Phosphate-buffered Saline Samples Research Articles

Effect of incorrect storage of bull semen samples on sperm morphology assessment

Thirteen pairs of bull semen samples were assessed. One of each pair of samples was inadvertently stored in phosphate buffered saline (PBS) that was used for analysis of motility immediately after collection. Other sample of the pair that was correctly stored in buffered formol saline (BFS) was assessed later. Proportion of morphologically normal sperm was different (p = 0.0021) between the 2 storage methods. Most of the abnormalities in the PBS samples were loose and detached heads. Closer examination of these sperm illustrated changes in the composition of the tail, with an apparent loss of the plasma membrane. This serendipitous error allowed documentation of the importance of correct storage of semen samples for morphological assessment of sperm, and the tertiary defects detected with the incorrect storage of semen samples in semen extender. Tertiary defects should always be considered a possibility during morphological assessment of sperm via spermiogram.

Magnesium-zinc-graphene oxide nanocomposite scaffolds for bone tissue engineering

The aim of this study was to fabricate and evaluate magnesium-zinc-graphene oxide nanocomposite scaffolds for bone tissue engineering. For this reason, Mg-6Zn, Mg-6Zn-1GO, and Mg-6Zn-2GO scaffolds were fabricated by the powder metallurgy method. The porosity level and also the pore size of the scaffolds were evaluated by SEM which varied from 40 to 46% and 200 to 500 μm, respectively. The chemical composition and microstructure of the scaffolds were characterized by XRD and SEM equipped with EDS; the presence of Mg, Zn, C, and O elements in the structure of the scaffolds was shown. Also, the elemental map confirmed the existence of magnesium, zinc, carbon, and oxygen in the structure of the scaffold. The mechanical properties of the scaffolds were investigated by the compression test; the results showed that by the addition of graphene oxide to the structure, the compressive strength of the samples increased from 5 to 8 MPa. Electrochemical corrosion polarization tests were conducted to evaluate the corrosion resistance of the samples immersed in simulated body fluid (SBF). Furthermore, the biodegradability of the scaffolds was determined by immersion of the samples in phosphate-buffered saline (PBS). The results demonstrated that the polarization resistance value and the corrosion rate for different formulations including Mg-6Zn, Mg-6Zn-1GO, and Mg-6Zn-2GO were 41.58, 35.48, and 55.40 Ω.cm2 followed by 10.60, 14.83, and 9.06 mm.year−1, respectively. Based on the results, the Mg-6Zn-2GO formulation presented the best corrosion resistance among the samples were investigated, which confirmed the results of the immersion test. Moreover, the MTT assay proved that the extract of Mg-6Zn-2GO scaffolds was not cytotoxic in contact with L-929 cells which validated the studied scaffolds for bone tissue applications.

Effect of segmental motion on hydrolytic degradation of polyglycolide in electro-spun fiber mats.

Recently, environmentally degradable polymers have received great attention from the perspective of sustaining the aquatic environment. To control the degradation behavior of solid polymer materials in an aqueous phase, it is crucial to better understand the thermal molecular motion of polymer chains in water. We herein focus on polyglycolide (PGA), which is one of the representative aliphatic polyesters that are hydrolytically degradable. Three kinds of fiber mats of PGA with different fiber diameters and comparable crystallinities were prepared using an electrospinning method. Our choice of fiber mats was because the ratio of the surface area, where the hydrolytic degradation starts to occur, to the volume was larger than that for the films. Dynamic mechanical analysis (DMA) enabled us to gain direct access to the dynamic glass transition temperature (Tgα) of PGA in the fiber mats both in dry gaseous nitrogen and liquid water. The Tgα value varied not only with the presence of water molecules, but also with the fiber diameter, or the specific surface area. The degradation behavior of PGA fiber mats was examined by immersing the samples in phosphate-buffered saline at various temperatures. When the segmental motion of PGA in the fiber mats was released, the apparent crystallinity of the mats increased, meaning that PGA amorphous chains were cleaved and thus partially eluted into the aqueous phase. It was also shown that partially cleaved chains crystallized.

