Reprint of: Extraction of fluoxetine from aquatic and urine samples using sodium dodecyl sulfate-coated iron oxide magnetic nanoparticles followed by spectrofluorimetric determination

A new method based on the combination of magnetic solid phase extraction (MSPE) and spectrofluorimetric determination was developed for isolation and preconcentration of fluoxetine form aquatic and biological samples using sodium dodecyl sulfate (SDS) coated Fe₃O₄ nanoparticles (NPs) as a sorbent. The unique properties of Fe₃O₄ NPs including high surface area and strong magnetism were utilized effectively in the MSPE process. Effect of different parameters influencing the extraction efficiency of fluoxetine including the amount of Fe₃O₄ and SDS, pH value, sample volume, extraction time, desorption solvent and time were optimized. Under optimized condition, the method was successfully applied to the extraction of fluoxetine from water and urine samples and absolute recovery amount of 85%, detection limit of 20 μg L⁻¹ and a relative standard deviation (RSD) of 1.4% were obtained. The method linear response was over a range of 50–1000 μg L⁻¹ with R² = 0.9968. The relative recovery in different aquatic and urine matrices were investigated and values of 80% to 104% were obtained. The whole procedure showed to be conveniently fast, efficient and economical for extraction of fluoxetine from environmental and biological samples.     

A high throughput glucocerebrosidase assay using the natural substrate glucosylceramide

Glucocerebrosidase is a lysosomal enzyme that catalyzes the hydrolysis of glucosylceramide to form ceramide and glucose. A deficiency of lysosomal glucocerebrosidase due to genetic mutations results in Gaucher disease, in which glucosylceramide accumulates in the lysosomes of certain cell types. Although enzyme replacement therapy is currently available for the treatment of type 1 Gaucher disease, the neuronopathic forms of Gaucher disease are still not treatable. Small molecule drugs that can penetrate the blood-brain barrier, such as pharmacological chaperones and enzyme activators, are new therapeutic approaches for Gaucher disease. Enzyme assays for glucocerebrosidase are used to screen compound libraries to identify new lead compounds for drug development for the treatment of Gaucher disease. But the current assays use artificial substrates that are not physiologically relevant. We developed a glucocerebrosidase assay using the natural substrate glucosylceramide coupled to an Amplex-red enzyme reporting system. This assay is in a homogenous assay format and has been miniaturized in a 1,536-well plate format for high throughput screening. The assay sensitivity and robustness is similar to those seen with other glucocerebrosidase fluorescence assays. Therefore, this new glucocerebrosidase assay is an alternative approach for high throughput screening.     

Synthesis, cytotoxicity and spectroscopy studies of a new copper (II) complex: calf thymus DNA and T47D as targets

A water-soluble Cu (II) complex [(dien)Cu(??-1,6-DAH)Cu(dien) (NO₃)₂](NO₃)₂ has been synthesized and its effect on the carrier model DNA structure and cancer cell line proliferation was investigated. In this regard, calf thymus DNA (CT-DNA) and human breast cancer cell line, T47D, were the targets. The effect of the complex on DNA structure was investigated by means of UV/vis, fluorescence and circular dichroism (CD) spectroscopic techniques as well as dynamic light scattering (DLS), zeta potential analysis and docking assay for more analysis. The UV?Cvis absorption spectra of complex with DNA showed a slight red shift and hypochromic effect, which indicated the intercalation and electrostatic effect of complex with CT-DNA. Using ethidium bromide (EB) as a probe in fluorescence studies revealed that complex can quench the EB?CDNA fluorescence emission at different temperatures. Besides, the far UV?CCD studies displayed that the complex induces changes in the secondary structure of CT-DNA and can increase the melting temperature of DNA up to 14?°C. The DLS and zeta potential measurements confirmed the electrostatic interaction of complex with the negatively charged DNA and subsequent DNA condensation. Besides, computational studies reflect that major and minor groove binding are two modes of interaction between complex and DNA. On the other hand, growth inhibition of the complex toward T47D cell line was measured using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, which showed no cytotoxic properties.     

β-Mannosidase and β-hexosaminidase inhibitors: synthesis of 1,2-bis-epi-valienamine and 1-epi-2-acetamido-2-deoxy-valienamine from d-mannose

A partially protected C-5C-5a unsaturated carbasugar with α-lyxo configuration is synthesised in five steps and 26% overall yield from a known mannose-derived hemiacetal, using ring-closing metathesis as a key step. This carbasugar is converted into valienamine derivatives with β-lyxo (i.e., corresponding to β-manno at C-1–C-4), α-lyxo (i.e., corresponding to α-manno at C-1–C-4) and β-2-acetamido-2-deoxy-xylo (i.e., corresponding to β-GlcNAc at C-1–C-4) configurations. This is the first report of the synthesis of the β-lyxo compound, 1,2-bis-epi-valienamine, which was found to inhibit Cellulomonas fimi β-mannosidase (CfMan2A) with K_i 140 μM. We report the crystal structures of three protected C-5C-5a unsaturated carbasugars with lyxo configuration.     

A numerical scheme for a class of nonlinear Fredholm integral equations of the second kind

In this paper an iterative approach for obtaining approximate solutions for a class of nonlinear Fredholm integral equations of the second kind is proposed. The approach contains two steps: at the first one, we define a discretized form of the integral equation and prove that by considering some conditions on the kernel of the integral equation, solution of the discretized form converges to the exact solution of the problem. Following that, in the next step, solution of the discretized form is approximated by an iterative approach. We finally on some examples show the efficiency of the proposed approach.     

Antibacterial Nanomaterials: Mechanisms,Impacts on Antimicrobial Resistance and Design Principles

Antimicrobial resistance (AMR) is one of the biggest threats to the environment and health. AMR rapidly invalidates conventional antibiotics, and antimicrobial nanomaterials have been increasingly explored as alternatives. Interestingly, several antimicrobial nanomaterials show AMR-independent antimicrobial effects without detectable new resistance and have therefore been suggested to prevent AMR evolution. In contrast, some are found to trigger the evolution of AMR. Given these seemingly conflicting findings, a timely discussion of the two faces of antimicrobial nanomaterials is urgently needed. This review systematically compares the killing mechanisms and structure-activity relationships of antibiotics and antimicrobial nanomaterials. We then focus on nano-microbe interactions to elucidate the impacts of molecular initiating events on AMR evolution. Finally, we provide an outlook on future antimicrobial nanomaterials and propose design principles for the prevention of AMR evolution.