Fabrication and characterization of RNA aptamer microarrays for the study of protein–aptamer interactions with SPR imaging

RNA microarrays were created on chemically modified gold surfaces using a novel surface ligation methodology and employed in a series of surface plasmon resonance imaging (SPRI) measurements of DNA–RNA hybridization and RNA aptamer–protein binding. Various unmodified single-stranded RNA (ssRNA) oligonucleotides were ligated onto identical 5′-phosphate-terminated ssDNA microarray elements with a T4 RNA ligase surface reaction. A combination of ex situ polarization modulation FTIR measurements of the RNA monolayer and in situ SPRI measurements of DNA hybridization adsorption onto the surface were used to determine an ssRNA surface density of 4.0 × 10(12) molecules/cm(2) and a surface ligation efficiency of 85 ± 10%. The surface ligation methodology was then used to create a five-component RNA microarray of potential aptamers for the protein factor IXa (fIXa). The relative surface coverages of the different aptamers were determined through a novel enzymatic method that employed SPRI measurements of a surface RNase H hydrolysis reaction. SPRI measurements were then used to correctly identify the best aptamer to fIXa, which was previously determined from SELEX measurements. A Langmuir adsorption coefficient of 1.6 × 10(7) M(−1) was determined for fIXa adsorption to this aptamer. Single-base variations from this sequence were shown to completely destroy the aptamer–fIXa binding interaction

Dendritic glycopolymers based on dendritic polyamine scaffolds: view on their synthetic approaches, characteristics and potential for biomedical applications

In this review we highlight the potential for biomedical applications of dendritic glycopolymers based on polyamine scaffolds. The complex interplay of the molecular characteristics of the dendritic architectures and their specific interactions with various (bio)molecules are elucidated with various examples. A special role of the individual sugar units attached to the dendritic scaffolds and their density is identified, which govern ionic and H-bond interactions, and biological targeting, but to a large extent are also responsible for the significantly reduced toxicity of the dendritic glycopolymers compared to their polyamine scaffolds. Thus, the application of dendritic glycopolymers in drug delivery systems for gene transfection but also as therapeutics in neurodegenerative diseases has great promisePublikacja w ramach programu Royal Society of Chemistry "Gold for Gold" 2014 finansowanego przez Uniwersytet Łódzk

Non-invasive assessment of coronary artery bypass graft patency using 16-slice computed tomography angiography

<p>Abstract</p> <p>Background</p> <p>Invasive coronary angiography is the gold standard means of imaging bypass vessels and carries a small but potentially serious risk of local vascular complications, including myocardial infarction, stroke and death. We evaluated computed tomography as a non-invasive means of assessing graft patency.</p> <p>Methods</p> <p>Fifty patients with previous coronary artery bypass surgery who were listed for diagnostic coronary angiography underwent contrast enhanced computed tomography angiography using a 16-slice computed tomography scanner. Images were retrospectively gated to the electrocardiogram and two dimensional axial, multiplanar and three dimensional reconstructions acquired. Sensitivity, specificity, positive and negative predictive value, accuracy and level of agreement for detection of graft patency by multidetector computed tomography.</p> <p>Results</p> <p>A total of 116 grafts were suitable for analysis. The specificity of CT for the detection of graft patency was 100%, with a sensitivity of 92.8%, positive predictive value 100%, negative predictive value 85.8% and an accuracy of 94.8%. The kappa value of agreement between the two means of measuring graft patency was 0.9. Mean radiation dose was 9.0 ± 7.2 mSv for coronary angiography and 18.5 ± 4 mSv for computed tomography. Pooled analysis of eight studies, incorporating 932 grafts, confirmed a 97% accuracy for the detection of graft patency by multidetector computed tomography.</p> <p>Conclusion</p> <p>Computed tomography is an accurate, rapid and non-invasive method of assessing coronary artery bypass graft patency. However, this was achieved at the expense of an increase in radiation dose.</p

Developing international social capital: The role of communities of practice and clustering

© 2018 Elsevier Ltd One criteria regarding where to invest in foreign markets is linked to the international social capital (ISC) that exists on the place, which enables the access to local knowledge and other location-specific advantages. There are alternative ways to create and make use of that ISC that are still unexplored by International Business literature. In this paper, we study the geographic communities of practice (CoP) that are formed by FDI firms from the same country-of-origin (the so-called country-of-origin clusters). For that purpose, the paper adopts a qualitative methodological approach through an inductive case study of expatriates from 13 Spanish subsidiaries co-located in China. Our findings suggest that there are particular mechanisms based on the informal connections and repeated interactions facilitated by a common language and non-competitive relationships that create an ISC in the CoP. Moreover, our analysis shows there is a heterogeneity in the way these mechanisms are developed and used by the member firms, and this is due to organizational and individual factors, as well as leadership dynamics. Our work contributes to Internationalization and Network theories by identifying unexplored mechanisms through which the ISC is developed at the host country level. Besides, it helps identifying competences (i.e. clustering competences) that help expatriate managers to be successful in their international assignments

Semi-crystalline diblock copolymer nano-objects prepared via RAFT alcoholic dispersion polymerization of stearyl methacrylate

The RAFT dispersion polymerization of stearyl methacrylate (SMA) is conducted in ethanol at 70 °C using a poly(2-(dimethylamino)ethyl methacrylate) [PDMA] chain transfer agent. The growing PSMA block becomes insoluble in ethanol, which leads to polymerization-induced self-assembly (PISA) and hence produces a range of copolymer morphologies depending on the precise PDMAy–PSMAx formulation. More specifically, pure phases corresponding to either spherical nanoparticles, worm-like nanoparticles or vesicles can be prepared as judged by transmission electron microscopy. However, the worm phase space is relatively narrow, so construction of a detailed phase diagram is required for reproducible syntheses of this morphology. Inter-digitation of the stearyl (C18) side-groups leads to a semi-crystalline PSMA core block and the effect of systematically varying the mean degree of polymerization of both the PDMA and PSMA blocks on the Tm and Tc is investigated using differential scanning calorimetry. Finally, it is demonstrated that these cationic nanoparticles can be employed as colloidal templates for the in situ deposition of silica from aqueous solution

Voltammetric determination of catechol based on a glassy carbon electrode modified with a composite consisting of graphene oxide and polymelamine

The authors describe an voltammetric catechol (CC) assay based on the use of a glassy carbon electrode (GCE) modified with a composite consisting of graphene oxide and polymelamine (GO/PM). The modified GCE was characterized by field emission scanning electron microscopy, elemental analysis, Raman spectroscopy and FTIR. Cyclic voltammetry reveals a well-defined response to CC, with an oxidation peak current that is distinctly enhanced compared to electrodes modified with GO or PM only. The combined synergetic activity of GO and PM in the composite also results in a lower oxidation potential. Differential pulse voltammetry (DPV) shows a response that is linear in the 0.03 to 138 μM CC concentration range. The detection limit is 8 nM, and the sensitivity is 0.537 μA⋅μM−1 ⋅cm−2 . The sensor is selective for CC even in the presence of potentially interfering compounds including hydroquinone, resorcinol and dopamine. The modified GCE is highly reproducible, stable, sensitive, and shows an excellent practicability for detection of CC in water samples