cells (DTSCs) and calcium phosphate cement (CPC). The stem cells from goat deciduous teeth (SGDs) were isolated and transfected by means of the adenovirus with an enhanced green fluorescent protein gene (AdEGFP). As many as 18 bilateral maxillary sinuses of nine goats were randomly allocated into three groups (n = 6/group): group A (SGDs-CPC compound), group B (CPC alone) and group C (autogenous bone obtained from an iliac crest). All the samples were evaluated by computed tomography (CT), histology and histomorphometric analysis. Furthermore, the fate of implanted SGDs was traced using an immunohistochemical staining method in the decalcified samples. SGDs might be differentiated into osteoblasts in an osteogenic medium. In the present study, three-dimensional CT analysis showed that the volume of newly formed bone in group A was greater than that in the other two groups. After a healing period of 3 months, sequential analyses of triad-colour fluorescence labelling, histology and histomorphology indicated that the SGDs-CPC compound primarily promoted bone formation and mineralization at 2 and 3 months after the operation. Moreover, the areas of new bone formation in elevated sinuses were 41.82 ± 6.24% in the SGDs-CPC group, which was significantly higher than the 30.11 ± 8.05% in the CPC-alone group or the 23.07 ± 10.21% in the autogenous bone group. Immunohistochemical staining revealed that GFP and OCN were both expressed in the new bone tissue for the samples with eGFP, which suggested that the implanted SGDs might have contributed to new bone formation on the elevated sinus floor. SGDs can promote new bone formation and maturation in the goat maxillary sinus, and the tissue-engineered bone composite of SGDs and CPC might be a potential substitute for existing maxillary sinus floor elevation methods. Copyright © 2014 John Wiley & Sons, Ltd.

A quantum dot-based immunoassay for screening of tetracyclines in bovine muscle

A reliable and robust direct screening methodology based on a quantum dot (QD) fluorescent immunoassay has been developed to detect trace levels of different antibiotic species from the family of the tetracyclines (e.g., oxytetracycline, tetracycline, chlortetracycline, and doxycycline) in contaminated bovine muscle tissues. First, the synthesis and characterization of a new immunoprobe (oxytetracycline-bovine serum albumin-QD) has been carried out for its further application in the development of a competitive fluorescent QD-immunoassay. The developed fluoroimmunoassay provides sensitive and binary "yes/no" responses being appropriate for the screening of this family of antibiotics above or below a preset concentration threshold. The detection limit achieved with this strategy, 1 μg/L in aqueous media and 10 μg/kg in bovine muscle samples, is 10-fold lower than the maximum level concentration allowed by International Legislation in muscle tissue, enabling suitable and efficient screening of the antibiotics.

One-pot synthesis of high fluorescent carbon nanoparticles and their applications as probes for detection of tetracyclines

Herein, a novel strategy for synthesizing fluorescent carbon nanoparticles (CPs) with a quantum yield of approximately 7.1% has been well established by mixing l-cysteine, diphosphorus pentoxide and water. Compared with other current protocols, the method described here displayed various advantages including friendly manipulations, low cost, and rapid reactions. Subsequently, we applied the CPs prepared here for detections of tetracyclines (TCs). Briefly, the fluorescence intensity of CPs was quenched once TCs were introduced. Based on this phenomenon, TCs were analyzed respectively accompanyed with satisfactory detection limits and linear ranges. Significantly, the practicability of this sensing method was further validated by assaying TC in human urine samples and pharmaceutical preparations, confirming its potential to broaden avenues for detecting TCs. Additionally, the CPs could serve as fluorescent powder and ink followed by a simple post-treatment, suggesting their promising applications.