Evaluation of optical features of fibronectin fibrils by backscattering polarization imaging

Polarization imaging provides an effective and convenient approach for examining the structural and optical features of scattering media. The present study utilizes a backscattering polarization imaging system to evaluate and compare the polarization features of three different fibronectin (FN) samples: (1) fibronectin-free in phosphate-buffered saline (PBS) solution, (2) fibronectin protein (PFN), and (3) fibrillated fibronectin (FFN). It is shown that the three samples can be qualitatively discriminated via a simple naked-eye observation of the Mueller matrix imaging results. Furthermore, a more quantitative evaluation of the polarization properties of the three samples can be obtained from an inspection of the Mueller Matrix Transformation (MMT) parameters and Frequency Distribution Histogram (FDH) statistics for the pixel intensities of the Mueller matrix elements. The results show that the PFN and PBS samples have isotropic properties, while the FFN sample has anisotropic properties. Overall, the results confirm that the proposed backscattering polarization imaging system provides a feasible means of differentiating between different fibronectin-containing biological samples. It thus has significant potential for various biomedical diagnosis applications, including early-stage cancer detection.

Development of a Highly Specific Fluoroimmunoassay for the Detection of Doxycycline Residues in Water Environmental and Animal Tissue Samples.

Doxycycline (DOX) and its metabolite residues in food and the environment pose a serious threat to human health and the ecological environment. In this work, a novel method, termed competitive fluoroimmunoassays (cFIA), based on monoclonal antibody (mAb) bio-conjugated CdSe/ZnS core-shell quantum dots (QDs), was developed for sensitive and rapid bioanalyses of DOX in natural water and commercial meats. After the optimization of the experimental conditions, 1 μg mL-1 of coating antigen and 0.5 μg mL-1 of QD-labeled mAb were used for the establishment of the cFIA. With this assay, the 50% inhibition concentration was found to be 0.35 ng mL-1 of DOX in phosphate-buffered saline samples, and the limit of detection was 0.039 ng mL-1 with minor cross-reactivity to other tetracycline members. The recoveries from natural water and commercial meats spiked with DOX concentrations of 10-600 ng mL-1 were 81.3-109.8%, and standard deviation were all below 12%. Levels measured with the QD-cFIA for thirty authentic samples were confirmed by high-performance liquid chromatography with good correlations. These results indicate that QD-cFIA is sultable for the rapid and quantitative detection of DOX residue in environmental and food samples.

Multilayer self-assembled kappa carrageenan/ chitosan: Heparin coating on Mg alloys for improving blood compatibility

The study aims to develop a layer-by-layer (LbL) self-assembled coating of Kappa carrageenan (KC) and heparin-loaded chitosan nanoparticles on the AZ91 alloy modified using micro-arc oxidation (MAO) to control its high corrosion rate and improve the hemocompatibility. In this regard, after the MAO process, polyethylene imine (PEI) coating was initially coated on the AZ91 samples. Heparin was loaded on chitosan nanoparticles (chitosan: heparin) with an average size of 55–130 nm. Afterward LBL self-assembled process was performed to deposit subsequent Chitosan: heparin and KC layers on MAO modified AZ91 (KC/Chitosan: heparin). The LbL process was repeated for 10,20, and 30 layers to get a uniform coating with desired electrochemical and biological properties. The electrochemical performance of the samples in phosphate-buffered saline (PBS, pH= 7.4) showed a significant improvement in the corrosion resistance of AZ91 samples after a two-step MAO and 30-layer LbL coating. Moreover, the heparin release from the multilayered coated samples was enhanced by increasing the number of layers. Finally, the determination of blood cell count (red blood cells, white blood cells, and platelets) and platelet adhesion indicated that controlled release of heparin from the coating resulted in a significant improvement of hemocompatibility. Overall, this multilayer KC/Chitosan: heparin coating with significant corrosion resistivity and hemocompatibility could have the potential for cardiovascular stent applications.

A Novel Propidium Monoazide-Based PCR Assay Can Measure Viable Uropathogenic E. coli In Vitro and In Vivo.

