Sorption Characteristics and Chromatographic Separation of 90Y3+ from 90Sr2+ from Aqueous Media by Chelex-100 (Anion Ion Exchange) Packed Column.

There is growing demand for separation of 90Y carrier free from 90Sr coexisting to produce high purity 90Y essential for radiopharmaceutical uses. Thus, in this context the sorption profiles of Y3+ and Sr2+ from aqueous solutions containing diethylenetriaminepenta acetic acid (DTPA), ethylenediaminetetra-acetic acid (EDTA), acetic acid, citric acid, or NaCl onto Chelex-100 (anion ion exchange) solid sorbent were critically studied for developing an efficient and low-cost methodology for selective separation of Y3+ from Sr2+ ions (1.0 × 10-5 M). Batch experiments displayed relative chemical extraction percentage (98 ± 5.4%) of Y3+ from aqueous acetic acid solution onto Chelex-100 (anion ion exchanger), whereas Sr2+ species showed no sorption. Hence, a selective separation of Y3+ from its parent 90Sr2+ has been established based upon percolation of the aqueous solution of Y3+ and Sr2+ ions containing acetic acid at pH 1-2 through Chelex-100 sorbent packed column at a 2 mL min-1 flow rate. Y3+ species were retained quantitatively while Sr2+ ions were not sorbed and passed through the sorbent packed column without extraction. The sorbed Y3+ species were then recovered from the sorbent packed column with HNO3 (1.0 M) at a 1.0 mL min-1 flow rate. A dual extraction mechanism comprising absorption associated to "weak-base anion exchanger" and "solvent extraction" of Y3+ as (YCl6)3- and an extra part for "surface adsorption" of Y3+ by the sorbent is proposed. The established method was validated by measuring the radiochemical (99.2 ± 2 1%), radionuclide purity and retardation factor (Rf = 10.0 ± 0.1 cm) of 90Y3+ recovered in the eluate. Ultimately, the sorbent packed column also presented high stability for reusing 2-3 cycles without drop in its efficiency (±5%) towards Y3+ uptake and relative chemical recovery. A proposed flow sheet describing the analytical procedures for the separation of 90Y3+ from 90Sr2+ using chelating Chelex 100 (anion exchange) packed column is also included.

Sol-Gel Functionalized Polyurethane Foam-Packed Mini-Column as an Efficient Solid Extractor for the Rapid and Ultra-Trace Detection of Textile Dyes in Water.

Textile dyes widely used in industrial products are known as a major threat to human health and water ecological security. On the other hand, sol gel represents a principal driver of the adoption of dispersive solid-phase microextractors (d-µ SPME) for pollutants residues in water. Thus, the current study reports a new and highly rapid and highly efficient hybrid sol-gel-based sponge polyurethane foam as a dispersive solid-phase microextractor (d-µ-SPME) platform packed mini-column for complete preconcentration and subsequent spectrophotometric detection of eosin Y textile dye in wastewater. The unique porous structure of the prepared sol-gel immobilized polyurethane foams (sol-gel/PUF) has suggested its use for the complete removal of eosin Y dye (EY) from water. In the mini-column, the number (N) of plates, the height equivalent to the theoretical plates (HETP), the critical capacity (CC), and the breakthrough capacities (BC) of the hybrid sol-gel-treated polyurethane foams towards EY dye were determined via the breakthrough capacity curve at various flow rates. Under the optimum condition using the matrix match strategy, the linear range of 0.01-5 µg L-1, LODs and LOQs in the range of 0.006 µg L-1, and 0.01 µg L-1 for wastewater were achieved. The intra-day and inter-day precisions were evaluated at two different concentration levels (0.05 and 5 µg L-1 of dye) on the same day and five distinct days, respectively. The analytical utility of the absorbents packed in pulses and mini-columns to extract and recover EY dye was attained by 98.94%. The column could efficiently remove different dyes from real industrial effluents, and hence the sol-gel/PUF is a good competitor for commercial applications. The findings of this research work have strong potential in the future to be used in selecting the most suitable lightweight growing medium for a green roof based on stakeholder requirements. Therefore, this study has provided a convenient pathway for the preparation of compressible and reusable sponge materials from renewable biomass for efficient removal of EY from the water environment.

