A set of polymers was imprinted with (-)-ephedrine using two different initiators. A chemometrics approach was used to optimise experiments aimed at analysis of the interplay of parameters such as polymerisation time, temperature and percentage of initiator. The results presented demonstrate the importance of keeping the right balance between these various parameters of polymerisation conditions. It is shown that enhancing one single parameter such as polymer rigidity does not necessarily improve polymer performance. In general it could be concluded that MIPs should be synthesised over a long period of time using low concentration of initiator and low temperature. The best selectivity was achieved for polymers prepared by photo-initiation with 2,2-dimethoxy-2-phenylacetophenone as initiator.
We describe the preparation of multibranched gold−silica−molecularly imprinted polymer (bAu@mSiO 2 @ MIP) core−shell nanoparticles, with their specific ability to recognize enrofloxacin (ENRO), and their application as labelfree nanosensors for the specific detection of the antimicrobial by surface-enhanced Raman scattering. The use of these nanocomposites results in a large enhancement of the Raman scattering of ENRO upon binding of an antibiotic to the selective recognition sites in the MIP. These are in the proximity of the gold core branches that act as intrinsic hot spots providing highly localized and strongly enhanced electromagnetic fields caused by plasmon resonance. The effect of the multibranched morphology of the gold cores (bAu) on the optical spectroscopic response of the bAu@mSiO 2 @MIP nanosensors is investigated with the aim of improving ENRO detection. The optimized nanostructures allowed us to achieve a detection limit of 1.5 nM for ENRO, which is 2 orders of magnitude lower than those for previously reported Au@MIP nanosensors, additionally providing negligible cross-reactivity toward other potential interfering species.
This
paper reports the preparation of versatile electrochemical
biosensing platforms for the simple, rapid, and PCR-independent detection
of the most frequent DNA methylation marks (5-methylcytosine, 5-mC,
and/or 5-hydroxymethylcytosine, 5-hmC) both at global and gene-specific
levels. The implemented strategies, relying on the smart coupling
of immuno-magnetic beads (MBs), specific DNA probes and amperometric
detection at screen-printed carbon electrodes (SPCEs), provided sensitive
and selective determination of the target methylated DNAs in less
than 90 min with a great reproducibility and demonstrated feasibility
for the simultaneous detection of the same or different cytosine epimarks
both at global level and in different loci of the same gene or in
different genes. The bioplatforms were applied to determine global
methylation events in paraffin-embedded colorectal tissues and specific
methylation at promoters of tumor suppressor genes in genomic DNA
extracted from cancer cells and paraffin-embedded colorectal tissues,
and in serum without previous DNA extraction from cancer patients.
The present work describes the development of a sensitive and highly selective innovative method for the simultaneous detection of six fluoroquinolone (FQ) antimicrobials (enrofloxacin, ciprofloxacin, norfloxacin, levofloxacin, danofloxacin, and sarafloxacin) in water samples. This detection is based on online solid phase extraction, coupled to liquid chromatography (LC), using for the first time tailor-made molecularly imprinted microspherical polymer particles prepared via precipitation polymerization. Various parameters affecting the extraction efficiency of the polymer have been optimized to reduce nonspecific interactions and to achieve selective uptake of the antibiotics from real samples. The method shows good recoveries ranging between 62% and 102% (V = 25 mL) for the different FQs tested and excellent interday and intraday precision with relative standard deviation (RSD) values between 2-5% and 2-6%, respectively. The detection limits were between 1-11 ng L(-1) (drinking water) and 1-12 ng L(-1) (fish farm water) when 25 mL samples were processed. The polymer showed selectivity for FQs containing a piperazine moiety whereas no retention was found for other antibiotics or nonrelated compounds. The method has been applied to the analysis of trace amounts of the FQs tested in drinking and fish farm water samples with excellent recoveries (>91%) and good precision (RSDs <5%).
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