Mobile genetic elements carrying aminoglycoside resistance genes in Acinetobacter baumannii isolates belonging to global clone 2.

Aminoglycosides are used to treat infections caused by carbapenem-resistant Acinetobacter baumannii (CRAB) strains. However, resistance to aminoglycosides has increased remarkably in the last few years. Here, we aimed to determine the mobile genetic elements (MGEs) associated with resistance to aminoglycosides in the global clone 2 (GC2) A. baumannii. Among the 315 A. baumannii isolates, 97 isolates were identified as GC2, and 52 of GC2 isolates (53.6%) were resistant to all the aminoglycosides tested. The AbGRI3s carrying armA were detected in 88 GC2 isolates (90.7%), and of them, 17 isolates (19.3%) carried a new variant of AbGRI3 (AbGRI3ABI221). aphA6 was located in TnaphA6 of 30 isolates out of 55 aphA6-harboring isolates, and 20 isolates were found to harbor TnaphA6 on a RepAci6 plasmid. Tn6020 carrying aphA1b was detected in 51 isolates (52.5%), which was located within AbGRI2 resistance islands. The pRAY* carrying the aadB gene was detected in 43 isolates (44.3%), and no isolate was found to contain a class 1 integron harboring this gene. The GC2 A. baumannii isolates contained at least one MGE carrying the aminoglycoside resistance gene, located mostly either in the chromosome within AbGRIs or on the plasmids. Thus, it is likely that these MGEs play a role in the dissemination of aminoglycoside resistance genes in GC2 isolates from Iran.

Chitosan/luminol/AgNPs nanocomposite for electrochemiluminescent determination of prostate-specific antigen.

A green, environmentally friendly protocol was developed for ultrasensitive and highly specific recognition of prostate-specific antigen (PSA) based on the ECL effect of luminol supported by chitosan-silver nanoparticles (CS/AgNPs) nanocomposites. The transducing surface was fabricated through two consecutive electrodeposition steps of gold nanoparticles (AuNPs) and chitosan (CS)-AgNPs-luminol electrochemiluminophore onto the glassy carbon electrode. In addition to an appropriate desirable biocompatibility, the electrochemical synthesis presents low-cost preparation and ultrafast determination opportunity. AgNPs play a linking role to attach luminol, as an ECL agent to the CS support via donor-acceptor bonds between Ag atoms with NH groups of luminol and CS. Also, AgNPs can amplify the ECL intensity as a consequence of their excellent specific surface area and conductivity. To enhance the performance of the nanobiosensor, AuNPs were also used due to their high-specific surface area and excellent affinity toward amine groups of CS. Based on this high-performance analysis strategy, ultrasensitive screening of PSA was attained with a desirable limit of detection of 0.6 ng mL-1 and a broad linear range between 1 pg mL-1 and 10 ng⋅mL-1 (R2=0.994). Approximately, the same results were recorded for the analysis of the unprocessed serum samples of patients with prostate cancer at different stages. This research provided significant insight into electrografting methods to construct ECL transducers for clinical monitoring of PSA and other tumor biomarkers in the clinical setting.

Electrochemical biosensors in exosome analysis; a short journey to the present and future trends in early-stage evaluation of cancers.

The tumor microenvironment consists of a multiplicity of cells such as cancer cells, fibroblasts, endothelial cells, and immune cells within the specific parenchyma. It has been indicated that cancer cells can educate other cells within the tumor niche in a paracrine manner by the release of nano-sized extracellular vesicles namely exosomes (Exo), resulting in accelerated tumor mass growth. It is suggested that exosomal cargo with remarkable information can reflect any changes in metabolic and proteomic profiles in parent tumor cells. Therefore, exosomes can be touted as prognostic, diagnostic, and therapeutic elements with specific biomarkers in patients with different tumor types. Despite the advantages, conventional exosome separation and purification protocols are time-consuming and laborious with low abnormal morphology and purity rate. During the last decades, biosensor-based modalities, as emerging instruments, have been used to detect and analyze Exo in biofluids. Due to suitable specificity, sensitivity, and real-time readout, biosensors became promising approaches for the analysis of Exo in in vitro and in vivo settings. The inherent advantages and superiority of electrochemical biosensors in the determination of tumor grade based on exosomal cargo and profile were also debated. Present and future challenges were also discussed related to the application of electrochemical biosensors in the clinical setting. In this review, the early detection of several cancer types associated with ovaries, breast, brain, colon, lungs, T and B lymphocytes, liver and rare types of cancers were debated in association with released exosomes.