BackgroundPolymerase chain reaction (PCR) is an important means by which to study the urine microbiome and is emerging as possible alternative to urine cultures to identify pathogens that cause urinary tract infection (UTI). However, PCR is limited by its inability to differentiate DNA originating from viable, metabolically active versus non-viable, inactive bacteria. This drawback has led to concerns that urobiome studies and PCR-based diagnosis of UTI are confounded by the presence of relic DNA from non-viable bacteria in urine. Propidium monoazide (PMA) dye can penetrate cells with compromised cell membranes and covalently bind to DNA, rendering it inaccessible to amplification by PCR. Although PMA has been shown to differentiate between non-viable and viable bacteria in various settings, its effectiveness in urine has not been previously studied. We sought to investigate the ability of PMA to differentiate between viable and non-viable bacteria in urine.MethodsVarying amounts of viable or non-viable uropathogenic E. coli (UTI89) or buffer control were titrated with mouse urine. The samples were centrifuged to collect urine sediment or not centrifuged. Urine samples were incubated with PMA and DNA cross-linked using blue LED light. DNA was isolated and uidA gene-specific PCR was performed. For in vivo studies, mice were inoculated with UTI89, followed by ciprofloxacin treatment or no treatment. After the completion of ciprofloxacin treatment, an aliquot of urine was plated on non-selective LB agar and another aliquot was treated with PMA and subjected to uidA-specific PCR.ResultsPMA’s efficiency in excluding DNA signal from non-viable bacteria was significantly higher in bacterial samples in phosphate-buffered saline (PBS, dCT=13.69) versus bacterial samples in unspun urine (dCT=1.58). This discrepancy was diminished by spinning down urine-based bacterial samples to collect sediment and resuspending it in PBS prior to PMA treatment. In 3 of 5 replicate groups of UTI89-infected mice, no bacteria grew in culture; however, there was PCR amplification of E. coli after PMA treatment in 2 of those 3 groups.ConclusionWe have successfully developed PMA-based PCR methods for amplifying DNA from live bacteria in urine. Our results suggest that non-PMA bound DNA from live bacteria can be present in urine, even after antibiotic treatment. This indicates that viable but non-culturable E. coli can be present following treatment of UTI, and may explain why some patients have persistent symptoms but negative urine cultures following UTI treatment.

Anti-fibrosis attributes: UHPLC-MS/MS-based pharmacokinetics profiling of a novel autotaxin inhibitor with excellent in vivo efficacy in rat.

3,4-Difluorobenzyl(1-ethyl-5-(4-((4-hydroxypiperidin-1-yl)-methyl)thiazol-2-yl)-1H-indol-3-yl)carbamate (NAI59), a small molecule with outstanding therapeutic effectiveness to anti-pulmonary fibrosis, was developed as an autotaxin inhibitor candidate compound. To evaluate the pharmacokinetics and plasma protein binding of NAI59, a UPLC-MS/MS method was developed to quantify NAI59 in plasma and phosphate-buffered saline. The calibration curve linearity ranged from 9.95 to 1990.00ng/mL in plasma. The accuracy was -6.8 to 5.9%, and the intra- and inter-day precision was within 15%. The matrix effect and recovery, as well as dilution integrity, were within the criteria. The chromatographic and mass spectrometric conditions were also feasible to determine phosphate-buffered saline samples, and it has been proved that this method exhibits good precision and accuracy in the range of 9.95-497.50ng/mL in phosphate-buffered saline. This study is the first to determine the pharmacokinetics, absolute bioavailability, and plasma protein binding of NAI59 in rats using this established method. Therefore, the pharmacokinetic profiles of NAI59 showed a dose-dependent relationship after oral administration, and the absolute bioavailability in rats was 6.3%. In addition, the results of protein binding showed that the combining capacity of NAI59 with plasma protein attained 90% and increased with the increase in drug concentration.

