Copper ions play a major role in biological processes. Abnormal Cu2+ ions concentrations are associated with various diseases, hence, can be used as diagnostic target. Monitoring copper ion is currently performed by non-portable, expensive and complicated to use equipment. We present a label free and a highly sensitive electrochemical ion-detecting biosensor based on a Gly-Gly-His tripeptide layer that chelate with Cu2+ ions. The proposed sensing mechanism is that the chelation results in conformational changes in the peptide that forms a denser insulating layer that prevents RedOx species transfer to the surface. This chelation event was monitored using various electrochemical methods and surface chemistry analysis and supported by theoretical calculations. We propose a highly sensitive ion-detection biosensor that can detect Cu2+ ions in the pM range with high SNR parameter.
Zinc
and copper are essential metal ions for numerous biological
processes. Their levels are tightly maintained in all body organs.
Impairment of the Zn2+ to Cu2+ ratio in serum
was found to correlate with many disease states, including immunological
and inflammatory disorders. Oxytocin (OT) is a neuropeptide, and its
activity is modulated by zinc and copper ion binding. Harnessing the
intrinsic properties of OT is one of the attractive ways to develop
valuable metal ion sensors. Here, we report for the first time an
OT-based metal ion sensor prepared by immobilizing the neuropeptide
onto a glassy carbon electrode. The developed impedimetric biosensor
was ultrasensitive to Zn2+ and Cu2+ ions at
physiological pH and not to other biologically relevant ions. Interestingly,
the electrochemical impedance signal of two hemicircle systems was
recorded after the attachment of OT to the surface. These two semicircles
suggest two capacitive regions that result from two different domains
in the OT monolayer. Moreover, the change in the charge-transfer resistance
of either Zn2+ or Cu2+ was not similar in response
to binding. This suggests that the metal-dependent conformational
changes of OT can be translated to distinct impedimetric data. Selective
masking of Zn2+ and Cu2+ was used to allow for
the simultaneous determination of zinc to copper ions ratio by the
OT sensor. The OT sensor was able to distinguish between healthy control
and multiple sclerosis patients diluted sera samples by determining
the Zn/Cu ratio similar to the state-of-the-art techniques. The OT
sensor presented herein is likely to have numerous applications in
biomedical research and pave the way to other types of neuropeptide-derived
sensors.
Sulfated saccharides are an essentialp art of extracellularm atrices, and they are involvedi nalarge number of interactions. Sulfated saccharide matricesi no rganismsa ccumulate heavy metal ions in addition to othere ssentialm etal ions. Accumulation of heavy metal ions alters the function of the organisms and cells, resulting in severea nd irreversible damage. The effect of the sulfation pattern of saccharides on heavym etal binding preferences is enigmatic because the accessibility to structurally definedsulfated sac-charides is limited and because standard analytical techniquescannot be used to quantify these interactions.Wedeveloped an ew strategy that combines enzymatic and chemicals ynthesis with surfacec hemistry and label-free electrochemical sensing to study the interactions between well-defined sulfated saccharides and heavy metal ions. By using these tools we showedt hat the sulfation pattern of hyaluronic acid governs their heavy metal ions binding preferences.
The brittle nature of the polymer beads used in SPPS dictates mild mixing techniques with low mass transfer. We demonstrate that vigorous overhead mechanical stirring with superior mass transfer properties kept the beads intact and significantly accelerates reaction kinetics and efficiency.
The presence of heavy metal ions such as copper in the human body at certain concentrations and specific conditions can lead to the development of different diseases. The currently available analytical detection methods remain expensive, time-consuming, and often require sample pre-treatment. The development of specific and quantitative, easy-in-operation, and cost-effective devices, capable of monitoring the level of Cu2+ ions in environmental and physiological media, is necessary. We use silicon nanoribbon (SiNR) ion-sensitive field effect transistor (ISFET) devices modified with a Gly–Gly–His peptide for the detection of copper ions in a large concentration range. The specific binding of copper ions causes a conformational change of the ligand, and a deprotonation of secondary amine groups. By performing differential measurements, we gain a deeper insight into the details of the ion–ligand interaction. We highlight in particular the importance of considering non-specific interactions to explain the sensors’ response.
Accelerating solid-phase synthesis
is crucial for accessing a large
number of peptides in a short time. Since standard peptide synthesis
is usually done under poor diffusion conditions with slow or no mixing
of the solid support, acceleration of the process is achieved by applying
a large excess of reagents. In this work, overhead stirring and heating
were combined to provide accelerated solid-phase peptide synthesis
without using an excess of reagent. A new setup that allows both heating
and fast stirring was designed specifically for research laboratory-scale
peptide synthesis. By increasing the diffusion of both reagents and
beads in a narrow dimension reactor, solid-phase reactions were done
in seconds and medium-size peptides were synthesized in minutes.
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