Nanotechnology-based electrochemical biosensors for monitoring breast cancer biomarkers.

Breast cancer is categorized as the most widespread cancer type among women globally. On-time diagnosis can decrease the mortality rate by making the right decision in the therapy procedure. These features lead to a reduction in medication time and socioeconomic burden. The current review article provides a comprehensive assessment for breast cancer diagnosis using nanomaterials and related technologies. Growing use of the nano/biotechnology domain in terms of electrochemical nanobiosensor designing was discussed in detail. In this regard, recent advances in nanomaterial applied for amplified biosensing methodologies were assessed for breast cancer diagnosis by focusing on the advantages and disadvantages of these approaches. We also monitored designing methods, advantages, and the necessity of suitable (nano) materials from a statistical standpoint. The main objective of this review is to classify the applicable biosensors based on breast cancer biomarkers. With numerous nano-sized platforms published for breast cancer diagnosis, this review tried to collect the most suitable methodologies for detecting biomarkers and certain breast cancer cell types.

Sulfur quantum dots as a novel platform to design a sensitive chemiluminescence probe and its application for Pb2+ detection.

The monitoring of Pb as a hazardous heavy metal element for the environment and human health is of high importance. In this study, a simple and sensitive chemiluminescence (CL) probe based on sulfur quantum dots (SQDs) was designed for the determination of Pb2+ . To the best of our knowledge, this is the first report on the analytical application of the CL method based on SQDs. For this purpose, SQDs were synthesized using a simple hydrothermal method and characterized using transmission electron microscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy and X-ray diffraction. Then, the direct CL of SQDs elicited by common oxidants was investigated. The highest CL intensity was observed for the SQDs-KMnO4 reaction, and its CL mechanism was studied. We indicated that the CL intensity of introduced system can be diminished as a result of the interaction between Pb2+ and SQDs, and exploited this fact for designing a CL-based probe for the determination of Pb2+ . The CL intensity of the SQDs-KMnO4 reaction was linearly quenched using Pb2+ in the range 50-2000 nM with a limit of detection of 16 nM (S/N = 3). The probe was used for the determination of Pb2+ in different water samples and the recovery results (95.2-102.8%) indicated the good analytical performance of the developed method.

Nickel oxide hollow microsphere for the chemiluminescence determination of tuberculostatic drug isoniazid.

In this article, nickel(II) oxide (NiO) hollow microspheres (HMSs) were fabricated and used to catalyze chemiluminescence (CL) reaction. The studied CL reaction is the luminol-oxygen reaction that was used as a sensitive analytical tool for measuring tuberculostatic drug isoniazid (IND) in pharmaceutical formulations and water samples. The CL method was established based on the suppression impact of IND on the CL reaction. The NiO HMSs were produced by a simple hydrothermal method and characterized by several spectroscopic techniques. The result of essential parameters on the analytical performance of the CL method, including concentrations of sodium hydroxide (NaOH), luminol, and NiO HMSs were investigated. At the optimum conditions, the calibration curve for IND was linear in the range of 8.00 × 10-7 to 1.00 × 10-4  mol L-1 (R2  = 0.99). A detection limit (3S) of 2.00 × 10-7  mol L-1 was obtained for this method. The acceptable relative standard deviation (RSD) was obtained for the proposed CL method (2.63%, n = 10) for a 5.00 × 10-6  mol L-1 IND solution. The mechanism of the CL reaction was also discussed.

Nanobody-based CAR-T cells for cancer immunotherapy.

