Sensors for Biomolecules

Since benzenethiols and aliphatic thiols endow similar chemical properties, it is still a challenge to construct probes to discriminate between them. To date, utilization of the thiolysis of dinitrobenzene sulfonylamides, 

The aforementioned probe show fluorescent turn-on signals upon interaction with benzenethiols. Moreover, probes 28 and 29 bear sulfoxide function at 3-position of BODIPY core. They are ratiometric probes for benzenethiols based on thiol-sulfoxide transduction. The two probes feature a distinct absorption and emission redshift upon reduction with benzenethiols to give 

ROS fail to induce significant emission enhancement, indieative of excellent selectivity to HNO over other biologieally relevant RNS. 

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Jacobs, C.B., Peairs, M.J., Venton, B.J. Carbon nanotube based electrochemical sensors for biomolecules. Anal. Chim. Acta 662, 105-127 (2010)... 

Several papers described the use of porphyrin-graphene hybrids as sensors for biomolecules. Thus, the electrochanical interactions between hemoglobin andH2TPPmadethehydroxypropyl-p-cyclodextrin/RGO/tetraphenylporphyrin composite a material with high biorecognition capability [127]. 

Jacobs CB, Peairs MJ, Venton BJ. Review carbon nanotube based electrochemical sensors for biomolecules. Analytica Chimica Acta 2010 662 105-27. http //dx.doi.0rg/lO.lOl6/j.aca.2OlO.Ol.OO9. 

Shiddiky MJA, Rahman MA, Cheol CS, Shim YB (2008) Fabrication of disposable sensors for biomolecule detection using hydrazine electrocatalyst. Anal Biochem 379(2) 170-175... 

We showed that these mesoporous silica materials, with variable pore sizes and susceptible surface areas for functionalization, can be utilized as good separation devices and immobilization for biomolecules, where the ones are sequestered and released depending on their size and charge, within the channels. Mesoporous silica with large-pore-size stmctures, are best suited for this purpose, since more molecules can be immobilized and the large porosity of the materials provide better access for the substrates to the immobilized molecules. The mechanism of bimolecular adsorption in the mesopore channels was suggested to be ionic interaction. On the first stage on the way of creation of chemical sensors on the basis of functionalized mesoporous silica materials for selective determination of herbicide in an environment was conducted research of sorption activity number of such materials in relation to 2,4-D. 

The intent of this chapter is not to provide an exhaustive review of chemical- and biosensors and probes, but rather to offer a brief overview of existing optical techniques and an indepth analysis of near-infrared (NIR) fluorogenic probes and sensors for the detection of metal ions, solution pH, and biomolecules and to present some of the latest results. 

Fig. 9.18 Evanescent sensor for (a) gases and (b) biomolecules (adapted from Lechuga etal.,2004)...

The fundamental fluorescence turn-on sensor described above for biomolecule detection can be used in many different formats for homogeneous assays. For example, one attractive formulation is a reverse assay (Fig. 2) wherein a molecule similar in structure and function to the ligand is sensed by having the fluorescent polymer and the QTL bioagent complex together. In this case,... 

This review is a survey of the research on the direct electron transfer (DET) between biomolecules and electrodes for the development of reagentless biosensors. Both the catalytic reaction of a protein or an enzyme and the coupling with further reaction have been used analytically. For better understanding and a better overview, this chapter begins with a description of electron transfer processes of redox proteins at electrodes. Then the behaviour of the relevant proteins and enzymes at electrodes is briefly characterized and the respective biosensors are described. In the last section sensors for superoxide, nitric oxide and peroxide are presented. These have been developed with several proteins and enzymes. The review is far from complete, for example, the large class of iron-sulfur proteins has hardly been touched. Here the interested reader may consult recent reviews and work cited therein [1,19]. 

A vast amount of literature exists on enzyme-modified metal nanopartides. Crumbliss and co-workers pioneered the use of metal nanopartides for enzymatic sensors for various analytes such as H2O2, glucose, xanthine and hypoxanthine [156-158]. GCE or Pt electrodes are modified with enzyme-capped Au colloids, either by simple evaporation or electrodeposition. The nanopartides act as mediators, transferring electrons between the redox-active site on the immobilized biomolecule and the electrode and thus eliminating the need for external mediators. These sensors are classified as third generation biosensors . 

As mentioned in the previous section, the response, the stability and the enzyme activity found greatly enhanced at the MWCNT platform. Other than CNTs, AuNPs also possess some unique properties and recent years it has been widely employed in the biosensors to immobilize biomolecules. Thus in this section we discuss about the application of AuNP matrix for the immobilization of AChE for pesticide sensor development. With the use of AuNPs, the efficiency and the stability of the pesticide sensor gets greatly amplified. Moreover, the nanoparticles matrix offers much friendly environment for the immobilized enzyme and thus the catalytic activity of the enzyme got greatly amplified. Interestingly, Shulga et al. applied AChE immobilized colloidal AuNPs sensor for the nM determination of carbofuran, a CA pesticide [16], The enzyme-modified electrode sensor was also utilized for the sensitive electrochemical detection of thiocholine from the enzyme catalyzed hydrolysis of acetylthiocholine chloride (ATCl). The fabrication and the enzyme catalyzed reaction at the AuNPs coated electrode surface is shown in Fig. 6. 

Napier, M.E., Loomis, C.R., Sistare. M.E., Kim, J., Eckhardt, A.E., and Thorp, H.H., 1997. Probing biomolecule recognition with electron transfer electrochemical sensors for DNA hybridization. Bioconjugate Chem., 8, pp. 906-913. 

Jensen JB, Pedersen LH, Hoiby PE, Nielsen LB, Eolkenberg JR, Riishede J, Noordegraaf D, Nielsen K, Carlsen A, Bjarklev A (2004) Photonic crystal fiber based evanescent-wave sensor for detection of biomolecules in aqueous solution. Opt Lett 29 1974-1976... 

Optical ring resonator sensors can be used to detect the R1 of the ring resonator surrounding medium or the presence of the bio/chemical molecules on the ring resonator surface. This section will focus on presenting examples of applications of optical ring resonator bio/chemical sensors for detection of chemical contaminants and a wide range of biomolecules. 

Hart, J.P. Wring, J.P. (1991). Carbon-based electrodes and their application as electrochemical sensors for selected biomolecules. Anal. Proc. 28, 4-7... 

Owing to their extremely hydrophobic character, diamond surfaces altogether hardly tend toward an unspecific adsorption of polar organic molecules. Therefore functionahzed diamond films suit very well to sensor applications, for example, for biomolecules. The specific adsorption then only takes place at the respective positions predetermined by the functionalization. 

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