5 Cyclic voltammograms of WSe2/rGO/GCE at different scan rates (A), linear dependence of peak current upon scan rates (B) Chronocoulometry test To demonstrate?the effect of WSe2 and rGO on improving the electrochemical active surface area and explore the effective specific surface area of the electrochemical immunosensor (WSe2/rGO/GCE), chronocoulometry?was performed in PBS (pH?=?7.0) containing 2.5?mM [Fe(CN)6]3?/4? and 0.1?M KCl. current response of the sensing interface. WSe2 was combined with rGO and the electrochemical active surface area (ECSA) of the sensing interface was enlarged to 2.1 occasions that of GCE. Finally, the combination of Velneperit flower-like WSe2 and rGO broadened the detection range and reduced the detection limit of the sensing platform. The immunosensor exhibited a high sensitivity with a wide linear range of 0.01C1000?ng/mL and low detection limit of 4.72?pg/mL. The real sample analysis of hIgG were conducted under optimal conditions, and the spiked recovery rates were between 95.5 and 104.1%. Moreover, satisfactory results were obtained by screening the stability, specificity and reproducibility of the immunosensor. Therefore, it can be concluded that the as-proposed immunosensor has the application potential of clinical analyze of hIgG in human serum. Graphical abstract Keywords: Label-free immunosensor, WSe2, Transition metal dichalcogenides, Human immunoglobulin G Introduction Human immunoglobulin G (hIgG) is usually one of 5 isotypes of immunoglobulin (IgM, IgG, IgE, IgA and IgD). It plays a vital role in immune response by activating complements [1] and neutralizing numerous toxins [2]. The hIgG is Velneperit usually?the main component of antibodies in human serum and represents about 75% of all immunoglobulins [3], which is widely distributed in serum and non-mucosal tissues [4]. The concentration range of it is 7C16?mg/mL in healthy adult serum [5]. Abnormal hIgG levels are often associated with a variety of diseases such as cancers [6], liver diseases [7], systemic lupus erythematosus [8] and inflammatory bowel diseases [9]. Thus, the level of hIgG has been used as an index for diagnosis and predicting the prognosis of diseases. For example, the COVID-19 disease has threatened global general public health in recent years. It was reported that high specific hIgG level was positively correlated with the severity of the disease at early stage [10]. Therefore, it is necessary for us to develop efficient methods to accurately measure the amount of hIgG in human body. Numerous methods have been developed for sensitively analyzing hIgG, including immunofluorescence assay [11], lateral circulation immunoassay (LFIA) [12], enzyme-linked immunosorbent assays?(ELISA) [13], and electrochemiluminescence (ECL) immunoassay [14]. Satisfactory results were obtained in the detection of hIgG using the above methods, there still exist some limits such as expensive devices, long assay time, and complicated operating?procedures. Among the numerous immunoassay methods, label-free electrochemical immunosensor is usually a promising method. It recognizes antigens by its corresponding antibodies that immobilized directly on the surface of sensing platform and monitors the concentration of the targets by measuring the electrochemical response. It has the superiorities of low cost, easy operation, quick response, high sensitivity, and miniaturized gear so that it has been widely applicated in the field of bioanalysis. Zhigang Yin et al. [15] developed a label-free electrochemical immunosensor based on PdPtCu@black phosphorus which required a short analysis time and achieved a low detection limit?of 23?pg/mL. In consider of its merits, label-free electrochemical immunosensor is an appropriate choice for clinical assay of hIgG. To enhance the sensitivity of the immunosensor, suitable materials should be exploited to raise the amounts of active sites around the sensing interface. Owing to the relatively high intrinsic hole mobility [16], sharp band edges [17] and strong light-matter interactions [18], two-dimensional transition metal dichalcogenides (TMDCs) have been a hot research topic in recent years. TMDCs have been extensively used in photocatalysis [19], field effect transistors [20], dye-sensitized solar Velneperit cells [21], etc. There are numerous users of TMDCs, such as MoS2, WS2, MoSe2 and WSe2 as well. Benefit from its unique properties, Tungsten Diselenide (WSe2) has become a hot issue in sensing technique?fields. WSe2 was used to construct field-effect transistor (FET) immunosensors and exhibited a moderate bandgap shows a high carrier mobilities [22]. Besides, profit from the high refractive index, WSe2 was applied to increase the refractive index of plasma resonance biosensors [23]. What has activated our interest is usually that the surface activity and surface defects? of WSe2 could bind small molecules effectively on its surface, thus WSe2 can be functionalized to weight biological molecules. Hae Won Lee et al. [24] have reported that after O2 plasma treatment, new binding sites of WSe2 appeared, so that WSe2 can combine more bioreceptors. In addition, in view of the Rabbit Polyclonal to ADCK2 large specific surface area, WSe2 has been used to design the sensing interface to.