Integrated sample desalting, enrichment, and ionization on an omniphobic glass slide for direct mass spectrometry analysis

Direct and rapid mass spectrometry (MS) analysis is desired for many applications including environmental monitoring, forensic analysis, chemical and biological defense, and point-of-care testing. However, sample pretreatment is often necessary for analyzing targets from complex matrices using MS due to ion suppression. To achieve rapid MS analysis calls for simple and efficient solutions for sample processing and ionization. Here, a simple sample pretreatment and ionization workflow is reported, which achieves sample desalting, enrichment, and ionization on a single glass slide. Desalting is achieved based on crystallization and re-dissolution-induced spontaneous separation of analytes and salt. Efficient sample enrichment is achieved during the crystallization process by modifying the glass surface with an omniphobic coating. Finally, vibrating sharp-edge spray ionization is employed to ionize the target molecules directly on the glass slide. Thus, all the necessary sample operations prior to MS analysis are completed on the sample glass slide. Efficient sample enrichment on the omniphobic glass slide is first visualized using food dyes. The benefits of the desalting and enrichment steps for detecting macrolide antibiotics in 1× phosphate buffered saline (PBS) solutions are demonstrated by comparing samples with different treatment procedures. Finally, quantification of macrolide antibiotics from PBS and serum samples is demonstrated. A linear range between 2nM and 10μM has been achieved for the serum sample with a limit of detection of 1nM. A simple, flexible, low-cost, and highly integrated workflow for detecting target molecules from complex matrices using MS is demonstrated. This method will be valuable to many applications that require rapid and efficient MS analysis of complex samples.

Apatite‐like forming ability, porosity, and bond strength of calcium aluminate cement with chitosan, zirconium oxide, and hydroxyapatite additives

This study evaluated the effect of chitosan, zirconium oxide, and hydroxyapatite on the apatite-like forming ability, porosity, and bond-strength of calcium-aluminate cements (C). Three hundred bovine root-slices were assigned to one of five groups, according to the material: MTA, C, C + chitosan (Cchi), C + zirconium oxide (Czio), and C + hydroxyapatite (Chap), and within each group, two subgroups, according to the immersion: deionized water or phosphate-buffered saline (PBS) up to 14 days. Assessments (n=10) of apatite-like forming ability were performed using scanning-electron microscopy, energy-dispersive x-ray spectroscopy, Fourier-transform infrared spectroscopy, and x-ray diffraction. PBS was evaluated for pH and Ca2+ release (n=10). Bond-strength was analyzed by push-out test (n=10) and porosity by micro-CT (n=10). Chemical and push-out data were analyzed by ANOVA and Tukey's tests (α=.05). Porosity data were analyzed by the Kruskal-Wallis and SNK tests (α=.05). Similar Ca/P ratios were observed between all groups (p > .05). The pH of MTA and Cchi were higher than that of other cements at d 3 and 6 (p < .05). Cchi had a higher release of Ca2+ up to 6 days (p < .05). All cements had lower porosity after PBS (p < .05). Cchi and Chap had similar porosity reduction (p > .05), and were higher than MTA, C, and Czio (p < .05). Cchi had higher bond-strength than the other groups (p < .05). PBS samples had higher bond-strength (p < .05). All cements had hydroxyapatite deposition and the chitosan blend had the lowest porosity and the highest bond-strength.

Tendon Multiscale Structure, Mechanics, and Damage Are Affected by Osmolarity of Bath Solution.

One of the most common bath solutions used inmusculoskeletal mechanical testing is phosphate buffered saline (PBS). In tendon, swelling induced by physiological PBS results in decreased tendon modulus and induces microstructural changes. It is critical to evaluate the multiscale mechanical behavior of tendon under swelling to interpret prior work and provide information to design future studies. We compared the effects of physiological PBS and 8% polyethylene glycol and saline bathing solutions on tendon multiscale tendon mechanics and damage as well as microstructure with TEM in order to understand the effect of swelling on tendon. At the tissue level, tendons in PBS had a lower modulus than SPEG samples. PBS samples also showed an increased amount of non-recoverable sliding, which is an analog for microscale damage. SPEG had a higher microscale to tissue-scale strain ratio, showing the fibrils experienced less strain attenuation. From the TEM data, we showed the fibril spacing of SPEG samples was more similar to fresh control than PBS. We concluded that swelling alters multiscale mechanics and damage in addition to tendon microstructure. Future mechanical testing should consider using SPEG as a bath solution with an osmotic pressure which preserves fresh tissue water content.

