1,721,036 research outputs found
FABRICATION OF POLYMER ARRAYS FOR SENSOR TECHNOLOGY
No full textThe parallel deposition of polymers made with several functional monomers in a microchip format or onto an appropriate solid support could find a wide range of applications in sensing, combinatorial and high-throughput screening.
We here report an innovative fabrication approach for the elaboration of polymer microarrays bearing polymer dots typically 300μm in diameter, fabricated in situ on a glass cover slip via CO2 laser pulse initiated polymerisation. Using such laser in a format that allows spatial positioning or steering of the beam together with appropriate parameters, it is possible to locally heat a surface to the appropriate temperature which initiates thermal polymerisation of suitable monomer mixtures, resulting in spatial patterning of the polymers. Following this approach we report the fabrication of a heterogeneous microarray of 14 polymers on a single microfluidic chip, starting from different commonly used functional monomers.
As a different technology to generate polymeric arrays, a parallel pin deposition onto glass slides using a model eight pins machinery system is also presented here. Pins uptakes of 0.8μL functional monomer solutions were followed by dot depositions performed onto dichlorodimethylsilane modified borosilicate glass slides. Photo-polymerisation under a UV lamp for 5min was further performed to obtain and array of millimetre sized polymer dots.
We believe that these new technologies may find wide applicability in the fields of combinatorial and high-throughput screening for the development of affinity materials and molecularly imprinted polymers (MIPs), (bio)chemical sensing and material biocompatibility studies, particularly when low sample volumes are available
‘Gate-effect’ in templated polyacrylamide membranes influences the electro-transport of proteins and finds applications in proteome analysis.
No full textTemplating is an effective way for the structural modifications of a material and hence for altering its functional properties. Here protein imprinting was exploited to alter polymeric polyacrylamide (PAA) membranes. The sieving properties and selection abilities of the material formed were evaluated by studying the electrically driven transport of various proteins across templated PAA membranes. The sieving properties correlated with the templating process and depended on the quantity of template used during the polymerisation. For 1 mg/mL protein-templated membranes a 'gate effect' was shown, which induced a preferential migration of the template and of similar-size proteins. Such template preferential electrotransport was exploited for the selective removal of certain proteins in biological fluids prior to proteome analysis (depletion of albumin from human serum); the efficiency of the removal was demonstrated by analysing the serum proteome by two-dimensional electrophoresis experiments
Surface imprinted beads for the recognition of human serum albumin
Full text linkThe synthesis of poly-aminophenylboronic acid (ABPA) imprinted beads for the
recognition of the protein human serum albumin (HSA) is reported. In order to
create homogeneous recognition sites, covalent immobilisation of the template
HSA was exploited. The resulting imprinted beads were selective for HSA. The
indirect imprinting factor (IF) calculated from supernatant was 1.6 and the
direct IF, evaluated from the protein recovered from the beads, was 1.9. The
binding capacity was 1.4 mg/g, which is comparable to commercially available
affinity materials. The specificity of the HSA recognition was evaluated with
competitive experiments, indicating a molar ratio 4.5/1 of competitor was
necessary to displace half of the bound HSA. The recognition and binding of the
imprinted beads was also tested with a complex sample, human serum and targeted
removal of HSA without a loss of the other protein components was demonstrated.
The easy preparation protocol of derivatised beads and a good protein
recognition properties make the approach an attractive solution to analytical
and bio-analytical problems in the field of biotechnology
Synthesis of controlled polymeric cross-linked coatings via iniferter polymerisation in the presence of tetraethyl thiuram disulphide chain terminator
Full text linkA “grafting from” approach has been used for controlled deposition of cross-
linked polymers by living radical polymerisation. Borosilicate glass was
modified with N,N-diethylaminodithiocarbamoylpropyl(trimethoxy)silane, in order
to confine the iniferter reactive groups solely at its surface, then placed in
solution with monomers and cross-linker. The polymerisation was initiated by UV
irradiation. Formation of the cross-linked polymers was studied in terms of time
course of the reaction, type of monomers incorporated and influence of oxygen.
Grafted surfaces were characterised by AFM, FT-IR, ellipsometry and contact
angle measurements. The ability to control the grafted layer improved
dramatically when the chain terminator agent, N,N-N′,N′-tetraethyl thiuram
disulphide (TED) was added. Upon irradiation TED increases the concentration of
passive capping radicals and decreases the possibility of recombination of
active macro-radicals, thus prolonging their lifetime. In the absence of TED the
thickness of produced coatings was below 10 nm. TED added at different
concentrations assisted in the formation of grafted layers of 10–130 nm
thickness. Iniferter chemistry in the presence of TED can be used for growing
nanometre-scale polymer layers on solid supports. It constitutes a robust
general platform for controlled grafting and offer a general solution to address
the needs of surface derivatisation in sensors
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Development of a new MIP-based sensor based on MIP particles entrapment in electrosynthetized polymer films
No full textVariations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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