Procedia Technology最新文献

An electrochemical immunosensor for the simultaneous determination of ghrelin (GHRL) and peptide YY (PYY) using dual screen-printed carbon electrodes modified with reduced graphene oxide (rGO) is presented. Diazonium salt of 4-aminobenzoic acid (4-ABA) was electrochemically grafted on the modified electrodes allowing covalent immobilization of antibodies. After competitive immunoassays using alkaline phosphatase labelled antigens, the affinity reactions were monitored by DPV upon addition of 1-naphthyl phosphate. Calibration plots showed linear current vs. log [hormone] ranges from 10^-3 to 100 ng/mL GHRL, and 10^-4 to10 ng/mL PYY. The usefulness of dual immunosensor was demonstrated by analysis of spiked human serum and saliva.

Stilbenes have not been widely regarded as fluorophore labels due to their difficulty in conjugation. Quenched fluorescence of maleimide functionalized stilbene is found to be restored after thiol binding, enabling separation-free fluorophore labelling.

Herein, we report a scalable synthesis of multifunctional conducting polyacrylic acid (PAA) hydrogel (MFH) integrated with reduced grapheme oxide (rGO), vinyl substituted polyaniline (VS-PANI) and lutetium phthalocyanine (LuPc₂) as three dimensional robust matrix for glucose oxidase (GOx) immobilization (PAA-rGO/VS-PANI/LuPc₂/GOx-MFH). We have integrated the multicomponents such as PAA with rGO, VS-PANI through free radical polymerization using methylene bis-acrylamide, ammonium persulphate as the cross linker and initiator. The LuPc₂ was then doped to form multifunctional hydrogel (PAA-rGO/VS-PANI/LuPc₂-MFH). Finally, biosensor was fabricated by immobilizing GOx into PAA-rGO/VS-PANI/LuPc₂-MFH and subsequently used for electrochemical detection of glucose.

A hybrid graphene-polypyrrole (PPy) composite-based platform was elaborated by using nanosphere lithography structuration. This platform was further used for the antibody anti-acetaminophen immobilization in order to obtain an immunosensor for selective detection of paracetamol (acetaminophen) by using electrochemical methods. After patterning of the composite layer, the five-fold improvement of electrochemical signal was observed, suggesting that a higher amount of antibody was immobilized. This strategy permitted the ease and controlled immobilization of bioreceptors on the composite graphene-PPy platform and enhanced the sensitivity for paracetamol detection.

In this work, we have investigated the modeling, design and fabrication of bio-inspired artificial muscle unit capable of contracting according to the directives sent in form of chemical messengers. This new technology has the potential to revolutionize current robotics, because it could permit a paradigm shift in robots: from electro-mechanical devices to electro-chemical devices. The bio-inspired artificial muscle will be based on basic contractile units coupled to electrochemical sensors, with the purpose of allowing adaptive and flexible control similar to that in animal locomotion. An artificial nerve termination, able to modify the chemical characteristics of the inner environment, will generate directives in form of chemical messengers. Electro-chemical sensors have been used in order to detect the presence of the chemical messengers and transform them into electronic signals to be used in conventional control electronics. This study has been focused on the development and optimization of sensing materials for inorganic ions such as hydrogen ions. Among various conducting polymers studied, polyaniline (PANI) has attracted much attention due to its unique and controllable chemical and electrical properties. PANI layer has been electrochemically deposited on the gold arrays surface by cyclic voltammetry. Preliminary experiments on PANI-modified sensors in order to obtain the better sensitivity as chemical sensing used in artificial muscle unit have been carried out. To allow diffusion of chemical messages, the system has been immersed in wet environment. Using this approach, we study the effective possibility to control, assessing the performance in terms of accuracy of the control of the contraction, the impact of the delay due to the transmission time of the chemicals, precision and stability of control.

A study of B-type natriuretic peptide (BNP) antigen as a good prognostic marker for patients with heart failure antigen detection employing an electrochemical immunosensor is described here. Monoclonal anti-BNP capture antibody was immobilized on streptavidin-modified SPCEs to increase the sensitivity of the assay. An anti-BNP detection antibody conjugated with horseradish peroxidase enzyme (HRP) and 3,3,5,5’-tetramethybezidine dihydrochloride (TMB) was used as a substrate, in connection with voltammetric technique was achieve by measuring the peak current. Incorporation of a streptavidin/biotin system resulted in a well-oriented antibody immobilization of the capture antibody and consequently enhanced the sensitivity of the assay. Several optimizations were performed to reduce background signals; the optimal concentration of anti-BNP detection antibody needed, the time of SPCEs were first blocked with glycine, incubated with various concentrations of BNP and HRP-conjugated anti-BNP detection antibody (0 to 100.0 ng/mL), followed by electrochemical measurement were investigated,. In conclusion, this immunosensor greatly shortened and convenient for detection of heart failure diagnosis in real serum samples.

Two different graphene/β-cyclodextrin (CD)-based biosensors were elaborated for dopamine (DA) determination starting from glassy carbon electrode (GCE). First one was obtained by modifying GCE with reduced graphene oxide (RGO), CD and tyrosinase (Tyr) immobilized with a polyethylenimine film. The second biosensor was obtained after the incorporation of RGO functionalized with a new synthesized pyrrole-β-CD derivative and Tyr in an electropolimerized poly-amphiphilic pyrrole film. These two new approaches have resulted in selective and sensitive determination of DA in pharmaceuticals and real human samples.