Combination of developed in-house method and application of Eichrom Sr resin to determine the radioactivity of <Superscript>90</Superscript>Sr in environmental sample

A method is described for the determination of ⁹⁰Sr in environmental samples using combination of developed in-house method, Eichrom Sr resin and Beta Counter. Strontium was efficiently, rapidly and simply separated from Ca and other interfering matrix components by Eichrom Sr resin. All the results in general showed good accuracy, high precision, reliable and in good agreement between these two measured and certified value of SRM (i.e. IAEA-375, IAEA-326, IAEA-152 and IAEA-414). As a whole, the procedure described in this work notably improves conventional methods in particular concerning the time needed, sample volume, safer and others. Thus, the introduced method was successfully performed and will be applied to actual sample for the determination of ⁹⁰Sr in different environmental materials such as soil, sediments, milk, biological sample, water etc.     

Current advances in molecularly imprinted polymers and their release mechanisms in drug delivery systems

Molecularly imprinted polymer (MIP) has gained wide interest among researchers due to its unique molecular recognition of the template that is suitable as a drug carrier. Therefore, the preparation and formulation of the MIP are significant to suit the needs of the intended use. Due to its significance in drug delivery, this review aims to highlight various methods in the preparation of MIP, the composition for both controlled and stimuli-responsive drug delivery systems, and the release mechanism of the drugs. In drug delivery systems, MIP should have a sustained release performance as well as flexibility in surface modification for targeted delivery via a range of stimuli-responses, including  external stimuli (magnetic, light) and internal stimuli (pH, temperature, redox, biological). The properties of sustained release and targeted delivery of the MIP can improve the drug's therapeutic efficacy as well as the breakthrough for the tumor targeting application.     

Five‐coordinate dinuclar cobalt (II), copper (II), zinc (II) and cadmium (II) complexes with 4‐bromo‐N‐(2‐pyridinylmethylene)benzenamine: Synthesis,characterisation and methyl methacrylate polymerization

A series of late transition metal complexes, [(bpma)Co(μ – Cl)Cl] ₂ , [(bpma)Cu(μ – Cl)Cl] ₂ , [(bpma)Zn(μ – Cl)Cl] ₂ and [(bpma)Cd(μ – Br)Br] ₂ (where bpma is 4‐bromo‐N‐((pyridin‐2‐yl)methylene)benzenamine) have been synthesized and structurally characterized. The X‐ray structures of dimeric complexes [(bpma)M(μ – X)X] ₂ (M = Co, Cu and Zn, X = Cl; M = Cd, X = Br) showed a distorted 5‐coordinate trigonal bipyramidal geometry involving two nitrogen atoms of N,N‐bidentate ligand, two bridged and one terminal halogen atoms. The complex [(bpma)Cu(μ – Cl)Cl] ₂ revealed the highest catalytic activity for the polymerisation of methyl methacrylate in the presence of modified methylaluminoxane with an activity of 9.14 × 10⁴ g PMMA/mol·Cu·h at 60 °C and afforded syndiotactic poly (methylmethacrylate) (rr = 0.69).     

An insight to the molecular interactions of the FDA approved HIV PR drugs against L38L↑N↑L PR mutant

The aspartate protease of the human immune deficiency type-1 virus (HIV-1) has become a crucial antiviral target in which many useful antiretroviral inhibitors have been developed. However, it seems the emergence of new HIV-1 PR mutations enhances drug resistance, hence, the available FDA approved drugs show less activity towards the protease. A mutation and insertion designated L38L↑N↑L PR was recently reported from subtype of C-SA HIV-1. An integrated two-layered ONIOM (QM:MM) method was employed in this study to examine the binding affinities of the nine HIV PR inhibitors against this mutant. The computed binding free energies as well as experimental data revealed a reduced inhibitory activity towards the L38L↑N↑L PR in comparison with subtype C-SA HIV-1 PR. This observation suggests that the insertion and mutations significantly affect the binding affinities or characteristics of the HIV PIs and/or parent PR. The same trend for the computational binding free energies was observed for eight of the nine inhibitors with respect to the experimental binding free energies. The outcome of this study shows that ONIOM method can be used as a reliable computational approach to rationalize lead compounds against specific targets. The nature of the intermolecular interactions in terms of the host–guest hydrogen bond interactions is discussed using the atoms in molecules (AIM) analysis. Natural bond orbital analysis was also used to determine the extent of charge transfer between the QM region of the L38L↑N↑L PR enzyme and FDA approved drugs. AIM analysis showed that the interaction between the QM region of the L38L↑N↑L PR and FDA approved drugs are electrostatic dominant, the bond stability computed from the NBO analysis supports the results from the AIM application. Future studies will focus on the improvement of the computational model by considering explicit water molecules in the active pocket. We believe that this approach has the potential to provide information that will aid in the design of much improved HIV-1 PR antiviral drugs.     