Angiotensin-converting Enzyme 2–containing Small Extracellular Vesicles and Exomeres Bind the Severe Acute Respiratory Syndrome Coronavirus 2 Spike Protein

Angiotensin-converting Enzyme 2–containing Small Extracellular Vesicles and Exomeres Bind the Severe Acute Respiratory Syndrome Coronavirus 2 Spike Protein

Inactivation of Escherichia coli K12 in phosphate buffer saline and orange juice by high hydrostatic pressure processing combined with freezing

Synergistic action of high hydrostatic pressure (HHP) and freezing on inactivation of Escherichia coli K12 in phosphate buffered saline (PBS) was investigated by employing response surface methodology. Samples containing E. coli were stored at 4, −24 and −80 °C overnight before they were pressurized. A maximum of 1.83 log reduction of CFU·ml−1 was obtained following a 9-min treatment at 400 MPa and 4 ± 1 °C in samples stored at 4 °C whereas, 5.63 and 6.83 log reductions were obtained in samples frozen at −24 and −80 °C, respectively. Major disruption of E. coli cells observed by scanning electron microscopy and increased amounts of DNA and RNA measured in pressure treated frozen PBS samples indicated that the main mechanism of inactivation in frozen samples was due to cell rapture. The validity of enhanced microbial inactivation by freezing before HHP for a real food system was tested by using orange juice. Pressurization (250 MPa, 15 min) of frozen (−80 °C) orange juice resulted in 4.88, 4.15 and 4.61 log CFU·ml−1 reductions in number of E. coli for the samples having pH 3.2, 4.5 and 5.8, respectively. In the absence of freezing, the same treatment caused only up to 0.42 log reduction in samples having pH 4.5 and 5.8.

Identification and Quantitative Determination of Lactate Using Optical Spectroscopy-Towards a Noninvasive Tool for Early Recognition of Sepsis.

Uninterrupted monitoring of serum lactate levels is a prerequisite in the critical care of patients prone to sepsis, cardiogenic shock, cardiac arrest, or severe lung disease. Yet there exists no device to continuously measure blood lactate in clinical practice. Optical spectroscopy together with multivariate analysis is proposed as a viable noninvasive tool for estimation of lactate in blood. As an initial step towards this goal, we inspected the plausibility of predicting the concentration of sodium lactate (NaLac) from the UV/visible, near-infrared (NIR), and mid-infrared (MIR) spectra of 37 isotonic phosphate-buffered saline (PBS) samples containing NaLac ranging from 0 to 20 mmol/L. UV/visible (300–800 nm) and NIR (800–2600 nm) spectra of PBS samples were collected using the PerkinElmer Lambda 1050 dual-beam spectrophotometer, while MIR (4000–500 cm−1) spectra were collected using the Spectrum two FTIR spectrometer. Absorption bands in the spectra of all three regions were identified and functional groups were assigned. The concentration of lactate in samples was predicted using the Partial Least-Squares (PLS) regression analysis and leave-one-out cross-validation. The regression analysis showed a correlation coefficient (R2) of 0.926, 0.977, and 0.992 for UV/visible, NIR, and MIR spectra, respectively, between the predicted and reference samples. The RMSECV of UV/visible, NIR, and MIR spectra was 1.59, 0.89, and 0.49 mmol/L, respectively. The results indicate that optical spectroscopy together with multivariate models can achieve a superior technique in assessing lactate concentrations.