An Eco-Friendly, Interference, and Solvent Free Surfactant-Assisted Dual-Wavelength ß-CorrectionSpectrometric Method for Total Determination and Speciation of Cu2+ Ions in Water.

Spectral interference through the presence of uninformative variables, excess reagents, and complications in the refinement of the analyte signal is common in the quest to identify complex species in real samples. Therefore, an economical green, facile, and sensitive strategy has been developed for Cu2+ detection using the anionic surfactant sodium dodecylsulphate- (SDS-) assisted dual-wavelength ß-correction spectrophotometric strategy combined with the chromogenic reagent zincon (ZI). The low limits of detection (LOD) and quantification (LOQ) of Cu2+ using ordinary (single wavelength) spectrophotometry were 0.19 (3.02) and 0.63 (10.0) µgmL-1, and these values were improved to 0.08 (1.27) and 0.26 µgmL-1 (4.12 µM)) using ß-correction (dual wavelength) spectrophotometry, respectively. The LOD and LOQ were improved from 0.08 (1.27) and 0.26 (4.12) µgmL-1 to 0.02 (0.32) and 0.08 µgmL-1 (1.27 µM) using SDS-assisted dual-ß-correction spectrometry, respectively. Ringbom, s, and the corrected absorbance (Ac) versus Cu2+ concentration plots were linear over the concentration range 1.10-2.4 (17.4-38.1) and 0.50-2.40 µgmL-1 (7.94-38.1 µM), respectively. Sandell's sensitivity index of 3.0 × 10-3 µg/cm2 was achieved. The selectivity was further confirmed via monitoring the impact of common diverse ions and surfactants on the corrected absorbance. Total determination and Cu2+ speciation in water were favorably implemented and validated by ICP-OES at 95% (P=0.05). Satisfactory Cu2+ recoveries in tap (92.2-98.0%) and mineral (105-111.0%) water samples were achieved. The sensing system is simple, reliable, sensitive, and selective for Cu2+ detection.

Phthalate esters and plastic debris abundance in the Red Sea and Sharm Obhur and their ecological risk level.

The abundance of plastic debris (PDs) and its correlation with phthalic acid esters (PAEs), a class of pollutants associated with plastics, is not well understood, although PDs have been reported in relation to the release and distribution of aquatic pollutants such as PAEs. Few studies have linked the distribution of these pollutants in seawater. The current study examined the abundance and relationship of PDs and PAEs in seawater from Sharm Obhur and the Red Sea. Estimates were also made of their ecological impacts. Sharm Obhur is a semi-enclosed bay on the eastern shore of the Red Sea, near Jeddah, Saudi Arabia, and is heavily impacted by human activities. Contaminants from Sharm Obhur may be transported into the deep waters of the Red Sea by the subsurface outflow. The PAEs concentrations in the study area ranged from 0.8 to 1224 ng/L. Among the six PAEs studied, diethyl phthalate (DEP) (22-1124 ng/L), di-n-butyl phthalate (DBP) (9-346 ng/L) and di (2-ethylhexyl) phthalate (DEHP) (62-640 ng/L) were the predominant additives detected across all the sampling sits. Whereas the other PAEs, dimethyl phthalate (DMP) (5-76 ng/L), benzyl butyl phthalate (BBP) (4-25 ng/L) and di-n-octyl phthalate DnOp (0.5-80 ng/L) were generally lower in most samples. The sum of the six analyzed PAEs (∑6 PAEs) was lower at Sharm Obhur (587 ± 82 ng/L) and in the Red Sea shelf (677 ± 182 ng/L) compared to the Red Sea shelf break (1266 ± 354 ng/L). This suggests that degradation and adsorption of PAEs were higher in Sharm Obhur and on the shelf than on the shelf break. In contrast, there was no difference in the abundance of PDs between Sharm Obhur (0.04 ± 0.02 PDs/m3), Red Sea shelf (0.05 ± 0.02 PDs/m3) and in the Red Sea shelf break (0.03 ± 0.1 PDs/m3). Polyethylene (32%) and polypropylene (8%) were dominant, mostly smaller than 5 mm2 (78%), with the majority consisting of white (52%) and black (24%) fragments (39%), fibers (35%) and films (24%). A positive correlation between PAE concentration and abundance of PDs, suggests either a common source or a causal link through leaching. The ecological risk of ∑4PAEs (DMP, DEP, DBP and DEHP) ranged from (0.20-0.78), indicating a low to moderate risk for the Red Sea. The pollution index of PDs ranged from (0.14-0.36), showing that the Sharm Obhur and both sites of Red Sea suffered relatively low pollution.