Chimeric antigen receptor T-cell (CAR-T) therapy is the result of combining genetic engineering-based cancer immunotherapy with adoptive cell therapy (ACT). CAR-T therapy has been successful in treating various types of hematological cancers. CARs are receptors made of an extracellular domain, a membrane-spanning domain, and an intracellular domain. The extracellular domain of CARs harbors an antigen-targeting domain responsible for recognizing and binding cell surface-expressed target antigens. Conventionally, the single-chain fragment variable (scFv) of a monoclonal antibody (mAb) is used as the antigen-targeting domain of CARs. However, of late, researchers have exploited nanobodies for this aim based on numerous rationales including the small size of nanobodies, their stability, specificity, and high affinity, and their easy and feasible development process. Many findings have confirmed that nanobody-based CAR-Ts can be as functional as scFv-based CAR-Ts in preclinical and clinical settings. In this review, we discuss the advantages and disadvantages of scFvs and nanobodies in regards to their application as the targeting domain of CARs. Ultimately, we discuss various CAR target antigens which have been targeted using nanobody-based CAR-T cells for the treatment of different types of malignancies.

Application of green synthesized WO3-poly glutamic acid nanobiocomposite for early stage biosensing of breast cancer using electrochemical approach.

Biopolymer films have drawn growing demand for their application in the point of care domain owing to their biocompatibility, eco-friendly, and eligibility for in vivo analyses. However, their poor conductivity restricts their sensitivity in diagnostics. For high-quality electrochemical biosensor monitoring, two vital factors to be greatly paid attention are the effective merge of amplification modifiers with transducing surface and the superior linking across the recognition interface. Here, we introduce an enzyme-free electrochemical biosensor based on electrosynthesized biocompatible WO3/poly glutamic acid nano-biocomposites to address the hardships specific to the analysis of circulating proteins clinical samples. In addition to its green synthesis route, the poor tendency of both components of the prepared nano-biocomposite to amine groups makes it excellent working in untreated biological samples with high contents of proteins. Several electrochemical and morphological investigations (SEM, EDX, and dot mapping) were fulfilled to gain a reliable and trustful standpoint of the framework. By using this nanobiosensor, the concentration of HER-2 was detectable as low as 1 fg mL-1 with a wide linear response between 1 ng mL-1 and 1 fg mL-1. Meanwhile, the protocol depicted ideal specificity, stability, and reproducibility for the detection of HER-2 protein in untreated serum samples of breast cancer patients.

An efficient swarm intelligence approach to feature selection based on invasive weed optimization: Application to multivariate calibration and classification using spectroscopic data.

Variable selection plays a key role in classification and multivariate calibration. Variable selection methods are aimed at choosing a set of variables, from a large pool of available predictors, relevant to the analyte concentrations estimation, or to achieve better classification results. Many variable selection techniques have now been introduced among which, those which are based on the methodologies of swarm intelligence optimization have been more respected during a few last decades since they are mainly inspired by nature. In this work, a simple and new variable selection algorithm is proposed according to the invasive weed optimization (IWO) concept. IWO is considered a bio-inspired metaheuristic mimicking the weeds ecological behavior in colonizing as well as finding an appropriate place for growth and reproduction; it has been shown to be very adaptive and powerful to environmental changes. In this paper, the first application of IWO, as a very simple and powerful method, to variable selection is reported using different experimental datasets including FTIR and NIR data, so as to undertake classification and multivariate calibration tasks. Accordingly, invasive weed optimization - linear discrimination analysis (IWO-LDA) and invasive weed optimization- partial least squares (IWO-PLS) are introduced for multivariate classification and calibration, respectively.

Air-assisted liquid-liquid microextraction using floating organic droplet solidification for simultaneous extraction and spectrophotometric determination of some drugs in biological samples through chemometrics methods.