Freeze-concentrated glass-like transition temperature of carbohydrate–phosphate buffered saline systems and impact on collapse of freeze-dried solids

Phosphate buffered saline (PBS) and carbohydrates are used to freeze-dried biomaterials. It has been suggested that PBS reduces the freeze-concentrated glass-like transition temperature ( $$T_{\text{g}}^{\prime }$$ ) of carbohydrate solutions and that freeze-dried solids collapse readily during freeze-drying. In order to obtain more insight into the subject, the effect of PBS on the $$T_{\text{g}}^{\prime }$$ of trehalose solution was systematically investigated. The $$T_{\text{g}}^{\prime }$$ of trehalose solution was found to be independent of the trehalose content. The $$T_{\text{g}}^{\prime }$$ of trehalose–PBS solution, on the other hand, decreased with decreasing trehalose content. The behavior was described as a $$T_{\text{g}}^{\prime }$$ curve for a trehalose–PBS pseudobinary system. The $$T_{\text{g}}^{\prime }$$ curve was analyzed using the modified Gordon–Taylor equation, and the $$T_{\text{g}}^{\prime }$$ of PBS was extrapolated to be 195.0 K. In order to compare the plasticizing effect of PBS, the $$T_{\text{g}}^{\prime }$$ values of other carbohydrate materials including sugar alcohols (glucose, maltitol, sucrose, inulin, and maltodextrin) were also investigated. It was found that freeze-concentrated trehalose was more sensitive to the plasticizing effect of PBS than the other sugars. Finally, trehalose and trehalose–PBS solutions with varying trehalose content were freeze-dried, and their water activity (aw) and apparent volume ratio against pre-dried (frozen) solids (VFD VF−1 ) were evaluated. Freeze-dried trehalose samples had low aw values and high VFD VF−1 values. Freeze-dried trehalose–PBS samples, on the other hand, had significantly higher aw values and lower VFD VF−1 values than freeze-dried trehalose samples depending on the trehalose content. These results corresponded to the $$T_{\text{g}}^{\prime }$$ and initial solute content.

In vitro quantification of lactate in Phosphate Buffer Saline (PBS) samples.

Continuous measurement of lactate levels in the blood is a prerequisite in intensive care patients who are susceptible to sepsis due to their suppressed immune system and increased metabolic demand. Currently, there exists no noninvasive tool for continuous measurement of lactate in clinical practice. The current mode of measurement is based on arterial blood gas analyzers which require sampling of arterial blood. In this work, we propose the use of Near Infra-Red (NIR) spectroscopy together with multivariate models as a means to non-invasively predict the concentration of lactate in the blood. As the first step towards this objective, we examined the possibility of accurately predicting concentrations of sodium lactate (NaLac) from the NIR spectra of 37 isotonic phosphate buffer saline (PBS) samples containing NaLac ranging from 0 to 20 mmol/L. NIR spectra of PBS samples were collected using the Lambda 1050 dual beam spectrometer over a spectral range of 800 - 2600 nm with a quartz cell of 1 mm optical path. Estimates and calibration of the lactate concentration with the NIR spectra were made using Partial Least-Squares (PLS) regression analysis and leave-one-out cross-validation on filtered spectra. The regression analysis showed a correlation coefficient of 0.977 and a standard error of 0.89 mmol/L between the predicted and prepared samples. The results suggest that NIR spectroscopy together with multivariate models can be a valuable tool for non-invasive assessment of blood lactate concentrations.

Modulating physical properties of porcine urethra with injection of novel biomimetic proteoglycans ex vivo.

Urinary incontinence is a significant challenge for women who are affected by it. We propose augmenting the tissue structure to restore normal biomechanics by molecularly engineering the tissue using a novel family of biomimetic proteoglycans (BPGs). This work examines the ability of BPGs to modulate the mechanical and physical properties of porcine urethras ex vivo to determine the feasibility of BPGs to be implemented as molecular treatment for stress urinary incontinence (SUI). We investigated compliance by performing a unique radial expansion testing method using urethras from six- to nine-month-old pigs. The urethras were injected with 0.5 ml BPG solution at three sites every approximately 120° (conc.: 25 mg ml-1, 50 mg ml-1 and 75 mg ml-1 in 1× phosphate-buffered saline (PBS); n = 4 per group) and compared them with PBS-injected controls. Young's modulus was calculated by treating the urethra as a thin-walled pressure vessel. A water uptake study was performed by soaking 10 mm urethra biopsy samples that were injected with 0.1 ml BPG solution (conc.: 50 mg ml-1, 100 mg ml-1 and 200 mg ml-1 in 1× PBS; n = 6 per group) in 5 ml PBS for 24 h. Although there was no significant difference in Young's modulus data, there were differences between groups as can be seen in the raw radial expansion testing data. Results showed that BPGs have the potential to increase hydration in samples, and that there was a significant difference in water uptake between BPG-injected samples and the controls (100 mg ml-1 samples versus PBS samples, p < 0.05). This work shows that BPGs have the potential to be implemented as a molecular treatment for SUI, by restoring the diminished proteoglycan content and subsequently increasing hydration and improving the compliance of urethral tissue.

