The results obtained by this method suggest that a slight increase of carbon content was observed upon anodic activation of graphene SPE i

The results obtained by this method suggest that a slight increase of carbon content was observed upon anodic activation of graphene SPE i.e., from a value of (88.1 2.3)% to a value of Rabbit Polyclonal to PLD2 (92.8 1.7)%. electrodes, Tn antigen, glycan, biosensor, electrochemistry == 1. Introduction == The surface of every living cell is decorated with a compact layer of complex carbohydrates (glycans) adhered to a cell membrane. Thus, for an elementary understanding of biology it is important to get a detailed knowledge about the functions of glycans [1,2]. Over 50% of all proteins in organisms are modified by glycosylation and such a post-translational modification is crucial for regulation of many cellular processes. Glycans are built-up step-by-step using an enzymatic addition of carbohydrate building blocks to proteins/lipids [3]. Aberrant glycosylation is associated with many cellular properties involving cell proliferation, GW791343 HCl differentiation, transformation, migration, invasion, apoptosis, and immune responses. Cancer is one of the predominant diseases leading to mortality, with approximately 14.1 million new malignant cases with 8.2 million associated GW791343 HCl deaths every year [4]. Due to the progressive increase of the disease occurrence we can speak of a cancer epidemic [5]. Cancer cells undergo significant modifications in terms of glycan expression. Glycosylation patterns and level of glycans on the cell surfaces often give us information about the biological condition of the cells. Various GW791343 HCl tumor-associated carbohydrate antigens (TACAs) were identified to mediate key steps during cancer progression. For example TACAs such as the Thomsen-nouvelle (Tn; GalNAc-O-Ser/Thr), sTn (sialyl Tn; NeuAc2-6GalNAc-O-Ser/Thr), and Thomsen-Friedenreich (TF; Gall-3GalNAcl-O-Ser/Thr) [6,7] antigens can be used as diagnostic tumor markers and therapeutic targets [8]. The TF antigen is over-expressed in many carcinoma cells and it is biosynthesized from the Tn core. Correlation between levels of the TF and the Tn has never been observed [9]. However, the most common and very specific TACA is the Tn antigen discovered in 1957 [10]. The Tn antigen as a small glycan is expressed early in transformed cells and is the precursor for synthesis of other aberrantO-glycans [11]. Its presence was confirmed in 7090% of cancer types [11,12,13,14,15,16] and its expression corresponds with metastatic progression of the disease and a poor prognosis for cancer patients. On the other hand, good prognosis for cancer patients is associated with high levels of naturally generated anti-TACA antibodies (antibodies against aberrant glycans) [17]. Early cancer detection and personalized patient treatment are required in order to improve the survival rates of cancer patients [18]. Thus, cost-effective and simple tests and methods, which can detect cancer biomarkers in GW791343 HCl a mildly invasive or non-invasive way directly in serum/urine are required. Conventional instrumental-based methods have distinct drawbacks, when applied in glycomics and for diagnostic purposes [19], this is why affinity-based devices have a huge potential in cancer diagnostics [20]. Devices based on electrochemical methods offer ultrasensitive, rapid, simple, reliable, and economical assay protocols applicable also for biomarkers detection [21,22,23]. Nanotechnology is a driving force for advancements in many scientific disciplines including also cancer diagnostics, cancer therapy and glycomics [24,25]. Nanoparticles and nanomaterials with engineered surface characteristics can be effectively applied as scaffolds for displaying of glycans that allow precise surface positioning and higher density than using traditional approaches [22]. Furthermore, addition of nanomaterials such as NPs, carbon nanotubes (CNTs) or graphene may enhance sensitivity of biosensing [26,27]. The most prominent nanomaterial is graphene with unique physico-chemical characteristics. One-atom 2D thick layer ofsp2hybridized carbon atomsgraphene has fascinated the scientific community since the early description of its properties in 2004 [28,29]. Despite their short history, graphene-based materials are frequently used in (electro)biosensing thanks to their exceptional, unique and impressive electrical, thermal, optical and mechanical properties as a consequence of its configuration [30,31]. Moreover, depending on the purpose, graphene surface can be easily functionalized through GW791343 HCl non-covalent (- stacking, hydrophobic and electrostatic interactions) or covalent interaction (utilization of free oxygen groups in graphene oxide). Our recent study suggests [32] that unmodified graphene due to hydrophobic nature can effective denature proteins, that can result in development of interfacial layers exhibiting substantially compromised bioreceptive properties and/or being significantly prone to nonspecific protein binding, while working with complex samples like human serum. In our recent review paper we found out that several glycan biosensors developed on graphene modified interfaces offer quite high limits of detection (i.e., in the range of nMM) (see alsoTable 1in the current manuscript) [22]. In this manuscript.