An air assisted liquid-liquid microextraction by applying the solidification of a floating organic droplet method (AALLME-SFOD) coupled with a multivariate calibration method, namely partial least squares (PLS), was introduced for the fast and easy determination of Atenolol (ATE), Propanolol (PRO) and Carvedilol (CAR) in biological samples via a spectrophotometric approach. The analytes would be extracted from neutral aqueous solution into 1-dodecanol as an organic solvent, using AALLME. In this approach a low-density solvent with a melting point close to room temperature was applied as the extraction solvent. The emulsion was immediately formed by repeatedly pulling in and pushing out the aqueous sample solution and extraction solvent mixture via a 10-mL glass syringe for ten times. After centrifugation, the extractant droplet could be simply collected from the aqueous samples by solidifying the emulsion at a lower than the melting point temperature. In the next step, analytes were back extracted simultaneously into the acidic aqueous solution. Derringer and Suich multi-response optimization were utilized for simultaneous optimizing the parameters of three analytes. This method incorporates the benefits of AALLME and dispersive liquid-liquid microextraction considering the solidification of floating organic droplets (DLLME-SFOD). Calibration graphs under optimized conditions were linear in the range of 0.30-6.00, 0.32-2.00 and 0.30-1.40µg mL-1 for ATE, CAR and PRO, respectively. Other analytical parameters were obtained as follows: enrichment factors (EFs) were found to be 11.24, 16.55 and 14.90, and limits of detection (LODs) were determined to be 0.09, 0.10 and 0.08µg mL-1 for ATE, CAR and PRO, respectively. The proposed method will require neither a highly toxic chlorinated solvent for extraction nor an organic dispersive solvent in the application process; hence, it is more environmentally friendly.

Interactions of cephalexin with bovine serum albumin: displacement reaction and molecular docking.

Introduction: The drug-plasma protein interaction is a fundamental issue in guessing and checking the serious drug side effects related with other drugs. The purpose of this research was to study the interaction of cephalexin with bovine serum albumin (BSA) and displacement reaction using site probes. Methods: The interaction mechanism concerning cephalexin (CPL) with BSA was investigated using various spectroscopic methods and molecular modeling method. The binding sites number, n, apparent binding constant, K, and thermodynamic parameters, ΔG0, ΔH0, and ΔS0 were considered at different temperatures. To evaluate the experimental results, molecular docking modeling was calculated. Results: The distance, r=1.156 nm between BSA and CPL were found in accordance with the Forster theory of non-radiation energy transfer (FRET) indicating energy transfer occurs between BSA and CPL. According to the binding parameters and ΔG0= negative values and ΔS0= 28.275 j mol-1K-1, a static quenching process is effective in the CPL-BSA interaction spontaneously. ΔG0 for the CPL-BSA complex obtained from the docking simulation is -28.99 kj mol-1, which is close to experimental ΔG of binding, -21.349 kj mol-1 that indicates a good agreement between the results of docking methods and experimental data. Conclusion: The outcomes of spectroscopic methods revealed that the conformation of BSA changed during drug-BSA interaction. The results of FRET propose that CPL quenches the fluorescence of BSA by static quenching and FRET. The displacement study showed that phenylbutazon and ketoprofen displaced CPL, indicating that its binding site on albumin is site I and Gentamicin cannot be displaced from the binding site of CPL. All results of molecular docking method agreed with the results of experimental data.

Carbon dots preparation as a fluorescent sensing platform for highly efficient detection of Fe(III) ions in biological systems.

Water-soluble carbon dots (CDs) were prepared, using a facile hydrothermal oxidation route of cyclic oligosaccharide α-CD, as carbon sources, and alkali as additives. The successful synthesis of CDs was confirmed by scanning electron microscopy (SEM), dynamic light scattering (DLS), FTIR, UV-visible absorption, and emission fluorescence. The characterizations showed that the prepared CDs are spherical and well-dispersed in water with average diameters of approximately 2 nm. These water-soluble CDs have excellent photo stability towards photo bleaching during 30 days. The obtained CDs showed a strong emission at the wavelength of 450 nm, with an optimum excitation of 360 nm. The fluorescence quenching of CDs in the presence of Fe(III) ions was used as fluorescent probes for quantifying Fe(III) ions in aqueous solution. Under optimum condition, the fluorescence intensity versus Fe(III) concentration gave a linear response, according to Stern-Volmer equation. The linearity range of the calibration curve and the limit of detection were 1.60×10(-5) to 16.6×10(-5) mol L(-1), and 6.05×10(-6) mol L(-1), respectively, which was in the range for serum analysis of Fe(III). It was concluded that the prepared CDs had a great potential as fluorescent probes for applications in analysis of Fe(III) ions in the blood serum samples, which is hardly interfered by other ions.