Highly Sensitive and Reliable Electrospun Polyaniline Nanofiber Based Biosensor as a Robust Platform for COX-2 Enzyme Detections

Highly sensitive, reliable and practical detection of Cyclooxygenase-2 (COX-2) as an important enzyme in pain biomarkers, inflammation, and cancer cell proliferation is of great importance. This study demonstrates the feasibility of developing nanobiosensor (or biosensor) platforms for sensitive COX-2 biomarker detection from phosphate buffer saline (PBS) and human serum samples. Highly porous polyaniline nanofibers were fabricated in four different average diameters using electrospinning process. They were then integrated as the main sensing component into interdigitated gold microelectrodes to develop label-free electrochemical nanobiosensors. The performance of the nanobiosensors was evaluated in comparison with a plain control biosensor using electrochemical impedance spectroscopy (EIS). Significant improvement was observed in the sensitivity of the nanofiber-based biosensors revealing the remarkable capability of electrospun polyaniline nanofiber in robust and rapid detection of the COX-2 biomarker. The fabricated nanofiber-based biosensors were able to detect the target antigen with concentrations as low as 0.01 pg/ml in PBS and human serum samples, respectively. High sensitivity, as well as remarkable selectivity towards COX-2 analyte, suggested the excellent potential of this nanofiber-based platform for reliable COX-2 analyte detection.

Controlled in vitro degradation behavior of highly oriented long-chain-branched poly(lactic acid) produced by solid-phase die drawing.

Highly oriented long-chain-branched poly(lactic acid) (LCB-PLA) was fabricated through solid-phase die drawing technology, and the in vitro degradation behavior of the oriented samples in phosphate-buffered saline (PBS) was studied. During degradation, the weight retention and molecular weight for both PLA and LCB-PLA increased with the increase of draw ratio. Moreover, the degradation autocatalytic effect was delayed, and the deterioration of mechanical strength was reduced by orientation, which was beneficial for controlling the degradation degree and decay rate of strength for PLA as bone fixation materials. The influence mechanism of orientation on the in vitro degradation of PLA was explored. The degradation of PLA in PBS was ascribed to the hydrolytic degradation of ester bonds on the molecular chain. By orientation, a dense microfibrillar crystalline structure formed both on the surface and inside of PLA samples, limiting the diffusion and absorption of PBS molecules into the PLA matrix effectively, inhibiting the hydrolytic degradation of ester bonds, and thus delaying the deterioration of mechanical properties of PLA. © 2019 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2019.

Towards the Implementation of a Wirelessly Powered Dielectric Sensor With Digitized Output for Implantable Applications

This article proposes a wirelessly powered dielectric sensor for industrial and medical applications. The sensor includes a 5-bit binary-weighted capacitor bank and an energy-harvesting rectifier realized as an integrated circuit (IC). With an automated algorithm, the capacitor bank is adjusted to counterbalance the influence of the dielectric material under test. The digitized values of the capacitor bank offer a quantitative measurement of the dielectric constant. The IC was fabricated in 180-nm CMOS process, and the control algorithm was implemented in a discrete microcontroller. The rectifier adopts a differentially cross-connected topology which achieves the rectification efficiency around 72%–82%. The proposed system is used to measure the volume of phosphate-buffered saline (PBS), in which the sensor is placed under the petri dish with PBS samples. This work shows promise for implantable applications such as bladder urine monitoring and other body fluid analysis.