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11.
《Arabian Journal of Chemistry》2022,15(3):103647
An optical biosensor for urea based on urease enzyme immobilised on functionalised calcium carbonate nanoparticles (CaCO3-NPs) was successfully developed in this study. CaCO3-NPs were synthesised from discarded cockle shells via a simple and eco-friendly approach, followed by surface functionalisation with succinimide ester groups. The fabricated biosensor is comprised of two layers. The first (bottom layer) contained functionalised NPs covalently immobilised to urease, and the second (uppermost layer) was alginate hydrogel physically immobilised to the pH indicator phenolphthalein. The biosensor provided a colorimetric indication of increasing urea concentrations by changing from colourless to pink. Quantitative urea analysis was performed by measuring the reflectance intensity of the colour change at a wavelength of 633.16 nm. The determination of urea concentration using this biosensor yielded a linear response range of 30–1000 mM (R2 = 0.9901) with a detection limit of 17.74 mM at pH 7.5. The relative standard deviation of reproducibility was 1.14%, with no signs of interference by major cations, such as K+, Na+, NH?+, and Mg2+. The fabricated biosensor showed no significant difference with the standard method for the determination of urea in urine samples. 相似文献
12.
A flow cell has been designed for use with an electrochemical enzyme biosensor, based on low-cost carbon-film electrodes. Three types of mediators were used: cobalt and copper hexacyanoferrates and poly(neutral red) (PNR), covered with glucose oxidase (GOx) immobilised by cross-linking with glutaraldehyde in the presence of bovine serum albumin or inside a oxysilane sol–gel network. Mixtures of sol–gel precursors were made from 3-aminopropyl-triethoxysilane (APTOS) together with methyltrimethoxysilane (MTMOS), methyltriethoxysilane (MTEOS), tetraethyloxysilane (TEOS) or 3-glycidoxypropyl-trimethoxysilane (GOPMOS), and the best chosen for encapsulation. Optimisation in batch mode, using amperometric detection at fixed potential, showed the PNR-GOx modified carbon-film electrodes to be best for flow analysis for both glutaraldehyde and sol–gel enzyme immobilisation. Both types of enzyme electrode were tested under flow conditions and the reproducibility and stability of the biosensors were evaluated. The biosensors were used for fermentation monitoring of glucose in grape must and interference studies were also performed. 相似文献
13.
Santanu Deb‐Choudhury Jeffrey E. Plowman Ancy Thomas Gail L. Krsinic Jolon M. Dyer Stefan Clerens 《Electrophoresis》2010,31(17):2894-2902
Identification of the intermediate filament proteins (IFPs) in the wool proteome has formerly been hampered by limited sequence information, the high degree of IFP homology and their close proximity on 2‐DE maps. This has been partially rectified by the recent acquisition of four new Type I and two Type II wool IFP sequences. Among closely migrating proteins, such as IFP clusters in a 2‐DE map, proteins with higher sequence coverage will be assigned higher scores, but the identification of unique peptides in such tight clusters may distinguish these closely migrating proteins. Two approaches were adopted for the study of wool IFPs. In the first, searches were conducted for peptides known to be unique to each member of the family in each spot. In the second, MALDI imaging was employed to examine peptides bound to a PVDF membrane from a poorly resolved part of the Type I IFP region of the 2‐DE map. As a result, a distinct picture has emerged of the distribution of the six Type I and four Type II IFPs across the 2‐DE wool protein map. 相似文献
14.
Comparative Study of Polymeric Supports as the Base of Immobilisation of Chemically Modified Enzymes
One of the difficulties in using optical biosensors based on enzymatic reactions is the immobilisation of the enzyme involved
in the determination. A detailed study has been carried out of the various polymeric supports which could provide a potential
alternative for the immobilisation of chemically modified enzymes. Before immobilisation, the enzyme is attached by means
of a covalent bond to a fluorescent probe, which is optically active in the visible region. The main advantage of this covalent
bond is that it is possible to follow the enzymatic reaction by fluorescence without the need for immobilising any further
reagent (reagentless biosensors). The results indicate that the most stable and reproducible polymeric supports are derived
from polyacrylamide obtained by UV photopolymerisation. The experiments have been carried out using chemically modified glucose
oxidase as the model enzyme. The films thus obtained have a lifetime of at least two months, an RSD of 9.2%, and a linear
range of 300 to 2000 mg L−1 of glucose. They are completely reversible by regeneration in an appropriate buffer solution. 相似文献
15.