Direct chemiluminescence determination of penicillin G potassium and a chemometrical optimization approach.

A highly selective and simple chemiluminescence (CL) method for determination of penicillin G potassium (PGK) was developed. In the proposed method, CL was elicited from PGK upon its oxidation with H(2)O(2). The light emission was enhanced in the presence of N-cetyl-N,N,N-trimethylammonium bromide (CTMAB). An experimental design, central composite design (CCD), was used to realize the optimized variables, including pH, surfactant (CTMAB) and H(2)O(2) concentrations. Under optimum condition, the calibration graph was linear in the range 3.3 × 10(-3) -3.3 × 10(-1) mmol/L, with a detection limit of 8.8 × 10(-4) mmol/L for PGK. The precision was calculated by analysing samples containing 1.6 × 10(-1) mmol/L PGK (n = 5) and the relative standard deviation (RSD) was 1.40%. The utility of this method was demonstrated by determining PGK in pharmaceutical formulations for injection. The proposed method was validated by a reference method.

Study of aldehyde oxidase-catalyzed metabolic pathway of phenanthridine using MCR-ALS method.

Evaluation of metabolic pathways is one of the challenging areas in biological and pharmaceutical sciences. Phenanthridine oxidation to phenanthridinone is used commonly to study aldehyde oxidase activity. This reaction could pass through phenanthridine N-oxide intermediate. In the present study, the application of multivariate curve resolution, optimized by alternating least squares (MCR-ALS) to investigate this metabolic pathway has been described. The results obtained from MCR-ALS analysis along with those obtained from the use of potassium ferrocyanide method indicated that phenanthridine is directly oxidized to phenanthridinone by rat liver aldehyde oxidase without passing through phenanthridine N-oxide intermediate. It was also found that the later compound is not metabolized by this enzyme.

Simultaneous Determination of 6-Mercaptopurine and its Oxidative Metabolites in Synthetic Solutions and Human Plasma using Spectrophotometric Multivariate Calibration Methods.

INTRODUCTION: 6-Mercaptopurine (6MP) is an important chemotherapeutic drug in the conventional treatment of childhood acute lymphoblastic leukemia (ALL). It is catabolized to 6-thiouric acid (6TUA) through 8-hydroxo-6-mercaptopurine (8OH6MP) or 6-thioxanthine (6TX) intermediates. METHODS: High-performance liquid chromatography (HPLC) is usually used to determine the contents of therapeutic drugs, metabolites and other important biomedical analytes in biological samples. In the present study, the multivariate calibration methods, partial least squares (PLS-1) and principle component regression (PCR) have been developed and validated for the simultaneous determination of 6MP and its oxidative metabolites (6TUA, 8OH6MP and 6TX) without analyte separation in spiked human plasma. Mixtures of 6MP, 8-8OH6MP, 6TX and 6TUA have been resolved by PLS-1 and PCR to their UV spectra. RESULTS: Recoveries (%) obtained for 6MP, 8-8OH6MP, 6TX and 6TUA were 94.5-97.5, 96.6-103.3, 95.1-96.9 and 93.4-95.8, respectively, using PLS-1 and 96.7-101.3, 96.2-98.8, 95.8-103.3 and 94.3-106.1, respectively, using PCR. The NAS (Net analyte signal) concept was used to calculate multivariate analytical figures of merit such as limit of detection (LOD), selectivity and sensitivity. The limit of detections for 6MP, 8-8OH6MP, 6TX and 6TUA were calculated to be 0.734, 0.439, 0.797 and 0.482 µmol L-1, respectively, using PLS and 0.724, 0.418, 0783 and 0.535 µmol L-1, respectively, using PCR. HPLC was also applied as a validation method for simultaneous determination of these thiopurines in the synthetic solutions and human plasma. CONCLUSION: Combination of spectroscopic techniques and chemometric methods (PLS and PCR) has provided a simple but powerful method for simultaneous analysis of multicomponent mixtures.