Synthesis,characterisation, and X-ray structures of zinc(II) complexes bearing camphor-based ethyleneamineimines as pre-catalysts for heterotactic-enriched polylactide from rac-lactide

Transition Metal Chemistry - A series of Zn(II) complexes bearing camphor-based ethyleneamine derivatives, [LnZnCl2]...     

Novel Flurbiprofen‐iminothiazoline Hybrid Compounds: Synthesis and Characterization

A series of novel flurbiprofen‐iminothiazoline hybrid compounds of biological interest were synthesized by base‐catalyzed heterocyclization of the flurbiprofen thioureas with 4‐chloro‐α‐bromoacetophenone in dry dichloromethane.     

Synthesis of Cholesterol-Conjugated Magnetic Nanoparticles for Purification of Human Paraoxonase 1

Human serum paraoxonase 1 (PON1) is known as an antioxidant and is also involved in the detoxification of many compounds. In this study, a novel purification strategy was employed to purify the PON1 by using cholesterol-conjugated magnetic nanoparticles. Magnetic nanoparticles were synthesized and conjugated with cholesterol through diazotized p-aminohippuric acid. In Fourier transform infrared spectrum of cholesterol-p-aminohippuric acid-Fe₃O₄ nanoparticles, the appearance of peaks at 3,358.3, 1,645 cm⁻¹, and at 2,334.9 cm⁻¹ confirmed the conjugation. The molecular weight of purified PON1 was nearly 45 kDa on sodium dodecyl sulfate (SDS)–polyacrylamide gel electrophoresis (PAGE), and isoelectric point was 5.3. The specific activity was 438 U mg⁻¹ protein, and the purification fold was 515 with 73% yield. The K _m values were 1.3 and 0.74 mM with paraoxon and phenyl acetate, respectively. Western blot of 2D-PAGE confirmed the homogeneity and stability of the enzyme. Mg⁺², Mn⁺², glycerol, (NH₄)₂SO₄, PEG 6000, Triton X-100, and phenylmethylsulfonyl fluoride did not show any effect on activity. Pb⁺², Co⁺², Zn²⁺, ethanol, β-mercaptoethanol, and acetone reduced the activity while Ni²⁺, Cd²⁺, Cu²⁺, iodoacetic acid, SDS, dimethylformamide, DMSO inhibited the activity. In vitro enzyme activity was slightly reduced by acetyl salicylic and acetaminophen and reduced 50% with amino glycosides and ampicillin antibiotics at concentrations of 0.6 and 30 mg ml⁻¹, respectively. This is the first report for the synthesis of cholesterol-conjugated magnetic nanoparticles for simple purification of PON1 enzyme.     

A novel solid-phase equivalent to the triflate group and its application to traceless linking and cross-coupling-release strategies

A solid-phase version of the triflate group has been developed and its use demonstrated in traceless linking of aromatics and cross-coupling release strategies.     

Qualitative characterization of the diffusion of cationic-modified PVA into the cellulose fiber pores

In this work, the diffusion of cationic poly (vinyl alcohol) (CPVA) with well-defined structures into the pores of bleached kraft fibers was investigated at equilibrium level of adsorption by means of adsorption, solute exclusion technique (SET), and nuclear magnetic resonance (NMR) relaxation method. The results showed that the interaction between CPVA and dextran polymers was weak, which allowed us to use the SET method to investigate the variation in the pore size of fibers upon diffusing CPVAs. Both adsorption and SET methods confirmed the diffusion of CPVA polymers into the fiber pores. However, the NMR technique was unable to reflect the pore size changes. The main reason for such results was probably the error that occurred in removing water between fibers via applying the water retention value (WRV) test prior to the NMR analysis. In fact, not all of the water on the fiber surface, especially on the surface of CPVA-modified fibers, could be removed by the WRV, introducing some error in the NMR analysis.