Determination of tetracycline in milk by using nucleotide/lanthanide coordination polymer-based ternary complex

The meta-organic coordination polymers have been emerged as fascinating nanomaterials because of their tunable nature. In this work, we employed lanthanide coordination polymer self-assembled from adenosine monophosphate (AMP) and europium ion (Eu(3+)) as receptor reagent and citrate (Cit) as ancillary ligand to construct a fluorescent sensor for the detection of tetracycline (Tc) in milk. The co-coordination of Cit and Tc with Eu(3+) on the surface of the coordination polymer AMP/Eu leads to the formation of ternary complex which emitted strong fluorescence due to the removal of coordinated water molecules and an intramolecular energy transfer from Tc to Eu(3+). The fluorescent intensity of Eu(3+) displayed a good linear response to Tc concentrations in the range of 0.1-20 μM with a detection limit of 60 nM. This method was successfully applied to determine the levels of Tc in milk, which is the first application of coordination polymer as a fluorescent sensor in real sample. Compared with other Eu(3+)-based fluorescent methods for Tc detection, the presented method allows simple, direct analysis of Tc without requiring special reaction media or complicated prepreparation processes. This straightforward strategy could be extended to the preparation of other lanthanide coordination polymer-based fluorescent probes for applications in biosensing, imaging, drug delivery, and so on.

Simultaneous determination of doxycycline and chlortetracycline in real samples by europium-sensitized luminescence

A simple luminescent methodology for the simultaneous determination of doxycycline and chlortetracycline in pharmaceutical preparations and human urine is proposed. Since the native fluorescence of both analytes is negligible, this method takes advantage of the lanthanide-sensitized luminescence, which provides increased sensitivity. Due to the strong overlapping between the luminescence spectra of both europium complexes, the use of luminescence decay curves to resolve mixtures of the analytes is proposed, particularly as these curves are more selective. A factorial design, with three levels per factor, coupled to a central composite design was selected to obtain a calibration matrix of 13 standards plus one blank sample, which were processed with a partial least-squares analysis. In order to assess the effectiveness of the proposed method, a prediction set of 10 synthetic samples was analyzed, and recovery percentages between 95 and 104% were obtained. Limits of detection, calculated by means of a new criterion, were 3.27 and 1.06 μg L(-1) for doxycycline and chlortetracycline, respectively. The method was tested in three different pharmaceutical preparations containing the analytes, with average recovery percentages of 99.4 ± 1.8 for doxycycline and 100.5 ± 2.1 for chlortetracycline. Moreover, a central composite design was also developed to obtain a calibration matrix that made feasible the simultaneous determination of both tetracyclines in human urine samples. In this case, average recovery percentages were 98.0 ± 4.4 and 97.8 ± 4.6 for doxycycline and chlortetracycline, respectively. No extraction method or prior separation of the analytes was needed.

Maxillary sinus floor elevation using a tissue-engineered bone with calcium-magnesium phosphate cement and bone marrow stromal cells in rabbits

The objective of this study was to assess the effects of maxillary sinus floor elevation with a tissue-engineered bone constructed with bone marrow stromal cells (bMSCs) and calcium-magnesium phosphate cement (CMPC) material. The calcium (Ca), magnesium (Mg), and phosphorus (P) ions released from calcium phosphate cement (CPC), magnesium phosphate cement (MPC), and CMPC were detected by inductively coupled plasma atomic emission spectroscopy (ICP-AES), and the proliferation and osteogenic differentiation of bMSCs seeded on CPC, MPC, and CMPC or cultured in CPC, MPC, and CMPC extracts were measured by MTT analysis, alkaline phosphatase (ALP) activity assay, alizarin red mineralization assay, and real-time PCR analysis of the osteogenic genes ALP and osteocalcin (OCN). Finally, bMSCs were combined with CPC, MPC, and CMPC and used for maxillary sinus floor elevation in rabbits, while CPC, MPC, or CMPC without cells served as control groups. The new bone formation in each group was detected by histological finding and fluorochrome labeling at weeks 2 and 8 after surgical operation. It was observed that the Ca ion concentrations of the CMPC and CPC scaffolds was significantly higher than that of the MPC scaffold, while the Mg ions concentration of CMPC and MPC was significantly higher than that of CPC. The bMSCs seeded on CMPC and MPC or cultured in their extracts proliferated more quickly than the cells seeded on CPC or cultured in its extract, respectively. The osteogenic differentiation of bMSCs seeded on CMPC and CPC or cultured in the corresponding extracts was significantly enhanced compared to that of bMSCs seeded on MPC or cultured in its extract; however, there was no significant difference between CMPC and CPC. As for maxillary sinus floor elevation in vivo, CMPC could promote more new bone formation and mineralization compared to CPC and MPC, while the addition of bMSCs could further enhance its new bone formation ability significantly. Our data suggest that CMPC possesses moderate biodegradability and excellent osteoconductivity, which may be attributed to its Ca and Mg ion composition, and the tissue-engineered bone constructed of CMPC and bMSCs might be a potential alterative graft for maxillofacial bone regeneration.