Quantitative analysis by resolving variation matrices of pH-Spectrophotometric titration data using Self-Modeling Curve Resolution.

A new method is proposed for resolving pH-spectrophotometric titration data to determine mixtures of monoprotic acids. The method uses variation matrices to circumvent the rank deficiency problem of such data by shifting to another target, namely the reaction space. Self-modeling curve resolution is used to resolve variation matrices of pH-spectrophotometric titration data for acid mixtures. The variation matrix is obtained by subtracting the zero-point spectrum (e.g., acidic spectrum) from each spectrum at each pH value. Mean-centering window evolving factor analysis is used to identify the local reaction map. Reaction spectra can be estimated using selective regions of the local reaction map, from which reaction extent vectors can be obtained by alternating least-squares optimization. It was shown that quantitative analysis can be performed by augmentation of the variation matrix of the unknown and standard samples and comparison of obtained reaction extent curves. The applicability of the proposed method was evaluated using model data for binary and ternary mixtures of monoprotic acids. pH-spectrophotometric titration data for real binary mixtures of tartrazine/sunset yellow were also investigated using the proposed method and their concentration were determined in a real sample.

A new multi-wavelength model-based method for determination of enzyme kinetic parameters.

Lineweaver-Burk plot analysis is the most widely used method to determine enzyme kinetic parameters. In the spectrophotometric determination of enzyme activity using the Lineweaver-Burk plot, it is necessary to find a wavelength at which only the substrate or the product has absorbance without any spectroscopic interference of the other reaction components. Moreover, in this method, different initial concentrations of the substrate should be used to obtain the initial velocities required for Lineweaver-Burk plot analysis. In the present work, a multi-wavelength model-based method has been developed and validated to determine Michaelis-Menten constants for some enzyme reactions. In this method, a selective wavelength region and several experiments with different initial concentrations of the substrate are not required. The absorbance data of the kinetic assays are fitted by non-linear regression coupled to the numeric integration of the related differential equation. To indicate the applicability of the proposed method, the Michaelis-Menten constants for the oxidation of phenanthridine, 6-deoxypenciclovir and xanthine by molybdenum hydroxylases were determined using only a single initial concentration of the substrate, regardless of any spectral overlap.

Fluorescence quenching study of quercetin interaction with bovine milk xanthine oxidase.

Quercetin is a natural flavonoid with many important therapeutic properties. The interaction of this polyphenolic compound bovine milk xanthine oxidase as one of its major target proteins was studied using fluorescence quenching method for the first time. It was found that the fluorescence quenching of xanthine oxidase occurs through a static mechanism. The results revealed the presence of a single binding site on xanthine oxidase with the binding constant value equals to 1.153 x 10(4) l mol(-1) at 310 K and pH 7.4. The thermodynamic parameters were also calculated at different temperatures. The enthalpy and entropy changes were found as -10.661 kJ mol(-1) and +43.321 J mol(-1) K(-1) indicating that both hydrogen binding and hydrophobic are involved in the interaction of this polyphenolic natural compound with xanthine oxidase. The results may provide a ground for further studies with different flavonoids to find a safe alternative for allopurinol, the only xanthine oxidase inhibitor with clinical application.

Simultaneous spectrophotometric determination of benzoic acid, sorbic acid, and ascorbic acid using a net analyte signal-based method.

The net analyte preprocessing/classical least-squares (NAP/CLS) method is a simple chemometric method that has been used for the simultaneous spectrophotometric determination of benzoic acid, sorbic acid, and ascorbic acid. The obtained results indicated that the performances of the NAP/CLS and partial least-squares methods were almost identical. The net analyte signal (NAS) concept was also used to calculate multivariate analytical figures of merit, such as LOD, selectivity, and sensitivity. Wavelength selection was applied based on the concept of NAS regression, and improved the method performance in samples containing nonmodeled interferences. The method afforded recoveries in the range of 98-105%. The proposed method was successfully applied to determination of the analytes in an Iranian soft drink.