Novel nandrolone aptamer for rapid colorimetric detection of anabolic steroids.

The illicit use of anabolic androgenic steroids (AAS) as performance-enhancing drugs remains a global issue threatening not only the credibility of competitive sports but also public health due to the well-documented adverse effects they elicit. AAS abuse is not restricted only to professional sports, but also extends to recreational athletes and adolescents as well as in livestock production as growth-promoting agents. Testosterone and nandrolone are among the AAS most frequently exploited. Gas chromatography-mass spectrometry is the reference method for AAS detection, but it is strictly laboratory-based and cannot be performed on-site. The great potential of aptamers in bioanalytical applications and specifically for the development of simple analytical tools suitable for on-site analysis has been extensively documented. In this report, we describe the selection and identification of aptamers binding nandrolone, exhibiting affinity dissociation constants in the low nanomolar range. A label-free colorimetric assay based on gold nanoparticles was developed using one of these novel aptamers for the detection of nandrolone and/or its metabolites. The assay could be deployed for the rapid, on-site, facile and cost-effective screening of samples and provide qualitative visual results with a red to purple/blue color change being indicative of a positive result.

The effects of salinity, temperature, and UV irradiation on leaching and adsorption of phthalate esters from polyethylene in seawater.

In this study, the leaching of six phthalic acid esters (PAEs) from three common consumer plastics was investigated: low and high density polyethylene (LDPE, HDPE) and recycled polyethylene (RP). The effects of salinity, temperature, and ultraviolet irradiation (UVR) on leaching were investigated. The study of leaching of phthalates in aqueous environments in batch experiments is challenging due to their readsorption by the high hydrophobicity of PAEs, and there are no standard methods to study release processes. Here with the experiments, leaching (A) and spiking (B) using six PAEs to study the readsorption in the leaching process. PAEs were identified and quantified using GC-MS. Dibutyl phthalate (DBP) and benzyl butyl phthalate (DEHP) showed considerable leaching during the 5-day incubation: 14 ±â€¯1 to 128 ±â€¯14 and 25 ±â€¯2 to 79 ±â€¯5 ng/cm2, respectively, under UVR, corresponding approximately to (1.9-13%) and (12.4-22.4%) of the solvent extracted mass. The highest Kd values were measured for RP polymers (0.3-9.4), followed by LDPE (0.5-5.4) and HDPE (0.2-2.2) polymers. Thus, readsorption of PAEs at the surface removed 30-80% of the leached PAEs in the dissolved phase. For example in LDPE, the calculated total release of DBP was up to 54 ±â€¯4 ng/cm2, while the dissolved amount was 8.5 ±â€¯1 ng/cm2 during the 5-day incubation under freshwater conditions. Increasing salinity negatively affected the leaching rate, which decreased for DBP from 54 ±â€¯4 ng/cm2 in freshwater to 44 ±â€¯3 and 38 ±â€¯3 ng/cm2 at salinity of 20 and 40 g/L, respectively, from LDPE during the 5-day incubation. Temperature and UVR had a positive effect on the leaching rate, with the release of DBP from LDPE increasing from 44 ±â€¯3 ng/cm2 at room temperature (25 °C) to 60 ±â€¯6 and 128 ±â€¯14 ng/cm2 at high temperature (40 °C) and UVR, respectively. Overall, this study highlights the positive relationship between temperatures, UVR on the extent of leaching and surface adsorption on the leaching measurements.

A Highly Sensitive Modified Glassy Carbon Electrode with a Carboxylated Multi-walled Carbon Nanotubes/Nafion Nano Composite for Voltammetric Sensing of Dianabol in Biological Fluid.

