This paper presents a novel ultrasensitive and rapid impedimetric biosensor with new immobilisation materials for parathyroid hormone (PTH) with the aim to determine the PTH level in serum for the diagnosis and monitoring of parathyroid diseases such as hyperparathyroidism, adenoma, and thyroid cancer. The interaction between PTH and the biosensor was investigated with an electrochemical method. The biosensor was based on the gold electrode modified by mercaptohexanol (6-MHL). Anti-parathyroid hormone (anti-PTH) was covalently immobilised onto a self-assembled monolayer (SAM) by using epiclorhidrina (EPI) with ethanolamine (EA). The EPI-EA interaction represents the first use of these for the construction of biosensors in published reports. The immobilisation of the anti-PTH was monitored by electrochemical impedance spectroscopy, cyclic voltammetry and scanning electron microscopy (SEM) techniques. After the optimisation studies of immobilisation materials such as 6-MHL, EPI, EA and glutaraldehyde, linearity, repeatability and sensitivity of biosensor were evaluated as the performance of biosensor. PTH was detected within a linear range of 0.1-0.6 pg/ml, and the detection limit was 0.1 fg/ml. The specificity of the biosensor was also investigated. Finally, the described biosensor was used to detect the PTH levels in artificial serum samples.
Calretinin (CAL) is calcium binding protein, and its levels in blood and cerebrospinal fluids are increased, since its expression is increased various cancer types. A novel biosensor system fabricated by immobilization of a specific antibody to CAL, anti‐Calretinin (anti‐CAL), onto a gold electrode surface via an effective covalent binding method using mercaptohexanol, epichlorohydrin, and ethanolamine was reported for the sensitive, selective, and accurate analysis of CAL. The proposed biosensor showed a linear calibration range between 1 ng/mL and 5 ng/mL. LOD and LOQ values were determined as 0.11 ng/mL and 0.38 ng/mL, respectively. The standard deviation related to the reproducibility of the new biosensor system was calculated as 3.95 %. Lastly, in order to state the applicability of the biosensor to early diagnosis of CAL in practice, artificial serum samples spiked with CAL have been analyzed by the proposed biosensor.
Thyroid-stimulating hormone (TSH) that regulates the synthesis of thyroid gland hormones controlling all metabolism is one of the pituitary hormones. Determination of TSH is crucial for monitoring thyroid gland-related disorders and some metabolic diseases.In this study, a non-labeled immunosensor based on covalent immobilization of anti-TSH antibody by using the formation of self-assembled monolayers (SAM) of 4mercaptophenylacetic acid (4-MPA) and functionalization of carboxyl ends with 1ethyl-3-(3-dimetilaminopropil) carbodiimide (EDC)/N-Hydroxysuccinimide (NHS) was fabricated for detection of TSH. Immobilization steps including the concentration of 4-2 MPA, the concentration of anti-TSH antibody and duration of anti-TSH antibody incubation were optimized by utilizing electrochemical impedance spectroscopy. Under optimal conditions, a sensitive, rapid and accurate determination of TSH at a concentration range between 0.7 -3.5 mIU/L was accomplished with a notable linearity and LOD value as 0.034 mIU/L as well as reproducibility and repeatability. Moreover, for comparison, linear range experiments were also carried out by using other electrochemical methods including Linear Sweep Voltammetry (LSV), Cyclic Voltammetry (CV) and capacitance spectroscopy (C). Finally, the constructed immunosensor was used for analyzing TSH levels spiked in the artificial serum samples.
ÖzLakkaz, moleküler oksijen kullanarak fenolik bileşikleri yükseltgeyen ve mantarlarda yaygınca bulunan bir enzimdir. Bu çalışmada, Stropharia aeruginosa, Trametes versicolor, Hypholoma fasciculare, Cantharellus cibarius, Clytocibe nebularis ve Amanita muscaria gibi mantar türlerinin lakkaz aktivitelerinin yanı sıra toplam protein miktarlarıının belirlenmesi ve kıyaslanması amaçlanmaktadır. Sonuçlar değerlendirildiğinde, en yüksek lakkaz aktivitesi değerinin Trametes versicolor türüne, en düşük aktivite değerinin de Amanita muscaria türüne ait olduğu gözlenmiştir. Ayrıca, Clytocibe nebularis ve Amanita muscaria türlerinin lakkaz aktivitesi ilk kez bu çalışmada rapor edilmiştir. Çalışmanın bir diğer hedefi de aktivitesi değeri görece yüksek olan ve daha önce biyosensör sistemlerinde kullanılmamış bir mantar türünün, doku homojenatı temelli bir biyosensör yapımında kullanılmasıdır. Bu bağlamda, Clytocibe nebularis dokusu kullanılarak geliştirilen biyosensör ile 100 -1000 µM aralığındaki artan katekol konsantrasyonları için doğrusal bir amperometrik yanıt elde edilmiştir.
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