Luminescence sensors applied to water analysis of organic pollutants--an update

The development of chemical sensors for environmental analysis based on fluorescence, phosphorescence and chemiluminescence signals continues to be a dynamic topic within the sensor field. This review covers the fundamentals of this type of sensors, and an update on recent works devoted to quantifying organic pollutants in environmental waters, focusing on advances since about 2005. Among the wide variety of these contaminants, special attention has been paid polycyclic aromatic hydrocarbons, pesticides, explosives and emerging organic pollutants. The potential of coupling optical sensors with multivariate calibration methods in order to improve the selectivity is also discussed.

Long-term outcome of cryopreserved bone-derived osteoblasts for bone regeneration in vivo

Cryopreserved bone-derived osteoblasts (CBOs) have been considered as a promising cell source for bone regeneration. Previous studies have demonstrated that CBOs had good proliferation and osteogenicity. However, the long-term outcome of CBOs in vivo still remains unknown. In this experiment, we applied CBOs combined with calcium phosphate cement (CPC) to augment maxillary sinus in canine, computer tomography, polychrome labeling, biomechanical tests, fluorescent immunohistochemistry staining and histological analysis were used to analyze the property and mineralization process of the tissue-engineered bone preclinical application. Our results showed that CBOs combined with CPC could promote bone regeneration, dramatically maintain the height, volume and biomechanical property of augmented maxillary sinus. Furthermore, the tissue-engineered bone was more mature than scaffold alone or autogenous bone, and bone formation and remodeling were still apparent 20 months postoperatively. Additionally, 4 months after surgery might be the suitable time point for implants placement in the regenerated bone. These results also indicate that cryopreserved bone may be a potential source of osteoblasts for maxillary sinus augmentation.

Systematic evaluation of a tissue-engineered bone for maxillary sinus augmentation in large animal canine model

The objective of this study is to systematically evaluate the effects of a tissue-engineered bone complex for maxillary sinus augmentation in a canine model. Twelve sinus floor augmentation surgeries in 6 animals were performed bilaterally and randomly repaired with the following 3 groups of grafts: group A consisted of tissue-engineered osteoblasts/beta-TCP complex (n=4); group B consisted of beta-TCP alone (n=4); group C consisted of autogenous bone obtained from iliac crest as a positive control (n=4). All dogs had uneventful healings following the surgery. Sequential polychrome fluorescent labeling, maxillofacial CT, microhardness tests, as well as histological and histomorphometric analyses indicated that the tissue-engineered osteoblasts/beta-TCP complex dramatically promoted bone formation and mineralization and maximally maintained the height and volume of elevated maxillary sinus. By comparison, both control groups of beta-TCP or autologous iliac bone showed considerable resorption and replacement by fibrous or fatty tissue. We thus conclude that beta-TCP alone could barely maintain the height and volume of the elevated sinus floor, and that the transplantation of autogenous osteoblasts on beta-TCP could promote earlier bone formation and mineralization, maximally maintain height, volume and increase the compressive strength of augmented maxillary sinus. This tissue engineered bone complex might be a better alternative to autologous bone for the clinical edentulous maxillary sinus augmentation.

Implementation of terbium-sensitized luminescence in sequential-injection analysis for automatic analysis of orbifloxacin

Orbifloxacin (ORBI) is a third-generation fluoroquinolone developed exclusively for use in veterinary medicine, mainly in companion animals. This antimicrobial agent has bactericidal activity against numerous gram-negative and gram-positive bacteria. A few chromatographic methods for its analysis have been described in the scientific literature. Here, coupling of sequential-injection analysis and solid-phase spectroscopy is described in order to develop, for the first time, a terbium-sensitized luminescent optosensor for analysis of ORBI. The cationic resin Sephadex-CM C-25 was used as solid support and measurements were made at 275/545 nm. The system had a linear dynamic range of 10-150 ng mL(-1), with a detection limit of 3.3 ng mL(-1) and an R.S.D. below 3% (n = 10). The analyte was satisfactorily determined in veterinary drugs and dog and horse urine.