The extraordinary prerequisite for the analysis of an anabolic steroid, namely dianabol (DB), has inspired towards the development of a cost-effective and high-performance sensing probe. Thus, a simple and robust electrochemical sensor (c-MWCNTs-Nafion®lGCE) for dianabol (DB), a widely used steroid, was developed using a glassy carbon electrode (GCE) modified with functionalized carboxylated multi-walled carbon nanotubes (c-MWCNT) and Nafion®. At pH 7 - 8, differential pulse-cathodic stripping voltammetry (DP-CSV) displayed two cathodic peaks at -0.85 and -1.35 V that varied linearly over a wide range (9.0 × 10-9 (2.7 µg L-1) - 9.0 × 10-6 (2.7 × 103 µg L-1) mol L-1) and 2.9 × 10-6 (8.7 × 102 µg L-1) - 8.0 × 10-5 (2.4 × 104 µg L-1) mol L-1) of DB concentrations, respectively. The low limits of detection and quantification at peak I (-0.85 V) were 2.7 × 10-9 (8.1 × 10-1 ng mL-1) and 9.0 × 10-9 (2.7 ng mL-1) mol L-1, respectively. The repeatability and reproducibility displayed relative standard deviations lower than 5%. The method was applied for DB analysis in human urine and subsequently compared with the standard HPLC method. Interference of common metabolites in biological fluids samples to DB sensing was insignificant. This method has distinctive advantages e.g. precise, short analytical time, sensitive, economical, reproducible and miniaturized sample preparation for DB analysis in biological samples of human origin.

Gold nanoparticle aptamer assay for the determination of histamine in foodstuffs.

The development of a gold nanoparticle aptamer assay is persued for rapid and sensitive determination of histamine in foodstuffs, which could be deployed for on-site use. The assay is based on a histamine-specific aptamer and gold nanoparticles and the salt-induced aggregation of the particles in the presence of histamine indicated by the color change from red to blue. Gold nanoparticle size, salt type, and concentration as well as aptamer concentration were optimized, and using optimum conditions, a limit of detection of 8 nM (~ 0.05 mg/kg) was obtained. Finally, the aptamer AuNP assay was applied to the determination of histamine in quality control fish samples. The histamine levels of these samples had previously been determined using HPLC and commercial ELISA kits by numerous independent laboratories and a good correlation was obtained. The developed AuNP assay is rapid, sensitive, and reproducible. Graphical abstract.

Yersinia pestis detection using biotinylated dNTPs for signal enhancement in lateral flow assays.

Due to the extreme infectivity of Yersinia pestis it poses a serious threat as a potential biowarfare agent, which can be rapidly and facilely disseminated. A cost-effective and specific method for its rapid detection at extremely low levels is required, in order to facilitate a timely intervention for containment. Here, we report an ultrasensitive method exploiting a combination of isothermal nucleic acid amplification with a tailed forward primer and biotinylated dNTPs, which is performed in less than 30 min. The polymerase chain reaction (PCR) and enzyme linked oligonucleotide assay (ELONA) were used to optimise assay parameters for implementation on the LFA, and achieved detection limits of 45 pM and 940 fM using SA-HRP and SA-polyHRP, respectively. Replacing PCR with isothermal amplification, namely recombinase polymerase amplification, similar signals were obtained (314 fM), with just 15 min of amplification. The lateral flow detection of the isothermally amplified and labelled amplicon was then explored and detection limits of 7 fM and 0.63 fg achieved for synthetic and genomic DNA, respectively. The incorporation of biotinylated dNTPs and their exploitation for the ultrasensitive molecular detection of a nucleic acid target has been demonstrated and this generic platform can be exploited for a multitude of diverse real life applications.

Pediatric glioblastoma target-specific efficient delivery of gemcitabine across the blood-brain barrier via carbon nitride dots.

Pediatric glioblastomas are known to be one of the most dangerous and life-threatening cancers among many others regardless of the low number of cases reported. The major obstacles in the treatment of these tumors can be identified as the lack of prognosis data and the therapeutic requirement to be able to cross the blood-brain barrier (BBB). Due to this lack of data and techniques, pediatric patients could face drastic side effects over a long-time span even after survival. Therefore, in this study, the capability of non-toxic carbon nitride dots (CNDs) to selectively target pediatric glioblastoma cells was studied in vitro. Furthermore, the nanocarrier capability and efficiency of CNDs were also investigated through conjugation of a chemotherapeutic agent and transferrin (Tf) protein. Gemcitabine (GM) was introduced into the system as a chemotherapeutic agent, which has never been successfully used for the treatment of any central nervous system (CNS) cancer. More than 95% of selective damage of SJGBM2 glioma cells was observed at 1 µM of CN-GM conjugate with almost 100% viability of non-cancerous HEK293 cells, although this ability was diminished at lower concentrations. However, further conjugation of Tf to obtain CN-GM-Tf allowed the achievement of selective targeting and prominent anti-cancer activity at a 100-fold lower concentration of 10 nM. Furthermore, both conjugates were capable of effectively damaging several other brain tumor cells, which were not well responsive towards the single treatment of GM. The capability of BBB penetration of the conjugates was observed using a zebrafish model, which confirms the CNDs' competence as an excellent nanocarrier to the CNS.