Vasiliki Stavyiannoudaki Vicky Vamvakaki Nikos Chaniotakis 《Analytical and bioanalytical chemistry》2009,395(2):429-435
The properties of native and oxidised graphene layered carbon nanofibres are compared, and their utilisation in enzyme biosensor
systems using different immobilisation methods are evaluated. The efficient oxidation of carbon nanofibres with concentrated
H2SO4/HNO3 is confirmed by Raman spectroscopy while the introduction of carboxylic acid groups on the surface of the fibres by titration
studies. The oxidised fibres show enhanced oxidation efficiency to hydrogen peroxide, while at the same time they exhibit
a more efficient and selective interaction with enzymes. The analytical characteristics of biosensor systems based on the
adsorption or covalent immobilisation of the enzyme glucose oxidase on carbon nanofibres are compared. The study reveals that
carbon nanofibres are excellent substrates for enzyme immobilisation allowing the development of highly stable biosensor systems.
Figure Immobilization of proteins on carbon nanofibres 相似文献
16.
Tebogo R. Tsekeli Luthando Tshwenya Tsholofelo I. Sebokolodi Thabile Ndlovu Omotayo A. Arotiba 《Electroanalysis》2021,33(9):2053-2061
A nanocomposite platform of silver nanoparticles and carbon nanofibres (AgCNFs) was used to immobilise a bisphenol A specific 63-mer ssDNA aptamer to form a biosensor. The fabrication process of the biosensor was studied with electrochemical impedance spectroscopy and cyclic voltammetry in the presence of [Fe(CN)6]3−/4− as redox probe. The biosensor detected bisphenol A in a linear range of 0.1–10 nM, with a limit of detection of 0.39 nM using square wave voltammetry (SWV). The biosensor exhibited good selectivity in the presence of interfering species at 100-fold concentrations and was used to detect BPA in real water sample. 相似文献
17.
Elias Bou Maroun Agnès Hagège Christian Basset Eric Quéméneur Claude Vidaud 《Supramolecular chemistry》2013,25(7):585-590
With the aim of developing supports for uranyl cations immobilisation, new 1,3-alternate calix[4]arenes bearing both phosphonic acid functions as chelating sites and N-succinimide-4-oxabutyrate as the anchoring arm were synthesised in good yields. The coupling of such calixarenes to a gel was performed and a successful immobilisation of uranyl cations was obtained. 相似文献
18.
Alessandra BassoLuigi De Martin Cynthia EbertLucia Gardossi Paolo LindaFabrizio Sibilla 《Tetrahedron letters》2003,44(31):5889-5891
A novel application of organically modified silicates for covalent immobilisation of penicillin G acylase is reported. The immobilisation is efficient and the enzymatic preparation shows high specific activity and thermal stability. The technique opens new perspectives for the preparation of innovative tailor-made supports matching specific requirements of enzymatic processes. 相似文献
19.
20.
Robert Surma Danuta Wojcieszyska Jagna Karcz Urszula Guzik 《Molecules (Basel, Switzerland)》2021,26(4)
Pseudomonas moorei KB4 is capable of degrading paracetamol, but high concentrations of this drug may cause an accumulation of toxic metabolites. It is known that immobilisation can have a protective effect on bacterial cells; therefore, the toxicity and degradation rate of paracetamol by the immobilised strain KB4 were assessed. Strain KB4 was immobilised on a plant sponge. A toxicity assessment was performed by measuring the concentration of ATP using the colony-forming unit (CFU) method. The kinetic parameters of paracetamol degradation were estimated using the Hill equation. Toxicity analysis showed a protective effect of the carrier at low concentrations of paracetamol. Moreover, a pronounced phenomenon of hormesis was observed in the immobilised systems. The obtained kinetic parameters and the course of the kinetic curves clearly indicate a decrease in the degradation activity of cells after their immobilisation. There was a delay in degradation in the systems with free cells without glucose and immobilised cells with glucose. However, it was demonstrated that the immobilised systems can degrade at least ten succeeding cycles of 20 mg/L paracetamol degradation. The obtained results indicate that the immobilised strain may become a useful tool in the process of paracetamol degradation. 相似文献