Tyrosinase enzyme Langmuir monolayer: Surface chemistry and spectroscopic study.

This study investigates the surface chemistry properties of the tyrosinase enzyme Langmuir monolayer at air-aqueous interface using sodium chloride in the subphase to induce the surface activity of the enzyme. Investigation of surface packing and stability of the tyrosinase Langmuir monolayer were performed using surface chemistry experiments while spectroscopic analysis was done to study enzyme conformation. It was found that the tyrosinase enzyme forms a fluid film at air-aqueous interface with good stability as shown by compression-decompression cycles experiments and stability measurements at various surface pressures. UV-vis absorption and fluorescence measurements at different surface pressures revealed that the Langmuir monolayer has good homogeneity with no evidence of aggregates during compression. To gain insight on the conformation of tyrosinase Langmuir monolayer p-polarized infrared-reflection absorption spectroscopy was used. It was found that at high surface pressures the predominant secondary structures were ß-sheets while at lower surface pressure both α -helices and ß-sheets were present. The circular dichroism spectra were obtained by transferring the Langmuir monolayer at 10 mN.m-1 to a solid quartz support (Langmuir-Blodgett film, LB film), which showed that the major conformation present were α-helices. Images from the immobilized LB films were obtained using atomic force microscopy which showed homogenous and regular deposition with a mean thickness ranging from 3 to 4 nm.

One-Pot SELEX: Identification of Specific Aptamers against Diverse Steroid Targets in One Selection.

Aptamers are well-established biorecognition molecules used in a wide variety of applications for the detection of their respective targets. However, individual SELEX processes typically performed for the identification of aptamers for each target can be quite time-consuming, labor-intensive, and costly. An alternative strategy is proposed herein for the simultaneous identification of different aptamers binding distinct but structurally similar targets in one single selection. This one-pot SELEX approach, using the steroids estradiol, progesterone, and testosterone as model targets, was achieved by combining the benefits of counter-SELEX with the power of next-generation sequencing and bioinformatics analysis. The pools from the last stage of the selection were compared in order to discover sequences with preferential abundance in only one of the pools. This led to the identification of aptamer candidates with potential specificity to a single steroid target. Binding studies demonstrated the high affinity of each selected aptamer for its respective target, and low nanomolar range dissociation constants calculated were similar to those previously reported for steroid-binding aptamers selected using traditional SELEX approaches. Finally, the selected aptamers were exploited in microtiter plate assays, achieving nanomolar limits of detection, while the specificity of these aptamers was also demonstrated. Overall, the one-pot SELEX strategy led to the discovery of aptamers for three different steroid targets in one single selection without compromising their affinity or specificity, demonstrating the power of this approach of aptamer discovery for the simultaneous selection of aptamers against multiple targets.

Nontoxic amphiphilic carbon dots as promising drug nanocarriers across the blood-brain barrier and inhibitors of ß-amyloid.

The blood-brain barrier (BBB) is a main obstacle for drug delivery targeting the central nervous system (CNS) and treating Alzheimer's disease (AD). In order to enhance the efficiency of drug delivery without harming the BBB integrity, nanoparticle-mediated drug delivery has become a popular therapeutic strategy. Carbon dots (CDs) are one of the most promising and novel nanocarriers. In this study, amphiphilic yellow-emissive CDs (Y-CDs) were synthesized with an ultrasonication-mediated methodology using citric acid and o-phenylenediamine with a size of 3 nm that emit an excitation-independent yellow photoluminescence (PL). The content of primary amine and carboxyl groups on CDs was measured as 6.12 × 10-5 and 8.13 × 10-3 mmol mg-1, respectively, indicating the potential for small-molecule drug loading through bioconjugation. Confocal image analyses revealed that Y-CDs crossed the BBB of 5-day old wild-type zebrafish, most probably by passive diffusion due to the amphiphilicity of Y-CDs. And the amphiphilicity and BBB penetration ability didn't change when Y-CDs were coated with different hydrophilic molecules. Furthermore, Y-CDs were observed to enter cells to inhibit the overexpression of human amyloid precursor protein (APP) and ß-amyloid (Aß) which is a major factor responsible for AD pathology. Therefore, data suggest that Y-CDs have a great potential as nontoxic nanocarriers for drug delivery towards the CNS as well as a promising inhibiting agent of Aß-related pathology of the AD.

High Affinity Aptamer for the Detection of the Biogenic Amine Histamine.

The importance of histamine in various physiological functions and its involvement in allergenic responses make this small molecule one of the most studied biogenic amines. Even though a variety of chromatography-based methods have been described for its analytical determination, the disadvantages they present in terms of cost, analysis time, and low portability limit their suitability for in situ routine testing. In this work, we sought to identify histamine-binding aptamers that could then be exploited for the development of rapid, facile, and sensitive assays for histamine detection suitable for point-of-need analysis. A classic SELEX process was designed employing magnetic beads for target immobilization and the selection was completed after ten rounds. Following Next Generation Sequencing of the last selection rounds from both positive and counter selection magnetic beads, several sequences were identified and initially screened using an apta-PCR affinity assay (APAA). Structural and functional characterization of the candidates resulted in the identification of the H2 aptamer. The high binding affinity of the H2 aptamer to histamine was validated using four independent assays ( KD of 3-34 nM). Finally, the H2 aptamer was used for the development of a magnetic beads-based competitive assay for the detection of histamine in both buffer and synthetic urine, achieving very low limits of detection of 18 pM and 76 pM, respectively, while no matrix effects were observed. These results highlight the suitability of the strategy followed for identifying small molecule-binding aptamers and the compatibility of the selected H2 aptamer with the analysis of biological samples, thus facilitating the development of point-of-care devices for routine testing. Ongoing work is focused on extending the application of the H2 aptamer to the detection of spoilage in meat, fish, and beverages, as well as evaluating the affinity of truncated forms of the aptamer.

Duplex PCR-ELONA for the detection of pork adulteration in meat products.

In this work, a duplex PCR-Enzyme Linked Oligonucleotide Assay (ELONA) is reported for the sensitive and reliable detection of pork adulteration in beef and chicken products, two of the most widely consumed meat types in the world. The strategy relies on the use of species-specific tailed primers for duplex amplification and simple dilution of the PCR reactions for direct colorimetric detection via hybridization, eliminating the need for any other post-amplification steps. A high sensitivity was achieved, with as low as 71-188 pg of genomic DNA able to be detected using mixtures of control DNA from each species. The strategy was validated using DNA add-mixtures as well as DNA extracted from raw meat mixtures and 0.5-1% w/w pork could be easily detected when mixed with beef or chicken. The proposed approach is simple, sensitive and cost-effective compared to equivalent commercial kits suitable for detecting adulterant pork levels in meat products.

An Ultrasensitive Detection Platform for Mercury Ions Speciation in Water Using Procaine Hydrochloride Ion Pair Coupled Extractive Spectrofluorimetry.

A simple extractive spectrofluorimetric strategy for trace determination of mercury(II) ions in water employing procaine hydrochloride (PQ+) as an ion pairing fluorescent tagging reagent has been established. The method was based upon the extraction of PQ+ from aqueous iodide media onto dichloromethane as a ternary complex ion associate [(PQ+)2.(HgI4)2-] at pH 9.0-10.0 with subsequent quenching at λex/em = 268/333 nm. The developed strategy exhibited a linear range 20-140 nM with a lower limit of detection (LOD) 6.1 nM, respectively. Intra and inter-day laboratory accuracy and precision for trace analysis of mercury(II) ions in water were performed. Complexed mercury(II) species in real water samples were evaluated along with chemical speciation and successful comparison with most of the reported methods. The method was validated by standard inductively coupled plasma-optical emission spectrometry (ICP-OES) method in terms of student's t- and F tests at 95% confidence interval. The method offers rapidity, selectivity, cost-effectiveness, robustness, and ruggedness. Graphical Abstract Schematic illustration of the proposed sensing mechanism for mercury(II).

Carbon dots and gold nanoparticles based immunoassay for detection of alpha-L-fucosidase.

Hepatocellular carcinoma (HCC) is among the leading causes of mortality in the world. The detection of HCC in its early stage is the key for early treatment and thus the improvement of the chances of survival. Among the various methods of HCC screening, assays based on the detection of biomarker that is specific to HCC such as alpha-l-fucosidase (AFU) have been regarded as the most prominent methods. In this regards, a new assay for the detection of AFU to screen HCC was developed. This assay was based on the energy transfer between carbon dots (C-dots) and gold nanoparticles (AuNPs), the concentration of AFU could be monitored by the degree of C-dots fluorescence quenching due to the energy transfer. With this assay, a limit of detection of 3.4 nM (well below the diagnostic cutoff point of 80 nM), and a broad linear range of detection from 11.3 to 200 nM were achieved. We also demonstrate the determination of the concentration of AFU in human blood serum.

Duplex Lateral Flow Assay for the Simultaneous Detection of Yersinia pestis and Francisella tularensis.

High-risk pathogens such as Francisella tularensis and Yersinia pestis are categorized as highly hazardous organisms that can be used as biological weapons. Given the extreme infectivity of these potential biowarfare agents, a rapid, sensitive, cost-effective, and specific method for their detection is required. Here, we report the multiplexed amplification detection of genomic DNA from Francisella tularensis and Yersinia pestis. Amplification was achieved using isothermal recombinase polymerase amplification, exploiting tailed primers, followed by detection using a nucleic-acid lateral flow assay. Excess primers were removed using a novel fishing strategy, avoiding the use of postamplification purification that requires centrifugation and infers additional assay cost. The entire assay is completed in less than 1 h, achieving limits of detection of 243 fg (1.21 × 102 genome equivalent) and 4 fg (0.85 genome equivalent) for Francisella tularensis and Yersinia pestis, respectively.

Effect of polymer coating composition on the aggregation rates of Ag nanoparticles in NaCl solutions and seawaters.

The aggregation behaviour of polymer-coated silver nanoparticles (AgNPs) was characterized in NaCl solutions, and in two seawaters of different salinities and dissolved organic matter (DOM) contents. Representative organic coatings i.e. tannic acid (TA), alginic acid (ALG), two gum Arabic samples (GAL and GAH), branched polyethylenimine (BPEI), and non-ionic surfactants (reference material NM-300K) were selected to cover a wide range of zeta-potentials. The stability in NaCl solutions, as determined from the rate of variation in hydrodynamic size within a timeframe of one hour, followed the order BPEI≫NM-300K≈GAL≫ALG≈TA≫GAH. In the seawater samples the order was NM-300K≈GAL≫ALG>GAH>TA≈BPEI, and only TA, GAL and NM-300K batches behaved as expected from the NaCl experiments. Remarkably, the BPEI sample showed the largest aggregation rate in the seawater sample with the highest DOM concentration (277µM C). The GAH sample displayed a non-monotonic variation in aggregation rate with NaCl concentration, apparently due to concomitant precipitation of AgCl. The results indicate that non-electrostatic stabilization mechanisms and DOM-coating interactions are important for the prediction of stability and persistence of polymer-coated AgNPs in seawater.

Quantification of Nucleic Acid Concentration in the Nanoparticle or Polymer Conjugates Using Circular Dichroism Spectroscopy.

The interface of nucleic acids and nanomaterials is among the most promising fields in recent years. Considerable efforts have been devoted to the development of novel systems based on the two components for various promising applications such as sensing, bioimaging, drug delivery, and theranostics. However, the determination of nucleic acid concentration in these systems remains as a challenge due to the interference of nanoparticles. To this end, we developed a simple, yet reliable, method to quantify the nucleic acid concentration in their nanoparticle or polymer conjugates based on circular dichroism (CD) spectroscopy. In this paper, three nucleic acids, namely, DNA sodium salt from calf thymus (NaDNA), DNA from herring sperm (hsDNA), and ribonucleic acid from torula yeast (tyRNA), were noncovalently conjugated to three nanoparticles. The concentrations of the three nucleic acids in their nanoparticle conjugates were successfully determined on the basis of CD spectra calibration curves.